JP2018057096A - Power system characteristic estimating device and method, and power system managing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power system characteristic estimating device and method and a power system managing apparatus, in which parameters of a voltage drop expression for a feeding side and a load point can be estimated with precision.SOLUTION: A power system characteristic estimating device comprises: input means for inputting a signal related to a power system; calculation means for calculating, as a solution, an unknown number included in a calculation expression related to the power system by substituting the signal inputted to the input means into the calculation expression; determination means for determining the presence of the solution of the calculation expression from the signal inputted to the input means; and output means for outputting the solution calculated by the calculation means and the determination result by the determination means.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power system characteristic estimation apparatus and method for estimating a state of a power system, and a power system management apparatus.

  The power system is a large-scale system constructed by combining many devices and control methods for stable power supply. The state of the power system can be expressed by physical quantities such as voltage, current, power, frequency, etc., and these states have a surface spread along the system configuration and are accompanied by changes over time. In addition, since the system state changes greatly depending on the power generation and load connected to the power system, various control devices and control methods are used to maintain the steady state.

  There are many factors that cause the electric power system to deviate from the steady state. However, as a change that has occurred in the electric power system in recent years, there has been the introduction of renewable energy. For example, solar power generation and wind power generation are characterized in that the power generation amount is affected by weather conditions by being interconnected in a distributed manner compared to conventional generators. Then, when the generated electric power flows into the power system, changes in the system state such as occurrence of power flow inversion (reverse power flow) and voltage fluctuation occur.

  For example, fluctuations in the amount of power generated by renewable energy may cause the voltage of a line connected to voltage fluctuations to fluctuate, and deviate from the upper and lower limits of the voltage. In order to optimize the voltage by installing the voltage regulator, it is necessary to correctly grasp the state and characteristics of the power system. Here, the state of the power system is a physical quantity of a phenomenon occurring in the power system such as voltage and current, and the characteristic indicates a numerical value, a parameter, etc. associated with the power system equipment configuration such as a line impedance. However, in the present invention, the two may be used without distinction.

  In the power system, there are active discontinuous state changes such as device control, system configuration switching, and generator on / off as discontinuous state changes, while accidents occur as passive discontinuous state changes. Occurs. Accidents that interfere with power supply may occur. Reduction of the power outage range at the time of an accident and shortening of the recovery time are indispensable requests for improving supply reliability.

  By the way, with recent progress of information communication technology, it has become possible to transmit data at high speed. Therefore, a technique is widely used in which sensors are installed in the power system and sensor measurement signals of the power system are utilized. For example, sensor switches, PMUs (Phaser Measurement Units), etc., frequently sample state values such as voltage, current, and phase, and transmit them to the server at the master station using transmission methods such as power line carrier technology and optical cables. To do. In addition to physical quantities such as power flow, technologies have been proposed to analyze the state and characteristics of the power system, such as detecting accidents that occur in the system, estimating the cause of the accident, and locating the accident (estimating the location where the accident occurred). Yes.

  However, since the sensor switch and PMU installation locations and the types of signals that can be collected are limited, it is not possible to measure any state at any location. In view of this, a method has been proposed for estimating the system state and characteristics at appropriate locations from the measurement signals that can be acquired.

  As prior arts related to these points, Patent Document 1 states that “in order to estimate power system impedance, active power and reactive power are output to a connection point with an existing power system that supplies power to a load. The voltage of the interconnection point when the reactive power is intentionally changed and the active power and reactive power are sequentially detected in time series, the voltage fluctuation of the interconnection point voltage, the load power consumed by the load, Couplings obtained by substituting voltage variation, active power and reactive power of the interconnection point voltage detected for a plurality of time-series into a relational expression consisting of power system impedance (R + jX) of the existing power system The configuration of “estimating the power system impedance (R + jX) by solving an equation” is disclosed.

  Patent Document 2 states that “based on measurement data corresponding to sensor voltage measurement data, SVR output voltage Vsvr, SVR passing active power Psvr, and reactive power Qsvr, first, the voltage of the analysis target node of the distribution system within the analysis target period. By calculating the ideal output voltage Vs of the automatic voltage regulator that falls within the upper and lower limit value range, and then performing a multiple regression analysis on the correlation between this ideal value Vs and the measured value of the electrical quantity of the distribution system, The configuration of “determining the setting parameter of the automatic adjuster” is disclosed.

JP 2006-230050 A JP 2010-220283 A

  The conventional techniques disclosed in Patent Document 1 and Patent Document 2 described above are characterized by estimating impedance that is a characteristic of the power system. However, both are technologies developed before the introduction of renewable energy, and do not take into account the phenomenon caused to the power system by the introduction of renewable energy. Specifically, there are voltage fluctuations caused by distributed power sources (power generation), changes in the distribution range of active power and reactive power, changes in load points due to power source and load fluctuations, and the like. The prior art using linear approximation causes an error due to a large change in state due to the introduction of renewable energy.

Specifically, Patent Document 1 prepares a relational expression in a linear form, which includes a voltage fluctuation of the interconnection point voltage, a load power P + jQ consumed by the load, and a power system impedance R + jX of an existing power system. However, there are the following problems in applying this method.
(1) In this method, an impedance calculation formula is expressed in a linear format. However, the approximation error becomes obvious due to the large change in state caused by the introduction of renewable energy.
(2) In order to put this method into practical use, it is necessary to intentionally change the active power and reactive power, which incurs equipment costs and operational costs, and gives them to other customer equipment by changing them. The impact must be taken into account. Moreover, it is not practical to install such a new device for all the lines for which impedance is to be estimated.

Document 2 discloses a technique for calculating line impedance by performing regression analysis of a measurement signal. According to the literature, a three-dimensional space is prepared with active power P and reactive power Q on the bottom two axes, and a sending voltage V on the vertical axis, and the measurement signal is plotted on the space. When a plane is created by regression analysis, the inclination corresponds to resistance R in the active power P-axis direction and reactance X in the reactive power Q-axis direction. This document is characterized by having a coordinate axis of active power P and reactive power Q so as to be able to cope with an arbitrary power factor and improving accuracy by regression analysis as compared with the prior art. However, the following issues become apparent with this method as the introduction of renewable energy increases.
(3) Conventionally, since the range of distribution of active power P and reactive power Q is limited as long as the devices connected to the grid need only handle consumption, such a linear approximation may hold. However, due to the introduction of renewable energy, device consumption and power generation are handled, and the distribution of active power P and reactive power Q is widened, so errors due to linear approximation cannot be ignored.
(4) This method assumes that the load point is constant. Here, the load point is a connection point of a virtual load obtained by reducing the load device and the power generation device connected to the line, and the point is indicated by the line impedance from the sending side. However, the introduction of renewable energy introduces equipment consumption and power generation, and the load point changes over time as the amount of power generated by introducing renewable energy increases. For this reason, the method based on the regression analysis cannot cope with the change of the load point and causes an error.

