JP4094206B2 - Power system stabilizer - Google Patents

Description

一方、分離系統内の電制量が事前潮流を超える場合は、Ｂ１ｎは数１０により算出される。
【００５４】
【数１０】
Ｂ１ｎ＝ａ×（事前潮流量―分離系統内電制量）／（事前潮流量）
指標Ｂ１ｎ以外にも周波数安定度のために考慮できる指標として、想定分離系統内瞬動予備力優先指標、想定分離系統内発電機タイプ優先指標、想定分離系統内電制機出力分散指標があり、本実施例では分離系統内瞬動予備力優先指標Ｂ２ｎを用いている。
【００５５】
たとえば、発電機の瞬動予備力は周波数変動に対する調整力を意味する。Ｂ２ｎは分離系統における瞬動予備力合計がある規定値以上残るように、電制発電機を選択することを目的とした指標で、数１１で計算する。
【００５６】
【数１１】
Ｂ２ｎ＝ｉ×Ｇｎ（絶対条件時） （ｏｒ）
Ｂ２ｎ’＝１＋ｉ×Ｇｎ（優先条件時）
ただし、ＧＦ（SUB(S)−SHD(N−1)−Ｇｋ）＞CONSTの場合、Ｇｎ＝１
また、ＧＦ（SUB(S)−SHD(N−1)−Ｇｋ）＜CONSTの場合、Ｇｎ＝０
ここで、ｉ：分離系統内瞬動予備力優先パラメータ、CONST：定数（設定パラメータ）、Ｇｋ：Ｎ回目選択ステップで電制候補になった発電機、SHD(N−1)：(N−1)回目選択ステップまでに選択済みの電制発電機集合、SUB(S)：想定分離系統Ｓ内の発電機集合、ＧＦ(X)：発電機集合Ｘが保持するガバナフリー量（％）である。
【００５７】
電圧安定度効果指標Ｃｎのなかで、最も電圧安定度に影響を与える指標として、無効電力余裕量優先指標Ｃ１ｎがある。発電機の無効電力余裕量は電圧降下を防止して電圧を維持できる調整量を意味し、指標Ｃ１ｎはこの調整量を系統内に残しておくことを目的とする。対象系統内の無効電力余裕量の合計値がある規定値以上となるように指標Ｃ１ｎを以下のように求める。
【００５８】
発電機の無効電力余裕量は、発電機可能出力曲線（ＭＥＬカーブ）を使用し、発電機可能出力曲線（ＭＥＬカーブ）と故障発生前の有効出力から最大無効出力を求め、求めた最大無効出力から故障発生前の無効電力を差し引き、無効電力余裕量とする。この条件は、以下により定式化する。
【００５９】
Ｇｋ：Ｎ回目選択ステップで電制候補になった発電機、SHD(N−1)：(N−1)回目選択ステップまでに選択済みの電制発電機集合、SUB(S)：対象系統S内の発電機集合、ＲＱ(X)：発電機集合Ｘが保持する無効電力余裕量（%）、ｑ：対象系統内無効電力余裕量優先パラメータ、CONST：定数（設定値）として、数１２より求める。
【００６０】
【数１２】
Ｃｎ＝ｑ×Ｇｎ（絶対条件時） （ｏｒ）
Ｃｎ’＝１＋ｑ×Ｇｎ（優先条件時）
ただし、ＲＱ（SUB(S)−SHD(N−1)−Ｇｋ）＞CONSTの場合、Ｇｎ＝１
また、ＲＱ(SUB(S)−SHD(N−1)−Ｇｋ）＜CONSTの場合、Ｇｎ＝０
図５に、電制効果指標値及び電制発電機候補の管理テーブルを示す。図示例は、対象系統にある発電機Ｇ１〜Ｇｎから、電制候補発電機を選択する過程を示している。本実施例では、過渡安定度効果指標ＡｎにＡ１ｎ，Ａ２ｎ，Ａ３ｎ、周波数安定度効果指標ＢｎにＢ１ｎ，Ｂ２ｎ、電圧安定度効果指標ＣｎにＣ１ｎを用い、電制効果指標Ｔｎはこれら各指標の積として算出される。図示のように、発電機Ｇ１はＡ１ｎ＝０、Ｔ１＝０で、既に、電制候補となっている。今回の演算では、発電機Ｇ２の電制効果指標Ｔ２が１２０と最も高く、電制候補に選択される。
【００６１】
図６に、本実施例と従来例の系統安定化制御の比較例を示す。（ａ）は対象となる系統モデル（事故シーケンス）で、Ｐ点で系統事故（地絡）が発生した場合を検討する。（ｂ）は制御結果の比較表を示す。
【００６２】
従来の系統安定化制御では、事故発生時、まず、過渡安定度演算制御、次いで周波数安定度演算制御が個別に行われる。Ｐ点の事故で、過渡安定度維持に必要な電制量が３００MWと算出されたとすると、Ｆ発電所の発電機Ｇ１（４００MW）が最適な電制用発電機に選択される。
【００６３】
次に、進展故障により、Ｐ点で系統が分断すると、点線で示す分離系統内では需給不均衡量が＋３００MW（発電量超過分）となるので、更に３００MWの電制が必要になる。しかし、Ｇ１は電制済みのため、次に電制量の小さいＦ発電所のＧ２（７００MW）が電制される。この結果、分離系統内では、需給不均衡量が−４００MWとなって供給不足を生じるため、次の周波数安定度維持制御で、Ｂ変電所の負荷制限（４００MW）が実施される。結局、従来の制御方式では、過渡安定度維持制御によるＦ発電所Ｇ１及び周波数安定度維持制御によるＦ発電所Ｇ２の電制が２回行われ、制御量の合計が１１００MW、また、周波数安定度維持制御によるＢ変電所の負制が１回行われ、制御量４００MWとなる。
【００６４】
これに対し、本実施例の系統安定化制御では、最初のＰ点における事故発生時の統合型電効果指標の演算から、最適な電制候補としてＦ発電所のＧ２（７００MW）が選択される。これは、Ｐ点における事故前の事前潮流量が７００MWであり、過渡安定度としては３００MWで安定化できることから、Ｆ発電所Ｇ２に対する想定分離系統内需給バランス指標Ｂｎの値が大きくなり、統合電制効果指標ＴｎとしてはＧ２の値が最も大きくなるためである。この結果、進展故障により、Ｐ点で系統が分断しても、分離系統の需給バランスが保たれているため、系統内の各発電機に脱調を生じるものがなく、本例この後の電制や負制が必要なくなる。この結果、従来方式に比べて、制御量、制御回数を大幅に低減できる。
【００６５】
【発明の効果】
本発明の電力系統安定化制御装置によれば、系統の周波数安定度、さらには電圧安定度と協調性のある過渡安定度維持の制御が可能となり、系統安定化のための制御量や制御回数を大幅に低減できる。また、系統の安定化にとって多観点から最適な制御対象を選択できるので、システムの信頼性を向上できる。
【図面の簡単な説明】
【図１】本発明の一実施例による電力系統安定化装置の構成図。
【図２】本発明の系統安定化制御の概要を示す説明図。
【図３】本発明による系統安定化制御の処理手順の一例を示すフローチャート。
【図４】想定分離系統内需給バランス指標の算出方法を示す系統図。
【図５】電制効果指標値及び電制発電機候補の管理テーブルのデータ構成図。
【図６】系統安定化制御の本実施例と従来例を比較する説明図。
【符号の説明】
１０…中央演算装置、２０…伝送路、３０…情報収集端末、４０…制御端末、１０１…系統安定化制御演算部、１０２…統合型電制効果指標演算部。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power system stabilizing device.
[0002]
[Prior art]
