CN110571834B - Excitation top voltage optimal configuration method and system considering generator performance difference - Google Patents
Excitation top voltage optimal configuration method and system considering generator performance difference Download PDFInfo
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Abstract
The invention discloses an excitation top voltage optimal configuration method and system considering generator performance difference, wherein the method comprises the steps of grouping generators under an expected fault, and performing single-machine equivalence on a multi-machine system to obtain an equivalent power angle curve; performing excitation peak voltage increment disturbance, and calculating the adjustment performance index of each generator for system fault recovery; selecting the generator with the maximum regulation performance index for system fault recovery, completing one round of configuration of excitation peak voltage, judging whether a system stability performance improvement target is achieved, and if so, finishing the configuration; otherwise, judging whether the excitation top voltage of the updated generator is continuously increased by one disturbance step length to reach a preset configuration upper limit, if so, selecting the generator still having the excitation top voltage lifting margin to carry out the next configuration; otherwise, continuing to perform excitation peak voltage increment disturbance. The invention can realize the differentiated configuration of the excitation peak voltage of the generator, better improve the transient stability of the system and improve the transmission power of the regional tie line.
Description
Technical Field
The invention belongs to the technical field of power system stability control, and particularly relates to an excitation top voltage optimal configuration method and system considering generator performance difference.
Background
The generator excitation system plays an important role in improving the transient stability of the power system. The forced excitation emergency control of the generator is matched with an excitation system with high top voltage, so that the unit forced excitation function can be fully exerted, the generator can provide dynamic reactive power to the system in a short time after a power system fails, the output voltage of the generator is improved, the output electromagnetic power is increased, and the acceleration process of the unit after the failure is effectively inhibited. With the development of large units and large power grids, the requirement on the excitation forced excitation performance under the accident condition is improved. The excitation top voltage of the generator excitation system is a main index for determining the dynamic reactive power output capability of the generator excitation system, and the improvement of the excitation top voltage is beneficial to the transient stability of the system. However, the control effect of the forced excitation emergency control of the generator is usually limited due to the limitation of overvoltage and overcurrent capacity of the excitation main loop equipment, and the excitation top voltage cannot be increased without limit.
At present, some researches have been made to raise a given reference value of an excitation voltage within a certain period after a fault by adding forced excitation emergency control of a generator, so as to fully exert the forced excitation capability of the generator under a set excitation parameter. However, the emergency control of the generator by forced excitation usually can only exert a better control effect when the generator has a higher excitation top voltage, and when the excitation top voltage is insufficient or too low, the recovery of the generator terminal voltage of the generator is slower, and the emergency control by forced excitation even has no effect. Therefore, the reasonable configuration of the excitation top voltage of the generator is the premise that the forced excitation emergency control measures play a role.
How to reasonably configure the excitation peak voltage of the generator needs to be further researched, the existing traditional method generally adopts a homogenization idea, and excitation systems of the same type are generally designed with the same excitation peak voltage. When the excitation top voltage is designed by the homogenization method, the maximum regulation performance which can be exerted by the generator sets with the same type of excitation systems in the power grid system is set to be the same. However, only part of the critical generators are sensitive to fault disturbance during actual grid operation, and the set regulation performance can be fully exerted. Some non-critical generators inevitably have wasted performance due to being far from the fault, etc. Considering the difference of the adjustment performance actually exerted by different generators in the transient adjustment process after the fault disturbance, the research on differential control or design of differential parameters of the generators is very little. However, due to the fact that the distance between the generator and the fault position of the power system is far and near and the output power is different, the adjusting performance of different generators for system fault recovery under fault disturbance inevitably has difference, the excitation peak voltage of the generator is reasonably designed by considering the difference, and the transient stability of the system can be improved to a certain extent.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide an excitation top voltage optimal configuration method and system considering the performance difference of a generator, and aims to realize the configuration of the different excitation top voltages of generators with different performances and improve the transient stability of a power grid system.
