Background technology
Wind energy to increasing our energy supply, is adjusted China's energy resource structure and the positive role of having preserved the ecological environment as a kind of regenerative resource of cleaning.
Along with actively pushing forward of national generation of electricity by new energy, increasing large-scale wind electricity construction of base is finished, and solves the common recognition that the difficult problem of generation of electricity by new energy online has become people from all walks of life, and this has proposed new access problem for power grid construction.
But Chinese electric energy 2/3rds demands concentrate on eastern and central regions, and therefore, " three Norths " regional wind-powered electricity generation can't on-site elimination, need to rely on voltage levels, extensive remote the conveying.In addition, wind-powered electricity generation and thermoelectricity need to reach certain ratio, otherwise grid power transmission is difficult to bear.On the one hand, wind-electricity integration can cause that the electrical network quality of power supply descends, harmonic pollution, can cause the problem such as unstable of line voltage, frequency when Large Scale Wind Farm Integration is incorporated into the power networks.Because the unsteadiness of wind-powered electricity generation to still boneless electrical network formation impact of China, makes wind energy turbine set utilize hourage excessively low, can't form scale effect, causes Wind Power Project internal investment return rate to be lower than 8% social average level, lacks investment appeal.
Wind-driven generator be with wind as motive power, the stochastic volatility of wind and the intermittent output characteristic that has determined wind-driven generator also are fluctuations and intermittently.Wind-driven generator mostly is asynchronous generator, also will be from system's absorbing reactive power when sending active power, and its reactive requirement is to change with meritorious variation of exporting.When the capacity of wind energy turbine set hour, these characteristics are not remarkable on the impact of electric power system, but along with the increase of wind energy turbine set capacity proportion in system, wind energy turbine set will be more and more significant on the impact of system.The impact that extensive wind field is incorporated into the power networks on electrical network can be divided into two classes, and the one, on the impact of system's dynamic behaviour, comprise the impact of transient stability, voltage stabilization and electric harmonic etc.; The 2nd, the impact of grid dispatching management, comprise on the economy operation of power grid mode arrange, peak modulation capacity and on the impact of power grid accident processing etc.From China's wind-powered electricity generation survey report in 2008, Main Problems shows as:
One, large-scale wind power is incorporated into the power networks the quality of power supply and power system safety and stability influence on system operation is manifested
1) on the impact of mains frequency: wind energy turbine set depends on the wind energy turbine set Short circuit ratios to the impact of system frequency, i.e. wind energy turbine set rated capacity and the ratio of this wind energy turbine set with the capacity of short circuit of the tie point of electric power system.When short circuit ratio is larger, the stochastic volatility of Power Output for Wind Power Field on mains frequency to affect meeting more remarkable.
2) at present under the interconnected situation of large regional grid, the scale of electrical network is increasing, and wind energy turbine set is linked in the large system, and its capacity shared ratio in the total capacity of electrical network is very little, and is very little on the impact of the frequency of electrical network.But the connecting system, particularly regional grid of extensive wind field, it is to system frequency, comprises that the impact of the generation such as voltage fluctuation will become serious.
3) on the impact of the electrical network quality of power supply: the operation characteristic of the uncertainty of wind-resources and wind-powered electricity generation unit itself fluctuates the power output of wind-powered electricity generation unit, can affect the quality of power supply of electrical network, is mainly reflected in:
A) voltage fluctuation and flickering: voltage fluctuation and flickering are wind turbine generator to one of main negative effect of the electrical network quality of power supply.The grid connected wind power unit all can produce voltage fluctuation and flickering in continuous service and handover operation process.The factor that causes voltage fluctuation and flickering comprises that wind speed, wind turbine set type, control system and grid connected wind power unit points of common connection short circuit ratio and power network line X/R compare etc.;
B) harmonic pollution: the approach that harmonic wave produces in the wind power system comprises that mainly blower fan itself is equipped with the parallel capacitor of power electronic equipment and blower fan and the harmonic wave that line reactance generation resonance produces.Harmonic wave can cause the copper loss and the iron loss that increase generator, cause the phenomenons such as the heating accident of capacitor group and transformer, control circuit is influenced, sensor measurement is inaccurate in the wind power system.
