JP2014054093A - Contraction model creation device, creation method, and creation program for power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To create a contraction system mode of high robustness or accuracy even in the case where the number of motors to be operated is changed, a control system operation of an equivalent contraction motor is brought into a nonlinear range by large disturbance, or online information of an external system is limited.SOLUTION: A contraction model creation device comprises: a contraction model creation section 11 for creating a contraction system model from a source system model of a power system; a source system stability limit tide calculation section 123 for calculating a stability limit tide of the source system model on the basis of tide cross section data and assumed accident cases; a contraction system stability limit tide calculation section 124 for calculating a stability limit tide of the contraction system model on the basis of tide cross section data, assumed accident cases, and a control system constant; a differential computation section 125 for computing a differential between the stability limit tide of the contraction system model and the stability limit tide of the source system model; and a constant estimation section 126 for estimating, on the basis of the differential, such a control system constant that the stability limit tide of the contraction system model becomes equal to or less than the stability limit tide of the source system model.

Description

  Embodiments described herein relate generally to a reduced model creation apparatus, a creation method, and a creation program that reduce a power system model.

  A power system model is used for analyzing an accident phenomenon of the power system and stabilizing calculation of the accident spread prevention system. This power system model is information obtained by modeling a connection state of a generator or the like in the power system.

  In recent years, however, power systems have become larger and more complex. For this reason, the power system model obtained by modeling the power system is also increased in scale and complexity. As described above, the calculation based on the large-scale and complicated power system model causes an increase in processing load and a delay.

  Therefore, a reduction method for creating a reduced system model by simplifying the original system model that is the original power system model in advance is used. Conventional reduction methods include a short-circuit capacity method, a short-circuit current method, and a two-load method. By using such a reduction method, it is possible to create a small reduced system model that can be simulated efficiently.

  Reduction of the power system model includes reduction of the control system of the generator. A generator control system includes AVR, PSS, GOV, and the like. AVR is an automatic voltage regulator, PSS is a system stabilizer, and GOV is a governor. These control systems can be expressed by control blocks of a transfer function model. Each control block has a time constant and a gain as constants used for calculation.

In the reduced system model, the reduced generator is called an equivalent reduced generator. The control system in this equivalent contraction generator can be contracted by expressing it by the following two methods.
(1) Represent the control system of the largest power generation unit in the contracted system.
(2) If the control block configuration of each generator control system to be reduced is the same, each time constant and gain in the control block of the equivalent reduced generator is the logarithm of each time constant and gain of the reduced generator. Expressed as a weighted average.

  In addition, in the online pre-computation type accident spill prevention system that performs stability calculation by using system information obtained online in advance and creates a control table, it is a wide area link that connects power systems of multiple power companies. It often deals with the system. Even in such an online pre-calculation type accident spill prevention system, simulation is performed at high speed using a reduced system model.

  In this case, the reduced system model is created in advance offline using the original system model in a certain system state. Based on the online information, the model is updated to match the state of the real system that changes from moment to moment. Online information includes supervision (SV) information including circuit breaker switching information and telemeter (TM) information including measurement information such as voltage, current, and power.

  An example of such a model update method is shown below. First, an external system model corrected to the current generator parallel state is generated using all generator data of the external system, control system data, and generator parallel solution information (SV information) of the external system online information. . Then, using this external system model, the generator constants such as the rated capacity and internal impedance of the equivalent contracted generator and the control system constants are calculated by the existing contraction method such as the short-circuit capacity method or the two-load method.

Electric Cooperative Research Vol. 34, No. 5, “Stability of Power System”, Electric Cooperative Research Society, January 25, 1979, p. 24-25

Japanese Patent Application Laid-Open No. 10-56735

Incidentally, the creation of the reduced system model as described above has the following problems.
(1) When represented by the maximum power generation unit in the reduction target system In this case, if there are many control systems of the same type, or if the rated capacity of the maximum power generation unit is large in the total generator capacity of the reduction target system, no problem. However, when the number of control systems of the same type is small or when the number of operating generators is changed, the ratio of the maximum power generation unit to the total generator capacity becomes small and it is not dominant in the target system. For this reason, even if the maximum power generation unit is represented, the accuracy of the reduced system model with respect to the original system model may be reduced.

(2) When the gain and time constant of the control system block of the equivalent contracted generator are set to the logarithm weighted average value of the generator in the contracted system In this case, the accident phenomenon is a slight disturbance and the control system There is no problem when the operation is in the linear range. However, if the influence of nonlinear elements of the control system becomes large due to a large disturbance, the accuracy of the reduced system model may be reduced.

(3) When updating the control system constants in the online pre-computed accident prevention system In this case, all generator data and control system data of the external system and all power generation of the external system are used as online information of the external system. It is necessary to use SV information of the machine.

  For this reason, when the scale of the external system is large, a great amount of equipment data and online information are required. For example, if there are 100 generators in the contraction target system, generator data for 100 units, control system data, and 100 amounts of SV information are required.