To achieve the above object, according to an aspect of the present invention, there is provided an excitation top voltage optimal configuration method considering generator performance difference, including the steps of:
(1) grouping all the generators under the expected failure of the initial tide working condition, and performing single machine equivalence on a multi-machine system to obtain an equivalent power angle curve;
(2) performing excitation top voltage increment disturbance on the critical unit, and calculating the regulation performance index of each generator for system fault recovery according to the disturbed equivalent power angle curve;
(3) selecting a generator with the maximum regulation performance index for system fault recovery, updating the excitation top voltage of the generator, completing one round of configuration of the excitation top voltage, finishing the configuration if the system stability performance improvement target is completed, and outputting an excitation top voltage optimization configuration result; otherwise, judging whether the updated excitation top voltage is continuously increased by one disturbance step length to reach a preset configuration upper limit or not, and entering the step (4);
(4) if the updated excitation top voltage continues to increase one disturbance step length to reach the set configuration upper limit, selecting the generator with the excitation top voltage still having the improvement margin in the critical unit to perform the next round of configuration, and returning to the step (2); otherwise, go directly back to step (2).
Further, the step (1) specifically comprises:
(11) under the fault instability mode of the initial tide working condition, selecting the generators with the relative power angles exceeding 180 degrees to form a critical cluster according to the power angle curves of all the generators in the multi-machine system relative to the inertia center of the system, and forming the rest of the clusters by the rest of the generators;
(12) and (4) performing single machine equivalence on the multi-machine system, and obtaining an equivalent power angle curve according to the power angles of the critical machine group and the rest machine groups.
Further, the step (2) specifically comprises:
(21) performing excitation top voltage increment disturbance, and obtaining a power angle first swing maximum value according to a disturbed equivalent power angle curve;
(22) sequentially increasing the excitation peak voltage of each generator of the critical cluster by a disturbance step length;
(23) carrying out incremental disturbance on the equivalent power angle curve according to the excitation peak voltage to obtain the maximum value of the initial swing of the power angle after the incremental disturbance;
(24) and calculating the improvement amount of the excitation top voltage to the transient stability performance of the system according to the maximum value of the initial swing of the power angle before and after the excitation top voltage is subjected to incremental disturbance, and further obtaining the sensitivity of the maximum value of the initial swing of the system relative to the excitation top voltage as an adjustment performance index of the generator to the system fault recovery.
Further, the target of improving the system stability performance in the step (3) is that the reduction of the maximum value of the first swing of the equivalent power angle after the excitation top voltage is updated is greater than or equal to the expected value.
Further, if the next round of configuration is needed in step (4), the number of critical generators still having the excitation top voltage lifting margin is less than 1, and the configuration is ended.
According to another aspect of the present invention, there is provided an excitation top voltage optimal configuration system considering generator performance variation, including:
the unit grouping module is used for grouping fault units under the initial tide working condition, and performing single-machine equivalence on a multi-machine system to obtain an equivalent power angle curve;
the increment disturbance module is used for carrying out excitation top voltage increment disturbance and calculating the adjustment performance index of each generator for system fault recovery according to the disturbed equivalent power angle curve;
the first judgment module is used for judging whether to carry out next round of configuration or not through a system stability performance improvement target;
the second judgment module is used for judging whether the critical generator participates in the next round of configuration or not through the excitation top voltage upper limit;
and the optimal configuration output module is used for outputting an excitation top voltage optimal configuration result.
Preferably, the target for improving the system stability performance is that the reduction of the maximum value of the first swing of the equivalent power angle after the excitation top voltage is updated is greater than or equal to a desired value.
