Power distribution network state estimation system, power distribution network state estimation device, power distribution network state estimation method, and program

Abstract

This power distribution network state estimation system comprises: a measurement value acquisition unit that acquires a measurement value of a voltage and a tidal current in a first switch installed on a first power distribution line, a measurement value of a first connection end voltage at a first connection end of a second switch of which one end is connected to the power distribution line, and a measurement value of a second connection end voltage at a second connection end of the second switch; a voltage drop calculation unit that calculates a value indicating the voltage drop from the first switch to the second switch by using the measurement value of the tidal current; a correlation calculation unit that calculates a temporal correlation between the value indicating the voltage drop and the value obtained by subtracting the measurement value of the first connection end voltage from the measurement value of the voltage in the first switch, and calculates a temporal correlation between the value indicating the voltage drop and the value obtained by subtracting the measurement value of the second connection end voltage from the measurement value of the voltage in the first switch; and a determination unit for estimating, on the basis of at least said temporal correlations, the connection end, from among the first connection end and the second connection end, that is connected to the first power distribution line.

Description

Power distribution network state estimation system, power distribution network state estimation device, power distribution network state estimation method, and program

[0001] The present disclosure relates to a power distribution network state estimation system, a power distribution network state estimation device, a power distribution network state estimation method, and a program.

[0002] Among the switches installed in the power distribution network, there are sensor-equipped switches equipped with sensors that measure voltage and power flow (active power and reactive power). The voltage and power flow measured by these sensors are used for voltage control to maintain appropriate voltages at various points in the power distribution network.

[0003] Furthermore, Patent Document 1 discloses a connection phase estimation method for estimating the connection phase between a first distribution line and a second distribution line based on a correlation value of line currents in a distribution network in which a set of first distribution lines branches into a plurality of sets of second distribution lines.

[0004] Japanese Patent Application Publication No. 2018-151089

[0005] However, in a system that collects voltages at both ends of a sensor-equipped switch, the connection direction of the switch may be set incorrectly. The connection phase estimation method described in Patent Document 1 has the problem that it can estimate the connection phase but cannot estimate the connection direction of the switch.

[0006] The present disclosure has been made in consideration of the above circumstances, and provides a power distribution network state estimation system, a power distribution network state estimation device, a power distribution network state estimation method, and a program that can estimate the connection direction of a sensor-equipped switch.

[0007] This disclosure has been made to solve the above-mentioned problems, and one aspect of the disclosure is a measurement value acquisition unit that acquires measurement values ​​of a voltage and a power flow at a first switch installed on a first distribution line, a measurement value of a first connection end voltage at a first connection end of a second switch having one end connected to the first distribution line, and a measurement value of a second connection end voltage at a second connection end of the second switch; and a voltage drop calculation unit that calculates a value indicating a first voltage drop from the first switch to the second switch using the measurement value of the power flow. a correlation calculation unit that calculates a first time correlation between a value obtained by subtracting a measured value of the first connection end voltage from a measured value of the voltage and a value indicating the first voltage drop, and calculates a second time correlation between a value obtained by subtracting a measured value of the second connection end voltage from the measured value of the voltage and the value indicating the first voltage drop; and a determination unit that estimates which of the first connection end and the second connection end is connected to the first distribution line based on at least the first time correlation and the second time correlation.

[0008] Another aspect of the present disclosure is the above-mentioned power distribution network state estimation system, wherein the measured value of the power flow includes active power and reactive power at the first switch, and the voltage drop calculation unit calculates, as the value indicating the first voltage drop, the sum of a value obtained by multiplying a preset value indicating the resistance of the first distribution line by the active power and a value obtained by multiplying a preset value indicating the reactance of the first distribution line by the reactive power.

[0009] Another aspect of the present disclosure is the above-described power distribution network state estimation system, including a display unit that, when the determination unit determines that the estimation result of the connection end connected to the first power distribution line does not match the pre-stored connection relationship between the second switch and the first power distribution line, displays a message notifying the user that the estimation result does not match.

[0010] Another aspect of the present disclosure is the above-mentioned power distribution network state estimation system, in which the measurement value acquisition unit acquires measurement values ​​of a voltage and a power flow at a third switch installed on a second distribution line to which the other end of the second switch is connected, the voltage drop calculation unit calculates a value indicating a second voltage drop from the third switch to the second switch using the measurement value of the power flow at the third switch, the correlation calculation unit calculates a third time correlation between a value obtained by subtracting the measurement value of the first connection end voltage from the measurement value of the voltage at the third switch and the value indicating the second voltage drop, and calculates a fourth time correlation between a value obtained by subtracting the measurement value of the second connection end voltage from the measurement value of the voltage at the third switch and the value indicating the second voltage drop, and the determination unit estimates which of the first connection end and the second connection end is connected to the first distribution line based on at least the first time correlation, the second time correlation, the third time correlation, and the fourth time correlation.

