JP5863349B2 - System stabilization control system - Google Patents

Description

  The present invention is configured to be applicable to an electric power system (hereinafter simply referred to as “system”) including a plurality of power plants composed of a plurality of generators, and an accident or failure that has occurred in the system (hereinafter simply referred to as “accident”). It relates to a system stabilization control system for stabilizing the power system by performing generator control according to the situation of).

  For example, when an accident such as a lightning strike occurs in a device (such as a power transmission line) constituting the system, the synchronization of the generator cannot be maintained and a step-out may occur. Various system stabilization control systems that can cope with such generator out-of-step phenomena have been developed. The calculation methods in this type of system can be broadly classified as “pre-calculation method” and “post-calculation calculation”. "Method".

  The pre-calculation method is a method in which a control amount for a system fault assumed in advance is calculated in advance, and has an advantage that quick control can be performed when a system fault occurs. On the other hand, the post-calculation method is a method of measuring an actual system phenomenon after the occurrence of a system fault and calculating a control amount based on the measured electric quantity, and has an advantage that it can flexibly cope with various events.

  In addition, there exists a system | strain stabilization control method shown by the following patent document 1 as a prior art which uses a prior | preceding calculation method and a post-calculation method. In this system stabilization control method, the power flow value, etc. is grasped from the voltage / current sensor, and when an accident occurs, the accident type is grasped from the power flow value immediately before the accident and the accident information after the accident, and the power phase difference curve When it can be estimated by a so-called “P-Δδ curve” (also referred to as “P-δ curve”), control is performed based on the control amount calculated by this P-δ curve (control by a post-calculation method). When it is difficult to estimate the P-δ curve, control using the necessary stabilization control table determined in advance (control by a prior calculation method) is performed.

JP 2002-34156 A

  According to the system stabilization control method disclosed in Patent Document 1, control using a power phase difference angle curve (P-δ curve) (control by a posterior calculation method) and control using a control table determined in advance ( By performing control that switches between control according to a pre-computation method according to a predetermined condition, high-speed and high-precision control that flexibly corresponds to the state of the accident is possible. However, in the future, it is expected that the flow of liberalization of electric power supply and deregulation will be accelerated, system facilities will be complicated, and the situation of system accidents may be diversified. For this reason, in the system stabilization control method using both the pre-calculation method and the post-calculation method, further improvement in control speed and control accuracy is desired.

  The present invention has been made in view of the above, and effectively combines the high speed, which is the advantage of the pre-calculation method, with the flexibility, which is the advantage of the post-calculation method, to further improve the control speed and control accuracy. An object of the present invention is to provide a system stabilization control system that can be improved.

  In order to solve the above-described problems and achieve the object, the present invention is configured to be applicable to an electric power system including a plurality of power plants composed of a plurality of generators, and according to the situation of an accident. It is a system stabilization control system that stabilizes the power system by performing control, and controls by a pre-computation method that performs stability determination and control amount calculation for each accident case assumed in advance before the occurrence of the accident, and after the accident Combined with control based on the post-calculation method that performs stability determination and control amount calculation based on measurement information, and constructs each control on the basis of the equal area method. Deceleration using a first curve that is a previous power phase difference angle curve, a second curve that is a power phase difference angle curve after accident removal, and a third curve that is a power phase difference angle curve after reclosing Calculate the energy The correction control calculation by the rear arithmetic method, and calculates the deceleration energy using said first to third curves, and the fourth curve is a power phase angle curve in re failure, the.

  According to the present invention, the high speed that is the advantage of the pre-calculation method and the flexibility that is the advantage of the post-calculation method are effectively fused, and the control speed and the control accuracy can be further improved. .

FIG. 1 is a diagram illustrating a configuration example of a system stabilization control system according to the present embodiment. FIG. 2 is a flowchart showing a schematic flow of pre-arithmetic control. FIG. 3 is a flowchart showing a schematic flow of post-operation control. FIG. 4 is a flowchart showing a processing flow of the main control calculation activated in the preliminary calculation control (see FIG. 2). FIG. 5 is a diagram illustrating an example of a system configuration. FIG. 6 is a diagram illustrating a configuration of a first equivalent model in which the system illustrated in FIG. 5 is simplified. FIG. 7 is a diagram showing a configuration of a second equivalent model obtained by further simplifying the first equivalent model shown in FIG. FIG. 8 is a diagram illustrating an example of a reactance value and a coefficient setting value of a P-δ curve according to the transition state. FIG. 9 is a diagram illustrating an example of coefficient setting values for calculating reactance values in the equivalent model. FIG. 10 is an image diagram showing a concept of energy amount calculation in the main control calculation. FIG. 11 is a diagram showing a concept of energy amount calculation in a case different from FIG. FIG. 12 is a diagram illustrating an image of a control table referred to by the central processing unit. FIG. 13 is a diagram showing an image of a reference table showing a selection order when the generator is shut off. FIG. 14 is a flowchart showing a processing flow of correction control calculation started in post-mortem control (see FIG. 3). FIG. 15 is an image diagram showing a concept of energy amount calculation in the correction control calculation. FIG. 16 is a diagram illustrating an example of coefficient setting values after correction of the power phase difference angle curve in the correction control calculation. FIG. 17 is an image diagram for explaining a modification example (first technique) of the arithmetic processing. FIG. 18 is an image diagram for explaining a modification example (second method) of the arithmetic processing. FIG. 19 is an image diagram for explaining a modification example (third method) of the arithmetic processing.