Through the technical scheme, compared with the prior art, the invention has the following beneficial effects:
1. the generator provided by the invention can quantitatively evaluate the index of the adjusting performance of the power system for fault recovery, and the single machine infinite equivalence of a multi-machine system is determined according to the grouping mode of the system, so that the transient stability of the multi-machine system can be simply and quantitatively analyzed based on the system disturbance track; the maximum value of the power angle curve of the equivalent single-machine infinite system directly represents the transient stability degree of the system, and the power angle instability of the multi-machine system shows that the equivalent power angle cannot be successfully returned to the normal range in the equivalent single-machine system; the dynamic reactive power output capability of the generator can be enhanced by increasing the excitation peak voltage of the generator, and the positive swing of the power angle of the system is effectively inhibited; the method has the advantages that the variation of the system equivalent power angle head swing maximum value after the excitation top voltage is subjected to incremental disturbance is calculated by adding the same numerical value on the basis of the initial values of different generators in sequence, so that the regulation performance of the different generators on the fault recovery of the power system can be correctly represented;
2. different from the traditional uniform design of generator excitation system parameters, the invention provides an excitation top voltage optimal configuration method considering the performance difference of the generator, and by optimizing the excitation top voltage of the critical cluster generator, the action effect of forced excitation emergency control of the generator can be ensured, the regulation performance of a key generator under expected faults can be utilized to a greater extent, and the transient stability of a power system is improved; according to the method, the dissimilarity of the regulation performances of different critical generators on fault recovery is researched, the generator with the best regulation performance is always selected to preferentially increase the excitation top voltage, the expected improvement amount of the system stability can be met at the cost of minimum excitation system modification, and compared with the traditional method that generator excitation parameters are uniformly configured, the method has better economic benefit;
3. the invention fully utilizes the disturbance track information of the power system, measures the regulation performance of the disturbance track information of different generators on system fault recovery according to the difference of the disturbance tracks of the different generators, has simple principle, good applicability to complex systems, and can meet the requirement of differentially designing the control parameters of the generators with precision.
Drawings
Fig. 1 is a schematic diagram of a modified 10-machine 39-node ac/dc hybrid system according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a simplified model of an excitation system equipped with a forced excitation emergency controller according to an embodiment of the present invention;
FIG. 3 is a flowchart of an excitation top voltage optimal configuration method considering generator performance differences according to the present invention;
fig. 4 is a power angle curve diagram of a generator inertia center coordinate system during system fault instability according to an embodiment of the present invention;
fig. 5(a) is a comparison diagram of power angle curves of different excitation top voltages of the critical unit configured in the power flow mode 1 according to the embodiment of the present invention;
fig. 5(b) is a comparison diagram of power angle curves of different excitation top voltages of the critical unit configured in the power flow mode 2 according to the embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention provides an excitation top voltage optimal configuration method and system considering generator performance difference, wherein the control effect of the forced excitation emergency control of a generator is ensured by differentially configuring the excitation top voltage of a critical generator in an MATLAB/Simulink system based on a modified 10-machine 39-node alternating-current and direct-current hybrid system. The transient stability of the system under fault disturbance under different excitation top voltage configuration schemes is compared in a simulation mode, so that the effectiveness of improving the transient stability of the system by the excitation top voltage optimal configuration method considering the performance difference of the generator is verified, and the transmission power of the regional tie line is improved.
A modified 10-machine 39-node alternating-current and direct-current hybrid system is shown in fig. 1, and the system is formed by transforming 16-15 lines into a high-voltage direct-current transmission line (a No. 16 bus is a high-voltage bus of a rectifier-side converter transformer, and a No. 15 bus is a high-voltage bus of an inverter-side converter transformer) on the basis of an IEEE10 machine 39-node system. The generator uses a fourth-order model, and the load models all adopt simple constant impedance models. The high voltage direct current adopts a quasi-steady state model commonly used in electromechanical transient simulation. The excitation system adopts a static self-shunt excitation system which has higher top voltage and can generate negative voltage by inversion, and is provided with a forced excitation emergency controller, and a simplified model of the system is shown in figure 2.