4) on the impact of grid stability: wind-driven generator adopts induction machine more, and the operation of induction generator needs reactive power support.Although can improve power factor by dropping into reactive power compensator, the frequently delay on the switching life period certainly will produce threat to the voltage stabilization of grid-connected system.When the system voltage level reduced, the reactive power compensation amount descended a lot, and wind energy turbine set rises on the contrary to the reactive requirement of electrical network, further worsens voltage levvl, can cause voltage collapse when serious, and blower fan is by forced-stopping machine.In addition, the too high Voltage security margin that might reduce electrical network of output of wind electric field causes voltage collapse easily.Grid-connected wind farms is that fluctuation and the randomness of wind speed causes the output of wind electric field temporal evolution and is difficult to Accurate Prediction for the chief threat of grid stability on the one hand, and has potential potential safety hazard when causing the wind power generation connecting system.That the too high voltage stability that causes of wind-powered electricity generation injecting power reduces in the light current net on the other hand.
5) on the impact of grid relay protective apparatus: the trend of wind energy turbine set and electric power system interconnection is two-way sometimes, and this brings certain technical difficulty just for the protection configuration.The asynchronous generator that is incorporated into the power networks does not have independently excitation mechanism; when being short-circuited fault, significantly reduces owing to set end voltage in electrical network; wind-driven generator should possess certain low-voltage and keep ability; in the protection configuration, under-voltage protection should be set; before the under-voltage protection action; should reduce as far as possible no-power vacancy according to declaring accordingly apart from automatic switching reactive compensator, keep the stable operation of wind turbine generator.
Two, the wind power technology equipment is poor, and capacity for technological innovation is not enough
Three, wind-powered electricity generation operation and dispatching management are lacked experience
Technical standard is unsound: the technical standard of wind energy turbine set access electrical network need to be reformulated, to satisfy the requirement of wind energy turbine set fast development; The standard of the manufacturing of wind-powered electricity generation unit, detection and debugging aspect does not also form rounded system, and the relevant criterion of most key components and parts is not issue also; Most of wind-powered electricity generation unit power curve, the quality of power supply, meritorious and idle adjusting function, low voltage ride-through capability are through authentication.
In order to improve the ability that is incorporated into the power networks of wind energy turbine set, many emerging technologies and strategy continue to bring out, such as extensive energy storage device, wind power prediction, the meritorious idle coordination control of wind energy turbine set etc.Yet these technology all stand in local visual angle and for particular problem, are based upon on a series of basic assumptions, owing to lack the integrated planning to related link, the independent utilization of each technology all is difficult to play a role in practice.Therefore, a kind of total solution that contains wind-electricity integration links and correlation technique just becomes particularly important and necessary.
Summary of the invention
The purpose of this invention is to provide a kind of wind farm grid-connected coordination control method, to improve wind farm grid-connected ability, make wind energy turbine set integral body present operation and the modulating properties in traditional power plant for electrical network, minimizing is for impact and the impact of electrical network, and frequency modulation, pressure regulation and the safety and stability control of electrical network is provided support.
For achieving the above object, wind farm grid-connected coordination control method step of the present invention is as follows:
(1) gathers stand-alone device information in the wind energy turbine set, comprise running status and the technical characterictic parameter of blower fan, generator, transformer station, weather station relevant device;
(2) whole audience stand-alone device information and the on-the-spot wind power prediction information that gathers is gathered, carry out the generating capacity statistics;
(3) the on-the-spot wind power prediction of analysis-by-synthesis wind energy turbine set, maintenance scheduling and generating capacity statistical information generate the generating capacity plan, and with this generating capacity planning and scheduling wind power prediction information reporting to dispatching of power netwoks TSO;
(4) dispatching of power netwoks TSO selects accordingly meritorious, idle coordinated control mode according to the whole audience generating capacity plan that reports, the needs of the whole network operation and control;
(5) judge that according to the also site that gathers or points of common connection measured value electrical network is in normal stable state or accident condition;
(6) if be in steady operational status, then shield low voltage ride-through function, selected meritorious, idle control strategy is converted into wind energy turbine set meritorious, idle definite desired value of exerting oneself of particular moment; And desired value assigned the final controlling element to AGC/AVC, compared by surveying the value of exerting oneself with wind energy turbine set by energy storage control and the dispatch module of exerting oneself, according to the coordinated scheduling principle, be converted into the objectives value to each unit, energy storage device and reactive power compensator, and assign to each unit and equipment and carry out;
(7) if be in the power grid accident state, the then meritorious idle coordination control of shielding starts low voltage ride-through function, keeps set grid-connection.
Further, the field of described step (2) whole audience refers to the set corresponding to all units of same and site or points of common connection, belongs to same wind field or the cluster of a plurality of wind fields in organization.
Further, the generating capacity statistical information is according to on-the-spot wind power prediction in the described step (2), in conjunction with the technical characteristic of every Fans and equipment, determines the whole audience idle scope of exerting oneself of gaining merit.
