Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J13/00—Circuit arrangements for providing remote monitoring or remote control of equipment in a power distribution network
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J3/00—Circuit arrangements for AC mains or AC distribution networks

Definitions

• This 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.
• switch-equipped switches that are 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 voltage at various points in the power distribution network.
• Patent Document 1 also discloses a connection phase estimation method for estimating the connection phase between a first distribution line and a second distribution line based on the correlation value of the line current in a distribution network in which a set of first distribution lines branches into multiple sets of second distribution lines.
• connection phase estimation method described in Patent Document 1 has the problem that, although it can estimate the connection phase, it cannot estimate the connection direction of the switch.
• This disclosure has been made in light of these 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.
• a voltage drop calculation circuit that includes 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, and a voltage drop calculation circuit 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 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 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 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.
• the measured value of the power flow includes active power and reactive power at the first switch
• the voltage drop calculation unit calculates, as a 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.
• another aspect of the present disclosure is the above-mentioned power distribution network state estimation system, which includes 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 two do not match.
• 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 the first connection end voltage from the measurement value of the voltage at the third switch.
• the determination unit estimates which of the first and second connection ends 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.
• another aspect of the present disclosure includes 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 value of 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 voltage 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 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.
• 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 voltage and 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 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; 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, 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
• Another aspect of the present disclosure is 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 value 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
• a power distribution network state estimation system can estimate the connection direction of a sensor-equipped switch.
• FIG. 1 is a schematic block diagram illustrating the connections of a power distribution grid state estimation system 10 according to an embodiment of the present disclosure.
• 1 is a schematic block diagram showing a configuration of a power distribution network state estimation system 10 according to the embodiment.
• 10 is a graph showing a display example (part 1) of the display unit 15 in the embodiment.
• 10 is a graph showing a display example (part 2) of the display unit 15 in the embodiment.
• 10 is a flowchart illustrating an example of the operation of the power distribution network state estimation system 10 according to the embodiment.
• 10 is a flowchart illustrating an example of the operation of the power distribution network state estimation system 10 according to a modified example of the embodiment.
• FIG. 2 is an explanatory diagram illustrating the hardware configuration of each device according to the embodiment and a modification example.
• FIG. 1 is a schematic block diagram showing the connections 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.
• the 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.
• the measurement value collection system 30 collects measurement values from sensors located within the power distribution network, including sensors equipped in the switches Sa, Sb, and Sc.
• 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 composed of a single device, or may be composed of multiple devices connected via a network or the like.
• Switch Sa (first switch) is a switch with a sensor placed on distribution line Fa (first distribution line) that makes up the distribution network.
• Distribution line Fa is connected to transformer Ta via switch Sa.
• Load center La is the load center of distribution line Fa.
• Switch Sa is normally closed to supply power from transformer Ta to distribution line Fa.
• Switch Sb (third switch) is a switch with a sensor placed on distribution line Fb (second distribution line) that makes up the distribution network.
• Distribution line Fb is connected to transformer Tb via switch Sb.
• Load center Lb is the load center of distribution line Fb.
• Switch Sb is normally closed to supply power from transformer Tb to distribution line Fb.
• switches Sa and Sb measure the voltage and current (active power and reactive power) at each switch and supply these measurement values to the measurement value collection system 30.
• Switches Sa and Sb are normally closed, and the voltages at both ends are equal. Therefore, the voltage measurement value measured by the sensors and supplied to the measurement value collection system 30 may be the voltage at either end of switches Sa and Sb on the transformer Ta and Tb sides or on the distribution line Fa and Fb sides, or it may be the voltage at each end.
• 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.
• 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.
• FIG. 2 is a schematic block diagram showing the configuration of a power distribution network state estimation system 10 in 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.
• the measurement value acquisition unit 11 acquires measurements 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, the voltage Vs (first connection end voltage) at the S end (first connection end) of a switch Sc, one end of which is connected to the distribution line Fa, and the voltage Vt (second connection end voltage) at the T end (second connection end) of the switch Sc.
• These voltage and power flow measurements may be average values for a predetermined period (e.g., one minute) at predetermined intervals (e.g., one minute) for a predetermined time period (e.g., one day). Note that these average values may be calculated from instantaneous values by the measurement value collection system 30 and acquired by the measurement value acquisition unit 11, or may be calculated by the measurement value acquisition unit 11 based on instantaneous values acquired from the measurement value collection system 30.
• 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 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 value indicating the voltage drop (first voltage drop) as the sum of the value obtained by multiplying a preset value Ra indicating the resistance of the distribution line Fa by the active power Pa and the 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).
• 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 be values that vary depending on the time.
• the correlation calculation unit 13 calculates the time correlation (first time correlation) between the value obtained by subtracting the measured value of voltage Vs from the measured value of voltage Va and the value indicating the voltage drop (first voltage drop) calculated by the voltage drop calculation unit 12. The correlation calculation unit 13 also calculates the time correlation (second time correlation) between the value obtained by subtracting the measured value of voltage Vt from the measured value of voltage Va and the value indicating the voltage drop (first voltage drop) calculated by the voltage drop calculation unit 12.