  Hereinafter, a system stabilization control system according to an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, this invention is not limited by embodiment shown below.

<Embodiment>
(Configuration of system stabilization control system)
FIG. 1 is a diagram illustrating a configuration example of a system stabilization control system according to an embodiment of the present invention. The system stabilization control system of the present embodiment includes a central processing unit 10 and a control terminal 15 (15a to 15n) that operates in response to a command from the central processing unit 10. The central processing unit 10 is disposed, for example, in a predetermined substation 2, and the control terminals 15 (15a-15n) are disposed in a power plant 3 (3a-3n) having a generator. The substation 2 in which the central processing unit 10 is arranged is one arbitrarily selected from a plurality of substations belonging to the same system, but other than the substation, for example, a plurality of substations and power stations are arranged. The central processing unit 10 may be arranged at a power supply command station or the like to be supervised.

  The central processing unit 10 arranged in the substation 2 and the control terminal 15 (15a-15n) arranged in the power plant 3 (3a-3n) are connected by a communication line 18 (18a-18n). The communication line 18 (18a to 18n) is not necessarily a dedicated line as long as a required communication request is satisfied, and a public line or the like may be used.

  In the power plant 3 (3a to 3n), a generator group 4 including various power generation facilities is connected to a bus 6 via a circuit breaker 7. A current transformer 8 and an instrument transformer 9 for measuring the amount of electricity (voltage, current) at important points are provided on the bus 6 or its peripheral part.

(Control flow of the entire system)
FIG. 2 is a flowchart showing a schematic flow of pre-computation control in the system stabilization system of the present embodiment, and FIG. 3 is a flowchart showing a schematic flow of post-operation control in the system stabilization system of the present embodiment. is there. Here, the pre-computation control is control by a pre-computation method that is excellent in high speed, and is also referred to as main control. On the other hand, the post-computation control is a control based on a post-computation method with excellent flexibility. After the pre-computation control, if the control amount is insufficient in the pre-computation control, it is executed following the pre-computation control. Control. This post-computation control is also referred to as correction control.

  Next, with reference to FIG. 2 and FIG. 3, each control flow regarding the pre-computation control and the post-computation control will be described. Note that both the pre-computation control shown in FIG. 2 and the post-computation control shown in FIG. 3 are executed in the central processing unit 10.

(Pre-computation control processing flow)
First, the processing flow of pre-arithmetic control will be described. In FIG. 2, in step S <b> 101, system information is collected by the current transformer 8 and the instrument transformer 9. In step S102, an assumed case (selection pattern of a shut-off generator) is selected by referring to a control table described later. In step S103, a main control calculation process described later is started. In step S104, it is determined whether or not confirmation for all cases (all assumed cases) defined in the control table referred to in step S102 has been completed. If all cases have not been completed (No in step S104). Returning to step S102, if all cases have been completed (step S104, Yes), the process proceeds to step S105. In step S105, the control table is updated based on the calculation result in step S103, and the entire process is terminated. The processing flow of FIG. 2 is activated every predetermined cycle (for example, about 1 second), and it is determined whether or not the control table needs to be updated at each activation, and the control table is updated at predetermined intervals. Maintained in a state.

(Post-processing control flow)
Next, the processing flow of post-mortem control will be described. First, the processing flow of the post-computation control shown in FIG. 3 is started when an activation target accident is detected. After the start-up, in step S201, the main control command is transmitted to the power plant to which the main control command is to be transmitted, that is, the power plant having the cutoff generator instructed in the control table. In step S202, post-event information (system information after the accident) is collected by the current transformer 8 and the instrument transformer 9. In step S203, a correction control calculation process described later is started, and if necessary, a correction control command is transmitted to the corresponding power plant (a power plant having a shut-off generator specified by the correction control calculation). In step S204, it is determined whether or not the set monitoring time has ended. If the monitoring time has not ended (No in step S204), the process returns to step S202, and if the monitoring time has ended (step S204). , Yes), the entire process is terminated.

