Power distribution system status estimation system, power distribution system status estimation method

Abstract

To provide a power distribution system state estimating system and method for estimating a power distribution system state with high precise by conducting a minimum number of calculations.SOLUTION: In a power distribution system estimating system, a state estimation processing unit estimates a state of a power distribution system having a load point n (n≥1) between an arbitrary position r and a power transmission end s of an area K surrounded by a sensor. At least either one of an effective power calculation value PnL' and a reactive power calculation value QnL' or a voltage Vn' current InL' is estimated and calculated on the basis of effective power Ps and reactive power Qs in the power transmission end s obtained from a measurement value data storage unit, effective power Pr and Qr in a sensor mounting position r obtained from the measurement value data storage unit, PnG and QnG in an area obtained from a power generation estimation value data storage unit, "CapaPn" and "CapaQn" for use in proportional distribution obtained from a system facility data storage unit or the measurement value data storage unit, and a line impedance (Rn,Xn) between the sensor mounting position r and the power transmission end s obtained from the system facility data storage unit.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a technique for estimating the state (actual load and voltage) of a power distribution system based on measurement information of a sensor system device (hereinafter abbreviated as a sensor).

Background Art

[0002] In a power distribution system, stable power must always be supplied to meet the ever-changing power demands of consumers. The state of this power distribution system can be grasped by using the measured values sent from a substation and the sensor measurement values.

[0003] At that time, in the power distribution system, the current value and power value measured by the sensor include the line loss consumed by wires and the like, and if divided as it is, the actual load is estimated to be larger than the true value, and there is a possibility that an error will occur between the actual voltage and the calculated voltage.

[0004] When this voltage error becomes large, it also affects the consideration of countermeasures during voltage deviation, making it difficult to keep the voltage within an appropriate range. As a countermeasure, the line loss is estimated based on the calculation result of power flow calculation, and the estimation accuracy is improved by re-estimating the actual load. As one of them, the power distribution system state estimation method of Non-Patent Document 1 is known.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the method of Non-Patent Document 1, when estimating the actual load, the sectional load power obtained by apportioning the power transmitted to the system by the sectional equipment capacity is used as the median value, and the load values in the vicinity thereof are obtained by a heuristic method. However, when using the heuristic method, the number of trials (number of calculations) increases, resulting in an increase in calculation time and a possible inability to achieve prompt response.

[0007] The present invention is made to solve such a conventional problem, and an object thereof is to accurately estimate the state of a distribution system with a small number of calculations.

Means for Solving the Problem

[0008] (1) One aspect of the present invention is a system for estimating the state of a distribution system having n load points (n≧1) between a power transmission end s where sensor system equipment is installed and an arbitrary position r, a first storage unit that stores equipment data of the distribution system, a second storage unit that stores measured value data of the sensor system equipment, a third storage unit that stores an estimated power generation value for the distribution system, a state estimation processing unit that estimates the state of the distribution system, and the state estimation processing unit the active power P G , , G , , r , , s , , n , n , n , n , , r , , s , , , n , and the reactive power Q s obtained from the second storage unit, the active power P r and the reactive power Q r obtained from the second storage unit at the position r, the power generation output P n G , Q n G obtained from the third storage unit within the area, “CapaP n ” “CapaQ n ” used for apportionment obtained from the first storage unit or the second storage unit, the line impedance (R n , Xn )and, Based on this, the calculated active power P of each load point n L’ and the calculated reactive power value Q n L’ or voltage V n 'Current I n L’ It is characterized by estimating and calculating at least one of the two.

[0009] (2) An aspect of the present invention is a first storage unit that stores equipment data of a power distribution system having n load points (n≧1) between a power transmission end s on which sensor equipment is installed and an arbitrary position r, A second storage unit for storing measured value data from the aforementioned sensor system equipment, A third storage unit that stores estimated power generation values ​​for the aforementioned power distribution system, A state estimation processing unit for estimating the state of the power distribution system, A method for performing a power distribution system state estimation system, comprising: In the state estimation processing unit, The active power P of the power transmission terminal s obtained from the second storage unit s and reactive power Q s and, The effective power P at position r obtained from the second storage unit r and reactive power Q r and, Power output P within the area obtained from the third storage unit n G Q n G and, "CapaP" used for apportionment obtained from the first storage unit or the second storage unit. n "CapaQ n "and, The transmission impedance (R) between the transmission end s and the position r, obtained from the second storage unit, is n ,X n )and, Based on this, the calculated active power P of each load point n L’ and the calculated reactive power value Q n L’ or voltage V n'Current I n L’ It is characterized by estimating and calculating at least one of the two. [Effects of the Invention]

