JP2021050954A - Power grid monitoring device and method - Google Patents

Abstract

To provide a power grid monitoring device and method with which it is possible to obtain effects by a simple device structure that make highly accurate locating possible.SOLUTION: Provided is a power grid monitoring device for locating a fault point using surges in a power grid, comprising: first means for measuring a surge waveform propagating through the power grid and obtaining a measured waveform; second means for artificially generating a surge waveform that propagates through the power grid, on the basis of grid composition information of the power grid and fault point information; third means for determining similarity between the measured waveform and the simulated waveform and locating a fault point; and fourth means for outputting the orientation result of the located fault point.SELECTED DRAWING: Figure 2

Description

The present invention relates to a power system monitoring device and method for determining an accident point in a power system.

The power system is a large-scale system that is constructed and operated by combining many devices and control methods for the stable supply of electric power. It is known that the state of the electric power system changes due to various factors, and the notation is made by physical quantities such as voltage, current, electric power, and frequency. The phylogenetic state has an area spread created by the phylogenetic configuration and is accompanied by temporal changes. In addition, it changes greatly depending on the power generation and load connected to the grid. Since the energy supply should be stable, various control devices and methods are used to maintain a steady state.

When an accident that interferes with power supply occurs, it is an indispensable request to promptly identify the accident point (where the accident occurred) and start restoration work in order to improve supply reliability. .. And in order to realize prompt accident recovery, it is necessary to promptly grasp the details of the accident. However, at present, in many cases, the accident point is identified by human confirmation work at the site where the accident occurred. Therefore, it takes time for the person in charge to work in addition to the time required to arrive at the site before the accident point is identified, and personal situations such as experience, knowledge, and physical condition are included in this time.

On the other hand, in recent years, with the progress of networks and digital signal processing, signals measured by sensors installed in electric power systems have become available. Many techniques for estimating the system state using sensor measurement signals have been proposed. The technique for estimating the accident point is called accident point locating, and an accident point locating method such as a surge method or a frequency method has been proposed.

Among these, the surge method defines the accident point using the arrival time of the surge propagating on the track. It is known that surges are classified as traveling waves, propagate at a speed close to that of light, and are reflected at points where impedance mismatches occur. There is an accident point locating method for locating an accident point using digital data of a measurement waveform obtained by sampling the waveform of this surge with an AD converter.

Patent Document 1 provides a method capable of accurately determining an accident point even when a surge generated at the time of an accident is attenuated due to line propagation.

Japanese Unexamined Patent Publication No. 2012-108011

The technique described in Patent Document 1 is based on measuring the arrival time of a surge generated and propagating at an accident point of an electric power system at a plurality of points on a line and calculating the arrival time difference. Then, the principle is to calculate the accident point by creating a relational expression using the distance from the accident point to the measurement point, the arrival time difference of the surge, and the propagation speed of the surge. However, there are the following problems to put it into practical use.

The waveform of the measurement signal of the power system may be distorted due to noise, harmonics, crosstalk between lines, etc., and it may be difficult to accurately detect the arrival time of the surge.

In order to measure the surge arrival time difference at multiple locations, it is necessary to synchronize the time of the measuring device at each location. However, for example, the time accuracy of GPS (Global Positioning System) is often about microseconds, which increases the cost of the device for improving the time accuracy.

In order to calculate the accident point using the arrival time difference, the surge propagation speed is required, but it is known that the surge propagation speed changes depending on the conditions such as the line type. If the propagation speed measured in a preliminary experiment or the like is used, an error may occur in the measurement result due to a change in the propagation speed. Alternatively, if a means for measuring the surge propagation speed of the line of the target system is used, the equipment cost will increase.

It is known that a surge propagating in a line is reflected at a point where impedance mismatch occurs and travels in the opposite direction. Since the reflection point is a device such as a branch point of a railroad track or an insulator, the reflected wave cannot be avoided. Therefore, the measurement waveform includes a direct wave that propagates directly from the accident point and a reflected wave that is reflected and propagated at the reflection point. When detecting the arrival time of the waveform, the reflected wave becomes noise and may reduce the detection accuracy.

From the above, it is an object of the present invention to obtain a power system monitoring device and method capable of obtaining an effect of enabling highly accurate positioning with a simple device configuration.

From the above, the present invention is a power system monitoring device for defining an accident point using a surge in the power system, and is a first means for measuring a surge waveform propagating in the power system to obtain a measured waveform, power. The second means of simulating the surge waveform propagating in the power system based on the system configuration information and the accident point information of the system to obtain the simulated waveform, determining the similarity between the measured waveform and the simulated waveform and determining the accident point. It is characterized by comprising a third means, a fourth means for outputting the marking result of the marked accident point.

Further, the present invention is a power system monitoring method for determining an accident point by using a surge in the power system. The surge waveform propagating in the power system is measured to obtain a measurement waveform, and the system configuration information and the accident point of the power system are obtained. Based on the information, the surge waveform propagating in the power system is simulated and generated, the simulated waveform is obtained, the similarity between the measured waveform and the simulated waveform is judged, the accident point is defined, and the localization result of the defined accident point is output. It is a feature.

According to the present invention, it is possible to obtain the effect of enabling highly accurate localization with a simple device configuration.

Specifically, it is not necessary to measure the arrival time of the surge waveform, no means for removing the reflected wave as noise is required, and no means for setting or measuring the propagation speed of the surge is required. All of these contribute to the simplification of the device configuration and the improvement of the positioning accuracy.

The figure which shows the phenomenon of surge propagation when a surge occurs at an accident point. The figure which shows the phenomenon of surge propagation when a surge occurs at an injection point. The figure which shows the processing procedure of the accident point setting of this invention. The figure which shows the example of the simulated waveform generation by drawing. The figure which shows the example of the simulated waveform generation by drawing. The figure which shows the example of the simulated waveform generation by drawing. The figure which shows the example of the simulated waveform generation by drawing. The figure which shows the example of the simulated waveform generation by drawing. The figure which shows the notation example of the single-shot waveform arranged at the surge arrival time in the drawing procedure. The figure explaining the calculation method of the similarity of the measured waveform and the simulated waveform. The figure explaining the similarity between the measured waveform and the simulated waveform. The figure which shows the relation example of the similarity with the accident point when focusing only on the accident point. The figure explaining the processing procedure of the accident point setting. The figure explaining the device configuration example of the accident point setting. The figure explaining the configuration example of the display screen of the accident point setting.