(Processing flow for main control calculation)
Next, main control calculation, which is a subroutine in the prior calculation control processing flow, will be described with reference to FIGS. 4 to 13. Here, FIG. 4 is a flowchart showing a processing flow of the main control calculation activated in step S103 of the pre-arithmetic control (see FIG. 2). 5 to 13 are drawings to be referred to when the flow of FIG. 4 is described. Specifically, FIG. 5 is a diagram illustrating an example of a system configuration, FIG. 6 is a diagram illustrating a configuration of a first equivalent model in which the system illustrated in FIG. 5 is simplified, and FIG. FIG. 8 is a diagram showing a configuration of a second equivalent model obtained by further simplifying the equivalent model (first equivalent model) shown in FIG. 8, and FIG. 8 shows reactance values according to transition states and coefficient setting values of the P-δ curve. FIG. 9 is a diagram showing an example, FIG. 9 is a diagram showing an example of coefficient setting values for calculating reactance values in the equivalent model, and FIG. 10 is an image diagram showing the concept of energy amount calculation in the main control calculation. 11 is a diagram showing the concept of energy amount calculation in a case different from FIG. 10, FIG. 12 is a diagram showing an image of a control table referred to by the central processing unit 10, and FIG. The order of selection when performing Is a diagram showing an image of the reference table.

(Step S301-power phase difference angle curve estimation)
In step S301, a power phase difference angle curve is estimated. The assumed system configuration is as shown in FIG. Since the state of the bus, power transmission line, transformer, etc. shown in FIG. 5 can be measured at each terminal of the substation, it is possible to obtain the electrical distance in the system. Also, the load amount in the system can be calculated based on information from each terminal. Based on these points, the power phase difference curve is calculated using the following assumptions.

(A) The buses 20a and 20b of the substation 20 are set to infinite buses. Note that the short-circuit impedance between the buses 20a, 20b and the original infinite bus hardly affects the power phase difference curve, and is omitted here.
(B) Each generator of the power plants 25 and 27 is expressed as a model with a constant backside reactance x " _d (x" _{d1 to} x " _d5 ). The next transient reactance x" _d (x " _{d1 to} x There is no problem even if a transient reactance x ′ _d (x ′ _{d1 to} x ′ _d5 ) is used instead of “ _d5 ”.
(C) Assuming that each generator to be controlled moves coherently, nodes corresponding to the Xd ″ behind each generator are aggregated, and these are aggregated as equivalent generators 40 to 44.
(D) Since the reactance (x " _{d1 to} x" _d5 ) inside the generator and the reactances (X _T21 , X _T22 , X _T41 , X _T42 ) of the step-up transformers 45 to 49 are dominant, go to the substation 23 Can be collected as the load of the substation 21.

  Based on the above assumptions (a) to (d), the system model of FIG. 5 can be represented by the simplified system model of FIG.

In FIG. 6, the reactance X ₁ between the infinite bus 31 and the load bus 32 is the reactance X _{T11 to} X _T13 of the step-up transformer 29 (29a to 29c) of the substation 20 and the bus of the substation 20 in FIG. The reactances X _L11 and X _L12 of the transmission line 22 laid between 20b and the bus 21a of the substation 21 are aggregated.

Similarly, the reactance X _2a between the load bus 32 and the equivalent generator output end 33 is the reactance X _{L21 of} the transmission line 28a laid between the bus 21a of the substation 21 and the bus 25a of the power plant 25. X _L22 , X _L31 , X _L32 , reactance X _L61 of the transmission line 28 b laid between the bus 21 a and the bus 27 a of the power plant 27, and between the bus 21 a and the bus 27 b of the power plant 27 The reactance _XL62 of the transmission line 28c is _collected .

Similarly, the reactance X _2b between the equivalent generator output end 33 and the equivalent generator virtual output end 34 corresponds to the reactances X _T21 and X _T22 of the step-up transformers 45 and 46 in the power plant 25 and the equivalent generators 40 and 41. Reactances (next transient reactances) x " _d1 , X" _d2 , reactance _XT41 of the step-up transformer 48 in the power plant 27, next transient reactance x " _{d4 of the} equivalent generator 43, and reactance of the step-up transformer 49 in the power plant 27 _XT42 and the next transient reactance x " _d5 of the equivalent generator 44 are aggregated.

  Further, the system model of FIG. 6 can be further simplified as shown in FIG. In the system model shown in FIG. 7, the values of X and R can be calculated as follows.

According to this system model, the equivalent generator output P _E in the steady state is expressed as a function of the phase angle δ between the voltage EG1 of the equivalent generator virtual output terminal 34 and the voltage EG2 of the infinite bus 31 as follows: It can be expressed as follows.

Here, the above equation (3) is defined as a power phase difference angle curve in the main control. Although the derivation process is omitted, the coefficients P ₀ and P ₁ in the equation (3) can be expressed by the following equations using the voltages EG1 and EG2.

The values of the coefficients P ₀ and P ₁ in the equation of the power phase difference angle curve change depending on the state of the system after the accident. In addition, factors that are difficult to grasp in advance, such as the location of an accident, accident impedance, and accident duration, greatly affect the power phase difference curve during an accident. Therefore, in order to avoid a large excess in the main control, the curve during the accident is not simulated in the main control, and the transition is made in the order before the accident → after the accident removal → before the accident (assuming that the reclosing is successful). Assuming that. Based on such a premise, the coefficient which changes in each state is defined as shown in FIG.

