JP7434113B2 - Grid stabilization device, grid stabilization method, and program - Google Patents

Description

Embodiments of the present invention relate to a system stabilizing device, a system stabilizing method, and a program.

In order to prepare for the occurrence of an accident in the power system, a system stabilization device aimed at stabilizing the power system periodically calculates transient stability in the event of an accident based on the power state before the accident. There is a method in which generators (hereinafter also referred to as power shedding generators) are targeted for disconnection (hereinafter also referred to as shutoff or power shedding) in response to an accident (for example, Patent Document 1).

In the above-mentioned system stabilization device, the transient stability calculation of a system model that reflects power system information at a cycle of 1 minute, etc. is used to select the power control equipment necessary to prevent step-out in the event of a system fault. If the state of the power system changes due to a sudden change in the output of a renewable energy power source during the stability calculation period, there is a possibility that the power cutter required to prevent step-out may not be available, and it may not be possible to prevent step-out.

“Appendix 2 Example of a relay system to prevent synchronization”, October 2000, Technical Report of the Institute of Electrical Engineers of Japan, No. 801, p. 153-154

The problem to be solved by the present invention is to prevent step-out by correcting the amount of power control necessary to prevent step-out in the event of a grid fault, even when the state of the power system changes due to sudden changes in the output of renewable energy power sources. It is an object of the present invention to provide a system stabilization device, a system stabilization method, and a program that can prevent such occurrences.

The system stabilization device of the embodiment collects system information including at least active and reactive power of power transmission lines that constitute the power system, constructs a system model, and performs transient stability calculations under assumed accident conditions in advance. In order to prevent generator out-of-step for each assumed accident condition, a first electrically controlled generator is selected in advance, and when a system fault occurs, the first electrically controlled generator that has been selected in advance is Prevents step-out by disconnecting the generator. The grid stabilization device has a stability evaluation model generation section and an additional power control execution section. The stability evaluation model generation unit generates, before an accident occurs, model definition information for estimating a future value of phase angle deviation used to determine whether or not one or more generators included in the power system step out; The determination reference value used to determine whether or not the generator is out of step is prepared based on the result of the immediately preceding transient stability calculation. After the occurrence of an accident, the additional power control execution unit adjusts the discrimination reference value prepared by the stability evaluation model generation unit based on the measured values of the power system, and measures the power system before and after the accident. When it is determined that the generator included in the power system will step out of synchronization based on the future value of the phase angle deviation predicted by applying the value to the model definition information and the adjusted determination reference value. Select an additional electric power generator.

FIG. 1 is a block diagram showing the configuration of a power supply system to which a system stabilizing device 20 of the present embodiment is applied. 5 is a flowchart illustrating an example of the flow of processing performed by the additional electricity restriction execution unit 50 of the present embodiment. FIG. 5 is a diagram illustrating processing performed by the additional electricity restriction execution unit 50 of the present embodiment.

Hereinafter, a system stabilizing device, a system stabilizing method, and a program according to embodiments will be described with reference to the drawings. In the following description, multiple components of the same type are distinguished by adding a numerical value such as "1" or "2" to the end of the code via a "-" (hyphen). When a plurality of configurations of the same type are not distinguished from each other, adding a numerical value such as "1" or "2" to the end of the code via a "-" (hyphen) is omitted.

FIG. 1 is a block diagram showing the configuration of a power supply system to which a system stabilizing device 20 of this embodiment is applied. The power supply system includes, for example, a power system 1, a transmission system 10, and a system stabilization device 20.

The power system 1 includes busbars 2 (busbars 2-1 to 2-5), transmission lines 3 (transmission lines 3-1 to 3-4), and transformers 4 (transformers 4-1 to 4-4). , the generator 5 (generators 5-1 to 5-4), the circuit breaker 6 (circuit breaker 6-1 to 6-4), the information terminal 11 (information terminal 11-1 to 11-5), and the control and terminals 12 (control terminals 12-1 and 12-2).

The transformer 4 transforms the voltage of the power generated by the generator 5 to a predetermined voltage. For example, the transformer 4-1 transforms the voltage of the power generated by the generator 5-1 to a predetermined voltage. The generator 5 is a device that generates electric power using renewable energy such as solar power or wind power, or exhaustible energy such as fossil fuel such as a synchronous machine such as a thermal power plant, a nuclear power plant, or a hydraulic power plant. The circuit breaker 6 interrupts the supply of electric power generated by the generator 5 to consumers. For example, the circuit breaker 6-1 cuts off the supply of power generated by the generator 5-1. The transmission system 10 is constituted by a communication network such as a dedicated communication line or the Internet, and transmits various information such as system information, which will be described later, between the information terminal 11 and the system stabilization device 20.

The information terminal 11 measures information (hereinafter referred to as system information) regarding the electric power supplied from the generator 5 to the consumer via the bus 2.

The system information includes power information regarding the supply and demand status of power in each component of the power system 1 (bus 2, power transmission line 3, transformer 4, generator 5, circuit breaker 6, information terminal 11, and control terminal 12), and Contains connection information regarding the connection status of The electrical information included in the system information includes the active power and reactive power of the power transmission line 3 and the transformer 4, the bus voltage applied to the bus 2, and the like. Further, the connection information included in the system information includes the connection state between the power transmission line 3 and the transformer 4, and the like. The system information includes, for example, information such as the voltage and phase angle of each bus 2 in the power system 1, active power flow and reactive power flow of the power transmission line 3, starting/stopping information of the generator 5, and the like. For example, the information terminal 11-1 may provide power information related to the power supplied by the power transmission lines 3-1, 3-2, 3-5 connected to the bus 2-1, and connection information of the power transmission line 3-1, etc. Measure the lineage information included.

The control terminal 12 controls the circuit breaker 6 in accordance with the control signal from the system stabilizing device 20, and controls the cutoff of the power supply from the generator 5. For example, the control terminal 12-1 controls the circuit breakers 6-1 and 6-2 in response to a control signal from the system stabilizing device 20, and controls the interruption of the power supply via the bus 2-4. .

