JP5378087B2 - System stabilization system with load compensation control function - Google Patents

Description

  The present invention relates to a frequency stabilization device and a control method for a power system, and in particular, when a generator connected to the power system is dropped, the load is cut off according to the drop of the generator, thereby The present invention relates to a power system frequency stabilization device and a control method for preventing frequency fluctuation.

  In the operation of the electric power system, when a generator dropout occurs, the supply and demand balance of the system becomes unbalanced, resulting in a frequency deviation. In order to eliminate this and stabilize the system frequency, it is necessary to quickly correct the supply-demand imbalance in the system. As a means for that, the load corresponding to the power generation amount of the generator that has dropped off is forcibly cut off. For this purpose, a system frequency stabilizing device for urgently performing load control in the system has been installed.

  In the conventional system, the system state is estimated based on the system information obtained as online data from each electric power station, and the load control amount for each generator is determined in advance in consideration of the generator characteristics and the instantaneous reserve capacity of the system. By calculating and cutting off the load, the supply and demand balance of the system is maintained and the frequency is stabilized.

  As a known example of this kind, Patent Document 1 is cited.

  Patent Document 2 discloses a power system stabilization device that performs stability determination at high speed when a system fault occurs.

Japanese Patent Laid-Open No. 10-32927 JP 2007-189840 A

  If the calculation is performed before the occurrence of the accident as in Patent Document 1, there is a possibility that the system state is changed when an actual system accident occurs. That is, a time delay occurs between the generator power generation amount used for calculation from online data obtained in advance and the generator power generation amount at the time of actual dropout, and the power generation amount is not necessarily the same. For this reason, due to the difference in the power generation amount of the generator, the control amount is not appropriate, and excess / deficiency control occurs. For this reason, there is a problem that, despite the control being performed, it deviates from the reference allowable frequency fluctuation value and the reference frequency point, and the system frequency is lowered or raised, causing disturbance.

  In addition, as in Patent Document 2, in order to perform stability determination at high speed when a system fault occurs, a computer having a large capacity is required, and such a large capacity computer must be prepared for each target power system. I can't.

  The problem to be solved by the present invention is to provide a power system frequency stabilization device and a control method therefor capable of realizing an appropriate control amount close to a real system within a range of appropriate equipment investment.

  The present invention estimates the state of the current system based on the system information obtained as sampling data in advance, and sets the load control amount to be executed when the generator is disconnected for each generator connected to the system. In the power system frequency stabilization device provided with the load control amount pre-calculating means for calculating the power control amount, the power generation amount comparing means for comparing the power generation amount of each generator adopted for the prior calculation of the load control amount with the power generation amount immediately before the accident And a load correction control amount calculation means for calculating an excess / deficiency load correction control amount with respect to the load control amount calculated in advance based on the output of the power generation amount comparison means, and the load control calculated in advance The main feature is that load control means for executing load control according to the amount and the load correction control amount is provided.

  According to a preferred embodiment of the present invention, by directly capturing the data immediately before the generator that has actually dropped out, it is possible to flexibly adapt to the state change of the generator power generation amount due to the time difference of the online data, and the allowable value. It is easy to maintain the frequency fluctuation within.

  In particular, it is possible to obtain an appropriate control amount by correcting only the difference in power generation amount with respect to the calculation result calculated from online data obtained in advance by correction control.

  In addition, since only the generator power generation amount is corrected, the calculation time is short, and appropriate control can be reliably performed without a control delay.

  Other objects and features of the present invention will be made clear in the embodiments described below.

1 is an overall configuration diagram of a power system frequency stabilization device according to an embodiment of the present invention. It is a control amount calculation figure calculated | required by the load control amount determination means by one Example of this invention. It is the fluctuation frequency locus diagram which maintained the allowable frequency fluctuation value calculated | required by the load control object determination means by one Example of this invention, and a reference frequency point. It is a whole block diagram of the electric power system frequency stabilization apparatus by the other Example of this invention. It is a figure of the posterior correction control locus | trajectory calculated | required from calculation of the posterior frequency locus | trajectory, and an actual frequency locus | trajectory, and a frequency change rate.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is an overall configuration diagram of a system frequency stabilizing device according to an embodiment of the present invention.

  In FIG. 1, a central system monitoring device 1 includes an online database 11 for storing online data, and a parameter database 12 for storing priority orders for interrupting loads in a wide range of power systems, operation set values such as generators, constants, and the like. It has. The data in the online database 11 and the data in the parameter database 12 are transmitted to the stabilization device 2 for each unit power system through transmission lines 111 and 121, respectively.