[0010] According to the present invention, the estimation of the power distribution system status can be achieved with high accuracy using a small number of calculations. [Brief explanation of the drawing]

[0011] [Figure 1] A diagram showing the configuration of a power distribution system status estimation system according to an embodiment of the present invention. [Figure 2] A chart illustrating the processing steps. [Figure 3] Diagram illustrating an example. [Modes for carrying out the invention]

[0012] The following describes a power distribution system state estimation system (method) according to an embodiment of the present invention. This system estimates the actual load and voltage within the power distribution system based on measurement information from sensors.

[0013] The aforementioned system is composed of a computer and is equipped with the hardware resources of a normal computer (CPU, RAM, ROM, HDD, SSD, etc.). As a result of the cooperation of these hardware resources and software resources (OS, applications, etc.), as shown in Figure 1, the system 1 implements a grid equipment data storage unit 2, a measured value data storage unit 3, a power generation estimated value data storage unit 4, a state estimation processing unit 5, a real load estimation result storage unit 6, and a state estimation result storage unit 7.

[0014] Here, the storage units 2-4, 6, and 7 are built on a computer's memory device. Specifically, storage unit 2 stores the resistance and inductance components of the impedance between each load in the transmission line.

[0015] The storage unit 3 stores the measured values ​​from the sensors, and the storage unit 4 stores estimated values ​​such as the power output within the area surrounded by the sensor group.

[0016] The state estimation processing unit 5 plays a central role in the system 1, taking grid equipment data, measurement data, and power generation estimation data acquired from the storage units 2 to 4 as input, and performs grid state estimation to calculate the actual load estimate and state estimate (voltage and current). The actual load estimate and state estimate calculated here are stored in the storage units 6 and 7, respectively. [Examples]

[0017] Figure 2 shows the processing steps of the power distribution system state estimation method by the state estimation processing unit 5. Here, the state estimation method considering line losses will be explained using the embodiment shown in Figure 3, namely the actual load estimation in area K surrounded by sensors, as an example. Area K in Figure 3 is equipped with sensors at two locations, the transmission end s and the sensor installation position r, and in this sense, s and r can be called sensor installation points. A load L and a generator G are provided at each position (load point) of the lines 1 to n between these two points s and r.

[0018] S01: When the state estimation process starts, the sensor measurement value is set as the initial value of the total load. That is, the initial setting is the total load in area K (P sum Q sum As initial values ​​for ), the measured values ​​at the power transmission end s and the sensor installation position r are set as shown in equations (1-1) to (1-4).

[0019]

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[0020] P *_sum : Active power component of the load (* indicates the sensor installation points for s and r) Q *_sum : Reactive power component of the load (* indicates the sensor installation points for s and r) S02: Estimate the actual load for each sensor area. Here, the total actual load P within area K is used. k Q k We estimate this using equations (2-1) and (2-2).

[0021]

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[0022] In formulas (2-1) and (2-2), “P G ", "Q G This indicates the power output within Area K. This power output value is obtained from the power generation estimation data storage unit 4.

[0023] S03: Allocate the load proportionally. Use "CapaP" for allocation. n "CapaQ n This refers to the ratio of active power to reactive power, and can be expressed as, for example, contract capacity, annual power consumption, monthly power consumption, hourly power consumption, or minute-by-minute power consumption.

[0024] Specifically, "CapaP m (m=0,1,2,...n) "CapaQ m The values ​​(m=0,1,2,...n) are stored in the system equipment data storage unit 2 or the measurement data storage unit 3 in Figure 1 and are acquired when the state estimation method is executed. Here, the active power P of each load is calculated using equations (3-1) and (3-2). n L 'and reactive power Q n L Calculate the ''. The calculated value obtained by proportional calculation is marked with an '' in the upper right corner.

[0025]

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[0026] S04: Perform power flow calculations to determine the voltage, current, active power, and reactive power at each node (load point) in the section from the transmission end s to the sensor installation position r in Figure 3, i.e., between "sr". The specific calculation methods are shown in (1) to (4) below. Here, the calculated values ​​obtained from power flow calculations are marked with an apostrophe ('') in the upper right corner.

[0027] (1) Calculation of node current The node currents of the load L and generator G can be calculated using equations (4-1) and (4-2). In this case, the generator output P n G Q n G This data is obtained from the power generation estimated value data storage unit 4.