In the power system 1, the range to the left from the power transmission line 3-5 from which system information cannot be obtained is referred to as an external system, and the range to the right from the power transmission line 3-5 from which system information can be obtained is referred to as an internal system. Further, the interconnection point, which will be described later, means the bus line 2-1 that is the boundary between the range where grid information can be obtained and the range where it cannot be obtained, and the interconnection line means the power transmission line 3-5. Note that the external system also includes a plurality of busbars 2, power transmission lines 3, transformers 4, generators 5, and the like.

The system stabilization device 20 acquires system information via the transmission system 10, performs transient stability calculations based on the acquired system information, and maintains the stability of the power system 1 in the event of a hypothetical accident. Select the power control machine that performs power control. Here, the power cutter is a generator 5 that cuts off the supply of electric power. In the following explanation, "accident" means a system accident.

In this embodiment, in addition to the above-described transient stability calculation, the system stabilization device 20 performs additional power control when the state of the power system 1 changes in a cycle shorter than the cycle in which the transient stability calculation is performed. It is determined whether or not additional power restriction is necessary, and if additional power restriction is necessary, a power restriction device to perform additional power restriction is selected.

The system stabilization device 20 includes a power restriction execution unit 30, a stability evaluation model generation unit 40, and an additional power restriction execution unit 50. The power restriction execution unit 30 is a functional unit that performs processing related to power restriction using conventional transient stability calculation. The stability evaluation model generation unit 40 and the additional power restriction execution unit 50 are functional units that perform processing related to additional power restriction.

The power control execution section 30 includes a system information collection section 31, a basic system storage section 32, a system model creation section 33, a stability calculation section 34, a power control machine selection section 35, and a first stage power control section 36. and a calculation result storage section 37.

The system information collection unit 31 acquires system information from the information terminal 11 via the transmission system 10 at preset intervals (for example, 1 minute). The system information collection unit 31 outputs the acquired system information to the system model creation unit 33.

The system model creation unit 33 creates a simulation model (hereinafter referred to as a system model) representing the power flow state of power in the power system 1 based on the system information acquired by the information terminal 11 and the configuration information stored in the basic system storage unit 32. ). The basic system storage unit 32 stores configuration information.

The configuration information is information regarding the configuration of each component of the power system 1. The configuration information is, for example, information indicating the impedance and inductance of the power transmission line 3 included in the power system 1, interconnection information between the bus bar 2 and the power transmission line 3, the scale, number, arrangement, etc. of each component of the power system 1.

The stability calculation unit 34 performs a system analysis simulation by transient stability calculation using the system model. The stability calculation unit 34 executes transient stability calculations when various preset assumed accidents occur, and determines whether the generator will not step out or will step out, that is, whether the power system is stable or unstable. Determine whether The stability calculation unit 34 outputs the determination result to the power cut machine selection unit 35. If the determination result by the stability calculation unit 34 is unstable, the power shedding machine selection unit 35 selects and adds one of the generators that step out as a power shedding machine. The stability calculation unit 34 executes transient stability calculation under the conditions for cutting off the electricity shedding machine selected by the electricity shedding machine selection unit 35, again determines whether it is stable or unstable, and applies the determination result to the electricity shedding machine. It is output to the selection section 35. By repeating this exchange between the stability calculation unit 34 and the power shedding machine selection unit 35 until the determination result becomes stable, the power shedding machine that can maintain the stability of the power system in a hypothetical accident is determined (selected). Ru. Note that a series of processes for determining the first electrically-controlled generator, which was carried out immediately before the occurrence of a ground fault or the like, is referred to as a last-minute calculation.

The electricity control unit selection unit 35 outputs information on the electricity control unit selected to stabilize the power system 1 when a hypothetical accident occurs to the first stage electricity control unit 36. Further, the stability calculation unit 34 causes the calculation result storage unit 37 to store various conditions and calculation results including the system model used for the transient stability calculation and the selection result of the electrical cutoff machine.

The first-stage electrical control section 36 detects the occurrence of an accident and the accident conditions in the power system 1 via the transmission system 10, and shuts off the control terminal 12 of the electrical control machine selected in advance in a hypothetical accident corresponding to the accident condition. Send commands. Thereby, the corresponding generator 5 is disconnected from the power system 1. The calculation result storage unit 37 stores calculation results and various conditions including the system model used in the transient stability calculation and the selection results of the electrical control equipment.

The stability evaluation model generation unit 40 includes an unstable system model formulation unit 41 , a stable system model formulation unit 42 , a discrimination criterion formulation unit 43 , and an output change model formulation unit 44 .

The unstable side system model formulation unit 41 calculates various constants for calculating the state quantities of the unstable generator group model under the accident conditions of each assumed accident. The unstable generator group model is a model in which a plurality of generators 5 (unstable generator group) belonging to the unstable side system are combined into one generator equivalent to the plurality of generators. The generators 5 belonging to the unstable system are the generators 5 that do not maintain stability when a hypothetical accident occurs, that is, the generators 5 that can become unstable, and are the generators 5 that are subject to electrical blackout in the hypothetical accident. .

For example, the unstable side system model formulation unit 41 examines (calculates) the internal voltage phase angle difference of each generator 5 based on the phase angle gravity center of all the generators 5, and determines whether the calculated phase angle difference is a predetermined value. The generator exceeding the designated value is defined as generator 5 belonging to the unstable system.

In addition, as shown in (Equation 1), the unstable side system model formulation unit 41 uses an inertia constant M ₁ of the unstable generator group model as various constants for calculating the state quantities of the unstable generator group model. Calculate.

In (Formula 1), M _i represents the inertia constant of the generator 5 with identification number i belonging to the unstable system. The identification number i (i=0 to n) is a number that uniquely identifies an unstable generator (generator 5 belonging to the unstable system). n is any natural number.