  As described above, the above-described conventional technique is a technique for a power system before the introduction of renewable energy, and does not consider the phenomenon that occurs in the power system due to the introduction of renewable energy. For this reason, when applied to a recent system in which the system state largely fluctuates due to the introduction of renewable energy, the error becomes large and the practicality is inferior.

  In view of the above, an object of the present invention is to provide a power system characteristic estimation apparatus and method, and a power system management apparatus that can accurately estimate the voltage drop type parameters of the sending side and the load point.

  In order to solve the above problems, the device of the present invention is an input means for inputting a signal related to the power system, and a calculation for substituting the input signal of the input means into a calculation formula related to the power system and calculating an unknown contained in the calculation formula as a solution. Means for determining the presence of a solution of the calculation formula from the input signal of the input means, and output means for outputting the solution calculated by the calculation means and the determination result of the determination means.

  The apparatus of the present invention also includes an input means for inputting a signal related to the power system, a calculation means for substituting the input signal of the input means for a calculation formula related to the power system, and calculating an unknown contained in the calculation formula as a solution. Interpolating means for interpolating or extrapolating the output, determining means for determining the presence of the solution of the calculation formula from the input signal of the input means, switching means for switching the output of the calculating means and the interpolating means using the determination result of the determining means, switching means Output means for outputting the switching result and the determination result of the determination means.

  The method of the present invention inputs a signal related to the power system, substitutes the input signal into a calculation formula related to the power system, calculates an unknown contained in the calculation formula as a solution, and solves the calculation formula from the input signal. It is characterized in that the existence of the image is determined, and the calculated solution and the determination result are output.

  The method of the present invention inputs a signal related to the power system, substitutes the input signal into a calculation formula related to the power system, calculates an unknown contained in the calculation formula as a solution, and solves the calculation formula from the input signal. Is determined, the solution is interpolated or extrapolated to obtain an interpolation value, the determination result is used to switch between the solution and the interpolation value, and the switching result, the solution, and the determination result are output.

  The device according to the present invention is a power system characteristic estimation device that estimates the state of a load point of a power system from the amount of electricity of the power system obtained at a measurement point of the power system. Input means for input, calculation means for substituting the quantity of electricity into a calculation formula related to the power system and calculating an unknown quantity contained in the calculation formula as a solution, interpolation means for interpolating or extrapolating the output of the calculation means, power system for power flow Based on the quantity of electricity, the determination means for determining the existence of the solution of the calculation formula, the switching means for switching the output of the calculation means and the interpolation means using the determination result of the determination means, the switching result of the switching means and the determination result of the determination means are output. Output means is provided.

  The present invention is also a power system management device including a voltage adjustment device that is installed in the power system and adjusts the voltage on the load point side, and the voltage adjustment device is a voltage between the installation point and the load point side. The descent is controlled in accordance with a given line impedance settling value, and the line impedance settling value is given from the output means of the power system characteristic estimation device.

  Further, the present invention is a power system management device including a protective relay device that is installed in a power system and measures a line impedance on a load point side to give a protective output of the power system, and the line impedance of the protective relay device is The power system is provided by the output means of the power system characteristic estimation device.

  According to the present invention, there is an effect that the voltage drop type parameters of the sending side and the load point can be accurately estimated.

  Moreover, according to the Example of this invention, there can exist the following effects. For example, it is possible to detect the tidal current inversion that occurs due to the introduction of renewable energy, and to determine whether or not the above estimation calculation can be calculated when the tidal current is reversed, thereby determining the validity of the calculation result. In addition, there is an effect that the power state at the load point can be accurately estimated from the power state measured on the sending side. Further, there is an effect that the control parameter of the power adjustment device can be calculated based on the result of accurately estimating the power state of the load point from the power state measured on the sending side. Further, the position of the accident point can be estimated by regarding the accident point in the system as a load point and calculating the distance to the load point by the line impedance. Moreover, there is an effect that the load type can be estimated by statistically determining the result of accurately estimating the power state of the load point from the power state measured on the sending side.

The figure which shows the basic composition of the electric power system which this invention makes object. The figure which shows the structural example of the characteristic estimation apparatus of the electric power grid | system which concerns on Example 1 of this invention. The figure which shows the specific example of electric power flow reversal. The figure which shows the determination method of electric power flow inversion. The figure which shows the method of determining using the change of a time positive / negative sign. The figure which shows the method of calculating the time of zero crossing by interpolation. The figure which shows the example which displayed the value of the impedance at that time, and the determination result on the display screen in the form of a table corresponding to each time. The figure which shows a line impedance characteristic. The figure which showed three cones of the line impedance characteristic made at 3 time. The figure which showed the two-dimensional cross section by an impedance about three cones made at 3 time. The figure which shows typically the case where an intersection is obtained on the two-dimensional cross section by impedance about three cones. The figure which shows typically the case where an intersection cannot be obtained on the two-dimensional cross section by impedance about three cones. The figure which shows the structural example of the characteristic estimation apparatus of the electric power grid | system which concerns on Example 2 of this invention. The flowchart which shows the process sequence of this invention. The figure which shows the voltage drop characteristic of an electric power grid | system. The figure which shows the voltage optimization apparatus of an electric power grid | system. The figure which shows the structural change of the electric power system at the time of an accident. The figure which shows the clustering process using an estimation result.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The following examples show specific examples of the contents of the present invention, and the present invention is not limited to these examples, and those skilled in the art within the scope of the technical idea disclosed in this specification. Various changes and modifications can be made.

  Moreover, although this invention has demonstrated the implementation structure about the single phase system | strain, it cannot be overemphasized that it can apply to arbitrary systems, such as a 3 phase system | strain.

  FIG. 1 is a diagram showing a basic configuration of a power system targeted by the present invention.

  The power system is made up of complex combinations of lines and equipment, but it is convenient to focus on the basic configuration in order to analyze the phenomena that occur in the power system. There is also a method of analyzing the entire power system by a method called power flow calculation, but many phenomena can be explained by dealing with the basic configuration. In FIG. 1 showing the basic configuration of the power system targeted by the present invention, it will be treated as a model of one machine and one load.