Further, the repair and maintenance plan is to choose economic index or reliability index constitution optimization target according to on-the-spot wind power prediction, load prediction in the described step (3), determine the constraintss such as time, resource, seek the unit maintenance plan of feasible optimization, this unit maintenance plan in time circular is added up and the dispatch module of exerting oneself to generating capacity, so that add up generating capacity and assign the impact of getting rid of unit maintenance when exerting oneself.
Further, the generation of generating capacity plan is also planned according to the blower fan start and stop in the described step (3), this blower fan start and stop planning is the resource limitation according to resulting each the blower fan generating capacity of on-the-spot wind power prediction, and the prediction electrical network is to the power generation needs of wind energy turbine set, wind energy turbine set generating capacity statistics etc., load for certain level, solution allows the operation of which unit commitment, for one day load variations curve, and the how start and stop of each unit.
Further, meritorious coordinated control mode comprises in the described step (6):
Balance control a: steady state value is progressively raised or be adjusted downward to meritorious the exerting oneself of wind energy turbine set according to dispatch command;
Control for subsequent use: according to the meritorious ability of exerting oneself of maximum, wind energy turbine set is required the constant reserve capacity that keeps certain, in order to participate in frequency adjustment;
Restriction climbing rate: according to the technical indicator that electrical network is incorporated into the power networks, the restriction whole audience is meritorious exerts oneself with respect to the rate of change of time;
Congestion management: according to the plan of wind energy turbine set generating capacity, assign the meritorious instruction of exerting oneself and regulating to wind energy turbine set;
Utilize reserve capacity to carry out primary frequency modulation: the wind-powered electricity generation unit changes according to frequency change in such a way exerts oneself:
,
P T Be power of fan,
P Tdisp Be maximum generation power under the given wind speed,
P T0 Be power of fan under the rated frequency, s=5%;
If regard whole wind field as a generator, be the similar frequency characteristic of full blast field regulation:
Can according to the statistics of whole audience fan characteristic, convert out the frequency characteristic of wind field
K WF
The kinetic energy that utilizes blower fan to store carries out primary frequency modulation: the Kinetic Energy Calculation that blower fan stores is:
JBe fan rotor inertia,
Be its rotating speed;
Its inertia constant is:
,
SBe the specified apparent power of blower fan;
Frequency modulation frequency modulation: regulate meritorious exert oneself to reach regional balance and non differential regulation according to the instruction of scheduling, essence is to carry out to regulate specific meritorious instruction of exerting oneself.
Further, idle coordinated control mode comprises in the described step (6):
Specify idle output: the idle index of exerting oneself of appointment is directly assigned in scheduling to wind energy turbine set;
Automatism voltage control: according to the voltage indexes of appointment
V Ref , to the controlled busbar voltage of appointment
V Meas Detect, calculate idle the exerting oneself of the control required whole audience of voltage through comparing its difference
After obtaining voltage deviation, adopt idle coefficient of sensitivity to change in voltage
K Pv Determine reactive requirement;
, coefficient of sensitivity mainly determines by the area power grid that is connected with wind energy turbine set, can manually select or according to being calculated by two voltages and idle sampled point in the long term:
,
Then the required idle work variable quantity of voltage control is:
The whole audience is idle, and the index of exerting oneself is:
Control far-end load busbar voltage: according to the landing of the impedance estimation voltage of transmission line, and it is revised on the point voltage index that is incorporated into the power networks, with the voltage-regulation of this further back-up system:
, wherein
The voltage indexes of the controlled bus of far-end,
V Loss It is the voltage-drop that transmission line causes.
Further, described step (6) exert oneself assign comprise average assignment, in the ability ratio of can exerting oneself assign, in residue exert oneself that the ability ratio is assigned, the constant power factor is assigned, optimization is assigned, coordination assignment, the energy-storage system of dissimilar unit and reactive power compensator become with blower fan and starch coordination.
