Automatic remote monitoring system for power receiving and transforming equipment

Abstract

This invention provides an automated remote monitoring system for power receiving and transforming equipment that can determine whether a minor ground fault in a high-voltage circuit is located on the load side or the power supply side due to insulation degradation. [Solution] The automatic remote monitoring system 1 for power receiving and transforming equipment includes multiple sensors that measure the state of the power receiving and transforming equipment 14, which is connected to a PAS 13 located at the responsibility demarcation point of the high-voltage circuit 10 that supplies electricity from a power source 11 to a load 12 via a service drop cable 15 that constitutes part of the high-voltage circuit 10, or the insulation state of the high-voltage circuit 10; at least one measurement and monitoring device 4#1 to which the multiple sensors are connected; and a remote monitoring center 5 that remotely monitors the measurement data from the measurement and monitoring device 4#1. In the case of the high-voltage circuit, it determines whether or not a minor ground fault has occurred on the load 12 side of the direction determination point.

Description

Technical Field

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[0001] The present invention relates to an automatic remote monitoring system for substation and transmission equipment, and particularly to an automatic remote monitoring system for substation and transmission equipment that determines whether the ground fault point is inside or outside the substation in a high-voltage circuit.

Background Art

[0002] This technology captures the ground fault current as a precursor phenomenon of an accident when a micro ground fault occurs and discriminates the direction, thereby supplementing the regular inspection of power equipment and leading to an improvement in reliability. Usually, high-voltage or extra-high-voltage substation and transmission equipment is obliged to undergo regular maintenance inspections according to the Electricity Business Act. Various electrical equipment such as power cables, lightning arresters, power transformers, synchronous condensers, instrument transformers, current transformers, etc. are connected to the substation and transmission equipment. Due to insulation deterioration in these various electrical equipment, a ground fault accident accompanied by a power outage of the in-station equipment may occur.

[0003] In the monitoring of this insulation deterioration state, the load side end of the incoming cable drawn from the responsibility demarcation point, which is the connection point with the high-voltage circuit (hereinafter also referred to as the "direction discrimination point"), is called the inside of the substation for the load side, and the power source side from the direction discrimination point is called the outside of the substation.

[0004] As insulation deterioration progresses due to aging of equipment, etc., the ground fault current tends to gradually increase. Therefore, an automatic security inspection system that discovers micro ground faults, which are precursors of ground fault accidents, by constantly monitoring the ground fault current flowing into the in-station high-voltage circuit is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the method disclosed in Patent Document 1 had the problem that it was not possible to determine whether the location where a minor ground fault occurred and insulation degradation occurred was on the load side or the power supply side.

[0007] The present invention has been made to solve the above-mentioned conventional problems, and aims to provide an automatic remote monitoring system for power receiving and transforming equipment that can determine whether the location of insulation degradation where a minor ground fault has occurred in a high-voltage circuit is on the load side or the power supply side. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides an automatic remote monitoring system for power receiving and transforming equipment comprising: a plurality of sensors that measure the state of power receiving and transforming equipment connected to a high-voltage air switch installed at the responsibility demarcation point of a high-voltage circuit, which is a three-phase AC circuit that supplies electricity from a power source to a load, via a service drop cable that constitutes a part of the high-voltage circuit, or the insulation state of the high-voltage circuit; at least one measurement and monitoring device to which the plurality of sensors are connected; and a remote monitoring center that remotely monitors the measurement data from at least one of the measurement and monitoring devices. The system comprises at least one measurement and monitoring device which detachably mounts a measurement module and a communication module, each measurement and monitoring device which is connectable to a function module via a communication I / F, and the plurality of sensors which include a first zero-phase current transformer attached to the incoming cable for detecting the first zero-phase current flowing through the incoming cable, and a second zero-phase current transformer attached to a grounded shield wire drawn out from the end of the incoming cable on the power receiving and transforming equipment side, with the polarity of the ground point side being the same as the polarity of the power supply side of the first zero-phase current transformer, The measurement module includes: a comparison waveform acquisition unit that acquires the waveform of the first zero-sequence current detected by the first zero-sequence current transformer as a comparison waveform; a comparison waveform zero-cross detection unit that detects the zero-cross point of the comparison waveform; a reference waveform acquisition unit that acquires the waveform of the second zero-sequence current detected by the second zero-sequence current transformer as a reference waveform; a reference waveform zero-cross detection unit that detects the zero-cross point of the reference waveform; and a time difference calculation unit that calculates the time difference of the zero-cross point of the comparison waveform with respect to the time of the zero-cross point of the reference waveform. The communication module includes a phase difference calculation unit that converts the time difference calculated by the difference calculation unit into a phase difference of the comparison waveform with respect to the phase of the reference waveform, and a ground fault direction determination unit that determines that a minor ground fault has occurred on the load side of the end of the incoming cable on the substation side when the phase difference calculated by the phase difference calculation unit is within a phase difference range in which the polarity of the first zero-sequence current and the second zero-sequence current are the same. The communication module is configured to transmit the determination result from the ground fault direction determination unit and the monitoring result from the function module to the remote monitoring center.

