CN116742697A - Large-scale photovoltaic power station upward compatible voltage coordination control method and system - Google Patents

Abstract

The invention discloses a voltage coordination control method and a system for upward compatibility of a large photovoltaic power station, wherein the method comprises the following steps: acquiring real-time values, upper limit values and lower limit values of grid-connected point voltages of the photovoltaic power station, real-time values, adjustable upper limit values and adjustable lower limit values of reactive powers of the photovoltaic inverter and the SVG, and calculating total reactive power shortage of the photovoltaic power station and the sum of reactive power increase and decrease margin of the photovoltaic power station and the SVG according to the acquired data; executing a reactive coordination control strategy based on a calculation result, and adjusting the voltage of the grid-connected point of the photovoltaic power station to a preset normal range; when the reactive coordination control strategy is executed, the time sequence of the cluster in the SVG and the photovoltaic power station participating in reactive coordination control is determined based on the capacity, the time interval of participating in regulation and fault information; and according to the voltage level of the grid-connected point of the current photovoltaic power station, carrying out voltage optimization and time sequence progressive control by taking the median value of the upper and lower limits of the voltage as a target. And the upward compatible voltage coordination control of the large photovoltaic power station can be realized.

Description

Large-scale photovoltaic power station upward compatible voltage coordination control method and system

Technical Field

The invention belongs to the field of reactive voltage optimization control of new energy stations of a power grid, and relates to an upward compatible voltage coordination control method and system of a large-scale photovoltaic power station.

Background

Under the background of a novel power system, more and more new energy sources participate in the voltage regulation process of the power grid. The daily voltage support of a large-scale photovoltaic power station is almost normal, however, the control schemes of all new energy manufacturers at present have different characteristics and forms, and the control schemes are very different when dealing with various complex working conditions. The hidden danger of burying down the power grid can be caused by insufficient adjustment, insufficient depth, insufficient precision or poor strategy coordination. Literature analysis shows that when the permeability of the photovoltaic power generation is higher than 30%, the voltage regulating capacity of the photovoltaic power generation is greatly improved, the effect of a capacitor can be replaced, and the voltage regulating level of a large photovoltaic power station is increased by one grade; the voltage regulating capability of the power grid is not required to stay on the level meeting the self voltage level and response scheduling, and the power grid has self-adaptive regulating capability within a certain range, so that the power grid can be further improved on the aspect of safety of the power grid or the aspect of maintaining the node voltage level.

In order to solve the problems of grid connection of the photovoltaic and safe operation of the power system, frame type specifications and related standards are formed at present, expert students do a great deal of research on power control and reactive voltage regulation, and although certain effects are achieved, the rapid development of a network source is difficult to adapt to under the background of the doubling of power electronic equipment; the problem of voltage fluctuation and out-of-limit is more frequent, and the problems of long-term high voltage and daily amplitude increase are more common in a large-scale new energy scene; most research is focused on the reactive voltage regulation control within photovoltaic power plants, which is currently less common in the field of reactive voltage control that includes upward compatibility of photovoltaic power plants.

Disclosure of Invention

In order to solve the defects in the prior art, the invention provides an upward compatible voltage coordination control method and system for a large photovoltaic power station.

The invention adopts the following technical scheme.

An upward compatible voltage coordination control method for a large photovoltaic power station comprises the following steps:

step 1, acquiring real-time values, upper limit values and lower limit values of grid-connected point voltages of a photovoltaic power station, real-time values, adjustable upper limit values and adjustable lower limit values of reactive power of a photovoltaic inverter and SVG, and calculating total reactive power shortage of the photovoltaic power station and total reactive power increase and decrease margin sum of the photovoltaic power station and SVG according to acquired data;

step 2, executing a reactive coordination control strategy based on the total reactive power shortage of the photovoltaic power station and the sum of reactive power increase and decrease margin of the photovoltaic power station and SVG, and adjusting the voltage of the grid-connected point of the photovoltaic power station to a preset normal range;

when the reactive coordination control strategy is executed, the time sequence of the cluster in the SVG and the photovoltaic power station participating in reactive coordination control is determined based on the capacity, the time interval of participating in regulation and fault information;

and 3, after the voltage is regulated to a preset normal range, carrying out voltage optimization and time sequence progressive control by taking the median of the upper and lower limits of the voltage as a target according to the voltage level of the grid-connected point of the current photovoltaic power station.

Preferably, in step 1, the total reactive power deficiency calculation formula of the photovoltaic power station is:

in the formula, deltaQ _up 、ΔQ _dn The total reactive power shortage when the reactive power of the photovoltaic power station is increased and reduced respectively;

U _r 、U _up and U _dn Real-time value and upper and lower limit values of PCC voltage of a public connection point of a photovoltaic power station access power grid are respectively obtained;

s is the sensitivity of the photovoltaic power plant, SVG and static var compensator to PCC voltage.

Preferably, in step 1, the calculation formula of the sum of the reactive power increase and decrease margins of the photovoltaic power station and the SVG is:

in the method, in the process of the invention,the sum of the reactive increase margin and the reactive decrease margin respectively represents reactive output capacity;

Q _{Xi_r} 、Q _{Xi_max} 、Q _{Xi_min} the real-time value, the adjustable upper limit and the adjustable lower limit of the reactive power of the ith photovoltaic inverter or SVG are respectively;

n is the number of photovoltaic inverters or SVGs;

subscript X takes G or SVG, representing photovoltaic power plant or SVG, respectively.

Preferably, in step 2, the strategy of reactive coordination control is: based on the total reactive power shortage of the photovoltaic power station, the sum of reactive power increase and decrease margins of the photovoltaic power station and the SVG and a preset normal range threshold value, judging the following contents and determining the reactive power increase and decrease amount of the corresponding photovoltaic power station and SVG and the input capacity of the static reactive compensator so as to perform reactive coordination control: whether reactive power is increased or decreased, whether current output of SVG is non-negative/non-positive, whether a photovoltaic power station singly adjusts to meet voltage regulation requirement or not, whether the SVG and the photovoltaic power station can meet the voltage regulation requirement after being set to zero or not together with adjustment of the photovoltaic power station, whether the photovoltaic power station and the SVG keep maximum reactive power output to be adjusted together to meet the voltage regulation requirement or not, and whether a static reactive compensator meeting the voltage regulation condition can be found or not, wherein the time sequence of the SVG and the cluster in the photovoltaic power station participating in reactive power coordination control after the reactive power increase is determined based on capacity, time interval participating in adjustment and fault information.