Further, described energy-storage system with become slurry coordinate be total active power of blower fan output through an one order inertia filter after as the desired value of energy storage control, meritorious through relatively getting difference as the output valve of energy-storage system with the actual output of blower fan, according to the time domain relation of each parameter, the control relational expression is as follows:
(1) establishes
tPower Output for Wind Power Field constantly
P Wind For
G (t), then
tConstantly level and smooth target
O 0 (t)Be calculated as follows:
O 0 (
t)
=α G(
t)+(
1-
α)
O 0 (
t-
1),
Wherein
α=1/ (1+
T/
Δ t) be the first-order filtering coefficient,
TBe time constant filter,
Δ tBe the sampling period;
(2)
tThe power output base value of energy-storage system is constantly:
H 0 (t)=
O 0 (
t)-
G(
t), on the occasion of being discharge, negative value is charging;
(3)
tActual blower fan and energy-storage system power output total amount are constantly:
O(
t)=
B (t)+
G(
t), wherein
B (t)For energy storage control system is accepted
H 0 (t)The power output order, energy-storage system real output after actual the execution,
O(
t) be
P Total tNumerical value constantly;
Blower variable blade control system is measured in the wind energy turbine set exit and is obtained
P Total (O(
t)
), itself and wind field appointment are exerted oneself
P Ref Relatively obtain to become the controlled quentity controlled variable that oar is regulated:
Δ P=P Ref -
P Total
Set limit value
P t , only have the ︱ of working as
Δ P︳ 〉
P t Pitch-controlled system just participates in regulating.
Further, described energy-storage system and blower fan become the slurry coordination
tThe power output of constantly assigning to energy-storage system
H(
t) correction of interpolation
H (t):
H(
t)=
H 0 (
t)+
h(
t); Correction
H (t)Expression formula be:
h(
t) =
A(
SOC –
αSOC -
m) =
A((1-
α)
SOC -
m) ,
Wherein
ABe feedback gain,
αBe inclination factor,
mFor the border correction by marginal ratio
MDetermine that SOC is battery charging state, the charge level of expression battery.
The present invention adopts the unique perspective for the treatment of wind energy turbine set from electrical network, according to three grades of frameworks of uniting coordination of blower fan, wind field and electrical network (machine, field, net), complete realization function and the intercoordination of each link at different levels, thereby make wind energy turbine set integral body present operation and the modulating properties in traditional power plant for electrical network, reduce it for impact and the impact of electrical network, even provide necessary support for the frequency modulation of electrical network, pressure regulation etc.The present invention stands in the angle of the overall situation and macroscopic view, support by modern communications and analytical calculation technical capability, utilize transverse integral (a plurality of unit equipment) and vertically joint coordination and the mutually support of whole (machine, field, net a plurality of control hierarchys), eliminate or reduce defective and the negative effect of blower fan individuality, thereby make wind energy turbine set integral body present friendly characteristic for electrical network, improve its hourage that is incorporated into the power networks, greatly increase economic efficiency.
Embodiment can be summarized as the planning of exerting oneself long a middle or short term shown in Figure 9.Dispatching of power netwoks sidepiece administration intelligent scheduling unit, wind energy turbine set are disposed meritorious cooperative control device AGC and the idle cooperative control device AVC of wind farm monitoring system and wind energy turbine set field deployment.The wind energy turbine set generating capacity plan that the intelligent scheduling unit of dispatching of power netwoks side reports by obtaining wind farm monitoring system, thermoelectricity plan among the functions such as wind power prediction, wind-powered electricity generation plan, maintenance scheduling and the traditional E MS, water power plan, Unit Combination, exchange plan, fuel planning, load prediction, automatic generation control etc. organically are combined into an integral body, and finally produce the planning of exerting oneself for a long time of wind energy turbine set.
Intelligent scheduling is assigned the planning of exerting oneself for a long time to wind farm monitoring system, rationally be decomposed into each unit output desired value through the dispatch module of exerting oneself, and according to SCADA communication cycle (second level) these desired values are assigned to AGC or AVC control device and to be carried out the planning of namely exerting oneself mid-term.According to actual wind field state, to same long-term planning value, can constantly adjust medium term planning, namely change each unit output desired value (second level), total amount is constant but the maintenance whole audience is exerted oneself.
AGC or AVC obtain the planning of exerting oneself mid-term of each unit, can directly carry out accordingly under normal condition.If but wind field generation short-term rapid change, and SCADA communication cycle long (second level), AGC and AVC can dynamically adjust each unit output desired value (Millisecond) according to actual conditions, but keep the whole audience total amount of exerting oneself constant, i.e. the short-term decision-making of exerting oneself.
One. wind farm monitoring system
Wind farm monitoring system is possessing on traditional data acquisition and the monitoring function basis, also needs to possess following functions: the collection of stand-alone device status data, wind power prediction, generating capacity statistics; Be described below respectively:
The stand-alone device status data gathers
The information gathering of stand-alone device, the running status and the technical characteristic parameter that comprise all relevant devices such as blower fan, generator, transformer station, weather station, such as rotation speed of fan, slurry elongation, generated power and reactive power, transformer state parameter and wind speed and temperature etc., gather to carry out further analyzing and processing by real-time data base.
