Disclosure of Invention
The invention provides a loop parameter calculation method and a loop parameter calculation system for a high-voltage capacitive direct test, which solve the problems disclosed in the background technology.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a loop parameter calculation method for a high-voltage capacitive direct test comprises a loop parameter calculation method for a single capacitor bank switching test and a loop parameter calculation method for a back-to-back capacitor bank switching test;
the method for calculating the loop parameters of the opening and closing test of the single capacitor bank comprises the following specific steps:
responding to the on-off of the tested breaker, and constructing a relation model of the per unit voltage value and the time of the break of the tested breaker according to a test mode;
calculating the ratio K of the actual initial recovery voltage envelope curve to the undamped oscillation envelope curve according to the relation model, the straight line passing through the origin point tangent to the corresponding curve of the relation model and the horizontal line of the peak value of the overvoltage per unit value; wherein the voltage per unit value peak value is equal to the initial recovery voltage amplitude coefficient of the fracture of the tested breaker;
calculating the parameters of the open-close test loop of the single capacitor bank according to the K value;
the method for calculating the loop parameters of the back-to-back capacitor bank opening and closing test specifically comprises the following steps:
constructing a relation model of an inrush branch capacitor and a load branch capacitor according to the switching-off current, the standard recovery voltage peak value, the power frequency and the standard inrush frequency of the tested circuit breaker;
calculating the sum L of the initial inrush branch inductance and the load branch inductance according to the standard inrush frequency, the standard inrush peak value and the standard test voltage;
and calculating an inrush current branch capacitor, a load branch capacitor, a test loop equivalent power supply voltage, an inrush current damping resistor and an actual inrush current peak value according to the relation module and the L, adjusting the L according to a preset step length in response to that the actual inrush current peak value is not within a preset range, and repeating the step until the actual inrush current peak value is within the preset range to obtain back-to-back capacitor bank open-close test loop parameters.
The relation model of the fracture voltage per unit value of the tested breaker and the time is as follows,
wherein, ω is0For undamped angular frequency, ω for damped angular frequency, β for a variable defined in the calculation process, u1_d(t) is the per unit value of the fracture voltage of the tested breaker, t is time, R0、C0Respectively the resistance and capacitance in the frequency-modulated branch, LsIn order to test the equivalent inductance of the loop after the equivalence,
wherein, KTFor increasing the voltage to the ratio of the high-voltage side to the low-voltage side, LL、LHFor testing equivalent pre-boost of the loop to low-voltage side loop inductance and high-voltage side loop inductance, UgIs the power supply voltage, f is the power frequency, KcTo a capacitive coefficient, UrRated voltage for the circuit breaker under test, IcFor breaking the current of the circuit breaker under test, ktypeIn a test mode.
Calculating the ratio K of the actual initial recovery voltage envelope curve to the undamped oscillation envelope curve according to the relation model, the straight line passing through the origin point tangent to the corresponding curve of the relation model and the horizontal line of the peak value of the overvoltage per unit value,
according to the relation model, calculating the time t when the voltage per unit value reaches the peak valued_p;
Calculating td_pRatio K to undamped oscillation half period timeP1;
Acquiring tangent point coordinates of a corresponding curve of the relation model and a straight line passing through the origin;
acquiring intersection point coordinates of the straight line passing through the origin point and the peak horizontal line of the overvoltage per unit value according to the intersection point coordinates;
calculating the corresponding time and t of the intersection point coordinated_pRatio K ofP2;
According to KP1、KP2And calculating the ratio K of the actual initial recovery voltage envelope line to the undamped oscillation envelope line.
The test loop parameters comprise resistance and capacitance in the frequency modulation branch circuit, the calculation formula is as follows,
wherein L is
sFor testing equivalent inductance, R, after loop equivalence
0、C
0Respectively the resistance and capacitance in the frequency-modulated branch
Omega is the angular frequency with damping,
for variables defined in the calculation process, t
1The time corresponding to the envelope voltage value of the initial portion of the actual recovery voltage.
The relation model formula of the inrush branch circuit capacitance and the load branch circuit capacitance is as follows,
wherein, C2、C1Respectively a load branch circuit capacitor and an inrush current branch circuit capacitor, f is a power frequency, LsFor testing the equivalent inductance u after the loop is equivalentcsTo standard restore the voltage peak, IcFor the breaking current of the circuit breaker under test, fdsIs the standard inrush frequency.