[0011] Another aspect of the present disclosure is a power distribution system including a measurement value acquiring unit that acquires measurement values ​​of a voltage and a power flow at a first switch installed on a first distribution line, a measurement value of a first connection end voltage at a first connection end of a second switch having one end connected to the first distribution line, and a measurement value of a second connection end voltage at a second connection end of the second switch; a voltage drop calculating unit that calculates a value indicating a first voltage drop from the first switch to the second switch using the measurement value of the power flow; a correlation calculation unit that calculates a first time correlation between a value obtained by subtracting a measured value of the first connection end voltage from the measured value of the voltage and a value indicating the first voltage drop, and calculates a second time correlation between a value obtained by subtracting a measured value of the second connection end voltage from the measured value of the voltage and the value indicating the first voltage drop; and a determination unit that estimates which of the first connection end and the second connection end is connected to the first distribution line based on at least the first time correlation and the second time correlation.

[0012] Another aspect of the present disclosure is a method for estimating a state of a power distribution network, comprising the steps of: acquiring measured values ​​of a voltage and a power flow at a first switch installed on a first distribution line; acquiring a measured value of a first connection end voltage at a first connection end of a second switch having one end connected to the first distribution line; and acquiring a measured value of a second connection end voltage at a second connection end of the second switch; calculating a value indicating a first voltage drop from the first switch to the second switch using the measured values ​​of the power flow; calculating a first time correlation between a value obtained by subtracting the measured value of the first connection end voltage from the measured value of the voltage and the value indicating the first voltage drop; and calculating a second time correlation between a value obtained by subtracting the measured value of the second connection end voltage from the measured value of the voltage and the value indicating the first voltage drop; and estimating which of the first connection end and the second connection end is connected to the first distribution line based at least on the first time correlation and the second time correlation.

[0013] Another aspect of the present disclosure is a program that causes a computer to function as: a measurement value acquisition unit that acquires measurement values ​​of voltage and power flow at a first switch installed on a first distribution line, a measurement value of a first connection end voltage at a first connection end of a second switch having one end connected to the first distribution line, and a measurement value of a second connection end voltage at a second connection end of the second switch; a voltage drop calculation unit that calculates a value indicating a first voltage drop from the first switch to the second switch using the measurement values ​​of power flow; a correlation calculation unit that calculates a first time correlation between a value obtained by subtracting the measurement value of the first connection end voltage from the measurement value of the voltage and the value indicating the first voltage drop, and calculates a second time correlation between a value obtained by subtracting the measurement value of the second connection end voltage from the measurement value of the voltage and the value indicating the first voltage drop; and a determination unit that estimates which of the first connection end and the second connection end is connected to the first distribution line based at least on the first time correlation and the second time correlation.

[0014] According to this disclosure, a power distribution network state estimation system, a power distribution network state estimation device, a power distribution network state estimation method, and a program can estimate the connection direction of a sensor-equipped switch.

[0015] Fig. 1 is a schematic block diagram showing the connection relationship of the power distribution network state estimation system 10 according to an embodiment of the present disclosure. Fig. 2 is a schematic block diagram showing the configuration of the power distribution network state estimation system 10 in the same embodiment. Fig. 3 is a graph showing a display example (part 1) by the display unit 15 in the same embodiment. Fig. 4 is a graph showing a display example (part 2) by the display unit 15 in the same embodiment. Fig. 5 is a flowchart illustrating an operation example of the power distribution network state estimation system 10 in the same embodiment. Fig. 6 is a flowchart illustrating an operation example of the power distribution network state estimation system 10 in a modified example of the same embodiment. Fig. 7 is an explanatory diagram illustrating the hardware configuration of each device according to the same embodiment and the modified example.

[0016] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic block diagram showing the connection relationship of a power distribution network state estimation system 10 according to an embodiment of the present disclosure. The power distribution network state estimation system 10 is a system that estimates the state of a power distribution network. Note that the power distribution network state estimation system 10 may be configured as a single device (power distribution network state estimation device). The state of the power distribution network estimated by the power distribution network state estimation system 10 includes the connection direction of the switch Sc, but may also include voltages, current flows, and the like at various points in the power distribution network. A centralized voltage control system 20 performs voltage control to maintain appropriate voltages at various points in the power distribution network based on the state of the power distribution network estimated by the power distribution network state estimation system 10. A measurement value collection system 30 collects measurement values ​​from sensors arranged in the power distribution network, including sensors equipped in the switches Sa, Sb, and Sc.

[0017] Each of the power distribution grid state estimation system 10, the centralized voltage control system 20, and the measurement value collection system 30 may be realized by one or more computers reading and executing a program. Each of the power distribution grid state estimation system 10, the centralized voltage control system 20, and the measurement value collection system 30 may be configured as a single device or as a plurality of devices connected via a network or the like.

[0018] The switch Sa (first switch) is a switch with a sensor arranged on a distribution line Fa (first distribution line) that constitutes a power distribution network. The distribution line Fa is connected to a transformer Ta via the switch Sa. The load center La is the load center of the distribution line Fa. The switch Sa is normally closed to supply power from the transformer Ta to the distribution line Fa. The switch Sb (third switch) is a switch with a sensor arranged on a distribution line Fb (second distribution line) that constitutes a power distribution network. The distribution line Fb is connected to a transformer Tb via the switch Sb. The load center Lb is the load center of the distribution line Fb. The switch Sb is normally closed to supply power from the transformer Tb to the distribution line Fb.