Hereinafter, examples of the present invention will be described with reference to the drawings and the like. The following examples show specific examples of the contents of the present invention, and the present invention is not limited to these examples, and is by those skilled in the art within the scope of the technical idea disclosed in the present specification. Various changes and modifications are possible.

Power system technology may be described separately for distribution and transmission systems. The following will focus on the distribution system, but it is a technology that can also be applied to the power transmission system.

In the description of the present invention, AC voltage and current may be simply referred to as voltage and current.

The present invention is characterized in that an accident point is defined by signal-processing the measurement waveform of a surge collected by using a measuring means.

The phenomenon of surge propagation in the power system will be described with reference to FIGS. 1a and 1b. Here, FIG. 1a shows a case where a surge occurs at an accident point, and FIG. 1b shows a case where a surge occurs at an injection point.

The horizontal axis of these figures indicates the line of the power system, and the accident point Pf (or injection point Pi), the reflection point Pr, and the measurement point Ps are arranged. The vertical axis shows the passage of time t after the accident occurred. Since the surge propagates along the track with the passage of time, the relationship between position and time is drawn as a diagonal line in the figure. In the following description, this diagonal line will be referred to as a propagation line.

The cause of the surge is a surge (FIG. 1a) that occurs and propagates at the accident point Pf as a transient electrical phenomenon when an accident occurs. In addition, there is a surge (FIG. 1b) generated by injecting a pulse into the line using some kind of pulse generating means. In the latter case, a surge can be artificially generated at a position different from the accident point Pf (injection point Pi) at a timing different from the accident occurrence.

The surge generated in this way can be collected as a surge waveform by measuring a voltage or current waveform at a measurement point Ps prepared on the line. This measurement waveform is composed of a direct wave Wd that directly reaches the measurement point Ps from the accident point Pf (or injection point Pi) and a reflected wave Wr that reaches the measurement point Ps after being reflected at the reflection point Pr. The reflection point Pr is a point where the surge is reflected due to electrical impedance mismatch, etc., and there are equipment such as line branch points, insulators, line ends, etc., and voltage adjustment equipment, which can be grasped in advance from the system configuration information. It is possible. The accident point Pf itself also becomes the reflection point Pr. The surge can occur in either the positive or negative polar direction. Further, the amplitude of the reflected wave Wr may be inverted (positive or negative is inverted) before and after the reflection. If the amplitude inversion due to reflection (positive / negative is inverted) can be correctly estimated, signal processing can be performed focusing on the magnitude, polarity (positive / negative), and position of the surge waveform. However, with regard to these polarities, the magnitude and position of the surge waveform can be focused on regardless of the presence or absence of inversion by taking the absolute value or the square value of the waveform amplitude.

In this way, the surge measurement waveform is related by the positional relationship between the accident point Pf (or injection point Pi) and the reflection point Pr, the surge propagation speed, and the accident occurrence time.

To summarize the above, the position of the accident point Pf (or injection point Pi) and the surge waveform are related by the following known variables and unknown variables. First, the known variables are the positions of the reflection point Pr and the measurement point Ps on the power system. On the other hand, the unknown variables are the position of the accident point Pf (or injection point Pi), the accident occurrence time, and the surge propagation speed.

These variables can be expressed differently depending on the phenomenon of interest. For example, the accident occurrence time is the arrival time of the surge when focusing on the measured waveform. The surge propagation speed can be converted into the time width of the waveform by focusing on the measured waveform. In the following description, these terms may be replaced as appropriate.

In the present invention, the above variables are used to determine the accident point by the processing procedure shown in FIG. 2 below.

In the accident point determination process, first, in the process step S1, the system configuration information is input. The positions of the reflection point Pr and the measurement point Ps can be determined based on the system configuration information. In addition, a simulated waveform generation means is prepared. In this preparatory stage, a simulated waveform generation means for generating the direct wave Wd and the reflected wave Wr of the surge is prepared with the accident point Pf (or injection point Pi), the accident occurrence time, and the surge propagation speed as variables. Also, set the initial value of the variable. The series of processes up to this point can be said to be the preparatory stage.

In the process step S2, the process waits until the occurrence of an accident is actually detected. When an accident occurs, a surge waveform is input in processing step S3. Here, as the surge measurement waveform Ws, a waveform in which the surge direct wave Wd and the reflected wave Wr are superimposed is input.

In the process step S4, a search for determining the accident point Pf is executed. Specifically, in the processing steps S41, S42, and S43, the accident point is temporarily set by using the simulated waveform generating means prepared in advance in the processing step S1, the delay time and the waveform width are set as variables, and the simulated waveform Wp. To generate. A plurality of sets of simulated waveforms Wp are generated by making these variables variable. In the processing step S44, the similarity between the measured waveform Ws and the simulated waveform Wp is calculated. In the process step S45, the relationship between the accident point and the similarity is stored.

In the process step S5, if the end condition is determined and satisfied, the search procedure ends. If it is not satisfied, the procedure of the above processing steps S41, S42 and S43 is repeated as appropriate.

The search procedure of the present invention is to search for a solution (variable having the highest similarity) by using a numerical analysis method. For this purpose, search methods such as full search and optimization calculation are used. As the end condition of the repetition, for example, the number of repetitions, the convergence of similarity, and the like are used.

Finally, in the processing step S6, when the end condition is satisfied, the accident point Pf in which the measured waveform Ws and the simulated waveform Wp are most similar is selected as the localization result and output in the processing step S7. The localization result is output using characters, figures, images, voices, etc. so as to be appropriately transmitted to the person in charge of the accident point Pf removal work. In addition, the progress is accumulated as log data.