The invention provides an excitation top voltage optimal configuration method considering generator performance difference, a calculation flow chart is shown in figure 3, and the method comprises the following steps:
(1) selecting an initial value trend working condition, determining the grouping of expected failure units, and performing single-machine equivalence on a multi-machine system;
(11) selecting the initial tide working condition as follows: the steady state output of 10 generators is 430MW, 542.9MW, 540MW, 560MW, 580MW, 620MW, 455.7MW respectively, and the power flow of the line 21-16 is 424.3 MW. The initial excitation peak voltage of all generators in the system is conservatively set to be 4p.u., and the voltage reference value is 100V. And (3) carrying out fault scanning on the modified 10-machine 39-node alternating current-direct current hybrid system, and determining that the expected faults which easily cause the transient stability problem of the system are as follows: three-phase permanent ground faults occur at the positions, close to the bus 21, of the transmission lines 21-16 on the rectification side of the high-voltage direct-current transmission system;
(12) when a fault line is cut off within 0.25s, the system is stable; the fault clearing time is prolonged to 0.35s, and the power angle curve of each generator in the inertia center coordinate system is shown in fig. 4. As can be seen from fig. 4, the generators No. 4, 5, 6 and 7 are relatively fast forward swinging relative to the rest of the units and finally unstable;
(13) according to a power angle curve under an inertia center coordinate system of each generator when a fault is unstable, the relative power angles of the generators 4, 5, 6 and 7 exceed 180 degrees, the 4 generators together form a critical cluster (S cluster) under the fault, the rest generators 1, 2, 3, 8, 9 and 10 form the rest cluster (A cluster), and the excitation peak voltages of the generators 4, 5, 6 and 7 are considered to be optimally configured;
(14) according to the formula respectively
And
calculating equivalent inertia time constants, power angles, mechanical power and electromagnetic power of the critical cluster and the rest clusters;
(15) according to the formula ═S-ACalculating an equivalent power angle of the equivalent single-machine system,SandArespectively representing equivalent power angles of the critical cluster and the rest clusters; when a fault line is cut off in 0.25s, the maximum value of the first swing of the equivalent power angle of the system is 113.20 degrees; if the fault line is cut off in 0.33s, the maximum value of the first swing of the equivalent power angle of the system is 178.5 degrees, the instability of the system is increased when the fault line is cut off, and 0.33s is the initial valueLimit cut-off time in the excitation configuration.
(2) Determining parameters required by excitation top voltage optimization configuration calculation, wherein the parameters comprise: determining an increment step size Delta E of an excitation top voltage optimization configurationfmAn upper limit E is set to the excitation top voltage of the generator 1p.uMAX7p.u. and expected value delta of reduction of maximum value of first swing of equivalent power angle of system after excitation top voltage is optimally configuredudesire＝12°；
(3) Performing excitation top voltage increment disturbance under the initial excitation top voltage configuration condition, and calculating the regulation performance index of the critical generator for system fault recovery;
(31) according to the excitation peak voltage of the critical generator at the initial value Efmi0Equivalent power angle curve under 4p.ut(Efmi0) Recording the maximum value of the power angle headu(Efmi0)＝113.20°；
(32) Taking 1, 2, 3 and 4 as the reference, respectively corresponding to No. 4, No. 5, No. 6 and No. 7 generators, and sequentially setting the excitation peak voltage of each generator from an initial value Efmi0Is increased by (E)fmi0+ΔEfm) If the fault condition is not changed, carrying out simulation calculation;
(33) system equivalent power angle curve after incremental disturbance according to excitation peak voltaget(Efmi0+ΔEfm) Recording the maximum value of the first swing of the equivalent power angle after incremental disturbance is respectively carried out on the excitation top voltage of 4 critical generators as follows:u(Efm10+ΔEfm)＝111.5°，u(Efm20+ΔEfm)＝112.28°，u(Efm30+ΔEfm)＝112.41°，u(Efm40+ΔEfm)＝111.07°。