[0019] The sensors provided in the switches Sa and Sb measure the voltage and power flow (active power and reactive power) at each switch and supply these measurement values ​​to the measurement value collection system 30. Note that the switches Sa and Sb are normally closed, and the voltages at both ends are equal. Therefore, the voltage measurement values ​​measured by the sensors and supplied to the measurement value collection system 30 may be the voltages at either the transformer Ta, Tb side or the distribution line Fa, Fb side of the switches Sa and Sb, or may be the voltages at both ends.

[0020] The switch Sc (second switch) is a switch with a sensor arranged such that one end (S end) is connected to the distribution line Fa and the other end (T end) is connected to the distribution line Fb. When the switch Sc is closed, a loop is formed between the distribution lines Fa and Fb, and the switch Sc is normally open. The sensor included in the switch Sc measures at least the voltages at the S end and the T end and supplies these measurement values ​​to the measurement value collection system 30. Note that in FIG. 1 , the S end is connected to the distribution line Fa and the T end is connected to the distribution line Fb, but this is the connection direction setting stored in the distribution grid state estimation system 10. That is, the distribution grid state estimation system 10 is configured to recognize the measurement value acquired from the measurement value collection system 30 as the voltage at the S end as the voltage at the end of the switch Sc on the distribution line Fa side, and to recognize the measurement value acquired as the voltage at the T end as the voltage at the end of the switch Sc on the distribution line Fb side. The power distribution network state estimation system 10 in this embodiment determines whether this setting is correct or incorrect. In addition to consumers, distributed power sources such as solar cells and branch lines may be connected to the power distribution lines Fa and Fb.

[0021] 2 is a schematic block diagram showing the configuration of a power distribution network state estimation system 10 according to this embodiment. The power distribution network state estimation system 10 includes a measurement value acquisition unit 11, a voltage drop calculation unit 12, a correlation calculation unit 13, a determination unit 14, and a display unit 15.

[0022] The measurement value acquiring unit 11 acquires measurement values ​​of the voltage Va and power flow (e.g., active power Pa, reactive power Qa) at a switch Sa installed on the distribution line Fa, a measurement value of the voltage Vs (first connection end voltage) at an S end (first connection end) of a switch Sc, one end of which is connected to the distribution line Fa, and a measurement value of the voltage Vt (second connection end voltage) at a T end (second connection end) of the switch Sc. These voltage and power flow measurement values ​​may be average values ​​for a predetermined period (e.g., one day) over a predetermined time period (e.g., one minute) at predetermined intervals (e.g., one minute). Note that these average values ​​may be calculated from instantaneous values ​​by the measurement value collecting system 30 and acquired by the measurement value acquiring unit 11, or may be calculated by the measurement value acquiring unit 11 based on instantaneous values ​​acquired from the measurement value collecting system 30.

[0023] The voltage drop calculation unit 12 calculates a value indicating a first voltage drop from the switch Sa to the switch Sc using the measurement value of the power flow. Note that when the measurement value acquisition unit 11 acquires the measurement values ​​of the active power Pa and the reactive power Qa as the power flow, the voltage drop calculation unit 12 may calculate the sum of a value obtained by multiplying a preset value Ra indicating the resistance of the distribution line Fa by the active power Pa and a value obtained by multiplying a preset value Xa indicating the reactance of the distribution line Fa by the reactive power Qa (i.e., PaRa+QaXa) as the value indicating the voltage drop (first voltage drop).

[0024] Ra may be the resistance of a predetermined length of the distribution line Fa (for example, from the switch Sa to the load center La, or from the switch Sa to the switch Sc). Xa may be the reactance of a predetermined length of the distribution line Fa (for example, from the switch Sa to the load center La, or from the switch Sa to the switch Sc). Note that these predetermined lengths or the position of the load center La may be constant values ​​or may vary depending on the time.

[0025] The correlation calculation unit 13 calculates a time correlation (first time correlation) between a value obtained by subtracting the measured value of the voltage Vs from the measured value of the voltage Va and a value indicating the voltage drop (first voltage drop) calculated by the voltage drop calculation unit 12. The correlation calculation unit 13 also calculates a time correlation (second time correlation) between a value obtained by subtracting the measured value of the voltage Vt from the measured value of the voltage Va and a value indicating the voltage drop (first voltage drop) calculated by the voltage drop calculation unit 12.

