Accident location device and method

Abstract

To provide a fault location device and method that can expand the range in which fault locations can be located while suppressing increases in costs. [Solution] The fault location device 1 for locating a fault point FP in a power system 3 includes a waveform input unit 14 that receives waveforms measured by a sensor 2 installed in the fault-causing power system where the fault occurred, and waveforms measured by a sensor installed in a predetermined power system that has a predetermined relationship with the fault-causing power system, and a fault location calculation unit 15 that calculates the location of the fault point based on the waveforms obtained from the waveform input unit.

Description

Technical Field

[0001] The present invention relates to an accident point calibration device and method.

Background Art

[0002] The power system is a large-scale system constructed and operated by combining many means and methods for the stable supply of electric power. The power system includes a power transmission system and a power distribution system. Since the power distribution system has a wide area, accidents such as ground faults may occur due to various external factors. Hereinafter, ground faults and short-circuit accidents are collectively referred to simply as accidents.

[0003] For example, when an accident occurs in the power distribution system, the protection relay installed in the power distribution system operates, and the power supply is temporarily stopped. At that time, it is important to promptly start the restoration work in order to improve the reliability of the power supply. For this purpose, it is required to promptly grasp the accident details such as the location where the accident occurred and the cause of the accident. Currently, the accident point and the cause of the accident are specified by a patrol operation by field workers. When there is no information about the accident occurrence location, it is necessary to patrol a range of up to several kilometers, so the start of the restoration work is delayed by that amount, and the power outage state lasts longer.

[0004] In recent years, due to the progress of communication networks and digital signal processing, technologies have been proposed in which sensors are installed in the power system and the system state is estimated using sensor measurement signals. In these technologies, the technology for estimating the accident point is called accident point calibration. In the prior art, accident point calibration methods such as the surge time difference method and the frequency method have been proposed.

[0005] In the surge time difference method, sensors synchronized with GPS (Global Positioning System) or high-speed communication are installed at both ends of the line, and the time it takes for the fault surge, emitted bidirectionally from the fault point to the distribution system, to reach the sensors is measured. Surges, also known as traveling waves, are known to propagate at speeds close to the speed of light in overhead lines, so the fault point can be determined from the difference in arrival times at the sensors at both ends.

[0006] The advantage of the surge time difference method is that it can determine the location using the same principle regardless of the level of ground fault resistance. When sensors with high sampling frequencies of several tens of MHz or more are installed, the location error becomes small, to several tens of meters. On the other hand, the disadvantage of the surge time difference method is that it requires at least two sensors capable of measuring at high sampling frequencies and equipped with GPS functionality for each power distribution system, resulting in high capital investment costs. Furthermore, with the surge time difference method, the location of an accident can only be determined within the range enclosed by these multiple sensors; if an accident occurs outside this range, the location of the accident cannot be determined. For example, if the aforementioned sensors are installed on switches on the main line (hereinafter referred to as the main line), the accident point cannot be determined on branch lines or in the final section. In the case of radial power distribution systems, there are many branch lines, which presents the challenge of a high proportion of accidents that cannot be pinpointed.

[0007] An example of an existing solution to the above problem is disclosed in Patent Document 1, which involves installing additional sensors on the branch line. Patent Document 1 describes a method that uses zero-sequence current or zero-sequence voltage waveforms obtained by measuring fault surges at three or more different locations.

[0008] Furthermore, in simulation-based research, a method has been studied that uses the arrival time of reflected surge waves reflected at the end of the power system, in order to overcome the shortcomings of the above surge time difference method (Patent Document 2). [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2021-92498 [Patent Document 2] Japanese Patent Publication No. 2021-50954 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] However, the method described in Patent Document 1 requires the installation of additional sensors on each branch line, which increases the manufacturing and maintenance costs of the fault location device.

[0011] The technology described in Patent Document 2 utilizes reflected waves from surges reflected at the end of the power system. However, in real-world power distribution systems, there are numerous points of impedance change, such as the connection points between cables and overhead lines, making the method using reflected waves impractical.

[0012] When using the surge time difference method, if sensors are installed at the end of each branch line, it becomes possible to pinpoint accidents occurring on the branch lines. However, this increases the number of sensors required to pinpoint the accident location, thus increasing costs.

[0013] Therefore, this disclosure provides an accident point location device and method that can expand the range in which accident points can be located while suppressing an increase in costs. [Means for solving the problem]

[0014] To solve the above problems, a fault location device according to one aspect of this disclosure is a fault location device for locating a fault location in a power system, comprising: a waveform input unit that receives a waveform measured by a sensor installed in the fault-occurring power system where the fault occurred and a waveform measured by a sensor installed in a predetermined power system that has a predetermined relationship with the fault-occurring power system; and a fault location calculation unit that calculates the position of the fault location based on the waveforms obtained from the waveform input unit. [Effects of the Invention]

[0015] According to the present disclosure, the position of the accident point can be calculated based on the waveform measured by the sensor installed in the accident-occurring power system and the waveform measured by the sensor installed in a predetermined power system having a predetermined relationship with the accident-occurring power system.

Brief Description of the Drawings

[0016] [Figure 1] Overall configuration diagram of the accident point calibration device. [Figure 2] Configuration diagram of the power system. [Figure 3] Processing flow at the time of accident occurrence. [Figure 4] Diagram showing details of step S106 in FIG. 3. [Figure 5] Determination example of step S102 in FIG. 3. [Figure 6] Another determination example of step S102 in FIG. 3. [Figure 7] Still another determination example of step S102 in FIG. 3. [Figure 8] Management table for extracting power systems having a predetermined relationship from a plurality of power systems. [Figure 9] Graph showing a method for determining the time when a surge arrives at a sensor. [Figure 10] Graph showing another method for determining the time when a surge arrives at a sensor. [Figure 11] Explanatory diagram showing the state where an accident occurs on a branch line and a method for calculating the distance from the sensor to the accident point. [Figure 12] Configuration diagram of the power system related to the accident point calibration device of Example 2. [Figure 13] Processing flow at the time of accident occurrence. [Figure 14] Configuration diagram of the power system related to the accident point calibration device of Example 3.

