JP2023142679A - system or method - Google Patents

Abstract

To provide a novel system or program for monitoring power lines.SOLUTION: A system having two or more meters for measuring inter-line voltages and phase currents of a power line is provided, the system comprising a control unit configured to perform processing for acquiring the inert-line voltages and, when a rate of reduction in an inter-line voltage stays at a threshold or higher for a set period or longer, short-circuit determination processing for determining occurrence of a short-circuit accident.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a system or method.

BACKGROUND ART A device is known that measures zero-phase voltage (V0) in a power transmission line and detects the occurrence of a ground fault (for example, Patent Document 1).

Japanese Patent Application Publication No. 2005-300205

In the past, only ground faults were located because covered wires were used in power distribution lines.

However, in the fault location system for power transmission lines, the power transmission lines use bare wires, and it is necessary to locate them when short circuits occur due to galloping between towers. However, when a short circuit occurs, V0 is not generated in the power transmission line, so a new detection method is required.

In consideration of the above-mentioned problems, one aspect of the present invention is a system including one or more measuring instruments that measure line voltage and phase current of a power transmission line, the process of acquiring the line voltage, and the process of acquiring the line voltage. To provide a system that executes short-circuit determination processing that determines that a short-circuit accident has occurred when a state in which the rate of decrease in line voltage exceeds a threshold continues for a set period or more.

Further, as one aspect of the present invention, for a system having two or more measuring instruments that measure line voltage and phase current of a power transmission line, the present invention provides a process for acquiring the line voltage, and a reduction rate of the line voltage. Provided is a program that executes a short-circuit determination process that determines that a short-circuit accident has occurred when a state in which the voltage exceeds a threshold continues for a set period or longer.

According to the present invention, a new system or program can be provided.

1 is a diagram showing the configuration of a failure point locating system according to an embodiment. It is a diagram showing the configuration of a power transmission line and a measuring instrument according to an embodiment. 1 is a diagram showing (a) a hardware configuration and (b) a functional configuration of a device according to an embodiment; FIG. This is an example of a current waveform created based on the line voltage time history acquired or stored by the device. It is a short circuit detection flow in an embodiment. It is a ground fault detection flow in an embodiment. This is a flowchart showing details of accident detection processing.

<Embodiment>
(overview)
A monitoring system 1, which is one embodiment of the present invention, will be described with reference to FIGS. 1 to 7.

As shown in FIGS. 1 and 2, the monitoring system 1 is a system that monitors a power transmission line 2 that transmits three-phase AC power. The monitoring system 1 includes measuring instruments 10 and 11, a device 20, and a network 5. The device 20 and the measuring instruments 10 and 11 are communicably connected via the network 5.

The network 5 is a wireless or wired communication means, such as the Internet, a WAN (Wide Area Network), a LAN (Local Area Network), a public communication network, or a dedicated line. Note that although the monitoring system 1 according to this embodiment is configured by the plurality of information management devices described above, the present invention does not limit the number of these devices. Therefore, the monitoring system 1 can be configured by one or more devices as long as they have the following functions.

Measuring instruments 10 and 11 are installed in the premises of the transmission end substation and the receiving end substation of the transmission line 2, respectively, and measure the zero-sequence voltage of the transmission line 2 and the line voltage between each phase of U, V, and W. It has a measurement function (Figures 1 and 2). The measuring instruments 10 and 11 have a function of transmitting the measured line voltage, zero-sequence voltage, phase current, and zero-sequence current to the device 20 via the network 5. The measuring instruments 10 and 11 communicate with GPS satellites, receive GPS time signal times at regular intervals, and synchronize the times used by each measuring instrument.

The device 20 acquires the line voltage (between each phase between UV, V-W, and W-U) of the power transmission line 2 from the measuring instruments 10 and 11, the zero-sequence voltage, the phase current, and the zero-sequence current, This is a device that monitors the power transmission line 2 from a remote location to see if there is any abnormality.

FIG. 3A shows an example of hardware (referred to as a processing device 100) used to realize the measuring instruments 10 and 11 and the device 20. As shown in the figure, the processing device 100 includes a processor 101, a main storage device 102, an auxiliary storage device 103, an input device 104, an output device 105, and a communication device 106. These are communicably connected to each other via a communication means such as a bus (not shown).

The processor 101 is configured using a CPU (Central Processing Unit), an MPU (Micro Processing Unit), and the like. The functions of the processing device 100 are realized by the processor 101 reading and executing programs stored in the main storage device 102.

