State Estimation Device, Control Method of State Estimation Device, and Program

Abstract

To estimate a state of a distribution system even when the number of measuring instruments is less than the number of positions (estimation point) to be estimated in the distribution system.SOLUTION: A state estimation device for determining a state of a section constituting a plurality of nodes in a distribution system, includes: a measurement value acquiring section which acquires a tide measurement value at an end part of the section and an effective power measurement value at the plurality of nodes; a distribution coefficient acquisition section which acquires a distribution coefficient showing a proportion of reactive power at the plurality of nodes; and a state estimation section which determines a total value of reactive power in the section and effective power at the plurality of nodes as a state of the section by converting a total value of reactive power in the section into reactive power at the plurality of nodes, using the distribution coefficient to input the tide measurement value and the effective power measurement value into a first equation form constituted to estimate the state of the section.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a state estimation device, a control method for the state estimation device, and a program.

Background Art

[0002] For example, a technique for estimating the state of a power distribution system based on measured system information is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, it may be difficult to uniquely determine the state value of a point to be estimated (estimation point) based on measurement data, such as when the number of measuring instruments is smaller than the number of points to be estimated (estimation points) in the power distribution system.

[0005] The present invention has been made in view of such problems, and an object of the present invention is to provide a state estimation device, a control method for the state estimation device, and a program that enable estimation of the state of a power distribution system even when the number of measuring instruments is smaller than the number of points to be estimated (estimation points) in the power distribution system.

Means for Solving the Problems

[0006] One aspect for solving the above-described problems is a state estimation device that obtains the state of a section configured to have a plurality of nodes in a power distribution system, the measurement value acquisition unit acquiring a power flow measurement value at an end of the section and an active power measurement value at the plurality of nodes, a distribution coefficient acquisition unit acquiring a distribution coefficient representing a ratio of reactive power at the plurality of nodes, and a first equation configured to be able to estimate the state of the section by converting the total value of reactive power in the section into reactive power at the plurality of nodes using the distribution coefficient, and a state estimation unit that obtains the total value of reactive power in the section and the active power at the plurality of nodes as the state of the section by inputting the power flow measurement value and the active power measurement value into the first equation.

Advantages of the Invention

[0007] The present invention can estimate the state of a power distribution system even when the number of measuring devices is smaller than the number of locations (estimation points) where estimation is desired in the power distribution system.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0009] At least the following matters become clear from the description of this specification and the accompanying drawings. <<<Configuration of the State Estimation Device 200>>>

[0010] FIG. 1 is a diagram showing the configuration of a state estimation device 200 according to an embodiment of the present invention. The state estimation device 200 is a device that estimates the state of the power distribution system 1000 shown in FIGS. 3 to 5 and the like, and is a computer having a CPU (Central Processing Unit) 210, a memory 220, a communication device 230, a storage device 240, an input device 250, an output device 260, and a recording medium reader 270.

[0011] The CPU 210 realizes various functions of the state estimation device 200 by executing a state estimation device control program 700 stored in the memory 220 and the storage device 240.

[0012] The memory 220 is, for example, a RAM (Random-Access Memory) or the like, and is used as a temporary storage area for various programs, data, and the like.

[0013] The storage device 240 is a non-temporary (for example, non-volatile) storage device that stores various data to be executed or processed by the CPU 210.

[0014] FIG. 2 shows a state in which the state estimation device control program 700 and the system information table 600 are stored in the storage device 240.

[0015] By reading various data such as the state estimation device control program 700 and the system information table 600 stored in the storage device 240 into the memory 220 and executing or processing them by the CPU 210, various functions of the state estimation device 200 are realized.

[0016] The state estimation device control program 700 is a general term for programs for realizing the functions of the state estimation device 200 according to the present embodiment, and includes, for example, application programs, an OS (Operating System), and various libraries operating on the state estimation device 200.

[0017] The system information table 600 is a table that records the configuration of the power distribution system 1000 and the electrical characteristics of the devices that make up the power distribution system 1000.

[0018] The system information table 600 records, for example, the data necessary when simulating the power distribution system 1000 using equations such as state equations and power flow equations. Although details will be described later, the state estimator 200 uses the system information table 600 in a state where it has acquired the power flow measurement value of the switch SW with a sensor and the active power measurement value of the smart meter SM, and executes the state estimation process described in detail below. In the state estimation process, the state of the power distribution system 1000 starting from section K, that is, the state values such as voltage, current, and power in the power distribution system 1000 are obtained.