[0009] With this configuration, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention can determine whether the location of the insulation degradation where a minor ground fault has occurred is on the load side or the power supply side by calculating the phase difference between the first zero-sequence current and the second zero-sequence current based on the zero-crossing point of the first zero-sequence current detected by the first zero-sequence current transformer and the zero-crossing point of the second zero-sequence current detected by the second zero-sequence current transformer. Furthermore, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention can remotely monitor the acquired ground fault direction determination result at a remote monitoring center.

[0010] Furthermore, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention may be configured in which the measurement module is detachably mounted.

[0011] With this configuration, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention can, for example, distribute and connect multiple sensors to two or more measurement modules when the measurement monitoring device has detachable measurement modules. As a result, even if a measurement module of one of the measurement monitoring devices fails, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention can transmit measurement data and alarm signals from the measurement modules of other measurement monitoring devices to the remote monitoring center, minimizing the damage caused by data loss.

[0012] Furthermore, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention further includes, in the measurement module, a high-voltage leakage current effective value calculation unit that calculates the effective value of the comparison waveform at intervals defined by the interval of zero-crossing points detected by the comparison waveform zero-crossing detection unit; a high-voltage leakage current average value calculation unit that calculates an average value obtained by averaging the effective value of the comparison waveform calculated by the high-voltage leakage current effective value calculation unit over multiple periods; and a high-voltage leakage current alarm necessity determination unit that determines whether the average value calculated by the high-voltage leakage current average value calculation unit exceeds a predetermined high-voltage leakage current threshold, and issues a high-voltage leakage current alarm signal if the average value calculated by the high-voltage leakage current average value calculation unit exceeds the high-voltage leakage current threshold; and the communication module may be configured to transmit the high-voltage leakage current alarm signal, the effective value of the comparison waveform calculated by the high-voltage leakage current effective value calculation unit, and the average value calculated by the high-voltage leakage current average value calculation unit to the remote monitoring center.

[0013] With this configuration, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention can acquire data on high-voltage leakage current in the high-voltage circuit based on the first zero-phase current detected by the first zero-phase current transformer. Furthermore, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention can remotely monitor the acquired high-voltage leakage current data and the high-voltage leakage current alarm signal that is issued when there is an abnormality in the acquired high-voltage leakage current data at a remote monitoring center.

[0014] Furthermore, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention further includes current sensors for measuring power receiving current attached to the secondary side of a current transformer installed in the high-voltage circuit, and the measurement module includes a power receiving current waveform acquisition unit that acquires the waveform of the power receiving current detected by the power receiving current measuring current sensor as a power receiving current waveform, a power receiving current zero-cross detection unit that detects the zero-cross point of the power receiving current waveform, a power receiving current RMS value calculation unit that calculates the RMS value of the power receiving current waveform at intervals defined by the interval of the zero-cross point detected by the power receiving current zero-cross detection unit, and the power receiving current RMS value calculation unit The communication module further includes: a power receiving current average value calculation unit that calculates an average value obtained by averaging the effective value of the power receiving current waveform over multiple periods; and a power receiving current alarm necessity determination unit that determines whether the average value calculated by the power receiving current average value calculation unit exceeds a predetermined power receiving current threshold, and issues a power receiving current alarm signal if the average value calculated by the power receiving current average value calculation unit exceeds the power receiving current threshold. The communication module may be configured to transmit the power receiving current alarm signal, the effective value of the power receiving current waveform calculated by the power receiving current effective value calculation unit, and the average value calculated by the power receiving current average value calculation unit to the remote monitoring center.

[0015] With this configuration, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention can acquire data on the power receiving current in the high-voltage circuit based on the power receiving current detected by the current sensor. Furthermore, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention can remotely monitor the acquired power receiving current data and the power receiving current alarm signal that is issued when there is an abnormality in the acquired power receiving current data at a remote monitoring center.

[0016] Furthermore, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention further includes, in the measurement module, a waveform extraction unit that extracts the power receiving current waveform for one cycle defined by the interval of zero-crossing points detected by the power receiving current zero-crossing detection unit; a Fourier transform calculation unit that performs a Fourier transform on the power receiving current waveform for one cycle extracted by the waveform extraction unit to calculate the fundamental wave component and a plurality of harmonic components of the power receiving current waveform; a total distortion rate calculation unit that calculates a total distortion rate which is the ratio of the sum of the plurality of harmonic components to the fundamental wave component; and a total distortion rate alarm necessity determination unit that determines whether the total distortion rate calculated by the total distortion rate calculation unit exceeds a predetermined total distortion rate threshold, and issues a total distortion rate alarm signal if the total distortion rate calculated by the total distortion rate calculation unit exceeds the total distortion rate threshold, and the communication module may be configured to transmit the total distortion rate alarm signal and the total distortion rate calculated by the total distortion rate calculation unit to the remote monitoring center.