  In addition, since online information such as SV information and TM information of external systems is not protected by the accident spread prevention system, not all information is obtained and information is often limited. In that case, the demand for the actual power system changes from moment to moment, and even though the output of the generator and the number of operating units change accordingly, the control system constants and generator constants of the equivalent reduced generator Cannot update.

  In this way, in order to create a reduced system model suitable for a changing real system based on limited information, AVR, PSS, GOV with high robustness that can obtain an optimum result even if there is a change It is necessary to use a control system such as

  Embodiments of the present invention have been proposed to solve the above-described problems of the prior art, and the purpose of the embodiment is to reduce the number of generators to be changed by large disturbances and equivalent reduced generators. When the control system operation of the system is in a non-linear range, even if the online information of the external system is limited, a reduced model creation device, creation method, and creation program for a power system that can create a reduced system model with high robustness and accuracy Is to provide.

An embodiment for achieving the above object has the following configuration.
(1) Reduced model creation unit that creates a reduced system model from the original power system model
(2) Control system constant tuning unit for adjusting the control system constant of the reduced system model

Further, the control system constant tuning unit has the following configuration.
(a) a tidal current section data setting unit for setting a plurality of tidal current section data;
(b) an assumed accident case setting unit for setting a plurality of assumed accident cases;
(c) Main system stability limit tidal current calculation unit that calculates the stability limit tidal current of the main system model based on the tidal current cross section data and the assumed accident case
(d) A reduced system stability limit power flow calculation unit that calculates a stable limit power flow of the reduced system model based on the cross section of the power flow, the assumed accident case, and the control system constant.
(e) A difference calculation unit that calculates a difference between the stability limit current of the reduced system model and the stability limit current of the original system model
(f) Based on the difference, a constant estimation unit that estimates a control system constant at which the stable limit flow of the reduced system model is equal to or less than the stable limit flow of the original system model
(g) A constant output unit that outputs the control system constant estimated by the constant estimation unit

  Note that this embodiment can also be understood as a method for realizing the functions of the above-described units by a computer or an electronic circuit, and a program for causing a computer to execute the functions of the above-described units.

The block diagram which shows the structure of 1st Embodiment. Block diagram showing the constant estimation unit of FIG. Block diagram showing the constant output unit of FIG. The flowchart which shows the flow of a process of embodiment of FIG. The figure which shows an example of the transfer function model (control block) of PSS which made the generator output effective part P into the input The figure showing an example of the calculation result of ΔPu The figure which shows an example of the relationship between PSS gain and (DELTA) Pu The figure which shows an example which determines an adjustment value from several Gpss' The block diagram which shows the constant estimation part of 3rd Embodiment The figure which shows an example which determines an adjustment value from several PSS constant pattern The block diagram which shows the constant output part of 4th Embodiment

[First Embodiment]
[overall structure]
The configuration of this embodiment will be described with reference to FIGS. The contracted model creating apparatus 1 of the present embodiment includes a contracted model creating unit 11 and a control system constant tuning unit 12. Further, the contracted model creation device 1 includes an original system model storage unit 21, a contracted system model storage unit 22, a tidal current section data storage unit 23, an accident data storage unit 24, and a setting storage unit 25. Further, the contracted model creation apparatus 1 includes an input unit 30 and an output unit 40.

  The contracted model creation unit 11 is a processing unit that creates a contracted system model obtained by contracting the original system model. The original system model is information that models the power system to be reduced. The original system model includes, for example, information on a generator, a bus, a power transmission line, a load, a transformer, a control system in the power system, and information indicating a connection state thereof.

  The reduced system model is a model in which generator groups with coherence are combined into one, and buses, transmission lines, loads, transformers, and control systems related to this are combined into one. Coherence is the basic concept for determining the system reduction area. A sub-system consisting of a group of generators that is similar to the disturbance of the active / reactive power of the generator and the fluctuation of the internal phase difference angle against disturbance. It is called a coherence-reducible region. As a contraction method by the contraction model creation unit 11, a known method such as a short-circuit capacity method, a short-circuit current method, or a two-load method can be applied.

  The control system of the equivalent reduced power generator in which the power generator is reduced can be represented by, for example, the control system of the maximum power generation unit in the reduction target system and its constant (control system constant). These constants include PSS, AVR, and GOV gains and time constants. Further, when there are a plurality of control systems of the same type in the contracted system, the control system and its constants may be selected by adding the rated capacity of the generators to be regarded as one generator.

  Furthermore, if the configuration of the control system block of each generator of the reduction target system is the same or can be regarded as the same, calculate the weighted average value of the gain of the control system block, the logarithm weighted average value of the time constant, It may be the control system constant of the equivalent reduced generator.

  The control system constant tuning unit 12 adjusts the control system constants of the equivalent contracted generator created by the contracted model creating unit 11 by the processing of each unit described later so that the accuracy of the contracted system model is improved. It is.