As is clear from the above description, the present invention evaluates the similarity between the measured waveform Ws and the simulated waveform Wp using an index called similarity. As will be described later, the similarity is calculated as a numerical value representing the similarity of the waveform regardless of the position (time) and the waveform width (time width) of the waveform. Therefore, if appropriate conditions are added, it can be paraphrased into technical terms such as waveform correlation calculation and waveform pattern matching.

One of the features of the present invention is to create a simulated waveform Wp by combining the direct wave Wd of the surge and the reflected wave Wr. There are two methods for creating the simulated waveform Wp: a drawing method and a mathematical method. Both are compatible methods that represent the same surge propagation.

In the following description of the embodiment, first, the method by drawing will be described in principle with reference to FIGS. 3a to 3e, and then the method by mathematical formula will be described.

The simulated waveform generation by drawing will be described with reference to FIGS. 3a to 3e. First, FIG. 3a illustrates a method of generating a simulated waveform Wp when the accident point Pf and the measurement point Ps are different. Here, it is assumed that there are a plurality of reflection points Pr in the front (right) direction and the rear (left) direction of the accident point Pf, and the measurement points Ps exist adjacent to the rear of the accident point Pf. In the case of this positional relationship, surge measurement is performed at the measurement points Ps at times t1, t2, and t3. Therefore, conversely, a simulated waveform Wp in which the direct wave Wd and the reflected wave Wr appear as surge waveforms at times t1, t2, and t3 is created, and if this is similar to the measured waveform Ws, the accident point is specified in Pf. Can be done. In this notation, the solid line represents the propagation path of the direct wave Wd, and the dotted line represents the propagation path of the reflected wave Wr.

FIG. 3b illustrates a method of generating a simulated waveform Wp when there are two measurement points. Here, there are a plurality of reflection points Pr and a plurality of measurement points Ps in the front (right) direction and the rear (left) direction of the accident point Pf, respectively. In the case of this positional relationship, surge measurement is performed at time t2 and t4 at the front measurement point Ps1, and surge measurement is performed at time t1, t3 and t5 at the rear measurement point Ps2. Therefore, conversely, simulated waveforms Wp1 and Wp2 in which direct waves Wd1, Wd2 and reflected waves Wr appear as surge waveforms at times t1, t2, t3, t4 and t5 are created, and these have a similar relationship with the measured waveform Ws. For example, the accident point can be specified in Pf.

FIG. 3c illustrates a method of generating a simulated waveform Wp when the accident point Pf and the measurement point Ps are the same. In this example, the measurement point Ps is generally installed on a bus in a substation, for example, but it is assumed that an accident occurs on the bus. Here, the accident point Pf and the measurement point Ps are located at the same location, and a plurality of reflection points Pr exist in each of the front (right) direction and the rear (left) direction. In the case of this positional relationship, surge measurement is performed at the measurement points Ps at times t1, t2, t3, t4, and t5. Therefore, conversely, a simulated waveform Wp in which the direct wave Wd and the reflected wave Wr appear as surge waveforms at times t1, t2, t3, t4, and t5 is created, and if these are similar to the measured waveform Ws, the accident point is determined. It can be specified as Pf.

The above cases (FIGS. 3a to 3c) assume the case of FIG. 1a (when a surge occurs at the accident point) in which the accident point is determined when an accident occurs in the power system. On the other hand, the case of FIG. 1b (surge occurs at the injection point) is a case of artificially injecting a pulse during the continuation of the accident, and FIG. 3d illustrates a method of generating a simulated waveform.

In the example of FIG. 3d, the injection point Pi and the measurement point Ps are, for example, work places near the accident site, which are set to substantially the same point, and a plurality of reflection points including the front accident point and the rear reflection point. The reflected waves from are sequentially obtained. In this case, since the injection point Pi and the measurement point Ps are at the same location, all of them are reflected waves, but the first surge is treated as a direct wave Wd. In the case of this positional relationship, surge measurement is performed at the measurement points Ps at times t1, t2, t3, t4, and t5. Therefore, conversely, a simulated waveform Wp in which the direct wave Wd and the reflected wave Wr appear as surge waveforms at times t1, t2, t3, t4, and t5 is created, and if these are similar to the measured waveform Ws, the accident point is determined. It can be specified as Pf.

In the example of FIG. 3e, the system configuration is basically the same as that of FIG. 3a, and the positions of the points are the same, but the line types of the power transmission lines are different in front of and behind the reflection point Prf1. Therefore, the reflected wave from the front at the measurement point Ps arrives at the reflected wave Wr3 later than that in FIG. 3a due to the change in the propagation speed due to the difference in the line type. Even in this case, by creating a simulated waveform that takes into account the change in propagation velocity due to the difference in line type, it is possible to determine the accident point by confirming the similarity relationship as in the case described above.

In each of the above cases, the horizontal axis indicates the positions of the accident point Pf, the reflection point Pr, and the measurement point Ps along the line of the electric power system, and the vertical axis indicates the passage of time t. The diagonal line in the figure is a surge propagation line having a relationship between the line position (horizontal axis) and time (vertical axis). The time axis t plots the passage of time after the accident occurrence time as the origin.

According to the above display, the faster the surge propagation speed, the closer the gradient of the propagation line is to horizontal, and the earlier the arrival time. On the contrary, the slower the propagation speed, the steeper the gradient of the propagation line and the later the arrival time. The propagation speed can be converted into the time width of the waveform. The faster the propagation speed of the surge, the shorter the waveform width (time width), and the slower the propagation speed of the surge, the longer the waveform width (time width).

The surge includes a direct wave Wd that travels from the accident point Pf (or injection point Pi) toward both sides of the system, and a reflected wave Wr that travels in the opposite direction at the reflection point Pr. When these surges pass the measurement point Ps, they are measured as a single surge waveform. Therefore, by arranging the single-shot waveform of the surge at the time when the direct wave Wd and the reflected wave Wr arrive at the measurement point Ps, a simulated waveform Wp that combines a plurality of single-shot waveforms is created. The surge can occur in both positive and negative directions, and the amplitude (positive and negative) of the reflected wave Wr may be inverted at the reflection point. Therefore, there is a method of taking the absolute value or the square value of the surge or the reflected wave and using it without depending on the positive or negative.