According to FIG. 8, the set values of reactances X ₁ and X ₂ and the calculated values of the coefficients P ₀ and P ₁ that change in accordance with the transition state of the accident (before the accident → after removing the accident → after the reclosing) are shown. Has been. The subscript c attached to the reactance X ₂ and the coefficients P ₀ and P ₁ means that the main control is performed. However, the subscript c is not added to the reactance X ₁ that does not change due to the execution of the main control.

The reactance X ₁ after the accident removal and after the reclosing is calculated by changing the reactance of the transmission line 22. The value of the reactance to be set is set based on a theoretical value or a value obtained from a simulation result in a representative case for each assumed accident case (for each remaining line state). Here, an example of the calculation formula in the normal state is as follows.

A setting example of the coefficient K _XL shown in the above equation (6) is as shown in FIG. In FIG. 9, the meanings of “1L” → “ab−” and “2L” → “a−−” in the second term from the left are the c-phase of the first line of the transmission line 22 and the second line. It means that b phase and c phase are blocked. In the cut-off state, the reactance increases, and therefore, the coefficient K _XL is adjusted as shown in the equation (6). According to the example of FIG. 9, the value of the coefficient K _{XL in} this line state is set to 4.503.

The reactance X ₂ can also be obtained in the same manner as the reactance X ₁ . Detailed description thereof is omitted here are the reactance X ₂ after after the accident removal and re-closure may be theoretically calculated based on the generator connection state after the generator off.

(Step S302—Angular velocity deviation and phase angle calculation)
In step S302, an angular velocity deviation and a phase angle are calculated. Specifically, the angular velocity deviation and the phase angle of the equivalent generator are calculated by solving the equation of motion of the equivalent generator shown in the following equation and the following equation. Here, the output of the equivalent generator is assumed to follow the power phase difference angle curve in each state.

From these equations of motion, the phase angle δ _rc at the reclosing time (t _rc ) and the angular velocity deviation ω _c1 at the main control execution time (t _c1 ) are calculated. The phase angle initial value δ ₀ can be calculated using the following equation based on the power phase difference angle curve in advance. The initial value of the angular velocity deviation is 0.

(Step S303-Energy Value (V _A , V _D ) Calculation)
In step S303, acceleration energy V _A and deceleration energy V _D are calculated. The acceleration energy V _A is calculated as follows based on the angular velocity deviation Δω (t _c1 ) at the main control execution timing.

On the other hand, the deceleration energy V _D can be calculated based on the following equations (11) to (15) after comparing the phase angle at the reclosing time and the phase angle at the unstable equilibrium point.

(A) When a solution of δ _u2 exists (a solution of δ _u1 may or may not exist) and δ _rc <δ _u2

(B) When both solutions of δ _u1 and δ _u2 exist and δ _rc ≧ δ _u2

(C) When both solutions of δ _u1 and δ _u2 do not exist, or when only a solution of δ _u2 exists and δ _rc ≧ δ _u2

For example, FIG. 10 shows an image of energy calculation when the equation (13) is satisfied. In FIG. 10, a curve K1 indicated by a solid line is a power phase difference angle curve (P _E = P ₀₀ + P ₁₀ sin δ) before the accident, and a curve K2 indicated by a broken line is a power phase difference angle curve after the accident is removed. (P _E = P ₀₁ + P ₁₁ sin δ), and a curve K3 indicated by a one-dot chain line is a power phase difference angle curve (P _E = P ₀₂ + P ₁₂ sin δ) after reclosing (assuming successful reclosing). . The meanings of the symbols shown on the vertical axis and the horizontal axis are as follows.

P _M : Total value of generator output δ ₀ : P-δ curve K1 stable equilibrium point (initial phase angle)
δ _c1 : Phase angle when main control is performed δ _rc : Phase angle when reclosing is performed δ _u1 : Unstable equilibrium point of P-δ curve K2 δ _u2 : Unstable equilibrium point of P-δ curve K3

As shown in the drawing, an area V _A between δ _{0 and} δ _c1 sandwiched between a straight line L1 obtained by drawing the generator output total value P _M parallel to the δ axis and the curve K2 corresponds to acceleration energy. Actually, the acceleration energy V _A is calculated using the above-described equation (10).

On the other hand, the area V _D1 + V _D2 (* V _D1 is a negative value) between δ _{c1 and} δ _rc sandwiched between the straight line L1 and the curve K2, and δ _rc −δ _u2 between the straight line L1 and the curve K3. The sum with the area V _D3 corresponds to deceleration energy. The deceleration energy at this time can be calculated using the above equation (13).

  Further, FIG. 11 shows an image of energy calculation when the equation (14) is satisfied. The meanings of the waveforms and symbols shown in FIG. 11 are the same as those shown in FIG.

