JP2007209085A - System stabilization control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a desired system stabilization control device of each power plant control system stabilization without using a terminal device and a transmission channel. <P>SOLUTION: The system stabilization system is constituted such that: power plant bus bars BA, BB are connected via cables to an intermediate bus bar B4 connected to a main system via a cable, respectively; the system stabilization control devices 10A, 20B are arranged in a plurality of the power plants 1, 2, respectively, which are constituted of a plurality of generators connected to the power plant bus bars via blockers CB, respectively; the own system stabilization control device of each power plant is autonomously operated when an accident occurs in the cable; and the plurality of generators in the self power plant are controlled so as to selectively be cut off from the power plant bus bar of the self power plant by the blockers. It is determined whether each system stabilization control device is in a mode that the generator in the self power plant is cut off from an electricity amount at a self-end in the occurrence of the accident, and when it is determined that the device in not in the mode that the generator of the self power plant is cut off, the generator cut-off control of the self power plant is locked. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  This invention arises at the time of a serious accident by shutting down the minimum necessary generators at the time of an accident in a power system that supplies power to a main system from a plurality of power plants configured by a plurality of generators via a transmission line. The present invention relates to a so-called system stabilization control system that suppresses an unstable phenomenon.

  The basic system stabilization control system is the non-patent document T.IEEJapan, Vol.110-B, No.8, '90, pages 652-661. It is shown in "Development of method".

In this system stabilization control method, as shown in the flow diagram of FIG. 5 using the power phase difference angle counts P ₁ and P ₂ representing the characteristics of the power system, the following equations (10) and (11) P ₁ ^* and P ₂ ^* which are P ₁ and P ₂ calculated online based on the above are calculated (step ST51).

Next, acceleration energy V _k (also referred to as kinetic energy) and deceleration energy V _c (also referred to as critical energy) are calculated from the following equations (1) and (12) (step ST52).

Next, it is determined whether V _k <V _c, that is, whether it is stable (step ST53). If the result of determination in step ST53 is YES, that is, if it is stable, the generator is not selectively cut off (stop in the flowchart of FIG. 5). If the result of determination in step ST53 is NO, that is, if unstable, the process proceeds to the next step ST54.

In step ST54, the control pattern with the minimum MW amount is selected. That is, the control pattern of the stabilized minimum control amount MW that is the smallest generator selective cutoff amount is selected.
Then, the following (20), (21) P ₁ ^* generator is selected cutoff _P 1 after assumed, _{P 2} from the equation ', P ₂ ^*' is calculated (step ST55).

Next, V _k ′, which is the acceleration energy (kinetic energy) after assuming the generator selection interruption, and the deceleration energy (critical energy) V _c ′ after assuming the generator selection interruption are calculated from the following equations (22) and (23). (Step ST56).

Next, it is determined whether or not V _k ′ <V _c ′ after the generator selection cutoff is assumed, that is, whether or not it is stable (step ST57). If the result of determination in step ST57 is YES, that is, if it is stable, the generator of the selected control pattern of the minimum control amount MW is shut off (step ST59). If the result of determination in step ST57 is NO, that is, if unstable, the process proceeds to the next step ST58.

  In step ST58, the control pattern with the next largest MW amount is selected, and the process returns to step ST55 described above.

  According to the operation flow of steps ST51 to ST59 as described above, so-called system stabilization control is performed in which the minimum necessary generators are shut off and an unstable phenomenon is suppressed in the event of an accident.

  Although the degree of system stabilization effect by separating the generator for each power plant differs depending on the situation of the accident, the system stabilization control system of Non-Patent Document 1 does not take that into consideration. In addition, when performing system stabilization control, there is also a system stabilization system that uses partner terminal information using a terminal device and a transmission line (see Japanese Patent Laid-Open No. 8-33208 (Patent Document 1)).