The present invention is characterized in that the combination of the direct wave Wd and the reflected wave Wr observed at the measurement point Ps in this way is generated as a simulated waveform Wp.

As described above, in the present invention, the gradient of the propagation line in the figure corresponds to the propagation speed of the surge. Therefore, when the difference in line type can be understood from the information of the system configuration, the change in the propagation speed due to the difference in the line type can be reflected as the change in the gradient of the propagation line. At this time, since it is sufficient that the ratio of the change in the propagation speed depending on the line type can be drawn as the ratio of the change in the gradient of the propagation line, it is not necessary to know the propagation speed quantitatively.

FIG. 4 shows a notation example of a single-shot waveform arranged at the surge arrival time in the above drawing procedure. FIG. 4 exemplifies an impulse-like waveform, a sinusoidal waveform, a sinusoidal waveform including a part of reverse polarity, and a triangular wave, and these waveforms may be any in the drawing of the present invention.

The waveform of the surge actually observed has a complicated shape, but in the present invention, a combination of a plurality of waves of the direct wave Wd and the reflected wave Wr is treated as a waveform instead of a single-shot waveform of the surge as described later. Therefore, the single-shot waveform used to generate the simulated waveform Wp does not have to be similar to the measured waveform Ws. For example, an instantaneous waveform known as a delta function, a square wave, a triangular wave, or the like can be used. The amplitude and waveform width of these single-shot waveforms are not limited. The narrower the waveform width of the single-shot waveform, the higher the resolution in the time axis direction, but on the other hand, it is better to have an appropriate time width to obtain stable results. Further, the amplitude of the single-shot waveform may be changed as it is attenuated as the propagation distance becomes longer.

The present invention compares the similarity of the temporal positional relationship between the direct wave Wd and the reflected wave Wr contained in the measured waveform Ws and the simulated waveform Wp, in other words, the similarity of the time interval between the direct wave Wd and the reflected wave Wr. It is calculated as similarity. The waveform width (time width) of the measured waveform Ws and the simulated waveform Wp used for calculating this similarity is not limited. For example, the waveform width may be arbitrarily set so as to include an appropriate number of single-shot waveforms. Alternatively, the line range to be targeted and the surge propagation speed are provisionally set, the surge propagation time is calculated from the conditions, and the waveforms of the measured waveform Ws and the simulated waveform Wp are included so that the surge reaching that time is included. The width (time width) may be set. At this time, the waveform width (time width) may be set in consideration of the number of reflection points included in the line range, the attenuation of the surge due to the propagation distance, and the like.

Next, as a method of creating a simulated waveform Wp, a method using a mathematical formula will be described.

By describing the procedure for generating the simulated waveform Wp by the above drawing using a mathematical formula, the simulated waveform Wp can be generated by using a program or the like. Therefore, in the above-mentioned drawing, the propagation line showing surge propagation is mathematically expressed as a linear expression related to the line direction and the time direction. The reflection point Pr and the measurement point Ps are set as line positions. The intersection of the measurement point Ps and the propagation line (primary formula) is the arrival time, and a simulated waveform Wp is generated by arranging a single waveform of surge (direct wave and reflected wave) at that time. Further, at the intersection of the reflection point Pr and the propagation line (primary equation), a propagation line (primary equation) of the reflected wave traveling in the opposite direction is generated.

In these mathematical formulas, the accident point Pf is treated as an unknown variable. Then, the accident point with the highest similarity is determined by using the index of similarity between the measured waveform Ws and the simulated waveform Wp.

An example of the procedure for generating the simulated waveform Wp is shown below.

First, set the variables and conditions used for the calculation of the orientation. Here, the starting point is appropriately set for the line position x. The initial value of the time t is set appropriately. The positions r (i) and (i = 1 to M) of the reflection points are set based on the system configuration information. The positions m (k) and (k = 1 to N) of the measurement points are set based on the system configuration information.

Next, a variable (unknown number) used for the orientation calculation is prepared. Here, the position of the accident point is Fs, the surge arrival time is Ts, and the surge propagation speed is Vs. However, here, the surge arrival time Ts is the time when the first surge arrives, and is a converted value from the above-mentioned accident occurrence time.

An example of formulating the propagation line of surge propagation using the above symbols is shown in Eq. (1). There is a method of expressing a combination of a plurality of surge propagation expressions in a matrix format, but this is omitted here.

In addition, the following rules are prepared to generate a simulated waveform using the surge propagation equation in Eq. (1). These rules "propagate the surge waveform from the accident point Pf in both directions of the line", "generate a reflected wave Wr whose direction is reversed at the intersection of the surge waveform and the reflection point Pr", and "surge waveform". And a single-shot waveform with a time width is placed at the intersection of the measurement points Ps. "

The intersection time Tr of the surge waveform and the reflection point Pr can be obtained by connecting the surge propagation equation S (t) and the position r (i) of the reflection point Pr with an equal sign and solving the time t. From this intersection time, a surge propagation equation of a new reflected wave Wr traveling in the opposite direction is created, and the calculation of the intersection time with the reflection point Pr is repeated again.

The intersection time Tm of the surge waveform and the measurement point Ps can be obtained by connecting the surge propagation equation S (t) and the position m (k) of the measurement point Ps with an equal sign and solving the time t. Using this result, a simulated waveform Wp is generated by arranging a single waveform at the time Tm at the intersection.

Here, if there is no measurement error in the measured waveform Ws and there is no error in the system configuration information used for generating the simulated waveform, the accident point Pf (or injection) can be solved analytically by combining the measured waveform Ws and the simulated waveform Wp. Point Pi) can be calculated. However, practically, the measurement waveform contains a measurement error, and the system configuration information used for generating the simulated waveform contains an error, so that it is often impossible to solve it analytically.