Preferably, in step 2, the strategy of reactive coordination control is specifically:

a) Judging whether to increase or decrease reactive power: according to the current grid-connected point voltage level of the photovoltaic power station, if the current grid-connected point voltage of the photovoltaic power station is lower than the lower threshold value of the preset normal range, the reactive power needs to be increased, and the method is changed into b) to continue to execute; if the voltage of the grid-connected point of the current photovoltaic power station is higher than the upper threshold value of the preset normal range, converting reactive power reduction into c) to continue to execute;

b) Adding reactive power, judging whether the current output of SVG is not negative: judging whether the current SVG is in a reactive state or a reactive state absorption state according to the SVG output value so as to execute a corresponding strategy; if the SVG output is not negative, converting to d) and continuing to execute; if the SVG output is negative, converting to e) and continuing to execute;

c) Subtracting reactive power, and judging whether the current output of SVG is not positive: judging whether the current SVG is in a reactive state or a reactive state absorption state according to the SVG output value so as to execute a corresponding strategy; if the SVG output is not positive, converting to f) and continuing to execute; if the SVG output is positive, turning to g) to continue execution;

d) SVG output is nonnegative, and whether the photovoltaic power station can meet the requirement by singly adjusting: reactive output capability of photovoltaic power stationAnd total reactive power deficiency delta Q _up Comparing and judging; if- >The requirement can be met by independently adjusting the photovoltaic power station, and at the moment, the reactive power increment of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _up SVG reactive power output delta Q _SVG The current adjustment is finished and enters a round detection state; if->The photovoltaic power station and the SVG are all involved in regulation, and at the moment, the process goes to h) to continue to be executed;

e) SVG output is negative, and whether the reactive power deficiency photovoltaic power station can be supplemented after the SVG is increased to 0 is judged: absolute value of SVG current reactive value |Q _{SVG_r} Current reactive margin of photovoltaicAnd total reactive power deficiency delta Q _up Comparing and judging; if it isThen it may be satisfied that, at this time, the SVG reactive delta is: ΔQ _SVG ＝|Q _{SVG_r} The reactive increment of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _up -|Q _{SVG_r} The adjustment is finished, and a round detection state is entered; if it isFailing to meet, at this time, go to h) to continue execution;

f) If the SVG output is not positive, judging whether the independent regulation of the photovoltaic power station can meet the requirement: reactive output capability of photovoltaic power stationAnd reactive shortage delta Q _dn Comparing and judging; if->Then the photovoltaic power station can meet the requirement by being independently regulated, and at the moment, the reactive power reduction amount of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _dn SVG reactive power output delta Q _SVG The current adjustment is finished and enters a round detection state; if->The photovoltaic power station and the SVG are all involved in regulation, and at the moment, the process goes to i) to continue to be executed;

g) If the SVG output is positive, judging whether the reactive power deficiency photovoltaic power station can be supplemented after the SVG is reduced to 0: absolute value of current value of SVG |Q _{SVG_r} Current margin of i and photovoltaicSum and total reactive power deficiency Δq _dn Comparing and judging; if it isThen it may be satisfied that the SVG reactive power reduction is: ΔQ _SVG ＝|Q _{SVG_r} The reactive power reduction of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _dn -|Q _{SVG_r} The adjustment is finished, and a round detection state is entered; if it isFailing to meet, at this point, go to i) continue execution;

h) Judging whether the photovoltaic power station and the SVG can be regulated together with the maximum reactive power output to meet the voltage regulation requirement: reactive output margin of photovoltaic power stationSVG margin->Sum and reactive deficiency Δq _up Comparing and judging; if it isThen it can be satisfied that, at this point, the photovoltaic power plant reactive delta is: />SVG reactive power increment is:the adjustment is finished, and a round detection state is entered; if->Judging whether a static reactive compensator meeting the voltage regulation condition can be found, determining the input static reactive compensator, updating the total reactive deficiency according to the input static reactive compensator capacity, and returning to the a) until the voltage returns to the normal range;

i) Judging whether the photovoltaic power station and the SVG can be regulated together with the maximum reactive power output to meet the voltage regulation requirement: reactive output margin of photovoltaic power station SVG margin->Sum and reactive deficiency Δq _dn Comparing and judging; if it isThen it can be satisfied that, at this point, the photovoltaic power plant reactive delta is: />SVG reactive power increment is:the adjustment is finished, and a round detection state is entered; if->And judging whether the static var compensator meeting the voltage regulation condition can be found, determining the input static var compensator, updating the total reactive power deficiency according to the input static var compensator capacity, and returning to the step a) until the voltage returns to the normal range.

Preferably, in h), judging whether the static var compensator meeting the voltage regulation condition can be found, determining the input static var compensator, updating the total reactive power deficiency according to the input static var compensator capacity, returning to a), and the specific process until the voltage returns to the normal range is as follows:

firstly judging whether the reactor is not withdrawn, if not, turning to I) to continue; if yes, go to II) continue to carry out;

i) No reactor is not withdrawn, and whether the capacitor C meeting the following conditions can be searched or not is judged _k1 ：

If C is searched _k1 Then put into capacitor C _k1 The method comprises the steps of carrying out a first treatment on the surface of the The required total reactive compensation amount deltaq is then determined _up Reset to DeltaQ _up -Q _Ck1 Returning to the step a) for next round of judgment until the voltage returns to the normal range;

If C is not searched _k1 Then it is determined whether or not the capacitor C satisfying the following condition can be searched _k2 ：

Q in _lim1 Step size limitation for increasing the maximum dead weight for a single time;

if C is searched _k2 Then throw in C _k2 After the adjustment is finished, entering a round detection state;

if C is not searched _k2 Then modify the criteriaThen continuously judging whether the capacitor C meeting the criterion can be searched _k3 Wherein Q is _lim2 For the modified step size limitation of single increment of maximum dead weight, lambda epsilon (a, b) is an adjustment coefficient, a=0.5, b<1 if C is searched _k3 Then throw in the C _k3 After the adjustment is finished, entering a round detection state; if C is not searched _k3 The reactive power increment of the photovoltaic power station is: /> SVG reactive power increment is: />Reactive deficiency is added again>Feeding back, after the adjustment is finished, and entering a round detection state;

II) if the reactor is not withdrawn, judging whether the reactor L meeting the following conditions can be searched _k1 ：

If search for L _k1 Then withdraw from the reactor L _k1 The method comprises the steps of carrying out a first treatment on the surface of the The required total reactive compensation amount deltaq is then determined _up Reset to DeltaQ _up -Q _Lk1 Substituting the voltage into the a) to perform the next round of judgment until the voltage returns to the normal range;

if not find L _k1 Then, it is determined whether or not the reactor L satisfying the following conditions can be searched _k2 ：

If search for L _k2 Exit L _k2 After the adjustment is finished, entering a round detection state;

if not find L _k2 Then modify the criteriaThen continuously judging whether the reactor L meeting the following conditions can be searched _k3 Wherein λε (a, b) is the upper limit adjustment coefficient, a=0.5, b<1 if search for L _k3 Exit L _k3 After the adjustment is finished, entering a round detection state; if not, go to I) perform the adjustment.

Preferably, in step 2, the time sequence of the cluster participating in reactive coordination control in the photovoltaic power station is determined based on the capacity, the time interval of participating in regulation, and fault information, and specifically:

different collector wires and subordinate modules in the photovoltaic power station are regarded as different photovoltaic clusters, and the time sequences of the different clusters participating in reactive coordination control are as follows:

OP＝sort{PRI _i }

in the formula, OP is a time schedule of different clusters participating in reactive coordination control;

PRI _i for the priority of cluster i, the calculation is as follows:

in CS _i Is the capacity size factor of cluster i;

Q _i reactive margin for cluster i;

Δq is the total reactive power deficiency currently allocated to the photovoltaic power plant;

TI _i a time interval factor for cluster i;

T _0-i the time interval duration of the last participation adjustment of the cluster i is the distance;

T _max maximum time interval allowed for two adjacent participating adjustments of the cluster;

FF _i Is a fault factor;

N _i the number of times cluster i has failed;

N _sum the total times of faults of all clusters in the whole photovoltaic power station are counted;

OF _i is a shielding factor;

P _i the active power value of the current cluster i;

P _max the maximum value of active power in all current clusters is obtained;

PRI _i the larger the value is, the higher the priority is, the stronger the reliability of the appointed reactive power support is, and the reactive power distribution is participated preferentially.