When a grid fault occurs in the power system, before the multiple generators in the grid are shaken or stepped out in order to prevent the system from causing an imbalance in the power supply and demand due to the accident, System stabilization control is performed to disconnect the generator and the like from the system. System stabilization control performs transient stability calculation immediately after an accident, selects a generator that needs to be disconnected to maintain transient stability, and performs power limitation (electric control). In addition, frequency stability calculation and voltage stability calculation are performed along with the generation of the separated system, and electric control and load limitation (negative control) are performed to keep the frequency and voltage of the system constant. Conventionally, each of the above stability maintenance controls is performed individually. As examples of individual system stabilization control, JP-A 61-46123 and JP-A 10-42740 are related to transient stability maintenance control, and JP-A 6-113464 and JP-A 9-46908 are related to system frequency maintenance control. and so on.
[0003]
In addition, the system stabilization control method includes a pre-calculation method and a post-calculation method. The former predicts and calculates a transient state change spillover transition in accordance with the power system dynamic characteristics model for the accident assumed in advance, and selects a generator that can be stabilized by electric control from this prediction result. Sometimes, the generator for electric control is determined from among the generators selected in advance. The latter should capture accident information, etc. after the accident occurs, predict whether the generator will shake or step out due to the influence of the accident, and control when it is determined that control is necessary from the result of the calculation. A generator is selected, and the selected generator is disconnected from the system before the system is shaken or stepped out (JP-A-6-269123 and JP-A-8-182199).
[0004]
[Problems to be solved by the invention]
It is desirable that the system stabilization control has a small control amount (electric control amount / negative control amount) with respect to the system and can quickly suppress the fluctuation of the system. Being able to stabilize more quickly with a small amount of control leads to improved system reliability and total energy efficiency from power generation to supply.
[0005]
However, in the conventional system stabilization control, since the three system stability maintenance controls are performed individually, there is a lack of cooperation between the controls, making it difficult to stabilize in later control, There is a problem that increases. For example, after the transient stability maintenance control, there may be no generator with the optimal amount of control for maintaining the frequency stability. For this reason, it is necessary to carry out electric control that is more than the required electric control amount, and negative control is necessary from the balance of supply and demand. For example, the control amount (electric control amount / negative control amount) increases and system operation increases. Not only will efficiency decrease, it will take time to stabilize the grid.