"Development of on-line stabilization control method for large-capacity power supply system", Transactions of the IEEJ Transaction B, The Institute of Electrical Engineers of Japan, August 1990, Vol. 110-B, no. 8, 652-661 Japanese Patent Laid-Open No. 8-33208 (FIGS. 1, 4 and descriptions thereof)

In the system stabilization method described in Patent Literature 1, since the other end information is used, a terminal device and a transmission path for transmitting the other end information to the own end are necessary.
An unstable phenomenon that occurs in the event of a serious accident by shutting off the minimum required number of generators at the time of an accident in a power supply system that supplies power to the main system from a plurality of power stations composed of multiple generators via a transmission line. In the so-called system stabilization control system for the power supply system to be suppressed, it is preferable that the system stabilization control apparatus of each power plant can perform the intended system stabilization control without using a terminal device and a transmission line.

  The present invention has been made in view of the above-described circumstances, and enables the system stabilization control device of each power plant to perform an intended system stabilization control without using a terminal device and a transmission line. It is intended.

  In the system stabilization control system according to the present invention, a power plant bus is connected to an intermediate bus connected to a main system via a power transmission line, respectively, and a power plant bus is connected to the power plant bus via a circuit breaker. A system stabilization control device is provided in each of a plurality of power plants composed of a plurality of generators, and the system stabilization control device operates in each power plant when an accident occurs in a transmission line. A system stabilization control system that performs control to selectively disconnect a plurality of generators from the power plant bus of the own power plant with a circuit breaker, wherein each system stabilization control device It is determined whether or not it is a mode for controlling the generator at its own power plant from the amount of electricity, and if it is determined that it is not a mode for controlling the generator at its own power plant, it is locked. System A reduction control system.

  The present invention provides a plurality of generators in which a power plant bus is connected to an intermediate bus connected to a main system via a power transmission line via a power transmission line, and is connected to the power plant bus via a circuit breaker. Each of the plurality of constructed power plants is provided with a system stabilization control device, and when an accident occurs in a transmission line, the system stabilization control device operates at each power plant, and a plurality of generators in the power plant are automatically installed. A system stabilization control system that performs control to selectively disconnect from the power plant bus of the power plant by a circuit breaker, wherein each system stabilization control device determines the power of the power plant from the amount of electricity at its own end during the occurrence of the accident. Since it is determined whether or not it is a mode for controlling and disconnecting the generator, and it is determined that it is not a mode for controlling and disconnecting the generator at the own power plant, the generator separation control at the own power plant is locked. Use with No system stabilizing control device of each power station is effective to perform system stabilization control.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram showing an example of the configuration of a power system that supplies power to a main system via a transmission line from a plurality of power plants composed of a plurality of generators, and FIG. 2 is an operation flow of the system stabilization control system. FIG. 3 is a diagram showing an example of the state at the time of the occurrence of a near-end accident, (a) shows the location of the accident and various electrical quantities on a simplified system diagram, and (b) shows each part The relationship between the electrical quantities is shown in a vector diagram. FIG. 4 is a diagram showing an example of a power oscillation mode determination operation flow. 1 to 5, the same reference numerals indicate the same parts.

  As shown in FIG. 1, A power plant 1 is an existing thermal power plant of an electric power company, for example, and is composed of a plurality of, for example, large-capacity class generators GA1... GAn. This is a new power generation facility such as an (independent power generation company), and is composed of a plurality of, for example, small and medium capacity class generators GB1 to GBn.

  The generators GA1... GAn of the A power plant 1 are all connected to the power plant bus BA via individual circuit breakers CB, and the generators GB1. Is connected to the power plant bus BB.

  The A power plant 1 is provided with a system stabilization control device 10A, and the B power plant 2 is also provided with a system stabilization control device 20B.

  The system stabilization control device 10A has a self-end online voltage that is an output of a PT (instrument transformer) connected to each generator bus BGA1... BGAn of the generator GA1. CT output (self-end online current), which is current, is input via the input / output device I / O, and the calculation of each of the above formulas and each of the formulas described below is performed by the calculation device 10A1, and a serious accident such as a power line accident When it is predicted that sometimes an unstable state will occur, the circuit breakers CB,... CB corresponding to each generator are selectively tripped, and the generators GA1,. Control to be.

