WO2024089997A1

WO2024089997A1 - Future system snapshot creation system and future system snapshot creation method

Info

Publication number: WO2024089997A1
Application number: PCT/JP2023/030595
Authority: WO
Inventors: 秀岳今井; 健太桐原; 英佑黒田; 雅浩渡辺
Original assignee: 株式会社日立製作所
Priority date: 2022-10-24
Filing date: 2023-08-24
Publication date: 2024-05-02

Abstract

This future system snapshot creation system comprises: an initial value calculation unit that uses supply and demand data, system configuration data, a voltage profile, a power flow calculation condition, and power generator parameters to calculate an initial setting value of a reactive power resource introduction amount that is the introduction amount of a reactive power resource; an optimal power flow calculation unit that uses the initial setting value calculated by the initial value calculation unit to perform optimal power flow calculation; and an adjustment unit uses the calculation result of the optimal power flow calculation unit to modify the initial setting value and create the future snapshot of a power system.

Description

Future system cross section creation system, future system cross section creation method

The present invention relates to a system for creating a future system cross section and a method for creating a future system cross section.

　Power grids are made up of generators, power transmission and distribution equipment, consumers, etc., and are known to be influenced by many factors. Traditionally, designs and plans were based on certain scenarios, but in recent years, with the introduction of new equipment such as renewable energy sources, plans are required to be more multifaceted. In order to create multifaceted plans, it is necessary to take into account multiple future scenarios. When verifying future scenarios, it is necessary to evaluate future snapshots that allocate demand by time period and region, etc. Patent Document 1 discloses a power generation plan determination system including: a power generation demand forecast value determination unit that determines a power generation demand forecast value, which is a forecast value of the amount of power required for the generator, based on a demand forecast value in a power system facility to which multiple renewable energy power sources and multiple generators are connected, and an output forecast value, which is a forecast value of the amount of power output by the renewable energy power sources; an initial power generation plan determination unit that determines an initial power generation plan for the generator based on the power generation demand forecast value determined by the power generation demand forecast value determination unit; an output fluctuation pattern creation unit that creates multiple output fluctuation patterns of the output forecast value based on the output forecast value and multiple variable output forecast values having different occurrence probabilities; and an optimal power generation plan determination unit that derives the transient stability of the power system facility predicted after the expected accident based on information about the expected accident and the multiple output fluctuation patterns created by the output fluctuation pattern creation unit, and determines an optimal power generation plan that can maintain the transient stability in the output fluctuation pattern based on the derived transient stability.

Japanese Patent Publication No. 2020-65368

The invention described in Patent Document 1 does not allow for appropriate reactive power setting.

A future power system cross section creation system according to a first aspect of the present invention includes an initial value calculation unit that calculates an initial setting value of a reactive power resource introduction amount, which is the amount of reactive power resource introduction, using supply and demand data, system configuration data, a voltage profile, power flow calculation conditions, and generator parameters, an optimal power flow calculation unit that performs an optimal power flow calculation using the initial setting value calculated by the initial value calculation unit, and an adjustment unit that modifies the initial setting value using a calculation result of the optimal power flow calculation unit and creates a future cross section of the power system.
A future system cross section creation method according to a second aspect of the present invention is a future system cross section creation method executed by a computer, and includes an initial value calculation process that calculates an initial setting value of a reactive power resource introduction amount, which is the amount of reactive power resources to be introduced, using supply and demand data, system configuration data, a voltage profile, power flow calculation conditions, and generator parameters, an optimal power flow calculation process that performs an optimal power flow calculation using the initial setting value calculated by the initial value calculation process, and an adjustment process that modifies the initial setting value using a calculation result of the optimal power flow calculation process to create a future cross section of the power system.

According to the present invention, future cross sections can be created by setting appropriate reactive power.

Power system configuration diagram Diagram of the future cross-section creation system Functional configuration diagram of a calculation unit in the first embodiment FIG. 1 is a diagram showing an example of a supply DB. FIG. 1 is a diagram showing an example of a system configuration DB. FIG. 1 is a diagram showing an example of a generator parameter DB. FIG. 1 is a diagram showing an example of a voltage profile DB; FIG. 13 is a diagram showing an example of a power flow calculation condition DB. FIG. 2 is a diagram showing an example of a reactive power resource introduction amount DB; FIG. 2 is a diagram showing an example of a reactive power resource schedule DB; 1 is a flowchart showing a process of an initial value calculation unit according to the first embodiment. Flowchart showing the process of the optimal power flow calculation unit Flowchart showing the process of the adjustment unit FIG. 13 is a diagram showing an example of a display screen displayed on a display unit. Functional configuration diagram of a calculation unit in the second embodiment 11 is a flowchart showing the process of the initial value calculation unit in the second embodiment.