The stable side system model formulation unit 42 uses the calculation results stored in the calculation result storage unit 37 to construct in advance a function for estimating the total active power of the generators included in the external system under each accident condition. put. Furthermore, the stable system model formulation unit 42 calculates various constants for calculating the state quantities of the stable generator group model under the accident conditions of each assumed accident.

The stable generator group model is a model in which a plurality of generators 5 belonging to a stable system (stable generator group) are combined into one generator equivalent to the plurality of generators 5. A stable system is a system that is estimated to maintain stability in the face of a hypothetical accident, and is, for example, a collection of generators located far away from the point where the hypothetical accident occurs from the viewpoint of electrical connections. be. This is because the generator 5 installed at a location away from the location where the hypothetical accident is expected to occur is less likely to be affected by the hypothetical accident and is considered to maintain stability against the hypothetical accident.

For example, the stable side system model formulation unit 42 examines (calculates) the internal voltage phase angle difference of each generator based on the phase angle gravity center of all the generators 5, and sets the calculated phase angle difference to a predetermined designated value. The generators 5 that do not exceed the above are defined as generators 5 belonging to the stable system.

Here, it is considered that the stable system is often installed at a location far from the location where the assumed accident occurred, so it is not possible to directly measure system information on the stable system using the information terminal 11. It can be assumed that this is the case in most cases. For this reason, it is difficult to measure system information of the stable system in real time immediately after an accident actually occurs.

As a countermeasure for this, in the present embodiment, the stable system model formulation unit 42 shows the relationship between the total load of the stable system and the interconnection point bus voltage as a function for estimating the active power of the stable generator group model. Create a regression model (function). As a result, the system information of the stable system immediately after the accident is estimated using a regression model.

In addition, the stable side system model formulation unit 42 calculates the inertia constant _M2 of the stable generator group model as various constants for calculating the state quantities of the stable generator group model, as shown in (Equation 2). .

In (Formula 2), _M2 represents the inertia constant of the stable generator group model, and _Mj represents the inertia constant of the generator 5 with identification number j belonging to the stable system. The identification number j (j=0 to m) is a number that uniquely identifies a stable generator (generator 5 belonging to the stable system). m is any natural number.

The discrimination criterion formulation unit 43 calculates, for example, a threshold value (hereinafter, discrimination reference value R) of the phase angle deviation Δδ of the integrated generator model. The phase angle deviation will be explained in detail later. The integrated generator model discrimination reference value R is used as a threshold value for determining the degree of stability of the integrated generator model after the occurrence of an accident by the stability determining unit 73 of the additional power reduction execution unit 50, which will be described later.

The relationship between the active power deviation _ΔPG (described later) and Δδ of the integrated generator model obtained from the unstable transient stability calculation result one step before the first number of electrically controlled generators becomes stable is as follows up to a certain Δδ. follows a trajectory that can be approximated by a sine function in which _ΔPG increases and then begins to decrease. The discrimination criterion formulation unit 43 sets Δδ when _ΔPG starts to decrease and becomes 0 as the discrimination criterion value R. A discrimination reference value R is prepared for each accident condition. Further, the discrimination criterion formulation unit 43 stores Δδ when _ΔPG is maximum.

The output change model formulation unit 44 uses the calculation results stored in the calculation result storage unit 37 to determine the amount of change in the active power deviation ΔP _G of the integrated generator model due to the implementation of the first power shedding and additional power shedding. Calculate the coefficients in advance to find the value. The amount of change in the active power deviation _ΔPG referred to here is a stepwise amount of change immediately after the power reduction is implemented. The output change model formulation unit 44 further calculates other unstable conditions as seen from the terminal busbar of the additional shelved generator in the full shelving pattern in which each additional shelved generator candidate is added to the first shelved generator. Find the short-circuit impedance to the generator and the short-circuit impedance to the stable generator, and calculate the ratio with the sum of the two short-circuit impedances as the denominator and the short-circuit impedance to the stable generator as the numerator. As described above, the model information formulated by the unstable side system model formulation unit 41, the stable side system model formulation unit 42, and the output change model formulation unit 44 is an example of "model definition information."

The additional electricity restriction execution unit 50 is a functional unit that operates after an accident occurs in the power system. The additional power shedding execution unit 50 generates, by the stability evaluation model generation unit 40, whether or not to perform additional power shedding after the first power shedding machine has executed the power shedding when an accident occurs in the power system. If additional electricity control is required, the target electricity reduction machine is selected.

The additional power shedding execution unit 50 includes a high-speed information collection unit 51, a generator status calculation unit 60, an output change estimation unit 71, a discrimination criterion adjustment unit 72, a stability determination unit 73, and an additional power shedding selection unit. 74.

The high-speed information collection unit 51 acquires system information via the transmission system 10 at a sampling cycle (for example, on the order of milliseconds) that is faster than the cycle at which the power control execution unit 30 acquires system information. The grid information here includes various information such as generator active power, transmission line active power, phase angle difference between interconnection point and each generator, interconnection point voltage, interconnection line active power, etc. . The high-speed information collection unit 51 always collects system information at a high-speed sampling period, writes it into a buffer memory, and retains system information for a certain time interval so that it can be referenced. When the high-speed information collection unit 51 determines that an accident has occurred, the high-speed information collection unit 51 operates from a predetermined time before the accident (hereinafter referred to as information collection start time) until a predetermined time has elapsed (hereinafter referred to as information collection end time). The system information collected during a certain time interval is extracted. The high-speed information collection unit 51 outputs the extracted system information for a certain time period to the generator state calculation unit 60.

Note that whether or not an accident has occurred can be determined by acquiring the operation signal of the protection relay. For example, one of the protection relays measures currents at both ends of a power transmission line, and determines whether the difference is greater than or equal to a predetermined threshold. In this case, if the difference in current is greater than or equal to a predetermined threshold, it is determined that an accident has occurred.