  The system stabilization control device 20B has a self-end online voltage that is an output of a PT (instrument transformer) connected to each generator bus BGB1 ... BGBn of the generator GB1 ... GBn, an output of each generator. CT output (self-end online current), which is current, is input via the input / output device I / O, and the arithmetic unit 20B1 calculates the above formulas and the formulas described below, causing serious accidents such as power line accidents. When it is predicted that sometimes an unstable state will occur, the circuit breakers CB,... CB corresponding to each generator are selectively tripped, and the generators GB1. Control to be.

  That is, both the system stabilization control device 10A and the system stabilization control device 20B autonomously perform the stabilization control operation by the online electric quantity at the other end without inputting the electrical quantity information at the other end. However, what is different from the prior art is that both the system stabilization control device 10A and the system stabilization control device 20B have a power oscillation mode (depending on the accident point and the generator acceleration / deceleration state) A mode in which it is determined whether or not it is a mode in which the generator of the own power plant is separated and controlled from a plurality of reference modes for determining the necessity of stabilization control at its own end, and the generator of the own power plant is separated and controlled. If it is determined that it is not, the generator disconnection control of the own power plant is locked. Details of this mode determination will be described in detail with reference to FIGS.

  The A power plant 1 and the B power plant 2 are each connected to an intermediate bus B4 such as a substation bus via two separate transmission lines F31 and F32, and further via a two-line transmission line F5. It is connected to a substation bus B6 corresponding to a connection point with the main system.

  Next, the operation will be described with reference to FIGS.

  First, it is determined whether or not it is a control lock based on the result of determination of the power oscillation mode (described in detail later with reference to FIGS. 3 and 4) (step ST220).

  If the determination result in step ST220 is NO, that is, if the stabilization control is continued rather than the control lock, each of the stabilization control devices 10A and 20B sequentially executes steps ST51 to ST59 described above with reference to FIG. .

  If the determination result in step ST220 is YES, that is, if the control is locked, the stabilization control calculation is stopped (stop in the flowchart of FIG. 2).

  Next, calculation of various quantities used for the power oscillation mode determination will be described below.

In the power fluctuation mode determination method, as an index value that can be calculated from the self-end information (P, Q, V),
・ Distance Xc from own end to lowest voltage point (usually accident point) F1
・ Phase difference δ from own end to intermediate bus B4
Is used. These distance Xc and phase difference δ are calculated in a vector diagram as shown in FIG. The calculation formulas are as shown in the following formulas (26) and (27).

(1) Distance Xc from own end to lowest voltage point (usually accident point) F1
The distance Xc from the own end to the lowest voltage point (usually an accident point) F1 is calculated as follows from the vector diagram of FIG. Since the lowest voltage point during the accident is equivalent to the accident point F1, it can be easily determined whether the accident is a near-end accident or not by Xc.

(2) Phase difference δ from own end to intermediate bus B4
The phase difference δ from the own end to the intermediate bus B4 is calculated as follows from the vector diagram of FIG. From this phase difference δ, the tendency of the self-generator phase angle at the time of stability determination by the system stabilization control logic (for example, 210 ms after the occurrence of the accident) can be grasped.

(3) Intermediate bus voltage V2
When calculating the phase difference δ in the above item (2), the intermediate bus voltage V2 is required. This intermediate bus voltage V2 can be calculated only from its own end information as shown in the following equation (28).

  Next, the basic concept of the system stabilization control logic lock condition determination method (reference) will be described with reference to FIG. 4 showing an example of the power oscillation mode determination operation flow.

  A method of simply grasping the electrical distance from the own end to the lowest voltage point from the distance Xc shown in the item (1), and from the own end to the intermediate bus B4 shown in the items (2) and (3). A technique (standard) for determining the lock condition of the system stabilization control logic is constructed by combining techniques capable of grasping the tendency of the self-generator phase angle from the phase difference δ. FIG. 4 shows a determination operation flow of this method (reference).