Preferably, in step 2, if there are multiple SVGs, removing the blocking factor from the timing sequence determining mode of the cluster participating in the reactive coordination control in the photovoltaic power station, and mapping the meaning correspondence of other variables to the SVGs to obtain the timing sequence priority of the SVGs participating in the reactive coordination control.

Preferably, in step 3, the step (U) _up +U _dn ) And/2, searching whether a static reactive compensator meeting the following conditions exists or not for the optimization target:

if the voltage exists, the capacitor is put into or the reactor is withdrawn from by judging whether the DeltaQ sign is put into or withdrawn from the static var compensator, if DeltaQ is negative, the capacitor is put into or withdrawn from the reactor, and if DeltaQ is positive, the capacitor is withdrawn from or put into the reactor, so that the voltage is optimized;

Δq is the total reactive power deficiency currently allocated to the photovoltaic power plant;

the timing progression control is started when Δq satisfies the following condition:

when the time sequence is controlled in a progressive way, the reactive power progressive amount is as follows:

Wherein x.epsilon. < -5,5 >.

The obtained DeltaQ _i After the progressive amount, ΔQ is used _i To update deltaq for voltage optimization.

A large photovoltaic power plant up-compatible voltage coordination control system comprising:

the reactive power shortage and margin calculation module is used for acquiring real-time values, upper limit values and lower limit values of the voltage of the grid-connected point of the photovoltaic power station, real-time values, adjustable upper limit values and adjustable lower limit values of the reactive power of the photovoltaic inverter and the SVG, and calculating the total reactive power shortage of the photovoltaic power station and the sum of reactive power increase and decrease margins of the photovoltaic power station and the SVG according to the acquired data;

the reactive power coordination control module is used for executing a reactive power coordination control strategy based on the total reactive power shortage of the photovoltaic power station and the sum of reactive power increase and decrease margins of the photovoltaic power station and the SVG, and adjusting the voltage of the grid-connected point of the photovoltaic power station to a preset normal range;

when the reactive coordination control strategy is executed, the time sequence of the cluster in the SVG and the photovoltaic power station participating in reactive coordination control is determined based on the capacity, the time interval of participating in regulation and fault information;

and the voltage optimization and time sequence progressive control module is used for performing voltage optimization and time sequence progressive control by taking the upper and lower limit median values of the voltage as targets according to the voltage level of the grid-connected point of the current photovoltaic power station after the voltage is regulated to a preset normal range.

The invention has the beneficial effects that compared with the prior art:

according to the method, the voltage regulation characteristics of the photovoltaic inverter, the SVG and the static var compensator are integrated, and the total reactive power shortage of the photovoltaic power station and the reactive power margin of each reactive power source which can participate in regulation are calculated on the premise that the voltage self-adaptive regulation and control capability construction of the increasingly common large photovoltaic power station is researched; then, a reactive coordination control strategy is formulated, a regulation and control time schedule is generated and executed; and finally, voltage optimization is carried out, the voltage level is improved, and reactive voltage coordination control which is suitable for upward compatibility of a large-scale photovoltaic power station is realized. The invention utilizes the voltage regulation characteristics among reactive power sources to carry out coordination control and carry out voltage progressive optimization operation, reduces frequent control time and provides high-quality voltage level on the premise of guaranteeing basic voltage level, and can keep high-quality voltage level and maximum reactive margin for a long time. The method not only can meet short-time voltage support, but also can optimize and coordinate the coordination of reactive power sources to a certain extent, lighten the upper-level dispatching pressure, and can reduce the occurrence probability of voltage fluctuation and cascading failure when handling sudden failure; and the maximum reactive margin of the SVG is kept at all times, so that the maximum support of reactive power shortage in an emergency state is ensured.

The invention provides coordinated control of multiple reactive power sources and optimization operation of voltage levels, which are carried out by supporting through SVG and inverter with rapid reactive power supporting capability, voltage is regulated back to normal level, and optimization is carried out after the voltage returns to normal, so that voltage transient response in short time scale and high-quality voltage level in long time scale can be satisfied, and the method is specific:

in the aspect of calculation of reactive power deficiency and total reactive power increment, different from the deviation possibly brought by conventional theoretical calculation, the method fully utilizes the voltage sensitivity parameters of key nodes in the regional power grid platform, increases the coupling degree between different power grid systems and enhances the reliability;

in the aspect of reactive power coordination control strategies, considering that most of researches at present are focused on controlling an inverter in a station, and neglecting coordination control with other different reactive power sources, a few of the researches also consider control among different reactive power sources, but do not distinguish long and short time scales, so that the problem that the control effect is not ideal or the desired effect is not achieved is solved. The maximum reactive margin of the SVG is kept at all times, and the maximum support of reactive power shortage in an emergency state is ensured;

In the aspect of field-level voltage optimization and progressive control, aiming at most researches and not involving, few researches focus on multi-objective optimization algorithms, which are unnecessary for field-level voltage control and cause great resource waste, the application directly takes high-quality voltage level as a control target and adopts a progressive control method when necessary; the occurrence probability of voltage fluctuation and cascading failure can be reduced when the sudden failure is dealt with; the high-quality voltage level is ensured, the dispatching pressure of the upper-level voltage is reduced, and the upward compatible voltage regulating strategy is integrally realized.

Drawings

FIG. 1 is a flow chart of steps of a reactive voltage coordination control method for a large-scale photovoltaic power station;

FIG. 2 is a flowchart of a photovoltaic inverter and SVG reactive coordination control strategy;

fig. 3 is a flow chart of a coordinated control strategy of a static var compensator.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. The described embodiments of the application are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art without making any inventive effort, are within the scope of the present application.

As shown in fig. 1-3, embodiment 1 of the present invention provides a method for controlling voltage coordination of large photovoltaic power station with upward compatibility, in a preferred but non-limiting embodiment of the present invention, the method includes the following steps:

step 1, acquiring real-time values, upper limit values and lower limit values of grid-connected point voltages of a photovoltaic power station, real-time values, adjustable upper limit values and adjustable lower limit values of reactive power of a photovoltaic inverter and SVG, and calculating total reactive power shortage of the photovoltaic power station and total reactive power increase and decrease margin sum of the photovoltaic power station and SVG according to acquired data;

in specific implementation, current reactive capacity and threshold information of a photovoltaic power station, SVG (static var compensator) and a Static Var Compensator (SVC) are obtained, and according to reactive regulation characteristics of the photovoltaic inverter, the SVG and a capacitor bank, the total reactive power shortage of the photovoltaic power station and reactive power margin which can be regulated by each reactive power source are calculated, namely the reactive power increase and decrease margin and the required reactive power total amount of the photovoltaic power station and the SVG which are controlled;

further preferably, the sum of the respective reactive power increase and decrease margins participating in the control is calculated according to the obtained reactive power capacity and the current residual reactive power capacity information of the photovoltaic power station and the SVG, and then the increment of the photovoltaic power station and the SVG participating in the adjustment is determined according to the current reactive power shortage and the increase and decrease margins.

And (3) calculating the total reactive power shortage of the photovoltaic power station: calculating reactive power shortage of the current system, setting real-time value, upper and lower voltage of PCC (point of common connection) of a photovoltaic power station to an electric networkThe limit values are U respectively _r 、U _up And U _dn The following steps are:

wherein S is the sensitivity of the photovoltaic power station, SVG and static var compensator to PCC voltage.