[0019] Returning to FIG. 1, the input device 250 is a device that accepts input of commands and data by the user, and includes input interfaces such as a keyboard and a touch sensor that detects the touch position on the touch panel display.

[0020] The output device 260 is a device such as a display or a printer.

[0021] The communication device 230 exchanges various programs and data with other computers via the network 500.

[0022] The recording medium reader 270 reads various data such as the state estimator control program 700 and the system information table 600 recorded on the recording medium 800 such as an SD card, a DVD, or a CD-ROM, and stores them in the storage device 240. <<<An example of the power distribution system 1000>>> FIGS. 3 to 5 are diagrams showing an example of the power distribution system 1000 in which the state estimator 200 performs state estimation. The power distribution system 1000 is, for example, a 6.6 kV high-voltage system, and includes a distribution substation 1100, a distribution line 1200, a switch SW with a sensor, and a smart meter SM.

[0023] The switch SW with sensors is arranged at the end of a section K of the power distribution system 1000. That is, the switch SW with sensors divides the power distribution system 1000 into a plurality of sections. The switch SW with sensors is a measuring instrument capable of measuring the voltage, current and phase at the measurement point (the end of section K), or the active power and reactive power. Hereinafter, the voltage, current and phase measured by the switch SW with sensors, or the active power and reactive power, are collectively referred to as "power flow measurement values" or "measurement values of power flow".

[0024] The smart meter SM is a measuring instrument capable of measuring the active power consumed by the consumers connected to the power distribution system 1000.

[0025] Each consumer becomes a power load. The consumers may include facilities (such as factories) that consume the power supplied from the distribution line 1200, and may also include power generation facilities (not shown) such as inverters that supply power to the distribution line 1200. Therefore, the distribution line 1200 is connected to facilities that consume the power from the distribution line 1200 and power generation facilities that supply power to the distribution line 1200. Here, regardless of the distinction between consumption and supply, they are collectively referred to as loads.

[0026] Also, a plurality of nodes N are provided in the section K of the power distribution system 1000. The node N represents each range obtained by further dividing the section K in finer detail, and is specified by an appropriately determined position on the power distribution system 1000, such as a transformer installed in the section K or a branch point of the distribution line 1200. In this embodiment, it is assumed that the smart meters SM of one or more consumers are aggregated at each node N in the section K.

[0027] Hereinafter, the active power measured by the smart meter SM and aggregated at each node N is collectively referred to as the "active power measurement value".

[0028] The distribution substation 1100 transforms the voltage supplied from a transmission line (not shown) and outputs a voltage of 6.6 kV to the distribution line 1200. The power is supplied to consumers (not shown) via the node N.

[0029] In addition, the power distribution system 1000 also includes various other facilities and sensors, etc. For the sake of convenience, a simplified power distribution system 1000 is illustrated here as an example.

[0030] For example, the power distribution system 1000 will be described with reference to the example in FIG. 4.

[0031] The power distribution system 1000 has a power distribution substation 1100 as the starting point (feeding node), and power distribution lines 1200 are radially connected. Sensored switches SW1 to SW5 are installed on the power distribution lines 1200, and the sections divided by these sensored switches SW1 to SW5 are defined as section K1 to section K4.

[0032] However, when a sensored switch SW is not installed on the end side of the power distribution system 1000 like section K4, the section from the sensored switch SW on the feeding side to the end node is defined as the section.

[0033] Also, nodes N are defined on the power distribution lines 1200. The node N is an aggregation unit managed in units of pole-mounted transformers or specified customer units. Measurement values from the smart meters SM of multiple customers are aggregated for each node N and used in state estimation.

[0034] In the sensored switches (SW1 to SW5), the voltage, current, and phase at the installation point are measured at a fixed period Ts1 (for example, 1 minute). These measurement values are stored in a database (for example, constructed in the storage device 240).

[0035] At this time, it is assumed that the active power flow and reactive power flow can be uniquely converted from the voltage, current, and phase. Hereinafter, the measurement values from the sensored switch SW are treated as voltage, active power flow, and reactive power flow.

[0036] In the smart meter SM, the power consumption (active power) of consumers is measured at regular intervals of Ts2 (for example, 30 minutes) for each node (N1 to N12). These measurement values are stored in a database (for example, constructed in the storage device 240).