On-the-spot wind power prediction
Carry out the wind power prediction at blower fan scene according to meteorological data, for example 24 hours wind power predictions or short-term wind power prediction are as input and the foundation of blower fan generating capacity statistics.
The generating capacity statistics
According to wind power prediction, in conjunction with the technical characteristic of every Fans and equipment, determine the whole audience idle scope of exerting oneself of gaining merit.As shown in Figure 3, physical technique characteristic according to blower fan, when blower fan meritorious exerted oneself when determining, it is idle exerts oneself to an interval should be arranged, these interval ranges are superposeed in meritorious rated value of exerting oneself, can obtain the zone (rated output scope) under the meritorious idle coordinate system as shown in Figure 3, such as solid line bar mark in Fig. 3 coordinate system.According to wind power prediction, specific time domain blower fan by the meritorious maximum magnitude of exerting oneself of wind power decision shown in dotted line in the figure coordinate system, then the zone under the dotted line is exactly that this blower fan is in the scope of exerting oneself (generating capacity) of specific time domain.The rated output scope of all units and prediction generating capacity gather rated output scope and the prediction generating capacity that forms a group of planes or wind field by statistics, form rated output scope and the generating capacity plan of final full blast field (group) through so step by step statistics, and report operation of power networks personnel TSO.TSO in conjunction with the wind field generating capacity statistics that reports, specifies the operating point (setpoint) of wind field according to the operation of power networks need analysis, and this operating point should be within the generating capacity plan area, as shown in Figure 3.In whole generating capacity statistic processes, to note following some:
-different types of blower fan, the regional profile of its rated output scope may be fully different with characteristics, and for example the doubly-fed variable-speed constant-frequency wind-driven generator has capacitive and the two-way idle regulating power of perception, and the constant speed induction machine does not just possess idle regulating power.
The regulating characteristics of-various dissimilar reactive power compensators also will be added up, and its idle regulating power also will be embodied in the scope of exerting oneself accordingly.
-because the wind energy turbine set zone is wide, the meritorious and reactive loss that its inner electrical network causes often can not be ignored, so the scope of exerting oneself of wind field and site need to be considered corresponding meritorious and reactive loss according to the structure of electrical network in the field.
Blower fan start and stop planning
Blower fan start and stop planning is similar to the Unit Combination of fired power generating unit, resource limitation according to resulting each the blower fan generating capacity of wind power prediction, and the prediction electrical network is to the power generation needs of wind energy turbine set, wind energy turbine set generating capacity statistics etc., load for certain level, which unit commitment solution allows to move, for one day load variations curve, the how start and stop of each unit.Its purpose is each unit of rational management, avoids the frequent start-stop of blower fan, prolongs its useful life.
The maintenance of fan maintenance plan
Choose economic index or reliability index constitution optimization target according to wind power prediction, load prediction, determine the constraintss such as time, resource, seek the unit maintenance plan of feasible optimization; The unit maintenance plan will in time be circulated a notice of to generating capacity statistics and the dispatch module of exerting oneself, so that add up generating capacity and assign the impact of getting rid of unit maintenance when exerting oneself.Can assess according to the load prediction of a certain period in future the demand of grid generation, determine repair time and the constraintss such as maintenance manpower and equipment, the optimization function of structure economic loss minimum is found the solution maintenance scheduling.
Two. final controlling element
Final controlling element mainly includes merit and coordinates control final controlling element (AGC) and idle cooperative control device (AVC), and the low voltage crossing final controlling element.
Final controlling element has main control unit and the actuator of oneself, and with the communication network of the stand-alone device such as blower fan, they can communicate and coordinated operation with wind farm monitoring system, but also can collect alone necessary data and information independent operating.Wherein, meritorious and idle coordination control final controlling element possesses the assignment of exerting oneself function, also has energy storage control function.Its function specifically describes as follows:
The assignment of exerting oneself
When the given wind field operating point of scheduling, or after the controlled quentity controlled variable of carrying out frequency and voltage adjustment converts the meritorious and idle index of exerting oneself to, its conversion need to be assigned as the desired value of exerting oneself of concrete each Fans or reactive power compensator.In fact the assignment of exerting oneself is exactly the inverse process of generating capacity statistics, the wind field that scheduling is specified or automatic control function the requires operating point of exerting oneself is decomposed and minute tasks each wind-powered electricity generation unit and reactive power compensator, this allocation process will be considered the running status of different units and the regulating power of device, and the economic index such as loss, so have corresponding various dispatching algorithm, system should provide following algorithms of different to supply user selection:.