And (3) calculating the sum of the reactive power increase and decrease margins of the photovoltaic power station and the SVG: calculating reactive margin sum of photovoltaic power station and SVG participating in controlSum of margin reduction>

Wherein X represents a photovoltaic power station or SVG, and X is E (G, SVG);

Q _{Xi_r} 、Q _{Xi_max} 、Q _{Xi_min} the real-time value, the adjustable upper limit and the adjustable lower limit of the reactive power of the ith photovoltaic inverter or SVG are respectively;

n is the number of photovoltaic inverters or SVGs.

Step 2, executing a reactive coordination control strategy based on the total reactive power shortage of the photovoltaic power station and the sum of reactive power increase and decrease margin of the photovoltaic power station and SVG, and adjusting the voltage of the grid-connected point of the photovoltaic power station to a preset normal range;

further preferably, the strategy of reactive coordination control is: based on the total reactive power shortage of the photovoltaic power station, the sum of reactive power increase and decrease margins of the photovoltaic power station and the SVG and a preset normal range threshold value, judging the following contents and determining the reactive power increase and decrease amount of the corresponding photovoltaic power station and SVG and the input capacity of the static reactive compensator so as to perform reactive coordination control: whether reactive power is increased or decreased, whether current output of SVG is non-negative/non-positive, whether a photovoltaic power station singly adjusts to meet voltage regulation requirements or not, whether the SVG and the photovoltaic power station can meet the voltage regulation requirements after being set to zero or not together with adjustment of the photovoltaic power station, whether the photovoltaic power station and the SVG keep maximum reactive power output to be adjusted together can meet the voltage regulation requirements or not, and whether a static reactive compensator meeting the voltage regulation conditions can be found or not, wherein the time sequence of the SVG after the reactive power increase is decreased and the cluster in the photovoltaic power station to participate in reactive power coordination control is determined based on capacity, time interval participating in adjustment and fault information;

As shown in fig. 2, the timing strategies for generating the photovoltaic inverter and the SVG to participate in voltage regulation are sequentially determined according to the following sequence: whether reactive power is added, whether current output of SVG is non-negative, whether the photovoltaic power station is independently regulated to meet the requirement, whether the photovoltaic power station can be supplemented to adjust the SVG output to the residual reactive power shortage after zero, whether a static reactive compensator meeting the condition can be found or not, specifically comprises the following steps:

a) Judging whether to increase or decrease reactive power: according to the current voltage level of the grid-connected point of the photovoltaic power station, if the current voltage is lower than a lower threshold value of a preset normal range, the reactive power needs to be increased, and the method is changed into b) to continue to be executed; if the current voltage is higher than the upper threshold value of the preset normal range, converting the reactive power reduction into c) to continue to be executed;

b) Adding reactive power, judging whether the current output of SVG is not negative: judging whether the current SVG is in a reactive state or a reactive state absorption state according to the SVG output value so as to execute a corresponding strategy; if the SVG output is not negative, converting to d) and continuing to execute; if the SVG output is negative, converting to e) and continuing to execute;

c) Subtracting reactive power, and judging whether the current output of SVG is not positive: judging whether the current SVG is in a reactive state or a reactive state absorption state according to the SVG output value so as to execute a corresponding strategy; if the SVG output is not positive, converting to f) and continuing to execute; if the SVG output is positive, turning to g) to continue execution;

d) SVG output is nonnegative, and whether the photovoltaic power station can meet the requirement by singly adjusting: reactive output capability of photovoltaic power stationAnd total reactive power deficiency delta Q _up Comparing and judging; if->The requirement can be met by independently adjusting the photovoltaic power station, and at the moment, the reactive power increment of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _up SVG reactive power output delta Q _SVG The adjustment is finished, and the state of round detection is entered (namely, the step 1 is returned to acquire data calculation again, and then series judgment is carried out); if it isThe photovoltaic power station and the SVG are all involved in regulation, and at the moment, the process goes to h) to continue to be executed;

it can be understood that, proceeding to the step of ending the current adjustment, the voltage has already returned to normal, then "entering the round detection" is to make the next judgment, if the voltage has not returned to normal, also make corresponding processing, then continue the round detection, enter the next detection, the whole flow is expressed by the following program:

main()

{.....

while circulation body

{...

Step 1;

while (voltage threshold crossing condition is satisfied) { step 2} "turn around monitoring" means that the cycle is skipped and the outer cycle is performed.

if () step 3; ...

}...

}

e) SVG output is negative, and whether the reactive power deficiency photovoltaic power station can be supplemented after the SVG is increased to 0 is judged: absolute value of SVG current reactive value |Q _{SVG_r} Current reactive margin of photovoltaicAnd total reactive power deficiency delta Q _up Comparing and judging; if it isThen it may be satisfied that, at this time, the SVG reactive delta is: ΔQ _SVG ＝|Q _{SVG_r} The reactive increment of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _up -|Q _{SVG_r} The adjustment is finished, and a round detection state is entered; if it isFailing to meet, at this time, go to h) to continue execution;

f) If the SVG output is not positive, judging whether the independent regulation of the photovoltaic power station can meet the requirement: reactive output capability of photovoltaic power stationAnd reactive shortage delta Q _dn Comparing and judging; if->Then the photovoltaic power station can meet the requirement by being independently regulated, and at the moment, the reactive power reduction amount of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _dn SVG reactive power output delta Q _SVG The current adjustment is finished and enters a round detection state; if->The photovoltaic power station and the SVG are all involved in regulation, and at the moment, the process goes to i) to continue to be executed;

g) If the SVG output is positive, judging whether the reactive power deficiency photovoltaic power station can be supplemented after the SVG is reduced to 0: absolute value of current value of SVG |Q _{SVG_r} Current margin of i and photovoltaicSum and total reactive power deficiency Δq _dn Comparing and judging; if it isThen it may be satisfied that the SVG reactive power reduction is: ΔQ _SVG ＝|Q _{SVG_r} The reactive power reduction of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _dn -|Q _{SVG_r} The adjustment is finished, and a round detection state is entered; if it is Failing to meet, at this point, go to i) continue execution;

h) Judging whether the photovoltaic power station and the SVG can be regulated together with the maximum reactive power output to meet the voltage regulation requirement: reactive output margin of photovoltaic power stationSVG margin->Sum and reactive deficiency Δq _up Comparing and judging; if it isThen it can be satisfied that, at this point, the photovoltaic power plant reactive delta is: />SVG reactive power increment is:the adjustment is finished, and a round detection state is entered; if->Judging whether the static var compensator meeting the voltage regulation condition can be found, determining the input static var compensator, updating the total reactive power deficiency according to the input static var compensator capacity, returning to the a), and calling the static var compensator C until the voltage returns to the normal range _k Takes part in regulation, residual reactive power deficiency delta Q _up -Q _Ck Supplemented by photovoltaic power plant and SVG, wherein Q _Ck Is a static reactive compensator C _k Specifically determining the capacity of C _k See first case below.

i) Judging whether the photovoltaic power station and the SVG can be regulated together with the maximum reactive power output to meet the voltage regulation requirement: reactive output margin of photovoltaic power stationSVG margin->Sum and reactive deficiency Δq _dn Comparing and judging; if it isThen it can be satisfied that, at this point, the photovoltaic power plant reactive delta is: / >SVG reactive power increment is:the adjustment is finished, and a round detection state is entered; if->Judging whether the static var compensator meeting the voltage regulation condition can be found, determining the input static var compensator, updating the total reactive power deficiency according to the input static var compensator capacity, returning to the a), and calling the static var compensator L until the voltage returns to the normal range _k Takes part in regulation, residual reactive power deficiency delta Q _dn -Q _Lk Supplemented by photovoltaic power plant and SVG, wherein Q _Lk Is a static var compensator L _k Specifically determining L _k See second case below.