The generator status calculation unit 60 uses the system information acquired from the high-speed information collection unit 51 to calculate the status of the generator 5 after the accident occurs. The state of the generator 5 is, for example, an active power deviation ΔP _G and a phase angle deviation Δδ of the generator 5. The active power deviation _ΔPG is a time-series change in active power from the start of information collection to the end of information collection, based on the active power before the occurrence of the accident. The phase angle deviation Δδ is a time-series change in the phase angle from the start of information collection to the end of information collection, with the phase angle before the accident occurring as a reference.

The phase angle deviation Δδ of the integrated generator model is obtained by (Equation 3).

In (Equation 3), t is a predetermined time that has passed since the start of information collection, Δδ ₁ is the phase angle deviation of the unstable generator group model, and Δδ ₂ is the phase angle deviation of the stable generator group model.

Further, the phase angle deviation Δδ ₁ of the unstable generator group model is obtained based on (Equation 4) and (Equation 5).

In (Equation 4), δ ₁ indicates the phase angle of the unstable generator group model. In (Equation 5), M _i represents the inertia constant of the generator 5 with the identification number i belonging to the unstable system, and δ _i represents the phase angle of the generator 5 with the identification number i belonging to the unstable system.

Similarly, the phase angle deviation Δδ ₂ of the stable generator group model is obtained based on (Equation 6) and (Equation 7).

In (Equation 6), δ ₂ indicates the phase angle of the stable generator group model. In (Equation 7), M _j represents the inertia constant of the generator 5 with the identification number j belonging to the stable system, and δ _j represents the phase angle of the generator 5 with the identification number j belonging to the stable system.

The generator state calculation unit 60 includes an unstable generator calculation unit 61, a stable generator calculation unit 62, a phase angle deviation calculation unit 63, a phase angle deviation coefficient calculation unit 64, and an adjustment necessity determination unit 65. and a phase angle deviation estimator 66.

The unstable generator calculation unit 61 calculates a predetermined interval in a measurement period from the occurrence of an accident to the end of information collection based on various constants calculated by the unstable side system model formulation unit 41 and information collected by the high-speed information collection unit 51. Calculate the active power deviation ΔP _G1 of the unstable generator group model in steps (for example, 10 millisecond intervals). The predetermined interval depends on the cycle at which the high-speed information collection unit 51 collects information.

Specifically, the unstable generator calculation unit 61 subtracts the active power of the unstable generator group model before the occurrence of the accident from the active power of the unstable generator group model at time t, as shown in (Equation 8). By this, the active power deviation of the unstable generator group model is calculated.

In (Equation 8), ΔP _G1 is the active power deviation of the unstable generator group model, P _G1 (t) is the active power of the unstable generator group model at the time when a predetermined time t has passed from the start of information collection, P _G1 (0) indicates the active power of the unstable generator group model at the start of information collection (that is, before the accident occurs).

Note that the unstable generator calculation unit 61 calculates the active power P _G1 (t) at time t of the unstable generator group model using the unstable power collected by the high-speed information collection unit 51, as shown in (Equation 9). It is calculated by adding the active power P _Gi (t) of the generator 5 belonging to the side system at time t.

The stable generator calculation unit 62 calculates the calculation period for the measurement period from the occurrence of an accident to the end of information collection based on the functions and various constants obtained by the stable side system model formulation unit 42 and the information collected by the high-speed information collection unit 51. Calculate the active power deviation ΔP _G2 of the stable generator group model at predetermined intervals (for example, 10 millisecond intervals). As in the case of the unstable generator calculation section 61, this interval depends on the cycle at which the high-speed information collection section 51 collects information.

Specifically, the stable generator calculation unit 62 calculates the stability by subtracting the active power of the stable generator group model before the occurrence of the accident from the active power of the stable generator group model at time t, as shown in (Equation 10). Calculate the active power deviation of the generator group model.

In (Equation 10), ΔP _G2 is the active power deviation of the stable generator group model, P _G2 (t) is the active power of the stable generator group model at the time when a predetermined time t has passed from the start of information collection, P _G2 (0) indicates the active power of the stable generator group model at the start of information collection (that is, before the accident occurs).

The active power P _G2 (t) of the stable generator group model is defined as the sum of the active powers P _Gi (t) of the generators 5 belonging to the stable system at time t, as shown in (Equation 11).

In the actual calculation, the stable generator calculation section 62 inputs the interconnection point bus voltage collected by the high-speed information collection section 51 into the regression model constructed by the stable side system model formulation section 42. , the total load in the stable system may be estimated, and the difference between the measured active power flowing to the stable system and the estimated total load may be taken as the sum of the generator active power in the stable system. Then, the stable generator calculation unit 62 adds the measured value of the active power of the stable generators in the internal system to the sum of the active power of the generators in the stable side system, and sets it as the active power _PG2 of the stable generator group model.

The phase angle deviation calculation unit 63 calculates the active power deviation ΔP _G1 of the unstable generator group model calculated by the unstable generator calculation unit 61 and the effective power deviation ΔP G1 of the stable generator group model calculated by the stable generator calculation unit 62. Using the power deviation ΔP _G2 and (Equation 12), the phase angle deviation Δδ of the integrated generator model during the measurement period from the occurrence of the accident to the end of information collection by the high-speed information collection unit 51 is calculated.

In (Equation 12), M represents the inertia constant of the generator, and _ΔPG represents the active power deviation of the integrated generator model. The inertia constant M is calculated by (Equation 13) using the inertia constant M ₁ of the unstable generator group model and the inertia constant M ₂ of the unstable generator group model.

In addition, the active power deviation _ΔPG of the integrated generator model is determined by the inertia constant M ₁ of the unstable generator group model, the inertia constant M ₂ of the unstable generator group model, and the active power deviation _ΔPG of the unstable generator group model. , and the active power deviation ΔP _G2 of the stable generator group model, it is calculated by (Equation 14).