The test loop parameters include the parameters of the test loop,
adjust to the last L;
introducing the adjusted final L into a relation model to obtain an inrush current branch capacitance and a load branch capacitance;
substituting the inrush branch capacitance and the load branch capacitance into an equivalent power supply calculation formula to obtain the equivalent power supply voltage of the test loop;
and introducing the adjusted L, the inrush branch capacitance and the load branch capacitance into an inrush damping calculation formula to obtain an inrush damping resistance.
An equivalent power supply calculation formula is obtained,
Us=UA-UA·2πf·(C1+C2)·2πf·Ls
wherein, UsFor testing the equivalent supply voltage of the loop, C2、C1Respectively a load branch circuit capacitor and an inrush current branch circuit capacitor, f is a power frequency, LsFor testing equivalent inductance, U, after loop equivalenceAThe voltage of an inrush current branch circuit when the tested breaker is closed;
the inrush current damping calculation formula is as follows,
wherein R is
dFor surge damping resistance, K
dIs a standard resistorDamping coefficient, parameter
A loop parameter calculation system for a high-voltage capacitive direct test comprises a loop parameter calculation system for a single capacitor bank opening and closing test and a loop parameter calculation system for a back-to-back capacitor bank opening and closing test;
the loop parameter calculation system for the opening and closing test of the single capacitor bank comprises,
a first relational model building module: responding to the on-off of the tested breaker, and constructing a relation model of the per unit voltage value and the time of the break of the tested breaker according to a test mode;
a K acquisition module: calculating the ratio K of the actual initial recovery voltage envelope curve to the undamped oscillation envelope curve according to the relation model, the straight line passing through the origin point tangent to the corresponding curve of the relation model and the horizontal line of the peak value of the overvoltage per unit value; wherein the voltage per unit value peak value is equal to the initial recovery voltage amplitude coefficient of the fracture of the tested breaker;
a test loop parameter acquisition module: and calculating the parameters of the open-close test loop of the single capacitor bank according to the K value.
The loop parameter calculation system for the back-to-back capacitor bank open-close test comprises,
a second relationship module construction module: constructing a relation model of an inrush branch capacitor and a load branch capacitor according to the switching-off current, the standard recovery voltage peak value, the power frequency and the standard inrush frequency of the tested circuit breaker;
an initial L acquisition module: calculating the sum L of the initial inrush branch inductance and the load branch inductance according to the standard inrush frequency, the standard inrush peak value and the standard test voltage;
an adjustment calculation module: and calculating an inrush current branch capacitor, a load branch capacitor, a test loop equivalent power supply voltage, an inrush current damping resistor and an actual inrush current peak value according to the relation module and the L, adjusting the L according to a preset step length in response to that the actual inrush current peak value is not within a preset range, and repeating the step until the actual inrush current peak value is within the preset range to obtain back-to-back capacitor bank open-close test loop parameters.
A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform a loop parameter calculation method of a high voltage capacitive direct test.
A computing device comprising one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising instructions for performing a loop parameter calculation method of a high voltage capacitive direct test.
The invention achieves the following beneficial effects: in the loop parameter calculation method for the single capacitor bank switching test, a relation model of a fracture voltage per unit value and time of the tested circuit breaker is established based on a test mode, and K values under different amplitude coefficients are calculated, so that frequency modulation branch parameters are calculated, envelope lines of initial parts of recovery voltages meet standard requirements, the calculation process and the calculation result are accurate, and manual adjustment is not needed; in the loop parameter calculation method for the back-to-back capacitor bank opening and closing test, the standard recovery voltage peak value, the inrush current damping resistance and the standard inrush current peak value are comprehensively considered, the calculation process and the calculation result are accurate, and manual adjustment is not needed.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
A loop parameter calculation method for a high-voltage capacitive direct test comprises a loop parameter calculation method for a single capacitor bank opening and closing test and a loop parameter calculation method for a back-to-back capacitor bank opening and closing test.
As shown in fig. 5, the method for calculating the loop parameters of the switching test of a single capacitor bank specifically includes the following steps:
step 1, responding to the on-off of the tested breaker, and constructing a relation model of the voltage per unit value of the break of the tested breaker and time according to a test mode.