Modes for Carrying Out the Invention

[0017] The present disclosure will be described below with reference to the drawings. The fault location device of the present disclosure effectively utilizes a group of sensors installed in a power system to identify the location of a fault occurring in that power system. When a fault occurs in a power system, the fault location device of the present disclosure identifies the location of the fault by flanking the point of the fault with a plurality of sensors directly installed in that power system.

[0018] Alternatively, the fault location device of this disclosure identifies the location of a fault when a fault occurs in a power system by sandwiching the fault point between one of a plurality of sensors directly installed in that power system and another sensor selected from among other sensors installed in another power system that has a predetermined relationship with the power system where the fault occurred. That is, one sensor is selected from among a plurality of sensors installed in another power system that has a predetermined relationship with the power system where the fault occurred, so as to be able to sandwich the fault point with any of the sensors installed in the power system where the fault occurred.

[0019] A predetermined power system that has a predetermined relationship with the power system where the accident occurred is, for example, a power system that lies within a predetermined range from the power system where the accident occurred. In other words, a predetermined power system is a healthy power system separate from the power system where the accident occurred, and the probability of physical phenomena caused by the accident occurring is greater than a predetermined value. Alternatively, a predetermined power system is a healthy power system separate from the power system where the accident occurred, and it is in a physical relationship with the power system where physical phenomena caused by the accident occur. A physical relationship means, for example, an electrically connected relationship with an electrical device such as a switch or protective relay, or a healthy power system that can be electrically connected to the power system where the accident occurred via capacitance between the power system and the ground. A physical phenomenon caused by the accident is, for example, a surge.

[0020] The fault location device of this disclosure can also be described, for example, as follows. However, the following description does not narrow the scope of the fault location device of this disclosure.

[0021] "An accident location locating device for estimating the location of an accident in a power supply feeder when an accident occurs in a feeder where a group of sensors installed on the accident-occurring feeder cannot pinch the accident, the accident location locating device comprising: a waveform input unit that inputs measurement waveforms from sensors installed on the feeder and measurement waveforms from sensors installed on healthy feeders other than the accident-occurring feeder; a location result calculation unit that calculates the accident location based on the arrival time of the recorded accident surge; and a display unit that displays the accident location." According to the fault location device of this disclosure, even when only measurement waveforms from sensors installed at both ends of each main line can be used, it is possible to locate faults occurring on branch lines or on the final section connected to adjacent feeders via normally open switches.

[0022] The fault location device of this disclosure can locate a fault on a branch line or final section by using a waveform obtained by measuring a fault surge propagating from the branch line or final section where the fault occurred to an adjacent feeder via a normally open switch. [Examples]

[0023] Example 1 will be explained using Figures 1 to 11. The examples described below are not intended to limit the invention as claimed, and not all of the elements and combinations thereof described in the examples are necessarily essential to the solution of the invention.

[0024] In the following explanation, various types of information may be described using the expression "aaa table," but these types of information may also be represented by data structures other than tables. To indicate that the information is independent of the data structure, "aaa table" can be called "aaa information." Also, in the following explanation, processing may be described using the computer as the subject, but this indicates that these processing operations are performed by the processor (e.g., CPU (Central Processing Unit)) of the control device that the computer possesses.

[0025] Similarly, when describing a process using the device as the subject, it indicates that the process is being performed by the controller provided by the device. Furthermore, at least one of the control device and controller may be the processor itself, or it may include hardware circuits that perform some or all of the processing performed by the control device or controller. The program may be installed from the program source to each computer or device. The program source may be, for example, a program distribution server or storage media.

[0026] In the following explanation, IDs may be used as identifiers for elements, but other types of identifiers may be used instead or in addition.

[0027] The following describes embodiments of the fault location device 1 and its method based on the drawings. Note that the range of the fault location device 1 is not limited by these embodiments. Furthermore, each embodiment can be combined as appropriate.

[0028] Power system technology is sometimes explained by dividing it into distribution systems and transmission systems. The following explanation will focus on distribution systems, but fault location device 1 is also applicable to transmission systems.

[0029] In power systems, voltage and / or current (voltage-current) changes can occur due to factors such as ground faults, short circuits, and open circuits. Transient changes in voltage and / or current that occur immediately after an accident are called surges. Surges are also called traveling waves and can propagate along power lines at speeds as fast as light.

[0030] In this embodiment, surges that occur when a fault is detected based on changes in voltage and current using equipment installed in a power system are sometimes referred to as fault surges. Surges that occur due to the same causes as a fault, but are not detected as a fault, are sometimes referred to as precursor surges in this embodiment.

[0031] Accidental surges and precursory surges, despite differences in wave height or duration, may be caused by common factors and share common characteristics. This embodiment is applicable to both accidental surges and precursory surges. In the following description, accidental surges and precursory surges may be referred to simply as accidental surges or surges without distinction.

[0032] Figure 1 is an explanatory diagram illustrating a scenario in which a fault occurs in the power distribution system 3. Figure 1 shows an example of the overall configuration of the fault location device 1. The power distribution system comprises at least one main line 3-1, 3-2 and at least one branch line 3-3. Figure 1 shows two main lines 3-1, 3-2 and one branch line 3-3. Branch line 3-3 connects one main line 3-1 and the other main line 3-2 via a switch 4. Since switch 4 is a normally open switch, main lines 3-1 and 3-2 are not normally electrically connected. When switch 4 is closed, main lines 3-1 and 3-2 are electrically connected. Unless otherwise specified, the main lines and branch lines together are sometimes referred to as power distribution system 3.

[0033] Multiple sensors 2-1, 2-2, 2-3, and 2-4 are installed in the power distribution system 3. Specifically, a sensor is provided at each end of one main line. In the example in Figure 1, sensors 2-1 and 2-2 are provided at both ends of one main line 3-1. Sensors 2-3 and 2-4 are provided at both ends of the other main line 3-2. Unless otherwise specified, sensors 2-1, 2-2, 2-3, and 2-4 may be abbreviated as sensor 2. Each sensor 2 is connected to the fault location device 1 via a communication network CN, such as an optical fiber network, enabling bidirectional communication.

[0034] In the power distribution system 3 shown in Figure 1, let's assume that, for example, two faults occur at different times in two different locations. Let's assume that the locations of these faults are fault points FP1 and FP2. Figure 1 shows fault point FP1 on the main line 3-1 of power distribution system 3, and fault point FP2 on the branch line 3-3 that connects main line 3-1 and main line 3-2.