[0037] Since the average value of the active power amount can be calculated by dividing the power consumption per period by the measurement period, the measurement values from the smart meter SM are treated as the average value of the active power. <<<Functional blocks of the information processing device>>>

[0038] FIG. 6 is a diagram showing the functional blocks of the state estimation device 200. The state estimation device 200 has the functions of a measurement value acquisition unit 201, a distribution coefficient acquisition unit 202, a state estimation unit 203, and a reactive power calculation unit 204.

[0039] Each of these functions is realized by the state estimation device control program 700 according to the present embodiment being executed by the hardware of the state estimation device 200.

[0040] The measurement value acquisition unit 201 acquires the power flow measurement value at the end of the section K of the power distribution system 1000 and the active power measurement values at a plurality of nodes N within the section K. As described above, in the present embodiment, the measurement value acquisition unit 201 acquires the power flow measurement value from the switch SW with a sensor every minute and the active power measurement value from the smart meter SM every 30 minutes.

[0041] The distribution coefficient acquisition unit 202 acquires distribution coefficients representing the ratios of reactive power at a plurality of nodes N within the section K. For example, the distribution coefficient acquisition unit 202 acquires the distribution coefficients by performing predetermined data analysis using both or one of data related to the facilities connected to these plurality of nodes N and past measurement data of reactive power at the plurality of nodes N. Details will be described later.

[0042] The state estimation unit 203 inputs the power flow measurement value and the active power measurement value into a first equation configured to be able to estimate the state of section K by converting the total value of reactive power in section K into reactive power at a plurality of nodes N using the distribution coefficient, thereby obtaining the total value of reactive power in section K and the active power at the plurality of nodes as the state of the section.

[0043] In such a manner, even when the number of measuring instruments is smaller than the number of points (estimation points) where estimation is to be performed in the distribution system 1000, the state estimation device 200 can estimate the state of the distribution system 1000.

[0044] For example, even if the reactive power of each node N within section K is unknown, if the total value of reactive power in section K is known, the state estimation unit 203 can input this into the first equation and solve it to estimate the state of section K.

[0045] Therefore, even when the reactive power of each node N within section K of the distribution system 1000 cannot be obtained, the state estimation device 200 can estimate the state of the distribution system 1000.

[0046] For example, when performing state estimation of the distribution system 1000, the state estimation device 200 does not set the elements of the state value as the active power and reactive power of each node N, but defines the active power of each node N and the total value of reactive power of the nodes within the specified section K. Therefore, the degree of freedom with respect to the number of elements of the measurement value is restricted, and the state value can be uniquely determined when performing state estimation.

[0047] Regarding the line loss of electric power, by treating the active power of each node N and the total value of reactive power of all nodes N in the specified section K as state values and performing the calculation of the measurement value using the first equation, it is possible to perform state estimation considering the line loss.

[0048] The reactive power calculation unit 204 calculates the reactive power at a plurality of nodes N within section K using the total value of reactive power in section K of the distribution system 1000 and the distribution coefficient.

[0049] In this case, the state estimation unit 203 may further calculate a predetermined second equation using the reactive power at a plurality of nodes N within the section K and the active power at the plurality of nodes within the section K, and estimate the state of the section K by calculating the voltage values at the plurality of nodes N.

[0050] According to such an aspect, the state estimation device 200 can estimate the state of a location (estimation point) in the power distribution system 1000 where estimation is to be performed.

[0051] A more detailed description will be given with reference to FIG. 3.

[0052] FIG. 3 shows a state estimation device 200 obtaining measurement values (power flow measurement values) at regular intervals (e.g., 1 minute) related to voltage, current, and phase from a switch SW with a sensor, obtaining measurement values (active power measurement values) at regular intervals (e.g., 30 minutes) related to power consumption from a smart meter SM, obtaining a system information table 600 (system facility data) stored in a database within a storage device 240, and performing a power flow calculation using a first equation to estimate, as the state of the power distribution system 1000, the active power value per node N defined in advance and the total reactive power of the nodes in a predefined section K (state estimation 1).

[0053] Further, the state estimation device 200 uses a distribution model (distribution coefficient) in units of section K of reactive power, expands the total reactive power value in section K to each node N to obtain the active power and reactive power of each node N, and inputs these into a power flow calculation using a second equation to estimate the voltage distribution of each node N (state estimation 2).