[0028]

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[0029] (2) Regression calculation (combination of currents) Here, as shown in equation (5), the currents are combined from the sensor installation position r toward the power transmission end s. In this case, the current flowing into the sensor installation point r is also the current on the load side of the installation point r.

[0030]

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[0031] (3) Forward calculation (voltage calculation) Specifically, as shown in equation (6), the voltage is recalculated using the current obtained by backward calculation from the transmitting end s to the receiving end.

[0032]

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[0033] In formula (6), “R n-1 ", "X n-1This indicates the resistance and inductance components of the impedance between each load in the transmission line, and these values ​​are obtained from the system equipment data storage unit 2.

[0034] (3) Calculation of active power and reactive power Here, as shown in equations (7-1) and (7-2), the apparent power S on the left side of equation (7-1) is calculated using the current and voltage obtained from the backward and forward calculations. n Find the value of ' and the active power P on the right side of equation (7-2). n 'and reactive power Q n Calculate '.

[0035]

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[0036] S05: Re-estimate the load. That is, as shown in equations (8-1) to (8-4), the sum of the load set in S01 (P sum Q sum The loss of the measured value is estimated by subtracting ). Note that the active power P is calculated at the power transmission end s and the sensor installation position r. s ', P r 'and the calculated reactive power value Q s ', Q r ' is calculated by S02.

[0037]

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[0038] Then, as shown in equations (9-1) to (9-4), the measured value (P s ,P r Q s Q r The value obtained by subtracting the aforementioned loss from ) is set as the total load after the sensor.

[0039]

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[0040] S06: The result obtained in S05 is expressed in equations (2-1) and (2-2) as "P k Q k Substitute this into the equation, and then use equations (3-1) and (3-2) to find the actual load (active power P) at each load point. n L’ , reactive power Q n L’ ) is recalculated (S06-1). At this time, the voltage and current values ​​(V) are calculated from the value obtained by subtracting the loss. n '·I n L’ ) may be calculated (S06-2).

[0041] Subsequently, by repeating steps S02 to S05, the calculated active and reactive power values ​​for each load point, assuming line losses (P n L’ Q n L’ This makes it possible to obtain ) with high accuracy.

[0042] This repetition is preferably carried out until the absolute value of the error between the calculated and measured (true) values ​​of active and reactive power at the power transmission end s and the sensor installation position r falls below a threshold (predetermined value), as shown in equations (10-1) and (10-2).

[0043] However, if the pre-set upper limit of the calculations is reached, the process will terminate at that point. It is also possible to configure the system so that the load from S03 and the values ​​of "V" and "I" from S04 are saved as they are after the iterative calculations are completed, without performing the recalculation in S06.

[0044]

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[0045] According to the aforementioned system 1, by performing power flow calculations and repeatedly reestimating (recalculating) the load while considering line losses, it is possible to perform highly accurate estimations with fewer calculations.

[0046] In other words, as mentioned above, the heuristic method in Non-Patent Document 1 uses the median value of the load, so depending on the conditions, the number of trials may increase, and it is conceivable that the calculation time may be long. In this regard, according to System 1, it is only necessary to simply repeat the steps S02 to S05 using the measured values ​​of the power transmission end s and the sensor installation position r, and trials can be performed with less calculation time.

[0047] It should be noted that the present invention is not limited to the embodiments described above, and can be implemented with modifications within the scope of each claim. For example, Figure 3 shows a configuration in which no sensors are installed at any of the load points "1 to n" of the line, but a configuration in which sensors are installed at any of the load points at each of the "1 to n" positions is also possible.

[0048] In this case, the actual load can be estimated by dividing area K at the location where each sensor is installed. For example, if a sensor is installed at load point n, area K can be divided into two areas: from the transmission end s to load point n, and between load point n and sensor installation location r. Estimation calculations are then performed for the portion where no sensor is installed. The active power P at the load point where no sensor is installed. n L’ For estimation calculations such as those mentioned above, the measured values ​​at the load point where the sensor is installed are used instead of the estimated values.