  In FIG. 1, Node S represents a power supply side, and Node R represents a load point. In the present invention, the resistance R and reactance X, which are line impedance Z, are estimated as the state of the power system between these two points. To do. In FIG. 1, P represents active power, Q represents reactive power, subscript S represents active power P and reactive power Q on the sending side, and subscript r represents active power P and reactive power on the load side. Q is represented.

  FIG. 2 is a diagram illustrating a configuration example of the power system characteristic estimation apparatus according to the first embodiment of the present invention. The power system characteristic estimation apparatus 100 is realized by a program by a computer or the like, but is described here for each main function.

  In FIG. 2, 101 is an input means, and various electric quantities measured by a measuring device (for example, sensor switch, PMU (Phaser Measurement Unit), etc.) on the power delivery side (Node S) of FIG. Input as an attached measurement signal. Specific examples of the amount of electricity include voltage, current, power factor, active power P, reactive power Q, and the like. These electric quantities may be directly measured using the sending side as a measurement point, or may be obtained indirectly from other electric quantities. In the calculation means 102, measurement signals at a plurality of times are combined to calculate, for example, one or more of line impedance (R, X), voltage drop amount, phase difference angle as a load side state. The calculation result is output using the output unit 103 and used for presentation to the operator, log recording, and the like.

  Here, the present invention is a new addition of the determination unit 104, and the determination unit 104 is used to determine whether the calculation unit 102 can perform the calculation or the validity of the calculation result. For this purpose, the determination unit 104 uses an input related to a tidal current among the inputs measured by the input unit 101. The input relating to the power flow is, for example, current I, active power P, reactive power Q, and the like.

  The power system characteristic estimation apparatus 100 shown in FIG. 2 basically includes “a means 101 for inputting a signal related to the power system, and an input signal of the input means 101 is substituted into a calculation formula related to the power system and is included in the calculation formula. A calculation unit 102 that calculates an unknown as a solution, a unit 104 that determines the presence of a solution of the calculation formula from an input signal of the input unit 101, a solution calculated by the calculation unit 102, and a determination result of the determination unit 104 are output. The power system characteristic estimation apparatus characterized by comprising means 103 ”.

  As described above, the present invention is characterized in that the determination unit 104 is used to determine whether the calculation unit 102 can perform the calculation or the validity of the calculation result. Specific processing contents in the means 104 will be described in detail below.

  Returning again to FIG. In FIG. 1, when the voltage at the sending side (Node S) is Es, the voltage at the load point (Node R) is Er, the line impedance is Z, and the current is I, the voltage drop between the two is expressed by equation (1). Can be expressed as

Here, Z = R + jX, R is a resistance, X is a reactance, and j is an imaginary symbol. Further, the active power P, reactive power Q, and voltage Es on the delivery side are in the relationship of the following equation (2). The symbol “ ^* ” represents conjugate. Further, in the figure, Ps and Qs are used by using a subscript S for distinguishing the sending side. However, since all the following explanations show the sending side, they are indicated by P and Q. In addition, it can also be described using a state value on the load side.

  Heretofore, in order to handle the relational expression in a simple manner, it is possible to make an approximate expression based on appropriate assumptions such as whether the resistance R, which is the real part of the line impedance Z, is sufficiently small, or the change in the phase difference angle is sufficiently small. There were many. However, when the state of the power system changes greatly due to the introduction of renewable energy, the error due to these approximations cannot be ignored.

  Therefore, the present invention uses (1) and (2) without approximation. If the resistance R and reactance X are solved, the following equation (3) is obtained. Here, φ indicates a phase difference angle. The equation (3) for determining the resistance R and the reactance X can be rewritten in various ways. In any case, the denominator is the current (current I, active power P, reactive power Q, etc.). It means size.

  Many loads and power sources are linked to the actual power system, but by considering it as one load virtually, it is reduced to the basic configuration as described above, and the power is related to the relationship between the sending side and the load point. It is convenient to analyze system phenomena. Here, if there are measurement signals for the sending side and the load point, the relational expression can be solved. For example, if only the measurement signal for the sending side is available, there are too many unknowns to solve.

  In general, the load of a power system or the magnitude of power generation changes from moment to moment, and the state of the power system changes accordingly. The present invention is characterized in that a simultaneous equation is created using measurement signals at a plurality of times by utilizing the fact that there is a temporal change in the system state. The solution of simultaneous equations is known and often a general software package is available. However, when applied to a power system, the present invention is characterized by detecting a phenomenon that occurs in the power system, paying attention to the fact that a reasonable solution may not be obtained without considering the phenomenon that occurs in the power system. And

  As a phenomenon that occurs in the electric power system that has become apparent through the introduction of renewable energy in recent years, there is the occurrence of tidal current reversal (reverse power flow). This refers to the situation where the direction of power flow reverses. In the process of reversing the tidal current, a point in time when the tidal current becomes zero (zero cross) occurs. At this time, since the relational expression (3) has a power flow (active power P, reactive power Q) in the denominator, the solution does not converge, cannot be calculated, or a solution with a large error can be obtained. And a reasonable solution cannot be obtained.

  Therefore, the present invention is characterized by comprising means for determining whether simultaneous equations can be solved, whether an appropriate solution can be obtained, in other words, whether a measurement signal is valid. This means is the determination means 104 in FIG.

  Fig. 3 shows a specific example of tidal current reversal. Time is plotted on the horizontal axis, current is plotted on the vertical axis, and the current reverses from positive to negative over time, and then returns to positive again. Show. This example shows an example of tidal current reversal between night and day.

  There are several possible definitions of tidal current reversal (reverse power flow). For example, changes in the sign of measurement signals such as current and power can be used. When a current measurement signal is obtained as illustrated in FIG. 3, it is possible to detect when the current sign (flowing direction) is reversed as the occurrence of power flow reversal. Alternatively, when the sign of the active power P is reversed, it can be detected as a power flow reversal. Since these measurement signals change continuously, the sign is inverted via a magnitude of zero. Therefore, detecting sign inversion is often equivalent to detecting a zero crossing of a signal. The present invention detects tidal current inversion in order to determine that calculation is impossible, and does not limit these definitions.

  The present invention considers the following properties to detect and use tidal current inversion. First, the real part and the imaginary part change independently, as can be seen by describing the power relational expression in complex numbers. For example, for the active power P and the reactive power Q, the former is a real part and the latter is an imaginary part. When the sign of the active power P is inverted, the reactive power Q may not always be inverted. Therefore, when the sign of either the real part or the imaginary part is reversed, it is determined that the power flow is reversed.