[0054] As described above, the state estimation device 200 according to this embodiment uses the voltage, current, and phase of the switch SW with a sensor installed on the power distribution system 1000 and the power consumption measured from the smart meter SM of the customer as measurement values, and uses the system configuration data (system information table 600) composed of the load capacity of the power distribution system 1000, the power source capacity including solar power generation, line data, transformer data, etc., to estimate the voltage and current (power flow) at unmeasured points in the power distribution system 1000 at regular intervals.

[0055] Note that the state estimation unit 203 may calculate the first equation after multiplying the power flow measurement value and the active power measurement value by a weight coefficient determined such that the longer the measurement period, the smaller the weight.

[0056] That is, in this embodiment, since the power flow measurement value can be obtained at a 1-minute cycle and the active power measurement value can be obtained at a 30-minute cycle, the state estimation unit 203 may calculate the first equation after multiplying the active power measurement value by a smaller weight coefficient than the power flow measurement value.

[0057] In such a manner, the influence degree on the state estimation result for the measurement value with a slow measurement cycle is reduced, and it becomes possible to perform state estimation with higher accuracy.

[0058] Also, the state estimation unit 203 may repeatedly calculate the total reactive power value in the section K of the power distribution system 1000 and the active power at a plurality of nodes N in the section K by calculating the first equation using the latest power flow measurement value and active power measurement value every predetermined period (for example, every 1 minute).

[0059] In such a manner, it becomes possible to always estimate the latest state of the power distribution system 1000. <<<Details of the process>>>

[0060] A first specific example of the state estimation process executed by the state estimation device 200 will be described using the process flow of FIG. 7.

[0061] Note that the state estimation device 200 performs calculations by modeling the entire section K of the power distribution system 1000 at once. For the sake of simplicity of explanation, the state estimation process in the section K of the power distribution system 1000 shown in FIG. 5 will be described.

[0062] The power distribution system 1000 shown in FIG. 5 is configured to include two switchgears SW with sensors, two nodes N, and one section K. Each node N and the switchgear SW with sensors are connected by a power distribution line 1200.

[0063] Also, the measured values (active power measurement values) of the smart meters SM for each node N are aggregated, stored in the database of the storage device 240, and used for state estimation.

[0064] The following physical quantities use normalized pu units. The time t uses a discretized value.

[0065] TIFF0007687096000001.tif14170

[0066]

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[0067] TIFF0007687096000003.tif21170

[0068] TIFF0007687096000004.tif13170

[0069]

Number

[0070] TIFF0007687096000006.tif6170

[0071] At this time, the overall measured value y at time t t is given by the following equation (3).

[0072]

Number

[0073] However, the measurement period is set to 1 minute for the switch SW with sensor and 30 minutes for the smart meter SM, and the operation period for state estimation is set to 1 minute.

[0074] Therefore, the measured values from the switch SW with sensor are updated every operation period, but the measured values from the smart meter SM are not updated during 30 operations and a fixed value is used.

[0075] TIFF0007687096000008.tif6170

[0076]

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[0077] TIFF0007687096000010.tif12170

[0078] TIFF0007687096000011.tif13170

[0079]

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[0080] TIFF0007687096000013.tif19170

[0081] For example, create L as shown in (6) below.

[0082]

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[0083] TIFF0007687096000015.tif6170

[0084]

Number

[0085] Therefore, the reactive power of node N1 and node N2 is expressed as in (8).

[0086] [Number]

[0087] TIFF0007687096000018.tif13170

[0088] TIFF0007687096000019.tif6170

[0089] [Number]

[0090] The state estimation device 200 determines the distribution coefficient by data analysis such as parameter adjustment using data related to facilities such as the capacity of load facilities, the capacity of solar power generation facilities, and the power contract form in the power distribution system 1000, and measurement data of past reactive power (S1020).

[0091] TIFF0007687096000021.tif13170

[0092] [Number] [Number]

[0093] However, H is the linearization matrix of h. At this time, when F = HL, the state equation F (the first equation) becomes the following (12). In this way, the state equation F incorporates the distribution coefficient, and thereby, the total reactive power in the section K can be converted into the reactive power at a plurality of nodes N.

[0094]

Number

[0095] TIFF0007687096000025.tif13170

[0096] TIFF0007687096000026.tif19170

[0097] Therefore, when the measurement period of the switch SW with a sensor is used as the calculation period of the state estimation, there is a period during which the measurement value from the smart meter SM is not updated. In that case, the fluctuations that can actually occur cannot be captured.