The main storage device 102 is a device that stores programs and data, and is a ROM (Read Only Memory), a RAM (Random Access Memory), a nonvolatile semiconductor memory (NVRAM (Non Volatile RAM)), or the like. The auxiliary storage device 103 includes various types of non-volatile memory (NVRAM) such as SSD (Solid State Drive), SD memory card, hard disk drive, optical storage device (CD (Compact Disc), and DVD (Digital Versatile Disc). ), storage area of cloud server, etc.

The input device 104 is an interface that accepts input of information, and is, for example, a keyboard, a mouse, a touch panel, a card reader, a voice input device (such as a microphone), a voice recognition device, or the like. The processing device 100 may be configured to receive information input from other devices via the communication device 106.

The output device 105 is an interface that outputs various information, and includes, for example, a screen display device (liquid crystal monitor, LCD (Liquid Crystal Display), graphic card, etc.), printing device, etc.), an audio output device (speaker, etc.), an audio output device, etc. Such as synthesis equipment. A configuration may also be adopted in which the processing device 100 outputs information to and from another device via the communication device 106.

The communication device 106 is a wired or wireless communication interface that realizes communication with other devices via the network 5, and includes, for example, a NIC (Network Interface Card), a wireless communication module, and a USB (Universal Serial Interface). ) module, serial communication module, etc.

[Functional configuration]
The main functional configuration of the processing device 100 is shown in FIG. 3(b). As shown in the figure, the device 20 includes a storage area 114 and a management section 120.

The storage area 114 is formed in the main storage device 102 or the auxiliary storage device 103. In the storage area 114, the time history of the acquired line voltage and zero-sequence voltage is stored for each of the measuring instruments 10 and 11.

The functions of the management unit 120 are realized by the processor 101 reading and executing programs stored in the main storage device 102 or the auxiliary storage device 103. The management unit 120 performs processing such as analysis of line voltage, zero-sequence voltage, phase current, and zero-sequence current. Details will be described later.

〔process〕
An example of processing executed in the monitoring system 1 will be described below using flowcharts shown in FIGS. 5 to 7.

First, in each of the measuring instruments 10 and 11 and the device 20, a program stored in the main storage device 102 or the auxiliary storage device 103 is activated by the processor 101, and the processing of the monitoring system 1 is executed as follows.

The processes executed in the monitoring system 1 can be roughly divided into two types: a short circuit detection flow (FIGS. 5 and 7) and a ground fault detection flow (FIGS. 6 and 7).

(Short circuit detection flow)
In the short circuit detection flow (FIG. 5), the measuring instruments 10 and 11 acquire the line voltage of the power transmission line 2, and check whether the line voltage has decreased by a set percentage for a set period (S1). Here, the set ratio and the set period are preset values. The line voltage (and zero-sequence voltage described below) is acquired at an arbitrary sampling rate, and the rate is set, for example, in a range of 10 kHz or more and 1000 kHz (kilohertz) or less.

For example, if the line voltage between UV, V-W, or W-U continues to decrease by a set percentage (for example, 10%, etc.) for a preset number of cycles, the measuring instrument 10, 11, the process advances to S2 (S1: YES). If the condition in S1 is not satisfied (S1: NO), the measuring instruments 10 and 11 continue the process in step S1.

In step S2, the measuring instruments 10 and 11 perform fault detection processing and save the surge waveform of the phase current up to the point in time when a drop in line voltage is recognized in their own storage area 114. Details of the accident detection process in step S2 will be described later.

Furthermore, the measuring instruments 10 and 11 check whether an overcurrent has been detected (S4). If an overcurrent is detected (S4: YES), a call is made to notify the user of the occurrence of a short circuit accident using the output device 105, communication device 106, etc. (S5). Further, if no overcurrent is detected, the occurrence of an accident is not called (S6). After that, the device 20 continues post-processing such as power outage determination.

(Ground fault detection flow)
The measuring instruments 10, 11 and the device 20 also perform ground fault detection processing independently of short circuit accident detection (FIG. 6). In the ground fault detection process, the level detection processes of S8, S10, S12, and S2 and the ground fault determination processes of S13 to S18 are executed in parallel.

The measuring instruments 10 and 11 cancel the residual voltage for level detection in the measuring instruments 10 and 11 in step S8, obtain the amount of change in the zero-sequence voltage for each cycle, and perform the processing from step S10 onwards.