[0017] With this configuration, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention can acquire data on the total distortion rate of the received current detected by the current sensor. Furthermore, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention can remotely monitor the acquired total distortion rate data and the total distortion rate alarm signal that is issued when an abnormality is detected in the acquired total distortion rate data at a remote monitoring center.

[0018] Furthermore, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention may be configured such that the remote monitoring center has a display device that displays at least a portion of the information transmitted from the communication module to the remote monitoring center.

[0019] This configuration allows the automatic remote monitoring system for power receiving and transforming equipment according to the present invention to enable monitors at a remote monitoring center to access various measurement data and alarm signals in high-voltage circuits via a display device. As a result, the automatic remote monitoring system for power receiving and transforming equipment according to the present invention facilitates the establishment of a system for promptly conducting accident investigations and determining their causes, thereby improving electrical safety quality.

[0020] Further, the power receiving and transforming equipment automatic remote monitoring system according to the present invention may further include a browsing terminal connected to the remote monitoring center via the Internet, and the remote monitoring center may be configured to display at least a part of the information transmitted from the communication module to the remote monitoring center on the browsing terminal.

[0021] With this configuration, the power receiving and transforming equipment automatic remote monitoring system according to the present invention enables a consumer of the power receiving and transforming equipment to grasp various measurement data in the high-voltage circuit via the browsing terminal.

Advantages of the Invention

[0022] The present invention provides a power receiving and transforming equipment automatic remote monitoring system capable of determining whether a location with insulation deterioration where a minor ground fault has occurred in a high-voltage circuit is on the load side or the power supply side.

Brief Description of the Drawings

[0023] [Figure 1] It is a block diagram showing the configuration of a power receiving and transforming equipment automatic remote monitoring system according to an embodiment of the present invention. [Figure 2] It is a diagram showing an installation example of various sensors included in the power receiving and transforming equipment automatic remote monitoring system according to an embodiment of the present invention. [Figure 3] It is a block diagram showing the configuration of a measurement module included in the power receiving and transforming equipment automatic remote monitoring system according to an embodiment of the present invention. [Figure 4] (a) is a functional block diagram of a high-voltage leakage current calculation unit in the measurement module, and (b) is a functional block diagram of a power reception current calculation unit in the measurement module. [[ID=2用29]] [Figure 5] It is a diagram for explaining a method of calculating a high-voltage leakage current by a high-voltage leakage current calculation unit and a method of calculating a power reception current by a power reception current calculation unit. [Figure 6] It is a diagram for explaining a method of calculating a phase difference by a high-voltage leakage current calculation unit. [Figure 7] It is a diagram for explaining a method of calculating a total distortion rate by a power reception current calculation unit. [Figure 8] This diagram illustrates the leakage current in the low-voltage circuit on the secondary side of a transformer installed in a high-voltage circuit. [Figure 9] (a) and (b) are diagrams showing examples of displays in the display device of the remote monitoring center equipped with the automatic remote monitoring system for power receiving and transforming equipment according to an embodiment of the present invention. [Figure 10] This figure shows an example of a display in a display device at a remote monitoring center equipped with an automatic remote monitoring system for power receiving and transforming equipment according to an embodiment of the present invention. [Figure 11] Figures (a) to (c) show examples of displays on a viewing terminal provided in an automatic remote monitoring system for power receiving and transforming equipment according to an embodiment of the present invention. [Modes for carrying out the invention]

[0024] Hereinafter, an embodiment of the automatic remote monitoring system for power receiving and transforming equipment according to the present invention will be described with reference to the drawings.

[0025] First, the configuration of the automatic remote monitoring system for power receiving and transforming equipment according to an embodiment of the present invention will be described. As shown in Figure 1, the automatic remote monitoring system 1 for power receiving and transforming equipment of this embodiment comprises a measurement and monitoring device 4, such as at least one measurement and monitoring device 4#1 to which a plurality of sensors 3 installed in a high-voltage circuit 10 (see Figure 2) are connected, a remote monitoring center 5 that remotely monitors the measurement data from the measurement and monitoring device 4, and a viewing terminal 7 connected to the remote monitoring center 5 via the Internet 6.

[0026] The measurement and monitoring device 4 is configured to be daisy-chainable via RS-485 communication through the communication interface 40. Figure 1 shows an example configuration in which 15 measurement and monitoring devices 4#1 to 4#15 are daisy-chained. Note that the communication interface 40 of measurement and monitoring device 4#15 may be connected to the communication interface 40 of measurement and monitoring device 4#1 in a ring configuration. By using a ring configuration, communication interruption can be prevented even if one of the measurement and monitoring devices 4#1 to 4#15 fails or if a break occurs in the RS-485 connection cable.

[0027] The measurement and monitoring device 4 can have its functions expanded by detachably installing various optional modules inside. Furthermore, the measurement and monitoring device 4 may also have its functions expanded by connecting various functional modules 45 via a communication I / F 46. The functional modules 45 are configured to be daisy-chainable via RS-485 communication, and for example, up to 15 units can be daisy-chained.