(34) according to the maximum value of the first pendulum of the equivalent power angle of the system before and after incremental disturbance of the excitation peak voltage, according to a formula deltaui＝u(Efmi0)-u(Efmi0+ΔEfm) Calculating the improvement amount of the excitation peak voltage increase on the transient stability performance of the system, wherein the results are respectively as follows: deltau1＝1.7°，Δu2＝0.82°，Δu3＝0.69°，Δu4＝1.13°；
(35) The disturbance increment of the excitation peak voltage of each generator is 1p.u., according to a formula
The sensitivity value of the maximum value of the head swing of the system relative to the excitation top value voltage is calculated to be equal to deltaui；
(4) Selecting a generator with the maximum regulation performance index for system fault recovery, updating the excitation top voltage of the generator, completing one round of configuration of the excitation top voltage, and determining whether the next round of configuration is needed according to a stability performance improvement target;
(41) according to the calculation result of the regulation performance index of the critical generator for system fault recovery, the regulation performance index mu of the No. 4 generator (namely the 1 st generator in the critical cluster, which is marked as the critical generator 1) is calculatediMaximum, according to formula Efmi＝Efmi0+ΔEfmUpdating the excitation peak voltage of the critical generator 1, i.e. commanding Efm1Completing one-round configuration of the excitation top voltage of the critical generator 1;
(42) equivalent power angle reduction delta after updating excitation peak voltage of critical generator 1u1.7 deg. due to deltau＜ΔudesireThen, the excitation top voltage of the next round needs to be optimally configured, and the updated excitation top voltage of the critical generator 1 is used as the initial excitation top voltage for configuring the generator of the next round, i.e. according to the formula Efm10＝Efm1Determining an excitation top voltage initial value of the critical generator 1 in the next round of configuration;
(5) judging whether the next round of configuration of the excitation top voltage of each unit reaches a set configuration upper limit or not, and determining a generator which needs excitation top voltage increment disturbance in the next round of configuration;
(51) according to the updated excitation top voltage configuration value E of the critical generator 1fm1E.u. 5p.u., calculate Efm1+ΔEfm＝6p.u.；
(52) According to Efm1+ΔEfm≤EMAXNext one isDuring wheel configuration, the excitation top voltage of the critical generator 1 still has a lifting margin, incremental disturbance is continuously considered to be carried out on the excitation top voltage of the critical generator 1, and the total number n of the critical group generators s4 remains unchanged.
(6) And (5) repeating the steps (3) to (5), wherein the calculation process of the excitation top voltage optimal configuration of the critical generator is shown in the table 1. As can be seen from table 1, when the first 3 rounds of configuration are performed, the adjustment performance index values of the critical generator 1 for fault recovery are all kept to be the highest, and the excitation top voltage of the critical generator 1 reaches the configuration upper limit through increasing the excitation top voltage for 3 times. Therefore, the excitation top value of the critical generator 1 is determined to be 7p.u. no longer changed in the following configuration runs. In the subsequent calculation, only excitation top voltage increment disturbance calculation needs to be carried out on the rest 3 critical units. Through 5 total calculations, the maximum value of the first swing of the equivalent power angle of the system under the expected fault is reduced to 99.82 degrees, and the improvement quantity delta of the transient stability performance of the system caused by the increase of the excitation top voltage is calculatedu113.2 ° -99.82 ° -13.38 °, depending on Δu≥ΔudesireAnd finally determining that the excitation top voltage of the critical unit is configured as follows: efm4＝7p.u.Efm5＝4p.u.Efm6＝4p.u.Efm7The procedure ends, 5p.u.