-First embodiment-
A first embodiment of the future cross section creation system will be described below with reference to Figures 1 to 14. Note that the following is merely one embodiment, and it is not intended that the invention itself be limited to the specific content described below.

<Power system configuration>
1 is a configuration diagram of a power system 1 targeted by the future cross-section creation system. The power system 1 is composed of a generator 10, a load 14, and a photovoltaic power generation 15, which are connected via a branch (line) 12, a node (bus) 11, and a transformer 13, respectively, and a phase modifying equipment 16 connected to the bus. Reactive power resources include the tap position of the transformer 13, the reactive power output of the generator 10 and the photovoltaic power generation 15, the reactive power consumed and generated by the load 14, the phase modifying equipment 16, and the like.

The phase correcting equipment 16 includes a power capacitor (SC: Shunt Capacitor), a shunt reactor, a static voltage compensator, and a synchronous coder (SC: Synchronous Coder). Although not shown in FIG. 1, resources related to reactive power such as storage batteries are also included as reactive power resources. In this embodiment, the main purpose is to set the state and introduction amount of the phase correcting equipment 16, and these calculations are performed by the future cross-section creation system 100.

<Configuration of the future cross-section creation system>
2 is a configuration diagram of a future cross section creation system 100 according to a first embodiment of the present invention. The future cross section creation system 100 includes one or more computer systems, and is equipped with a display unit 101, an input unit 102, a communication unit 103, a processor 104, a memory 105, and a plurality of databases described below. Each of these devices that configure the future cross section creation system 100 is connected to a bus 106, and transmits and receives information using this bus 106. Hereinafter, the processor 104 and the memory 105 are collectively referred to as a calculation unit 110.

The display unit 101 is, for example, a display device. The display unit 101 may be configured to use a printer device, an audio output device, or the like instead of or together with the display device. The input unit 102 is configured to include, for example, at least one of a keyboard switch, a pointing device such as a mouse, a touch panel, an audio instruction device, and the like. The communication unit 103 includes a line connection method and a communication protocol for communicating with the future cross-section creation system 100.

The processor 104 executes calculation programs to instruct image data to be displayed and to search for data in various databases. The processor 104 may be configured as one or more semiconductor chips, or may be configured as a computer device such as a calculation server. The memory 105 is configured, for example, with a RAM (Random Access Memory) and a ROM (Read Only Member). For example, computer programs are stored in the ROM, and calculation result data, image data, processing programs, etc. required for each process are temporarily stored in the RAM. Also, for example, screen data stored in the memory 105 is sent to the display unit 101 and displayed.

The future cross section creation system 100 comprises multiple databases (hereinafter referred to as "DBs") as described below. That is, the future cross section creation system 100 comprises a program DB 41, a supply and demand DB 42, a system configuration DB 43, a generator parameter DB 44, a voltage profile DB 45, a power flow calculation condition DB 46, a reactive power resource introduction amount DB 47, and a reactive power resource schedule DB 48. Data is stored in advance in the program DB 41, the supply and demand DB 42, the system configuration DB 43, the generator parameter DB 44, the voltage profile DB 45, and the power flow calculation condition DB 46. Data is added to the reactive power resource introduction amount DB 47 and the reactive power resource schedule DB 48 by the process described below. Details of these databases will be described later.

<Functional configuration of the calculation unit>
3 is a functional configuration diagram of the calculation unit 110. The calculation unit 110 has, as its functions, an initial value calculation unit 111, an optimal power flow calculation unit 112, and an adjustment unit 113. These functions are realized by the processor 104 executing a program read from the program DB 41 to the memory 105. The calculation unit 110 obtains data required for calculation from the supply and demand DB 42, the system configuration DB 43, the generator parameter DB 44, the voltage profile DB 45, and the power flow calculation condition DB 46. Then, the calculation results of the initial value calculation unit 111, the optimal power flow calculation unit 112, and the adjustment unit 113 are stored in the reactive power resource introduction amount DB 47 and the reactive power resource schedule DB 48 via the bus 106.