[0035] This section describes an accident on main line 3-1. As accident surges SV1 and SV2, generated at accident point FP1, propagate along the track (main line) 3-1, waveform data of surges SV1 and SV2 can be collected using sensors 2-1 and 2-2 installed on track 3-1. Specifically, when a surge occurs at accident point FP1, it travels toward both ends of track 3-1. One surge SV1 travels to sensor 2-1 and is measured by sensor 2-1. The other surge SV2 travels to sensor 2-2 and is measured by sensor 2-2. In other words, since accident point FP1 on main line 3-1 is sandwiched between sensors 2-1 and 2-2, the position of accident point FP1 can be calculated from the difference between the time surge SV1 reaches sensor 2-1 and the time surge SV2 reaches sensor 2-2.

[0036] As described later, the measurement information 5 of surge SV1 measured by sensor 2-1 is transmitted from the communication network CN to the fault location device 1. Similarly, the measurement information 5 of surge SV2 measured by sensor 2-2 is also transmitted from the communication network CN to the fault location device 1. Details of the measurement information 5 will be described later.

[0037] No sensors are provided at either end of branch line 3-3. In other words, no sensors are placed where branch line 3-3 connects to main line 3-1, nor where branch line 3-3 connects to main line 3-2. Therefore, under normal circumstances, it is not possible to automatically estimate the position of fault point FP2 on branch line 3-3. In this embodiment, as will be described in detail later, it is assumed that fault point FP2 is sandwiched between sensor 2-1, which is provided at one end of one main line 3-1, and sensor 2-3, which is provided at one end of the other main line 3-2. The position of fault point FP2 on branch line 3-3 is then estimated from the arrival time of the surge measured by sensor 2-1 and the arrival time of the surge measured by sensor 2-3.

[0038] Here, the power distribution system 3 mentioned above is an example of a "power system." The distinction between main lines 3-1, 3-2 and branch line 3-3 will be explained later. The sensor 2 mentioned above is a sensor that detects and records the waveform of a surge (fault surge), which is an example of a "physical phenomenon caused by a fault," and transmits the measurement information 5 to the fault location device 1.

[0039] Sensor 2 is an electrical circuit that combines components such as a frequency filter, an analog-to-digital (AD) converter, and memory, and converts the input voltage and current analog signals into digital signals for output. Sensor 2 may also have a built-in CPU and execute processing based on a computer program.

[0040] Sensor 2 not only has the function of detecting the surge waveform as described above, but also has functions such as acquiring the time when the surge waveform was detected, detecting the position of Sensor 2, recording the detected waveform data, and transmitting the recorded waveform to the fault location device 1.

[0041] Sensor 2 can add time information to waveform data using GPS or the like. In this way, Sensor 2 generates surge measurement information 5 by associating the surge waveform data with the location where the waveform was collected (information identifying the sensor that collected the waveform) and the time the waveform was collected. Sensor 2 transmits the measurement information 5 to the fault location device 1 either spontaneously or in response to a request from the fault location device 1 whenever it detects a surge.

[0042] As described above, the measurement information 5 collected by each sensor 2 is sent to the fault location device 1 via the communication network CN. The fault location device 1 includes, for example, a calculation unit 11, a storage unit 12, a communication unit 13, a waveform input unit 14, a fault location calculation unit 15, and a result output unit 16.

[0043] The calculation unit 11 determines the fault location from the measurement information 5 by executing a predetermined computer program stored in the storage unit 12. The calculation unit 11 is not limited to a CPU (Central Processing Unit), but may also include a GPU (Graphics Processing Unit) or an ASIC (Application Specific Integrated Circuit).

[0044] The communication unit 13 receives measurement information 5 by communicating with each sensor 2. The storage unit 12 has a database and memory. The storage unit 12 stores the measurement information 5 received from each sensor 2 and information related to the system configuration. The storage unit 12 includes a main memory and an auxiliary memory.

[0045] The waveform input unit 14 reads the waveform to be used for determining the fault location from the measurement information 5 stored in the memory unit 12. Hereinafter, determining the fault location may be abbreviated as point location.

[0046] The accident location calculation unit 15 estimates the location of the accident using the information such as the read measurement information 5. The result output unit 16 outputs the location of the accident estimated by the accident location calculation unit 15 as a localization result to a monitor display (not shown) or the like. The destination of the localization result is not limited to a monitor display; for example, it may be a printer (not shown) or email (not shown). Furthermore, the localization output unit 16 may read out the localization result in an automated voice. The localization output unit 16 may also output the localization result to a screen provided by, for example, MR (Mixed Reality), AR (Augmented Reality), or VR (Virtual Reality).

[0047] The fault location device 1 is connectable to a storage medium MM. The storage medium MM is configured as, for example, a memory device, a hard disk drive, an optical disk drive, a magneto-optical disk drive, or a magnetic tape drive, and stores computer programs and data non-temporarily. The storage medium MM can transfer and store computer programs and data to the storage device 12 of the fault location device 1. It can also transfer and store computer programs and data from the storage device 12 to the storage medium MM.

[0048] As described above, in the surge time difference method, sensors 2 are installed at both ends of the line, and the arrival times t1 and t2 of the fault surge SV at each sensor 2 are calculated, thereby determining the distance x to the fault point from a predetermined formula. The predetermined formula is shown in step S106 of Figure 3. In the predetermined formula, distance L is the distance between sensors 2, and v is the propagation speed of the fault surge 5. It is known that the propagation speed of the fault surge 5 is close to the speed of light on overhead lines and about half the speed of light on cables.

[0049] The method of using the fault location device 1 will be explained in detail using Figures 2 to 11. Distribution systems 21, 31, 41, 51, etc. described below are examples of distribution system 3 described in Figure 1. Branch lines 27 and 28 are examples of branch line 3-3. Switches 24 and 25 are examples of switch 4 in Figure 1.

[0050] The power distribution system shown in Figure 2 includes a total of four power distribution systems: power distribution system 21 where the accident occurred, and three power distribution systems 31, 41, and 51 adjacent to power distribution system 21 where the accident occurred. Power distribution system 21 is an example of a "power distribution system where the accident occurred."