Therefore, in the present invention, in order to consider the error included in the measured waveform Ws and the simulated waveform Wp, a single waveform having a time width is arranged as described above, and then numerically calculated using a similarity index. Search for the accident point Pf (or injection point Pi).

In the present invention, as will be described later, the procedure of generating the simulated waveform Wp and calculating the similarity between the measured waveform Ws and the simulated waveform Wp is repeatedly calculated by using a full search or an optimization calculation to obtain the most similarity. Determine the accident point where is high.

Here, the time width of the simulated waveform Wp is not particularly limited, and the direct wave Wd and the reflected wave Wr are set to be appropriately combined. Therefore, a method of fixing the time width, a method of automatically setting the time width so that an appropriate number of direct wave Wd and reflected wave Wr are included, and the like may be used. If the calculation range is short, the calculation load is reduced but the localization accuracy is reduced, and conversely, if the time width is long, the calculation load is increased but the localization accuracy tends to be improved.

In the calculation process of this search procedure, when the accident point Pf (or injection point Pi) is correctly obtained, the similarity between the measured waveform Ws and the simulated waveform Wp is the highest, and otherwise the similarity is low. can get. For example, if the track position is on the horizontal axis and the similarity is on the vertical axis, a convex distribution characteristic having the highest similarity at the accident point position can be obtained. This distribution characteristic can be expressed as the basis for determining the accident point or as the accuracy of determining the accident point.

Next, the calculation of the similarity between the measured waveform Ws and the simulated waveform Wp will be described.

The present invention includes a procedure for calculating the similarity between the measured waveform Ws and the simulated waveform Wp. In the field of geometry, when considering the similarity between two figures, the term "similarity" is used as an index regardless of the orientation and size of the figures. In the present invention, the similarity between the measured waveform Ws and the simulated waveform Wp is calculated as a similarity in order to consider the similarity regardless of the start point and width (time width) of the waveform. Then, the present invention determines the accident point by utilizing the fact that the similarity between the measured waveform Ws and the simulated waveform Wp becomes the highest when the accident point can be correctly defined.

The calculation of the similarity between the measured waveform Ws and the simulated waveform Wp will be described with reference to FIG. Here, the time-series information of the measured waveform Ws is represented by X (t), and the time-series information of the simulated waveform Wp is represented by Y (t). The measured waveform X (t) is measured as a wave, but the simulated waveform Y (t) is a simulated waveform based on the accident point and is expressed as an impulse train including the wave arrival time and the propagation velocity (waveform width). ..

As shown in FIG. 5, the measured waveform Ws and the simulated waveform Wp are represented by time-series signals X (t) and Y (t) at time t. Here, the time t indicates a discrete sampling time. Therefore, it may be replaced in the order of discrete sampling. Examples of the similarity calculation method are shown in the following equations (2), (3), and (4). Here, the symbol Σ (sigma) indicates addition for time t.

Similarity 1 shown in equation (2) is the addition of X (t) and Y (t) at the same time repeatedly in the time axis direction within the set time width T (t = 0 to T). By doing so, the similarity is calculated. This formula is equivalent to the formula for calculating the correlation, and the more similar the two are, the larger the value can be obtained. Therefore, the relationship between the accident point Pf and the similarity is calculated, and when the similarity is the highest, the accident point Pf can be calculated correctly.

The similarity 2 shown in the equation (3) is a modification of the calculation equation of the similarity 1, and shows a case where the similarity is calculated after converting X (t) and Y (t) at the same time into positive values. .. There are methods such as square and absolute value to take a positive value. Here, the method of taking an absolute value is shown. This calculation formula can calculate the similarity focusing on the positional relationship even when the amplitude (positive or negative) of the reflected wave is inverted.

Similarity 3 shown in equation (4) is similar by repeating the calculation of squared the difference between X (t) and Y (t) at the same time within the set time width and adding them repeatedly to the time axis method. Calculate sex. The square is to create a positive value, and the absolute value may be taken instead. The denominator of this formula is equivalent to the formula for calculating the squared error, and the smaller the value is, the smaller the value is, so the formula used as the similarity is shown by taking the reciprocal of the value.

The present invention does not evaluate the similarity of a single-shot waveform of a surge, but evaluates a waveform in which a direct wave Wd and a reflected wave Wr are combined as a simulated waveform Wp. Therefore, the single-shot waveform used to generate the simulated waveform Wp need not be similar to the single-shot waveform included in the measured waveform Ws. For example, the single-shot waveform for creating the simulated waveform Wp may be a binary square wave of 0 and 1. At this time, for example, the similarity 2 of the equation (3) can be a simple calculation as shown by the equation (5) by adding the measured waveforms in the range where the simulated waveform is 1.

The above can be extended to an equation for calculating similarity using measurement waveforms Ws obtained from a plurality of measurement means. At this time, the measurement waveform Xi (t) is collected at the measurement point k (k = 1 to N) to generate the simulated waveform Yk (t) corresponding to the measurement point k (k = 1 to N). Then, the similarity is calculated using the measured waveform Xk (t) and the simulated waveform Yk (t). Examples of the calculation formulas for similarity when the formulas (1), (2), and (3) are extended are shown in the formulas (6), (7), and (8).

In these equations, the symbol Π (pi) represents the product for the measurement points k (k = 1 to N), and the symbol Σ (sigma) represents the addition for the time t (t = 0 to T). Calculation of similarity using a plurality of measurement waveforms has the effect of canceling random noise components and improving the accuracy of accident point determination.

Next, a method of calculating similarity in consideration of the start point and width (time width) of the waveform will be described. In the present invention, as shown in FIG. 6, the similarity is calculated by using the accident point, the surge arrival time, and the surge propagation speed as variables. Here, the measurement waveform X (t) shown as a wave and the simulated waveform Y (t) shown as an impulse train are superimposed and displayed as a simulated waveform based on the accident point. In addition, here, the wave arrival time and the propagation velocity (waveform width) are taken into consideration and displayed in an overlapping manner. Therefore, the variables of the simulated waveform Y (t) are the distance to the accident point, the arrival time, and the propagation speed (waveform width).