  Regarding the stabilization device 2, only load control based on pre-calculation using online data will be described first. The stabilization device 2 includes a system estimation unit 21, a load control amount determination unit 22, and a load control target determination unit 23 for load control based on pre-calculation, and a load control amount corresponding to the power generation amount of the dropout generator. Determine and output a load control command. The system estimation unit 21 estimates the current system from the online data, and the load control amount determination unit 22 calculates a load control amount corresponding to the power generation amount of each generator. Further, the load control target determining means 23 determines a target load combination that is optimal for frequency stabilization of the system.

  Generators 31 and 32 are installed in the power plant 3 connected to the grid 5. The power plant 3 transmits a drop command to drop from the system due to a system failure or a generator abnormality to the stabilization device 2 through the drop command transmission line 33. Loads 41 and 42 are installed at the substation 4 connected to the grid 5. The stabilization command is transmitted from the stabilization device 2 to the loads 41 and 42 in the substation 4 through the shutdown command transmission line 43. In the current configuration of the system 5, online data of the entire system is input to the central online database 11 through the transmission line 51.

  Next, the operation of the power system frequency stabilization device in the present embodiment will be described.

  First, the grid monitoring device 1 receives online data from the power grid 5 and periodically cycles the entire grid data such as the power generation amount of the generators 31 and 32 of the power plant 3 and the tidal flow of the loads 41 and 42 of the substation 4. Are sampled and stored in the online database 11.

  Next, the data of the online database 11 of the system monitoring device 1 and the parameter database 12 of various constants are periodically transmitted to the stabilization device 2 via the transmission lines 111 and 121.

  Next, the latest system configuration is estimated by the system estimation means 21 based on the data received by the stabilization device 2.

  Next, on the basis of the estimated system configuration, the fact that the generator dropout has occurred with respect to the current power generation amount in the generator unit connected to the system by the load control amount determination means 22 for each generator. Assuming that the load control amount is calculated in the case where the generator is dropped.

  Next, based on the calculated load control amount, the load control target determining unit 23 selects the load with the most stable system frequency using the load cutoff priority of the parameter data.

  This series of operations is performed every time the online data is rewritten, and the pre-computation results with the latest data are always stored.

  Here, it is assumed that a certain generator 31 or 32 has dropped out at the power plant 3. The power plant 3 transmits a drop command to the stabilization device 2 via the drop command line 33. The stabilization device 2 that has received the dropout command uses the load control calculation result of the dropout generator, and transmits a cut-off command to the corresponding load 41 and / or 42 in the substation 4 via the load cut-off command line 43. And shut off the load.

  Here, a calculation example in the load control amount determining means 22 for each generator will be described with reference to FIGS.

  FIG. 2 is an example graph for calculating a load control amount assuming that a generator with a generator power generation amount of 70 MW has dropped. A system constant is calculated from the system configuration estimated by the system estimation means 21 and can be calculated using equations (1) and (2).

ΔP = KΔf …………………………………………………… (1)
Here, ΔP is a supply and demand imbalance rate (% MW), K is a system constant, and Δf is a transition frequency fluctuation lowest point (% Hz).

PG-PL = (1 / fn) · M · df / dt (2)
Here, PG is a power generation amount of the entire system, PL is a load amount of the entire system, fn is a rated frequency, and M is a unit inertia constant (MW · s / MVA) of the generator.

  Equation (1) is calculated from the relationship between the supply and demand imbalance amount and the lowest point frequency, and in Equation (2), the relationship between the frequency change rate is calculated using the equation of motion of each generator, The load control amount straight line 6 of the machine can be calculated. Using the calculated load control amount straight line 6, it is possible to obtain a load control amount point corresponding to the allowable frequency fluctuation. When the allowable frequency fluctuation is −1.0 Hz, the load control amount point is an intersection 61 between −1.0 HZ and the load control amount straight line 6, and it can be seen that the load control amount at this time is 35 MW.

  Next, the load control target determination unit 23 exceeds the load control amount calculated from the load control amount determination unit 22 for each generator = 35 MW, and exceeds the required load control amount based on the load priority of the parameter database. The control target whose amount is the minimum value is determined.

  FIG. 3 is an expected frequency fluctuation locus diagram obtained when load control is performed based on the calculation result calculated from FIG. 2. From the assumed frequency fluctuation locus 62 in this case, the frequency fluctuation when the load control obtained by the load control amount determining means 22 for each generator is performed can be stabilized at -1.0 Hz, that is, 59.0 Hz at the bottom. I understand.