[0028] The various functions of the functional module 45 include, for example, the functions of the measurement module 41 (described later), the functions of the pulse input module 42 (described later), a function to measure current, a function to measure temperature using a built-in temperature sensor, a function to measure the amount of power consumption reduction, and a function to measure power consumption. The measurement and monitoring device 4 can expand its functions to suit the environment of the power receiving and transforming equipment by appropriately connecting these functional modules 45 to the measurement and monitoring device 4.

[0029] Figure 1 shows an example in which a measurement module 41, a pulse input module 42, and a communication module 43 are detachably mounted on measurement monitoring device 4#1, and a measurement module 41 and two pulse input modules 42 are detachably mounted on measurement monitoring device 4#2. In this way, when at least two measurement monitoring devices 4 each detachably mount the measurement module 41, for example, multiple sensors 3 can be distributed and connected to two or more measurement modules 41.

[0030] The measurement module 41 is a module for monitoring the power receiving current, total distortion rate, high-voltage leakage current, etc., of the high-voltage circuit 10. The pulse input module 42 is a module for monitoring the measured values ​​of sensors that output pulse signals, among the multiple sensors 3 installed in the high-voltage circuit 10.

[0031] The communication module 43 is a module that transmits and receives measurement data and various alarm signals to and from the remote monitoring center 5 using an analog line or an LTE (Long Term Evolution) network. In addition, the communication module 43 is configured to transmit alarm signals to the remote monitoring center 5 using an analog line or an LTE network when an alarm signal is issued from any of the optional modules or functional modules 45.

[0032] Measurement and monitoring devices that do not have a communication module 43 installed, such as measurement and monitoring device 4#2, can send and receive measurement data and various alarm signals with the remote monitoring center 5 via a communication module 43 installed in another measurement and monitoring device.

[0033] As shown in Figure 2, a service drop cable 15, which constitutes part of the high-voltage circuit 10, is wired between a high-voltage air switch (PAS) 13, located at the responsibility demarcation point of the high-voltage circuit 10, which is a three-phase AC circuit supplying electricity from the power source 11 to the load 12, and the substation equipment 14, which is the customer's equipment. The service drop cable 15 is grounded by a three-phase shielded wire 16 that is drawn out from the end on the substation equipment 14 side.

[0034] The high-voltage circuit 10 is equipped with multiple sensors 3, such as a ZCT sensor 31 as a first zero-phase current transformer, a ZIV sensor 32 as a second zero-phase current transformer, a V0 sensor 33, a CT sensor 34, temperature sensors 35a, 35b, 35c, an ultrasonic sensor 36, a lightning sensor 37, a momentary voltage sag sensor 38, and power sensors 39a, 39b, 39c. These sensors are connected to a measurement module 41, a pulse input module 42, or a function module 45 to measure and monitor the insulation state of the high-voltage circuit 10 and the state of the power receiving and transforming equipment 14.

[0035] As shown in Figure 3, the symbols K and L in the ZCT sensor 31 and ZIV sensor 32 indicate the polarity of the zero-sequence current transformer. In each sensor, a positive current is detected when a zero-sequence current flows from polarity K to polarity L, and a negative current is detected when a zero-sequence current flows from polarity L to polarity K. Here, the ZCT sensor 31 is attached to the incoming cable 15 with polarity K on the power supply 11 side, and the ZIV sensor 32 is attached to the shielded wire 16 with polarity K on the ground point 25 side.

[0036] The ZCT sensor 31 is a sensor for measuring and monitoring high-voltage leakage current in the high-voltage circuit 10. It is used with the polarity K side end connected to terminal ZA-K of the measurement module 41 and the polarity L side end connected to terminal ZA-L of the measurement module 41. In addition, a load resistor 31a, for example, 100Ω, is connected between the polarity K side wiring and the polarity L side wiring of the ZCT sensor 31 to convert current to voltage.

[0037] The ZCT sensor 31 is a through-type zero-phase current transformer, such as a clamp-type zero-phase current transformer, and is attached to the incoming cable 15. When the ZCT sensor 31 is a clamp-type zero-phase current transformer, it has an annular detection section that can be opened. The incoming cable 15 is passed through the open detection section, and then the detection section is closed, so that the incoming cable 15 is inserted into the detection section. For example, the current measurement range of the ZCT sensor 31 is 50mA to 1250mA, and the size of the through-hole is 80 x 74mm.

[0038] The ZIV sensor 32 is a current sensor that detects a reference waveform for determining the direction of high-voltage leakage current in the high-voltage circuit 10. It is used with the polarity K side end connected to terminal ZB-K of the measurement module 41 and the polarity L side end connected to terminal ZB-L of the measurement module 41.