[0051] All distribution systems 31, 41, and 51, other than distribution system 21, are assumed to be in a healthy state without any accidents. These distribution systems 31, 41, and 51 are examples of "specified power systems" that have a predetermined relationship with distribution system 21, where the accident occurred. A single system separated by a normally open switch is sometimes called a distribution system or power supply feeder, but hereafter it will be referred to as a distribution system.

[0052] Here, the predetermined relationship refers to, for example, a power distribution system located within a predetermined range from the power distribution system 21 where the accident occurred. In other words, the predetermined relationship is a relationship in which the probability of physical phenomena caused by the accident occurring in a healthy power distribution system separate from the power distribution system where the accident occurred is greater than or equal to a predetermined value. Alternatively, the predetermined relationship is a physical relationship in which physical phenomena (surges) caused by the accident occur in a healthy power distribution system separate from the power distribution system where the accident occurred.

[0053] Other power distribution systems 31, 41, and 51 located within a predetermined range of the power distribution system 21 where the accident occurred can also be referred to as, for example, "power distribution systems adjacent to the power distribution system 21 where the accident occurred within a predetermined distance." The predetermined distance could be, for example, a few centimeters, a dozen centimeters, several tens of centimeters, a few meters, a dozen meters, or several tens of meters. These values ​​are examples only.

[0054] Furthermore, a power distribution system that has sensors that can be used to pinpoint the location of an accident by working in conjunction with sensors on the power distribution system where the accident occurred, can be called a power distribution system within a predetermined range of the power distribution system where the accident occurred.

[0055] Alternatively, if a distribution system in a predetermined relationship is defined as "a distribution system adjacent to the distribution system where the accident occurred," then an adjacent distribution system means, for example, that when a line is drawn connecting one point in one distribution system and one point in another distribution system, there are no other distribution systems on that line.

[0056] In this embodiment, we will explain the case where one power distribution system and another power distribution system are connected via a normally open switch, that is, where the predetermined distance between the two points is several tens of centimeters. However, the predetermined distance is not limited to several tens of centimeters, and may be greater.

[0057] There is a fault point 22 in the power distribution system 21. In the diagram, the gray rectangles indicate sensor-equipped switches 23, 32, 42, and 52 to which sensor 2 is installed. The black rectangles indicate normally closed switches 24, 33, 43, and 53 to which sensor 2 is not installed. The white rectangle indicates normally open switches 25. Normally open switches 25 are often installed to restore healthy sections or to resolve overloads in the event of a fault. By operating these switches, the power supply range of each power distribution system can be changed. Banks 26, 34, 44, and 54 indicate the banks in the power distribution substations to which power distribution systems 21, 31, 41, and 51 are connected.

[0058] The switches 23, 24, and 25 are not limited to switches with a mechanical switch section, but may also be electronic devices that have the function of switching between multiple states such as current flow, interruption, and partial current flow. In this specification, these are collectively referred to as switches. The sensor 2 described in Figure 1 may be installed in a different location from the switches 23, 32, 42, and 52.

[0059] In the power distribution system 21, the horizontal tracks connected to bank 26 are considered the main tracks, and these tracks are defined as the main lines. Tracks extending vertically from the main lines are branch lines. Here, in Figure 2, the horizontal direction refers to the left-right direction. In Figure 2, the vertical direction refers to the up-down direction.

[0060] The three branch lines 27 in distribution system 21 are connected to distribution system 31 or distribution system 41 via normally open switches 25. In contrast, the three branch lines 28 in distribution system 21 are not connected to any adjacent distribution system. The section further to the end of the sensor-equipped switch 23 on the main line is designated as the final section 29. The final section 29 is connected to distribution system 51 via a normally closed switch 25.

[0061] Distribution system 31 is equipped with a sensor-equipped switch 32 and a normally closed switch 33 without a sensor. Distribution system 31 is connected to bank 34. Similarly, distribution system 41 is equipped with a sensor-equipped switch 42 and a normally closed switch 43 without a sensor. Distribution system 41 is connected to bank 44. Distribution system 51 is equipped with a sensor-equipped switch 52 and a normally closed switch 53 without a sensor. Distribution system 51 is connected to bank 54. Banks 26, 34, 44, and 54 may all be different banks, or any combination may be the same bank. In this embodiment, it is assumed that they are all different banks.

[0062] Generally, in the surge time difference method, only the range enclosed by multiple sensors can be pinpointed. For example, if a fault occurs in the distribution system 21 and only the two sensor-equipped switches 23 installed in the distribution system 21 are used for pinpointing, the main line section enclosed by the two sensor-equipped switches 23 becomes the range where pinpointing is possible. Pinchpointing is not possible in the other branch lines 27, 28 and the final section 29 outside of that range. If a fault occurs in either branch line 27 or branch line 28, a normal fault point pinpointing device calculates the pinpointing result assuming that the fault occurred at the connection point between that branch line and the main line. If a fault occurs in the final section 29, a normal fault point pinpointing device calculates the pinpointing result assuming that the fault occurred near the nearest sensor-equipped switch 23 on the main line. However, the fault point pinpointing device 1 of this embodiment estimates the fault point relatively accurately by using not only sensors installed in the distribution system where the fault occurred, but also sensors installed in other distribution systems that have a predetermined relationship with the distribution system where the fault occurred.

[0063] In this embodiment, the fault location is determined using measurement information from sensors on the power distribution system where the fault occurred, as well as measurement information from sensors installed on adjacent power distribution systems.

[0064] Normally, when an accident occurs in a power distribution system, it is common practice to collect measurement values ​​from sensors installed in the distribution system and use them for fault location, without considering measurement information from adjacent healthy power distribution systems. In contrast, the inventors of this invention focused on the phenomenon that even in healthy power distribution systems, some of the accident surge can propagate by bypassing normally open switches, etc., and decided to use measurement information from adjacent power distribution systems.

[0065] As a result, for example, branch line 27 can be considered to be sandwiched between one of the sensor-equipped switches 23 and either sensor-equipped switch 32 or sensor-equipped switch 42. Then, as described above, in the area sandwiched by multiple sensors, the fault location can be determined using the surge time difference method. Therefore, this embodiment can estimate the fault location that occurred on the branch line without significantly increasing the number of sensors required.

[0066] Furthermore, in cases like branch line 28, where the end is not connected to a switch and the distance to another power distribution system is sufficiently large, it is difficult to pinpoint the fault location.