[0098] TIFF0007687096000027.tif12170

[0099] TIFF0007687096000028.tif12170

[0100]

Number

Number

[0101] TIFF0007687096000031.tif26170

[0102] Regarding the weights, by comparing with the weights of the measurement values from the switch SW with a sensor and reducing the weights of the measurement values from the smart meter SM, the influence of the measurement values from the smart meter on the estimation result of the state value by the state estimation can be reduced.

[0103] TIFF0007687096000032.tif19170

[0104] Thus, even when the measurement values from the smart meter SM are not updated, the fluctuations can be reflected in detail in the state values using the measurement values from the switch SW with a sensor.

[0105] The state estimation device 200 determines the specific values of the weights by performing analysis such as simulation of state estimation using past measurement value data.

[0106] TIFF0007687096000033.tif12170

[0107] For example, when the state estimation device 200 applies the least squares method as the state estimation method, the state values are obtained by the following equation (15).

[0108]

Equation

[0109] As the state estimation method, various state methods such as the sequential least squares method and the Kalman filter can be applied.

[0110] TIFF0007687096000035.tif6170

[0111]

Equation

[0112] In this embodiment, an example of performing state estimation for a single section K is shown. However, even when performing state estimation for a plurality of sections K, the state values can be estimated by the same calculation.

[0113] Next, a second specific example of the state estimation process performed by the state estimation device 200 will be described.

[0114] In this embodiment, a measurement value vector composed of a measurement value (power flow measurement value) from the switch SW with sensor and a measurement value (active power measurement value) from the smart meter SM is defined, and a state value vector composed of the active power of a plurality of nodes N set in advance and the total reactive power value of a plurality of nodes N within a preset section K is defined, and a state equation (first equation) for calculating the value of the measurement point using the state value vector is defined.

[0115] TIFF0007687096000037.tif13170

[0116]

Number

Number

Number

[0117] TIFF0007687096000041.tif40170

[0118] However, the measurement value from the switch SW with sensor assumes the actual measurement values (for example, voltage, current, phase), and converts them into voltage, active power flow, and reactive power flow. Also, the measurement value from the smart meter SM assumes the amount of power consumed and converts it into the average active power value. Further, the measurement values from the smart meter SM are aggregated in units of preset nodes and given to the measurement value vector.

[0119] TIFF0007687096000042.tif12170

[0120]

Number

Number

[0121] TIFF0007687096000045.tif13170

[0122] The weight matrix W is a matrix with the weight vector w as diagonal elements, as shown in (22) below.

[0123]

Equation

[0124] TIFF0007687096000047.tif27170

[0125] If all weights are set to 1, the state value when all measurement values are equally considered is calculated. However, the measurement periods of the switch SW with sensor and the smart meter SM are different, and generally, the measurement values from the smart meter SM have a longer measurement period. When calculating the state estimation according to the measurement values with a shorter measurement period, the measurement values with a longer measurement period will use the value before update as the measurement value until the value is updated.

[0126] In addition, the measurement values from the smart meter SM are values obtained by converting the power consumption into the average value of the active power, and further include an element of time delay. Therefore, when performing state estimation according to the measurement period of the switch SW with sensor, the measurement values from the smart meter SM are considered to have low reliability as data.

[0127] Considering these factors, by comparing the value of the weight vector related to the smart meter SM with the value related to the switch SW with sensor and giving a smaller value, the influence degree of the measurement values of the smart meter SM on the state estimation can be weakened, and it becomes possible to mainly reflect the variable elements related to the node active power in the state value.

[0128] The state estimation device 200 performs state estimation by presetting a weight vector through analysis using past data.

[0129] TIFF0007687096000048.tif12170

[0130] TIFF0007687096000049.tif26170

[0131]

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[0132] TIFF0007687096000051.tif6170

[0133]

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[0134] TIFF0007687096000053.tif6170

[0135] TIFF0007687096000054.tif20170

[0136] TIFF0007687096000055.tif13170

[0137] TIFF0007687096000056.tif13170

[0138]

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[0139] TIFF0007687096000058.tif20170

[0140] Note that the matrix L requires a model representing the distribution of reactive power, which can be created, for example, through analysis using past data or using values related to load equipment and solar power generation equipment.

[0141] When using the matrix L, the linearized power flow equation is expressed as follows in (26).