[0006]
The object of the present invention is to take into account the problems of the prior art described above, considering the coordination of a plurality of stability maintenance controls, the system after an accident is quickly stabilized with a minimum control amount, and a highly reliable power system stability It is in providing a conversion apparatus. According to the present invention, the system operation efficiency can be improved.
[0007]
[Means for Solving the Problems]
The present invention that achieves the above object is designed so that the frequency stability and the voltage stability are considered simultaneously when the control of the transient stability maintenance is performed due to the occurrence of a system fault so that the three system stability can be coordinated. This was achieved by creating a control algorithm for selecting a damp generator.
[0008]
The present invention inputs system operation information including accident information, and is a generator suitable for power supply restriction (hereinafter referred to as electric control) necessary for stabilization from the transient stability of the system obtained based on the information at the time of the system accident. In the power system stabilization device that selects the generator from the system and outputs a shutoff command for the selected generator, the transient stability of the system is selected in order to select the generator (hereinafter referred to as the “electric generator”) necessary for the power source limitation. Index effective in maintaining the degree of stability (hereinafter referred to as transient stability effect index) and index effective in maintaining the frequency stability (hereinafter referred to as frequency stability effect index), or the transient stability effect index, the frequency stability effect Each index value of the index and the index effective for maintaining the voltage stability (hereinafter referred to as the voltage stability effect index) is calculated for each generator in the system, and the control effect index integrated based on each calculated index value Value is calculated and the electric control effect index value is Is provided with a electrically controlled candidate selecting means for selecting a high power motor as the electrically controlled candidate.
[0009]
When it is determined that the power generation candidate generator is disconnected from the grid and the system can be stabilized, the power control candidate is selected as the power generation generator. On the other hand, when it is determined that the stabilization of the system is impossible, the selection of the electric control candidate by the electric control candidate selection means is repeated in order to select an additional electric generator.
[0010]
The electric control effect index value is obtained by a product of the transient stability effect index and a frequency stability effect index, or a product of these and the voltage stability effect index.
[0011]
The transient stability effect index is a product of a selected absolute condition index that excludes those selected as the control generator or the control candidate and a generator acceleration index that makes it easier to select a generator with a higher tendency to step out. The frequency stability effect index includes, in the assumed separation system created from the accident point, the total output of the electric generator does not exceed the tidal flow that was flowing to the accident point before the accident, and the tidal current It includes a supply and demand balance index that makes it easier to select a generator with an output close to the quantity.
[0012]
Further, the power control candidate selecting means determines that the power control effect index value is not more than a specified value (predetermined value not less than zero) for all the generators in the system, and the system cannot be stabilized. For each generator in the system using an arithmetic expression relaxed so that the frequency stability effect index, or each index value of the frequency stability effect index and the voltage stability effect index does not become the specified value or less. Each index value is calculated, and an integrated control effect index value is calculated based on each calculated index value, and the generator with the highest control effect index value according to the relaxed calculation formula is selected as a control candidate. .
[0013]
The operation of the present invention will be described. FIG. 2 shows an outline of selection of the electric generator according to the present invention. When a system fault is detected, the system transient stability is calculated based on system operation information including accident information (accident point, accident type, etc.). In other words, it is necessary to stabilize the system when it is determined that the generator will be shaken or stepped out due to the accident (transient stability calculation) and it is determined that the generator will be unstable (swing or stepped out). Select a candidate for an electrical generator and perform the transient stability calculation again. As a result, if stabilization can be achieved, the candidate for electric control is selected as an electric generator for electric control, and a cutoff command is output.
[0014]
In the present invention, when selecting an electric control candidate, an electric control effect index taking into account the maintenance of the transient stability, the maintenance of the frequency stability, and also the maintenance of the voltage stability, that is, the integrated electric control effect index according to Equation 1 is systematized. The generator having the highest integrated index is selected as a candidate for electric control.
[0015]
[Expression 1]
Tn = An · Bn · Cn (or)
Tn = An · Bn
Here, An is a transient stability effect index function, Bn is a frequency stability effect index function, and Cn is a voltage stability effect index function.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a power system stabilizing device according to the present invention will be described with reference to the drawings. FIG. 1 shows a schematic system configuration of the power system stabilizing device. This system includes a central processing unit 10, a transmission path 20, a plurality of information collection terminals 30, and a plurality of control terminals 40. The central processing unit 10 is connected to each information collection terminal 30 via the transmission line 20 and is connected to each control terminal 40 via the transmission line 20.