[0049] Furthermore, the present invention can also be applied to sensor values ​​from sensor systems installed only at point s on a power transmission line. In this case, the measured value at point r should be set to "0" and the above formulas should be applied. [Explanation of Symbols]

[0050] 1…Power distribution system status estimation system 2…System equipment data storage unit 3…Measurement data storage unit 4…Power generation estimated value data storage unit 5...State estimation processing unit 6...Actual load estimation result storage unit 7...State estimation result storage unit

Claims

1. A system for estimating the state of a power distribution system having n load points (n≧1) between a power transmission end s where sensor equipment is installed and an arbitrary position r, A first storage unit for storing equipment data of the aforementioned power distribution system, A second storage unit for storing measurement data from the aforementioned sensor system equipment, A third storage unit that stores estimated power generation values ​​for the aforementioned power distribution system, A state estimation processing unit for estimating the state of the power distribution system, Equipped with, The state estimation processing unit, The active power Ps and reactive power Qs of the power transmission terminal s obtained from the second storage unit, The active power Pr and reactive power Qr at position r obtained from the second storage unit, The power generation output PnG and QnG within the area obtained from the third storage unit, "CapaPn" and "CapaQn" used for apportionment obtained from the first storage unit or the second storage unit, The line impedance (Rn, Xn) between the power transmission end s and the position r obtained from the first storage unit, When estimating and calculating the active power value PnL' and the reactive power value QnL' or voltage Vn' and current InL' at each of the load points based on the above, Calculate the track loss amounts "Plus's", "Qloss's", "Plus'r", and "Qloss'r". The total load sum "Ps_sum", "Qs_sum", "Pr_sum", and "Qr_sum" is calculated by subtracting the line losses "Plus's", "Qloss's", "Plus'r", and "Qloss'r" calculated from the measured active and reactive powers "Ps", "Qs", "Pr", and "Qr" at the transmission end s and the arbitrary position r. The difference between the calculated active power values ​​"Ps'" and "Pr'" and the calculated reactive power values ​​"Qs'" and "Qr'" and the measured values ​​from the respective sensor system devices is calculated, and the calculation continues until the absolute value of the calculated difference falls below a predetermined value, or until the upper limit of the number of calculations is reached. The sum of the aforementioned loads, "Ps_sum", "Qs_sum", "Pr_sum", and "Qr_sum", is fed back. The calculation of the active power value PnL' and the reactive power value QnL', or at least one of the voltage Vn' and current InL' for each load point is repeated. A power distribution system status estimation system characterized by the following features.

2. A sensor system is installed at at least one of the n load points. The calculation of at least one of the active power value PnL' and reactive power value QnL', or voltage Vn' and current InL', at a load point where the aforementioned sensor system equipment is not installed, is performed based on the measured values ​​at the load point where the aforementioned sensor system equipment is installed. The power distribution system status estimation system according to claim 1, characterized in that it is as described above.

3. A first storage unit stores equipment data for a power distribution system having n load points (n≧1) between a power transmission terminal s where sensor equipment is installed and an arbitrary position r, A second storage unit for storing measurement data from the aforementioned sensor system equipment, A third storage unit that stores estimated power generation values ​​for the aforementioned power distribution system, A state estimation processing unit for estimating the state of the power distribution system, A method for performing a power distribution system state estimation system, comprising: In the state estimation processing unit, The active power Ps and reactive power Qs of the power transmission terminal s obtained from the second storage unit, The active power Pr and reactive power Qr at position r obtained from the second storage unit, The power generation output PnG and QnG within the area obtained from the third storage unit, "CapaPn" and "CapaQn" used for apportionment obtained from the first storage unit or the second storage unit, The line impedance (Rn, Xn) between the power transmission end s and the position r obtained from the first storage unit, The method includes a step of estimating and calculating the active power value PnL' and the reactive power value QnL' or voltage Vn' and current InL' at each load point based on the above, The aforementioned step is, The steps involve calculating the track loss "Plus's", "Qloss's", "Plus'r", and "Qloss'r", The steps include: calculating the total load sum "Ps_sum", "Qs_sum", "Pr_sum", and "Qr_sum" by subtracting the line losses "Plus's", "Qloss's", "Plus'r", and "Qloss'r" calculated from the measured active and reactive powers "Ps", "Qs", "Pr", and "Qr" at the transmission end s and the arbitrary position r; The difference between the calculated active power values ​​"Ps'" and "Pr'" and the calculated reactive power values ​​"Qs'" and "Qr'" and the measured values ​​from the respective sensor system devices is calculated, and the calculation continues until the absolute value of the calculated difference falls below a predetermined value, or until the upper limit of the number of calculations is reached. A step of feeding back the sum of the aforementioned loads "Ps_sum", "Qs_sum", "Pr_sum", and "Qr_sum", The steps include repeatedly performing the calculation of the estimated active power value PnL' and the reactive power value QnL', or at least one of the voltage Vn' and current InL' at each of the load points, A method for estimating the state of a power distribution system, characterized by having the following features.

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