The above-mentioned judgement can find the static var compensator that satisfies the voltage regulation condition and confirm the static var compensator that drops into, update the total reactive deficiency according to the static var compensator capacity that drops into, return a), until the mode that the voltage returns to the normal range is:

first, for the reactive power to be added: firstly judging whether the reactor is not withdrawn, if not, turning to I) to continue; if yes, go to II) continue to carry out; fig. 3 depicts this process.

I) No reactor is not withdrawn, and whether the capacitor C meeting the following conditions can be searched or not is judged _k1 ：

If C is searched _k1 Then put into capacitor C _k1 The method comprises the steps of carrying out a first treatment on the surface of the The required total reactive compensation amount deltaq is then determined _up Reset to DeltaQ _up -Q _Ck1 And substituting the voltage into the voltage in the a) to detect and judge the next round until the voltage returns to the normal range.

If C is not searched _k1 Then it is determined whether or not the capacitor C satisfying the following condition can be searched _k2 ：

Q in _lim1 A step size limit defined as a single increase in maximum dead volume;

if C is searched _k2 Then throw in C _k2 After the adjustment is finished, entering a round detection state;

if C is not searched _k2 Then modify the criteriaThen continuously judging whether the capacitor C meeting the criterion can be searched _k3 Wherein λε (a, b) is defined as the adjustment coefficient, the larger the value thereof, the closer the capacitor voltage is to the upper limit after being put into operation, wherein a=0.5, b<1, b can be specifically set in advance according to the capacity of the capacitor to be configured (default value is 0.9), if C is found _k3 Then throw in the C _k3 After the adjustment is finished, entering a round detection state; if C is not searched _k3 The reactive power increment of the photovoltaic power station is: />SVG reactive power increment is: />Reactive shortage is then carried outAnd feeding back, and entering a round detection state after the adjustment is finished.

II) if the reactor is not withdrawn, judging whether the reactor L meeting the following conditions can be searched _k1 ：

If search for L _k1 Then withdraw from the reactor L _k1 The method comprises the steps of carrying out a first treatment on the surface of the The required total reactive compensation amount deltaq is then determined _up Reset to DeltaQ _up -Q _Lk1 And substituting the voltage into the above a) to detect and carry out the next round of judgment until the voltage returns to the normal range.

If not find L _k1 Then, it is determined whether or not the reactor L satisfying the following conditions can be searched _k2 ：

If search for L _k2 Exit L _k2 After the adjustment is finished, entering a round detection state;

if not find L _k2 Then modify the criteriaThen continuously judging whether the reactor L meeting the following conditions can be searched _k3 Wherein λ∈ (a, b) is defined as the upper limit adjustment coefficient, the larger the value thereof, the closer the capacitor voltage after being put into operation is to the upper limit, wherein a=0.5, b<1, b can be specifically set in advance (default value is 0.9) according to the capacity of the capacitor to be configured, if L is found _k3 Exit L _k3 After the adjustment is finished, entering a round detection state; if not, go to I) perform the adjustment.

In the second case, for the reactive power to be subtracted: firstly judging whether a capacitor does not exit, if not, turning to III) to continue; if yes, go to IV) continue to carry out; fig. 3 depicts this process.

III) no capacitor is withdrawn, and whether the reactor L meeting the following conditions can be searched or not is judged _k1 ：

If search for L _k1 Then put into the capacitor L _k1 The method comprises the steps of carrying out a first treatment on the surface of the The required total reactive power reduction Δq is then determined _dn Reset to DeltaQ _dn -Q _Lk1 And substituting the voltage into the voltage in the above a) to detect and judge the next round until the voltage returns to the normal range.

If not find L _k1 Then, it is determined whether or not the reactor L satisfying the following conditions can be searched _k2 ：

Q in _l ^′ _im A step size limit defined as a single reduction of the maximum amount of work;

if search for L _k2 Then put into L _k2 After the adjustment is finished, entering a round detection state;

if not find L _k2 Then modify the criteriaContinuing the determination, wherein λε (a, b) is defined as the adjustment coefficient, the larger the value thereof, the closer the capacitor voltage is to the upper limit after being put into operation, wherein a=0.5, b<1, b can be specifically set in advance according to the capacity of the configured capacitor (default value is 0.9), lambda defaults to 0.6, if L is found _k3 Then throw in the L _k3 After the adjustment is finished, entering a round detection state; if not find L _k3 The reactive power reduction of the photovoltaic power station is:SVG reactive power reduction is: />And feeding back the reactive power shortage, and entering a recurrent detection state after the current regulation is finished.

IV) if there is no capacitor exit, judging whether the capacitor C meeting the following conditions can be searched _k1 ：

If C is searched _k1 Exit capacitor C _k1 The method comprises the steps of carrying out a first treatment on the surface of the The required total reactive compensation amount deltaq is then determined _dn Reset to DeltaQ _dn -Q _Ck1 And substituting the voltage into the voltage in the a) to detect and judge the next round until the voltage returns to the normal range.

If C is not searched _k1 Then it is determined whether or not the capacitor C satisfying the following condition can be searched _k2 ：

If C is searched _k2 Exit C _k2 After the adjustment is finished, entering a round detection state;

if C is not searched _k2 Then modify the criteriaThen, whether the capacitor C meeting the following conditions can be searched is continuously judged _k3 Wherein λε (a, b) is defined as the adjustment coefficient, the larger the value thereof, the closer the capacitor voltage is to the upper limit after being put into operation, wherein a=0.5, b<1, b can be specifically set in advance according to the capacity of the configured capacitor (default value is 0.9), and if the capacitor is searched, the capacitor is withdrawn from C _k3 After the adjustment is finished, entering a round detection state; if not, go to III) continue to perform the adjustment.

Further preferably, the timing schedule of the voltage support is determined by taking into account the comprehensive factors of different clusters of the photovoltaic power plant:

different collector wires and subordinate modules in the photovoltaic power station are regarded as different photovoltaic clusters, and the time sequences of the different clusters participating in reactive coordination control are as follows:

OP＝sort{PRI _i }

in the formula, OP is a time schedule of different clusters participating in reactive coordination control;

PRI _i For the priority of cluster i, the calculation is as follows:

in CS _i Taking the capacity size factor of the cluster i as the capacity size factor of the cluster;

Q _i reactive margin for cluster i;

Δq is the total reactive power deficiency currently allocated to the photovoltaic power plant, Δq is Δq _up Or DeltaQ _dn Delta Q is delta Q when the photovoltaic power station increases reactive power and decreases reactive power _up 、ΔQ _dn ；

TI _i Taking the time interval duration of the cluster from the last time of the adjustment into consideration as the time interval factor of the cluster i;

T _0-i the time interval duration of the last participation adjustment of the cluster i is the distance;

T _max maximum time interval allowed for two adjacent participating adjustments of the cluster;

FF _i as a fault factor, the size of the probability of the cluster to fail is considered;

N _i the number of times cluster i has failed;

N _sum the total times of faults of all clusters in the whole photovoltaic power station are counted;

OF _i taking the current blocked degree of the cluster into consideration as a blocking factor;

P _i the active power value of the current cluster i;

P _max is the maximum of the active power in all clusters currently.