[0017]
The information collection terminals 30 are distributed in the power system, and TM (telemeter) data, which is system operation information of the power system, for example, the generator terminal voltage, active / reactive power, transmission line active / reactive power , Load bus voltage, consumption active / reactive power and other data, and input SV (supervisor) data, for example, data on device configuration changes such as relay operation, circuit breaker switching status and status changes. Then, the inputted system operation information is transmitted to the central processing unit 10 through the transmission path 20. Each information collecting terminal 30 can also input a transformer (PT), a current transformer (CT), or a contact input (such as a protection relay operation) that is analog information when an accident occurs.
[0018]
Based on the information from each information collection terminal 30, the system stabilization control calculation unit 101 of the central processing unit 10 uses a combination of pre-calculation and post-calculation, and when a power system accident occurs, a plurality of control objects, for example, A calculation for sequentially selecting a plurality of generators distributed in the system is performed, and a control command according to the integration result is output to the control terminal 40 via the transmission line 20.
[0019]
Prior calculation by the system stabilization control calculation unit 101 is based on the system operation information from the information collecting terminal 30, and for the accident case assumed in advance, transient stability calculation according to the power system dynamic characteristic model, stability determination ( Step-out judgment), stabilization countermeasure calculation (electric control candidate selection calculation) is performed, and the generators to be controlled for stabilization measures are registered in advance in association with the assumed accident case according to each calculation result. deep.
[0020]
When a grid fault occurs and stabilization control is required, a transient stability calculation is performed using a pre-registered generator as a power control candidate. If stabilization is possible, a shutoff command for the generator is issued to the control terminal 40. Output to. If stabilization is impossible, the control candidate is reselected and the above process is repeated. Immediately after the accident, the generator registered in advance calculation is shut off, and if the control amount is still insufficient, the control calculation for selecting and disconnecting another electric generator may be performed. .
[0021]
The central processing unit 10 of the present embodiment includes an integrated electric control index calculation unit 102 together with the system stabilization control calculation unit 101 described above. As a result of the stability calculation after the accident, it is determined that the system cannot be stabilized. In this case, a stabilization measure calculation is performed for calculating the electric control effect index Tn for each generator and adding the generator having the highest Tn to the electric control candidates. The integrated power control index calculation unit 102 is mainly composed of a power control effect index calculation algorithm which will be described later, and can be stored in a storage medium and easily added to a conventional system stabilizing device for maintaining transient stability. Note that the system stabilization control calculation unit 101 and the integrated electric control index calculation unit 102 may be integrally configured.
[0022]
In this embodiment, the system stabilization control method uses both pre-accident calculation and post-accident calculation. However, the method of the present invention is also applicable to a control method that does not perform the pre-accident calculation, and calculates a power control effect index Tn for each generator and selects a power control candidate. Moreover, it is applicable also to the determination of the control system by calculation before an accident.
[0023]
The control terminal 40 is arranged in units of control equipment or electrical facilities with control equipment. As control commands calculated in the central processing unit 10, control commands based on pre-calculation and control commands based on post-calculation are transmitted through the transmission line 20. Input. Then, in the control terminal 40 to which the control command is input from the arithmetic device 10, as a system stabilization control, an electric control for disconnecting a specified generator from the system or a negative control for disconnecting a specific load from the system is performed. At the same time, on / off control of power capacitors (SC) and shunt reactors (ShR) installed in substations and the like is performed simultaneously. When control is performed so that the generator is disconnected from the system by the control terminal 40, the system is stabilized.
[0024]
FIG. 3 shows an example of the processing flow of the power system stabilization arithmetic device. First, system operation information (TM data, SV data) is sequentially input from the information collection terminal 30, and a system model necessary for transient stability calculation is created based on the input system operation information (S10-1). Next, assuming the accident sequence (separated system model) for the accident point assumed in advance, transient stability calculation (S10-2), step-out determination (S10-3), stabilization countermeasure calculation (S10-4) ) Is performed.
[0025]
The accident sequence here includes the accident point where the accident occurred, the accident impedance at the point of the accident, the aspect where the accident occurred, the circuit breaker reclosing method, the success / failure of the circuit breaker reopening, the presence or absence of the line opening, and each The occurrence timing of events is considered. The specific accident sequence is, for example, a setting that interrupts three cycles (assuming an ultra-high voltage system and assuming the operation of a protection relay), or a setting where the location where the accident occurred is the load side closest end of the line Is possible.
[0026]
In the transient stability calculation in step S10-2, a dynamic characteristic simulation of the power system is performed. As an example, the Y method algorithm will be described. The interface calculation is performed by Equation 2, which combines a differential equation expressing the internal state of the control system and a simultaneous equation of a circuit network connecting each generator.
[0027]
[Expression 2]
dx / dt = Ax + Bu
YE = I
u = g (y, E)
I = h (y, E)
Where x: state vector, u: input signal, A, B: constant, I: node injection current, E: node voltage, Y: node admittance matrix. By solving the above equation, for example, the phase angle is obtained as the state of the generator, and the phase angle difference between this phase angle and the reference generator can be obtained.