[0067] There are three possible causes for surge jumping in a normally open switch 25. The first cause is that surges propagate to the ground via the capacitance between the power distribution system and the ground, and then propagate again to another power distribution system. The capacitive impedance component due to the capacitance to ground is the reciprocal of the frequency. Therefore, at commercial frequencies, the capacitive impedance component is sufficiently large that very little current leaks into the ground. However, at high-frequency components, the capacitive impedance component becomes smaller, making surge leakage more likely. This phenomenon is sometimes called an electromagnetic interface.

[0068] The second cause is magnetic coupling. Current and voltage propagating through a transmission line can be considered as changes in the magnetic field. In normally open switches 25, adjacent power distribution systems are often only a few centimeters to tens of centimeters apart. Therefore, a change in the magnetic field from one power distribution system can affect the other, causing a change in the magnetic field and resulting in the propagation of a fault surge. This is the same principle as wireless power transmission used in electric vehicles, etc. Furthermore, if the resonator on the transmitting side and the resonator on the receiving side resonate in a magnetic field, there is a possibility that the surge will jump more significantly.

[0069] The third cause is partial discharge. When a voltage high enough to completely destroy the insulating properties of an insulator such as air is applied, the insulation breaks down and an arc is generated. However, even with an applied voltage that is significantly lower than the voltage that causes dielectric breakdown, a small discharge may occur. This is called partial discharge. Generally, manufacturers of switches conduct partial discharge tests simulating lightning impulses to evaluate the performance of their switches. If the frequency of the fault surge differs from that of the lightning impulse, unexpected partial discharge may occur.

[0070] Figure 3 shows the processing flow in the event of a fault in this embodiment. When a fault occurs in the power distribution system, the fault location device 1 acquires the zero-sequence current waveform obtained in the fault-causing system (S100). In addition to the zero-sequence current, the fault location device 1 may also acquire, for example, zero-sequence voltage, three-phase current, three-phase voltage, etc. Using the zero-sequence current waveform acquired in step S100, the fault location device 1 performs point location on the region sandwiched between sensors installed at both ends of the power distribution system (S101).

[0071] The fault location device 1 uses the location result calculated in step S101 to determine whether there is a high probability of a fault location in a branch line or final section adjacent to another power distribution system (S102). In step S102, for example, the range before and after the location is defined as the confidence range in which there is a high probability of a fault location. Then, in step S102, if the connection point between the branch line and the main line or the final section is included within the confidence range, and that branch line or final section is connected to another power distribution system via a normally open switch, the result is determined as "YES", and otherwise the result is determined as "NO".

[0072] An example of the determination in step S102 will be explained using Figures 5 to 7. The localized position 201 and its confidence range 202 are shown when using the waveforms of the sensor-equipped switches 23 installed at both ends of the track. In Example 1 shown in Figure 5, since the branch line and the final section are not included within the confidence range 202, the determination in step S102 is "NO".

[0073] In Example 2 shown in Figure 6, there is one branch line 28 within the confidence range 202. However, since this branch line 28 is not connected to another power distribution system, step S102 determines it to be "NO".

[0074] In Example 3 shown in Figure 7, one branch line 27 is included within the confidence range 202, and this branch line 27 is connected to another power distribution system outside the figure via a normally open switch 25, so step S102 is determined to be "YES".

[0075] Similarly, if the confidence range 202 includes multiple branch lines or final sections, and multiple of these are connected to other power distribution systems, step S102 will also be determined to be "YES".

[0076] Furthermore, statistical values ​​such as the standard deviation and maximum value of the targeting error can be calculated based on past targeting results, and the size of the 202 confidence interval can be determined based on these statistical values.

[0077] Return to Figure 3. If "NO" is determined in step S102, the fault location device 1 adopts the location result from step S101 and outputs the location result to a screen such as a monitor display (S108). The fault location device 1 can output, for example, Example 1 shown in Figure 4, or Example 2 shown in Figure 5, to the location result screen. The fault location device 1 may also highlight the confidence range 202 and the branch lines and final sections connected to the confidence range 202 by changing their colors.

[0078] On the other hand, if the fault location device 1 determines "YES" in step S102, it extracts the ID of the adjacent system connected by a normally open switch to the branch line or final section that is determined to be within the confidence range 202 (S103). That is, the fault location device 1 extracts the ID of the adjacent system (adjacent power distribution system; the same applies hereinafter) connected by a normally open switch to the branch line within the confidence range 202, and the ID of the adjacent system connected by a normally open switch to the final section within the confidence range 202. If there are multiple applicable branch lines or final sections, the fault location device 1 may extract the IDs of all of them, or it may extract one ID based on the distance between the location position 201 and the connection source of the branch line.

[0079] Figure 8 shows an example of a table used to extract the IDs of adjacent systems in step S103. The table in Figure 8 is an example of a "management table for extracting power systems that have a predetermined relationship."

[0080] When creating table 300, the fault location device 1 assigns an ID as identification information to all distribution systems owned by the power distribution utility. Furthermore, the fault location device 1 also assigns an ID to all branch lines and final sections present in all distribution systems. Table 300 manages, for example, the ID column 301 of the fault-occurring system, the ID column 302 of the branch line or final section, and the ID column 303 of the adjacent system in association. Additionally, table 300 may include an ID column 304 of sensors installed in the adjacent system.

[0081] Each row in table 300 corresponds to an ID column 302 of a branch line or final section, and the number of rows matches the total number of ID columns 302 for branch lines or final sections. If a branch line or final section is connected to an adjacent system with a normally open switch or the like, the ID column 303 of the adjacent system stores an ID that identifies the adjacent system. If it is not connected to any distribution system, the ID column 303 of the adjacent system is blank. The ID column 304 of a sensor installed in an adjacent system stores an ID that identifies all sensors installed in the ID column 303 of the adjacent system.

[0082] The fault location device 1 may refer to a table 300 created in advance by the business entity. The fault location device 1 may update table 300 to match the ever-changing system configuration due to system switching or other reasons. The fault location device 1 may also anticipate possible system configurations in advance and store all possible system IDs that could become adjacent systems in table 300.

[0083] Returning to the explanation of Figure 3, the fault location device 1 transmits a waveform request to a sensor installed in the adjacent system based on the information extracted in step S103 (S104).