A. on average assign
This is the simplest a kind of method of distribution, and it is equal that each blower fan meritorious and idle exerted oneself, and gets the mean value of whole audience gross capability:
(1)
nIt is the blower fan sum.The advantage of this method is Simple fast, but because not considering various constraintss, may cause the index of exerting oneself to exceed the unit output scope.
B. assign in the ability ratio of can exerting oneself
According to the pro rate of the meritorious idle ability of exerting oneself of each unit in wind field gross capability ability:
,
The meritorious and idle ability of exerting oneself for blower fan i;
,
Meritorious and the idle ability of exerting oneself for the whole audience.
C. assign in the residue ability ratio of exerting oneself
According to the pro rate of the remaining ability of exerting oneself of each unit, at first calculate the error between whole audience desired value and the measured value:
Error amount is assigned according to the exert oneself ratio of ability of residue between each unit as correcting value:
D. constant power factor apportionment exercise
When this method of salary distribution only limits to without the distribution of work, assign reactive power according to the ratio that active power distributes, so that the power factor of each unit equates:
Like this, the power factor of all units all equals:
E. optimization is assigned method
Optimization is assigned method according to the different target of optimizing and a correlative factor optimized target function of definition and a series of constraints that will consider.Optimization aim function for example:
(11)
This majorized function consists of by three, the gain merit error of desired value of the meritorious gross capability in first correspondence and site and the whole audience, exert oneself error with the idle desired value of exerting oneself of the whole audience that second correspondence and site are idle, the 3rd correspondence be the active loss that is caused by network loss.
p 1 ,
p 2 ,
p 3 Be weight coefficient, can adjust these weight coefficients to obtain different effects for different applied environments and target.
F. the coordination of dissimilar units and reactive power compensator is assigned
Carrying out idle exerting oneself when assigning, consider that the old-fashioned wind-driven generator of part may not possess idle regulating power of exerting oneself, and simultaneously other reactive power compensator may be installed, and the characteristics of exerting oneself of these compensation arrangements may be different, so relevant exerting oneself will be noted cooperation between the different reactive power sources when assigning.Can support mutually also between dissimilar units that for example double-fed constant frequency variable-speed generator (DFIG) can provide reactive power support to contiguous constant speed induction generator (FSIG).
Energy storage control system
Because the restriction of natural conditions, the variation of wind-force are often frequent violent, catch the wind-powered electricity generation unit that the maximal wind-energy mode is controlled according to tradition, its accordingly meritorious output also can produce the violent vibration of high frequency.And electrical network often limits the rate of change of meritorious output within the unit interval for wind farm grid-connected stipulations, even may specify total output of wind energy turbine set to remain unchanged in a certain period.If do not become the cooperation that oar is regulated, rely on energy-storage system to realize level and smooth and the tracking dispatch command fully, namely allow to realize that the capacity of required energy-storage system is very huge, and is with high costs.On the contrary, if only rely on the change oar to regulate level and smooth and the tracking dispatch command, because the wind wheel blade machinery inertial is huge, the scarce capacity of its reply high frequency power vibration.If energy storage is coordinated the division of labor with becoming oar, bring into play its willing advantage by energy-storage system and come the compensation power higher-order of oscillation, and remaining low frequency component is regulated reply by pitch-controlled system, but each most chief then.Because only need tackle the vibration of high fdrequency component, and need not long-time storage or discharge electric energy, the required capacity of energy-storage system can greatly reduce, and saves cost.Accordingly, because only needing the reply low frequency component, pitch-controlled system has also been avoided too frequently action, and regulating effect is good.
Be to realize that energy-storage system and blower fan become the coordination of starching, the deployment of energy storage control system as shown in Figure 6, its control block diagram as shown in Figure 7, the frequency-domain function of the transfer function of each link after with Laplace transformation represents among the figure.Total active power of blower fan output through an one order inertia filter after as the desired value of energy storage control, meritorious through relatively getting difference as the output valve of energy-storage system with the actual output of blower fan.According to the time domain of each parameter relation, control algolithm can be according to following relationship expression:
A. establish
tPower Output for Wind Power Field constantly
P Wind For
G (t), then
tConstantly level and smooth target
O 0 (t)Be calculated as follows:
O 0 (
t)
= αG(
t) + (
1-
α)
O 0 (
t-
1) (12)
Wherein
α=1/ (1+
T/
Δ t) be the first-order filtering coefficient,
TBe time constant filter,
Δ tBe the sampling period.