Note that (Formula 12) is the equation of motion shown in (Formula 15), in which the damping coefficient D is 0 and the mechanical input P _m is the active power P _G (0) before the accident occurs.

The phase angle deviation coefficient calculating section 64 calculates the phase angle deviation Δδ of the integrated generator model during the measurement period obtained by the phase angle deviation calculating section 63 and the active power deviation _ΔPG of the integrated generator model used for the calculation. , the coefficient K _S of (Equation 16) representing the relationship between the active power deviation _ΔPG and the phase angle deviation Δδ is calculated. The coefficient K _S is an example of a "first coefficient."

In (Formula 16), α is the difference between the phase angle deviation Δδ and π/2 [rad] at which the active power deviation _ΔPG is maximum, and is determined in advance by the discrimination criterion formulation unit 43. α is an example of a “second coefficient”.

The adjustment necessity determination unit 65 determines whether adjustment of the difference α in equation (16) is necessary based on the information collected by the high-speed information collection unit 51. When it is determined that adjustment is necessary, a preset value is subtracted from α, and the result is set as a new α. The difference α is determined to require adjustment when Y in (Equation 17) is less than or equal to a predetermined threshold value.

In (Equation 17), _YB represents an evaluation index of external system reactance corresponding to the immediately preceding calculation, and _YA represents an evaluation index of external system reactance based on measured values before and after the occurrence of an accident. Y _B is calculated by (Equation 18), and Y _A is calculated by (Equation 19).

Furthermore, X _B (t) in (Formula 18) is calculated by (Formula 20), and X _B (0) is calculated by (Formula 21). Moreover, X _A (t) in (Formula 19) is calculated by (Formula 22), and X _A (0) is calculated by (Formula 23).

In (Formula 20) to (Formula 23), δ(0) is the initial phase angle value converted to the integrated generator model obtained from the previous calculation result, Δδ is the phase angle deviation converted to the integrated generator model, and P is the interconnection line. , and V indicates the bus voltage at the interconnection point. Further, the subscript B represents the result of the previous calculation and the calculated value using the result, and A represents the measured value and the calculated value using the measured value.

The phase angle deviation estimating unit 66 starts from the active power deviation ΔP _G of the integrated generator model immediately after the first power shedding, which reflects the influence of the first power shedding calculated by the output change estimating unit 71, which will be described later. , the phase angle deviation Δδ (future value) of the integrated generator model at each time step after the first power outage is determined by time-series iterative calculation using the above-mentioned (Equation 12) and (Equation 16). However, the inertia constant M in (Equation 12) is a value obtained by subtracting the amount for the generator selected in the first power control. Furthermore, if additional electricity curtailment is implemented after the first electricity curtailment, the phase angle deviation estimation unit 66 adds the change in the active power deviation ΔP _G of the integrated generator model obtained by the output change estimation unit 71. By adding to the active power deviation _ΔPG of the integrated generator model at the time of power cut, and by repeating the time series calculation using the above-mentioned (Equation 12) and (Equation 16), the phase of the integrated generator model after the additional power cut is calculated. Find the angular deviation Δδ. In this case, the inertia constant M in (Equation 12) is a value obtained by subtracting the amount for the generator selected in the first power restriction and the additional power restriction.

The output change estimating unit 71 calculates the change in the active power deviation ΔP _G of the integrated generator model at the time of implementing the first power outage, which has been calculated in advance by the output change model formulating unit 44, from the integrated generator immediately before the power outage. Add to model active power deviation _ΔPG . The output change estimating unit 71 also multiplies the short-circuit impedance ratio obtained from the output change model formulating unit 44 by the active power before the accident of the additional power shedding machine selected by the additional power shedding machine selection unit 74, which will be described later. , the change in the active power deviation _ΔPG of the integrated generator model is determined.

The discrimination criterion adjustment section 72 adjusts the discrimination criterion value R obtained by the discrimination criterion formulation section 43 as necessary. First, the discrimination standard adjustment unit 72 acquires the measured value of the phase angle difference between the interconnection point and each unstable generator before the occurrence of the accident from the high-speed information collection unit 51, and obtains the measured value of the phase angle difference between the interconnection point and each unstable generator in the immediately preceding calculation. The phase angle difference between the stable generators is acquired from the calculation result storage unit 37. Next, for each generator, the difference between the phase angle difference of the measured value and the phase angle difference of the immediately preceding calculation is taken, and one phase angle difference is determined by inertia weighted averaging. Then, when this phase angle difference is a positive value, that is, when the phase angle difference of the measured value is larger than the previous calculation, the discrimination value obtained by the discrimination criterion formulation unit 43 is determined by using the double value of the phase angle difference obtained by the inertia weighted average. The value R is subtracted from the reference value R to obtain a new discrimination reference value R. As a result, when the phase angle difference between the measured values is larger than the previous calculation, the discrimination reference value R becomes smaller, so that it becomes easier to discriminate that something is unstable, and it is less likely that something unstable will be incorrectly judged as stable.

The stability determination unit 73 compares the phase angle deviation Δδ of the integrated generator model estimated by the phase angle deviation estimation unit 66 with the discrimination reference value R obtained from the discrimination reference adjustment unit 72. The stability determination unit 73 determines that the phase angle deviation Δδ is stable when the maximum value is less than the determination reference value R, and is unstable when the maximum value of the phase angle deviation Δδ is less than the determination reference value R. It is determined that

Based on the coefficients obtained by the output change model formulation unit 44, the additional power shedding machine selection unit 74 selects, from among the additional power shedding candidates, the change in active power deviation ΔP _G of the integrated generator model due to power shedding is the largest. Select the item as an additional electricity control machine. The additional power shedding machine selection unit 74 selects, as the additional power shedding machine, the one having the largest short-circuit impedance ratio obtained from the output change model formulation unit 44 . The additional power shedding machine selection unit 74 may determine the stability of all combinations of additional power shedding candidates, and select the additional power shedding machine that provides the minimum amount of power shedding from among the stable combinations.