When δ _rc ≧ δ _u2 , as shown in FIG. 11, an area V _D1 + V _D2 between δ _{c1 and} δ _u1 sandwiched between the straight line L1 and the curve K2 corresponds to deceleration energy. At this time, the deceleration energy can be calculated using the above-described equation (14).

As can be understood from FIGS. 10 and 11, when both the solutions of δ _u1 and δ _u2 do not exist or when only the solution of δ _u2 exists and δ _rc ≧ δ _u2 , these figures are used. The hatched area corresponding to the deceleration energy V _D shown in FIG. Therefore, under these conditions, V _D = 0 can be set as in the above-described equation (15).

(Step S304—Stability Determination (V _A <V _D ))
In step S304, the magnitude relationship between the value of the acceleration energy V _{A and} the value of the deceleration energy V _D is compared. If the deceleration energy V _D is larger than the acceleration energy V _A (step S304, Yes), it is determined that the system is stable, and the process of FIG. 4 is exited without performing the main control. On the other hand, if the deceleration energy V _D is equal to or less than the acceleration energy V _A (step S304, No), the process proceeds to step S305.

(Step S305—control pattern selection)
In step S305, the generator to be controlled is selected, and the tables referred to at this time are shown in FIGS. In the example of the table shown in FIG. 12, the generator shut-off is executed only when the initial accident aspect is 3φ4LG (abc-a) or 3φ4LG (ab-bc). Such processing relies on the idea that the main control response is limited only to severe accidents. In the example of FIG. 12, when the initial accident aspect is 3φ5LG (abc-ab) and 3φ6LG (abc-abc), the generator shut-off is not executed. The reason is as shown in FIG. This is because, in the case of a system having a structure, in the accident aspect of 3φ5LG (abc-ab) and 3φ6LG (abc-abc), the system is always separated, and it is not necessary to perform control to prevent step-out.

  The selection image of the cut-off generator is, for example, as shown in FIG. 13 and is an image in which cut-off generators are sequentially selected from the top of the sorted table in ascending order of the generator capacity.

(Step S306-power phase difference angle curve (after control) estimation)
In step S306, the state of the system after the generator shutoff is grasped, and the power phase difference angle curve is recalculated.

(Step S307-angular velocity deviation, phase angle correction)
In step S307, assuming the state after the generator is shut off, the values of angular velocity deviation and phase angle are recalculated.

(Step S308-energy value (V _A ', V _D ') calculation)
Based on the results of steps S306 and S307, the energy value after the generator is shut off is calculated.

(Step S309-Stability Determination (V _A '<V _D '))
In step S309, the magnitude relationship between the recalculated acceleration energy V _A ′ and deceleration energy V _D ′ is compared. If the deceleration energy V _D ′ is greater than the acceleration energy V _A ′ (Yes in step S309), step S310 is performed. Migrate to On the other hand, if the deceleration energy V _D ′ is equal to or less than the acceleration energy V _A ′ (No at Step S309), the processing from Step S305 is repeated.

(Step S310-Confirmation of control target)
In step S310, the currently selected interruption pattern is determined as a control target in the main control. If there is no other interrupt pattern other than the currently selected interrupt pattern, the shortage is expected in the correction control, and the control object currently selected is determined as the control object in the main control, The process flow of FIG. 4 is exited.

(Processing flow related to correction control calculation)
Next, correction control calculation, which is a subroutine in the post-calculation control process flow, will be described with reference to FIGS. Here, FIG. 14 is a flowchart showing a processing flow of the correction control calculation activated in step S203 of the post-calculation control (see FIG. 3). 15 and 16 are drawings to be referred to when the flow of FIG. 4 is described. Specifically, FIG. 15 is an image diagram showing the concept of energy amount calculation in the correction control calculation, and FIG. 16 is a diagram showing an example of the coefficient setting value of the power phase difference angle curve in the correction control calculation.

  In correction control as a countermeasure for transient stability, a power phase difference curve is obtained based on the pre-computation result corresponding to the accident case that was actually started and the subsequent measurement amount, and stability determination and necessary control amount are performed based on the equal area method. Is calculated. Here, as can be understood from a comparison between FIG. 4 and FIG. 14, the processing flow itself is substantially the same as the main control. However, the correction control calculation is different from the main control for some accident cases in that it is intended for all accident cases for which countermeasures for transient stability are considered necessary. The correction control may be performed a plurality of times at a constant cycle after the occurrence of the accident, but in the following description, the first correction control is described.

(Step S401—Electric Power Phase Difference Curve Estimation)
In the correction control calculation, the power phase difference angle curve is estimated based on the subsequent measurement data. In this estimation process, the following two cases are assumed.

Case 1: Use the values of P ₀ and P ₁ obtained by the main control calculation as they are.
Case 2: The values of P ₀ and P ₁ obtained by the main control calculation are corrected and used.
Details of correction in case 2 will be described later.

(Step S402-Angular Velocity Deviation, Phase Angle Calculation)
In step S402, an angular velocity deviation and a phase angle are calculated. Specifically, the angular velocity deviation and the phase angle of the equivalent generator are calculated by solving the equation of motion of the equivalent generator shown in the following equation and the following equation. In addition, the output of an equivalent generator shall follow the power phase difference angle curve in each state.