  The present invention also takes into account the characteristics of the measuring instrument. Although the measurement signal passes through 0 in the process of inverting the sign of the signal, the zero cross may not be detected correctly depending on the measurement device. One reason is that a signal near 0 cannot be amplified correctly due to nonlinearity of the semiconductor element. In addition, there are characteristics such as an offset (displacement from 0) of a measuring device, a quantization number (signal size resolution), and a sampling rate (number of samples / second). Due to these characteristics, even if the measurement object is zero-crossed, 0 may not be output correctly as a measurement signal, and an output signal having a magnitude close to 0 may be obtained. Since these measurement signal errors affect the existence and error of the solution of the calculation formula using the measurement signal, the determination conditions are set in consideration of the device characteristics.

  The present invention is characterized by comprising a determination means 104 relating to the existence of a solution of a calculation formula using a measurement signal, whether or not calculation is possible, or the accuracy of a calculation result. This determination means 104 is not necessary in the electric power system where the phenomenon of tidal current inversion does not occur, and is newly devised and adopted in the present invention in order to cope with the problems caused by the recent introduction of renewable energy. It is.

  A configuration example of the determination unit 104 is shown below. When the input signal is current I and the threshold value used for determination is T, the absolute value | I | FIG. 4 is a diagram showing a method for determining the power flow inversion, and shows the relationship between the input signal and the determination result.

  Equation (4a) shows the logic for expressing this determination equation.

  Equation (4a) determines that calculation is impossible (or a solution cannot be obtained or accuracy deteriorates) when the absolute value of the current I is smaller than the threshold value T. The setting of the threshold value T is determined in consideration of the fact that the smaller the value, the more easily affected by the characteristics of the measuring device, and the larger the value, the more non-computable area is expanded.

  The equation (4a) can be rewritten several times, and may be, for example, the equation (4b). Equation (4b) is determined to be calculable when the absolute value of the current I is larger than the threshold value T.

  Further, using the active power P instead of the current I, the equation (4a) can be realized by the equation (4c). Equation (4c) determines that the calculation is not possible (or the solution cannot be obtained or the accuracy deteriorates) when the absolute value of the active power P is smaller than the threshold value T.

  In addition, although the example which determines using an absolute value was shown here, it cannot be overemphasized that a measurement signal can be determined separately about positive / negative. A composite condition in which a plurality of signals are combined may be used. The threshold value T may be variably set.

  The above is the determination of the size using the threshold value T, but it can be determined by using the temporal change of the sign. FIG. 5 is a diagram illustrating a method for making a determination using temporal changes in the sign. In FIG. 5, when a current as a measurement signal is input as a time-series signal at times t1, t2, t3, and t4, it is detected that the sign of the signal has been inverted at adjacent times, and occurrence of tidal current inversion is determined. To do. In the case of FIG. 5, the sign changes between negative, negative, indefinite, and positive at times t1, t2, t3, and t4. Therefore, it can be determined that the sign is inverted between times t2 and t4 and the power flow is inverted. .

  Since many measurement devices capture measurement signals at every sampling interval (cycle), there are cases where positive and negative measurement signals straddling the zero cross may be obtained instead of the moment when the measurement signal zero crosses. In that case, the time of zero crossing can be calculated by interpolation (or extrapolation) using measurement signals other than zero crossing.

  FIG. 6 is a diagram illustrating a method for calculating the time of zero crossing by interpolation. In FIG. 6, when the values at times t1, t2, t3, and t4 are referenced, zero crossing is performed between times t2 and t3. From this, for example, from time t2, t3 and the magnitude at this time, zero crossing is performed by linear interpolation. T24 can be estimated as the time to perform.

  FIG. 7 shows an example in which the impedance value at that time and the determination result are displayed in a tabular form on the display screen corresponding to each time. Further, the display on the display screen may be displayed in time series together with the validity / invalidity determination results as shown in FIG. 5, or may be displayed together with the interpolation result information as shown in FIG. As described above, the present invention is characterized in that the determination result is displayed on the screen for the operator of the power system as shown in FIG. Similarly, the present invention is characterized by comprising output means for displaying the validity of a calculation result (logic such as pass / fail or number such as accuracy) or recording it as a log of the calculation result. .

  As shown in FIG. 7, the determination result can be used as a switching signal for changing a calculation procedure of generating a signal by interpolation (or extrapolation) when calculation is impossible. . Alternatively, as shown in FIG. 6, measurement signals that can be calculated can be distinguished as valid and invalid. Using this result, simultaneous equations that can be calculated by selecting a plurality of effective measurement signals can be created.

  When the zero crossing of the current is detected, the voltage drop from the sending side to the load point becomes 0, so that the voltages on the sending side and the load point match. Using this fact, in the present invention, the load point voltage can be estimated using the sending-side voltage at the time of zero crossing.

  So far, the sequential calculation method of the measurement signal of the sensor switch has been described mainly based on the concept of the determination unit 104 of FIG.

  Next, as calculation contents of the calculation means 102 in FIG. 2, for example, an impedance (R, X) estimation method and a parameter estimation method will be described.

  Formula (3) described above is a calculation formula obtained by solving the power drop formula from the delivery to the load for R and X. Here, it is assumed that a sensor-equipped switch is installed on the delivery side and measurement signals (voltage V, current I, phase) can be collected. At this time, the unknown variables in the equation (3) are R and X of the line impedance, the voltage Er at the load point, and the phase difference angle.

  In this case, since there are three unknowns in the equation (3), which is a formula for calculating the line impedance R or X, it can be solved by making three simultaneous. The present invention is characterized in that, by paying attention to the fact that the load amount or power generation amount of the power system changes with the passage of time, a simultaneous equation is created using measurement signals at least at three times, and a solution is obtained.

  The above relationship will be described with reference to the drawings. FIG. 8 is a diagram showing line impedance characteristics.

  The equation for calculating the line impedances R and X shown in equation (3) has the load point voltage Er and phase difference angle as unknowns on the right side. Other variables can be treated as known by substituting measurement signals. Here, if the equation (3) into which a measurement signal at one time is substituted is plotted with the resistance R, the reactance X, and the voltage Er as three-dimensional coordinate axes and the phase difference angle as a parameter, the line impedance characteristic of FIG. 8 can be obtained. .

  Although there are three solutions (R, X, Er) on the cone showing the line impedance characteristic of FIG. 8, it cannot be specified as it is. If a two-time cone is drawn, it intersects at the intersection line, but three solutions (R, X, Er) cannot be specified. On the other hand, the three cones created at three times have intersections and three solutions (R, X, Er) are obtained.