  The original system model storage unit 21 is a processing unit that stores an original system model to be reduced by the reduced model creation unit 11. The reduced system model storage unit 22 is a processing unit that stores the reduced system model created by the reduced model creation unit 11.

  The tidal current section data storage unit 23 is a processing unit that stores tidal current section data of the power system. The tidal current cross section data is information for obtaining a tidal current cross section indicating a tidal current distribution of reactive power and active power at a certain point in the power system. Specifically, the amount of power and the amount of load per unit time are included. A set order is set in advance for each tidal current section data.

  The accident data storage unit 24 is a processing unit that stores accident data in the power system. Accident data is information on accidents that can be assumed in the system, and includes accident points and aspects. For example, the accident point is information such as how many accidents occur on the transmission line, and the accident aspect is information such as how many lines and how many ground faults occur. A set order is set in advance for each accident data.

  The setting storage unit 25 is a processing unit that stores various types of information necessary for processing of the contracted model creation device 1. The information stored in the setting storage unit includes arithmetic expressions, parameters, and reference values (including threshold values) for processing of each unit. For example, power adjustment data such as power generation adjustment amount and load adjustment amount in stability calculation described later, change amount such as increment or decrement when changing constant, constant adjustment data such as upper and lower limits of constant after change are also set The storage unit 25 stores it.

  The input unit 30 is a processing unit that inputs information necessary for the contracted model creation apparatus 1, selects processing, gives instructions, and the like. The information stored in each storage unit can be information input from the outside via the input unit 30. Examples of the input unit 30 include a keyboard, a mouse, a touch panel (including those configured in a display device), and the like. The input unit 30 also includes an interface that receives information from the communication network and inputs the information to the contracted model creating apparatus 1.

  The output unit 40 stores information, calculation results, and the like that are the processing target of the reduced model creation device 1 such as the original system model, the reduced system model, the tidal current section, the assumed accident case, the stable limit tidal current, the difference, the constant, etc. And so on, so that the user can recognize them. Examples of the output unit 40 include a display device and a printer.

[Control system constant tuning section]
The control system constant tuning unit 12 includes a tidal current section data setting unit 121, an assumed accident case setting unit 122, an original system stability limit tidal current calculation unit 123, a reduced system stability limit tidal current calculation unit 124, a difference calculation unit 125, and a constant estimation unit 126. And a constant output unit 127.

  The tidal current section data setting unit 121 is a processing unit that sets tidal current section data in the original system model and the reduced system model in accordance with a preset order based on the tidal current section data stored in the tidal current section data storage unit 23. is there.

  The assumed accident case setting unit 122 sets an assumed accident case that is an accident assumed in the original system model and the reduced system model in accordance with a preset order based on the accident data stored in the accident data storage unit 24. Is a processing unit.

  The original system stability limit power flow calculation unit 123 is a processing unit that calculates the stability limit power flow of the original system model. This calculation is performed by repeatedly executing the power flow calculation and stability calculation of the power system model in the power flow section and assumed accident case set in the power system model.

  That is, the main system stability limit tidal current calculation unit 123 has 24 hours based on the connection relation of the generator, bus, transmission line, load, transformer, etc. of the main system model, the power generation amount from the tidal current cross section data, and the load amount. Perform tidal calculations to determine the current cross section.

  Further, the original system stability limit tidal current calculation unit 123 performs stability calculation to calculate the response of the generator in the tidal current section when an accident of the assumed accident case occurs. In this stability calculation, for example, a limit point at which the generator does not step out can be obtained in the tidal current section. In addition, the method of tidal current calculation and stability calculation is known.

  The contracted system stability limit power flow calculation unit 124 is a processing unit that calculates the stability limit power flow of the contracted system model. In this calculation, the tidal current calculation and stability calculation of the reduced system model are repeatedly executed using the tidal current cross section set in the reduced system model, the assumed accident case, and the constants of the control system of the equivalent reduced generator as parameters. Is done. The method of tidal current calculation and stability calculation is the same as above.

  The difference calculation unit 125 calculates a difference between the stability limit current of the original system model calculated by the original system stability limit power flow calculation unit 123 and the stability limit power flow of the contracted system model calculated by the reduced system stability limit power flow calculation unit 124. It is a processing part to calculate.

  The constant estimation unit 126 associates the difference between the stability limit currents of the original system model and the reduced system model and the control system constants of the reduced system model so that the stability limit current of the reduced system model is the same as that of the original system model. It is a processing unit that estimates a constant that is less than or equal to the stability limit flow.

  The constant estimation unit 126 includes a function generation unit 126a and a constant calculation unit 126b as shown in FIG. The function generation unit 126a is a processing unit that generates a linear function representing the relationship between the difference and the constant. This linear function is, for example, a linear interpolation formula between two points as described later. The constant calculation unit 126b is a processing unit that obtains a constant whose difference is zero based on the linear function generated by the function generation unit 126a.