PRI _i The larger the value is, the higher the priority is, the stronger the reliability of the appointed reactive power support is, and the reactive power distribution is participated preferentially.

If a plurality of SVGs exist, the priority determining method is the same as that above, the shielding factors are removed, and other variable meanings are mapped to the SVGs correspondingly.

From the above, the reactive coordination control strategy is formulated and the regulation and control time schedule considering the comprehensive factors is generated; judging whether the following conditions meet the requirements in sequence and executing corresponding strategies: whether reactive power is added, whether the current output of SVG is non-negative/positive, whether the requirement is met by independently adjusting a photovoltaic power station, whether the SVG can meet the requirement by adjusting the SVG and the photovoltaic power station together after zeroing, whether the requirement can be met by adjusting the photovoltaic power station and the SVG together with the maximum reactive power output, and whether the static reactive power compensator meeting the condition can be found to meet the voltage regulation. And executing the strategy according to a time schedule generated by taking the comprehensive factors into consideration until the current voltage regulation requirement is met.

And 3, after the voltage is regulated to a preset normal range, performing voltage optimization and time sequence progressive control by taking the upper and lower voltage limit median values as targets according to the voltage level of the grid-connected point of the current photovoltaic power station, namely performing time sequence progressive voltage optimization operation by taking the upper and lower voltage limit median values as targets according to the current voltage level, and optimizing the voltage level.

Further preferably, after the voltage regulation in the normal range, the voltage falls within the normal range, and the voltage optimizing operation is performed at this time to (U) _up +U _dn ) And/2, searching whether a static reactive compensator meeting the following conditions exists or not for the optimization target:

If the voltage exists, the capacitor is put into or the reactor is withdrawn from by judging whether the DeltaQ sign is put into or withdrawn from the static var compensator, if DeltaQ is negative, the capacitor is put into or withdrawn from the reactor, and if DeltaQ is positive, the capacitor is withdrawn from or put into the reactor, so that the voltage is optimized;

it will be appreciated that the actual voltage must be presentIn error (U) _up +U _dn ) 2 is only one target, which may never be reached but only accessible; and may not find such capacitive reactance to be inactive; because of the constraints, it is sufficient to make a decision here each time, there is no repeated search, either if appropriate to go on and off, or if no action is found.

When the Δq satisfies the following condition in coping with the large-capacity reactive power replacement, the timing progressive control is started:

when the time sequence is controlled in a progressive way, the reactive power progressive amount is as follows:

in the formula, deltaQ _i For each reactive progressive amount, x E [ -5,5]The value of x is the progressive times N, the manual change can be realized, the larger the default value is 5,N, the smoother the regulating curve, and the better the control effect on the short-time voltage abrupt change working condition is.

The obtained DeltaQ _i After the progressive amount, ΔQ is used _i And updating delta Q of the three formulas to perform optimization control, so as to finish voltage optimization.

The time sequence progression of the invention means when the target control amount exceeds A control method started at the time avoids the situation that the voltage fluctuation is increased due to the fact that the control step length is too large.

The embodiment 2 of the invention provides an upward compatible voltage coordination control system of a large photovoltaic power station, which comprises the following components:

the reactive power shortage and margin calculation module is used for acquiring real-time values, upper limit values and lower limit values of the voltage of the grid-connected point of the photovoltaic power station, real-time values, adjustable upper limit values and adjustable lower limit values of the reactive power of the photovoltaic inverter and the SVG, and calculating the total reactive power shortage of the photovoltaic power station and the sum of reactive power increase and decrease margins of the photovoltaic power station and the SVG according to the acquired data;

the reactive power coordination control module is used for executing a reactive power coordination control strategy based on the total reactive power shortage of the photovoltaic power station and the sum of reactive power increase and decrease margins of the photovoltaic power station and the SVG, and adjusting the voltage of the grid-connected point of the photovoltaic power station to a preset normal range;

when the reactive coordination control strategy is executed, the time sequence of the cluster in the SVG and the photovoltaic power station participating in reactive coordination control is determined based on the capacity, the time interval of participating in regulation and fault information;

and the voltage optimization and time sequence progressive control module is used for performing voltage optimization and time sequence progressive control by taking the upper and lower limit median values of the voltage as targets according to the voltage level of the grid-connected point of the current photovoltaic power station after the voltage is regulated to a preset normal range.

A terminal comprising a processor and a storage medium; the storage medium is used for storing instructions;

the processor is configured to operate in accordance with the instructions to perform the steps of the method.

A computer readable storage medium having stored thereon a computer program which when executed by a processor realizes the steps of the method.

The invention has the beneficial effects that compared with the prior art:

according to the method, the voltage regulation characteristics of the photovoltaic inverter, the SVG and the static var compensator are integrated, and the total reactive power shortage of the photovoltaic power station and the reactive power margin of each reactive power source which can participate in regulation are calculated on the premise that the voltage self-adaptive regulation and control capability construction of the increasingly common large photovoltaic power station is researched; then, a reactive coordination control strategy is formulated, a regulation and control time schedule is generated and executed; finally, voltage optimization is carried out, the voltage level is improved, the upward compatible voltage coordination control of the large photovoltaic power station is realized, short-time voltage support can be met, the coordination of reactive power sources can be optimized and coordinated to a certain extent, the upper-level dispatching pressure is reduced, and the occurrence probability of voltage fluctuation and cascading failure can be reduced when sudden failure is handled; and the maximum reactive margin of the SVG is kept at all times, so that the maximum support of reactive power shortage in an emergency state is ensured.

The present disclosure may be a system, method, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for causing a processor to implement aspects of the present disclosure.

The computer readable storage medium may be a tangible device that can hold and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: portable computer disks, hard disks, random Access Memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static Random Access Memory (SRAM), portable compact disk read-only memory (CD-ROM), digital Versatile Disks (DVD), memory sticks, floppy disks, mechanical coding devices, punch cards or in-groove structures such as punch cards or grooves having instructions stored thereon, and any suitable combination of the foregoing. Computer-readable storage media, as used herein, are not to be construed as transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., optical pulses through fiber optic cables), or electrical signals transmitted through wires.

The computer readable program instructions described herein may be downloaded from a computer readable storage medium to a respective computing/processing device or to an external computer or external storage device over a network, such as the internet, a local area network, a wide area network, and/or a wireless network. The network may include copper transmission cables, fiber optic transmissions, wireless transmissions, routers, firewalls, switches, gateway computers and/or edge servers. The network interface card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium in the respective computing/processing device.

Computer program instructions for performing the operations of the present disclosure can be assembly instructions, instruction Set Architecture (ISA) instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, c++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program instructions may be executed entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computer (for example, through the Internet using an Internet service provider). In some embodiments, aspects of the present disclosure are implemented by personalizing electronic circuitry, such as programmable logic circuitry, field Programmable Gate Arrays (FPGAs), or Programmable Logic Arrays (PLAs), with state information of computer readable program instructions, which can execute the computer readable program instructions.

Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.