[0026] The determination unit 14 estimates which of the S-terminal and the T-terminal is connected to the power distribution line Fa based on at least the first time correlation and the second time correlation calculated by the correlation calculation unit 13. The determination unit 14 estimates that the connection terminal corresponding to the larger of the first time correlation and the second time correlation (the one with higher correlation) is connected to the power distribution line Fa. Note that, when making the estimation, other conditions may be used, such as the value of the larger time correlation exceeding a predetermined threshold. Here, the connection terminal corresponding to the first time correlation is the S-terminal at which the voltage Vs used to calculate the first time correlation was measured, and the connection terminal corresponding to the second time correlation is the T-terminal at which the voltage Vt used to calculate the second time correlation was measured. Since the switch Sc is normally open, the voltage at the connection end of the switch Sc on the distribution line Fa side and the voltage at the connection end of the switch Sc on the distribution line Fb side do not normally match, and the time correlation on the distribution line Fa side is generally greater than the time correlation on the distribution line Fb side. The determination unit 14 makes use of this fact to perform its estimation.

[0027] When the determination unit 14 determines that the estimation result of the connection end connected to the distribution line Fa does not match the connection relationship between the switch Sc and the distribution line Fa that was previously stored in the distribution grid state estimation system 10, the display unit 15 displays a message notifying the operator that the connection relationship between the switch Sc and the distribution line Fa that was previously stored in the distribution grid state estimation system 10. Based on this message, the operator can correct the connection relationship between the switch Sc and the distribution line Fa that was previously stored in the distribution grid state estimation system 10. The message notifying the operator that the connection relationship between the switch Sc and the distribution line Fa that was previously stored in the distribution grid state estimation system 10 may be displayed in text, or may be displayed using a graph showing the relationship between the measured voltage value and the calculated voltage drop, a graph showing the correlation, or the like.

[0028] This display may be performed using a display provided in the power distribution network state estimation system 10, or may be performed using a display provided in another device that is communicatively connected to the power distribution network state estimation system 10.

[0029] FIG. 3 is a graph showing a display example (part 1) of the display unit 15 in this embodiment. FIG. 3 is a graph showing the relationship between the measured values ​​of voltages Va, Vs, and Vt and the voltage drop (PaRa + QaXa) calculated by the voltage drop calculation unit 12. In the graph of FIG. 3, the horizontal axis represents the length of the distribution line Fa, and the vertical axis represents voltage. On the horizontal axis, Sa represents the position of the switch Sa, La represents the position of the load center La, and Sc represents the position of the switch Sc. The solid line in the graph is a straight line connecting the voltage Va at the switch Sa and the voltage Vs at the switch Sc. The dashed line in the graph is a straight line connecting the voltage Va at the switch Sa and the voltage Va - (PaRa + QaXa) at the load center La, and further connecting the voltage Va to the switch Sc. These values ​​are values ​​at a certain time, and the time may be set by the operator, or may be average values ​​over a predetermined period.

[0030] The voltage Va-(PaRa+QaXa) indicates the voltage at the switch Sc based on the calculated voltage drop. If the connection direction of the switch Sc stored in the power distribution grid state estimation system 10 is correct, this value is expected to be close to the voltage Vs. Therefore, by comparing this value with the voltages Vs and Vt, the operator can also confirm (estimate) whether the connection direction (S end, T end) of the switch Sc stored in the power distribution grid state estimation system 10 is incorrect.

[0031] FIG. 4 is a graph showing a second example of a display by the display unit 15 in this embodiment. In FIG. 4, the horizontal axis represents PaRa+QaXa, and the vertical axis represents Va-Vs. FIG. 4 is a graph plotting points consisting of PaRa+QaXa and Va-Vs at each time. If there is a time correlation between PaRa+QaXa and Va-Vs, a regularity will appear in the set of plotted points as shown in FIG. 4. However, if there is no time correlation, no regularity will appear. By referring to the graph in FIG. 4, an operator can also confirm (estimate) whether there is an error in the connection direction (S terminal, T terminal) of the switch Sc stored in the power distribution grid state estimation system 10. Note that the display unit 15 may also display a graph plotting points consisting of PaRa+QaXa and Va-Vt at each time.

[0032] Fig. 5 is a flowchart illustrating an example of operation of the power distribution network state estimation system 10 according to the present embodiment. Fig. 5 is a flowchart illustrating a process of determining the connection setting of the switch Sc by the power distribution network state estimation system 10. This determination process may be started by an operator's instruction, may be started periodically, or may be started when the setting related to the switch Sc is changed.

[0033] First, the measurement value acquisition unit 11 acquires the measurement values ​​(Va, Pa, Qa, Vs, Vt) at the switches Sa and Sc (step Sa1). Next, the voltage drop calculation unit 12 calculates the voltage drop Ca from the switch Sa to the switch Sc based on the power flow (active power Pa, reactive power Qa) at the switch Sa (step Sa2). This voltage drop Ca is, for example, PaRa + QaXa.

[0034] Next, the correlation calculation unit 13 calculates the correlation between the voltage drop Ca calculated in step Sa2 and the measured voltage drop A (step Sa3). The measured voltage drop A is, for example, Va-Vs or Va-Vt. Next, the determination unit 14 determines whether the connection setting of the switch Sc stored in the power distribution network state estimation system 10 is correct or incorrect based on the correlation calculated in step Sa3 (step Sa4). If the determination result in step Sa4 is incorrect (the connection setting is incorrect) (step Sa5—Yes), the display unit 15 notifies the operator that the connection setting is incorrect (step Sa6). On the other hand, if the determination result in step Sa4 is not incorrect (the connection setting is correct) (step Sa5—No), the power distribution network state estimation system 10 ends the process of determining the connection setting of the switch Sc.

