JP2023010451A - State estimation device, control method for state estimation device and program - Google Patents

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

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

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

JP 2018-085879 A

However, it may be difficult to uniquely determine the state values of the estimation points based on the measured data, such as when the number of measuring instruments is small compared to the number of locations (estimation points) to be estimated in the distribution system. .

The present invention has been made in view of such problems, and even if the number of measuring instruments is smaller than the number of points (estimation points) to be estimated in the distribution system, the state of the distribution system can be estimated. An object of the present invention is to provide a state estimation device, a control method for the state estimation device, and a program.

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

INDUSTRIAL APPLICABILITY The present invention can estimate the state of a distribution system even when the number of measuring devices is smaller than the number of locations (estimation points) to be estimated in the distribution system.

It is a figure which shows the structure of a state estimation apparatus. 3 is a diagram showing the configuration of a storage device; FIG. It is a figure for demonstrating a power distribution system and a state estimation apparatus. It is a figure for demonstrating a power distribution system. It is a figure for demonstrating a power distribution system. It is a figure which shows the functional structure of a state estimation apparatus. It is a flowchart which shows an example of the process performed by a state estimation apparatus.

At least the following matters will become apparent from the descriptions of this specification and the accompanying drawings.
<<<Configuration of State Estimating Device 200>>>

FIG. 1 is a diagram showing the configuration of a state estimation device 200 that is an embodiment of the present invention. State estimating device 200 is a device for estimating the state of distribution system 1000 shown in FIGS. A computer having a device 260 and a recording medium reading device 270 .

CPU 210 realizes various functions of state estimating device 200 by executing state estimating device control program 700 stored in memory 220 or storage device 240 .

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.

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 .

FIG. 2 shows how the state estimation device control program 700 and the system information table 600 are stored in the storage device 240 .

Various functions of the state estimation device 200 are performed 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 being executed or processed by the CPU 210. Realized.

The state estimating device control program 700 is a general term for programs for realizing the functions of the state estimating device 200 according to the present embodiment. ), various libraries, etc.

The system information table 600 is a table that records the configuration of the distribution system 1000, the electrical characteristics of the devices that make up the distribution system 1000, and the like.

The system information table 600 records, for example, data necessary for simulating the distribution system 1000 using equations such as state equations and power flow equations. Although the details will be described later, the state estimation device 200 uses the system information table 600 in a state in which the power flow measurement value of the sensor-equipped switch SW and the active power measurement value of the smart meter SM are acquired. Executes the state estimation process. In the state estimation process, the state of the distribution system 1000 including the section K, that is, the state values of the voltage, current, power, etc. in the distribution system 1000 are obtained.

Returning to FIG. 1, the input device 250 is a device that receives commands and data input by the user, and includes an input interface such as a keyboard and a touch sensor that detects a touch position on the touch panel display.

The output device 260 is, for example, a device such as a display or a printer.

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

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

The sensor-equipped switch SW is arranged at the end of one section K of the distribution system 1000 . That is, the sensor-equipped switch SW divides the distribution system 1000 into a plurality of sections. The sensor-equipped switch SW is a measuring instrument capable of measuring voltage, current and phase, or active power and reactive power at the measurement point (end of section K). In the following, the voltage current and phase or the active and reactive powers measured by the sensored switch SW are collectively referred to as "flow measurements" or "flow measurements".

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

Each consumer serves as a power load. Consumers can include facilities (for example, factories) that consume the power supplied from the distribution line 1200, as well as power generation facilities (not shown) such as inverters that supply power to the distribution line 1200. . Therefore, the distribution line 1200 is connected to equipment that consumes power from the distribution line 1200 and power generation equipment that supplies power to the distribution line 1200 . Here, load is generically referred to regardless of whether it is consumed or supplied.