  The constant output unit 127 is a processing unit that outputs a constant of the adjustment result. As shown in FIG. 3, the constant output unit 127 has a minimum value selection unit 127a. The minimum value selection unit 127a is a processing unit that selects the minimum value among the constants for each assumed accident case of each tidal current section obtained by the constant calculation unit 126b.

  The contracted model creating apparatus 1 can be realized by controlling a computer including a CPU with a predetermined program. The above program realizes processing of each unit by physically utilizing hardware. For this reason, said apparatus structure is an illustration to the last, and it is not limited to a specific aspect about which function of the hardware which comprises a system bears.

  Furthermore, an apparatus, a method, a program, and a recording medium that records the program for executing the processing of each unit are also one aspect of the embodiment. How to set the range to be processed by hardware and the range to be processed by software including a program is not limited to a specific mode. For example, any one of the units can be configured as a circuit that realizes each process.

[Action]
The operation of the present embodiment as described above will be described with reference to the flowchart of FIG. The following description is an example in the case of obtaining a PSS constant as an adjustment result. The PSS is a control system that attenuates fluctuations between generators as an auxiliary input to the AVR of the generator.

  First, the tidal current section data setting unit 121 takes out tidal current cross section data stored in the tidal current section data storage unit 23 according to the set order, and sets the tidal current cross sections of the original system model and the reduced system model (step S10). .

  Further, the assumed accident case setting unit 122 takes out the accident data stored in the accident data storage unit 24 according to a preset order, and sets an assumed accident case to be simulated with the original system model and the reduced system model (step) S11).

  Here, if all possible accident aspects are targeted, a large number of cases of stability calculation are executed, which is inefficient. For this reason, it is possible to adjust the control system constants only with the most severe accident aspect in terms of transient stability, and to reduce the number of executions of stability calculation.

  The severity of the accident is the magnitude of the effect on the power system. For example, 3φ4LG is more severe than 2φ3LG, and if 3φ4LG occurs, it has a greater impact on the power system.

  Then, the original system stability limit tidal current calculation unit 123 repeatedly executes tidal current calculation and stability calculation using the original system model, and obtains the system condition at the limit point where the transient stability of the assumed accident case is maintained (step) S12). Here, the limit point at which the transient stability is maintained is a point where the generator does not step out. The grid condition is a tidal current cross section.

  If the stability calculation result is unstable and the generator is out of phase, the power generation amount is set so that the tidal current at the accident point decreases based on the power generation adjustment amount and load adjustment amount in the set tidal current adjustment data. And adjust the load.

  When the stability calculation result is stable and the generator does not step out, the power generation amount and the load flow adjustment amount are set so that the tidal current at the accident point increases based on the power generation adjustment amount and load adjustment amount in the set tidal current adjustment data. Adjust the load.

  Then, the tidal current calculation and the stability calculation are executed again with the adjusted original system model. By repeating this, the tidal current cross section, which is the system state at the limit point where the transient stability is maintained, is obtained. The tidal current in the state before the accident occurs at the point of the accident at this time is called a prior tidal current. This prior tidal current is the stability limit tidal current Pu.

  In addition, the original system stable limit power flow calculation unit 123 may calculate the limit point based on the fluctuation state of the generator internal phase difference angle instead of the presence or absence of step-out. For example, when the generator internal phase difference angle fluctuates due to an accident, the attenuation rate of the amplitude is calculated, and when the attenuation rate tends to increase, it can be determined that the fluctuation is toward vibration divergence and is unstable. .

  On the other hand, when the attenuation rate tends to decrease, it can be determined that the fluctuation is stable because the fluctuation is toward convergence. The original system stability limit power flow calculation unit 123 calculates the boundary between stability and instability as a limit point based on a threshold value or the like. In this case, the tidal current in the state before the limit point is the prior tidal current, that is, the stable limit tidal current Pu.

  On the other hand, the reduced system stability limit power flow calculation unit 124 calculates the stable limit power flow Pu 'of the contracted system model using the same method as the original system model (step S13). The same applies when the limit point is calculated based on the fluctuation state of the generator internal phase difference angle. However, the reduced system stability limit power flow calculation unit 124 calculates the stable limit power flow Pu ′ using the constant of the control system of the equivalent reduced power generator as a parameter.

  For example, the reduced system stability limit power flow calculation unit 124 calculates the stable limit power flow Pu ′ using the PSS gain of the equivalent reduced power generator as a parameter. Here, FIG. 5 shows an example of a control block which is a PSS transfer function model using the generator output effective amount P as an input.

  The detector C1 simulates a time delay for measuring the active power using the active power of the generator as an input. The signal reset circuit C2 is a high-pass filter that removes a DC component and outputs a fluctuation amount of an input signal. The phase compensation C3 and C4 compensate the phase for each frequency domain of the input signal using time constants T1 to T4. The PSS gain C5 is a value for adjusting the strength of the output. C6 is a limiter.

  The stable limit power flow Pu 'is calculated by changing the PSS gain Gpss based on the set constant adjustment data of the PSS. First, the stable limit power flow Pu ′ in the reduced system model is calculated without changing the PSS gain Gpss.