[0035] In this way, by using the time correlation between the voltage drop from the switch Sa calculated based on the power flow and the voltage drop from the switch Sa based on the measured voltage value, the power distribution network state estimation system 10 can estimate the connection direction of the sensor-equipped switch Sc.

[0036] <Modification> In the above-described embodiment, the measurement value of the switch Sa and the measurement value of the switch Sc were used to determine the connection setting of the switch Sc. However, in this modification, the measurement value of the switch Sb may also be used. The measurement value acquisition unit 11, voltage drop calculation unit 12, correlation calculation unit 13, determination unit 14, and display unit 15 in this modification described below are the same as those in the above-described embodiment, but also perform processing using the measurement value of the switch Sb. The processing added to the above-described embodiment in this modification will be described below.

[0037] The measurement value acquisition unit 11 acquires measurement values ​​of the voltage Vb and the power flow (active power Pb, reactive power Qb) at a switch Sb (a third switch) installed on a distribution line Fb to which the T-end (the end considered to be the T-end) of the switch Sc is connected. The voltage drop calculation unit 12 calculates a value indicating the voltage drop (second voltage drop) from the switch Sb to the switch Sc using the measurement value of the power flow at the switch Sb.

[0038] The correlation calculation unit 13 calculates a time correlation (third time correlation) between a value obtained by subtracting the measured value of the voltage Vs at the switch Sb from the measured value of the voltage Vb at the switch Sb and a value indicating the second voltage drop calculated by the voltage drop calculation unit 12. The correlation calculation unit 13 also calculates a time correlation (fourth time correlation) between a value obtained by subtracting the measured value of the voltage Vt at the switch Sb from the measured value of the voltage Vb at the switch Sb and a value indicating the second voltage drop calculated by the voltage drop calculation unit 12.

[0039] The determination unit 14 estimates which of the S-terminal and the T-terminal is the connection terminal connected to the distribution line Fa based on at least the first time correlation, the second time correlation, the third time correlation, and the fourth time correlation. For example, the determination unit 14 may estimate that the T-terminal is the connection terminal connected to the distribution line Fa when the first time correlation is smaller than the second time correlation or the third time correlation is larger than the fourth time correlation. Furthermore, the determination unit 14 may estimate that the S-terminal is the connection terminal connected to the distribution line Fa when the first time correlation is larger than the second time correlation or the third time correlation is smaller than the fourth time correlation.

[0040] Furthermore, when the first time correlation is smaller than the second time correlation and the third time correlation is larger than the fourth time correlation, the determination unit 14 may estimate that the T-end is the connection end connected to the distribution line Fa. Similarly, when the first time correlation is larger than the second time correlation and the third time correlation is smaller than the fourth time correlation, the determination unit 14 may estimate that the S-end is the connection end connected to the distribution line Fa.

[0041] Fig. 6 is a flowchart illustrating an example of the operation of the power distribution network state estimation system 10 in this modified example. Fig. 6 is also a flowchart of the process of determining the connection setting of the switch Sc by the power distribution network state estimation system 10. The start timing of this determination process is the same as in the above-described embodiment.

[0042] First, the measurement value acquisition unit 11 acquires the measurement values ​​(Va, Pa, Qa, Vb, Pb, Qb, Vs, Vt) at the switches Sa, Sb, and Sc (step Sb1). Next, the voltage drop calculation unit 12 calculates the voltage drop Ca from the switch Sa to the switch Sc based on the power flow (Pa, Qa) at the switch Sa (step Sa2). This voltage drop Ca is, for example, PaRa+QaXa. Next, the voltage drop calculation unit 12 calculates the voltage drop Cb from the switch Sb to the switch Sc based on the power flow (Pb, Qb) at the switch Sb (step Sb2). This voltage drop Cb is, for example, PbRb+QbXb.

[0043] Next, the correlation calculation unit 13 calculates the correlation between the voltage drop Ca calculated in step Sa2 and the measured voltage drop A (step Sa3). Next, the correlation calculation unit 13 calculates the correlation between the voltage drop Cb calculated in step Sb2 and the measured voltage drop B (step Sb3). The measured voltage drop B is, for example, Vb-Vs or Vb-Vt. Next, the determination unit 14 determines whether the connection setting of the switch Sc stored in the power distribution network state estimation system 10 is correct based on the correlation calculated in steps Sa3 and Sb3 (step Sb4). If the determination result in step Sb4 is incorrect (the connection setting is incorrect) (step Sa5—Yes), the display unit 15 notifies the operator that the connection setting is incorrect (step Sa6). On the other hand, if the determination result in step Sa4 is not incorrect (the connection setting is correct) (step Sa5—No), the power distribution network state estimation system 10 ends the process of determining the connection setting of the switch Sc.