  Next, the load correction control for correcting the load control based on the above-described online data based on the pre-computation based on the power generation amount of the actually shut off generator will be described based on the present invention.

  Returning to FIG. 1, the stabilization device 2 includes a difference determination unit 24, a correction load control amount determination unit 25, and a correction load control target determination unit 26 for load correction control. The difference determination unit 24 determines the difference between the calculation power generation amount adopted in the preliminary calculation and the power generation amount immediately before the generator that has actually dropped out. The corrected load control amount determining means 25 calculates a correction load control amount that is commensurate with the difference in power generation amount. The corrected load control target determining unit 26 selects a target load from the corrected load control amount using the load cutoff priority order of the parameter data. The generator power generation amount 34 is stored in the online database 11 of the system monitoring apparatus 1 as online data. The power generation amount transmission line 35 transmits the generator power generation amount immediately before dropping off. Due to the difference in the power generation amount of the dropout generator, an additional cut-off load, for example, the load 41 is cut off as an additional portion.

  Next, the operation of the difference determination unit 24 will be described including FIG. 2 and FIG. A case will be described in which the expression (3) is established for the generator power generation amount 34 stored on-line data and the generator power generation amount just before dropping off transmitted by the power generation amount transmission line 35.

PG1 <PG2 ……………………………………………… (3)
Here, PG1 corresponds to the power generation amount of the online storage data adopted for the pre-calculation, and PG2 corresponds to the power generation amount immediately before dropping.

  In this case, since the power generation amount PG2 just before the dropout exceeds the power generation amount PG1 adopted in the precalculation, the dropout amount is larger than the result calculated in the precalculation, and the actual required load control amount is larger than the precalculation result. Naturally grows. For this reason, the load control amount is insufficient, and the assumed frequency fluctuation 62 obtained by the prior calculation in FIG. 3 cannot be realized, and the locus of the insufficient control frequency fluctuation 73 is traced. Therefore, the permissible frequency fluctuation of −1.0 Hz, which is the permissible frequency fluctuation point 75, cannot be ensured.

  Therefore, the difference determination unit 24 determines the difference in power generation amount. The difference determination means can obtain the difference by the equation (4).

PG3 = PG2-PG1 ……………………………… (4)
Here, PG3 is a differential power generation amount between the power generation amount employed in the pre-calculation and the power generation amount immediately before dropping.

  Next, the operation of the corrected load control amount determining means 25 for obtaining the original load control amount based on the differential power generation amount PG3 will be described. The load control amount to be corrected with respect to the load control amount 61 of FIG. 2 obtained by the pre-calculation can be obtained by Expression (5).

ここで、ΔＰＦは事前演算時の総脱落発電量ＰＧから事前演算の負荷制御量ＰＧ１で求められた直線６の傾きに対し、差分発電量ＰＧ３分を補正した傾きとなり、傾きΔＰＦから不足制御補正負荷制御量直線７を求めることができる。求められた不足制御補正負荷制御量直線７から、許容周波数変動−１．０Ｈｚとした場合の不足制御負荷制御量点７１は−１．０ＨＺと不足制御負荷制御量直線７との交点となり、この時の負荷制御量は４５ＭＷとなる。図２から求まる不足制御補正負荷制御量点７１と事前演算負荷制御量点６１の差分が、追加負荷制御量７２となり、１０ＭＷの負荷補正値を算出する。算出された負荷補正値を追加制御することにより、想定周波数変動６２と不足制御周波数変動７３の差分である不足制御周波数変動差分７４を補正することで、想定周波数６２の軌跡を実現することが可能となる。

Here, ΔPF is a slope obtained by correcting the difference power generation amount PG3 with respect to the slope of the straight line 6 obtained from the total dropout power generation amount PG at the time of pre-calculation by the load control amount PG1, and the shortage control correction is performed from the slope ΔPF. A load control amount straight line 7 can be obtained. From the obtained shortage control correction load control amount straight line 7, the shortage control load control amount point 71 when the allowable frequency fluctuation is −1.0 Hz is an intersection of −1.0 HZ and the shortage control load control amount straight line 7. The load control amount at that time is 45 MW. The difference between the shortage control correction load control amount point 71 obtained from FIG. 2 and the pre-computed load control amount point 61 becomes the additional load control amount 72, and a 10 MW load correction value is calculated. By additionally controlling the calculated load correction value, the locus of the assumed frequency 62 can be realized by correcting the insufficient control frequency variation difference 74, which is the difference between the assumed frequency variation 62 and the insufficient control frequency variation 73. It becomes.