The specific process of constructing the relationship model is as follows:
according to rated voltage U of Tested Breaker (TB)rOn/off current IcCalculation coefficient k corresponding to test modetypeAnd the initial recovery voltage amplitude coefficient K of the fracture of the tested circuit breakerafCalculating standard recovery voltage envelope parameters:
ucsfor standard recovery voltage peak:
t2stime corresponding to the standard recovery voltage peak:
t2snot only 8.7ms (50Hz) or 7.3ms (60Hz)
u1sFor the standard recovery voltage start part envelope voltage value:
t1sthe time corresponding to the envelope voltage value of the initial part of the standard recovery voltage is as follows:
t1s=constant
wherein, KcIs a coefficient of capacitance, t1sIs constant according to UrThe test mode is BC1 (test mode 1 for BC, current I is cut off)c10-40% of rated breaking current) ktypeThe test method is BC2 (test method 2 for BC, open current I) 1.98c100% or more of rated breaking current) ktype=1.95。
ucsAnd a supply voltage UgThe following formula should be satisfied:
wherein, KTFor step-up to T high-side to low-side ratio, LL、LHThe equivalent front boosting of a test loop is changed into a low-voltage side loop inductor and a high-voltage side loop inductor, and f is the frequency of a power frequency power supply.
KTAnd UgDetermined by the test station equipment parameters, at UgWithin an adjustable range of KTAs small as possible, the comprehensive consideration can result in KTAnd UgThen the equivalent power supply voltage U after the equivalent of the test loop can be calculatedsEquivalent inductance LsLoad electricityContainer C2:
Us=Ug·KT
Where ω is the damped angular frequency.
Calculating the parameters of the actual initial voltage envelope curve as follows:
wherein u is1For the actual recovery voltage starting part envelope voltage value, t1The time corresponding to the envelope voltage value of the initial portion of the actual recovery voltage.
After TB is switched off, the initial part of the voltage at both ends of TB is recovered from LsAnd its two-terminal voltage drop and frequency modulation branch (R)0-C0) And (3) parameter determination, namely deducing a relation model between the per unit voltage value of the fracture of the tested breaker and time:
wherein,
ω
0for undamped angular frequency, ω for damped angular frequency, β for a variable defined in the calculation process, u
1_d(t) is the per unit value of the fracture voltage of the tested breaker, t is time, R
0、C
0Respectively a resistor and a capacitor in the frequency modulation branch.
Step 2, calculating per unit according to the relation modelTime t at which value reaches peakd_p。
When ω td_pWhen 2 β, u1_d=KafIt can be derived that:
wherein, td_pIs the time per unit to peak.
Using zeroin numerical algorithm in
In-range finding
To solve for m, i.e.
β=tan
-1(m) then
Step 3, calculating td_pRatio K to undamped oscillation half period timeP1。
Due to the fact that
According to t
d_pThe first part of K can be obtained, i.e.
Wherein, t
0_pHalf-cycle time, parameter, for undamped oscillation
Omega is the angular frequency with damping,
are variables defined in the calculation process.
And 4, acquiring the coordinates of the tangent point of the corresponding curve of the relation model and the straight line passing through the origin.
Lines 1, lines 1 and u are defined as straight lines passing through the origin1_dAt time ttTangent, listing the equation gives:
m is obtained by calculation
Substituting the formula and making theta be omega.t
tThe following can be obtained:
t is found by solving the numerical solution n of theta in the range of theta ∈ (0, pi) by using a zeroin numerical algorithm, namely, the theta is equal to n
tN/ω, when the corresponding voltage per unit:
and 5, acquiring the intersection point coordinates of the straight line passing through the origin point and the per unit value peak horizontal line according to the tangent point coordinates.
Peak per unit value equal to K
afSpecifically, as shown in fig. 4, the intersection time of the straight line passing through the origin and the horizontal line passing through the per unit value peak is
I.e. the coordinates of the intersection point is (t)
c,K
af)。
Step 6, calculating the corresponding time of the intersection point coordinates and td_pTo obtain a second part of K, denoted as KP2。
Wherein, tc、u1_d_tRespectively corresponding time and tangent point coordinates to the intersection point coordinateCorresponding to the voltage per unit value.
Step 7, according to KP1、KP2Calculating the ratio K of the actual initial recovery voltage envelope to the undamped oscillation envelope, wherein K is KP1·KP2。
And 8, calculating the test loop parameters according to the K value.
The test loop parameters comprise resistance and capacitance in the frequency modulation branch, and the calculation formula is as follows:
wherein L is
sFor testing equivalent inductance, R, after loop equivalence
0、C
0Respectively the resistance and capacitance in the frequency-modulated branch
Omega is the angular frequency with damping,
for variables defined in the calculation process, t
1The time corresponding to the envelope voltage value of the initial portion of the actual recovery voltage.
Aiming at the parameter calculation of the opening and closing test of a single capacitor bank, the coefficient K under different amplitude coefficients is calculated by combining the second-order circuit analytical calculation and the calculation method of a Zeroin numerical algorithm, so that the frequency modulation branch parameter is calculated, and the envelope curve of the initial part of the recovery voltage meets the standard requirement. The calculation process and the calculation result are accurate, manual adjustment is not needed, and the parameter calculation can be rapidly realized in a programmable mode.