In addition, a plurality of nodes N are provided in the section K of the distribution system 1000. The nodes N represent each range into which the section K is further divided, and the transformers and distribution lines installed in the section K It is identified by an appropriately defined position on the distribution system 1000, such as a branch point of 1200. In this embodiment, it is assumed that each node N in section K has smart meters SM of one or more consumers.

Hereinafter, the active power measured by the smart meter SM and aggregated at each node N is generically referred to as "active power measurement".

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

Although the power distribution system 1000 includes various other equipment, sensors, and the like, a simplified power distribution system 1000 is shown here as an example for the sake of convenience.

For example, the distribution system 1000 will be described with reference to the example of FIG.

A distribution line 1200 is radially connected to the distribution system 1000 with a distribution substation 1100 as a starting point (sending node). Sensor-equipped switches SW1 to SW5 are installed on the distribution line 1200, and sections divided by these sensor-equipped switches SW1 to SW5 are defined as sections K1 to K4.

However, when the sensor-equipped switch SW is not installed on the terminal side of the distribution system 1000 as in the section K4, the section from the send-side sensor-equipped switch SW to the terminal node is defined.

Also, a node N is defined on the distribution line 1200 . The node N is an aggregation unit managed in units of pole transformers or designated consumers. Measured values from smart meters SM of a plurality of consumers are aggregated for each node N and used for state estimation.

The sensor-equipped switch (SW1 to SW5) measures the voltage, current, and phase at the installation point at a fixed period Ts1 (for example, 1 minute). These measurements are stored in a database (eg, built on storage device 240).

At this time, it is assumed that the voltage, current, and phase can be uniquely converted into active power flow and reactive power flow. treated as

The smart meter SM measures the power consumption (active power) of the consumer at a fixed cycle Ts2 (for example, 30 minutes) for each node (N1 to N12). These measurements are stored in a database (eg, built on storage device 240).

Since the average value of the amount of active power can be calculated by dividing the amount of power used for each period by the measurement period, the measured value from the smart meter SM is treated as the average value of active power.
<<<Function Blocks of Information Processing Apparatus>>>

FIG. 6 is a diagram showing functional blocks of state estimation device 200. As shown in FIG. The state estimation device 200 has functions of a measured value acquisition section 201 , a distribution coefficient acquisition section 202 , a state estimation section 203 and a reactive power calculation section 204 .

Each of these functions is realized by executing the state estimating device control program 700 according to the present embodiment by the hardware of the state estimating device 200 .

The measured value acquiring unit 201 acquires the power flow measured value at the end of the section K of the distribution system 1000 and the active power measured value at a plurality of nodes N within the section K. As described above, in the present embodiment, the measured value acquiring unit 201 acquires the power flow measured value from the sensor-equipped switch SW every minute, and acquires the active power measured value from the smart meter SM every 30 minutes.

The distribution coefficient acquisition unit 202 acquires distribution coefficients representing ratios of reactive power at a plurality of nodes N within the interval K. FIG. For example, the distribution coefficient acquisition unit 202 performs a predetermined data analysis using both or one of the data related to the equipment connected to the plurality of nodes N and the past reactive power measurement data at the plurality of nodes N , to get the distribution coefficients. Details will be described later.

The state estimating unit 203 converts the total value of reactive power in section K into reactive power at a plurality of nodes N using distribution coefficients, and converts the power flow measurement into the first equation configured to be able to estimate the state of section K. By inputting values and active power measurement values, the total value of reactive power in section K and the active power in the plurality of nodes are obtained as the state of the section.

With this aspect, the state estimation apparatus 200 can estimate the state of the distribution system 1000 even when the number of measuring devices is smaller than the number of locations (estimation points) to be estimated in the distribution system 1000. It becomes possible.

For example, even if the state estimating unit 203 does not know the reactive power of each node N in the section K, if the total value of the reactive power in the section K is known, it can be input into the first equation and solved, The state of section K can be estimated.