  As shown in FIG. 4, the value of X used for calculating δ varies depending on the accident section. That is, in the case of an accident on the own line, one line is opened after the accident is removed, so the reactance value is doubled. Considering this point, two kinds of δ are calculated when X and 2X are used for reactance from the own end to the intermediate bus B4.

  In FIG. 4, α is a margin for determination of an accident near the own end and an accident near the intermediate bus, δ (X) is a phase difference from the own end to the intermediate bus B4 when the reactance from the own end to the intermediate bus B4 is X, δ (2X) is a phase difference from the own end to the intermediate bus B4 when the reactance from the own end to the intermediate bus B4 is 2X.

  Next, the mode determination method for the lock condition of the system stabilization control logic will be described below along the flow of FIG.

First, the first step ST41 will be described.
In this step ST41, it is determined whether or not there is a near-end accident based on the magnitude relationship between Xc and X-α.
Xc represents the electrical distance from the own end to the accident point. If this value is smaller than the reactance X to the intermediate bus B4, it is determined that the near end accident has occurred. However, after the accident is removed, there are cases where the value of X changes due to the opening of the line, so Xc during the accident will be used.
Further, in this method, in order to avoid misjudgment of an accident near the intermediate bus as a near-end accident, α is provided as a margin and X−α is used instead of X. This α is determined by a case study.
If it is determined in step ST41 that the near-end accident has occurred, the main control logic of the system stabilization control logic is validated, that is, the control with the system stabilization control logic is continuously executed.
If it is not determined that the near-end accident has occurred in step ST41, the process proceeds to next step ST42.

Next, step ST42 will be described.
In step ST42, it is determined whether or not there is a far accident based on the magnitude relationship between Xc and X-α.
Xc represents the electrical distance from the terminal to the accident point. When this value is larger than the reactance X to the intermediate bus B4, it is determined that the accident is a far accident. In this determination as well, the accidental Xc is used as in step ST41.
Moreover, in this method, in order to avoid misjudgment of an accident near the intermediate bus as a far accident, α is provided as a margin, and X−α is used instead of X. This α is determined by a case study. As a result of the case study, α in this step ST42 may need to be different from α in step ST41.
If it is determined in this step ST42 that there is a far accident, the process proceeds to step ST43. Otherwise (at the time of an accident near the intermediate bus B4), the process proceeds to step ST44.

Next, step ST43 will be described.
In this step ST43, it is determined whether or not the self-generator is accelerating based on whether δ (X) is positive or negative.
This step ST43 is a determination at the time of a far accident, and since there is no opening of the own line due to the accident removal, the reactance of the own line does not change before and after the accident and becomes X. For this reason, the tendency of the self-end generator phase angle is determined using δ (X), and when accelerating, the main control logic of the system stabilization control logic is valid, that is, the system stabilization control logic If the control is continuously executed and the vehicle is decelerating, the system stabilization control logic is locked.

Next, step ST44 will be described.
In this step ST44, it is determined whether or not the self-generator is accelerating based on whether δ (X) and δ (2X) are positive or negative.
In this step ST44, it is a case that is neither a self-end accident nor a far-end accident, that is, an accident near the intermediate bus B4, and the reactance of the own line may change before and after the accident. In other words, in the case of an accident near the intermediate bus on the other line, the reactance does not change with X, but in the case of an accident near the intermediate bus on the own line, the reactance changes to 2X after the accident is removed. Therefore, since it is difficult to determine which of δ (X) and δ (2X) is appropriate, the self-end generator phase angle is determined using these variables δ (X) and δ (2X). The tendency is to be determined.
That is, specifically, when both variables δ (X) and δ (2X) are negative, it is determined that the self-generator is decelerating, and the control by the system stabilization control logic is locked. In cases other than when both variables δ (X) and δ (2X) are negative, the self-generator is not decelerated, and the main control logic of the system stabilization control logic is valid. Continue to execute the control with the stabilization control logic.

  As described above, the mode determination of the lock condition is performed by combining the method for calculating the electrical distance to the lowest voltage point in steps ST41 and ST42 and the method for grasping the tendency of the end-generator phase angle in steps ST43 and ST44. Thus, whether the system stabilization control logic is locked or continuously executed is determined by each system stabilization control device 10A, 10B of each power plant 1, 2 only by its own electrical quantity information, Judgment is made autonomously including the judgment of whether or not the mode is the local mode.