B.
tThe power output base value of energy-storage system is constantly:
H 0 (t) =
O 0 (
t) -
G(
t) (13)
On the occasion of being discharge, negative value is charging.
C.
tActual blower fan and energy-storage system power output total amount are constantly:
O(
t) =
B(t) +
G(
t) (14)
Wherein
B (t)For energy storage control system is accepted
H 0 (t)Energy-storage system real output after actual execution the after the power output order.As shown in Figure 6, we have
O(
t) be exactly
P Total tNumerical value constantly.
Blower variable blade control system is measured in the wind energy turbine set exit and is obtained
P Total (O(
t)
), itself and wind field appointment are exerted oneself
P Ref Relatively obtain to become the controlled quentity controlled variable that oar is regulated:
ΔP = P ref -
P total (15)
For preventing from becoming the frequent adjusting of oar, a limit value can be set judge link, set a limit value
P t , only have the ︱ of working as
Δ P︳ 〉
P t Pitch-controlled system just participates in regulating.
Control for energy-storage system, although provided the in theory power output of energy-storage system, but because the finite capacity of energy-storage system, it is also limited to discharge and recharge power, for guaranteeing the safety of battery system, SOC discharges and recharges the constraint that has bound, so according to the control block diagram of actual energy-storage system, its improvement is as follows:
tThe power output of constantly assigning to energy-storage system
H(
t) on formula (13) basis, add again a correction
H (t):
H(
t) =
H 0 (
t) +
h(
t) (16)
Correction
H (t)Expression formula be:
h(
t) =
A(
SOC –
αSOC -
m) =
A((1-
α)
SOC -
m) (17)
Wherein
ABe feedback gain,
αBe inclination factor,
mFor the border correction by marginal ratio
MDetermine.SOC (State Of Charge) is battery charging state, the charge level of expression battery.
The core concept of the method is in the level and smooth demand that discharges and recharges and keeps battery electric quantity to carry out balance between not out-of-limit, in the battery power output
H 0 (
t) on, according to correction of current state adding of battery electric quantity
h(
t).Briefly, be exactly when battery electric quantity the closer to upper in limited time, just many some electric energy of release than actual demand; When battery electric quantity the closer to lower in limited time, just many some electric energy of absorption than actual demand.Like this, so that battery electric quantity is between the upper lower limit value all the time in control procedure, the power of synthetic output can not produce unexpected vibration yet.
Among Fig. 8,
Y=SOCWith battery charge level
SOCEquivalent is mapped to
yOn the axle, and
Y=α SOC+mWith battery electric quantity state
SOCBe mapped to
yOn the axle
mArrive
E-mThe interval on, namely we wish the scope that battery electric quantity is not gone beyond.
tConstantly
SOCUnder the state,
Y=SOCWith
Y=α SOC+mBetween difference be exactly correction
h(
t).As seen from the figure, obviously,
h(
t) satisfy from
SOCThe upper limit is nearer on the occasion of larger, namely more discharges electric weight; From
SOCThe nearlyer negative value of lower limit is less, i.e. more store electrical energy.
Three. the intelligent scheduling unit
Be deployed in the intelligent scheduling unit of scheduling side, combine with traditional EMS, the function of wind power prediction, wind power generation plan, blower fan start and stop planning and maintenance of fan schedule module and traditional power-generating control system is organically combined, as shown in figure 10.Each functions of modules is described as follows:
The scheduling wind power prediction
This scheduling wind power prediction is and on-the-spot wind energy turbine set wind power prediction system independently mutually, be mainly used in generating capacity statistics that the verification wind energy turbine set reports and carry out the foundation of wind power generation plan and the planning of verification wind-powered electricity generation Unit Commitment as the intelligent scheduling unit, and participate in the iterative process of EMS generation schedule.Although hydrologic(al) prognosis belongs to medium term planning in EMS, because the particularity of wind energy, wind power prediction belongs to short-term planning, and reliable foundation need to be provided for the real time execution of system.
The meritorious coordination controlled
According to dispatching requirement, meritorious exerting oneself can be summarized as following several mode
A. balance control
A steady state value is progressively raised or be adjusted downward to balance control with meritorious the exerting oneself of wind energy turbine set according to dispatch command, as shown in Figure 4.
B. control for subsequent use
According to the meritorious ability of exerting oneself of maximum, wind energy turbine set is required the constant reserve capacity that keeps certain, in order to participate in frequency adjustment, as shown in Figure 5.