[0044] In this way, in the modified example, by also using the voltage drop from the switch Sb to the switch Sc, the connection setting of the switch Sc can be determined with even higher accuracy.

[0045] FIG. 7 is an explanatory diagram illustrating the hardware configuration of each device according to the above-described embodiment and modified examples. The devices are the power distribution grid state estimation system 10, the centralized voltage control system 20, and the measurement value collection system 30. Each device includes an input / output module I, a storage module M, and a control module P. The input / output module I includes some or all of the following: the communication module H11, the connection module H12, the pointing device H21, the keyboard H22, the display H23, the button H3, the microphone H41, the speaker H42, the camera H51, and the sensor H52. The storage module M includes a drive H7. The storage module M may further include some or all of the memory H8. The control module P includes a memory H8 and a processor H9. These hardware components are connected to each other via a bus (Bus) and receive power from a power supply H6.

[0046] The connection module H12 is a digital input / output port such as a USB (Universal Serial Bus). In the case of a portable device, the pointing device H21, keyboard H22, and display H23 are touch panels. The sensor H52 is an acceleration sensor, a gyro sensor, a GPS receiving module, a proximity sensor, or the like. The power supply H6 is a power supply unit that supplies the electricity necessary to operate each device. In the case of a portable device, the power supply H6 is a battery. The drive H7 is an auxiliary storage medium such as a hard disk drive or a solid-state drive. The drive H7 may be a non-volatile memory such as an EEPROM or a flash memory, or a magneto-optical disk drive or a flexible disk drive. Furthermore, the drive H7 is not limited to being built into each device, but may also be an external storage device connected to the connector of the connection module H12. The memory H8 is a main storage medium such as a random access memory. The memory H8 may also be a cache memory. The memory H8 stores instructions when the instructions are executed by one or more processors H9. The processor H9 is a CPU (Central Processing Unit). The processor H9 may be an MPU (Microprocessing Unit) or a GPU (Graphics Processing Unit). The processor H9 reads programs and various data from the drive H7 via the memory H8 and performs calculations to execute instructions stored in one or more memories H8.

[0047] The input / output module I is used in the power distribution grid state estimation system 10, the centralized voltage control system 20, the measurement value collection system 30, etc. The control module P is used to implement each part of the power distribution grid state estimation system 10, the centralized voltage control system 20, and the measurement value collection system 30. Note that in this specification and the like, the descriptions of the power distribution grid state estimation system 10, the centralized voltage control system 20, and the measurement value collection system 30 may be replaced with the description of the control module P.

[0048] The present disclosure may also be embodied as follows: (1) One embodiment of the present disclosure includes a measurement value acquisition unit that acquires measurement values ​​of a voltage and a power flow at a first switch installed on a first distribution line, a measurement value of a first connection end voltage at a first connection end of a second switch having one end connected to the first distribution line, and a measurement value of a second connection end voltage at a second connection end of the second switch, the second connection end being connected to the first distribution line; a voltage drop calculation unit that calculates a value indicating a first voltage drop from the first switch to the second switch using the measurement value of the power flow; a correlation calculation unit that calculates a first time correlation between a value obtained by subtracting a measurement value of the first connection end voltage from the first voltage drop and a value indicating the first voltage drop, and calculates a second time correlation between a value obtained by subtracting a measurement value of the second connection end voltage from the measurement value of the voltage and the value indicating the first voltage drop; and a determination unit that estimates which of the first connection end and the second connection end is connected to the first distribution line based on at least the first time correlation and the second time correlation.

[0049] This allows the power distribution network state estimation system to estimate the connection direction of the second switch.

[0050] (2) Another embodiment of the present disclosure is the power distribution network state estimation system described in (1), wherein the measured value of the power flow includes active power and reactive power at the first switch, and the voltage drop calculation unit calculates, as the value indicating the first voltage drop, the sum of a value obtained by multiplying a preset value indicating the resistance of the first distribution line by the active power and a value obtained by multiplying a preset value indicating the reactance of the first distribution line by the reactive power.

[0051] This allows the power distribution network state estimation system to estimate the connection direction of the second switch using the voltage drop calculated from the active power and reactive power at the first switch.

[0052] (3) Another embodiment of the present disclosure is the power distribution network state estimation system described in (1) or (2), further including a display unit that, when the determination unit determines that the estimation result of the connection end connected to the first power distribution line does not match the pre-stored connection relationship between the second switch and the first power distribution line, displays a message notifying the user that the estimation result does not match.

[0053] This allows the power distribution network state estimation system to notify the fact that the pre-stored connection direction of the second switch does not match the estimation result if the pre-stored connection direction of the second switch does not match the estimation result.