  Next, the PSS gain Gpss is increased by the PSS constant adjustment data (Gpss + ΔGpss), and the stable limit power flow Pu ′ is calculated using a reduced system model in which the PSS constant is changed. The PSS gain Gpss is increased in increments of PSS constant adjustment data (ΔGpss), and the stable limit power flow Pu ′ is calculated for each increment.

  When the changed PSS gain Gpss reaches the upper limit value of the set adjustment, the PSS gain Gpss is decreased by the PSS constant adjustment data (Gpss−ΔGpss), and the stable limit power flow Pu is obtained with the reduced system model in which the PSS constant is changed. 'Is calculated. The PSS gain Gpss is decreased in increments of PSS constant adjustment data (ΔGpss), and the stable limit power flow Pu ′ is calculated for each increment. When the changed PSS gain Gpss reaches the lower limit value of the set adjustment, the calculation of the stable limit power flow Pu 'is terminated.

  As described above, the stability limit power flow Pu of the original system model and the stability limit power Pu ′ of the reduced system model are calculated until the constant reaches the upper and lower limits (NO in step S14, step S13).

  When the constant reaches the upper and lower limits and the calculation of the stable limit currents Pu and Pu ′ is completed (YES in step S14), the difference calculation unit 125 calculates the difference ΔPu (= Pu) between the original system model and the reduced system model. Pu′−Pu) is calculated (step S15).

  The constant estimation unit 126 associates the difference ΔPu and the PSS constant, and estimates a constant at which the stable limit power of the reduced system model is equal to or less than the stable limit power of the original system model. This estimation process will be described below.

  First, when the difference ΔPu is a negative value, it can be determined that the reduced system model is lower than the original system model with respect to the stability limit point indicated by the stability limit power flow. When the difference ΔPu is a positive value, it can be determined that the stability limit point is higher in the reduced system model than in the original system model.

  An example of the calculation result of such a difference ΔPu is shown in FIG. If the difference ΔPu is a positive value and the reduced system model has a higher stability limit, it is possible to misunderstand that the reduced system model is “stable”, although the original system model should be “unstable” There is sex. For this reason, the stability limit point of the reduced system model needs to be the same as or slightly lower than the original system model.

  Here, the function generation unit 126a of the constant estimation unit 126 associates ΔPu with the PSS gain, and generates a linear interpolation expression representing the relationship between ΔPu and the PSS gain (step S16). Then, the constant calculation unit 126b obtains a PSS gain at which ΔPu becomes zero using the linear interpolation equation generated by the function generation unit 126a (step S17).

  FIG. 7 shows an example of graphing the result of associating ΔPu with the PSS gain for the ΔPu calculation result of FIG. FIG. 7 shows the relationship between the difference ΔPu and the PSS gain Gpss when they are rearranged in ascending order with the difference ΔPu in FIG. 6 as the vertical axis (x axis) and the PSS gain Gpss as the horizontal axis (y axis). Is.

  This example is linear interpolation between two points of (x0, y0) = (1.05, −30) and (x1, y1) = (1.1, 5). That is, a value at which ΔPu is zero (x, y) = (Gpss ′, 0) is obtained by the linear interpolation equation (y−y0) / (y1−y0) = (x−x0) / (x1−x0). .

This is expressed by the following formula (1).
Gpss ′ = (0.05 / 35) * 30 + 1.05 = 1.093 (1)
As a result, the PSS gain Gpss ′ at which the difference ΔPu is zero, that is, the stability limit points of the original system model and the contracted system model coincide, can be estimated. The obtained position (x, y) = (Gpss ′, 0) is indicated by a circle in FIG.

  Next, when the set accident case still exists (NO in step S18), the processes of steps S11 to S17 are performed, and the PSS gain Gpss ′ at which the difference ΔPu becomes zero is set for each assumed accident case. calculate. When the calculation of the PSS gain Gpss ′ for all the assumed accident cases is completed (YES in step S18) and there is another tidal section (NO in step S19), this is set (step S10). ).

  Then, the processes of steps S10 to S19 are performed until the calculation of the PSS gain Gpss ′ is completed for all tidal current cross sections. As described above, the PSS gain Gpss ′ at which ΔPu becomes zero is calculated for each assumed accident case for all tidal current cross sections (YES in step S19).

  Then, the constant output unit 127 outputs the calculated PSS gain Gpss ′ (step S20). However, the minimum value selection unit 127a of the constant output unit 127 selects the minimum value from all the calculated PSS gains Gpss 'as the PSS gain Gpss' to be output.

  For the sake of simplification, graphs show the results of associating ΔPu with the PSS gain for the A transmission line accident at the A tidal section, the B transmission line accident at the B tidal section, and the C transmission line accident at the C tidal section. An example of this is shown in FIG. FIG. 8 shows the relationship between the difference ΔPu and the PSS gain Gpss in the ascending order with the vertical axis (x axis) as the difference ΔPu and the horizontal axis (y axis) as the PSS gain Gpss as ■, ◆, and ▲. It is a thing.