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

For example, when estimating the state of the distribution system 1000, the state estimation device 200 does not use the active power and the reactive power of each node N as the elements of the state value, but the active power of each node N and the specified Since it is defined as the total reactive power value of the nodes in section K, the degree of freedom with respect to the number of elements of the measured value is restricted, and the state value can be uniquely determined when estimating the state.

Regarding the power line loss, the active power of each node N and the total value of reactive power of all nodes N in the specified section K are treated as state values, and the line loss is calculated by calculating the measured value according to the first equation. Considered state estimation can be performed.

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

In this case, the state estimation unit 203 further calculates a predetermined second equation using the reactive powers at the multiple nodes N within the interval K and the active powers at the multiple nodes within the interval K, The state of section K may be estimated by calculating the voltage value at node N. FIG.

According to this aspect, the state estimation device 200 can estimate the state of a location (estimation point) in the distribution system 1000 at which estimation is desired.

A more detailed description will be given with reference to FIG.

FIG. 3 shows that the state estimating device 200 acquires the voltage, current, and phase measured values (power flow measured values) at regular intervals (for example, one minute) from the sensor-equipped switch SW, and the power usage from the smart meter SM. Obtain the measured value (active power measured value) for a period (for example, 30 minutes), obtain the system information table 600 (system equipment data) stored in the database in the storage device 240, and use the first equation to calculate the power flow By performing calculations, a pre-defined active power value for each node N and a pre-defined reactive power total value for nodes in a section K are estimated as the state of the distribution system 1000 (state estimation 1).

In addition, the state estimation device 200 uses a distribution model (distribution coefficient) for each section K of reactive power, and deploys the total reactive power value in the section K to each node N, so that the active power of each node N and By obtaining the reactive power and inputting them into the power flow calculation using the second equation, the voltage distribution at each node N is estimated (state estimation 2).

In this way, the state estimation device 200 according to the present embodiment uses the voltage, current, and phase of the sensor-equipped switch SW installed on the distribution system 1000 and the amount of electric power from the smart meter SM of the consumer as measured values. , the load capacity of the distribution system 1000, the power supply capacity including solar power generation, line data, transformer data, etc., using the system configuration data (system information table 600) to determine the voltage at unmeasured points in the distribution system 1000. , the current (tidal current) is estimated periodically.

The state estimating unit 203 may calculate the first equation after multiplying the power flow measurement value and the active power measurement value by a weighting factor that is determined so that the weight becomes smaller as the measurement period becomes longer. .

In other words, in the present embodiment, the power flow measurement value can be obtained in a 1-minute period, and the active power measurement value can be obtained in a 30-minute period. is multiplied by a small weighting factor before calculating the first equation.

With such a mode, it is possible to reduce the degree of influence on the state estimation result with respect to measured values with a slow measurement cycle, and to perform state estimation with higher accuracy.

In addition, the state estimating unit 203 calculates the first equation using the latest power flow measurement value and active power measurement value every predetermined period (for example, every minute) to obtain the reactive power in section K of the distribution system 1000. and active powers at a plurality of nodes N in section K may be repeatedly calculated.

Such an aspect makes it possible to always estimate the latest state of the distribution system 1000 .
<<<Details of processing>>>

A first specific example of state estimation processing executed by state estimation device 200 will be described using the processing flow of FIG.

The state estimating device 200 collectively models the section K of the entire distribution system 1000 and performs calculations. do.

A distribution system 1000 shown in FIG. 5 includes two switches SW with sensors, two nodes N, and one section K. Each node N and the switch SW with sensors are connected by a distribution line 1200. It is

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

Physical quantities shown below use normalized pu units. A discretized value is used for the time t.

At this time, the overall measured value yt at time _t is given by the following equation (3).

However, the measurement cycle is 1 minute for the switch SW with sensor, 30 minutes for the smart meter SM, and 1 minute for the state estimation calculation cycle.