  FIG. 9a is a diagram showing three cones of line impedance characteristics made at three times, and FIG. 9b is a diagram showing a two-dimensional section by impedance for the three cones made at three times. In FIG. 9a, for example, the condition of the voltage Er is set for the three cones of the line impedance characteristic created at three times in FIG. 9a, and according to FIG. Therefore, the line impedances R and X at this time can be estimated as the characteristics of the line in FIG. Thus, here, the measurement signal at 3 times is substituted into the equation (3), and the cone is plotted to estimate the characteristics of the line. The present invention is characterized in that a solution is obtained by using a measurement signal at a plurality of times to provide simultaneous power drop equations.

  By the way, when power flow inversion occurs in the power system (for example, when the current becomes 0), the above equation (3) for calculating the resistance R and the reactance X has a large denominator, so an appropriate solution cannot be obtained or cannot be calculated. become. Tidal current reversal (reverse power flow) is a phenomenon that has not been considered in situations where there is little introduction of renewable energy. The present invention is characterized by comprising determination means 104 for determining whether a solution cannot be obtained or calculation is not possible, which occurs due to a recent increase in renewable energy.

  The present invention is characterized by switching a calculation procedure such as interpolating a calculation result using a prior calculation result or a previous and subsequent calculation result when a determination result that cannot be calculated by a power flow inversion is obtained in the determination means 104. To do. If the calculation is not possible, the output data will be lost. However, supplementing the data will prevent the data from being lost, and the subsequent signal processing will not be affected by the calculation impossibility of the previous processing.

  Further, the present invention uses the determination result in the determination unit 104 to display on the screen that the tidal current has occurred and notify the operator, and also displays the accuracy level of the impedance (R, X) estimation result for operation. This is used to notify a user or leave a log. For the operator, it is possible to determine the reliability of the result that cannot be understood from only the calculation result from the output result. Here, the effect of supporting the operator's judgment can be obtained by graphically drawing the phenomenon that occurs in the power system on the display screen as shown in FIGS. 8, 9a, and 9b.

  By the way, when substituting measurement signals at a plurality of times into the equation (3), which is a formula for calculating the resistance R and reactance X, when there is a change in system state or when noise is mixed, an analytical solution is obtained. It becomes difficult. FIG. 10a schematically shows a case where an intersection point is obtained on a two-dimensional cross section by impedance for the three cones shown in FIG. 9b, and FIG. 10b schematically shows a case where an intersection point cannot be obtained. . As shown here, if the above-described cone is described with reference to the top view, when there is the above-described influence, there are cases where the three cones intersect at one point and when the three cones intersect at one point. Generally, when an error is included like a measurement signal, the least square method is used as a method for obtaining a plausible solution. In addition, optimization calculation using some kind of evaluation method, statistical method considering probability distribution, numerical calculation method for obtaining a convergence solution, regression analysis, and the like can be used. The present invention can utilize these solutions.

  Here is an example of a simultaneous solution. First, in the case of FIG. 10a in which the plurality of cones have one intersection point, an appropriate solution method such as an analytical solution or a numerical calculation is used as a solution method of the simultaneous equations.

  On the other hand, in the case of FIG. 10b that does not have one intersection, since an analytical solution cannot be used, a solution by numerical calculation or the like is used. First, according to the procedure described above, a plurality of calculation formulas are prepared by substituting measurement signals collected at a plurality of times into formula (3). At this time, simultaneous measurement may be performed using more measurement signals than three times.

  If it sees graphically, the position where the distance with the several cone surface produced with the measurement signal of several time will approach most is searched.

  In order to express explicitly the error when the measurement signal is substituted into the equation (3), the errors Dr and Dx are put out on the left side to create the equation (5). The measurement signals are P, Q, I, and Es on the sending side assuming a sensor switch. This may be Es, I, power factor, or Es, I, phase angle of voltage / current, and can be converted as appropriate.

  The unknowns are the line impedances R and X, and the load point voltage Er. Here, the problem is that R, X, and Er with the smallest total error are calculated as solutions. Formula (5) is a formula for calculating a difference (error) between the solutions R, X, and Er common to the simultaneous equations at a plurality of times and the formula into which the measurement signal at each time is substituted.

  Next, according to the equation (6), in order to make the error a positive value, the sum of each time is taken after being squared (or absolute value). Here, the error of the voltage Er is indicated by DEr, and the symbol Σ indicates the addition of errors for a plurality of times.

  What is necessary is just to obtain | require R, X, and Er where this error Dsum becomes the smallest. Here, if a constraint condition is created by using the above-described graphical interpretation for possible regions of R, X, and Er, the solution is a triangle around the center of the three cones, and from the sending side voltage Es. It may be in the upper and lower limit range of the voltage fluctuation.

  If the above is arranged, it becomes a problem to search for R, X, and Er with the smallest total error (square or absolute value) under the above-mentioned constraint conditions. Specifically, a numerical calculation method for obtaining R, X, and Er can be appropriately selected. The present invention does not limit these solutions.

  For example, PSO (Particle Swarm Optimization, particle swarm optimization calculation) known as one of heuristic methods can be used. The PSO initializes a plurality of solution candidates as particles, and searches for a solution by repeating a procedure of moving the solution candidates (particles) toward the particle position having the smallest error among them. In the above example, solution candidates (particles) are initially set in the R, X or R, X, Er space to search for solutions.

  Alternatively, there is a method of finding a solution by paying attention to a region where a solution is likely to exist and linearly approximating that region. Whereas the prior art linearly approximates the voltage drop equation itself, linearly approximating only the peripheral region of the solution maintains the overall characteristics of the solution space. This is equivalent to the Newton-Raphson method being a method of performing convergence calculation by linearly approximating the solution peripheral region of the nonlinear equation rather than a method of linearly approximating the target nonlinear equation. In other words, the solution can be obtained by appropriate numerical calculation such as Newton-Raphson method.

  By the way, in order to follow the state change of the electric power system, it is desirable to shorten the interval of simultaneous time. On the other hand, the larger the state change, the more convenient the search for the solution. The specific time setting is determined in consideration of the accuracy of the measurement signal of the measuring device, the sampling period, and the like.

  The relationship between the above solution and the period also depends on the calculation load of the solution. In general, a calculation load for finding a solution of a nonlinear equation is heavy, and this may be called a defect. However, recent processor processing capacity is high, and if necessary, a cloud computer or the like can be used via communication means. Therefore, it is only necessary to estimate a calculation load necessary for achieving the original purpose and select a calculation means corresponding to the calculation load.