[0054] (4) Another embodiment of the present disclosure is the power distribution network state estimation system according to any one of (1) to (3), wherein the measurement value acquisition unit acquires measurement values ​​of a voltage and a power flow at a third switch installed on a second power distribution line to which the other end of the second switch is connected, the voltage drop calculation unit calculates a value indicating a second voltage drop from the third switch to the second switch using the measurement value of the power flow at the third switch, and the correlation calculation unit calculates a value indicating a second voltage drop from the measurement value of the voltage at the third switch to the previous voltage. a third time correlation between a value obtained by subtracting the measured value of the first connection end voltage from a value indicating the second voltage drop; a fourth time correlation between a value obtained by subtracting the measured value of the second connection end voltage from the measured value of the voltage at the third switch and a value indicating the second voltage drop; and the determination unit estimates, based at least on the first time correlation, the second time correlation, the third time correlation, and the fourth time correlation, which of the first connection end and the second connection end is connected to the first distribution line.

[0055] This allows the power distribution network state estimation system to estimate the connection direction of the second switch with higher accuracy than (1).

[0056] (5) Another embodiment of the present disclosure provides a power distribution system including: a measurement value acquiring unit that acquires measurement values ​​of a voltage and a power flow at a first switch installed on a first distribution line; a measurement value of a first connection end voltage at a first connection end of a second switch having one end connected to the first distribution line; and a measurement value of a second connection end voltage at a second connection end of the second switch; a voltage drop calculating unit that calculates a value indicating a first voltage drop from the first switch to the second switch using the measurement value of the power flow; The power distribution network state estimation device includes: a correlation calculation unit that calculates a first time correlation between a value obtained by subtracting a measurement value of the first connection end voltage from a measurement value and a value indicating the first voltage drop; and a second time correlation between a value obtained by subtracting a measurement value of the second connection end voltage from the measurement value of the voltage and the value indicating the first voltage drop; and a determination unit that estimates which of the first connection end and the second connection end is connected to the first power distribution line based on at least the first time correlation and the second time correlation.

[0057] This allows the power distribution network state estimation device to estimate the connection direction of the second switch.

[0058] (6) Another embodiment of the present disclosure is a method for estimating a state of a power distribution network, the method including the steps of: acquiring measurement values ​​of a voltage and a power flow at a first switch installed on a first distribution line; acquiring a measurement value of a first connection end voltage at a first connection end of a second switch, one end of which is connected to the first distribution line; and acquiring a measurement value of a second connection end voltage at a second connection end of the second switch; calculating a value indicating a first voltage drop from the first switch to the second switch using the measurement values ​​of the power flow; calculating a first time correlation between a value obtained by subtracting the measurement value of the first connection end voltage from the measurement value of the voltage and the value indicating the first voltage drop; and calculating a second time correlation between a value obtained by subtracting the measurement value of the second connection end voltage from the measurement value of the voltage and the value indicating the first voltage drop; and estimating, based at least on the first time correlation and the second time correlation, which of the first connection end and the second connection end is connected to the first distribution line.

[0059] This allows the power distribution network state estimation method to estimate the connection direction of the second switch.

[0060] (7) Another embodiment of the present disclosure provides a computer including a measurement value acquisition unit that acquires measurement values ​​of a voltage and a power flow at a first switch installed on a first distribution line, a measurement value of a first connection end voltage at a first connection end of a second switch having one end connected to the first distribution line, and a measurement value of a second connection end voltage at a second connection end of the second switch; a voltage drop calculation unit that calculates a value indicating a first voltage drop from the first switch to the second switch using the measurement value of the power flow; a correlation calculation unit that calculates a first time correlation between a value obtained by subtracting the measured value of the first connection end voltage from the measured value of the first voltage drop and a value indicating the first voltage drop, and a second time correlation between a value obtained by subtracting the measured value of the second connection end voltage from the measured value of the first voltage drop and a value indicating the first voltage drop; and a determination unit that estimates which of the first connection end and the second connection end is connected to the first distribution line based at least on the first time correlation and the second time correlation.

[0061] This allows the computer that reads and executes the program to estimate the connection direction of the second switch.

[0062] 1 and 2 may be recorded on a computer-readable recording medium, and the program for realizing the functions of the power distribution grid state estimation system 10, the centralized voltage control system 20, and the measurement value collection system 30 may be read into a computer system and executed to realize the power distribution grid state estimation system 10, the centralized voltage control system 20, and the measurement value collection system 30. Note that the term "computer system" herein includes hardware such as an OS and peripheral devices.

[0063] "Computer-readable recording media" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording media" also includes devices that dynamically store programs for a short period of time, such as communication lines used when transmitting programs over networks like the Internet or communication lines like telephone lines, and devices that store programs for a fixed period of time, such as volatile memory within the computer systems that serve as servers or clients. The programs may also be programs that implement some of the aforementioned functions, or may be programs that can realize the aforementioned functions in combination with programs already stored in the computer system.

[0064] The embodiments of this disclosure have been described in detail above with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of this disclosure.