[0084] Generally, sensors used for fault location automatically collect waveforms when a fault is detected and transmit measurement information 5 to the fault location device 1. However, in the case of adjacent systems, the fault surge propagating from the fault-generating system is small, so sensors installed in the adjacent system are unlikely to detect the fault and will not automatically transmit measurement information to the fault location device 1. Therefore, in this embodiment, if the measurement values ​​in the adjacent system are insufficient, the fault location device 1 requests the sensors installed in the adjacent system to transmit the measured waveforms to the fault location device 1. In this embodiment, this request is called a waveform request.

[0085] Sensor 2 may retain measurement information 5 for a certain period of time. To conserve memory, the sensor may retain measurement information 5 only when it measures a small disturbance, and when it receives a waveform request from fault location device 1, it may transmit the retained measurement information to fault location device 1, and discard the stored measurement information after a certain period of time has elapsed. Multiple sensors may be connected via a communication network, and if one sensor detects a fault at a certain time, other sensors associated with that sensor may automatically transmit measurement information 5 for the same time to fault location device 1. Furthermore, groups of sensors placed in each power distribution system may automatically transmit measurement information 5 to fault location device 1 periodically, regardless of whether a fault has been detected or not.

[0086] Next, when the fault location device 1 acquires measurement information 5 from multiple sensors 2 installed in adjacent systems, it selects a waveform to be used for calculating the fault location. As a method of waveform selection, the fault location device 1 can, for example, select the waveform with the least attenuation. As a method of selecting the waveform with the least attenuation, the fault location device 1 may select the sensor 2 that is considered to have the least attenuation based on the system configuration information, or it may determine the degree of attenuation from the measured waveform.

[0087] In the former method, the fault location device 1 sets coefficients related to attenuation for system equipment that affects waveform attenuation (for example, 0.5 for cable branches, 0.1 for overhead line branches, and 0.05 per 100m of overhead line). The fault location device 1 then calculates the sum or product of these coefficients along the propagation route of the fault surge from the suspected fault location to each sensor 2, and can select the sensor 2 that minimizes this value.

[0088] The latter method will be explained using Figures 9 and 10. The graphs in Figures 9 and 10 show the case where two sensors 2 are installed in adjacent systems, and the measured waveforms 401 from both sensors 2 can be acquired. The vertical axis of the graph shows the current value output by the sensor 2 when it measures the waveform, and the horizontal axis of the graph shows the number of data counts.

[0089] One method for determining the degree of attenuation from the measured waveform 401 is to determine the peak value of the amplitude 402. In this case, the fault location device 1 considers that the waveform in Figure 9 has a larger peak value of amplitude than the waveform in Figure 10, and therefore assumes that the degree of attenuation is smaller, and selects the waveform in Figure 9 as the waveform to be used for calculating the location result. However, the fault location device 1 may also calculate the degree of attenuation using the peak value of the derivative of the measured waveform 401.

[0090] If measurement information is obtained from multiple sensors 2 installed in adjacent systems, instead of selecting one of them, the measurement information from two or more sensors in adjacent systems may be used to improve the location accuracy. In this case, the same techniques as those used for location in distribution systems where more sensors than originally required are installed can be applied. In this case, for example, since the number of measured values ​​will exceed the number of unknown variables, making it difficult to solve as a system of equations, a method of creating a regression equation and obtaining the solution with the smallest error can be considered. The method of creating the regression equation is not limited. For example, the fault location device 1 may use numerical search (optimization calculation).

[0091] Returning to the explanation of Figure 3, the fault location device 1 uses the selected measurement waveform 401 and the measurement information acquired in the fault-occurring system to determine the distance x to the fault location (S105). Using the distance x calculated in step S105, the fault location device 1 estimates the location where the fault occurred (S106). Figure 4 shows the processing details of step S106.

[0092] Figure 11 shows the method for calculating distance x and an example of identifying a fault on branch line 27. In the case of a fault 22 on branch line 27, for example, it can be assumed that the fault is sandwiched between a sensor-equipped switch 23 on fault-generating system 21 and a sensor-equipped switch 32 on adjacent system 31, and the distance x can be calculated using the formula described in step S106 of Figure 3. In this case, time t1 is defined as the surge arrival time calculated using the measured waveform 401 described above, and time t2 is defined as the surge arrival time calculated using the measurement information acquired in fault-generating system 21. Distance L represents the distance between sensor-equipped switch 23 and sensor-equipped switch 32.

[0093] Return to Figure 3. The fault location device 1 determines whether or not the fault location is on the branch line (S107), and outputs the location result according to the determination result (S108).

[0094] According to this embodiment, existing sensors can be effectively utilized to expand the range over which fault locations can be determined. In this embodiment, no additional sensors are required, so performance can be improved while keeping the cost of the fault location device 1 down.

[0095] In this embodiment, by transmitting a waveform request from the fault location device 1 to a sensor 2 on a predetermined distribution system that has a predetermined relationship with the fault-occurring distribution system, the fault point can be sandwiched between the sensor 2 on the fault-occurring distribution system and the sensor 2 on the predetermined distribution system, and the location of the fault point can be calculated from the difference in surge arrival times. As a result, even if the surge appearing in the predetermined distribution system is small and the waveform measured by the sensor 2 is not automatically transmitted to the fault location device 1, the fault location device 1 can acquire measurement information from the sensor 2 within the range that may be affected by the fault point and locate the fault point.

[0096] The fault location device 1 of this embodiment includes a table 300 for extracting power distribution systems that have a predetermined relationship from among multiple power distribution systems. Therefore, the range of the sensor 2 from which measurement information should be collected can be identified in a short time, and the fault location can be quickly determined. [Examples]

[0097] Example 2 will be described using Figures 12 and 13. In each of the following examples, including this example, the differences from Example 1 described above will be the main focus.

[0098] Figure 12 shows the power distribution system assumed in Example 2. In Figure 2, two sensor-equipped switches were installed in one power distribution system. In contrast, in Figure 12, only one sensor-equipped switch is installed in one power distribution system.