  The second embodiment shows a configuration example in which an interpolation function is added to the power system characteristic estimation apparatus of FIG. 2 described in the first embodiment.

  In the second embodiment illustrated in FIG. 11, an interpolation unit 105 and a switching unit 106 are added to the power system characteristic estimation apparatus in FIG. 2. According to the configuration of the first embodiment, since the output of the solution is canceled when the current reversal occurs when the measurement signal such as the current crosses zero, the output of the solution is stopped while the measurement signal is input.

  As a method for preventing this, in the second embodiment of the present invention, as shown in FIG. 11, an interpolation unit 105 is provided that generates data by interpolating or extrapolating the surrounding estimation result at the time of tidal current inversion. A switching unit 106 that switches between the output unit 103 and the interpolation unit 105 is provided using the determination result of the calculation possibility determination unit 104. In this way, when there is a tidal current inversion, the estimated value is output by interpolation or extrapolation to prevent data loss.

  The power system characteristic estimation apparatus shown in FIG. 11 is basically “means 101 for inputting a signal related to the power system, and an unknown number included in the calculation formula by substituting the input signal of the input means 101 into a calculation formula related to the power system. Calculation means 102 for calculating as a solution, interpolation means 105 for interpolating or extrapolating the output of the calculation means 102, means 104 for determining the presence of the solution of the calculation formula from the input signal of the input means 101, and the determination means 104 A power system comprising: means 106 for switching the outputs of the calculation means 102 and the interpolation means 105 using the determination result; and means 103 for outputting the switching result of the switching means 106 and the determination result of the determination means 104. Characteristic estimation method and apparatus ".

  FIG. 12 is a flowchart showing the processing procedure of the present invention. Follow the phenomenon that occurs in the power system by repeating the calculation procedure along the time transition. This repetition period may be synchronized with the input period of the measurement signal. Since the cycle varies depending on the measurement device, the cycle is determined based on the device configuration. Or you may calculate repeatedly based on time settings, such as 10 minutes, 30 minutes, and 1 hour.

  The flowchart in FIG. 12 sequentially executes the processes from the process step S12 to the process step S19, and these processes are repeatedly executed by the process step S11 and the process step S20.

  According to this flowchart, a measurement signal is input in processing step S11, tidal current reversal is detected in processing step S12, and whether or not calculation is possible is determined in processing step S13. The process proceeds to the process on the S15 side, and when the calculation is impossible, the process proceeds to the process on the step S18 side. In the process at the step S18 when calculation is impossible, calculation values are interpolated and extrapolated.

  As a result of the determination, when it is possible to calculate, a plurality of time measurement signals of at least three times are prepared in processing step S15, a voltage drop type simultaneous signal is provided in processing step S16, and line impedance, voltage drop, phase is processed in processing step S17. The corner is calculated and the result is output in processing step S19.

  In the third embodiment, a specific application example of the above-described power system characteristic estimation device will be described. This example is an application example to a voltage drop estimation or voltage optimization function, and is a power system management device configured to be applied to a so-called line voltage adjustment device.

  In the above-described procedure for estimating the line impedance, the intersection of the cones is assumed to be a solution as a graphic explanation. If the space where this intersection is present can be represented by three-dimensional coordinates of R, X, V (impedance is R, X, and voltage is V), then the voltage Er at the load point is obtained simultaneously. The voltage Er at the load point is obtained without substituting the set value (line impedance) into the voltage drop equation shown in the equation (1).

  LRT, SVR, and the like that have been conventionally used as line voltage adjusting devices perform voltage conversion by setting the primary and secondary winding ratios by tap switching. One of the tap setting methods is a method called LDC (Line Drop Compensator), which is incorporated in the line voltage adjusting device such as the LRT or SVR. This is a method of estimating the voltage drop from the local measurement signal to the load point and controlling the tap so that the voltage at the load point becomes an appropriate value. The parameter used to estimate this voltage drop is called the settling value and is set in the device in advance.

  Here, in the LDC method, as shown in FIG. 13, the voltage drop is estimated by multiplying the line impedance Z (= R + jX) up to the load point by the current I flowing through the terminal. In this case, the line impedance Z (= R + jX) is set in the LDC as one of parameters set in advance called a set value. This requires a procedure for calculating the line impedance to the load point based on the measurement signal. Since the line impedance to the load point differs depending on the line, it is necessary to collect measurement signals for each line.

  As described above, in order to adjust the voltage by LDC tap switching, the settling value (line impedance to the load point) must be calculated through many procedures. However, as described above, the load point fluctuates due to load fluctuations, renewable energy power generation, and the like, so the settling value calculated in advance may not necessarily reflect the line characteristics correctly. This problem is manifested by the expansion of the introduction of renewable energy, and causes an error in the voltage adjustment results.

  The power system characteristic estimation apparatus 100 of the present invention includes means 102 for estimating the voltage drop to the load point using the measurement signal sequentially input as described above. Therefore, as compared with the procedure for estimating the voltage drop by multiplying the current based on the set value (line impedance) set in advance as in the above procedure, the line impedance to the load point while following the state of the power system. The voltage drop can be estimated. Therefore, according to the present invention, a procedure for collecting measurement signals in advance for each line becomes unnecessary. Since the voltage drop from the sending side to the load point and the line impedance can be estimated sequentially, it is possible to follow the load point change due to load fluctuation and renewable energy power generation. The present invention uses the output signal of the present invention as a set value, a control parameter, or a control signal for instructing the operation of the voltage regulator described above.

  The present invention constructs a power system management apparatus that is a power system control system using the above features. For example, as shown in FIG. 14, for the purpose of optimizing the voltage of the line, a voltage adjusting device (here, SVR), the characteristic estimating device 100 of the present invention, and a measuring device 120 are installed. Then, by adjusting the delivery voltage from Es to Es ', the voltage at the load point is increased from Er to Er', and the voltage drop at the load point is suppressed. In order to calculate this voltage drop, the line impedance or the like is calculated and set as a set value of the voltage regulator. Here, the characteristic estimation apparatus 100 of the present invention may be incorporated in the voltage adjustment apparatus, or may be executed as computer software via some communication path. In the above description, the settling value is calculated, but a specific control signal (a tap value in the case of SVR) may be calculated instead of the settling value. Further, by recording the output signal of the characteristic estimation device 100 and the determination signal in the above procedure in the recording device 110, it can be used for post-mortem analysis.