The phase angle and angular velocity deviation at the main control time point (t _c1 ), the correction control time point (t _c2 ), the reclosing (failure) time point (t _rc ), and the final cutoff time point (t _rc2 ) are calculated from the above equation of motion. The phase angle initial value δ ₀ can be calculated based on the following equation. In addition, the initial value of the angular velocity deviation is 0 (similar to the main control).

The absolute phase angle calculated by the above equation (17) is actually the absolute phase angle calculated due to the acceleration of the entire system accompanying the accident or the governor operation of the generator. Becomes a value larger than the phase difference from the original counterpart (shifted to the excessive control side). Therefore, for severe cases where control delay is not allowed (assuming a case where it is determined to be unstable in the main control calculation), the absolute phase angle is used as it is (k _d = 1.0) for reliable stabilization. It is desirable to plan. On the other hand, for the case close to the stability limit (here, the case where it is stable or determined to be the stability limit by the main control calculation), the value of k _{d in} the equation (17) is adjusted after the main control execution timing. By doing so, it becomes possible to alleviate the tendency of excessive control.

(Step S403-energy value (V _A , V _D ) calculation)
In step S403, acceleration energy V _A and deceleration energy V _D are calculated. The acceleration energy V _A is calculated according to the following equation based on the angular velocity deviation Δω (t _rc2 ) at the final cutoff time (when the final cutoff time t _rc2 is used as a reference).

On the other hand, the deceleration energy V _D is _calculated by the following equations (20) to (22) after comparing the phase angle δ _rc2 at the reclosing time (re-failure removal time) and the phase angle δ _u2 at the unstable equilibrium point. Can be calculated based on this.

(A) When a solution of δ _u2 exists (a solution of δ _u1 may or may not exist) and δ _rc2 <δ _u2

(B) or the solution of [delta] _u2 is not present, only the solution of [delta] _u2 is present, and if the δ _rc2 ≧ δ _u2

Here, FIG. 15 shows an image of energy calculation when the equation (21) is satisfied. In FIG. 15, a curve K1 indicated by a solid line is a power phase difference angle curve (P _E = P ₀₀ + P ₁₀ sin δ) before the accident, and a curve K2 indicated by a broken line is a power phase difference angle curve after the accident is removed. (P _E = P ₀₁ + P ₁₁ sin δ), and a curve K3 indicated by a one-dot chain line is a power phase difference angle curve (P _E = P ₀₂ + P ₁₂ sin δ) after reclosing (assuming that reclosing is successful). A curve K4 indicated by a two-dot chain line is a power phase difference angle curve during a re-failure. The meanings of the symbols shown on the vertical axis and the horizontal axis are as follows.

P _M : Total value of generator output δ ₀ : P-δ curve K1 stable equilibrium point (initial phase angle)
δ _rc : Phase angle at the time of re-failure δ _rc2 : Phase angle at the time of reclosing (at the time of re-failure removal) δ _u1 : Unstable equilibrium point of P-δ curve K2 δ _u2 : Unstable equilibrium of P-δ curve K3 point

When re-failure removal is used as a reference, as shown by the fine hatching in the figure, the area (V _A1) between the straight line L1 obtained by drawing the generator output total value P _M parallel to the δ axis and the curves K4 and K2 ~ V _A4 ) corresponds to acceleration energy. Actually, this acceleration energy V _A is calculated using the above-described equation (19).

On the other hand, an area V _D sandwiched between the straight line L1 and the curve K3 indicated by rough hatching corresponds to deceleration energy. This deceleration energy can be calculated using the above equation (21).

Incidentally, or if the solution of [delta] _u2 is not present, there is only the solution of [delta] _u2, and in the case of δ _rc2 ≧ δ _u2, the area of the hatching portion corresponding to the deceleration energy V _D shown in FIG. 15 occurs Absent. Therefore, in the case of these conditions, V _D = 0 can be set as in the above equation (22).

(Step S404—Stability Determination (V _A <V _D ))
In step S304, the magnitude relationship between the value of the acceleration energy V _{A and} the value of the deceleration energy V _D is compared. If the deceleration energy V _D is greater than the acceleration energy V _A (step S404, Yes), the system exits the process of FIG. 14 without performing correction control assuming that the system is stable. If the angular velocity deviation at the time of final interruption is a negative value, it may be determined unconditionally that the first shaking wave has already started to decelerate and is unconditionally stable. On the other hand, if the deceleration energy V _D is equal to or less than the acceleration energy V _A (step S404, No), the process proceeds to step S405.

(Step S405-control pattern selection)
In step S405, a generator (cut-off generator) assumed as a correction control target is selected. In addition, the image of selection of an interruption generator is the same as the concept shown in FIG. 13, for example. However, if the generator is shut off in the main control, the selection process of the shut-off generator is performed starting from an unselected interrupted generator.