[0039] The ZIV sensor 32 is, for example, a through-type zero-phase current transformer and is attached to the shielded wire 16. The ZIV sensor 32 has an annular detection section and is used with the shielded wire 16 inserted through the detection section. For example, the current measurement range of the ZIV sensor 32 is 10mA or more, and the diameter of the through-hole is 24mm.

[0040] As shown in Figure 2, the V0 sensor 33 is a voltage sensor used to measure and monitor the tertiary voltage of an Earthed Voltage Transformer (EVT) when an EVT is installed in the high-voltage circuit 10, i.e., the ground fault voltage, and is used when connected to the measurement module 41. The V0 sensor 33 is configured to emit an alarm signal when the detected ground fault voltage exceeds a set value. The measurement module 41 transmits the ground fault voltage detected by the V0 sensor 33 and the alarm signal emitted when the ground fault voltage exceeds the set value via the communication module 43 to the remote monitoring center 5.

[0041] As shown in Figure 3, the CT sensor 34 is attached to the secondary side of the current transformer (CT) 17 installed in the high-voltage circuit 10 and constitutes a current sensor for measuring the received current and monitoring the received current and total distortion rate in the high-voltage circuit 10. The CT sensor 34 is used with the polarity K side end connected to terminal ZC-K of the measurement module 41 and the polarity L side end connected to terminal ZC-L of the measurement module 41. For example, the current measurement range of the CT sensor 34 is 1A to 30A, and the diameter of the through-hole is 24mm.

[0042] As shown in Figure 2, temperature sensors 35a to 35c are sensors for monitoring the exterior temperature of equipment such as static capacitors (SC) 18 and transformers (Tr) 19a and 19b installed in the high-voltage circuit 10, and are used when connected to the measurement module 41 or pulse input module 42. Temperature sensors 35a to 35c are configured to emit an alarm signal when the detected temperature exceeds a set value. The measurement module 41 or pulse input module 42 transmits the temperature measurement data detected by temperature sensors 35a to 35c and the alarm signal emitted when the detected temperature exceeds the set value via the communication module 43 to the remote monitoring center 5.

[0043] The ultrasonic sensor 36 is a sensor for detecting partial discharges that occur due to insulation failures in high-voltage electrical equipment such as the incoming cable 15 and the vacuum circuit breaker (VCB) 20, and is used when connected to the measurement module 41 or the pulse input module 42. When the ultrasonic sensor 36 detects a partial discharge, it emits an alarm signal indicating that a partial discharge has occurred. The measurement module 41 or the pulse input module 42 transmits the measurement data of the number of partial discharges detected by the ultrasonic sensor 36 and the alarm signal emitted when a partial discharge is detected by the ultrasonic sensor 36 to the remote monitoring center 5 via the communication module 43.

[0044] The lightning sensor 37 is a sensor that monitors the current flowing through the ground wire of the lightning arrester (LA) 21 and detects lightning surge intrusion (impact discharge current). It is used when connected to the measurement module 41 or the pulse input module 42. The measurement module 41 or the pulse input module 42 transmits an alarm signal, which is triggered when the current detected by the lightning sensor 37 exceeds a set value, to the remote monitoring center 5 via the communication module 43.

[0045] The voltage drop sensor 38 is a sensor for monitoring voltage drops in the high-voltage circuit 10 and is used when connected to the measurement module 41 or the pulse input module 42. The measurement module 41 or the pulse input module 42 transmits an alarm signal, which is triggered when the voltage detected by the voltage drop sensor 38 falls below a set value, to the remote monitoring center 5 via the communication module 43.

[0046] The power sensors 39a to 39c are used to monitor the power consumption of equipment such as the voltage transformer (VT) 22, CT 17, and Tr 19a, 19b installed in the high-voltage circuit 10, and are used when connected to the measurement module 41 or the pulse input module 42. The measurement module 41 or the pulse input module 42 transmits the power measurement data detected by the power sensors 39a to 39c to the remote monitoring center 5 via the communication module 43.

[0047] The configuration and operation of the measurement module 41 will be described below.

[0048] As shown in Figure 3, the measurement module 41 includes terminals ZA-K and ZA-L to which the ZCT sensor 31 is connected, an amplification circuit 410a, a filter circuit 411a for removing harmonic noise from the output of the amplification circuit 410a, and an ADC 412a for analog / digital conversion of the output of the filter circuit 411a at a predetermined sampling period. Here, the first zero-sequence current output from the ZCT sensor 31 is converted to a first zero-sequence voltage by the load resistor 31a and input to terminals ZA-K and ZA-L.

[0049] The amplification circuit 410a is configured to amplify the first zero-sequence voltage input from terminals ZA-K and ZA-L via the isolation transformer 413. The impedance of the isolation transformer 413 is, for example, 10 kΩ. The sampling rate of the ADC 412a is, for example, 128, when one cycle is 1 / 50 [Hz] or 1 / 60 [Hz].

[0050] The load resistor 31a, isolation transformer 413, amplification circuit 410a, filter circuit 411a, and ADC 412a constitute a comparison waveform acquisition unit that acquires the waveform of the first zero-sequence current flowing through the incoming cable 15, detected by the ZCT sensor 31, as comparison waveform data.