[0028]
In step-out determination in step S10-3, the transient stability calculation result (here, phase angle difference) is used, and step-out determination of the generator connected to the system is performed. If there is a generator to be stepped out, the stability calculation result becomes unstable, and the control target is selected. As an example of the step-out determination method, a stability determination method based on the internal phase angle difference of each generator with respect to the reference generator will be described based on waveform data based on the transient stability calculation result.
[0029]
In transient stability calculation, a transient state is calculated for each time using a differential equation indicating dynamic characteristics, and an internal phase angle of each generator is obtained. Here, by determining the internal phase angle difference between the reference generator and each generator, it is possible to determine how the respective generators are stably affected by the accident. In other words, when the phase angle difference with respect to the reference generator increases and tends to diverge, the generator tends to step out, and unless the stabilization measures are taken, the generator cannot be operated synchronously, causing a large-scale power outage. It will be.
[0030]
In this embodiment, a certain threshold value for the phase angle difference of the generator is used to determine whether or not the generator is out of step. In addition, it recognizes the waveform based on the phase angle difference of each time step, finds the amplitude from the maximum value and minimum value of the waveform data, and determines whether each amplitude is divergent (unstable) or convergent (stable). It can also be determined. Further, the step-out determination can be performed using the angular velocity or acceleration energy of each generator instead of the phase angle difference of each generator.
[0031]
When it is determined in S10-3 that the step-out determination result is unstable, an operation for selecting a control target necessary for system stabilization is performed (S10-4). Control targets necessary for system stabilization include loads such as generators and consumers, or power capacitors (SC) and shunt reactors (ShR) installed in substations. The case of selecting is described.
[0032]
In the selection of the power generator for power control in S10-4, first, a power control effect index Tn for each generator is calculated as described later, and the generator having the highest index is set as a power control candidate. Next, for each generator in the sequence in which the candidate for electric control is disconnected from the system, if the above-mentioned transient stability calculation is performed and the result is stable, that is, each generator in the system after the accident is out of step. If it does not occur, the previous electric control candidate is set as the electric generator for electric control.
[0033]
When the result of the step-out determination is determined to be stable in S10-3, the calculation result is registered (S10-5). For each assumed accident case, the electric power generator determined in S10-4 is associated with each other and registered in the table.
[0034]
Next, it is determined whether an accident has occurred in the power system based on information from the information collection terminal 30 (S20). Here, based on analog information (PT, CT, etc.) and contact input (relay operation, etc.) from each information collection terminal 30, the presence / absence of an accident, the appearance of an accident (accident case), etc. are determined. In step S20, it is also possible to calculate the accident point location calculation and obtain the accident point without using the accident point location device.
[0035]
If it is determined in step S20 that an accident has occurred, the control generator shut-off command registered in step S10-5 is output, and the process proceeds to post-calculation from step S30. When no accident has occurred, the process returns to step S1O-1, and the processes of steps S10 and S20 are repeated according to the newly input data.
[0036]
In the calculation after the accident, the transient stability calculation is performed by reflecting the result of the pre-calculation, the information on the accident point and the aspect of the accident (S30). In this stability calculation, the phase angle difference is obtained in the same manner as described above, and it is determined whether it is stable or unstable, that is, whether or not a step-out occurs (S40). When the pre-registered generator is shut off immediately, the transient stability calculation is performed in the sequence after the shut-off. Further, when there is no identical accident case registered in advance, a transient stability calculation is performed based on system operation information after the accident.
[0037]
If the determination of the stability calculation result is not “stable”, the electric control effect index Tn is calculated by Equation 1 for all the generators (1 to n) in the system (S50). Then, it is determined whether there is a generator whose Tn is larger than the specified value (S60). If there is a generator, the generator Gn having the maximum Tn is selected as a candidate for power control (S70), and the process returns to step S30. Note that generators that have already been controlled or generators that have been raised as candidates for control are not selected again because they include an operation index with Tn = specified value, as will be described later. . The specified value is a predetermined value equal to or greater than 0, and usually a value greater than 0 is set.
[0038]
In step S60, when the power control effect index of all the generators reaches the specified value, the power control effect index calculation formula is switched (S100), and the condition is relaxed as described below. The functions of the indices Bn and Cn are defined as functions that can be 0, as shown in Equation 3. On the other hand, a function of Formula 4 is prepared so that the index does not become zero.
[0039]
[Equation 3]
Bn = αB (αB ≧ 0)
Cn = αC (αC ≧ 0)
[0040]
[Expression 4]
Bn ′ = 1 + Bn
Cn ′ = 1 + Cn
When this type 4 function is used, the electrical control effect index Tn in formula 1 is switched to Tn ′ in formula 5.
[0041]
[Equation 5]
Tn '= An / Bn' / Cn '
After switching the calculation formula of the electric control effect index in step S100, the electric control effect index T1 ′ to Tn ′ is calculated in S110 to S120 in the same manner as S50 to S60, and the generator having the maximum index is determined in S70. We add to electric control candidate. Here, when all the electric control effect indexes Tn ′ are equal to or less than the specified value in S120, an electric control insufficient message is displayed (S130), and the calculation result is output to step S80.