[0099] For example, if a fault 22 occurs on the main line of the power distribution system 21 shown in the center of Figure 8, the fault location device 1 assumes that the fault 22 is trapped between the sensor-equipped switch 23 installed in the power distribution system 21 and the sensor-equipped switch 52 installed in the power distribution system 51, and calculates the distance x to the fault location using the formula shown in Figure 4.

[0100] Figure 13 shows the processing flow in the event of an accident in this embodiment. The accident location device 1 acquires measurement information 5 from a sensor 2 installed in the power distribution system where the accident occurred (S200), and acquires measurement information 5 from the sensor 2 in the power distribution system where the accident occurred and from a sensor 2 installed in another power distribution system adjacent to the final section of the power distribution system where the accident occurred, and determines the accident location (S201).

[0101] The fault location device 1 determines whether the fault is located in a branch line adjacent to another power distribution system or in the final section adjacent to another power distribution system (S202). If the fault location device 1 determines that a fault has occurred in a branch line or final section adjacent to another power distribution system (S202: YES), it extracts the ID of the adjacent system connected to the branch line via a normally open switch (S203). Since the sensor information for the adjacent system connected to the final section via a normally open switch has already been acquired in step S201, the ID of the adjacent system connected to the final section via a normally open switch is not acquired in step S202.

[0102] The fault location device 1 acquires additional measurement information 5 from a sensor installed in an adjacent system (S204) and calculates the distance x from the sensor in the adjacent system to the fault location (S205). The fault location device 1 estimates the location of the fault location using the distance x (S206).

[0103] The fault location device 1 determines whether or not the fault location is on the branch line (S207), and outputs the location result according to the determination result (S208).

[0104] This embodiment, configured in this way, achieves the same effects as Embodiment 1. Furthermore, in this embodiment, even if only one sensor 2 is installed in the power distribution system, it is possible to locate faults occurring in any of the power distribution systems, as well as faults occurring in branch lines connecting power distribution systems. Therefore, the fault location device 1 can be configured at a lower cost. [Examples]

[0105] Example 3 will be explained using Figure 14. In Figure 14, power distribution system 21 and power distribution system 31 are not connected by a normally open switch, but the tip of the branch line 29 extending from power distribution system 21 is at a sufficiently close distance to power distribution system 31. In this case, one of the three causes of surge jumping mentioned above is the possibility of surge leakage through the ground. Therefore, the fault point that occurred in the branch line 29 can be located using the surge time difference method.

[0106] This embodiment, configured in this way, also provides the same effects as Embodiment 1. Furthermore, in this embodiment, even if one power distribution system and another adjacent power distribution system are not connected by a normally open switch, the fault point can be determined by considering that a fault occurring in one power distribution system is sandwiched between a sensor installed in that distribution system and a sensor in the other adjacent power distribution system. Therefore, the range in which the fault point determination device 1 can determine the fault point can be expanded.

[0107] It should be noted that the present invention is not limited to the embodiments described above, and includes various modifications. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations. Moreover, each embodiment can be combined as appropriate.

[0108] The embodiments described above include the following aspects:

[0109] (Perspective 1) An accident location device that estimates the location of an accident in a power supply feeder when an accident occurs in a feeder where an accident has occurred, and which is located on a track or branch line where it is impossible to pinch the sensor group installed on the accident feeder, the accident location device comprising: a waveform input unit that inputs the measurement waveform from a sensor installed on the feeder and the measurement waveform from a sensor installed on a healthy feeder other than the accident feeder; a location result calculation unit that calculates the location of the accident based on the arrival time of the accident surge; and a display unit that displays the location of the accident.

[0110] (Perspective 2) An accident location device as shown in Perspective 1, characterized in that the healthy feeder is a feeder adjacent to the accident-occurring feeder.

[0111] (Perspective 3) A fault location device as described in Perspective 1 or 2, characterized in that the adjacent feeder is connected to the fault-generating feeder via a normally open switch or an equivalent electronic device, or the distance between the adjacent feeder and the fault-generating feeder is approximately the same as the distance when they are connected by a normally open switch.

[0112] (Perspective 4) An accident location device according to any one of Perspectives 1 to 3, characterized in that the bank to which the adjacent feeder is connected is different from the bank to which the accident-occurring feeder is connected.

[0113] (Perspective 5) A fault location device according to any one of Perspectives 1 to 4, wherein the fault location device transmits a waveform request to a sensor installed in the adjacent feeder.

[0114] (Perspective 6) An accident location device according to any one of Perspectives 1 to 5, characterized in that it holds information of adjacent feeders adjacent to or potentially adjacent to the accident-occurring feeder as a table.

[0115] (Perspective 7) A fault location device as shown in Perspective 6, wherein the table is rewritten when the adjacent feeder changes due to a system switching operation.

[0116] (Perspective 8) An accident location device according to any one of Perspectives 1 to 7, characterized in that it identifies the branch line where the accident occurred from among the main line and multiple branch lines using the measurement waveform at the accident-occurring feeder.

[0117] (Perspective 9) An accident location device according to any one of Perspectives 1 to 8, characterized in that it calculates the distance from any one of the sensors to the accident location using the difference in surge arrival times between one or more sensors installed on the accident-generating feeder and one or more sensors installed on the adjacent feeder.

[0118] (Perspective 10) A fault location device according to any one of Perspectives 1 to 9, characterized in that, when multiple sensors are installed in the adjacent feeder, the device determines which sensor's waveform to use based on the slope and amplitude of the waveforms from the sensors, the frequency bands included in the waveforms, etc.

[0119] Furthermore, the above-described embodiment discloses the following configuration.

[0120] (Note 1) A fault location device for locating a fault point in a power system, comprising: a waveform input unit that receives a waveform measured by a sensor installed in the fault-occurring power system where the fault occurred, and a waveform measured by a sensor installed in a predetermined power system that has a predetermined relationship with the fault-occurring power system; and a fault location calculation unit that calculates the position of the fault point based on the waveforms obtained from the waveform input unit.

[0121] (Note 2) The fault location calculation unit determines the location of the fault when the fault point cannot be identified by the sensors installed in the fault-occurring power system alone, by using the waveform measured by the sensors installed in the fault-occurring power system and the waveform measured by the sensors installed in the predetermined power system, as described in Note 1.

[0122] (Note 3) The accident location calculation unit detects the time at which a predetermined physical phenomenon caused by the accident is detected by a sensor based on the waveform obtained from the waveform input unit, and calculates the accident location based on the detected time, as described in Note 1 or 2.