FIG. 2 is a flowchart illustrating the flow of processing performed by the additional electricity restriction execution unit 50 of this embodiment. First, the high-speed information collection unit 51 collects system information in a specified fixed time interval from among system information collected in advance at a high-speed sampling period (step S1).

Next, the unstable generator calculation unit 61 calculates the measurement period from the occurrence of the accident to the end of information collection based on the various constants calculated by the unstable side system model formulation unit 41 and the information collected by the high-speed information collection unit 51. Calculate the active power deviation ΔP _G1 of the unstable generator group model at (step S2). Next, the stable generator calculation unit 62 calculates the stable generator group for the measurement period based on the function and various constants obtained by the stable side system model formulation unit 42 and the information collected by the high-speed information collection unit 51. The active power deviation ΔP _G2 of the model is estimated (step S3).

Next, the phase angle deviation calculation unit 63 calculates the active power deviation ΔP _G1 of the unstable generator group model calculated by the unstable generator calculation unit 61 and the stable generator group calculated by the stable generator calculation unit 62. The phase angle deviation Δδ of the integrated generator model during the measurement period is calculated based on the active power deviation _ΔPG2 of the model (step S4). Next, the phase angle deviation coefficient calculation unit 64 calculates the phase angle deviation Δδ of the integrated generator model during the measurement period calculated by the phase angle deviation calculation unit 63 and the active power deviation ΔP of the integrated generator model used for the calculation _. Based on this, an active power deviation estimation coefficient K _S is calculated (step S5).

Next, the adjustment necessity determining unit 65 determines whether adjustment of the estimation coefficient is necessary based on whether Y in (Equation 17) is less than or equal to a predetermined threshold (step S6). The adjustment necessity determining unit 65 determines that adjustment is necessary when Y is less than or equal to a predetermined threshold, and, for example, subtracts a preset value from α and sets the result as a new α. do.

Next, the output change estimating unit 71 calculates the change in the active power deviation ΔP _{G of the integrated generator model at the time of implementing the first power outage, which has been calculated in advance by the output change model formulating unit 44, and calculates the change in the active power deviation ΔP G} of the integrated generator model at the time of implementing the first power outage. It is added to the active power deviation _ΔPG of the integrated generator model (step S7). Next, the phase angle deviation estimating unit 66 sets the active power deviation ΔP _G of the integrated generator model immediately after the first power shedding, which reflects the influence of the first power shedding calculated by the output change estimating unit 71, as a starting point. Then, the phase angle deviation Δδ of the integrated generator model at each time step after the first power outage is determined by time series iterative calculation using the above-mentioned (Equation 12) and (Equation 16) (Step S8).

Next, the discrimination standard adjustment unit 72 determines whether the phase angle difference obtained by the one inertia weighted average described above is a positive value, and if it is a positive value, determines the double value of the phase angle difference. The value is subtracted from the discrimination reference value R obtained by the criterion formulation unit 43 to obtain a new discrimination reference value R (step S9). Next, the stability determining unit 73 compares the phase angle deviation Δδ of the integrated generator model estimated by the phase angle deviation estimating unit 66 and the discrimination reference value R obtained from the discrimination criterion adjusting unit 72. The stability determination unit 73 determines that the phase angle deviation Δδ is stable when the maximum value is less than the determination reference value R, and is unstable when the maximum value of the phase angle deviation Δδ exceeds the determination reference value R. (Step S10).

When the stability determination unit 73 determines that the power is unstable, the additional power shedding machine selection unit 74 selects an integrated generator by power shedding from among the additional power shedding candidates based on the coefficients determined by the output change model formulation unit 44. The model with the largest change in active power deviation _ΔPG is selected as the additional power cutter (step S11). Next, the output change estimating unit 71 multiplies the short-circuit impedance ratio obtained from the output change model formulating unit 44 by the pre-fault active power of the additional shedding machine selected in step S10 to calculate the active power of the integrated generator model. The deviation ΔPG is defined as the change in _G (step S12).

Next, the phase angle deviation estimation unit 66 converts the change in the active power deviation _ΔPG of the integrated generator model obtained by the output change estimation unit 71 into the active power deviation _ΔPG of the integrated generator model at the additional power cut time. Then, the phase angle deviation Δδ of the integrated generator model after the additional power cut is calculated by repeating time-series calculation using the above-mentioned (Equation 12) and (Equation 16) (Step S13). Thereafter, the phase angle deviation estimation unit 66 returns the process to step S10.

If the stability determining unit 73 determines that the generator is stable, the additional power shedding execution unit 50 transmits a cutoff command to the control terminal 12 of the additional power shedding machine selected by repeating steps S11 to S13, and the corresponding generator is disconnected from the power system (step S14). If the processing from step S11 to step S13 is not executed and the processing proceeds to step S14, no additional electricity control machine is selected. Therefore, the additional electricity restriction execution unit 50 does not send a shutdown command to the control terminal 12 of any generator.

FIG. 3 is a diagram illustrating the processing performed by the additional electricity restriction execution unit 50 of this embodiment. Figure 3 shows the time-series changes in the active power deviation and phase angle deviation of the generator 5, where time t0 is the time when information collection starts (before the accident), time t1 is the time when the accident occurs (accident occurrence), and time t2 is the time when the accident occurs. At the time of removal (accident removal), time t3 is the time when information collection is completed (measurement is completed), time t4 is when power reduction is executed by the first power reduction machine (first power reduction), and time t5 is when additional power reduction is executed ( (additional electric power system) is shown.