[0051] The measurement module 41 also includes terminals ZB-K and ZB-L to which the ZIV sensor 32 is connected, an amplification circuit 410b, a filter circuit 411b for removing harmonic noise from the output of the amplification circuit 410b, and an ADC 412b for analog / digital conversion of the output of the filter circuit 411b at a predetermined sampling period. Here, a load resistor 414, for example 2.2kΩ, is connected between terminals ZB-K and ZB-L to convert current to voltage, and the second zero-sequence current output from the ZIV sensor 32 is input to terminals ZB-K and ZB-L and then converted to a second zero-sequence voltage by the load resistor 414.

[0052] The amplification circuit 410b is configured to amplify the second zero-sequence voltage input from terminals ZB-K and ZB-L via the load resistor 414. The sampling rate of the ADC 412b is, for example, 128, when one cycle is defined as 1 / 50 [Hz] or 1 / 60 [Hz].

[0053] The load resistor 414, the amplifier circuit 410b, the filter circuit 411b, and the ADC 412b constitute a reference waveform acquisition unit that acquires the waveform of the second zero-sequence current detected by the ZIV sensor 32 as reference waveform data.

[0054] The measurement module 41 also includes terminals ZC-K and ZC-L to which the CT sensor 34 is connected, an amplification circuit 410c, a filter circuit 411c for removing harmonic noise from the output of the amplification circuit 410c, and an ADC 412c for analog / digital conversion of the output of the filter circuit 411c at a predetermined sampling period. Here, a load resistor 415 of, for example, 5.1Ω is connected between terminals ZC-K and ZC-L to convert current to voltage, and the received current output from the CT sensor 34 is input to terminals ZC-K and ZC-L and then converted to a received voltage by the load resistor 415.

[0055] The amplification circuit 410c is configured to amplify the received voltage input from terminals ZC-K and ZC-L via the load resistor 415. The sampling rate of the ADC412c is, for example, 128, when one cycle is defined as 1 / 50 [Hz] or 1 / 60 [Hz].

[0056] The load resistor 415, the amplifier circuit 410c, the filter circuit 411c, and the ADC 412c constitute a power reception waveform acquisition unit that acquires the waveform of the power reception current detected by the CT sensor 34 as power reception current waveform data.

[0057] Furthermore, the measurement module 41 includes a CPU 450 that, by executing a predetermined program, configures a high-voltage leakage current calculation unit 420 and a power receiving current calculation unit 430 in software, and a measurement data storage unit 460.

[0058] As shown in Figure 4(a), the high-voltage leakage current calculation unit 420 includes a comparison waveform zero-crossing detection unit 421, a high-voltage leakage current effective value calculation unit 422, a high-voltage leakage current average value calculation unit 423, a high-voltage leakage current alarm necessity determination unit 424, a reference waveform zero-crossing detection unit 425, a time difference calculation unit 426, a phase difference calculation unit 427, and a ground fault direction determination unit 428.

[0059] The comparison waveform zero-cross detection unit 421 detects the zero-cross point where the comparison waveform output from the ADC412a becomes zero, that is, the timing when the first zero-sequence current becomes zero. For example, the comparison waveform zero-cross detection unit 421 performs data interpolation on the comparison waveform output from the ADC412a as needed, and then detects the time of the zero-cross point.

[0060] As shown in Figure 5, the high-voltage leakage current RMS value calculation unit 422 calculates the RMS value of the comparison waveform, i.e., the RMS value of the high-voltage leakage current waveform, at cycles (periods) defined by the interval between zero-crossing points (black circles in the figure) detected by the comparison waveform zero-crossing detection unit 421. However, if the calculated RMS value of the high-voltage leakage current waveform is 30mA or less, the high-voltage leakage current RMS value calculation unit 422 replaces that RMS value with zero. Here, the cycle defined by the interval between zero-crossing points is twice the time interval between adjacent zero-crossing points. For example, if the frequency of the power supply 11 is 50Hz, the time for one cycle is 20ms, and if the frequency of the power supply 11 is 60Hz, the time for one cycle is 16.67ms.

[0061] The high-voltage leakage current average value calculation unit 423 calculates an average value obtained by averaging the effective values ​​of the high-voltage leakage current waveform calculated by the high-voltage leakage current effective value calculation unit 422 over multiple periods. For example, the high-voltage leakage current average value calculation unit 423 calculates the average value of the effective values ​​of the high-voltage leakage current waveform for four cycles, as shown in Figure 5, and uses this average value as the average current value of the high-voltage leakage current per minimum unit time. In this way, the high-voltage leakage current average value calculation unit 423 outputs the average current value of the high-voltage leakage current every four cycles. Hereafter, these four cycles will also be referred to as "one frame".