[0142] [Number]

[0143] TIFF0007687096000060.tif13170

[0144] As described above, the state estimation device 200, the control method of the state estimation device 200, and the program 700 according to the present embodiment have been described in detail. According to the present embodiment, even when the number of measuring instruments is smaller than the number of locations (estimation points) where estimation is to be performed in the distribution system 1000, it is possible to estimate the state of the distribution system 1000.

[0145] Note that the above-described embodiments are for facilitating the understanding of the present invention and are not for limiting the interpretation of the present invention. The present invention can be changed and improved without departing from its gist, and equivalents thereof are also included in the present invention.

[0146] For example, in addition to state estimation methods independent at each time section such as the least squares method, the weighted least squares method, and the load correction type state estimation method, the present invention can also be applied to state estimation methods that perform sequential processing in a time series such as the Kalman filter.

Explanation of Reference Numerals

[0147] 200 State estimation device 201 Measured value acquisition unit 202 Distribution coefficient acquisition unit 203 State estimation unit 204 Reactive power calculation unit 210 CPU 220 Memory 230 Communication device 240 Storage device 250 Input device 260 Output device 270 Recording medium reading device 500 Network 600 System information table 700 State estimation device control program 800 Recording medium 1000 Power distribution system 1100 Power distribution and transformation substation 1200 Power distribution line Switch with SW sensor SM Smart meter N Node K Section

Claims

1. A state estimation device for obtaining the state of a section configured to have a plurality of nodes in a power distribution system, a measurement value acquisition unit that acquires power flow measurement values at the ends of the section and active power measurement values at the plurality of nodes; a distribution coefficient acquisition unit that acquires distribution coefficients representing the ratios of reactive power at the plurality of nodes; a state estimation unit that inputs the power flow measurement values and the active power measurement values into a first equation configured to be able to estimate the state of the section by converting the total reactive power in the section into reactive power at the plurality of nodes using the distribution coefficients, thereby obtaining the total reactive power in the section and the active power at the plurality of nodes as the state of the section; A state estimation device comprising the above.

2. The state estimation device according to claim 1, further comprising a reactive power calculation unit that calculates the reactive power at the plurality of nodes using the total reactive power in the section and the distribution coefficients; The state estimation unit further calculates the voltage values at the plurality of nodes as the state of the section by calculating a predetermined second equation using the reactive power at the plurality of nodes and the active power at the plurality of nodes. A state estimation device.

3. The state estimation device according to claim 1 or 2, wherein the state estimation unit calculates the first equation after multiplying the power flow measurement values and the active power measurement values by a weighting coefficient determined such that the longer the measurement period, the smaller the weight. A state estimation device.

4. The state estimation device according to any one of claims 1 to 3, wherein the distribution coefficient acquisition unit acquires the distribution coefficients by performing predetermined data analysis using at least any one of data related to facilities connected to the plurality of nodes and past measurement data of reactive power at the plurality of nodes. A state estimation device.

5. The state estimation device according to any one of claims 1 to 4, wherein the state estimation unit repeatedly calculates the total reactive power in the section and the active power at the plurality of nodes by calculating the first equation using the latest power flow measurement values and the active power measurement values every predetermined period. A state estimation device.

6. A control method for a state estimation device that performs state estimation of a section configured to have a plurality of nodes in a power distribution system, wherein the state estimation device, ​ Obtain the tidal current measurement values at the ends of the interval and the active power measurement values at the plurality of nodes. Obtain a distribution coefficient representing the ratio of reactive power at the plurality of nodes. Input the tidal current measurement values and the active power measurement values into a first equation configured to be able to estimate the state of the interval by converting the total reactive power in the interval into reactive power at the plurality of nodes using the distribution coefficient, thereby obtaining the total reactive power in the interval and the active power at the plurality of nodes as the state of the interval. A control method for a state estimation device.

7. In a computer that performs state estimation of an interval configured to have a plurality of nodes in a distribution system, A procedure for obtaining the tidal current measurement values at the ends of the interval and the active power measurement values at the plurality of nodes, A procedure for obtaining a distribution coefficient representing the ratio of reactive power at the plurality of nodes, A procedure for inputting the tidal current measurement values and the active power measurement values into a first equation configured to be able to estimate the state of the interval by converting the total reactive power in the interval into reactive power at the plurality of nodes using the distribution coefficient, thereby obtaining the total reactive power in the interval and the active power at the plurality of nodes as the state of the interval. A program for causing the above to be executed.

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