[0042]
When all the electric control effect index values Tn are equal to or less than the specified value in the electric control selection algorithm, there are no additional electric control candidates. For example, even if the index value An for maintaining the transient stability becomes large, Tn becomes zero when the index values Bn and Cn for frequency stability and voltage stability become zero, so the electric generator is not selected. Also, control of maintaining transient stability becomes difficult. Therefore, the above-mentioned switching relaxes the selection conditions for the power generation candidate generator and secures a control amount for system stabilization.
[0043]
Even by switching the effect index as described above, since the frequency stability and the voltage stability maintenance are considered to some extent, the reliability of system stabilization is improved as compared with the conventional individual control.
[0044]
Here, each numerical formula and content of the indices An, Bn, and Cn constituting the electric control effect index Tn will be described. The transient stability effect index An, the frequency stability effect index Bn, and the voltage stability effect index Cn are expressed by Equation 8 and are weighted by the product of one or a plurality of indexes (≧ 0).
[0045]
[Formula 6]
An = A1n × A2n × A3n ×...
Bn = B1n × B2n ×...
Cn = C1n ×...
Among the transient stability effect indicators, the main indicators are described below. The selected absolute condition A1n is an index to be excluded from the control target, and the power generation amount is sufficiently smaller than the rating, the output change of the power generation amount after the occurrence of a system fault is small, or power generation that has already become a power control or power control candidate The target generator is A1n = 0, and other generators are A1n = 1.
[0046]
The generator acceleration index (generator phase angle difference) A2n is an indispensable index that most affects the maintenance of transient stability. The state of the grid affects the fundamental frequency of the grid itself when the generator rotor deviates from the fundamental frequency of the grid. On the other hand, when a system sway occurs due to a system fault, the behavior of the generator is affected by the sway of the system and does not reach a steady state, and stability is lost. Therefore, in order to stabilize the system, it is necessary to disconnect the generator having a large synchronization shift. The generator acceleration index A2n is a value having a weight corresponding to the amount of synchronization deviation between the generator rotor and the system cycle. The specific value of A2n is determined as follows: the generator phase angle difference with respect to the system state is the electric control candidate threshold δ before the stability calculation is terminated. ₀ When the value is exceeded, the value is proportional to the generator phase angle difference with respect to the system state when the value is exceeded.
[0047]
The electric control priority index A3n is an index in which the electric control priority is set for each generator from the operational conditions and generator characteristics, and is calculated as A3n = 1 + α3n from the setting parameter α3n (≧ 0). For example, the priority of generators that take time to start becomes lower.
[0048]
Among the frequency stability effect indexes Bn, an index that influences the frequency stability most is a supply / demand balance index B1n in the assumed separated system. The frequency of the system is operated so as to be in a steady state of the basic frequency (50 Hz / 60 Hz) when the power generation amount and load amount constituting the system are balanced. However, when the system is divided or a load drop occurs due to a system fault, an imbalance occurs in the supply and demand of the system, and the frequency fluctuates.
[0049]
In order to stabilize the system state at the fundamental frequency, it is necessary to balance the supply and demand of the target system. It is possible to reduce the amount of control in the frequency control after the separation system is generated if the control system is implemented so that the supply and demand imbalance in the separation system does not occur for the assumed separation system calculated from the failure point. . Since the supply and demand imbalance in the separated system is the tidal flow that was flowing from the separated system to the main system before the failure occurred, the total output of the control generator exceeds the tidal current that was flowing at the failure point before the failure occurred The index defined in Equation 7 is calculated so that the generator with which the tidal flow rate and the electric control amount are close to each other is selected.
[0050]
[Expression 7]
B1n = a × h (in absolute condition) (or)
B1n ′ = 1 + a × h (priority condition)
However, if PG (SHD (N−1) + Gk) <ΔP,
h = ΔP / (ΔP−PG (SHD (N−1) + Gk))
If PG (SHD (N−1) + Gk)> ΔP,
h = (ΔP−PG (SHD (N−1) + Gk)) / ΔP
Where: a: Supply / demand balance priority parameter in the separated system, Gk: Generator selected as the control candidate in the Nth selection step, SHD (N−1): Control already selected by the (N−1) selection step Generator set, SUB (S): Generator set in assumed separation system S, PG (X): Power generation amount (MW) held by generator set X, ΔP: Current flow from the separation system to this system is there.
[0051]
With reference to the system model of FIG. 4, the example of calculation of the supply / demand balance index B1n in assumption separation system according to the above-mentioned definition is demonstrated. The generator set of the assumed separated system S shown in the figure from the point F of the system where the accident occurs is expressed by Equation 8.