[0062] Furthermore, the high-voltage leakage current calculation unit 420 selects the minimum and maximum values ​​from the effective values ​​of the high-voltage leakage current waveform obtained in one period by the high-voltage leakage current effective value calculation unit 422, and saves them in the measurement data storage unit 460 at predetermined specified intervals as measurement data of the high-voltage leakage current waveform under normal conditions. In addition, the high-voltage leakage current calculation unit 420 saves the average current value obtained in one period by the high-voltage leakage current average value calculation unit 423 to the measurement data storage unit 460 at predetermined specified intervals as measurement data of the high-voltage leakage current waveform under normal conditions. The above specified intervals can be set from, for example, 5 minutes, 10 minutes, or 30 minutes. The measurement data of the high-voltage leakage current waveform under normal conditions stored in the measurement data storage unit 460 is transmitted to the remote monitoring center 5 via the communication module 43.

[0063] The high-voltage leakage current alarm necessity determination unit 424 determines whether the average current value of the high-voltage leakage current calculated by the high-voltage leakage current average value calculation unit 423 exceeds a predetermined high-voltage leakage current threshold. If the average current value of the high-voltage leakage current calculated by the high-voltage leakage current average value calculation unit 423 exceeds the high-voltage leakage current threshold, the high-voltage leakage current alarm necessity determination unit 424 issues a high-voltage leakage current alarm signal indicating that an excessive high-voltage leakage current has occurred.

[0064] Furthermore, the high-voltage leakage current calculation unit 420, after detecting that the average current value of the high-voltage leakage current exceeds the high-voltage leakage current threshold by the high-voltage leakage current alarm necessity determination unit 424, selects the maximum effective value from the effective values ​​of 10 frames of high-voltage leakage current waveforms and saves it in the measurement data storage unit 460 as measurement data of the high-voltage leakage current waveform during an abnormal situation. The measurement data of the high-voltage leakage current waveform during an abnormal situation stored in the measurement data storage unit 460 is transmitted to the remote monitoring center 5 via the communication module 43.

[0065] In other words, the communication module 43 transmits to the remote monitoring center 5 the high-voltage leakage current alarm signal issued by the high-voltage leakage current alarm necessity determination unit 424, and the measurement data of the high-voltage leakage current waveform calculated by the high-voltage leakage current effective value calculation unit 422 and the high-voltage leakage current average value calculation unit 423.

[0066] The reference waveform zero-cross detection unit 425 detects the zero-cross point where the reference waveform output from the ADC412b becomes zero, that is, the timing when the second zero-sequence current becomes zero. For example, the reference waveform zero-cross detection unit 425 performs data interpolation on the reference waveform output from the ADC412b as needed, and then detects the time of the zero-cross point.

[0067] As shown in Figure 6, the time difference calculation unit 426 calculates the time difference between the zero-crossing points of the high-voltage leakage current waveform detected by the comparison waveform zero-crossing detection unit 421 and the time of the zero-crossing point of the reference waveform detected by the reference waveform zero-crossing detection unit 425. The time difference calculation unit 426 calculates the time difference between the zero-crossing point of the reference waveform and the zero-crossing point of the high-voltage leakage current waveform, for example, every cycle.

[0068] The phase difference calculation unit 427 converts the time difference calculated by the time difference calculation unit 426 into a phase difference of the high-voltage leakage current waveform with respect to the phase of the reference waveform, according to the frequency of the power supply 11 (50Hz or 60Hz). The phase difference calculation unit 427 calculates the phase difference of the high-voltage leakage current waveform, for example, every cycle.

[0069] The ground fault direction determination unit 428 determines that a minor ground fault has occurred on the load 12 side of the direction determination point, which is the end of the incoming cable 15 on the substation equipment 14 side, when the phase difference calculated by the phase difference calculation unit 427 is within the phase difference range in which the polarities of the first zero-sequence current and the second zero-sequence current are the same. The phase difference range in which the polarities of the first zero-sequence current and the second zero-sequence current can be said to be the same has a range of, for example, from +150° to -35°, due to the difference in the length of the cables routed from the ZCT sensor 31 and the ZIV sensor 32 to the measurement module 41, respectively, and the influence of the frequency characteristics of the amplification circuit and filter circuit that make up the measurement module 41. In this case, the ground fault direction determination unit 428 determines that a minor ground fault has occurred on the load 12 side of the direction determination point, i.e., within the premises, when the phase difference calculated by the phase difference calculation unit 427 is within the range of +150° to -35°. On the other hand, the ground fault direction determination unit 428 determines that a minor ground fault has occurred on the power supply 11 side of the direction determination point, i.e., outside the premises, when the phase difference calculated by the phase difference calculation unit 427 is outside the range of +150° to -35°. The ground fault direction determination unit 428 determines whether the minor ground fault occurred inside or outside the premises, for example, every cycle.

[0070] Furthermore, if the phase difference calculation unit 427 is unable to calculate the phase difference correctly for any reason, such as the comparison waveform zero-crossing detection unit 421 or the reference waveform zero-crossing detection unit 425 failing to detect a zero-crossing point, the ground fault direction determination unit 428 determines that unnecessary electromagnetic induction or electrostatic induction (hereinafter also simply referred to as "induction") occurred in the ZCT sensor 31, and a normal first zero-sequence current was not output.