  As can be seen from the above description, in FIG. 4, A is a local mode of its own end, and system stabilization control is performed (system stabilization control is not locked), and B is an overall system mode and system stabilization control is performed. (Does not lock system stabilization control), C locks system stabilization control because of local mode of other power plants, D does not know mode but performs system stabilization control due to acceleration tendency (system stabilization control E) means that the mode is unknown but the system stabilization control is locked due to the apparent deceleration tendency.

  As can be seen from the above description, in the first embodiment, the power generation buses BA and BB are connected to the intermediate bus B4 connected to the main system via the transmission line F5 via the transmission lines F31 and F32, respectively. System stabilization control devices 10A and 20B are provided in each of a plurality of power plants 1 and 2 composed of a plurality of generators connected to the power plant buses BA and BB via circuit breakers CB, respectively. When an accident occurs in a power transmission line, each of the power plants 1 and 2 has its own system stabilization control device autonomously operated, and a plurality of generators in the power plant are disconnected from the power plant bus of the power plant. It is a system stabilization control system that performs control to selectively disconnect by CB, and each system stabilization control device is a mode in which the generator at the own power plant is separated and controlled from the amount of electricity at its own end during the occurrence of an accident. Power generation at the power plant Is a system stabilization control system that locks the generator disconnection control of the own power plant when it is determined that it is not in the mode for controlling the isolation of the power plant, and the system stabilization control device of each power plant is autonomous without using terminal devices and transmission lines. This is a system stabilization control system that can perform the desired system stabilization control.

  Further, as can be seen from the above description, in the first embodiment, each of the system stabilization control devices 10A and 20B is a near-end accident due to the amount of electricity at its own end. Is a system stabilization control system that continues the generator disconnection control of the own power plant when it is determined that the mode is the control mode for disconnecting the generator.

  Further, as can be seen from the above description, the first embodiment is that each of the system stabilization control devices 10A and 20B reaches when the reactance from its own end to the lowest voltage point during an accident is smaller than a predetermined value. This is a system stabilization control system that determines that a near-end accident has occurred.

Further, as can be seen from the above description, the first embodiment is effective in that the reactance from the self-end to the lowest voltage point during the accident is Xc, the self-end voltage during the accident is VT, and the self-end voltage during the accident flows from the self end. When the power is P and the reactive power flowing from the own end during the accident is Q, the reactance Xc from the own end to the lowest voltage point during the accident is expressed as Xc = VT ² * Q / (P ² + Q ² ) The system stabilization control system calculated by each of the system stabilization control devices 10A and 20B.

  Further, as can be seen from the above description, in the first embodiment, each of the system stabilization control devices 10A and 20B has its own-end generator accelerating from the amount of electricity at its own end during an accident. When it determines with it being the mode which isolate | separates and controls the generator of an own power plant, it is a system | strain stabilization control system which continues the generator isolation | separation control of the said own power plant.

  Further, as can be seen from the above description, in the first embodiment, each of the system stabilization control devices 10A and 20B has a phase angle difference δ from its own end to the intermediate bus B4 during an accident from a predetermined value. This is a system stabilization control system that determines that the vehicle is accelerating when it is large.

Further, as can be seen from the above description, the first embodiment is configured such that the phase angle difference from the own end during the accident to the intermediate bus is δ, the intermediate bus voltage during the accident is V2, and from the own end during the accident. When the reactance to the intermediate bus is X, the phase angle difference δ from the own end to the intermediate bus during the accident is expressed as δ = cos ⁻¹ [{VT ² + V ^{2 2} −X ² * (P ² + Q ² ) / VT ² } / (2 * VT * V2)]. The system stabilization control system is calculated by each of the system stabilization control devices 10A and 20B.