<Database>
The program DB 41 stores programs for implementing the initial value calculation unit 111, the optimal power flow calculation unit 112, and the adjustment unit 113 that constitute the calculation unit 110.

FIG. 4 is a diagram showing an example of the supply and demand DB 42. The supply and demand DB 42 stores the supply amount of each power source for each section and the demand amount for each load. In the example shown in FIG. 4, the section is every hour, but the time interval can be any interval.

FIG. 5 is a diagram showing an example of the system configuration DB 43. The system configuration DB 43 stores parameters for each transmission line. Specifically, for each transmission line name, the sending end, receiving end, impedance, upper and lower limits of current and voltage, etc. are recorded. The system configuration DB 43 is used for power flow calculations, as described below. Note that while FIG. 5 shows a bus branch model that omits circuit breakers, it may also be configured as a node breaker model that includes circuit breakers, etc.

FIG. 6 is a diagram showing an example of the generator parameter DB 44. The generator parameter DB 44 stores parameters for each generator, specifically, rated capacity, minimum output, rated power factor, power factor limit, etc. In addition to the parameters shown in FIG. 6, parameters related to the ramp rate, continuous start time, or dynamic characteristics of the generator may also be stored.

FIG. 7 shows an example of the voltage profile DB 45. The voltage profile DB 45 stores the target voltage for each cross section and each busbar.

Figure 8 is a diagram showing an example of the power flow calculation condition DB 46. The power flow calculation condition DB 46 stores the power flow calculation conditions for each bus. Specifically, for each bus and for each type, the power flow calculation condition stored is either PV-specified, PQ-specified, or Vδ-specified. The power flow calculation conditions can be set separately for the first time and for subsequent times. Here, the first time power flow calculation refers to the power flow calculation performed by the initial value calculation unit 111, and the power flow calculations from the first time onwards refer to the optimal power flow calculation and power flow calculation in the optimal power flow calculation unit 112 and the adjustment unit 113.

FIG. 9 is a diagram showing an example of reactive power resource introduction amount DB47. Reactive power resource introduction amount DB47 stores the introduction amount of reactive power resources for each bus. For example, among reactive power resources, the equipment capacities of SC and ShR are stored as the introduction amount of phase modifying equipment for each bus.

FIG. 10 is a diagram showing an example of reactive power resource schedule DB48. Reactive power resource schedule DB48 stores the parallel amount of adjustment equipment on the bus, the transformer tap, the reactive power output, etc. for each cross-section time for each bus and for each time, and by utilizing this data, an appropriate power flow cross-section can be created, making it possible to evaluate future stability scenarios. However, it is not essential to use all three of the parallel amount of adjustment equipment, the transformer tap, and the reactive power output as reactive power resources, and it is sufficient to use at least one of them.

<Calculation section>
The initial value calculation unit 111 receives the supply and demand data stored in the supply and demand DB 42, the system information stored in the system configuration DB 43, the generator parameters stored in the generator parameter DB 44, the reference voltage stored in the voltage profile DB 45, and the system constraints stored in the power flow calculation condition DB 46, and calculates an initial setting value of the amount of phase modifying equipment introduction. The initial value calculation unit 111 then outputs the calculated initial setting value of the amount of phase modifying equipment introduction to the optimal power flow calculation unit 112. The optimal power flow calculation unit 112 receives the initial setting value of the amount of phase modifying equipment introduction calculated by the initial value calculation unit 111, the supply and demand data stored in the supply and demand DB 42, the system information stored in the system configuration DB 43, the generator parameters stored in the generator parameter DB 44, and the power flow calculation condition DB 46, and creates time series data of a future system cross section. The optimal power flow calculation unit 112 then outputs the created time series data of the future system cross section to the adjustment unit 113.

The adjustment unit 113 receives as input the initial setting value of the amount of phase modifying equipment introduction calculated by the initial value calculation unit 111 and the time series data of the future system cross section created by the optimal power flow calculation unit 112, and calculates the amount of phase modifying equipment introduction, the amount of phase modifying equipment in parallel, the transformer tap position, and the generator reactive power output.The adjustment unit 113 then sends the calculated amount of phase modifying equipment introduction, the amount of phase modifying equipment in parallel, the transformer tap position, and the generator reactive power output to the reactive power resource introduction amount DB47 and the reactive power resource schedule DB48.The processing of each component of the calculation unit 110 will be described below with reference to a flowchart.