Therefore, the measured value from the sensor-equipped switch SW is updated every calculation cycle, but the measured value from the smart meter SM is not updated during the 30 calculations, and a constant value is used.

For example, L is created as in (6) below.

Therefore, the reactive powers of node N1 and node N2 are expressed as (8).

The state estimating device 200 performs parameter adjustment using, for example, facility-related data such as the capacity of the load facility in the distribution system 1000, the capacity of the photovoltaic power generation facility, and the power contract form, and past measurement data of reactive power. A distribution coefficient is determined by data analysis (S1020).

where H is the linearization matrix of h. At this time, when F=HL, the state equation F (first equation) becomes (12) below. In this way, the state equation F includes distribution coefficients, and is configured so that the total value of reactive power in interval K can be converted into reactive power at a plurality of nodes N. FIG.

Therefore, if the measurement cycle of the sensor-equipped switch SW is set as the calculation cycle for state estimation, there is a period during which the measured value from the smart meter SM is not updated. Can not.

Regarding the weight, the weight of the measured value from the switch SW with sensor is compared with the weight of the measured value from the smart meter SM, and the weight of the measured value from the smart meter SM is reduced. value can be less affected.

As a result, even while the measured value from the smart meter SM is not updated, the variation can be reflected in detail in the state value using the measured value from the sensor-equipped switch SW.

The state estimating device 200 determines a specific value of the weight by performing an analysis or the like by simulating state estimation using past measurement value data.

For example, when the state estimation device 200 applies the least squares method as the state estimation method, the state estimation device 200 obtains the state value by the following equation (15).

As the state estimation method, various state methods such as the successive least squares method and the Kalman filter can be applied.

とし、状態値を各ノードＮ１、Ｎ２の有効電力と無効電力に展開し、各ノードＮ１、Ｎ２の有効電力と無効電力の値から、各ノードＮ１、Ｎ２の電圧（振幅、位相）を出力する潮流方程式（第２方程式）によって潮流計算を行い、各ノードＮ１、Ｎ２の電圧を計算することができる（Ｓ１０４０）。

, the state values are developed into the active power and reactive power of each node N1, N2, and the voltage (amplitude, phase) of each node N1, N2 is output from the values of the active power and reactive power of each node N1, N2 A power flow calculation can be performed according to the power flow equation (second equation) to calculate the voltages of the nodes N1 and N2 (S1040).

In this embodiment, an example of estimating the state of a single interval K is shown, but even when estimating the state of a plurality of intervals K, the state values can be estimated by similar calculations.

Next, a second specific example of state estimation processing performed by state estimation device 200 will be described.

In this embodiment, a measurement value vector composed of a measurement value (power flow measurement value) from the sensor-equipped switch SW (power flow measurement value) and a measurement value (active power measurement value) from the smart meter SM is defined and set in advance. Define a state value vector composed of the active power of multiple nodes N and the total value of reactive power of multiple nodes N in a preset interval K, and use the state value vector to determine the value of the measurement point Define a state equation (first equation) that calculates

However, the measured values from the sensor-equipped switches SW are assumed to be actual measured values (for example, voltage, current, phase), and the values are converted into voltage, active power flow, and reactive power flow. In addition, the measured value from the smart meter SM is assumed to be the amount of power used, and the value is converted into the average active power value. In addition, the measured values from the smart meters SM are aggregated in preset node units and given to the measured value vector.

The weight matrix W is a matrix having weight vectors w as diagonal elements, as shown in (22) below.

If the weights were all 1, then the state value would be calculated if all measurements were considered equally. However, the sensor-equipped switch SW and the smart meter SM have different measurement cycles, and generally the measurement value from the smart meter SM has a slower measurement cycle. When calculating the state estimation according to the measured value with a short measurement period, the measured value with a long measurement period is given the value before updating as the measured value until the value is updated.