  By shortening the time period from collection of the measurement signal to transmission of the control signal, control corresponding to the phenomenon occurring can be performed, and so-called real-time control or online control can be realized. By the way, the voltage regulator has different response characteristics depending on its operating principle. Since LRT, SVR, etc. mechanically switch the winding ratio between the primary side and the secondary side, switching time in seconds is required. On the other hand, a voltage regulator using a semiconductor element such as SVC (Static Var Compensator) has a faster response speed. Therefore, the present invention adjusts the frequency characteristics such as the calculated settling value or control signal so as to adapt to these device characteristics. For this reason, a filter process or device for adjusting the frequency characteristics is used. The principle of frequency adjustment by a filter is known, and the mounting method is not limited.

  The present invention is characterized by having means for estimating the voltage at the load point by creating simultaneous equations using measurement signals at a plurality of times, wherein the plurality of times are at least three times, and the power flow inversion described above Set except for the time when it is determined that the calculation is not possible due to the occurrence of (reverse power flow).

  In the fourth embodiment, application to accident point estimation will be described as a specific application example of the power system characteristic estimation device. Specifically, the power system management device applied to the protective relay device that measures and calculates the distance (line impedance) to the fault point in the power system and determines the opening operation of the circuit breaker is configured.

  The above-described embodiment uses a voltage drop equation from the sending side to the load point. Here, the load point is not a location where the actual load device or the power generation device is linked, but a location where there is a virtual load combining the load device and the power generation device.

  By the way, when an accident occurs in the power system, a large load change occurs in the power system. There are many types of accidents, but in the case of a ground fault, power flows through the ground fault resistance. If the line is cut, the load ahead is released and the power flow is reduced. Changes in the system state due to these accidents can be collected as time-series measurement signals by the above-described measurement equipment. The accident can be treated as a change in system configuration and is observed as a change in load and load point before and after the accident.

  The present invention estimates the line impedance, that is, the distance to the load point by utilizing the fact that the load point changes before and after the accident as shown in FIG. By calculating R and X from the sending side to the load point, and using the impedance per distance (R, X) based on the line type of the corresponding line, the estimated line impedance is converted into a distance so that it can be regarded as a load point. Calculate the distance to the accident point.

  On the other hand, an accident can be seen as a mixture of transient and steady changes, unlike a steady phenomenon. The above equation (3), which is a formula for calculating R and X, may be solved as a transient response. The transient response is observed as a vibration phenomenon caused by RLC (resistance, inductance, capacitor) and generally has a high frequency component. Therefore, the measurement signal is decomposed by the frequency component, and the stationary property is extracted by using the low frequency component. This frequency decomposition may be replaced with, for example, wavelet decomposition. In this way, the measurement signal is used after being subjected to some conversion or filtering, thereby removing a component that becomes noise in the application of the present invention. And estimation accuracy is improved by estimating the above-mentioned line impedance.

  In addition, as a relay type of the protective relay device to which the present invention can be specifically applied, a reactance relay is typically considered, and it is determined that the measured reactance value is equal to or less than a predetermined value as an accident in the protection area. To do. In addition, the present invention can be applied to a distance relay including an element for measuring a distance, or a step-out detection relay configured by a combination of distance relays.

  The protective relay device is installed in the electric power system, measures the line impedance on the load point side, and provides the protective output of the electric power system according to the set value of the given line impedance, the protective relay device The output of the power system characteristic estimation device is used as the line impedance to be measured.

  Since it is indispensable to find the accident point to start the accident recovery of the power system, estimating the accident point using the present invention starts the accident recovery promptly and shortens the power failure time. It is effective.

  In addition, the present invention combines the likelihood of an accident in the power system, the surroundings in advance, the waveform of the measurement signal, the line impedance to the load point, etc., thereby detecting the accident, estimating the cause of the accident, and locating the accident point. It can be performed.

  As Example 5, classification by clustering will be described.

  Consider a case in which photovoltaic power generation is linked to a power system, and as shown in FIG. 3, a reverse power flow due to power generation occurs during the day and a forward power flow due to consumption occurs at night. If the line impedance up to the load point calculated using the measurement signal on the sending side is plotted on the RX plane, the distribution of load points for power generation and consumption can be made. By combining the time history, the distribution of load points for power generation and consumption by time can be obtained. Further, if the voltages at the load points are combined, a load point distribution in the RXV space can be obtained as shown in FIG.

  These distributions are distribution data indicating characteristics of load and power generation, and can be analyzed by using many methods called grouping, clustering, separation of mixed distribution, and the like. For example, three groups classified in the figure show characteristic examples at daytime, nighttime, and accidents. In the present invention, the system state is determined based on which of the groups the system characteristic calculated from the measurement signal belongs to.

  By finding such a characteristic peculiar to the power system, it can be used for power supply planning, facility planning, voltage optimization control, and the like. Although not shown here, group classification and time transition may be combined. When a transition is set as a steady operation between groups that are repeated on a daily basis, a time when a transition deviating greatly is detected as an abnormal operation.

  By detecting that the measurement signal has a difference with respect to these steady distributions, it can be determined in association with, for example, a change in system configuration, the occurrence of an accident, or the like.

  If an accident occurs on a track, if the point of failure is regarded as a load point, the track impedance will deviate greatly from the steady distribution position. By determining such a difference in distribution between the normal time and the abnormal time, it can be used for accident detection and further estimation of the cause of the accident.

  As Example 6, some further modifications and alternative examples of the apparatus of the present invention will be described.

  First, the calculation means 102 stores the relationship between the input signal and the output signal related to the voltage drop equation calculated in advance as tabular data, searches the table with the input means of the input signal, and outputs the search result to the output means. Can be output from. As a result, a transient calculation load can be reduced.

  The output means 103 preferably includes a display screen capable of drawing at least characters or a storage device capable of storing at least text data. On the display screen, it is preferable to draw the position where the solution exists on a space having the line impedance from the power supply side to the load point and the load point voltage as coordinate axes.

  When the determination unit determines that there is no solution, the calculation unit may calculate the voltage at the load point on the assumption that the power flow is reversed in the power system and the voltage drop from the sending side to the load point is zero.