TABLE 1
Under three different excitation top voltage configuration schemes, the calculation results of the maximum value of the first swing of the equivalent power angle of the system when the fault line is cut off in 0.25s are shown in table 2. The scheme 1 is optimized configuration which is obtained by calculation and takes the difference of the adjusting performance of the generator into consideration, the schemes 2 and 3 are both configured in a comparison mode, the excitation top voltage of the machine 5 and the machine 6 with poor adjusting performance of the generator is equivalently improved in the scheme 2, the difference of the adjusting performance of different generators for fault recovery is not taken into consideration in the scheme 3, and the excitation top voltage is improved and modified uniformly according to a homogenization idea.
TABLE 2
From the results in table 2, it can be seen that under the excitation peak voltage configuration scheme calculated by the invention, the maximum value of the first swing of the equivalent power angle of the system under the same expected fault is the minimum, and the transient stability of the system is the best. In contrast, in the case of the scheme 2, when the excitation top value is improved in a unit with poor regulation performance, the improvement effect on the transient stability of the system is not better than that in the scheme 3 without considering the unit regulation performance difference, which shows that the method for optimally configuring the excitation top values according to the fault recovery regulation performance index value sequence of the generator is reasonable and necessary, and can maximally improve the transient stability of the system at the minimum excitation system modification cost.
The calculation results of the limit cut-off time for the system to maintain transient stability under an expected fault under three different excitation top voltage configurations are shown in table 3. The maximum limit removal time of the scheme 1, the maximum limit removal time of the scheme 3 times and the minimum limit removal time of the scheme 2 show that the transient stability of the system is the best after considering the performance difference of the generator and correctly configuring the excitation top value, and the transient stability is consistent with the analysis conclusion of the table 2, but the sensitivity of the limit removal time relative to the excitation top value voltage is strongly related to the power flow of the fault line, the sensitivity value is very small under the power flow of the present example, and the limit removal times of the schemes 1 and 3 are very close to each other, so that the limit removal time index is inconvenient to be used for guiding the excitation top value optimization configuration, but is suitable for verifying the effectiveness of.
TABLE 3
| Configuration scheme | 1 (differentiation) | 2 | 3 (homogenization) |
| Limiting ablation time/s | 0.391 | 0.370 | 0.385 |
Considering the 0.2s cut-off fault, table 4 compares the power delivered by the area tie 16-17 in the two power flow modes when the excitation top voltage is configured in case of the scheme 3 and the scheme 1. If the critical machine excitation peak voltage is uniformly configured according to the configuration scheme 3, the output of the critical machine set is adjusted to obtain a tide mode 1, and the transmission power of a connecting line 16-17 is 970.43 MW; and (3) differentially configuring the excitation peak voltage of the critical machine according to the configuration scheme 1, adjusting the output of the critical machine to obtain a tide mode 2, and increasing the transmission power of the connecting line 16-17 to 1027.17 MW. After the excitation top voltage is configured according to the adjustment performance differentiation of the generator, the transmission power of the regional tie line of the power grid is improved by 5.85%.
TABLE 4
In the two power flow modes shown in table 4, the excitation top voltage is configured according to the scheme 1 and the scheme 3, and when a fault line is expected to be cut off within 0.2s under a fault, the equivalent power angle curves of the system are shown in fig. 5(a) and 5 (b). As can be seen from fig. 5(a), compared with the uniform configuration in the scheme 3, in the differential excitation configuration in the scheme 1, the maximum value of the first swing of the equivalent power angle of the system is smaller, and the system has a larger transient stability margin. As can be seen from fig. 5(b), if the excitation top voltages of 4 critical machine groups are all set to 5.25p.u according to the scheme 3, the system is unstable due to the insufficient adjustment performance of the whole critical machine group under the expected failure. And when 4 critical unit excitation top voltage are configured according to the scheme 1 in a differentiated mode, the maximum value of the first swing of the equivalent power angle of the system under the expected fault is 166.7 degrees, and transient stability is still kept.