  The obtained three PSS gains Gpss' are indicated by ◯ in FIG. When determining from these three PSS gains Gpss ′, it can be said that Gpss ′ = 1.075 of the B transmission line of the B section is the minimum value. Therefore, the minimum value selection unit 127a selects this Gpss ′.

[effect]
According to the present embodiment as described above, an adjusted constant can be obtained based on a plurality of tidal current cross sections and an assumed accident case. For this reason, it is possible to create a reduced system model with high robustness and high accuracy that can obtain an optimum result suitable for a changing actual system such as the number of operating generators is changed.

  Moreover, the constant can be adjusted so that the difference between the stability limit current of the original system model and the contracted system model becomes small by using the stability limit current, which is an index that quantitatively indicates the stability limit of transient stability. . For this reason, even if it is an accident case where the influence of the nonlinear element of a control system becomes large by a large disturbance, the constant which can respond can be set.

  In addition, the constant at which the difference becomes zero can be estimated from a linear function representing the relationship between the difference between the stability limit power flow of the original system model and the reduced system model and the constant. For this reason, the number of executions of stability calculation for calculating the stability limit power flow can be reduced, and an adjustment result can be obtained efficiently and at high speed.

  Also, even when external system online information is restricted, constants with high robustness can be obtained, so external system online information, generator data, and control system data are obtained to update control system constants. It becomes unnecessary.

  Furthermore, when calculating the stable limit power flow based on the fluctuation state of the generator internal phase difference angle rather than the presence or absence of step-out, the fluctuation state of the generator before the step-out is taken as the limit point, so it is more reliable. Thus, a constant that can prevent step-out can be obtained.

[Second Embodiment]
This embodiment is basically the same configuration as the first embodiment. However, the constants to be adjusted in the present embodiment are the gain and time constant of the PSS constant. Hereinafter, only processing (corresponding to step S13 in FIG. 4) different from that of the first embodiment will be described.

  That is, the reduced system stability limit power flow calculation unit 124 calculates the stable limit power flow Pu ′ of the reduced system model using the gain and time constant of the PSS constant as parameters. For example, the case of the P-type PSS transfer function model illustrated in FIG. 5 will be described. In this case, the stable limit power flow Pu 'when the PSS gain Gpss and the phase compensation time constants T1, T2, T3, and T4 are changed based on preset PSS constant adjustment data is calculated.

  First, the reduced system stability limit power flow calculation unit 124 calculates the stability limit power flow Pu ′ without changing each constant. Next, each constant is increased by the constant adjustment data of PSS (Gpss + ΔGpss, T1 + ΔT1, T2 + ΔT2, T3 + ΔT3, T4 + ΔT4), and the stable limit power flow Pu ′ is calculated with the reduced system model in which the PSS constant is changed.

  Each constant is increased in increments of PSS constant adjustment data (ΔGpss, ΔT1, ΔT2, ΔT3, ΔT4), and the stable limit power flow Pu 'is calculated for each increment. When the changed constant reaches the preset upper limit value, each constant is decreased by the constant adjustment data of PSS (Gpss-ΔGpss, T1-ΔT1, T2-ΔT2, T3-ΔT3, T4-ΔT4), A stable limit power flow Pu ′ is calculated for each step.

  When the changed PSS gain and time constant reach the lower limit value, the calculation of the stable limit power flow Pu 'is terminated. In this example, all constants are changed. However, some constants may be changed.

  After that, as in the first embodiment, a combination of constants at which the difference between the stable limit power flows becomes zero and the PSS gain Gpss' becomes the minimum value is output.

  According to the present embodiment as described above, the same effects as those of the first embodiment can be obtained, and the time constant is adjusted together with the gain of the PSS, so that the accuracy of simulation using the reduced system model is further improved.

[Third Embodiment]
[Constitution]
This embodiment is basically the same configuration as the first embodiment. However, in the present embodiment, a plurality of PSS constant patterns are set in the setting storage unit 25 in advance. Then, the reduced system stability limit power flow calculation unit 124 calculates the stable limit power flow Pu ′ of the reduced system model when the PSS constant of the equivalent reduced power generator is replaced with each constant pattern.

  As shown in FIG. 9, the constant estimation unit 126 includes a negative value pattern selection unit 126c and a minimum pattern selection unit 126d. The negative value pattern selection unit 126c is a processing unit that selects a constant pattern in which the differences ΔPu are all negative values. The minimum pattern selection unit 126d is a processing unit that selects a constant pattern having the smallest absolute value of the minimum value of each difference ΔPu.

[Action]
The operation of the present embodiment as described above will be described. Note that description of operations similar to those of the first embodiment is omitted.

  That is, the reduced system stability limit power flow calculation unit 124 uses the plurality of PSS constant patterns to calculate the stable limit power flow Pu ′ of the reduced system model when the PSS constant of the equivalent reduced power generator is replaced with each constant pattern. calculate.