The top diagram in FIG. 3 shows the transition of the active power deviation _ΔPG2 of the stable generator group model. At time t1 when the accident occurred, ΔP _G2 decreased, but after time t2 when the accident was eliminated, ΔP _G2 increases. The second diagram from the top of FIG. 3 shows the transition of the active power deviation ΔP _G1 of the unstable generator group model. At time t1, ΔP _G1 decreased significantly, and after t2, although it increased slightly, it started to decrease again. The third row from the top of FIG. 3 shows the active power deviation ΔP _G of the integrated generator model obtained from ΔP _G2 and ΔP _G1 (Equation 14). Similar to ΔP _G1 , ΔP _G also decreased significantly at time t1, and after time t2, although it increased slightly, it started to decrease again. The fourth row from the top of Figure 3 shows the transition of the phase angle deviation Δδ of the integrated generator model, which is obtained by subtracting the phase angle deviation Δδ ₂ of the stable generator group model from the phase angle deviation Δδ ₁ of the unstable generator group model. ing. After time t1, the phase angle deviation Δδ increases monotonically.

The above description is about the transition before time t3 when the measurement ends, but the transition after time t3 is expected to change depending on the presence or absence of electrical restrictions. Specifically, the active power deviation and phase angle are calculated for (A) no electrical shedding, (B) only the first electrical shedding, and (C) additional electrical shedding. Explain the prediction of deviation trends.

(A) When electrical control is not implemented, after time t3, the phase angle deviation Δδ exceeds the discrimination reference value R and increases monotonically, and accordingly, the active power deviation _ΔPG deviates from zero and monotonically decreases. Unfavorable because it is predictable. (B) When only the first electrical control is performed, it is predicted that the slope of increase in the phase angle deviation Δδ decreases at time t4, and the active power deviation _ΔPG takes a positive value. However, it is still predicted that the phase angle deviation Δδ will monotonically increase beyond the discrimination reference value R, and accordingly, the active power deviation _ΔPG will deviate from zero and monotonically decrease, which is not preferable. (C) When implementing additional electricity shedding, it is predicted that the phase angle deviation Δδ will start to decrease at time t5, and the active power deviation _ΔPG will remain positive and not deviate from zero after time t5. ,preferable.

According to at least one embodiment described above, functions and coefficients prepared in advance based on the calculation results of the transient stability calculation and measurement information of the power system and generator before and after the occurrence of the accident are used to calculate the After calculating the time course of the phase angle deviation of an integrated generator model in which the entire power system is converted to one generator, stability is determined by estimating the time course of the phase angle deviation that reflects the first power restriction. When it is determined that the generator is in an unstable state where it is out of step, it becomes stable by repeating the selection of an additional shedding device, the estimation of the time course of the phase angle deviation that reflects the additional shedding, and the determination of stability. By selecting an additional power cutter and cutting off the additional power cutter from the power system following the first power cutoff, the generator will not step out even if the first power cutback becomes unstable. A stable state can be maintained. In addition, the determination reference value is adjusted according to the phase angle difference between the interconnection point and the unstable generator, and the calculation formula for estimating the change in the active power deviation _ΔPG of the integrated generator model after the measurement period is By using the coefficients, it is possible to prevent an unstable state from being incorrectly determined to be stable.

In the above embodiment, an example was shown in which stability is determined using the phase angle deviation Δδ of the integrated generator model. You can. In that case, the discrimination criterion obtained by the discrimination criterion formulation unit 43 will also be the one to which the phase angle initial value is added.

Further, in the above-described embodiment, an example was shown in which the information collection by the high-speed information collection unit 51 ends before the first electricity restriction implementation, but the information collection by the high-speed information collection unit 51 also ends after the first electricity restriction implementation. Information collection may also be performed. In that case, the active power deviation of the unstable generator group model due to the first power restriction is calculated based on the information from the high-speed information collection unit 51.

Moreover, in the above-mentioned embodiment, the example was shown in which the change in the active power deviation due to the first electric control is reflected and the phase angle deviation after the first electric control is calculated based on it. However, if the amount of change to be reflected is extremely small, such as when the amount of change is zero, it is not necessary to reflect the amount of change and calculate the phase angle deviation by the first electric control. In that case, only the additional electrical restriction may be executed without performing the first electrical restriction.

Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

1 Power system 2 Bus bar 3 Transmission line 4 Transformer 5 Generator 6 Circuit breaker 10 Transmission system 11 Information terminal 12 Control terminal 20 System stabilization device 30 Power control execution unit 40 Stability evaluation model generation unit 50 Additional power restriction execution unit

Claims (9)