FIG. 11 is a flowchart showing the processing of the initial value calculation unit 111. First, in step S100, the initial value calculation unit 111 sets constraint conditions for the power flow calculation and proceeds to step S101. Specifically, the initial value calculation unit 111 reads the upper and lower limit values of the voltage and current of each transmission line to be calculated from the system configuration DB 43. In step S101, the initial value calculation unit 111 initializes the variable time T to "1" and proceeds to step S102.

In step S102, the initial value calculation unit 111 sets the power flow calculation conditions. Specifically, the initial value calculation unit 111 obtains supply and demand data from the supply and demand DB 42 and a voltage profile from the voltage profile DB 45, and sets the power flow calculation conditions for each busbar in the target cross section. For example, for a busbar designated as PV, an active power designation value is set from the supply and demand data, and a voltage designation value is set from the voltage profile. Generally, one of PV designation, PQ designation, and Vδ (slack busbar) designation is set, and a busbar in which a phase modifying equipment is introduced is set to PV designation, so that the amount of reactive power injection required to achieve the set voltage designation can be calculated, and the amount of phase modifying equipment to be introduced can be estimated from the reactive power amount.

In step S103, the power flow calculation is executed. In step S104, the power flow calculation is judged to have converged. If convergence is confirmed, the process proceeds to step S105. If not, the process proceeds to step S106. The initial value calculation unit 111 can judge whether the power flow calculation has converged, for example, by checking whether the difference in output for each loop is equal to or less than a predetermined value. In step S105, the initial value calculation unit 111 judges whether the result of the power flow calculation in step S103 satisfies the voltage and current constraint conditions. Specifically, the initial value calculation unit 111 judges whether the voltage is between a predetermined lower limit and an upper limit, and the current is between a predetermined lower limit and an upper limit, in the result of the power flow calculation. These voltage and current conditions are written in the system configuration DB 43. If the initial value calculation unit 111 judges that the result of the power flow calculation satisfies the constraint conditions, the process proceeds to step S107. If the initial value calculation unit 111 judges that the result of the power flow calculation satisfies the constraint conditions, the process proceeds to step S106.

In step S106, the initial value calculation unit 111 modifies the conditions for the power flow calculation and returns to step S103. Specifically, the initial value calculation unit 111 calculates the evaluation value α for all sections in which the calculation conditions for the busbars at both ends are PV specified, using the following formula 1.

α＝｜V(1)-V(2)｜/｜Z(12)｜ …(Equation 1)

Here, V(1) and V(2) are the designated voltage values of each bus at time T, and Z(12) is the impedance of the transmission line connecting the buses. The designated voltage values of each bus at each time are stored in the voltage profile DB45. The impedance of each transmission line is stored in the system configuration DB43. The initial value calculation unit 111 then changes one of the buses in the section with the lowest evaluation value α from PV designated to PQ designated. Note that the value of Q in this case is a value that is predetermined for each section.

The significance of the processing in this step is as follows. The power flow calculation used in power system analysis generally involves a calculation to minimize the difference between the power flowing into the bus and the power flowing out of the bus from the initial point, as in the Newton-Raphson method. The Jacobian matrix used in this calculation process is calculated using the transmission line impedance between the buses, and is generally used to solve simultaneous equations using LU decomposition, etc. In this case, if the transmission line impedance between the PV-designated buses is smaller than the others in the modeling, the Jacobian matrix elements may approximate 0, and the Jacobian matrix may become a singular matrix. In this case, there is a concern that the simultaneous equations will not be solved and the calculations will not converge. Therefore, for points where the buses at both ends are PV-designated, an index α that indicates the convergence of the power flow calculation is calculated, and points where convergence is unlikely to occur are changed from PV-designated to PQ-designated, making it easier to converge.