Aiming at the parameter calculation of the single capacitor bank opening and closing test, the voltage grade is subjected to per unit valuation, and the search of the tangent point can be independent of the voltage and only dependent on R0-Ls-C0Parameters and amplitude coefficients.
As shown in fig. 6, the method for calculating the loop parameters of the back-to-back capacitor bank open/close test specifically includes the following steps:
s1) constructing a relation model of the inrush branch circuit capacitance and the load branch circuit capacitance according to the on-off current, the standard recovery voltage peak value, the power frequency and the standard inrush current frequency of the tested circuit breaker.
The specific process of constructing the relationship model is as follows:
according to rated voltage U of Tested Breaker (TB)rOn/off current IcCalculation coefficient k corresponding to test modetypeAnd the initial recovery voltage amplitude coefficient K of the fracture of the tested circuit breakerafCalculating standard recovery voltage envelope parameters:
ucsfor standard recovery voltage peak:
t2stime corresponding to the standard recovery voltage peak:
t2snot only 8.7ms (50Hz) or 7.3ms (60Hz)
u1sFor the standard recovery voltage start part envelope voltage value:
t1sthe time corresponding to the envelope voltage value of the initial part of the standard recovery voltage is as follows:
t1s=constant
wherein, KcIs a coefficient of capacitance, t1sIs constant according to UrThe test mode is BC1 (test mode 1 for BC, current I is cut off)c10-40% of rated breaking current) ktypeThe test method is BC2 (test method 2 for BC, open current I) 1.98c100% or more of rated breaking current) ktype=1.95。
ucsAnd a supply voltage UgThe following formula should be satisfied:
wherein, KTFor step-up to T high-side to low-side ratio, LL、LHThe equivalent front boosting of a test loop is changed into a low-voltage side loop inductor and a high-voltage side loop inductor, and f is the frequency of a power frequency power supply.
K
TAnd U
gDetermined by the test station equipment parameters, at U
gWithin an adjustable range of K
TAs small as possible, the comprehensive consideration can result in K
TAnd U
g,C
1Relative to C
2Small and therefore generally does not affect K
TSelection of (2). Equivalent inductance can be calculated
Wherein C is
2、C
1Respectively, load branch circuit capacitance and inrush current branch circuit capacitance.
Determining the switching current IcStandard recovery voltage peak ucsAnd power frequency f, listing the following equation set:
UA=Us+UA·2πf·(C1+C2)·2πf·Ls
UA′=Us+UA′·2πf·C1·2πf·Ls
UA·ω·C2=Ic
wherein, UA、U′AThe inrush branch voltage when TB is closed and open, respectively.
The above equation is solved to obtain C2、C1The first equation of (1):
according to the standard inrush frequency fdsObtaining C2、C1Second equation of (1):
Wherein the parameters
L is an inrush current branch inductance L
1And load branch circuit inductance L
2Sum, i.e. L ═ L
1+L
2。
The first equation and the second equation form a relational model of the inrush branch capacitance and the load branch capacitance.
S2), calculating the sum L of the initial inrush branch inductance and the load branch inductance according to the standard inrush frequency, the standard inrush peak value and the standard test voltage.
Wherein the standard test voltage
I_f
dsIs the standard inrush peak.
S3), calculating an inrush current branch circuit capacitor, a load branch circuit capacitor, a test loop equivalent power supply voltage, an inrush current damping resistor and an actual inrush current peak value according to the relation module and the L, responding to the fact that the actual inrush current peak value is not located in a preset range, adjusting the L according to a preset step length, repeating the step until the actual inrush current peak value is located in the preset range, and obtaining back-to-back capacitor bank open-close test loop parameters.
Substituting L into the relationship model can solve C1By using C1Can solve out C2By using C2、C1Can solve out UA、U′ATest loop equivalent power supply voltage UsInrush damping resistance and actual inrush peak valueThe body is as follows:
Us=UA-UA·2πf·(C1+C2)·2πf·Ls
wherein R isdFor surge damping resistance, KdAs a standard damping coefficient, I _ fdIs the actual inrush peak.
The preset range is (I _ f)ds,1.02I_fds) Therefore, if I _ fd≤I_fdsAdjusting L, that is, L- Δ L is a preset step length, and may be adjusted as needed; if I _ fd≥1.02·I_fdsAnd adjusting L, namely L + Δ L, where Δ L is a preset step length.