  The difference calculation unit 125 calculates the difference ΔPu between the stability limit tidal currents of the original system model and the reduced system model. The calculation of the difference ΔPu is performed for all tidal current cross sections and assumed accident cases set in advance as in the first embodiment.

  As described above, when the calculation of ΔPu is completed for all the tidal current sections and the assumed accident cases, the negative value pattern selection unit 126c collects the differences ΔPu for each constant pattern, and generates a negative value pattern in which the differences ΔPu are all negative values. select. FIG. 10 shows an example determined from the four constant patterns 1 to 4. Among these four constant patterns 1 to 4, the negative value patterns are the constant patterns 1, 2, and 4 indicated by black arrows in the figure.

  Further, the minimum pattern selection unit 126d compares the minimum values of the differences ΔPu in the negative value pattern selected by the negative value pattern selection unit 126c, and selects the negative value pattern including the difference ΔPu having the smallest absolute value. To do. In the example of FIG. 10, a negative value pattern corresponding to the constant pattern 2 indicated by the white arrow in the drawing is selected.

  The constant output unit 127 outputs a constant pattern corresponding to the negative value pattern selected by the minimum pattern selection unit 126d as the adjustment result of the PSS constant. In FIG. 10, since the constant pattern 2 corresponds to the selected negative value pattern, the constant pattern 2 is output as the adjustment result of the PSS constant.

[effect]
According to the present example, the same effect as that of the first embodiment can be obtained, and a constant pattern in which the stability limit point is lower in the reduced system model than in the original system model can be selected without fail.

[Fourth Embodiment]
[Constitution]
This embodiment is basically the same configuration as the first embodiment. However, in this embodiment, as shown in FIG. 11, the constant output unit 127 includes a confirmation unit 127b in addition to the minimum value selection unit 127a. The confirmation unit 127b is a processing unit that instructs the calculation of the stable limit power flow of the reduced system model in all power flow cross sections and assumed accident cases based on the constant estimated by the constant estimation unit 126. And the confirmation part 127b confirms that the difference of the stability limit tidal current with an original system | strain model will be zero or less.

[Action]
The operation of this embodiment is as follows. That is, the confirmation unit 127b instructs the contracted system stable limit flow calculation unit 124 to calculate the stable limit flow Pu ′ based on the adjustment value selected by the minimum value selection unit 127a. The reduced system stability limit power flow calculation unit 124 calculates the stability limit power flow Pu ′ again for all power flow cross sections and assumed accident cases.

  Then, the difference calculation unit 125 compares the stable limit power flow Pu ′ with the stable limit power flow of the original system model to obtain a difference ΔPu. The confirmation unit 127b confirms whether or not the difference ΔPu is less than or equal to zero.

[effect]
According to the present embodiment as described above, it can be confirmed that the stability limit point of the reduced system model is the same as or lower than that of the original system model, even if the constant estimated by the linear function is used. For this reason, since it can be determined whether the calculation result is applicable, the reliability of the processing result is improved.

[Other Embodiments]
(1) The combination of each said embodiment is free. For example, a combination of the second embodiment and the third embodiment, a combination of the second embodiment and the fourth embodiment, and a combination of the third embodiment and the fourth embodiment can be configured. is there.

(2) The adjustment target according to the present embodiment is not limited to the PSS constant exemplified in the above embodiment. For example, constants such as AVR and GOV can be adjusted.

(3) Each unit described above may be realized by common hardware, or may be realized by a plurality of hardware connected by a communication network. For example, the contracted model creation unit and the control system constant tuning unit may be configured by separate computers, or any of the various storage units described above may be configured by an independent server.

(4) The various storage units described above can typically be configured by various built-in or externally connected memories, a hard disk, an optical disk, and the like. However, any storage medium that can be used now or in the future can be used as the storage unit. A register or the like used for calculation can also be regarded as a storage unit. A mode in which a storage medium in which information has already been stored can be used for computation by being mounted on a reading device may be employed. The mode of storage includes not only a mode in which memory is stored for a long time, but also a mode in which data is temporarily stored for processing and deleted or updated in a short time.

(5) The specific contents and values of the information used in the embodiment are free and are not limited to specific contents and numerical values. In the embodiment, in the determination of the magnitude of the value, the determination of coincidence / mismatch, and the like, it is determined that the value is included as follows, or is determined not to include the value as larger (exceeded) or smaller (not exceeded). It is also free.

(6) The calculation method for the generation of a contracted model, tidal current calculation, stability calculation, etc. is not limited to a specific one, and includes any technique that can be applied at present or in the future.