In step S107, the initial value calculation unit 111 records the reactive power injection amount of the busbar connected to the phase modifying equipment based on the result of the power flow calculation for the target time section. In the following step S108, the initial value calculation unit 111 judges whether the time T is greater than a predetermined time T_MAX, that is, whether the calculation for a predetermined time has been completed. If the initial value calculation unit 111 judges that the time T is greater than the predetermined time T_MAX, the process proceeds to step S110, and if the initial value calculation unit 111 judges that the time T is equal to or less than the predetermined time T_MAX, the process proceeds to step S109. In step S109, the initial value calculation unit 111 updates the time T to a number that is "1" greater, and returns to step S102. In step S110, the initial value calculation unit 111 sets the initial value of the amount of phase modifying equipment introduction based on the result of the power flow calculation, and ends the process shown in FIG. 11.

FIG. 12 is a flowchart showing the processing of the optimal power flow calculation unit 112. First, in step S200, the optimal power flow calculation unit 112 sets an objective function for the optimal power flow calculation. This objective function is used in the optimal power flow calculation in step S203, which will be described later. For example, when implementing the operation of voltage and reactive power control, the objective function can be set to at least one of minimizing active power loss, minimizing reactive power loss, and minimizing the number of times the phase modifying equipment operates. In the following step S201, the optimal power flow calculation unit 112 sets constraint conditions for the optimal power flow calculation. These constraint conditions are the upper and lower limits of the voltage and current of each transmission line stored in the system configuration DB 43, and the amount of phase modifying equipment introduced calculated by the initial value calculation unit 111.

In the following step S202, the variable time T is initialized to "1" and the process proceeds to step S203. In step S203, the optimal power flow calculation unit 112 executes the optimal power flow calculation. Specifically, the optimal power flow calculation unit 112 performs the optimal power flow calculation according to the objective function of the optimal power flow calculation set in step S200 and the constraint conditions of the optimal power flow calculation set in step S201. For example, explanatory variables when implementing the operation of voltage reactive power control are the voltage of each bus, the parallel amount of phase modifying equipment, the transformer tap position, and the generator reactive power output or voltage specified value.

In the following step S204, the optimal power flow calculation unit 112 records the results of the optimal power flow calculation. In the following step S205, it is determined whether time T is greater than a predetermined time T_MAX, i.e., whether the calculation for a predetermined period of time has been completed. If the optimal power flow calculation unit 112 determines that time T is greater than the predetermined time T_MAX, it ends the process shown in FIG. 12, and if it determines that time T is equal to or less than the predetermined time T_MAX, it proceeds to step S206. In step S206, the optimal power flow calculation unit 112 updates time T to a number that is "1" greater, and returns to step S203.

In the explanation of FIG. 12, voltage reactive power control was given as an example of an optimal power flow calculation, but load frequency control may also be implemented. Furthermore, the objective function of voltage reactive power control is not limited to the above example, and may be reactive power loss minimization, or an objective function may be defined by combining multiple objectives.

FIG. 13 is a flowchart showing the processing of the adjustment unit 113. The adjustment unit 113 first judges whether the constraint condition is satisfied in step S300, and ends the processing shown in FIG. 13 if it judges that the constraint condition is satisfied, and proceeds to step S301 if it judges that the constraint condition is not satisfied. Specifically, the adjustment unit 113 judges whether the calculation result by the optimal power flow calculation unit 112 satisfies the upper and lower limit conditions of the voltage and current of each transmission line stored in the system configuration DB 43. The adjustment unit 113 judges that the constraint condition is satisfied when the voltage is equal to or greater than the lower limit and equal to or less than the upper limit, and further the current is equal to or greater than the lower limit and equal to or less than the upper limit, for all transmission lines subject to calculation, and judges that the constraint condition is not satisfied when the voltage is less than the lower limit or greater than the upper limit, or the current is less than the lower limit or greater than the upper limit, for one or more transmission lines subject to calculation.

In step S301, the adjustment unit 113 extracts sections that deviate from the constraint conditions, i.e., violation sections, from the results of the optimal power flow calculation. In step S302, the adjustment unit 113 corrects the amount of phase modifying equipment introduced. Specifically, the adjustment unit 113 corrects the amount of phase modifying equipment introduced for the violation sections extracted in step S301. For this correction, for example, the minimum amount of phase modifying equipment correction can be calculated by using an optimization problem of the amount of phase modifying equipment correction using the sensitivity to the violation node calculated during the power flow calculation process. Specifically, the objective function shown in Equation 2 and the constraint condition shown in Equation 3 are used.