(Step S406-Power Phase Difference Curve (After Control) Estimation)
In step S406, the state of the system after the generator is shut off is grasped, and the power phase difference angle curve is recalculated.

(Step S407-angular velocity deviation, phase angle correction)
In step S407, assuming the state after the generator is shut off, the values of angular velocity deviation and phase angle are recalculated.

(Step S408-energy value (V _A ', V _D ') calculation)
Based on the results of steps S406 and S407, the energy value after the generator is shut off is calculated.

(Step S409-Stability Determination (V _A '<V _D '))
In step S409, the magnitude relationship between the recalculated acceleration energy V _A ′ and deceleration energy V _D ′ is compared. If the deceleration energy V _D ′ is greater than the acceleration energy V _A ′ (step S409, Yes), step S410 is performed. Migrate to On the other hand, if the deceleration energy V _D ′ is equal to or less than the acceleration energy V _A ′ (step S409, No), the processing from step S405 is repeated.

(Step S410—Confirm control target)
In step S410, the currently selected blocking pattern is determined as a control target in the correction control, and the process flow of FIG. 14 is exited.

By the way, the description of steps S401 to S410 described above is based on Case 1 (in the case of inheriting the values of P and P ₁ obtained by the main control calculation) and Case 2 (P ₀ and P ₁ obtained by the main control calculation). This is a common explanation in the case of correction. On the other hand, in case 2, correction processing for P ₀ and P ₁ is added. Therefore, the correction processing of these P ₀ and P ₁ will be described below.

(P ₀ and P ₁ correction processing)
FIG. 16 is a diagram illustrating an example of coefficient setting values after correction of the power phase difference angle curve in the correction control calculation. In FIG. 16, the transition of the assumed accident is shown on the front side (left column) of the chart, and the table shows the coefficient set values after correction for the coefficients P ₀ and P _1. The suffix h attached to P ₀ and P ₁ means a value after correction.

Of these correction values, the coefficient P _0h is a correction value of the coefficient P _0, P _1h is the values of P _0, P ₁ calculated in the main control calculation based on the measurement values voltage correction (power phase angle curve Is corrected in the vertical axis direction).

The correction value of the coefficient P ₁ is corrected so that the power phase difference angle curve obtained by the main control calculation does not change in the horizontal direction and passes through the operating point after the accident is removed. It can be expressed as (23) to (31).

The meanings of the symbols in the above formula are as follows, as shown in FIG.
P _0h : Power phase difference angle curve coefficient P ₀ after voltage correction
P _11h : Power phase difference angle curve coefficient P ₁ (for correction control) from initial accident removal to reclosing (failure)
P _11hc1 : Power phase difference curve coefficient P ₁ from initial accident elimination to reclosing (failure) (for correction control, main control implementation state)
P _11hc2 : Power phase difference angle curve coefficient P ₁ from initial accident elimination to reclosing (failure) (for correction control, correction control execution state)
P _1hF : Power phase difference angle curve coefficient P ₁ from the reclosing failure time to the reclosing success time (at the time of final interruption)
P _12h : Power phase difference angle curve coefficient P ₁ after final interruption (for correction control)
P _12hc1 : Power phase difference angle curve coefficient P ₁ after final shutoff (for correction control, main control implementation state)
P _12hc2 : Power phase difference angle curve coefficient P ₁ after final interruption (for correction control, correction control execution state)
X _2c1 : Reactance X ₂ after main control
X _2c2 : Reactance X ₂ after execution of correction control

  According to the system stabilization control system of the embodiment described above, control by a pre-calculation method that performs stability determination and control amount calculation for each assumed case that is a presumed accident case before the occurrence of the accident, and after the accident In combination with post-computation control that performs stability determination and control amount calculation based on the measurement information, and constructed each control based on the equal area method, high speed and uncertainties that are advantages of the pre-computation method It is possible to effectively combine the flexibility, which is an advantage of the post-calculation method that can cope with unexpected events due to factors and the like, and it is possible to further improve the control speed and control accuracy.

(Modifications related to arithmetic processing)
In addition, about a part of control method shown above, various deformation | transformation (change) is possible. For example, as apparent from a comparison between FIG. 4 and FIG. 10, in calculating the acceleration energy V _A , the main control does not consider the generator output decrease at the time of the accident (considered in the correction control). . This is because the main control gives priority to high speed, so the calculation processing is as simple as possible. On the contrary, if a processor with higher arithmetic processing can be used, the generator output will decrease. Control accuracy is expected to be improved by taking this into consideration.

FIG. 17 is an image diagram for explaining a modification example (first technique) of the arithmetic processing. In the method shown in FIG. 17, the generator output reduction amount in the event of an accident (= P _M -P _F), the generator output decrease rate (= P _F / P _M) in advance anticipation is set and, the generator Based on the output decrease amount or the generator output decrease rate, the acceleration energy V _A is calculated in consideration of the area of the hatched portion in the figure. By taking into account such a decrease in generator output, an improvement in control accuracy in the main control calculation (preliminary calculation) can be expected. In addition, such consideration can reduce operability in terms of increasing settling items, but can be expected to reduce the possibility of insufficient control amount in the main control (pre-computation) portion.