(1) Grouping the generators under the condition of expected failure of the initial tide working condition, and performing single machine equivalence on a multi-machine system to obtain an equivalent power angle curvet(Efmi0) Recording maximum value of power angle head swingu(Efmi0)；
(2) Performing excitation top voltage increment disturbance on the critical unit, and calculating the regulation performance index of each generator for system fault recovery according to the disturbed equivalent power angle curve;
(3) selecting a generator with the maximum regulation performance index for system fault recovery, updating the excitation top voltage of the generator, completing one round of configuration of the excitation top voltage, finishing the configuration if the system stability performance improvement target is completed, and outputting an excitation top voltage optimization configuration result; otherwise, judging whether the updated excitation top voltage is continuously increased by one disturbance step length to reach a preset configuration upper limit EMAXEntering the step (4);
(4) if the updated excitation top voltage continues to increase one disturbance step length to reach the set configuration upper limit, selecting the critical generator still having the excitation top voltage lifting margin to perform the next round of configuration, and returning to the step (2); otherwise, go directly back to step (2).
In this embodiment, first, a fault scan is performed on an actual grid system, an expected fault which is likely to cause a transient stability problem of the system is determined, a fault clearing time is determined, and if the system can maintain transient stability in the selected fault clearing time, the fault clearing time is increased until the system is unstable.
Specifically, the step (1) specifically includes:
(11) under the expected failure of the initial tide working condition, selecting the generators with the relative power angles exceeding 180 degrees to form a critical cluster according to the power angle curves of all the generators in the multi-machine system relative to the inertia center of the system, and forming the rest clusters by the rest generators;
(12) performing single machine equivalence on a multi-machine system, and obtaining power angles according to a critical machine group and the rest machine groupsEquivalent power angle curvet(Efmi0) Obtaining the maximum value of the power angle head swingu(Efmi0)。
According to the formula respectively
And
calculating equivalent inertia time constants, power angles, mechanical power and electromagnetic power of the critical cluster and the rest clusters; wherein M, PmAnd PeRespectively, the inertial time constant, power angle, mechanical power and electromagnetic power, and the subscripts S and a respectively represent the critical cluster and the remaining cluster.
Then according to the formula ═S-ACalculating an equivalent power angle of the equivalent single-machine system,SandArespectively representing the equivalent power angles of the critical cluster and the rest clusters.
Specifically, the step (2) specifically includes:
(21) performing excitation top voltage increment disturbance with increment disturbance step length of delta EfmSequentially setting the excitation peak voltage of each generator of the critical cluster from an initial value Efmi0Is increased by (E)fmi0+ΔEfm)，i＝1，2，…，ns，nsThe total number of the generators of the critical cluster;
(22) according to the disturbed equivalent power angle curvet(Efmi0+ΔEfm) Obtaining the maximum value of the initial pendulum of the power angle after the increment disturbanceu(Efmi0+ΔEfm)；
(23) The maximum value of the initial swing of the power angle before and after incremental disturbance according to the excitation peak voltage is calculated according to a formula deltaui＝u(Efmi0)-u(Efmi0+ΔEfm) Calculating the improvement amount of the transient stability performance of the system due to the increase of the excitation top voltage, and further obtaining the sensitivity of the first swing maximum value of the system relative to the excitation top voltage
As a generator pair systemAnd adjusting performance index of fault recovery.