In addition, the measured value from the smart meter SM is a value obtained by converting the power amount into an average value of active power, and further includes a time delay factor. Therefore, when the state is estimated in accordance with the measurement cycle of the sensor-equipped switch SW, the data measured by the smart meter SM is considered to have low reliability.

In consideration of these, the value of the weight vector related to the smart meter SM is compared with the value related to the sensor-equipped switch SW and a small value is given, thereby weakening the degree of influence of the measurement value of the smart meter SM on the state estimation. It is possible to reflect the variable factors mainly related to the node active power in the state value.

The state estimation device 200 sets a weight vector in advance by performing analysis using past data, and performs state estimation.

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

When the matrix L is used, the linearized power flow equation is expressed as (26) below.

The state estimating device 200, the control method of the state estimating device 200, and the program 700 according to the present embodiment have been described above in detail. It is possible to estimate the state of the distribution system 1000 even when the number of measuring instruments is smaller than the number of the .

The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit and interpret the present invention. The present invention may be modified and improved without departing from its spirit, and the present invention also includes equivalents thereof.

For example, in addition to independent state estimation methods for each time section, such as the least-squares method, weighted least-squares method, and load-corrected state estimation method, this method can also be applied to state estimation methods that perform sequential processing in time series, such as the Kalman filter. Application of the invention is possible.

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 reader 500 network 600 system information table 700 state estimation device control program 800 recording medium 1000 distribution system 1100 distribution substation 1200 distribution line SW switch SM with sensor Smart meter N Node K Section

Claims (7)

A state estimating device for determining the state of a section configured with a plurality of nodes in a 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 a distribution coefficient representing a ratio of reactive power at the plurality of nodes;
In a first equation configured 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, the power flow measurement value and the a state estimating unit that obtains the total value of reactive power in the section and the active power in the plurality of nodes as the state of the section by inputting the active power measurement value;
A state estimator comprising: The state estimation device according to claim 1,
a reactive power calculation unit that calculates reactive power at the plurality of nodes using the total value of reactive power in the section and the distribution coefficient;
with
The state estimating unit further calculates the voltage values at the plurality of nodes by calculating a predetermined second equation using the reactive powers at the plurality of nodes and the active powers at the plurality of nodes. obtained as the state of the interval,
State estimator. The state estimation device according to claim 1 or 2,
The state estimator calculates the first equation after multiplying the power flow measurement value and the active power measurement value by a weighting factor that is determined such that the longer the measurement period, the smaller the weight.
State estimator. The state estimation device according to any one of claims 1 to 3,
The distribution coefficient acquisition unit obtains the distribution coefficient by performing a predetermined data analysis using at least one of data related to equipment connected to the plurality of nodes and past measurement data of reactive power at the plurality of nodes. to get the
State estimator. The state estimation device according to any one of claims 1 to 4,
The state estimating unit calculates the first equation using the latest power flow measurement value and the active power measurement value for each predetermined period, thereby obtaining the total value of reactive power in the section and the plurality of Iteratively calculating the active power at the node and
State estimator. A control method for a state estimation device for estimating the state of a section configured with a plurality of nodes in a distribution system, comprising:
The state estimation device
obtaining power flow measurements at the ends of the section and active power measurements at the plurality of nodes;
Obtaining a distribution coefficient representing a ratio of reactive power at the plurality of nodes;
In a first equation configured 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, the power flow measurement value and the Obtaining the total value of reactive power in the section and the active power in the plurality of nodes as the state of the section by inputting the active power measurement value;
A control method for the state estimator. A computer that estimates the state of a section configured with multiple nodes in a distribution system,
obtaining power flow measurements at the ends of the interval and active power measurements at the plurality of nodes;
obtaining a distribution coefficient representing a ratio of reactive power at the plurality of nodes;
In a first equation configured 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, the power flow measurement value and the a step of obtaining the total value of reactive power in the section and the active power in the plurality of nodes as the state of the section by inputting the active power measurement value;
program to run the

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