C. limit the climbing rate
According to the technical indicator (Grid codes) that electrical network is incorporated into the power networks, the restriction whole audience is meritorious exerts oneself with respect to the rate of change of time, in order to keep the balance of electric network source and load, avoids meritorious too fast fluctuation and concussion.
D. congestion management
Because the restriction of circuit transmission capacity, electrical network occur when congested, dispatching of power netwoks need to be exerted oneself and trend is regulated to power supply.According to the plan of wind energy turbine set generating capacity, assign the meritorious instruction of exerting oneself and regulating to wind energy turbine set.
E. utilize reserve capacity to carry out primary frequency modulation
Along with wind power generation constantly increases and alternative conventional synchronization generator in electric network source, the frequency regulation characteristics of electrical network inevitably changes.Similar to the primary frequency modulation of conventional synchronization generating set, the wind-powered electricity generation unit also can change according to frequency change in such a way exerts oneself:
P T Be power of fan,
P Tdisp Be maximum generation power under the given wind speed,
P T0 Be power of fan under the rated frequency, s=5%.
Similarly, if regard whole wind field as a generator, be the similar frequency characteristic of full blast field regulation:
Can according to the statistics of whole audience fan characteristic, convert out the frequency characteristic of wind field
K WF
According to the above whole audience that the calculates reference value of exerting oneself, distributes to each blower fan execution through exerting oneself.
F. the kinetic energy that utilizes blower fan to store carries out primary frequency modulation
Fall because losing suddenly the meritorious frequency that produces of supporting when the electrical network generation, blower fan can utilize the kinetic transformation of its rotating parts to exert oneself for meritorious, supports for electrical network provides of short duration (several seconds) to gain merit.The kinetic energy that blower fan stores may be calculated:
(21)
JBe fan rotor inertia,
Be its rotating speed.
Its inertia constant is:
SBe the specified apparent power of blower fan.
HCan roughly embody it only uses kinetic energy that the time of rated power is provided.
G. frequency modulation frequency modulation
Different from primary frequency modulation, frequency modulation frequency modulation need to be regulated meritorious exert oneself to reach regional balance and non differential regulation according to the instruction of scheduling, and its essence is exactly specifically meritorious instruction of exerting oneself of operation dispatching.
Idle coordination control
According to dispatching requirement, meritorious exerting oneself can be summarized as following several mode
A. specify idle output
The idle index of exerting oneself of appointment is directly assigned in scheduling to wind energy turbine set.
B. automatism voltage control
Automatism voltage control is according to the voltage indexes of appointment
V Ref , to the controlled busbar voltage of appointment
V Meas (being generally wind farm grid-connected point voltage) detected, and calculates idle the exerting oneself of the control required whole audience of voltage through comparing its difference
After obtaining voltage deviation, adopt idle coefficient of sensitivity to change in voltage
K Pv Determine reactive requirement.
Coefficient of sensitivity is mainly determined by the area power grid that is connected with wind energy turbine set, can manually select, also can be according to being calculated by two voltages and idle sampled point in the long term:
Then the required idle work variable quantity of voltage control is:
The whole audience is idle, and the index of exerting oneself is:
After obtaining the idle index of exerting oneself of the whole audience, consistent with the preamble narration via processes such as the dispatch module of exerting oneself again.
C. control far-end load busbar voltage
If be the control target take near the busbar voltage the far-end load, can be according to the landing of the impedance estimation voltage of transmission line, and it is revised on the point voltage index that is incorporated into the power networks, with the voltage-regulation of this further back-up system:
Wherein
The voltage indexes of the controlled bus of far-end,
V Loss It is the voltage-drop that transmission line causes.
The wind power generation plan
Wind power generation is intended to be a submodule of EMS generation schedule program, similar with the water power plan to the thermoelectricity plan, the generating capacity statistics that reports according to wind energy turbine set and the verification of scheduling wind power prediction, plan controllable power supply as a kind of, according to the plan characteristic of system loading prediction and other power supply, the generation schedulecurve that the responsibility that the grey iterative generation of process the whole network generation schedule and wind energy turbine set are born is corresponding.Because integrated each blower fan and the generating of equipment self and the Information Statistics of regulating power in this curve generation, the in addition coordinated scheduling of the on-the-spot final controlling element of wind energy turbine set, so that its execution has had abundant guarantee, system can not occur with the violent vibration of Plan Curve and depart from, thereby has reached the purpose that improves the wind energy turbine set power supply quality and improve the hourage that is incorporated into the power networks.