In step 10, the measuring instruments 10 and 11 acquire the amount of change in the zero-sequence voltage, and further check whether the amount of change in the zero-sequence voltage is equal to or higher than the set ratio (for example, 50%) of the setting V0 (S10), and whether the state is It is confirmed whether the process has continued for a set time or longer (S12). Note that the setting V0 is a preset value.

If the conditions of steps S10 and S12 are both satisfied (S10: YES and S12: YES), the accident detection process (S2) is executed. In step S2, the measuring instruments 10 and 11 save the surge current waveform of the zero-sequence current up to the time when a change in the set zero-sequence voltage is recognized (that is, the time when the conditions in steps S10 and S12 are satisfied). do.

If either step S10 or S12 is not satisfied (S10: NO or S12: NO), the measuring instruments 10, 11 return the process to S8.

On the other hand, in the ground fault determination process (right side of FIG. 6), the measuring instruments 10 and 11 cancel the residual voltage for fault determination in the measuring instruments 10 and 11 in step S13, and obtain the amount of change in the zero-sequence voltage for each cycle. Then, the process from step S15 onwards is performed.

The measuring instruments 10 and 11 check whether the measured zero-sequence voltage is equal to or higher than the set V0 (S15) and whether this state continues for the set number of cycles or more (S17).

If the conditions in steps S15 and S17 are both satisfied (S15: YES and S17: YES), the measuring instruments 10 and 11 determine that a ground fault has been determined (S18).

On the other hand, if either step S15 or S17 is not satisfied (S15: NO or S17: NO), the measuring instruments 10 and 11 return the process to S13.

Step S19 is a process for determining whether notification or some other measure is necessary when a ground fault occurs. When the process reaches step S19 through both S2 and S18, the measuring instruments 10 and 11 notify that an accident has been detected using the output device 105, the communication device 106, etc. (S19). Thereafter, the device 20 performs post-processing such as power outage determination.

Note that if the process does not reach step S19 through both S2 and S18 even after a certain period of time has elapsed, the monitoring system 1 returns the process to step S8.

In FIG. 7, the measuring instruments 10 and 11 show a flowchart for determining whether the accident detection process has occurred through short circuit detection or ground fault detection (S21).

In the case of short circuit detection (S21: short circuit), the measuring instruments 10 and 11 apply a low pass filter (LPF) to the acquired surge current waveform of the phase current, and save the result of the filter processing in their own storage area 114, It is transmitted to the device 20 (S22). In step S22, the LPF reduces or cuts the time history waveform having a frequency equal to or higher than the first predetermined value. The first predetermined value is set in advance within a range of 1 MHz or more and less than 10 MHz (megahertz). Note that communication between the measuring instruments 10 and 11 and the device 20 is performed by packet communication.

When the accident detection process occurs due to ground fault detection (S21: ground fault), the measuring instruments 10 and 11 apply LPF to the acquired surge current waveform of the zero-sequence current and save it in their own storage area 114, It is transmitted to the device 20 (S23). In step S23, the LPF reduces or cuts the time history waveform having a frequency equal to or higher than a second predetermined value. The second predetermined value is set in advance within a range of 10 kHz or more and less than 1 MHz.

In step S24, the device 20 uses the LPF-processed surge current waveforms received from the measuring instruments 10 and 11 to calculate the point where the accident occurred based on these time histories.

To be more specific, as shown in FIG. 4, the device 20 determines the time when the surge current waveform was measured, that is, the time when the surge current being measured suddenly changed, for each of the measuring instruments 10 and 11 due to a short circuit or ground fault. It is measured as the time of occurrence. Next, the device 20 determines at which point on the power transmission line 2 there is a short circuit or ground fault, based on the occurrence time of the short circuit or ground fault acquired by each measuring device 10, 11 and the position of each measuring device 10, 11. Calculate whether an accident has occurred.

Next, the device 20 notifies the user of the calculated occurrence point of the short circuit accident or ground fault accident by displaying it on the output device 105 or the like (S25).

<Modified example>
In the embodiment, the monitoring system 1 includes two measuring instruments 10 and 11, but the number of measuring instruments is arbitrary as long as it is two or more. Therefore, the monitoring system 1 may be configured to include three or more measuring instruments. Further, the device 20 and the measuring instruments 10 and 11 may be integrated. The device 20 may perform part or all of the processing performed by the measuring instruments 10 and 11. Further, the measuring instruments 10 and 11 may execute part or all of the processing executed by the device 20.