FIG. 18 is an image diagram for explaining a modification example of the arithmetic processing (second method). In the power phase difference angle curve shown in FIG. 17, the horizontal axis represents the phase angle, but in the power phase difference angle curve shown in FIG. 18, the horizontal axis represents the time. In the first method shown in FIG. 17, the generator output (P _F ) that preliminarily anticipates the generator output decrease amount or the generator output decrease rate at the time of the accident is determined. The generator output decrease amount or the generator output decrease rate at the time of occurrence is calculated using measurement information at or near the time of the accident. This second method uses measurement information during an accident together, but uses a part (initial) information during an accident, and is logically more than control by a general post-operation method. Since it is a simple process, higher speed control can be expected compared to control by a general post-calculation method.

FIG. 19 is an image diagram for explaining a modification example (third method) of the arithmetic processing. In the second method shown in FIG. 18, the generator output (P _F ) is determined using measurement information at the time of occurrence of the accident or in the vicinity thereof. It not, is set to be calculated generator output (P _F) using measurement information from the event of an accident to the time the fault is cleared. This third method also uses measurement information during the accident, but it uses only a part of the information during the accident (very early information), and is a logically common post-operation. Since the processing is simpler than the control by the method, higher speed control can be expected compared to the control by the general post-calculation method. Further, compared to the second method, more measurement information can be used, so that the curve during the accident can be simulated with high accuracy, and the control accuracy can be improved while increasing the control speed.

  Note that the method described in the above embodiment is an example of the configuration of the present invention, and can be combined with another known technique, and a part thereof is omitted without departing from the gist of the present invention. Needless to say, it is possible to change the configuration.

  As described above, the present invention is useful as a system stabilization control system that enables further improvement in control speed and control accuracy.

2,20,21,23 Substation 3 (3a-3n), 25, 27 Power plant 4 Generator group 6, 20a, 20b, 21a, 25a, 27a Bus 7 Breaker 8 Current transformer 9 Instrument transformer 10 Central processing unit 15 (15a to 15n) Control terminal 18 (18a to 18n) Communication line 22, 28a to 28c Transmission line 29 (29a to 29c), 45 to 49 Step-up transformer 31 Infinite bus 32 Load bus 33 Equivalent generator output End 34 Equivalent generator virtual output end 40-44 Equivalent generator

Claims (6)

A system stabilization control system configured to be applicable to a power system including a plurality of power plants composed of a plurality of generators, and stabilizing the power system by performing a generator control according to an accident situation. ,
Control by pre-computation method that performs stability determination and control amount calculation for each accident case assumed in advance before the occurrence of the accident, and control by post-operation method that performs stability determination and control amount calculation based on measurement information after the accident And constructing each control based on the equal area method,
In the main control calculation by the pre-calculation method, the first curve that is the power phase difference angle curve before the accident, the second curve that is the power phase difference angle curve after the accident removal, and the power phase difference angle curve after the reclosing. The deceleration energy is calculated using the third curve,
In the correction control calculation by the posterior calculation method, deceleration energy is calculated using the first to third curves and a fourth curve that is a power phase difference angle curve during re-failure. System stabilization control system. In the main control calculation by the pre-calculation method, the control calculation is performed without considering the generator output decrease at the time of the accident,
2. The system stabilization control system according to claim 1, wherein in the correction control calculation by the post-calculation method, the control calculation is performed in consideration of a decrease in the generator output at the time of an accident.   In the main control calculation by the prior calculation method, the generator output decrease amount or the generator output decrease rate at the time of the accident is calculated in advance, and the calculated generator output decrease amount or the generator output decrease rate is taken into consideration. The system stabilization control system according to claim 1, wherein acceleration energy is calculated.   In the main control calculation by the pre-calculation method, the generator output decrease amount or the generator output decrease rate at the time of the accident is calculated using measurement information at or near the time of the accident, and the calculated generator output decrease The system stabilization control system according to claim 1, wherein the acceleration energy is calculated in consideration of an amount or a generator output reduction rate.   In the main control calculation by the prior calculation method, the generator output decrease amount or the generator output decrease rate at the time of the accident is calculated using measurement information from the time of the accident to the time of accident removal, and the calculated generator output The system stabilization control system according to claim 1, wherein acceleration energy is calculated in consideration of a decrease amount or a generator output decrease rate.   In the correction control calculation by the post-calculation method, the coefficient value of the power phase difference angle curve used in the control calculation by the pre-calculation method is corrected using the measurement information after the occurrence of the accident, and the corrected coefficient value is obtained. The system stabilization control system according to claim 1, wherein stability determination and control amount calculation are performed using a power phase difference angle curve based thereon.

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