Claims (10)

1. An upward compatible voltage coordination control method for a large photovoltaic power station is characterized by comprising the following steps of:

the method comprises the following steps:

step 1, acquiring real-time values, upper limit values and lower limit values of grid-connected point voltages of a photovoltaic power station, real-time values, adjustable upper limit values and adjustable lower limit values of reactive power of a photovoltaic inverter and SVG, and calculating total reactive power shortage of the photovoltaic power station and total reactive power increase and decrease margin sum of the photovoltaic power station and SVG according to acquired data;

step 2, executing a reactive coordination control strategy based on the total reactive power shortage of the photovoltaic power station and the sum of reactive power increase and decrease margin of the photovoltaic power station and SVG, and adjusting the voltage of the grid-connected point of the photovoltaic power station to a preset normal range;

when the reactive coordination control strategy is executed, the time sequence of the cluster in the SVG and the photovoltaic power station participating in reactive coordination control is determined based on the capacity, the time interval of participating in regulation and fault information;

And 3, after the voltage is regulated to a preset normal range, carrying out voltage optimization and time sequence progressive control by taking the median of the upper and lower limits of the voltage as a target according to the voltage level of the grid-connected point of the current photovoltaic power station.

2. The method for upwardly compatible voltage coordination control of a large photovoltaic power plant of claim 1, wherein:

in the step 1, the total reactive power deficiency calculation formula of the photovoltaic power station is as follows:

in the formula, deltaQ _up 、ΔQ _dn The total reactive power shortage when the reactive power of the photovoltaic power station is increased and reduced respectively;

U _r 、U _up and U _dn Real-time value and upper and lower limit values of PCC voltage of a public connection point of a photovoltaic power station access power grid are respectively obtained;

s is the sensitivity of the photovoltaic power plant, SVG and static var compensator to PCC voltage.

3. The method for upwardly compatible voltage coordination control of a large photovoltaic power plant of claim 1, wherein:

in the step 1, the calculation formula of the sum of the reactive power increase and decrease margins of the photovoltaic power station and the SVG is as follows:

in the method, in the process of the invention,the sum of the reactive increase margin and the reactive decrease margin respectively represents reactive output capacity;

Q _{Xi_r} 、Q _{Xi_max} 、Q _{Xi_min} the real-time value, the adjustable upper limit and the adjustable lower limit of the reactive power of the ith photovoltaic inverter or SVG are respectively;

n is the number of photovoltaic inverters or SVGs;

subscript X takes G or SVG, representing photovoltaic power plant or SVG, respectively.

4. The method for upwardly compatible voltage coordination control of a large photovoltaic power plant of claim 1, wherein:

in the step 2, the strategy of reactive coordination control is as follows: based on the total reactive power shortage of the photovoltaic power station, the sum of reactive power increase and decrease margins of the photovoltaic power station and the SVG and a preset normal range threshold value, judging the following contents and determining the reactive power increase and decrease amount of the corresponding photovoltaic power station and SVG and the input capacity of the static reactive compensator so as to perform reactive coordination control: whether reactive power is increased or decreased, whether current output of SVG is non-negative/non-positive, whether a photovoltaic power station singly adjusts to meet voltage regulation requirement or not, whether the SVG and the photovoltaic power station can meet the voltage regulation requirement after being set to zero or not together with adjustment of the photovoltaic power station, whether the photovoltaic power station and the SVG keep maximum reactive power output to be adjusted together to meet the voltage regulation requirement or not, and whether a static reactive compensator meeting the voltage regulation condition can be found or not, wherein the time sequence of the SVG and the cluster in the photovoltaic power station participating in reactive power coordination control after the reactive power increase is determined based on capacity, time interval participating in adjustment and fault information.

5. The method for upward compatible voltage coordination control of a large photovoltaic power plant according to claim 1 or 4, wherein the method comprises the following steps:

in the step 2, the strategy of reactive coordination control specifically includes:

a) Judging whether to increase or decrease reactive power: according to the current grid-connected point voltage level of the photovoltaic power station, if the current grid-connected point voltage of the photovoltaic power station is lower than the lower threshold value of the preset normal range, the reactive power needs to be increased, and the method is changed into b) to continue to execute; if the voltage of the grid-connected point of the current photovoltaic power station is higher than the upper threshold value of the preset normal range, converting reactive power reduction into c) to continue to execute;

b) Adding reactive power, judging whether the current output of SVG is not negative: judging whether the current SVG is in a reactive state or a reactive state absorption state according to the SVG output value so as to execute a corresponding strategy; if the SVG output is not negative, converting to d) and continuing to execute; if the SVG output is negative, converting to e) and continuing to execute;

c) Subtracting reactive power, and judging whether the current output of SVG is not positive: judging whether the current SVG is in a reactive state or a reactive state absorption state according to the SVG output value so as to execute a corresponding strategy; if the SVG output is not positive, converting to f) and continuing to execute; if the SVG output is positive, turning to g) to continue execution;

d) SVG output is nonnegative, and whether the photovoltaic power station can meet the requirement by singly adjusting: reactive output capability of photovoltaic power stationAnd total reactive power deficiency delta Q _up Comparing and judging; if->The requirement can be met by independently adjusting the photovoltaic power station, and at the moment, the reactive power increment of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _up SVG reactive power output delta Q _SVG The current adjustment is finished and enters a round detection state; if->The photovoltaic power station and the SVG are all involved in regulation, and at the moment, the process goes to h) to continue to be executed;

e) SVG output is negative, and whether the reactive power deficiency photovoltaic power station can be supplemented after the SVG is increased to 0 is judged: absolute value of SVG current reactive value |Q _{SVG_r} Current reactive margin Q of photovoltaic _G ^ad And total reactive power deficiency delta Q _up Comparing and judging; if it isThen it may be satisfied that, at this time, the SVG reactive delta is: ΔQ _SVG ＝|Q _{SVG_r} The reactive increment of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _up -|Q _{SVG_r} The adjustment is finished, and a round detection state is entered; if it isFailing to meet, at this time, go to h) to continue execution;

f) If the SVG output is not positive, judging whether the independent regulation of the photovoltaic power station can meet the requirement: reactive output capability of photovoltaic power stationAnd reactive shortage delta Q _dn Comparing and judging; if->Then the photovoltaic power station can meet the requirement by being independently regulated, and at the moment, the reactive power reduction amount of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _dn SVG reactive power output delta Q _SVG The current adjustment is finished and enters a round detection state; if->The photovoltaic power station and the SVG are all involved in regulation, and at the moment, the process goes to i) to continue to be executed;

g) If the SVG output is positive, judging whether the reactive power deficiency photovoltaic power station can be supplemented after the SVG is reduced to 0: absolute value of current value of SVG |Q _{SVG_r} Current margin of i and photovoltaicSum and total reactive power deficiency Δq _dn Comparing and judging; if it isThen it may be satisfied that the SVG reactive power reduction is: ΔQ _SVG ＝|Q _{SVG_r} The reactive power reduction of the photovoltaic power station is as follows: ΔQ _G ＝ΔQ _dn -|Q _{SVG_r} The adjustment is finished, and a round detection state is entered; if it isFailing to meet, at this point, go to i) continue execution;

h) Judging whether the photovoltaic power station and the SVG can be regulated together with the maximum reactive power output to meet the voltage regulation requirement: reactive output margin of photovoltaic power stationSVG margin->Sum and reactive deficiency Δq _up Comparing and judging; if it isThen it can be satisfied that, at this point, the photovoltaic power plant reactive delta is: />SVG reactive power increment is:the adjustment is finished, and a round detection state is entered; if->Judging whether the static var compensator meeting the voltage regulation condition can be found and determining the static var compensator to be put intoThe power compensator updates the total reactive power deficiency according to the capacity of the input static reactive power compensator, and returns to a) until the voltage returns to the normal range;

i) Judging whether the photovoltaic power station and the SVG can be regulated together with the maximum reactive power output to meet the voltage regulation requirement: reactive output margin of photovoltaic power stationMargin->Sum and reactive deficiency Δq _dn Comparing and judging; if it isThen it can be satisfied that, at this point, the photovoltaic power plant reactive delta is: / >SVG reactive power increment is:the adjustment is finished, and a round detection state is entered; if->And judging whether the static var compensator meeting the voltage regulation condition can be found, determining the input static var compensator, updating the total reactive power deficiency according to the input static var compensator capacity, and returning to the step a) until the voltage returns to the normal range.