(7) Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Reduced model creation apparatus 11 ... Reduced model creation part 12 ... Control system constant tuning part 21 ... Original system model memory | storage part 22 ... Reduced system model memory | storage part 23 ... Tidal current section data memory | storage part 24 ... Accident data memory | storage part 25 ... Setting storage section 30 ... Input section 40 ... Output section 121 ... Tidal section data setting section 122 ... Assumed accident case setting section 123 ... Original system stability limit tidal current calculation section 124 ... Reduced system etc. stable limit tidal current calculation section 125 ... Difference calculation Unit 126 ... constant estimation unit 126a ... function generation unit 126b ... constant calculation unit 126c ... negative value pattern selection unit 126d ... minimum pattern selection unit 127 ... constant output unit 127a ... minimum value selection unit 127b ... confirmation unit

Claims (9)

A reduced model creation unit that creates a reduced system model from the original system model of the power system;
A control system constant tuning unit for adjusting a control system constant of the reduced system model;
Have
The control system constant tuning unit is
A tidal section data setting unit for setting a plurality of tidal section data;
An assumed accident case setting unit for setting a plurality of assumed accident cases;
Based on the tidal current cross section data and the assumed accident case, the main system stability limit tidal current calculation unit that calculates the stability limit tidal current of the original system model,
A reduced system stability limit power flow calculation unit for calculating a stable limit power flow of the reduced system model based on the power flow cross-sectional data, the assumed accident case, and the control system constant;
A difference calculation unit for calculating a difference between the stability limit current of the reduced system model and the stability limit current of the original system model;
Based on the difference, a constant estimation unit that estimates a control system constant at which the stability limit power of the reduced system model is equal to or less than the stability limit power of the original system model;
A constant output unit that outputs a control system constant estimated by the constant estimation unit;
An apparatus for creating a reduced model of a power system, comprising: The constant estimator is
A function generator for generating a linear function representing the relationship between the difference and the control system constant;
Using the linear function, a constant calculation unit for obtaining a control system constant at which the difference becomes zero;
The reduced model creation device for an electric power system according to claim 1, wherein:   The power system reduction according to claim 1, wherein the constant output unit includes a minimum value selection unit that selects a minimum value of control system constants estimated by the constant estimation unit. Model creation device. The reduced system stability limit power flow calculation unit is set to calculate a stability limit power flow using a constant pattern including a plurality of control system constants,
The constant estimator is
A negative value pattern selection unit that selects a constant pattern in which the differences are all negative values;
A minimum pattern selection unit for selecting a constant pattern having the smallest absolute value of the minimum value of the difference;
The reduced model creation device for an electric power system according to claim 1, wherein:   5. The reduced system model creation device for a power system according to claim 1, wherein the control system constant includes a gain and a time constant.   6. The power system according to claim 1, wherein the assumed accident case set by the assumed accident case setting unit is an accident sequence corresponding to an accident aspect having the most severe transient stability. Reduced model creation device. The constant output unit is:
Based on the control system constant estimated by the constant estimator, the reduced limit system stable limit power flow calculation unit again calculates the stable limit power flow of the reduced system model in all tidal current cross-section data and assumed accident cases, The reduced model creating apparatus for a power system according to any one of claims 1 to 6, further comprising a confirmation unit that confirms that a difference in stability limit power flow with respect to the original system model is less than or equal to zero. A computer or electronic circuit
A reduced model creation process for creating a reduced system model from an original power system model,
A control system constant tuning process for adjusting the control system constant of the reduced system model;
Run
The control system constant tuning process is:
Tidal current section data setting processing for setting a plurality of tidal current section data;
An assumed accident case setting process for setting a plurality of assumed accident cases;
Based on the tidal current cross-sectional data and the assumed accident case, the main system stability limit tidal current calculation process for calculating the stability limit tidal current of the original system model,
Based on the tidal current cross-sectional data, the accident sequence, and the control system constant, a reduced system stability limit tidal current calculation process for calculating a stable limit tidal current of the reduced system model,
A difference calculation process for calculating a difference between the stability limit current of the reduced system model and the stability limit current of the original system model;
Based on the difference, a constant estimation process for estimating a control system constant at which the stability limit power of the reduced system model is equal to or less than the stability limit power of the original system model;
A constant output process for outputting the control system constant estimated by the constant estimation unit;
A method for creating a reduced model of an electric power system, comprising: On the computer,
A reduced model creation process for creating a reduced system model from an original power system model,
A control system constant tuning process for adjusting the control system constant of the reduced system model;
And execute
The control system constant tuning process is:
Tidal current section data setting processing for setting a plurality of tidal current section data;
An assumed accident case setting process for setting a plurality of assumed accident cases;
Based on the tidal current cross-sectional data and the assumed accident case, the main system stability limit tidal current calculation process for calculating the stability limit tidal current of the original system model,
Based on the tidal current cross-sectional data, the accident sequence, and the control system constant, a reduced system stability limit tidal current calculation process for calculating a stable limit tidal current of the reduced system model,
A difference calculation process for calculating a difference between the stability limit current of the reduced system model and the stability limit current of the original system model;
Based on the difference, a constant estimation process for estimating a control system constant at which the stability limit power of the reduced system model is equal to or less than the stability limit power of the original system model;
A constant output process for outputting the control system constant estimated by the constant estimation unit;
A reduced model creation program for an electric power system characterized by including:

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