Of these variables, the accident point is the location where the surge of the simulated waveform Y (t) occurs.

The time when the surge, which is the next variable, arrives at the measurement point is the start point time of the simulated waveform Y (t). If the start point time of the waveform is Sa, the time-series signal of the simulated waveform Y (t) can be expressed as Y (t—Sa).

The last variable, the surge propagation velocity, is reflected in the waveform width. If the propagation speed is Sv, the time-series signal of the simulated waveform Y (t) can be expressed as Y (Sv · t). If the propagation speed Sv is large (if the propagation speed is fast), the waveform width becomes short corresponding to accelerating the time of the simulated waveform Y (t), and conversely if the propagation speed Sv is small (if the propagation speed is slow) ) The waveform width becomes longer corresponding to delaying the time of the simulated waveform Y (t).

As described above, in the present invention, since the similarity is calculated for the entire waveforms of the measured waveform X (t) and the simulated waveform Y (t), the influence of noise, waveform distortion, and the like is reduced. In other words, the calculation procedure itself of the present invention has the effect of removing noise. Therefore, noise removal for the measured waveform and preprocessing such as a frequency filter are not required, or even when using it, a simple calculation is sufficient, which is effective in reducing the processing load.

Next, the search procedure by numerical calculation will be described. In order to search for the accident point where the measured waveform X (t) and the simulated waveform Y (t) are most similar by numerical calculation, the accident point, surge arrival time, and surge propagation speed are prepared as unknown variables.

FIG. 7 illustrates the relationship between the accident point and the similarity when focusing only on the accident point among the above variables. The relationship between the accident point and the similarity is the highest when the accident point is set correctly, and the similarity decreases toward the vicinity of the accident point, resulting in a distribution characteristic centered on the accident point. Similarly, regarding the relationship between the three unknown variables and the similarity, the value of the variable is determined by numerical calculation by utilizing the fact that the similarity between the simulated waveform and the measured waveform becomes the highest when it can be estimated correctly.

In the above description, the system configuration information which is known information and the accident point information which is unknown information are used to generate the simulated waveform Wp. Here, the system configuration information is information on the system configuration including the reflection point, and the accident point information is the accident point, surge arrival time, and surge propagation speed, which are unknown variables. Then, in the generation of the simulated waveform Wp, a plurality of accident points are provisionally set, and a plurality of simulated waveforms Wp in which the surge arrival time and the surge propagation speed are unknown are obtained.

Each of the above processes can be realized in the flowchart of FIG. The present invention does not limit the search method by numerical calculation, and a calculation method such as an optimization calculation can be used for a full search or for speeding up. This search method will be determined in consideration of the calculation load, the validity of the search result, the stability of the search procedure, and the like.

For example, when searching by the full search method, create a triple loop that repeatedly calculates while changing the above-mentioned unknown variables, the accident point position, the surge arrival time, and the surge propagation speed, and determine the similarity within each loop. Calculate and detect the variable with the highest similarity. The method of performing loop calculation covering the range of variables that can be taken in this way increases the calculation load, but there is no omission in the search, and the validity and stability of the result are excellent.

Further, the present invention does not limit the method and procedure of the optimization calculation. For example, when applying PSO (particle swarm optimization method) to the present invention, solution candidates are set in a space whose coordinate axes are the position of the accident point, the arrival time of the surge, and the propagation speed of the surge, and the most similarity is achieved. Will be searched for solution candidates that increase. Then, the end of the search is determined by preparing some end condition for the iterative calculation of the search, the iterative calculation is completed, and the result is output. By using the optimization calculation, the effect of reducing the calculation load can be obtained as compared with the full search.

In the first embodiment, the overall description of the present invention and the case where a surge is generated at the accident point in FIG. 1a will be mainly described. On the other hand, in the second embodiment, the case where the pulse injection of FIG. 1b is performed will be described in detail.

The pulse injection method is used in the scene of site search to identify the detailed position of the accident point when the worker arrives near the site at the stage where the accident cannot be removed after the accident occurs and the accident continues. Often.

As one of the embodiments of the present invention, a surge can be generated and an accident point can be defined by injecting a pulse into a line using an external device after an accident occurs.

In this method, the pulse injection point Pi becomes the surge generation point, and the accident point Pf becomes the surge reflection point Pr. Then, a simulated waveform Wp is generated for the surge generated and propagated at the pulse injection point Pi in the same manner as described above, and the accident point can be defined by searching for the similarity between the measured waveform Ws and the simulated waveform Wp. ..

In this method, after an accident occurs, a surge is generated at an appropriate point on the line as a pulse injection point. The present invention does not limit the principle of injecting a pulse, the device configuration, the working method, and the like. A surge can be generated by injecting a pulse by means such as electrode contact or electromagnetic induction. In addition, a surge can be generated by switching devices such as SVRs, SVCs, switches, etc. installed on the track. These devices may be used not only after the occurrence of an accident but also to detect changes in the system state by generating and measuring surges at appropriate timings when they are healthy.

The present invention defines the accident point Pf using the processing flow procedure shown in FIG.

First, in the processing step S11, the pulse injection point Pi and the measurement point Ps are set on the target line. Both may be installed at the same location, but in situations where this method is applied, it is better to install them at the site.

Next, in the processing step S12, a pulse is injected and the measurement waveform Ws is collected.

Next, in the processing step S13, a simulated waveform Wp is generated based on the information of the set pulse injection point and measurement point, and the target system configuration. This process can be realized by applying the process of process step S4 of FIG.

Finally, in the processing step S14, the accident point is defined by using the similarity between the measured waveform Ws and the simulated waveform Wp. This process can be realized by applying the processes of the process steps S6 and S7 of FIG.