6. The method for upward compatible voltage coordination control of a large photovoltaic power plant according to claim 5, wherein the method comprises the following steps:

h) In the method, whether the static reactive compensator meeting the voltage regulation condition can be found or not is judged, the input static reactive compensator is determined, the total reactive deficiency is updated according to the input static reactive compensator capacity, the method returns to the a), and the specific process until the voltage returns to the normal range is as follows:

firstly judging whether the reactor is not withdrawn, if not, turning to I) to continue; if yes, go to II) continue to carry out;

i) No reactor is not withdrawn, and whether the capacitor C meeting the following conditions can be searched or not is judged _k1 ：

If C is searched _k1 Then put into capacitor C _k1 The method comprises the steps of carrying out a first treatment on the surface of the The required total reactive compensation amount deltaq is then determined _up Reset to DeltaQ _up -Q _Ck1 Returning to the step a) for next round of judgment until the voltage returns to the normal range;

if C is not searched _k1 Then it is determined whether or not the capacitor C satisfying the following condition can be searched _k2 ：

Q in _lim1 Step size limitation for increasing the maximum dead weight for a single time;

if C is searched _k2 Then throw in C _k2 After the adjustment is finished, entering a round detection state;

if C is not searched _k2 Then modify the criteriaThen continuously judging whether the capacitor C meeting the criterion can be searched _k3 Wherein Q is _lim2 For the modified step size limitation of single increment of maximum dead weight, lambda epsilon (a, b) is an adjustment coefficient, a=0.5, b<1 if C is searched _k3 Then throw in the C _k3 After the adjustment is finished, entering a round detection state; if C is not searched _k3 The reactive power increment of the photovoltaic power station is: /> SVG reactive power increment is: />Reactive deficiency is added again>Feeding back, after the adjustment is finished, and entering a round detection state;

II) if the reactor is not withdrawn, judging whether the reactor L meeting the following conditions can be searched _k1 ：

If search for L _k1 Then withdraw from the reactor L _k1 The method comprises the steps of carrying out a first treatment on the surface of the The required total reactive compensation amount deltaq is then determined _up Reset to DeltaQ _up -Q _Lk1 Substituting the voltage into the a) to perform the next round of judgment until the voltage returns to the normal range;

if not find L _k1 Then, it is determined whether or not the reactor L satisfying the following conditions can be searched _k2 ：

If search for L _k2 Exit L _k2 After the adjustment is finished, entering a round detection state;

If not find L _k2 Then modify the criteriaThen continuously judging whether the reactor L meeting the following conditions can be searched _k3 Wherein lambda E (a, b) is the upper limit adjustment coefficient,a＝0.5，b<1 if search for L _k3 Exit L _k3 After the adjustment is finished, entering a round detection state; if not, go to I) perform the adjustment.

7. The method for upwardly compatible voltage coordination control of a large photovoltaic power plant of claim 1, wherein:

in step 2, the time sequence of the cluster participating in reactive coordination control in the photovoltaic power station is determined based on the capacity, the time interval of participating in regulation and fault information, and specifically:

different collector wires and subordinate modules in the photovoltaic power station are regarded as different photovoltaic clusters, and the time sequences of the different clusters participating in reactive coordination control are as follows:

OP＝sort{PRI _i }

in the formula, OP is a time schedule of different clusters participating in reactive coordination control;

PRI _i for the priority of cluster i, the calculation is as follows:

in CS _i Is the capacity size factor of cluster i;

Q _i reactive margin for cluster i;

Δq is the total reactive power deficiency currently allocated to the photovoltaic power plant;

TI _i a time interval factor for cluster i;

T _0-i the time interval duration of the last participation adjustment of the cluster i is the distance;

T _max maximum time interval allowed for two adjacent participating adjustments of the cluster;

FF _i Is a fault factor;

N _i the number of times cluster i has failed;

N _sum the total times of faults of all clusters in the whole photovoltaic power station are counted;

OF _i is a shielding factor;

P _i the active power value of the current cluster i;

P _max the maximum value of active power in all current clusters is obtained;

PRI _i the larger the value is, the higher the priority is, the stronger the reliability of the appointed reactive power support is, and the reactive power distribution is participated preferentially.

8. The method for upward compatible voltage coordination control of a large photovoltaic power plant according to claim 7, wherein the method comprises the following steps:

in step 2, if a plurality of SVGs exist, removing shielding factors in a time sequence determination mode of the cluster in the photovoltaic power station for participating in reactive coordination control, and correspondingly mapping meanings of other variables into the SVGs to obtain time sequence priority of the SVGs for participating in reactive coordination control.

9. The method for upwardly compatible voltage coordination control of a large photovoltaic power plant of claim 1, wherein:

in step 3, the process is carried out by (U _up +U _dn ) And/2, searching whether a static reactive compensator meeting the following conditions exists or not for the optimization target:

if the voltage exists, the capacitor is put into or the reactor is withdrawn from by judging whether the DeltaQ sign is put into or withdrawn from the static var compensator, if DeltaQ is negative, the capacitor is put into or withdrawn from the reactor, and if DeltaQ is positive, the capacitor is withdrawn from or put into the reactor, so that the voltage is optimized;

Δq is the total reactive power deficiency currently allocated to the photovoltaic power plant;

the timing progression control is started when Δq satisfies the following condition:

when the time sequence is controlled in a progressive way, the reactive power progressive amount is as follows:

wherein x.epsilon. < -5,5 >.

The obtained DeltaQ _i After the progressive amount, ΔQ is used _i To update deltaq for voltage optimization.

10. A large photovoltaic power plant up-compatible voltage coordination control system for implementing the method of any one of claims 1-9, characterized by: the coordination control system includes:

the reactive power shortage and margin calculation module is used for acquiring real-time values, upper limit values and lower limit values of the voltage of the grid-connected point of the photovoltaic power station, real-time values, adjustable upper limit values and adjustable lower limit values of the reactive power of the photovoltaic inverter and the SVG, and calculating the total reactive power shortage of the photovoltaic power station and the sum of reactive power increase and decrease margins of the photovoltaic power station and the SVG according to the acquired data;

the reactive power coordination control module is used for executing a reactive power coordination control strategy based on the total reactive power shortage of the photovoltaic power station and the sum of reactive power increase and decrease margins of the photovoltaic power station and the SVG, and adjusting the voltage of the grid-connected point of the photovoltaic power station to a preset normal range;

when the reactive coordination control strategy is executed, the time sequence of the cluster in the SVG and the photovoltaic power station participating in reactive coordination control is determined based on the capacity, the time interval of participating in regulation and fault information;

And the voltage optimization and time sequence progressive control module is used for performing voltage optimization and time sequence progressive control by taking the upper and lower limit median values of the voltage as targets according to the voltage level of the grid-connected point of the current photovoltaic power station after the voltage is regulated to a preset normal range.