Here, ΔQ _i is the phase modifying equipment correction amount of node i, LV _i is the lower limit voltage value of node i, UV _i is the upper limit voltage value of node i, and α _i is the voltage sensitivity to the reactive power of node i obtained in the process of power flow calculation. In the above optimization problem, the upper limit voltage value of each node is set as a constraint condition, and a quadratic function of the change in the phase modifying equipment correction amount is set as the objective function, so that the minimum phase modifying equipment introduction amount that eliminates the constraint deviation can be calculated. Note that, in order to obtain a solution to this optimization problem, an optimization method such as quadratic programming may be applied.

In step S303, the adjustment unit 113 initializes the variable time T to "1" and proceeds to step S304. In step S304, the adjustment unit 113 performs an optimal power flow calculation at time T. In the following step S305, the adjustment unit 113 records the result of the optimal power flow calculation in step S304. In step S306, the adjustment unit 113 determines whether time T is greater than a predetermined time T_MAX, that is, whether calculation for a predetermined period of time has been completed. If the adjustment unit 113 determines that time T is greater than the predetermined time T_MAX, the adjustment unit 113 proceeds to step S308, and if the adjustment unit 113 determines that time T is equal to or less than the predetermined time T_MAX, the adjustment unit 113 proceeds to step S307. In step S307, the adjustment unit 113 updates time T to a number that is "1" greater and returns to step S304.

In step S308, the adjustment unit 113 determines whether the calculation result in step S304 satisfies the constraint conditions. The processing in this step is the same as step S300 except for the evaluation target. If the adjustment unit 113 determines that the calculation result in step S304 satisfies the constraint conditions, the adjustment unit 113 proceeds to step S309, and if the calculation result in step S304 does not satisfy the constraint conditions, the adjustment unit 113 returns to step S301. In step S309, the adjustment unit 113 records the amount of phase modifying equipment introduction in the power flow calculation result, and ends the processing shown in FIG. 13.

<Display section>
FIG. 14 is a diagram showing an example of a display screen 101A displayed on the display unit 101. A combination of the reactive power resource introduction amount stored in the reactive power resource introduction amount DB 47 and the system configuration stored in the system configuration DB 43 is displayed in the upper part of the display screen 101A. In FIG. 14, the introduction amount of the phase modifying equipment is shown as the reactive power resource, but in addition, the upper and lower limit values of the reactive power of the generator and the tap width of the transformer tap may be shown. In the lower part of FIG. 14, a schedule of the reactive power resource is displayed in a graph. In FIG. 14, the parallel amount of the phase modifying equipment, the transformer tap position, and the generator reactive power output are shown as the reactive power resource, but are not limited to these. In addition, the upper limit value of the reactive power supply amount may be added to these graphs.

According to the above-described first embodiment, the following advantageous effects can be obtained.
(1) The future cross-section creation system 100 includes an initial value calculation unit 111 that calculates an initial setting value of a reactive power resource introduction amount, which is an introduction amount of reactive power resources, using a supply and demand DB 42, a system configuration DB 43, a voltage profile DB 45, a power flow calculation condition DB 46, and a generator parameter DB 44, an optimal power flow calculation unit 112 that performs an optimal power flow calculation using the initial setting value calculated by the initial value calculation unit 111, and an adjustment unit 113 that modifies the initial setting value using a calculation result of the optimal power flow calculation unit 112 and creates a future cross-section of the power system. Therefore, a future cross-section can be created by setting an appropriate reactive power. Specifically, this is as follows.

The initial value calculation unit 111 can calculate the initial introduction amount of phase modifying equipment by specifying PV as the power flow calculation condition for the busbar for which the introduction amount of phase modifying equipment is to be calculated. In addition, after a future cross section is created by the optimal power flow calculation unit 112 using the initial introduction cost of the phase modifying equipment calculated by the initial value calculation unit 111 as a constraint condition, if there is a violation in the results of the optimal power flow calculation unit 112, the adjustment unit 113 can calculate the introduction amount of phase modifying equipment and its schedule that does not cause a voltage violation by adjusting the introduction amount of the phase modifying equipment. This makes it possible to create a system cross section that allows the system stability to be appropriately evaluated.