According to the accident point setting method according to the second embodiment of the present invention, "the accident point can be set after the accident occurs", "any point can be set as a pulse injection point and a measurement point", and "a plurality of times of setting". By repeating the work, it becomes possible to narrow down the accident points. ”“ Existing equipment such as SVRs, SVCs, switches, etc. installed on the track can be used as a means of pulse injection (surge generation). ] And other effects can be obtained.

It is a laborious and time-consuming task to patrol the track where the measuring instrument is not installed and search for the accident point. On the other hand, the accident point locating method by pulse injection according to the second embodiment of the present invention has an effect of reducing manpower and time required for searching for an accident point after an accident occurs.

In Example 3, the handling of the reflection point Pr will be described. This is the handling of the new generation or disappearance of the reflection point Pr.

As described above, the impedance mismatched points that serve as the reflection points Pr of the surge include branch points, insulators, and the like. In addition, the reflection point Pr may be generated or extinguished for some reason. For example, a portion where the insulation resistance decreases may occur as a new reflection point Pr due to a change in characteristics due to aged deterioration. In addition, impedance mismatch may occur or disappear due to temporary contact with another object. It is possible to use it as a prior alarm as a concern that the supply reliability may be lowered even if an accident does not occur, because the generation and disappearance of the reflection point Pr suggests some change in the system state.

According to the present invention, the generation and disappearance of the reflection point Pr can be detected from the change in the surge measurement waveform Ws. The accident point locating technique of the present invention can be applied to "positioning a place where a reflection point is generated and disappearing" and "setting an accident point that has occurred in a situation where a reflection point is generated and disappearing".

The localization method using the pulse injection method will be described below. Method 1 in this case is to output an alarm.

When the current measurement waveform is compared with the previously measured waveform and a change in the reflection point is detected although no accident has occurred, it is determined that a new reflection point has occurred. Then, the location of the new reflection point is calculated using the above-mentioned accident point positioning method.

For example, a new reflection point may be generated due to temporary contact with a tree, and there is a concern that an accident may occur due to repeated contact. In order to eliminate the cause of the accident, the occurrence of a new reflection point can be output as an alarm.

Method 2 in this case is narrowing down the accident points after the accident. After the occurrence of the accident is detected, the measurement waveform of the surge is collected by the pulse injection method, and the location of the newly generated reflection point is defined by using the above-mentioned accident point mapping. By repeatedly injecting pulses and determining the accident point, the accident point can be gradually narrowed down.

In the third embodiment of the present invention, the accident point is determined by utilizing the similarity of the entire simulated waveform, so that the determination can be performed even if some reflection points are missing or added to the generation of the simulated waveform.

In the fourth embodiment, it will be described that the calculation process related to the generation of the simulated waveform Wp and the accident point determination is speeded up and calculated.

In the accident point positioning method of the present invention, the similarity is repeatedly calculated with the accident point, the accident occurrence time (surge arrival time), and the surge propagation speed as variables until the end condition is satisfied. This iterative calculation can be realized by using the optimization calculation. Although the method of optimization calculation is not limited, there is, for example, PSO (particle swarm optimization method).

For the sake of simplicity, if the surge arrival time is set to 0, the accident point and the surge propagation speed are two unknown variables. Variables (accident point and surge propagation speed) are set in the iterative calculation, a simulated waveform is generated by the method described above, and the similarity with the measured waveform is calculated. Then, the two variables with the highest similarity (accident point and surge propagation velocity) are searched. Judgment is made as the end condition of the iterative calculation, such as when the similarity becomes larger than a certain value, when the change in similarity becomes smaller than a certain value, or when the number of repeated calculations becomes more than a certain value. ..

In the fifth embodiment, the device configuration of the power system monitoring device of the present invention will be described. In particular, a configuration for data transmission between the slave station and the server will be described.

FIG. 9 shows an example of a device configuration of a power system monitoring device for carrying out the present invention. The device configuration will be determined based on criteria such as processing time, cost, amount of transmitted data, and the like.

In FIG. 9, the waveform is measured at the measurement point of the power system (in the illustrated example, the installation point of the switch with a sensor is shown), and the measurement waveform data is obtained on the server side via a network or the like, and a predetermined value is obtained. Display the processing result on the screen.

When examining the device configuration for carrying out the present invention, the main elemental functions for realizing this are the measurement waveform input means, the simulated waveform generation means, the similarity calculation means, and the accident point at which the similarity is highest. It can be said that it is a means to determine.

These means can be distributed and arranged in the slave station and the base server. Here, the base server refers to a centralized monitoring and control device such as a power distribution automation system. The distributed arrangement method will be determined in consideration of the device cost, processing time, and the like. In the case of distributed arrangement, a data transmission means for exchanging data between the two is prepared.

As one of the configuration examples, there is a method of arranging all of the above means on the slave station side. In this configuration, only the localization result needs to be transmitted to the base server side, and the amount of data transmission can be reduced. Further, the processing load on the slave station side can be reduced by generating the simulated waveform on the base server side and transmitting it to the slave station side.

As another configuration example, there is a method in which the waveform data measured on the slave station side is transmitted to the base server side, and the server side performs the standardization using the measured waveform and the simulated waveform. This configuration enables signal processing that utilizes the computing power of the server side, and can reduce the burden on the slave station side. Further, by aggregating the surge waveforms measured at a plurality of points, it is possible to improve the positioning accuracy.

Further, there is a method of configuring as a portable accident point locating device without using the above-mentioned slave station and base server. By providing the pulse injection means, a surge is generated at an arbitrary point after the accident and the accident point is defined. It can be used for detailed search in the vicinity of the accident, and also for confirming the removal of accident points after accident recovery work. As a pulse injection method, there is a method of bringing an electrode into contact with an electric wire. In order to collect the measurement waveform, there is a method of bringing the electrode into contact with the electric wire. In order to improve workability, the measurement waveform can be collected by setting the pulse injection point and the measurement point at the same point. Then, a simulated waveform can be generated using the information of the reflection points in the vicinity, and the accident point can be determined using the similarity between the measured waveform and the simulated waveform. By making it a portable device, it is possible to set an arbitrary timing and an arbitrary place after an accident occurs and repeat the positioning to gradually narrow down the accident points.