By collecting system information including at least the active and reactive power of the transmission lines that make up the power system and building a system model, and performing transient stability calculations for assumed accident conditions in advance, generators can be A first electrically controlled generator is selected in advance to prevent out-of-step, and when a system fault occurs, the system can be disconnected by disconnecting the first electrically controlled generator that has been selected in advance. A system stabilizing device that prevents disturbances,
Model definition information for estimating the future value of phase angle deviation used to determine whether one or more generators included in the power system are out of synch before an accident occurs, and whether or not one or more generators included in the power system are out of synch. a stability evaluation model generation unit that prepares a discrimination reference value used for discrimination based on the result of the immediately preceding transient stability calculation;
After an accident occurs, the determination reference value prepared by the stability evaluation model generation unit is adjusted based on the measured values of the power system, and the measured values of the power system before and after the accident are incorporated into the model definition information. If it is determined that the generator included in the power system will step out of synchronization based on the future value of the phase angle deviation predicted by applying the adjustment and the determination reference value after the adjustment, an additional power-shutdown generator is determined. Additional electricity control execution unit to be selected,
A grid stabilizing device equipped with The additional electricity control execution unit is
Measured values of the power system before and after the occurrence of the accident, including at least the active power of each generator, the phase angle difference between the interconnection point and each generator, the voltage at the interconnection point, and the active power of the interconnection line, a high-speed information collection unit that collects the system information at a faster step size;
converting one or more generators included in the electric power system into one generator based on model definition information of the stability evaluation model generation unit and measured values for a certain period before and after the occurrence of the accident collected by the high-speed information collection unit; a generator state calculation unit that calculates or estimates the phase angle deviation of the integrated generator model;
an output change estimating unit that estimates a change in active power deviation of the integrated generator model due to disconnection of the first electrically limited generator and the additional electrically limited generator;
a discrimination reference adjustment unit that adjusts the discrimination reference value based on the interconnection point obtained from the high-speed information collection unit and the phase angle difference between each generator;
a stability determination unit that determines whether or not there is a step-out based on the phase angle deviation of the integrated generator model calculated or estimated by the generator state calculation unit and the determination reference value adjusted by the determination reference adjustment unit;
an additional breaker selection unit that selects an additional breaker generator when there is step-out;
Equipped with
The system stabilizing device according to claim 1. The stability evaluation model generation unit includes:
Based on the result of the transient stability calculation, one or more generators included in the power system are divided into an unstable generator group and a stable generator group, and the unstable generator group is converted into one generator. an unstable side system model formulation department that formulates model definition information for the unstable generator group model;
A function for estimating the total active power of stable generators in an external system based on the result of the transient stability calculation, and a model definition of a stable generator group model that converts the stable generator group into one generator. A stable system model formulation department that formulates information,
a discrimination criterion formulation unit that creates the discrimination criterion value based on the result of the transient stability calculation;
Based on the result of the transient stability calculation, determine a coefficient for calculating a change in active power deviation of the integrated generator model due to disconnection of the first electrically limited generator and the additional electrically limited generator. and an output change model formulation unit that maintains the output change model.
The model definition information for estimating the future value of the phase angle deviation used to determine whether or not one or more generators included in the power system are out of synchronization includes the model definition information of the unstable generator group model and the stable generator group model. and model definition information of the generator group model.
The system stabilizing device according to claim 2. The generator state calculation unit includes:
Unstable power generation that calculates the active power deviation of the unstable generator group model based on definition information of the unstable generator group model and measured values for a certain period before and after the occurrence of the accident collected by the high-speed information collection unit. computer calculation department,
Stable power generation that calculates the active power deviation of the stable generator group model based on the definition information of the stable generator group model, the function, and measured values for a certain period before and after the occurrence of the accident collected by the high-speed information collection unit. computer calculation department,
model definition information of the stability evaluation model generation section, active power deviation of the unstable generator group model of the unstable generator calculation section, and active power deviation of the stable generator group model of the stable generator calculation section; a phase angle deviation calculation unit that calculates a phase angle deviation of the integrated generator model based on;
a phase angle deviation coefficient calculation unit that calculates a first coefficient for estimating a future value of the phase angle deviation after the certain period of time based on the phase angle deviation calculated by the phase angle deviation calculation unit;
an adjustment necessity determination unit that adjusts a second coefficient for estimating a future value of the phase angle deviation after the certain period based on measured values for a certain period before and after the occurrence of the accident collected by the high-speed information collecting unit; ,
The model definition information of the stability evaluation model generation section, the change in active power deviation of the integrated generator model calculated by the output change estimation section, and the first difference calculated by the phase angle deviation coefficient calculation section. Based on the coefficient and the second coefficient adjusted by the adjustment necessity determination unit, a phase angle deviation of the integrated generator model that reflects the disconnection of the first power-shutdown generator and the additional power-shutdown generator. a phase angle deviation estimation unit that estimates the
The system stabilizing device according to claim 3. The phase angle deviation coefficient calculation unit calculates the first coefficient in advance further based on the active power deviation of the integrated generator model used to calculate the phase angle deviation.
The system stabilizing device according to claim 4. The adjustment necessity determination unit adjusts the second coefficient based on the voltage at the interconnection point and the active power of the interconnection line obtained from the high-speed information collection unit.
The system stabilizing device according to claim 4 or 5. The discrimination criterion adjustment section adjusts the discrimination criterion value obtained by the discrimination criterion formulation section based on the phase angle difference between the interconnection point and each unstable generator obtained from the high-speed information collection section.
The system stabilizing device according to any one of claims 3 to 6. By collecting system information including at least the active and reactive power of the transmission lines that make up the power system and building a system model, and performing transient stability calculations for assumed accident conditions in advance, generators can be A first electrically controlled generator is selected in advance to prevent out-of-step, and when a system fault occurs, the system can be disconnected by disconnecting the first electrically controlled generator that has been selected in advance. A system stabilizing device that prevents
Model definition information for estimating the future value of phase angle deviation used to determine whether one or more generators included in the power system are out of synch before an accident occurs, and whether or not one or more generators included in the power system are out of synch. A discrimination reference value used for discrimination is prepared based on the result of the immediately preceding transient stability calculation,
After the accident occurs, the phase angle predicted by adjusting the discrimination reference value prepared based on the measured values of the power system and applying the measured values of the power system before and after the accident to the model definition information. Selecting an additional curtailment generator when it is determined that the generator included in the power system will step out of synchronization based on the future value of the deviation and the determined reference value after the adjustment;
System stabilization method. By collecting system information including at least the active and reactive power of the transmission lines that make up the power system and building a system model, and performing transient stability calculations for assumed accident conditions in advance, generators can be A first electrically controlled generator is selected in advance to prevent out-of-step, and when a system fault occurs, the system can be disconnected by disconnecting the first electrically controlled generator that has been selected in advance. In the processor of the grid stabilization device that prevents
Model definition information for estimating the future value of phase angle deviation used to determine whether one or more generators included in the power system are out of synch before an accident occurs, and whether or not one or more generators included in the power system are out of synch. A discrimination reference value used for discrimination is prepared based on the result of the immediately preceding transient stability calculation,
After the accident occurs, the phase angle predicted by adjusting the discrimination reference value prepared based on the measured values of the power system and applying the measured values of the power system before and after the accident to the model definition information. selecting an additional curtailment generator when it is determined that a generator included in the power system is out of synchronization based on a future value of the deviation and the adjusted determination reference value;
program.

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