The resulting experimental loop parameters include: 1. adjust to the last L; 2. introducing the adjusted final L into a relation model to obtain an inrush current branch capacitance and a load branch capacitance; 3. substituting the inrush branch capacitance and the load branch capacitance into an equivalent power supply calculation formula to obtain the equivalent power supply voltage of the test loop; 4. and introducing the adjusted L, the inrush branch capacitance and the load branch capacitance into an inrush damping calculation formula to obtain an inrush damping resistance.
The following example is made based on the above method: fig. 7 shows an example of simulation calculation of the opening and closing test of a single capacitor bank: u shaper=252kV,IcFrom the calculation results, it can be seen that the recovery voltage satisfies the envelope ucs-t2sThe initial part (amplification part) of the recovery voltage does not exceed u1s-t1sAnd the requirements are met. Fig. 8 is a calculation example of the back-to-back capacitor bank opening and closing test: u shaper=252kV,Ic1100A, peak inrush current I _ fd≥I_fds(I_fds20kA), inrush frequency fd=4348Hz(fds4250Hz), meets the requirements.
Aiming at the parameter calculation of the back-to-back capacitor bank switching test, an equation set related to inrush frequency, cut-off current, standard recovery voltage and loop principle is established to obtain C2、C1Expression of the relationship, C obtained thereby2、C1The parameters can be made to meet both the inrush frequency and the standard recovery voltage requirements.
Aiming at parameter calculation of back-to-back capacitor bank opening and closing test, initial L is given, and I _ f is reduceddThe calculation range of (2) shortens the calculation time and is beneficial to the realization of computer programming.
Aiming at parameter calculation of back-to-back capacitor bank opening and closing test, R is synchronously considered in the process of calculating test parametersdGiving out a calculation formula of the inrush current damping resistance to influence of inrush current attenuation, so that the inrush current waveform obtained by calculation automatically meets the standard damping coefficient Kd。
In conclusion, in the loop parameter calculation method for the single capacitor bank switching test, a relation model of the fracture voltage per unit value and time of the tested circuit breaker is established based on a test mode, and K values under different amplitude coefficients are calculated, so that frequency modulation branch parameters are calculated, the envelope curve of the initial part of the recovery voltage meets the standard requirement, the calculation process and the calculation result are accurate, and manual adjustment is not needed; in the loop parameter calculation method for the back-to-back capacitor bank opening and closing test, the standard recovery voltage peak value, the inrush damping resistance, the standard inrush current peak value and the frequency are comprehensively considered, the calculation process and the calculation result are accurate, and manual adjustment is not needed.
A loop parameter calculation system for a high-voltage capacitive direct test comprises a loop parameter calculation system for a single capacitor bank opening and closing test and a loop parameter calculation system for a back-to-back capacitor bank opening and closing test;
the loop parameter calculation system for the opening and closing test of the single capacitor bank comprises,
a first relational model building module: responding to the on-off of the tested breaker, and constructing a relation model of the per unit voltage value and the time of the break of the tested breaker according to a test mode;
a K acquisition module: calculating the ratio K of the actual initial recovery voltage envelope curve to the undamped oscillation envelope curve according to the relation model, the straight line passing through the origin point tangent to the corresponding curve of the relation model and the horizontal line of the peak value of the overvoltage per unit value; wherein the voltage per unit value peak value is equal to the initial recovery voltage amplitude coefficient of the fracture of the tested breaker;
a test loop parameter acquisition module: and calculating the parameters of the open-close test loop of the single capacitor bank according to the K value.
The loop parameter calculation system for the back-to-back capacitor bank open-close test comprises,
a second relationship module construction module: constructing a relation model of an inrush branch capacitor and a load branch capacitor according to the switching-off current, the standard recovery voltage peak value, the power frequency and the standard inrush frequency of the tested circuit breaker;
an initial L acquisition module: calculating the sum L of the initial inrush branch inductance and the load branch inductance according to the standard inrush frequency, the standard inrush peak value and the standard test voltage;
an adjustment calculation module: and calculating an inrush current branch capacitor, a load branch capacitor, a test loop equivalent power supply voltage, an inrush current damping resistor and an actual inrush current peak value according to the relation module and the L, adjusting the L according to a preset step length in response to that the actual inrush current peak value is not within a preset range, and repeating the step until the actual inrush current peak value is within the preset range to obtain back-to-back capacitor bank open-close test loop parameters.
A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform a loop parameter calculation method of a high voltage capacitive direct test.
A computing device comprising one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising instructions for performing a loop parameter calculation method of a high voltage capacitive direct test.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.