<Effect>
In the embodiment and modified examples, the monitoring system 1 includes two or more measuring instruments 10 and 11 that measure the line voltage and phase current of the power transmission line 2. The monitoring system 1 acquires the line voltage, and executes a short circuit judgment process (S1) in which it is determined that a short circuit accident has occurred if the line voltage drop rate continues to be equal to or higher than a threshold value for a set period or more. do.

The above configuration utilizes the fact that the line voltage decreases when a short circuit occurs in the power transmission line 2. A short circuit accident can be detected by performing the above process of detecting a drop in line voltage.

When the monitoring system 1 determines that a short-circuit accident has occurred in the short-circuit determination process (S1), the monitoring system 1 further performs a process (S2) in which the surge waveform of the phase current up to the time when it is determined that the short-circuit accident has occurred is stored in the storage unit. Execute.

With the above configuration, the amount of data stored in the storage unit can be reduced by not storing the surge waveform of the phase current after the time when it is determined that a short-circuit accident has occurred. Therefore, the capacity of the storage section can be saved, and the sampling rate when acquiring the phase current surge waveform can be set to several tens of MHz. For example, the length of the phase current surge waveform to be stored may be 1 millisecond or less. Processing such as analysis of saved data can be performed quickly.

The monitoring system 1 performs filter processing (S22) to reduce frequency components of a first predetermined value or higher in the surge waveform of the phase current, and determines the time at which the occurrence of a short circuit accident is measured based on the surge waveform of the phase current after the filter processing. The process (S24) is further executed. This first predetermined value is set in a range of 1 MHz or more and less than 10 MHz.

In the above configuration, noise can be removed by the LPF. Therefore, the measurement time of the phase current surge waveform can be accurately acquired.

The monitoring system 1 uses the surge waveforms of the phase currents acquired from each of the measuring instruments 10 and 11 to execute a process (S24) of calculating the point where the short circuit accident has occurred.

With the above configuration, it is possible to accurately measure the point where a short circuit has occurred using the surge waveform of the phase current of the short circuit at two measurement points. In particular, since the time history from which high frequency noise has been removed by the LPF is used, it is possible to determine the exact time and exact point of occurrence.

The monitoring system 1 executes a process of detecting an overcurrent in the line voltage time history (S4), and a process of notifying the occurrence of a short circuit accident when an overcurrent is detected (S4: YES) (S5). .

The above configuration utilizes the fact that when a short circuit occurs, a large overcurrent flows on the power supply side from the short circuit location. By using overcurrent detection, it is possible to accurately determine the occurrence of a short circuit accident. In particular, when used together with the determination based on the drop in line voltage (S1), the possibility of false detection of noise and false alarms due to planned power outages can be eliminated with high probability.

The monitoring system 1 measures the zero-sequence voltage of the power transmission line 2 . In addition, the monitoring system 1 performs a process of acquiring the zero-sequence voltage (S10) and a ground fault judgment that determines that a ground fault has occurred if the state in which the zero-sequence voltage is equal to or higher than a set value continues for a set time or longer. Processes (S10, S12) are executed.

The above configuration utilizes the fact that the zero-sequence voltage increases when a ground fault occurs in the power transmission line 2. By performing the above processing, a change in zero-sequence voltage can be detected, and a ground fault can be detected.

When the monitoring system 1 determines that a ground fault has occurred in the ground fault determination process (S10: YES and S12: YES), the monitoring system 1 saves the surge waveform of the zero-sequence current up to the time when it is determined that a ground fault has occurred. The process (S2) is executed.

With the above configuration, the amount of data stored in the storage unit can be reduced by storing the surge waveform of the zero-sequence current up to the time when it is determined that a ground fault has occurred. Therefore, the capacity of the storage section can be saved, and the sampling rate when acquiring the zero-sequence current surge waveform can be increased to several tens of MHz. For example, the length of the surge waveform of the zero-sequence current to be stored can be set to 1 millisecond or less, as shown in FIG. In addition, processing such as analysis of saved data can be performed quickly.

The monitoring system 1 performs filter processing (S23) to reduce frequency components equal to or higher than a second predetermined value in the surge waveform of the zero-sequence current, and measures the occurrence of a ground fault based on the surge waveform of the zero-sequence current after the filter processing. A process of measuring the time as the ground fault measurement time (S24) is further executed. Here, the second predetermined value is set in a range of 10 kilohertz or more and less than 1 megahertz.