Further, the target of improving the system stability performance in the step (3) is that the reduction of the maximum value of the first swing of the equivalent power angle after the excitation top voltage is updated is greater than or equal to the expected value deltaudesire。
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (6)
1. An excitation top voltage optimal configuration method considering generator performance difference is characterized by comprising the following steps:
(1) grouping the generators under the expected fault, determining a critical cluster and a rest cluster, and performing single-machine equivalence on a multi-machine system to obtain an equivalent power angle curve;
(2) performing excitation top voltage increment disturbance on a critical unit, and calculating the adjustment performance index of each generator for system fault recovery according to the disturbed equivalent power angle curve, wherein the method specifically comprises the following steps:
(21) performing excitation top voltage increment disturbance, and sequentially increasing the excitation top voltage of each generator of the critical cluster by a disturbance step value;
(22) carrying out incremental disturbance on the equivalent power angle curve according to the excitation peak voltage to obtain the maximum value of the initial swing of the power angle after the incremental disturbance;
(23) calculating the improvement amount of the excitation top voltage to the transient stability performance of the system according to the maximum value of the initial swing of the power angle before and after the excitation top voltage is subjected to incremental disturbance, and further obtaining the sensitivity of the maximum value of the initial swing of the system relative to the excitation top voltage to be used as an adjustment performance index of the generator to the system fault recovery;
(3) selecting a generator with the maximum regulation performance index for system fault recovery, updating the excitation top voltage of the generator, completing one round of configuration of the excitation top voltage, finishing the configuration if the system stability performance improvement target is completed, and outputting an excitation top voltage optimization configuration result; otherwise, judging whether the updated excitation top voltage is continuously increased by one disturbance step length to reach a preset configuration upper limit or not, and entering the step (4);
(4) if the updated excitation top voltage continues to increase one disturbance step length to reach the set configuration upper limit, selecting the critical generator still having the excitation top voltage lifting margin to perform the next round of configuration, and returning to the step (2); otherwise, go directly back to step (2).
2. The excitation top voltage optimal configuration method according to claim 1, wherein the step (1) specifically comprises the following steps:
(11) under the expected failure of the initial tide working condition, selecting the generators with the relative power angles exceeding 180 degrees to form a critical cluster according to the power angle curves of all the generators in the multi-machine system relative to the inertia center of the system, and forming the rest clusters by the rest generators;
(12) and performing single machine equivalence on the multi-machine system, and obtaining an equivalent power angle curve according to the power angles of the critical machine group and the rest machine groups.
3. The excitation top voltage optimal configuration method according to claim 1, wherein the system stability improvement goal in step (3) is that a reduction amount of the maximum value of the first swing of the equivalent power angle after the excitation top voltage is updated is greater than or equal to a desired value.
4. The optimal configuration method of the excitation top voltage according to claim 1, wherein in the step (4), if the next configuration is needed, the number of critical generators having the excitation top voltage boosting margin is less than 1, and the configuration is ended.
5. An excitation top voltage optimal configuration system considering generator performance difference, comprising:
the unit grouping module is used for grouping the units under the condition of the expected failure of the initial tide working condition, and performing single-machine equivalence on a multi-machine system to obtain an equivalent power angle curve;
the increment disturbance module is used for carrying out excitation top voltage increment disturbance, calculating the adjustment performance index of each generator for system fault recovery according to the disturbed equivalent power angle curve, namely carrying out excitation top voltage increment disturbance, and sequentially increasing the excitation top voltage of each generator of the critical cluster by a disturbance step value; carrying out incremental disturbance on the equivalent power angle curve according to the excitation peak voltage to obtain the maximum value of the initial swing of the power angle after the incremental disturbance; calculating the improvement amount of the excitation top voltage to the transient stability performance of the system according to the maximum value of the initial swing of the power angle before and after the excitation top voltage is subjected to incremental disturbance, and further obtaining the sensitivity of the maximum value of the initial swing of the system relative to the excitation top voltage to be used as an adjustment performance index of the generator to the system fault recovery;
the first judgment module is used for judging whether to carry out next round of configuration or not through a system stability performance improvement target;
the second judgment module is used for judging whether the critical generator participates in the next round of configuration or not through the excitation top voltage upper limit;
and the optimal configuration output module is used for outputting an excitation top voltage optimal configuration result.
6. The excitation top voltage optimal configuration system according to claim 5, wherein the system stability improvement target is that a reduction amount of the maximum value of the first swing of the equivalent power angle after the excitation top voltage is updated is equal to or greater than a desired value.
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