  A case where the formula (6) is established as an opposite case will be described.

PG1> PG2 ……………………………………………… (6)
In this case, since the power generation amount PG2 just before the drop-off is lower than the power generation amount PG1 adopted in the pre-calculation, the drop-off amount is smaller than the result calculated by the pre-calculation, and the actual required load control amount is less than the pre-calculation result Naturally it will be less. For this reason, since there is too much load control amount, the assumed frequency fluctuation | variation 62 calculated | required by the prior | preceding calculation of FIG. 60 Hz), causing disturbance of the system frequency.

  Therefore, by performing the same processing as in equation (3), overcontrol load control when the allowable frequency is set to -1.0 Hz from the overcontrol correction load control amount 711 obtained from equations (4) and (5). The quantity point 712 is an intersection of −1.0 Hz and the over-control load control amount straight line 711, and the load control amount at this time is 25 MW. The difference between the load control amount point 712 obtained from FIG. 2 and the pre-computed load control amount point 61 becomes the reduction control amount 713, and a load correction value of −10 MW is calculated. By performing reduction control on the calculated load correction value, the trajectory of the assumed frequency 62 can be realized by correcting the overcontrol frequency fluctuation difference 715 that is the difference between the assumed frequency fluctuation 62 and the overcontrol frequency fluctuation 714. Become. As shown in FIG. 2, as a method for obtaining the relationship of the frequency fluctuation with the load control amount, the correlation of the frequency fluctuation amount with the fluctuation of the power flowing through the line is obtained, and this is used to obtain the load correction control amount. Can be sought.

  Next, the operation of the correction load control target determination unit 26 will be described. Necessary load corresponding to the additional load control amount 72 or the reduced load control amount 713 of FIG. 2 calculated again based on the load cutoff priority order of the remaining parameter data, excluding the control target load determined by the prior calculation. The control target that is the minimum value exceeding the control amount is determined. The determined correction load object and the control load object determined in the pre-computation are combined, and a load shedding command is transmitted to the substation 4 via the line 42, and the load 42 and the additional interrupting load determined in the pre-computation are transmitted. 41 or the reduced load 421 reduced from the load 42 of the pre-calculation selection result is cut off.

  Next, frequency correction control after correction control will be described.

  This is a method for measuring the frequency trajectory after the control with respect to the load control performed by the pre-computation and the correction control, comparing the result with the pre-computation result, and performing the correction control again.

  FIG. 4 is an overall configuration diagram of a power system frequency stabilizing device according to a second embodiment of the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and redundant description will be avoided, and only different parts will be described.

  The stabilizing device 2 includes a frequency difference determination unit 27, a correction load control amount determination unit 28, and a correction load control target determination unit 29 for the second load correction control. The difference determination means 27 determines the difference by comparing the plurality of predicted frequencies predicted by the prior calculation with the system frequency after the dropout. The correction load control amount determination means 28 calculates a correction load control amount corresponding to the frequency difference. The corrected load control target determining unit 29 selects a target load from the corrected load control amount using the load cutoff priority order of the parameter data. The frequency transmission line 52 transmits the frequency of the system 5 immediately after dropping.

  FIG. 5 is a frequency fluctuation locus diagram for explaining an example of the concept of post-correction control. As shown in the figure, post-correction control trajectories 81 to 83 that take into account the influence of load drop and the like are calculated by pre-calculation with respect to the ideal control trajectory 8 obtained by pre-calculation, and which post-correction control the actual frequency trajectory is. It is determined whether or not the trajectories 81 to 83 are approximate. For example, when approximate to the posterior correction control locus 83, the ideal control locus 8 can be realized by additionally blocking the posterior correction control amount calculated by the posterior correction control locus 83, which is calculated by the pre-calculation. .

  Next, a further additional correction method using the rate of change of the system frequency after performing the above correction control and the inertia constant of the generator remaining in the subsequent system will be described with Expression (7).

ΔPm = Mdf / dt ………………………… (7)
Here, ΔPm is a post-correction load control amount, and M is a capacity weighted average of the unit inertia constant of the generator left in the system.

  It is possible to estimate the supply and demand imbalance by performing control based on the pre-computation result and the correction control and calculating the subsequent posterior frequency change rate 9 (FIG. 5) from the equation (7). Therefore, the ideal control trajectory 8 can be realized by additionally executing the post-correction control corresponding to the post-calculated supply and demand imbalance amount.