[0052]
[Equation 8]
SUB (S) = {A, B, C, D, E}
Now, assume that A is selected as SHD (1) = {A} as the first electric control candidate. At this time, in order to obtain the supply-demand balance index of the generator B, first, PG ({A, B}), that is, the total power generation amount of the generators A and B is determined in advance before the occurrence of the accident at the point F where the accident occurred. Compare if the tidal flow rate ΔP is smaller. In the illustrated example, since there is a relationship of 100 + 300 <500, the control amount in the separation system does not exceed the pre-tidal flow rate, and B1n is calculated as in Equation 9. a is a setting parameter.
[0053]
[Equation 9]

On the other hand, when the power control amount in the separated system exceeds the prior power flow, B1n is calculated by Equation 10.
[0054]
[Expression 10]
B1n = a x (pre-tide flow rate-control amount in the separation system) / (pre-tide flow rate)
In addition to the indicator B1n, the indicators that can be considered for the frequency stability include the instantaneous separation reserve priority indicator in the assumed separated system, the generator type priority indicator in the assumed separated system, and the electric power generator output dispersion index in the assumed separated system, In this embodiment, the instantaneous power reserve reserve index B2n in the separated system is used.
[0055]
For example, the instantaneous reserve capacity of the generator means an adjustment force for frequency fluctuation. B2n is an index for the purpose of selecting an electric power generator so that the instantaneous reserve capacity in the separated system remains above a predetermined value, and is calculated by Equation 11.
[0056]
[Expression 11]
B2n = i × Gn (in absolute condition) (or)
B2n ′ = 1 + i × Gn (priority condition)
However, when GF (SUB (S) −SHD (N−1) −Gk)> CONST, Gn = 1
If GF (SUB (S) −SHD (N−1) −Gk) <CONST, Gn = 0
Here, i: instantaneous power reserve reserve parameter in the separated system, CONST: constant (setting parameter), Gk: generator that is a candidate for control in the Nth selection step, SHD (N−1): (N−1 ) Electric generator set selected up to the first selection step, SUB (S): generator set in the assumed separation system S, GF (X): governor-free amount (%) held by the generator set X .
[0057]
Among the voltage stability effect indexes Cn, there is a reactive power margin priority index C1n as an index that most affects the voltage stability. The reactive power margin of the generator means an adjustment amount that can maintain a voltage by preventing a voltage drop, and the index C1n aims to leave this adjustment amount in the system. The index C1n is obtained as follows so that the total value of the reactive power margin in the target system is equal to or greater than a specified value.
[0058]
The reactive power margin of the generator uses the generator possible output curve (MEL curve), finds the maximum invalid output from the generator possible output curve (MEL curve) and the valid output before the failure occurs, and finds the maximum reactive output obtained Subtract the reactive power before the failure from, and use it as the reactive power margin. This condition is formulated as follows.
[0059]
Gk: generator that has become a candidate for control at the Nth selection step, SHD (N-1): set of control generators selected by the (N-1) th selection step, SUB (S): target system S Generator set, RQ (X): Reactive power margin (%) held by generator set X, q: Reactive power margin priority parameter in target system, CONST: Constant (setting value) Ask.
[0060]
[Expression 12]
Cn = q × Gn (in absolute condition) (or)
Cn ′ = 1 + q × Gn (priority condition)
However, when RQ (SUB (S) -SHD (N-1) -Gk)> CONST, Gn = 1
If RQ (SUB (S) −SHD (N−1) −Gk) <CONST, Gn = 0
FIG. 5 shows a management table of control effect index values and control generator candidates. The illustrated example shows a process of selecting a control candidate generator from the generators G1 to Gn in the target system. In this embodiment, A1n, A2n, A3n are used as the transient stability effect index An, B1n, B2n are used as the frequency stability effect index Bn, and C1n is used as the voltage stability effect index Cn. Calculated as product. As shown in the figure, the generator G1 is already a candidate for electric control with A1n = 0 and T1 = 0. In this calculation, the power control effect index T2 of the generator G2 is the highest, 120, and is selected as a power control candidate.
[0061]
FIG. 6 shows a comparative example of system stabilization control between the present embodiment and the conventional example. (A) is a system model (accident sequence) to be examined, and a case where a system accident (ground fault) occurs at point P is examined. (B) shows a comparison table of control results.
[0062]
In the conventional system stabilization control, when an accident occurs, first, transient stability calculation control and then frequency stability calculation control are individually performed. If the power control amount necessary for maintaining the transient stability is calculated as 300 MW in the accident at point P, the generator G1 (400 MW) of the F power plant is selected as the optimal power generator.
[0063]
Next, if the system is divided at point P due to a progressive failure, the supply / demand imbalance amount is +300 MW (excess amount of power generation) in the separated system indicated by the dotted line, and therefore 300 MW electric control is required. However, since G1 has already been controlled, G2 (700 MW) of the F power plant with the next smallest control amount is controlled. As a result, the supply / demand imbalance amount becomes −400 MW in the separated system, resulting in a shortage of supply. Therefore, the load limit (400 MW) of the B substation is implemented in the next frequency stability maintenance control. After all, in the conventional control method, the F power plant G1 by the transient stability maintenance control and the F power plant G2 by the frequency stability maintenance control are performed twice, the total control amount is 1100 MW, and the frequency stability The negative control of B substation by maintenance control is performed once, and the control amount becomes 400 MW.