In the above configuration, noise can be removed by the LPF. Therefore, the point of change in the surge current waveform (surge arrival time) can be accurately measured.

The monitoring system 1 executes a process of calculating the point where the ground fault accident occurred from the ground fault measurement time measured by each of the measuring instruments 10 and 11 (S24).

With the above configuration, it is possible to accurately measure the point where the ground fault occurs based on the measurement times of the ground fault at the two measurement points. In particular, since the surge waveform of the zero-sequence current from which high-frequency noise has been removed by the LPF is used, it is possible to accurately determine the time when the ground fault occurs and the exact point where the ground fault occurs.

The monitoring system 1 performs a ground fault determination process (S15 to S18) in which it is determined that a ground fault has occurred if the state in which the zero-phase voltage is equal to or higher than the set voltage continues for a predetermined period or longer (S15: YES and S17: YES). , equivalent to additional processing). Furthermore, if it is determined that a ground fault has occurred in both level detection (an example of ground fault determination processing) and ground fault determination, a process (S19) for notifying the occurrence of a ground fault is executed.

In the above configuration, by adding the additional process (S18), it is possible to accurately determine whether a ground fault has occurred. In particular, when used together with the determination based on the rise in zero-sequence voltage (S2, S10, S12), the possibility of false alarms due to false noise detection can be eliminated with a high probability. Additionally, it is possible to screen out conditions that do not need to be notified, such as slight ground faults.

Surveillance system 1
power transmission line 2
Measuring instruments 10, 11
device 20

Claims (11)

A system comprising two or more measuring instruments for measuring line voltage and phase current of a power transmission line,
obtain the line voltage;
A system that executes short-circuit determination processing that determines that a short-circuit accident has occurred when a state in which the rate of decrease in line voltage is equal to or greater than a threshold continues for a set period or more. If it is determined that a short circuit accident has occurred in the short circuit determination process,
The system according to claim 1, further executing processing for storing a surge current waveform of a phase current up to a point in time when it is determined that a short-circuit accident has occurred. a first filter process that reduces frequency components equal to or higher than a first predetermined value in the surge waveform of the phase current;
further performing a process of measuring a time when the occurrence of a short circuit accident is measured as a short circuit measurement time based on the surge waveform of the phase current after the first filter processing;
The system according to claim 2, wherein the first predetermined value is set in a range of 1 MHz or more and less than 10 MHz. The one or more measuring instruments include a first measuring instrument and a second measuring instrument,
4. The system according to claim 3, further executing processing for calculating a point where a short circuit accident occurs using surge waveforms of the phase current measured by each of the first measuring device and the second measuring device. a process of detecting overcurrent in the line voltage time history;
The system according to claim 3 or 4, further executing a process of notifying the occurrence of a short circuit accident when the overcurrent is detected. The one or more measuring devices further measure a zero-sequence voltage of the power transmission line,
a process of acquiring the zero-sequence voltage;
6. A ground fault determination process for determining that a ground fault has occurred if the zero-sequence voltage remains at or above a set value for a set time or more is further executed. system described in. If it is determined that a ground fault accident has occurred in the ground fault judgment process,
7. The system according to claim 6, further executing processing for storing a surge waveform of zero-sequence current up to the point in time when it is determined that a ground fault has occurred. a second filter process that reduces frequency components equal to or higher than a second predetermined value in the surge waveform of the zero-sequence current;
further performing a process of measuring a time when the occurrence of a ground fault accident is measured as a ground fault measurement time based on the surge waveform of the zero-sequence current after the second filter processing;
The system according to claim 7, wherein the second predetermined value is set in a range of 10 kilohertz or more and less than 1 megahertz. The one or more measuring instruments include a first measuring instrument and a second measuring instrument,
The system according to claim 7 or 8, further executing a process of calculating a point where a ground fault accident occurs from the ground fault measurement time measured by each of the first measuring device and the second measuring device. additional processing for determining that a ground fault has occurred if the zero-sequence voltage remains at or above a set voltage for a predetermined period or more;
If it is determined that a ground fault accident has occurred in both the ground fault determination process and the additional process, the system further executes a process of notifying the occurrence of a ground fault. system. For systems equipped with two or more measuring instruments that measure the line voltage of power transmission lines,
a process of acquiring the line voltage;
A program that executes short-circuit determination processing that determines that a short-circuit accident has occurred when a state in which the rate of decrease in line voltage is equal to or greater than a threshold continues for a set period or more.

Images