• the determination unit 14 estimates which of the S-terminal and T-terminal is connected to the 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 distribution line Fa. Note that when making the estimation, other conditions may also be used, such as the value of the larger time correlation exceeding a predetermined threshold.
• the connection terminal corresponding to the first time correlation is the S-terminal where the voltage Vs used to calculate the first time correlation was measured
• the connection terminal corresponding to the second time correlation is the T-terminal where the voltage Vt used to calculate the second time correlation was measured.
• 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 make its estimation.
• the display unit 15 displays a message notifying the operator that the connection relationship between the switch Sc and the distribution line Fa is not consistent. Based on this display, the operator can correct the connection relationship between the switch Sc and the distribution line Fa that was stored in the distribution grid state estimation system 10 or the like.
• the message notifying the operator that the connection relationship is not consistent 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.
• This display may be performed using a display provided in the power distribution grid state estimation system 10, or may be performed using a display provided in another device that is communicatively connected to the power distribution grid state estimation system 10.
• Figure 3 is a graph showing an example (part 1) of display by the display unit 15 in this embodiment.
• Figure 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.
• the horizontal axis is the length of the distribution line Fa
• the vertical axis is voltage.
• Sa indicates the position of the switch Sa
• La indicates the position of the load center La
• Sc indicates the position of the switch Sc.
• the solid line graph is a straight line connecting the voltage Va at the switch Sa and the voltage Vs at the switch Sc.
• the dotted line graph is a straight line connecting the voltage Va at the switch Sa and the voltage Vt at the switch Sc.
• the dashed line graph is a line connecting the voltage Va at the switch Sa and the voltage Va - (PaRa + QaXa) at the load center La, and further connecting at the same voltage to the switch Sc.
• These values are values at a certain time, and the operator may be able to set that time, or they may be average values over a specified period.
• Voltage Va - (PaRa + QaXa) indicates the voltage at switch Sc based on the calculated voltage drop. If the connection direction of switch Sc stored by the power distribution network state estimation system 10 is correct, this value is expected to be close to voltage Vs. Therefore, by comparing this value with voltages Vs and Vt, the operator can also confirm (estimate) whether there is an error in the connection direction (S end, T end) of switch Sc stored by the power distribution network state estimation system 10.
• FIG. 4 is a graph showing a second example of a display by the display unit 15 in this embodiment.
• the horizontal axis is PaRa + QaXa
• the vertical axis is 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 pattern will appear in the set of plotted points as shown in FIG. 4; however, if there is no time correlation, no pattern will appear.
• FIG. 4 By referring to the graph in FIG.
• the power distribution network state estimation system 10 can estimate the connection direction of the sensor-equipped switch Sc.
• 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 primary storage medium such as a random access memory.
• the memory H8 may also be cache memory.
• the memory H8 stores instructions when these instructions are executed by one or more processors H9.
• the processor H9 is a CPU (central processing unit).
• the processor H9 may also 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 the instructions stored in the one or more memories H8.
• 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, etc., the terms 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 term control module P.
• One embodiment of the present disclosure provides a power distribution system 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 values of the power flow; and a power distribution system that calculates a voltage drop from the measurement values of the voltage.
• 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.
• Another embodiment of the present disclosure is the power distribution network state estimation system described in (1), wherein the power flow measurement value 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.
• the power distribution network state estimation system can estimate the connection direction of the second switch using the voltage drop calculated from the active power and reactive power at the first switch.
• Another embodiment of the present disclosure is the power distribution network state estimation system described in (1) or (2), 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.
• the power distribution network state estimation system can notify the user of this fact.
• Another embodiment of the present disclosure is a power distribution network state estimation system described in any one of (1) to (3), wherein the measurement value acquisition unit acquires measurement values of 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, 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 value.
• a third time correlation is calculated 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 is calculated 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
• 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.
• the power distribution network state estimation system can estimate the connection direction of the second switch with greater accuracy than (1).
• Another embodiment of the present disclosure includes 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 value of 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 the measured value of the first connection end voltage from the measured value 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 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 at least on the first
• Another embodiment of the present disclosure is a method for estimating a power distribution network state, 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 the 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; calculating a second time correlation between the 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.
• a computer including 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 value of power flow;
• the program functions as 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 determination unit that estimates which of the first and second connection ends is connected to the first distribution line based at least on the first time correlation and the second time correlation
• the power distribution grid state estimation system 10, the centralized voltage control system 20, and the measurement value collection system 30 in Figures 1 and 2 may be realized by recording a 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 on a computer-readable recording medium, and loading and executing the program recorded on this recording medium into a computer system.
• the term "computer system” here includes hardware such as the OS and peripheral devices.
• “computer-readable recording medium” 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 medium” also includes devices that dynamically store programs for a short period of time, such as communication lines 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 computer systems that serve as servers or clients in such cases. Furthermore, the above-mentioned programs may be those that implement some of the functions described above, or may be those that can implement the functions described above in combination with programs already stored in the computer system.

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