  According to the embodiment of the present invention described above, it is possible to flexibly adapt to the state change of the generator power generation amount due to the time difference of the online data by directly capturing the data immediately before the generator that has actually dropped. Moreover, it becomes easy to maintain the allowable frequency fluctuation.

  DESCRIPTION OF SYMBOLS 1 ... System | strain monitoring apparatus, 11 ... Online database, 12 ... Parameter database, 2 ... Stabilizer, 21 ... System | strain estimation means, 22 ... Load control amount determination means, 23 ... Load control object determination means, 24 ... Difference determination means, 25 ... Correction load control amount determination means, 26 ... Correction load control object determination means, 27 ... Frequency difference determination means, 28 ... Correction load control amount determination means, 29 ... Correction load control object determination means, 3 ... Power plant, 31, 32 ... Generator drop-off command line, 34 ... Generator power generation amount online data, 35 ... Generator power generation amount line just before drop-off, 4 ... Substation, 41, 42 ... Load, 421 ... Reduced cut-off load, 43 ... load cutoff command line, 5 ... power system, 51 ... data input line, 6 ... pre-computed load control amount straight line, 61 ... pre-computed load control amount point, 62 ... assumed frequency fluctuation locus, ... Insufficient control correction load control amount straight line, 71 ... Insufficient control correction load control amount point, 72 ... Additional load control amount, 73 ... Insufficient control frequency fluctuation locus, 74 ... Insufficient control frequency fluctuation difference, 75 ... Allowable frequency fluctuation point, 711 ... overcontrol correction negative control amount straight line, 712 ... overcontrol correction load control amount point, 713 ... reduced load control amount, 714 ... overcontrol frequency fluctuation locus, 715 ... overcontrol frequency fluctuation difference, 716 ... reference frequency point, 8 ... Pre-calculation frequency trajectory, 81 .. Post-correction control trajectory by pre-calculation, 82 .. Post-correction control trajectory by pre-calculation, 83 .. Post-correction control trajectory by pre-calculation, 9.

Claims (6)

  A load that estimates the state of the current system based on system information obtained in advance as sampling data and calculates in advance the load control amount to be executed when the generator is disconnected for each generator connected to the system In the power system frequency stabilizing device provided with the control amount pre-calculation means, the power generation amount comparison means for comparing the power generation amount of each generator adopted for the prior calculation of the load control amount with the power generation amount immediately before the accident, and the power generation Load correction control amount calculation means for calculating an excess or deficiency load correction control amount with respect to the load control amount calculated in advance based on the output of the amount comparison means, the load control amount calculated in advance and the load A power system frequency stabilization device comprising load control means for performing load control according to a correction control amount.   In Claim 1, when the power generation amount immediately before the accident of the drop-off generator is smaller than the power generation amount adopted in the advance calculation, the load control means executes load control reduced according to the small amount. A characteristic power system frequency stabilizer.   In Claim 1, when the power generation amount immediately before the accident of the drop-off generator is larger than the power generation amount adopted in the advance calculation, the load control means executes load control increased according to the amount of power generation. A characteristic power system frequency stabilizer.   4. The frequency reduction prediction means for predicting a plurality of stages of the frequency reduction amount of the power system due to the occurrence of a generator dropout accident, the frequency reduction results of the power system immediately after the actual accident, and the plurality of frequency reductions Frequency reduction comparison means for comparing with an expected value, and second load correction control amount calculation for calculating a second load correction control amount for excess and deficiency with respect to a load control amount calculated in advance based on the comparison result And a load control means for executing load control in accordance with the load control amount calculated in advance, the load correction control amount, and the second load correction control amount. Frequency stabilizer.   5. The means for determining the correlation of the frequency fluctuation amount with the fluctuation of the power flowing through the line according to claim 1, and calculating the load correction control amount for suppressing the frequency fluctuation within an allowable range based on the correlation. A power system frequency stabilizing device comprising: means.   Electricity that estimates the state of the current grid based on grid information obtained in advance as sampling data, and calculates in advance the load control amount to be executed when the generator is disconnected for each generator connected to the grid In the system frequency stabilization control method, the power generation amount of each generator adopted in the calculation of the load control amount in advance is compared with the power generation amount comparison step for comparing with the power generation amount immediately before the accident, and the comparison result in this power generation amount comparison step. Based on the load correction control amount calculation step for calculating an excess / deficiency load correction control amount with respect to the load control amount calculated in advance, and the load control amount and the load correction control amount calculated in advance A power system frequency stabilization control method comprising a load control step for executing load control.

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