  Note that the mode determination method of the lock condition of the system stabilization control logic according to the flow of FIG. 4 described above is not limited to the case where there are two power plants sharing the intermediate bus, but can also be applied when there are three or more power plants. .

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows Embodiment 1 of this invention, and is a figure which shows the example of a structure of the electric power system which supplies electric power to a main system via a power transmission line from the some power plant comprised with the several generator. It is a figure which shows Embodiment 1 of this invention, and is a figure which shows the example of the operation | movement flow of a system | strain stabilization control system. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows Embodiment 1 of this invention, and is a figure which shows the example of the state at the time of near-end accident occurrence, (a) shows an accident occurrence location and various electrical quantities on a simplified system diagram, ) Shows the relationship between the electrical quantities of each part in a vector diagram. It is a figure which shows Embodiment 1 of this invention, and is a figure which shows the example of an electric power oscillation mode determination operation | movement flow. It is a flowchart which shows the conventional typical system | strain stabilization control system.

Explanation of symbols

F5 Transmission line to the main system,
B4 Intermediate bus,
F31, F32 Transmission line to intermediate bus,
BA, BB power plant bus,
CB circuit breaker,
1,2 power plant,
10A, 20B System stabilization control device.

Claims (7)

  A plurality of generators composed of a plurality of generators each connected to a power plant bus via a power transmission line and an intermediate bus connected to the main system via a power transmission line, and connected to the power plant bus via a circuit breaker, respectively. Each of the power stations is provided with a system stabilization control device, and when an accident occurs in the transmission line, the system stabilization control device operates at each power plant, and a plurality of generators in the power plant are connected to the power plant. A system stabilization system that performs control to selectively disconnect from a power station bus using a circuit breaker, and each system stabilization control device separates and controls the generator of the power station from the amount of electricity at the end of the accident. A system stabilization control system that determines whether or not the mode is a mode to perform, and locks the power generator disconnection control of the power plant when it is determined that the mode is not a mode for disconnecting and controlling the power generator of the power plant.   2. The system stabilization control system according to claim 1, wherein each of the system stabilization control devices is in a mode in which a near-end accident is detected from an amount of electricity at its own end and a generator of the own power plant is separated and controlled. If it is determined, the system stabilization control system continues the generator disconnection control of the power plant.   3. The system stabilization control system according to claim 2, wherein each of the system stabilization control apparatuses determines that a near-end accident occurs when a reactance from the local end to the lowest voltage point during the accident is smaller than a predetermined value. A system stabilization control system characterized by that. 4. The system stabilization control system according to claim 3, wherein the reactance from the self-end to the lowest voltage point during the accident is Xc, the self-end voltage during the accident is VT, the active power flowing from the self-end during the accident is P, the accident When the reactive power flowing from its own end is Q, reactance Xc from its own end to the lowest voltage point in the accident is expressed as Xc = VT ² * Q / (P ² + Q ² ) A system stabilization control system characterized in that the control system calculates.   2. The system stabilization control system according to claim 1, wherein each of the system stabilization control devices separates the power generator at the power plant because the power generator at the power plant tends to accelerate from the amount of electricity at the power plant during the accident. A system stabilization control system characterized in that when it is determined that the control mode is set, the generator disconnection control of the power plant is continued.   6. The system stabilization control system according to claim 5, wherein each of the system stabilization control apparatuses determines that an acceleration tendency is present when a phase angle difference from the own end during the accident to the intermediate bus is greater than a predetermined value. A system stabilization control system characterized by that. 7. The system stabilization control system according to claim 6, wherein a phase angle difference from the own end to the intermediate bus in the accident is δ, an intermediate bus voltage in the accident is V2, and the own bus to the intermediate bus is in the accident. When the reactance is X, the self-end voltage during the accident is VT, the active power flowing from the self-end during the accident is P, and the reactive power flowing from the self-end during the accident is Q, the intermediate bus from the self-end during the accident Phase angle difference δ up to δ = cos ^-1 [{VT ² + V ^{2 2} −X ² * (P ² + Q ² ) / VT ² } / (2 * VT * V 2)] A system stabilization control system characterized in that the control device calculates.

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