[0123] (Appendix 4) An accident location device according to any one of Appendix 1 to 3, further comprising a result output unit for outputting the calculation results of the accident location calculation unit.

[0124] (Note 5) The specified power system is a fault location device described in any one of Notes 1 to 4 located within a specified range of the power system where the fault occurred.

[0125] (Note 6) The fault location device described in any one of Notes 1 to 4, wherein the predetermined power system is connected to the fault-occurring power system via a normally open switch.

[0126] (Note 7) A fault location device described in any one of Notes 1 to 4, which is different from the transformer bank to which the fault-causing power system is connected and the transformer bank to which the predetermined power system is connected.

[0127] (Note 8) The fault location calculation unit requests a sensor installed in the predetermined power system to transmit the measured waveform to the fault location calculation unit, as described in any one of Notes 1 to 4.

[0128] (Note 9) A fault location device according to any one of Notes 1 to 4, further comprising a storage unit for storing a management table for extracting power systems that have the predetermined relationship from among multiple power systems.

[0129] (Note 10) The management table is updated in accordance with any change in the configuration including the multiple power systems, as described in any one of Notes 1 to 9.

[0130] (Note 11) The fault location calculation unit determines the range in which the fault-causing power system exists based on the waveform measured by the sensor of the fault-causing power system, as described in any one of Notes 1 to 10.

[0131] (Note 12) The fault location calculation unit calculates the distance from one of the sensors provided in the fault-causing power system and the sensor provided in the predetermined power system to the fault location, using the difference between the surge arrival time measured by a sensor provided in the fault-causing power system and the surge arrival time measured by a sensor provided in the predetermined power system, as a predetermined physical phenomenon caused by the fault. This is the fault location location device according to any one of Notes 1 to 11.

[0132] (Note 13) The fault location calculation unit, when there are multiple sensors provided in the predetermined power system, selects which sensor's measured waveform to use based on the shape, amplitude, and frequency band included in the waveform measured by the multiple sensors, as described in any one of Notes 1 to 12.

[0133] (Note 14) A method for locating a fault point in a power system using a fault point locating device, comprising: a waveform input step in which a waveform measured by a sensor installed in a fault-causing power system where a fault has occurred and a waveform measured by a sensor installed in a predetermined power system having a predetermined relationship with the fault-causing power system are input; and a fault location calculation step in which the location of the fault is calculated based on the waveforms obtained in the waveform input step.

[0134] (Note 15) The fault location calculation step is the fault location method described in Note 14, which, when the fault location cannot be identified by the sensors installed in the fault-occurring power system alone, identifies the location where the fault occurred from the waveform measured by the sensors installed in the fault-occurring power system and the waveform measured by the sensors installed in the predetermined power system. [Explanation of symbols]

[0135] 1: Fault location device, 2: Sensor, 3: Power distribution system, 4: Normally open switch, 5: Measurement information, 11: Calculation unit, 12: Memory unit, 13: Communication unit, 14: Waveform input unit, 15: Fault location calculation unit, 16: Result output unit

Claims

1. A fault location device for locating the fault location in a power system, A waveform input unit receives waveforms measured by a sensor installed in the power system where the accident occurred, and waveforms measured by a sensor installed in a predetermined power system that has a predetermined relationship with the power system where the accident occurred. A fault location calculation unit calculates the location of the fault based on the waveform obtained from the waveform input unit, Equipped with Accident point locating device.

2. The fault location calculation unit determines the location of the fault if the fault point cannot be identified by the sensors installed in the fault-causing power system alone, by comparing the waveform measured by the sensors installed in the fault-causing power system with the waveform measured by the sensors installed in the predetermined power system. The accident location device according to claim 1.

3. The accident location calculation unit detects the time when a predetermined physical phenomenon caused by the accident is detected by a sensor, based on the waveform obtained from the waveform input unit, and calculates the accident location based on the detected time. The accident location device according to claim 2.

4. The system further comprises a result output unit that outputs the calculation results of the accident location calculation unit. The accident location device according to claim 3.

5. The aforementioned predetermined power system is located within a predetermined range of the power system where the fault occurred. The accident location device according to claim 4.

6. The aforementioned predetermined power system is connected to the fault-affected power system via a normally open switchgear. The accident location device according to claim 4.

7. The transformer bank to which the aforementioned fault-stricken power system is connected is different from the transformer bank to which the aforementioned predetermined power system is connected. The accident location device according to claim 4.

8. The accident location calculation unit requests the sensors installed in the predetermined power system to transmit the measured waveforms to the accident location calculation unit. The accident location device according to claim 4.

9. The system further includes a storage unit that stores a management table for extracting power systems that have a predetermined relationship from among multiple power systems. The accident location device according to claim 4.

10. The fault location device according to claim 9, wherein the management table is updated in accordance with changes in the configuration including the plurality of power systems.

11. The fault location calculation unit determines the range in which the fault-causing power system exists based on the waveform measured by the sensor of the fault-causing power system. The accident location device according to claim 10.

12. The fault location calculation unit calculates the distance from either the sensor in the fault-causing power system or the sensor in the predetermined power system to the fault point, using the difference between the surge arrival time measured by a sensor in the fault-causing power system and the surge arrival time measured by a sensor in the predetermined power system, which is the predetermined physical phenomenon caused by the fault. The accident location device according to claim 3.

13. The accident location calculation unit, when there are multiple sensors installed in the predetermined power system, selects which sensor's measured waveform to use based on the shape, amplitude, and frequency band included in the waveform measured by the multiple sensors. The accident location device according to claim 4.

14. A method for locating a fault point in a power system using a fault point location device, A waveform input step in which a waveform measured by a sensor installed in the power system where the accident occurred and a waveform measured by a sensor installed in a predetermined power system that has a predetermined relationship with the power system where the accident occurred are input, A fault location calculation step calculates the location of the fault based on the waveform acquired in the waveform input step, Execute Accident point location method.

15. The fault location calculation step involves determining the location of the fault from the waveform measured by the sensor installed in the fault-causing power system and the waveform measured by the sensor installed in the predetermined power system, if the fault point cannot be identified by the sensor installed in the fault-causing power system alone. The accident location method according to claim 14.

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