(2) In step S106 of FIG. 11, the initial value calculation unit 111 calculates an index α, which indicates the convergence of the power flow calculation, for each section using the power flow calculation conditions, and modifies the power flow calculation conditions for the section with the lowest index α. As a result, the accuracy of the calculation results decreases, but the convergence can be improved.

(3) In order to implement voltage and reactive power control as an optimal power flow calculation, the optimal power flow calculation unit 112 sets at least one of minimizing active power loss, minimizing reactive power loss, and minimizing tap operation as an objective function. Therefore, the objective function can be changed as appropriate.

(4) In step S302 of FIG. 13, the adjustment unit 113 uses a reactive power resource introduction amount minimization problem using sensitivity coefficients for violating nodes generated during the power flow calculation process as a method for correcting the initial setting values. Therefore, it is possible to appropriately set the initial setting values of violating nodes that do not satisfy the constraint conditions.

(5) Targeting phase modifying equipment as a reactive power resource, an initial value calculation unit 111 calculates the initial introduction amount of the phase modifying equipment, an optimal power flow calculation unit 112 calculates the parallel amount of the phase modifying equipment, and an adjustment unit 113 corrects the introduction amount of the phase modifying equipment and recalculates the parallel amount.

(6) The transformer tap is targeted as the reactive power resource, and the optimal power flow calculation unit 112 calculates the tap position of the transformer, and the adjustment unit 113 recalculates the tap position.

(7) The generator is targeted as the reactive power resource, and the optimal power flow calculation unit 112 calculates the reactive power output of the generator, and the adjustment unit 113 recalculates the reactive power output.

(Variation 1)
In the first embodiment, the reactive power resources are exemplified by a phase modifying facility, a transformer tap, and a generator reactive power output. However, other reactive power resources such as a storage battery and a static synchronous compensator (STATCOM) may be used.

(Variation 2)
The initial value calculation unit 111 corrected the power flow calculation conditions in the section with the smallest evaluation value α in step S106 in Fig. 11. However, the initial value calculation unit 111 may change the power flow calculation conditions in two or more sections in step S106. For example, the initial value calculation unit 111 may change the power flow calculation conditions in the section with the smallest evaluation value α and the section with the second smallest evaluation value α.

--Second embodiment--
A second embodiment of the future cross section creation system will be described with reference to Figures 15 and 16. In the following description, the same components as in the first embodiment are given the same reference numerals, and differences will be mainly described. Points that are not specifically described are the same as in the first embodiment. This embodiment differs from the first embodiment mainly in that supply and demand data is organized into similar scenarios by clustering.

FIG. 15 is a functional configuration diagram of the calculation unit 110a in the second embodiment. The difference from the functional configuration shown in FIG. 3 in the first embodiment is that an initial value calculation unit 111a is provided instead of the initial value calculation unit 111. The operation of the optimal power flow calculation unit 112 and the adjustment unit 113 is the same as in the first embodiment, so a description thereof will be omitted.

FIG. 16 is a flowchart showing the processing of the initial value calculation unit 111a in the second embodiment. The difference from the processing shown in FIG. 11 in the first embodiment is that steps S111 and S112 are provided instead of step S101, step S113 is provided instead of step S108, and step S114 is provided instead of step S109. The operation of the other processing steps is the same as in the first embodiment, so a description thereof will be omitted.

In step S111, the initial value calculation unit 111a clusters the supply and demand data. Clustering methods that can be used include DBSCAN (Density-based spatial clustering of applications with noise) and the k-means method. In this clustering, similar scenarios are identified by clustering the supply and demand data using demand, thermal power generation, and renewable energy power generation as evaluation indicators. In the following step S112, the initial value calculation unit 111a sets a representative cross section of the cluster as the target cross section. The initial value calculation unit 111a may set the average value of each cluster as the representative cross section, or may set the median value as the representative cross section.

In step S113, the initial value calculation unit 111a determines whether or not the power flow calculation has been completed for all representative cross sections. If the initial value calculation unit 111a determines that the power flow calculation has been completed for all representative cross sections, it proceeds to step S110, and if it determines that there is a representative cross section for which the power flow calculation has not been completed, it proceeds to step S114. In step S114, the initial value calculation unit 111a sets another representative cross section for which the power flow calculation has not been completed as the target cross section, and returns to step S102.