100: characteristic estimation device 101: input means 102: calculation means 103: output means 104: determination means 105: interpolation means 106: switching means 110: recording device 120: measuring instrument

Claims (21)

Input means for inputting signals related to the power system,
A calculation means for substituting an input signal of the input means for a calculation formula related to a power system and calculating an unknown contained in the calculation formula as a solution;
Determination means for determining the presence of a solution of the calculation formula from an input signal of the input means;
An electric power system characteristic estimation apparatus comprising output means for outputting a solution calculated by the calculation means and a determination result of the determination means. Input means for inputting signals related to the power system,
A calculation means for substituting an input signal of the input means for a calculation formula related to a power system and calculating an unknown contained in the calculation formula as a solution;
Interpolation means for interpolating or extrapolating the output of the calculation means;
Determination means for determining the presence of a solution of the calculation formula from an input signal of the input means;
Switching means for switching the output of the calculation means and the interpolation means using the determination result of the determination means;
An electric power system characteristic estimation apparatus comprising output means for outputting a switching result of the switching means and a determination result of the determination means. A power system characteristic estimation device according to claim 1 or 2, wherein
The calculation means is a power system characteristic estimation apparatus characterized in that a solution is calculated by using simultaneous calculation formulas related to the power system using an input signal at least at three times. A power system characteristic estimation device according to any one of claims 1 to 3,
The power system characteristic estimation apparatus characterized in that the determination means determines from the input signal that the magnitude of the power flow on the sending side is zero or near zero. The power system characteristic estimation device according to any one of claims 1 to 4,
The input means for the input signal inputs the voltage, current and phase on the sending side of the power system, and the calculating means is a voltage drop equation from the sending side to the load point, and the voltage, current and phase on the sending side at least 3 times A power system characteristic estimation device that calculates the voltage drop and / or the line impedance from the sending side to the load point as a solution by substituting and simultaneous. A power system characteristic estimation device according to any one of claims 1 to 5,
The power system characteristic estimation apparatus characterized in that the calculation means uses a measurement signal at least three times excluding the time when the determination means determines that there is no solution, and uses a voltage drop equation simultaneously. A power system characteristic estimation device according to any one of claims 1 to 6,
A power system characteristic estimation apparatus characterized in that the calculation means calculates a solution by using as an index that the error is minimized by using a measurement signal at least at three times to provide simultaneous voltage drop equations. A power system characteristic estimation device according to any one of claims 1 to 7,
The calculation means calculates a voltage drop from the power system sending side to the load point,
The power system characteristic estimation device according to claim 1, wherein the output means outputs a control amount or control parameter of a voltage regulator for correcting the voltage drop. A power system characteristic estimation device according to any one of claims 1 to 8,
The calculation means calculates the line impedance from the sending side to the load point by solving the voltage drop equation by regarding the fault point occurring in the power system as a load point, and calculating the line impedance from the sending side to the load point. A power system characteristic estimation device according to any one of claims 1 to 9,
The calculating means is means for storing the relationship between the input signal and the output signal related to the voltage drop equation calculated in advance as tabular data, searching the table with the input means of the input signal, and outputting the search result as the output means. The characteristic estimation apparatus of the electric power system characterized by outputting by. The power system characteristic estimation device according to any one of claims 1 to 10,
The power system characteristic estimation device, wherein the output means is a display screen capable of drawing at least characters or a storage device capable of storing at least text data. A power system characteristic estimation device according to any one of claims 1 to 11,
The power system characteristic estimation apparatus characterized in that the output means draws a position where a solution exists in a space having a line impedance and a load point voltage from a power supply side to a load point as coordinate axes. A power system characteristic estimation device according to any one of claims 1 to 12,
When the determination means determines that there is no solution, the calculation means calculates the voltage at the load point on the assumption that the power flow is reversed in the power system and the voltage drop from the sending side to the load point is zero. A power system characteristic estimation device. Input means for inputting signals related to the power system,
A calculation means for substituting the input signal of the input means into a calculation formula related to a power system and calculating an unknown contained in the calculation formula as a solution;
Determination means for determining the presence of a solution of the calculation formula from an input signal of the input means;
Output means for outputting the solution calculated by the calculation means and the determination result of the determination means;
Storage means for storing the solution calculated by the calculation means;
A power system characteristic estimation device comprising statistical processing means for statistically processing the solution of the storage means. The statistical processing means of the solution according to claim 14 is:
An apparatus for estimating characteristics of a power system, wherein current measurement signals are grouped based on a grouping result of past solutions. Input signals related to the power system,
Substituting the input signal input into the calculation formula related to the power system, and calculating the unknown contained in the calculation formula as a solution,
Determining the presence of a solution of the formula from the input signal;
A power system characteristic estimation method, wherein the calculated solution and the result of the determination are output. Input signals related to the power system,
Substituting the input signal input into the calculation formula related to the power system, and calculating the unknown contained in the calculation formula as a solution,
Determining the presence of a solution of the formula from the input signal;
Interpolate or extrapolate the solution to obtain the interpolated value,
Using the determination result, the solution and the interpolated value are switched,
A method for estimating characteristics of a power system, wherein a switching result, the solution, and the result of the determination are output. A power system characteristic estimation device that estimates the state of a load point of a power system from the amount of electricity of the power system obtained at a measurement point of the power system,
Input means for inputting the amount of electricity in the power system together with time information;
A calculation means for substituting the amount of electricity into a calculation formula related to a power system and calculating an unknown contained in the calculation formula as a solution;
Judgment means for judging the existence of a solution of the calculation formula from the amount of electricity of the electric power system relating to power flow,
An electric power system characteristic estimation apparatus comprising output means for outputting a solution calculated by the calculation means and a determination result of the determination means. A power system characteristic estimation device that estimates the state of a load point of a power system from the amount of electricity of the power system obtained at a measurement point of the power system,
Input means for inputting the amount of electricity in the power system together with time information;
A calculation means for substituting the amount of electricity into a calculation formula related to a power system and calculating an unknown contained in the calculation formula as a solution;
Interpolation means for interpolating or extrapolating the output of the calculation means;
Judgment means for judging the existence of a solution of the calculation formula from the amount of electricity of the electric power system relating to power flow,
Switching means for switching the output of the calculation means and the interpolation means using the determination result of the determination means;
An electric power system characteristic estimation apparatus comprising output means for outputting a switching result of the switching means and a determination result of the determination means. A power system management device including a voltage adjustment device that is installed in the power system and adjusts the voltage on the load point side,
The voltage adjusting device controls a voltage drop between the installation point and the load point side according to a given line impedance settling value, and the line impedance settling value is set according to claims 1 to 8. An electric power system management apparatus provided from output means of the power system characteristic estimation apparatus according to any one of the preceding claims. A power system management device including a protective relay device that is installed in the power system and measures a line impedance on the load point side to give a protection output of the power system,
The power system management device, wherein the output of the power system characteristic estimation device according to any one of claims 1 to 8 is used as the line impedance measured by the protective relay device. .

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