[0064]
On the other hand, in the system stabilization control of the present embodiment, G2 (700 MW) of the F power plant is selected as the optimal power control candidate from the calculation of the integrated electric effect index at the time of the accident at the first P point. . This is because the pre-tidal flow before the accident at point P is 700 MW, and the transient stability can be stabilized at 300 MW. Therefore, the value of the supply / demand balance index Bn in the assumed separated system for F power plant G2 increases, and the integrated power This is because the value of G2 is the largest as the braking effect index Tn. As a result, even if the system is divided at point P due to a developmental failure, the supply and demand balance of the separated system is maintained, so that there is no out-of-step in each generator in the system. There is no longer a need for a system or a negative system. As a result, the control amount and the number of times of control can be greatly reduced as compared with the conventional method.
[0065]
【The invention's effect】
According to the power system stabilization control device of the present invention, it is possible to control the frequency stability of the system, and further to maintain the transient stability in cooperation with the voltage stability, and the control amount and the number of control times for system stabilization. Can be greatly reduced. In addition, since the optimum control target can be selected from many viewpoints for system stabilization, the reliability of the system can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a power system stabilizing device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing an outline of system stabilization control according to the present invention.
FIG. 3 is a flowchart showing an example of a processing procedure of system stabilization control according to the present invention.
FIG. 4 is a system diagram showing a method for calculating a supply and demand balance index in an assumed separated system.
FIG. 5 is a data configuration diagram of a management table of control effect index values and control generator candidates.
FIG. 6 is an explanatory diagram comparing the present embodiment of the system stabilization control with a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Central processing unit, 20 ... Transmission path, 30 ... Information collection terminal, 40 ... Control terminal, 101 ... System stabilization control calculating part, 102 ... Integrated electric control effect parameter | index calculating part.

Claims (5)

System operation information including accident information is input, and a generator suitable for power supply restriction (hereinafter referred to as electric control) necessary for stabilization is determined from the system's transient stability obtained based on the information in the event of a system failure. In the power system stabilization device that selects and outputs the shutdown command of the selected generator,
In order to select a generator (hereinafter referred to as a “electric generator”) necessary for the power source limitation, an index effective for maintaining the transient stability of the system (hereinafter referred to as a transient stability effect index) and an effect effective in maintaining the frequency stability Each index value of a certain index (hereinafter referred to as frequency stability effect index), or the transient stability effect index, the frequency stability effect index, and an index effective in maintaining voltage stability (hereinafter referred to as voltage stability effect index) Is calculated for each generator in the system, an integrated control effect index value is calculated based on the calculated index values, and the generator having the highest control effect index value is selected as a control candidate. Providing a candidate selection means,
When it is determined that the power generation candidate generator is separated from the grid and the system can be stabilized, the power generator is selected as the power control generator, and it is determined that the system cannot be stabilized. In this case, the power system stabilizing device is characterized in that selection of the control candidates by the control candidate selection means is repeated in order to select an additional control generator. In claim 1,
The power control effect index value is obtained by a product of the transient stability effect index and a frequency stability effect index or a product of the voltage stability effect index and the voltage stability effect index. In claim 1 or 2,
The transient stability effect index includes a product of a generator acceleration index that makes it easier to select a generator with a higher out-of-step tendency,
The frequency stability effect index is set so that the total output of the electric generator does not exceed the tidal flow that was flowing to the accident point before the accident in the assumed separation system created from the accident point, and A power system stabilizing device including a supply and demand balance index that makes it easier to select a generator having a closer output. In claim 1, 2 or 3,
The electric control candidate selection means, when it is determined that the electric control effect index value is less than or equal to a specified value for all the generators in the system, and the stabilization of the system is impossible,
The frequency stability effect index, or each of the index values of the frequency stability effect index and the voltage stability effect index is calculated for each generator in the system using an arithmetic expression relaxed so as not to be equal to or less than the specified value. Electric power characterized by calculating an index value, calculating an integrated electric control effect index value based on each calculated index value, and selecting a generator having the highest electric control effect index value as an electric control candidate System stabilization device. In claim 1, 2, 3 or 4,
If the power system stabilizing device is pre-selected and stored from the transient stability of the system for each assumed accident before the occurrence of a system fault, and stored, Then, before or after shutting down the electrical generator stored for the relevant accident, the system transient stability is obtained based on the grid operation information after the grid fault, and the system stability is determined from the transient stability. When it is determined that the electric power generation candidate is not possible, the electric power system stabilization device performs selection of the electric power control candidate by the electric power control candidate selection unit in order to select an additional electric power generator.

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