In the sixth embodiment, the output of the localization result and how to use it will be described.

FIG. 10 shows an example of a screen configuration for displaying the result of accident point determination of the present invention. Here, an example is shown in which the person in charge of restoration work is presented with the result of locating the accident point, the basis of the scoring result, and the accuracy of scoring.

The basis of the orientation can be shown by temporarily storing and presenting the progress data of the search procedure for determining the accident point having the highest similarity. In many cases, the relationship between the position of the accident point and the similarity is a distribution characteristic centered on the accident point where the similarity is highest. Presenting the relationship between the accident point and the similarity will help the operator who uses the orientation result to show the basis and accuracy of the orientation and help the interpretation.

Further, in the present invention, using the background of the search procedure as described above, it is possible to prepare a condition for determining that the accident point determination is impossible for some reason, and present the determination result and the basis. For this reason, the judgment conditions that make it impossible to determine the accident point are "distortion of the measurement waveform, large noise, and localization accuracy cannot be obtained" and "measurement in which there are no reflection points on the line and direct waves and reflected waves are superimposed. Prepare waveforms, simulated waveforms cannot be obtained, "there are an extremely large number of reflection points on the line, and the reflected waves overlap to form an averaged waveform."

The present invention determines that immobilization is impossible using the above conditions. The threshold value used for this determination may be fixedly set in advance, or may be set according to the characteristics of the target system. It can be used as a guideline for how to proceed with restoration work by outputting the result of determining whether or not the accident point can be set along with the result of setting the accident point.

In the seventh embodiment, determination of the presence or absence of an accident point will be described. It will be described that the presence or absence of the accident point of the target system is determined by using the accident point setting by this invention.

In the above-mentioned accident point determination by pulse injection, the direct wave of the surge generated by the pulse injection, the reflected wave from the reflection point on the line, and the reflected wave reflected at the accident point are collected as measurement waveforms. On the other hand, the simulated waveform is generated by combining the injection point for pulse injection and the reflection point set from the system configuration information with the accident point as a variable. If the accident point is not set when generating the simulated waveform, a surge waveform propagating through a healthy line can be generated.

When the measured waveform has the highest similarity to the simulated waveform created without setting the accident point, it is determined that the target line is sound (no accident point). By outputting these determination results, it is possible to support the determination of the necessity of restoration work.

In this way, the method of determining the presence or absence of an accident point using the accident point marking is "confirmation of accident point removal by accident recovery work" and "presence or absence of obstacles (accident points) in the partial system separated by using a switch or the like". It can be used for "confirmation of" etc.

For example, for a partial system (or microgrid) that was separated from the system using a switch when an accident occurred, it was confirmed that there were no accident points in the system or that the accident points had been removed before attempting to recover from a power failure. The above procedure can be used to do so.

As described above, the present invention can be used as a method for confirming that there is no accident point in the target system in order to start power recovery after the accident.

Claims (13)

A power system monitoring device that uses surges in the power system to identify accident points.
The first means of measuring the surge waveform propagating in the power system to obtain the measured waveform,
A second means for simulating a surge waveform propagating in the power system based on the system configuration information and the accident point information of the power system and obtaining the simulated waveform.
A third means for determining the similarity between the measured waveform and the simulated waveform and determining the accident point,
A fourth means of outputting the marking result of the marked accident point,
A power system monitoring device characterized by being equipped with. The power system monitoring device according to claim 1.
The first means is a power system monitoring device characterized in that a surge waveform generated at an accident point in a power system is measured to obtain a measured waveform. The power system monitoring device according to claim 1.
A power system monitoring device characterized in that a surge is injected into a power system and the first means measures a surge waveform due to the injected surge. The power system monitoring device according to any one of claims 1 to 3.
The measurement waveform and the simulated waveform are power system monitoring devices characterized in that they are a waveform sequence in which a plurality of single-shot waveforms are combined in a time series. The power system monitoring device according to any one of claims 1 to 4.
The system configuration information is information on the system configuration including known reflection points, and the accident point information is a power system monitoring device characterized by unknown variables such as an accident point, a surge arrival time, and a surge propagation speed. .. The power system monitoring device according to claim 5.
A power system monitoring device characterized in that a plurality of accident points are temporarily set in the generation of the simulated waveform, and a plurality of simulated waveforms in which the surge arrival time and the surge propagation speed are unknown are obtained. The power system monitoring device according to any one of claims 1 to 6.
The power system monitoring device is characterized in that the system configuration information of the power system includes information on reflection points and includes means for determining the presence or absence of newly generated or disappeared reflection points. The power system monitoring device according to any one of claims 1 to 7.
A processing device composed of the second means and the third means is provided with a data transmission means between the first means or the fourth means, and data is exchanged between the two means. Power system monitoring device. The power system monitoring device according to any one of claims 1 to 8.
The fourth means is a power system monitoring device characterized in that the grounding result of the accident point and the estimation accuracy of the grounding result are output together. The power system monitoring device according to any one of claims 1 to 9.
The fourth means is a power system monitoring device characterized in that the accident point, surge arrival time, and surge propagation speed are output as the determination result of the accident point. A power system monitoring method that uses surges in the power system to identify accident points.
Obtain the measured waveform by measuring the surge waveform propagating in the power system.
Based on the system configuration information and the accident point information of the power system, a surge waveform propagating in the power system is simulated and generated to obtain a simulated waveform.
Judging the similarity between the measured waveform and the simulated waveform, the accident point is defined, and
A power system monitoring method characterized by outputting the marking result of the marked accident point. The power system monitoring method according to claim 11.
A power system monitoring method characterized in that a surge propagation path is drawn on a plane of position and time on the power system in order to obtain the simulated waveform. The power system monitoring method according to claim 11.
A power system monitoring method characterized by executing a numerical analysis method using a mathematical formula based on known system configuration information and unknown accident point information in order to obtain the simulated waveform.

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