[0065] REFERENCE SIGNS LIST 10 Power distribution network state estimation system 11 Measurement value acquisition unit 12 Voltage drop calculation unit 13 Correlation calculation unit 14 Determination unit 15 Display unit 20 Centralized voltage control system 30 Measurement value collection system

Claims

1. A power distribution network state estimation system comprising: a measurement value acquisition unit that acquires measurement values ​​of voltage and power flow at a first switch installed on a first distribution line, a measurement value of a first connection end voltage at a first connection end of a second switch having one end connected to the first distribution line, and a measurement value of a second connection end voltage at a second connection end of the second switch; a voltage drop calculation unit that calculates a value indicating a first voltage drop from the first switch to the second switch using the measurement values ​​of power flow; a correlation calculation unit that calculates a first time correlation between a value obtained by subtracting the measurement value of the first connection end voltage from the measurement value of voltage and the value indicating the first voltage drop, and calculates a second time correlation between a value obtained by subtracting the measurement value of the second connection end voltage from the measurement value of voltage and the value indicating the first voltage drop; and a determination unit that estimates which of the first connection end and the second connection end is connected to the first distribution line based at least on the first time correlation and the second time correlation.

2. The power distribution network state estimation system according to claim 1, wherein the measured value of the power flow includes active power and reactive power at the first switch, and the voltage drop calculation unit calculates, as the value indicating the first voltage drop, the sum of a value obtained by multiplying a preset value indicating the resistance of the first distribution line by the active power and a value obtained by multiplying a preset value indicating the reactance of the first distribution line by the reactive power.

3. The power distribution network state estimation system according to claim 1, further comprising a display unit that, when the determination unit determines that the estimation result of the connection end connected to the first power distribution line does not match the pre-stored connection relationship between the second switch and the first power distribution line, displays a message notifying the user that the estimation result does not match.

4. The measurement value acquisition unit acquires measurement values ​​of the voltage and power flow at a third switch installed on a second distribution line to which the other end of the second switch is connected; the voltage drop calculation unit calculates a value indicating a second voltage drop from the third switch to the second switch using the measurement value of the power flow at the third switch; the correlation calculation unit calculates a third time correlation between a value obtained by subtracting the measurement value of the first connection end voltage from the measurement value of the voltage at the third switch and the value indicating the second voltage drop, and calculates a fourth time correlation between a value obtained by subtracting the measurement value of the second connection end voltage from the measurement value of the voltage at the third switch and the value indicating the second voltage drop; and the determination unit estimates the connection end connected to the first distribution line from the first connection end and the second connection end based at least on the first time correlation, the second time correlation, the third time correlation, and the fourth time correlation. The power distribution network state estimation system according to any one of claims 1 to 3.

5. A power distribution network state estimation device comprising: a measurement value acquisition unit that acquires measurement values ​​of voltage and power flow at a first switch installed on a first distribution line, a measurement value of a first connection end voltage at a first connection end of a second switch having one end connected to the first distribution line, and a measurement value of a second connection end voltage at a second connection end of the second switch; a voltage drop calculation unit that calculates a value indicating a first voltage drop from the first switch to the second switch using the measurement values ​​of power flow; a correlation calculation unit that calculates a first time correlation between a value obtained by subtracting the measurement value of the first connection end voltage from the measurement value of voltage and the value indicating the first voltage drop, and calculates a second time correlation between a value obtained by subtracting the measurement value of the second connection end voltage from the measurement value of voltage and the value indicating the first voltage drop; and a determination unit that estimates which of the first connection end and the second connection end is connected to the first distribution line based at least on the first time correlation and the second time correlation.

6. A method for estimating a state of a power distribution network, comprising the steps of: acquiring measured values ​​of voltage and power flow at a first switch installed on a first distribution line, a measured value of a first connection end voltage at a first connection end of a second switch having one end connected to the first distribution line, and a measured value of a second connection end voltage at a second connection end of the second switch; calculating a value indicating a first voltage drop from the first switch to the second switch using the measured values ​​of power flow; calculating a first time correlation between a value obtained by subtracting the measured value of the first connection end voltage from the measured value of voltage and the value indicating the first voltage drop, and calculating a second time correlation between a value obtained by subtracting the measured value of the second connection end voltage from the measured value of voltage and the value indicating the first voltage drop; and estimating which of the first connection end and the second connection end is connected to the first distribution line based at least on the first time correlation and the second time correlation.

7. A program for causing a computer to function as: a measurement value acquisition unit that acquires measurement values ​​of voltage and power flow at a first switch installed on a first distribution line, a measurement value of a first connection end voltage at a first connection end of a second switch having one end connected to the first distribution line, and a measurement value of a second connection end voltage at a second connection end of the second switch; a voltage drop calculation unit that calculates a value indicating a first voltage drop from the first switch to the second switch using the measurement values ​​of power flow; a correlation calculation unit that calculates a first time correlation between a value obtained by subtracting the measurement value of the first connection end voltage from the measurement value of the voltage and the value indicating the first voltage drop, and calculates a second time correlation between a value obtained by subtracting the measurement value of the second connection end voltage from the measurement value of the voltage and the value indicating the first voltage drop; and a determination unit that estimates which of the first connection end and the second connection end is connected to the first distribution line based at least on the first time correlation and the second time correlation.

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