According to the above-described second embodiment, the following advantageous effects can be obtained.
(8) The initial value calculation unit 111a clusters the supply and demand data using the feature quantities of the supply and demand data, and calculates the initial setting values using the representative cross section of each cluster. Therefore, since the power flow calculation is performed for the representative cross section of each cluster, the calculation can be completed in a shorter time than in the first embodiment.

In each of the above-mentioned embodiments and variations, the functional block configurations are merely examples. Several functional configurations shown as separate functional blocks may be configured together, or a configuration shown in a single functional block diagram may be divided into two or more functions. In addition, some of the functions of each functional block may be provided by other functional blocks.

In each of the above-mentioned embodiments and variations, the programs are stored in the program DB 41, but in the future the cross-section creation system 100 may be equipped with an input/output interface (not shown), and the programs may be read from other devices via the input/output interface when necessary. Here, the medium refers to, for example, a storage medium that is detachable from the input/output interface, or a communication medium, i.e., a network such as a wired, wireless, or optical network, or a carrier wave or digital signal that propagates through the network. In addition, some or all of the functions realized by the programs may be realized by a hardware circuit or FPGA.

The above-mentioned embodiments and modifications may be combined with each other. Although various embodiments and modifications have been described above, the present invention is not limited to these. Other aspects that are conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention.

111, 111a: Initial value calculation unit 112: Optimal power flow calculation unit 113: Adjustment unit 42: Supply and demand DB
43: System configuration DB
44: Generator parameter DB
45: Voltage profile DB
46: Power flow calculation condition DB
47: Reactive power resource introduction amount DB
48: Reactive power resource schedule DB
α : Evaluation value

Claims

an initial value calculation unit that calculates an initial setting value of a reactive power resource introduction amount, which is an introduction amount of reactive power resources, by using supply and demand data, system configuration data, a voltage profile, a power flow calculation condition, and a generator parameter;
an optimal power flow calculation unit that performs an optimal power flow calculation using the initial setting value calculated by the initial value calculation unit;
and an adjustment unit that uses a calculation result of the optimal power flow calculation unit to correct the initial setting value and create a future cross section of the power system.
The future system cross section creation system according to claim 1,
a power flow calculation condition calculation unit that calculates an index representing convergence of the power flow calculation for each section using the power flow calculation conditions, and corrects at least the power flow calculation condition for the section in which the index is the lowest.
The future system cross section creation system according to claim 1,
The optimal power flow calculation unit is
A future power system cross section creation system that uses at least one of minimizing active power loss, minimizing reactive power loss, and minimizing tap operation as an objective function in order to implement voltage and reactive power control as an optimal power flow calculation.
The future system cross section creation system according to claim 1,
A future system cross-section creation system, wherein the adjustment unit uses a reactive power resource introduction minimization problem using a sensitivity coefficient for a violation node generated during a power flow calculation as a method for correcting the initial setting value.
The future system cross section creation system according to claim 1,
The reactive power resource is a phase modifying device,
The initial value calculation unit calculates an initial introduction amount of the phase modifying equipment,
The optimal power flow calculation unit calculates the amount of parallel operation of the phase modifying equipment,
The adjustment unit corrects the amount of phase modifying equipment introduced and recalculates the amount of paralleling, in a future system cross-section creation system.
The future system cross section creation system according to claim 1,
The reactive power resource is a transformer tap;
The optimal power flow calculation unit calculates a tap position of a transformer,
The adjustment unit recalculates the tap position.
The future system cross section creation system according to claim 1,
The reactive power resource is a generator,
The optimal power flow calculation unit calculates a reactive power output of a generator,
The adjustment unit recalculates the reactive power output.
The future system cross section creation system according to claim 1,
The initial value calculation unit clusters the supply and demand data using a feature of the supply and demand data, and calculates the initial setting value using a representative cross section for each cluster.
A method for creating a future system cross section executed by a computer, comprising the steps of:
An initial value calculation process of calculating an initial setting value of a reactive power resource introduction amount, which is an introduction amount of reactive power resources, using supply and demand data, system configuration data, a voltage profile, a power flow calculation condition, and a generator parameter;
an optimal power flow calculation process for performing an optimal power flow calculation using the initial setting values calculated by the initial value calculation process;
and an adjustment process for correcting the initial setting value using a calculation result from the optimal power flow calculation process, and creating a future cross section of the power system.