[0071] Furthermore, the high-voltage leakage current calculation unit 420 is configured to store measurement data of 10 judgment results (outside the premises, inside the premises, or induction) in the measurement data storage unit 460 after the high-voltage leakage current alarm necessity determination unit 424 detects that the average current value of the high-voltage leakage current exceeds the high-voltage leakage current threshold. The communication module 43 transmits the measurement data of the judgment results from the ground fault direction determination unit 428 stored in the measurement data storage unit 460 to the remote monitoring center 5.

[0072] As shown in Figure 4(b), the power receiving current calculation unit 430 includes a power receiving current zero-crossing detection unit 431, a power receiving current effective value calculation unit 432, a power receiving current average value calculation unit 433, a power receiving current alarm necessity determination unit 434, a waveform extraction unit 435, a Fourier transform calculation unit 436, a total distortion rate calculation unit 437, and a total distortion rate alarm necessity determination unit 438.

[0073] The power reception current zero-cross detection unit 431 is designed to detect the zero-cross point, that is, the timing when the power reception current waveform output from the ADC412c becomes zero level. For example, the power reception current zero-cross detection unit 431 performs data interpolation on the power reception current waveform output from the ADC412c as needed, and then detects the time of the zero-cross point.

[0074] As shown in Figure 5, the RMS value calculation unit 432 calculates the RMS value of the powered current waveform at cycles defined by the interval between zero-crossing points (black circles in the figure) detected by the powered current zero-crossing detection unit 431. Here, the cycle defined by the interval between zero-crossing points is twice the time interval between adjacent zero-crossing points.

[0075] The average value calculation unit 433 calculates an average value obtained by averaging the effective values ​​of the power reception current waveform calculated by the power reception current effective value calculation unit 432 over multiple periods. For example, the power reception current average value calculation unit 433 calculates the average value of the effective values ​​of the power reception current waveform for four cycles as shown in Figure 5, and uses this average value as the average current value of the power reception current per minimum unit time. In this way, the power reception current average value calculation unit 433 outputs the average current value of the power reception current for each frame.

[0076] Furthermore, the power receiving current calculation unit 430 selects the minimum and maximum values ​​from the RMS values ​​of the power receiving current waveform obtained in one period by the power receiving current RMS value calculation unit 432, and saves them in the measurement data storage unit 460 at predetermined specified intervals as measurement data of the power receiving current waveform during normal operation. In addition, the power receiving current calculation unit 430 saves the average value obtained in one period by the power receiving current average value calculation unit 433 to the measurement data storage unit 460 at predetermined specified intervals as measurement data of the power receiving current waveform during normal operation. The above specified intervals can be set from, for example, 5 minutes, 10 minutes, or 30 minutes. The measurement data of the power receiving current waveform during normal operation stored in the measurement data storage unit 460 is transmitted to the remote monitoring center 5 via the communication module 43.

[0077] The power receiving current alarm necessity determination unit 434 determines whether the average current value of the power receiving current calculated by the power receiving current average value calculation unit 433 exceeds a predetermined power receiving current threshold. If the average current value of the power receiving current calculated by the power receiving current average value calculation unit 433 exceeds the power receiving current threshold, the power receiving current alarm necessity determination unit 434 issues a power receiving current alarm signal indicating that an excessive power receiving current has occurred.

[0078] Furthermore, the power receiving current calculation unit 430 is configured to store the average current value of the power receiving current for one frame in the measurement data storage unit 460 as measurement data of the power receiving current waveform during an abnormal situation, when the power receiving current alarm necessity determination unit 434 detects that the average current value of the power receiving current has exceeded the power receiving current threshold. The measurement data of the power receiving current waveform during an abnormal situation stored in the measurement data storage unit 460 is transmitted to the remote monitoring center 5 via the communication module 43.

[0079] In other words, the communication module 43 transmits to the remote monitoring center 5 the power receiving current alarm signal issued by the power receiving current alarm necessity determination unit 434, and the power receiving current waveform measurement data calculated by the power receiving current effective value calculation unit 432 and the power receiving current average value calculation unit 433.

[0080] The waveform extraction unit 435 is configured to extract the power receiving current waveform for one cycle, which is defined by the interval of zero-crossing points detected by the power receiving current zero-crossing detection unit 431.

[0081] The Fourier transform calculation unit 436 performs a discrete Fourier transform or fast Fourier transform on the received current waveform for one cycle extracted by the waveform extraction unit 435 to calculate the fundamental wave component and multiple harmonic components of the received current waveform. For example, the Fourier transform calculation unit 436 calculates the fundamental wave component, the fifth harmonic component, and the seventh harmonic component of the received current waveform.

[0082] Figure 7 is a diagram illustrating the timing of the processing by the waveform extraction unit 435 and the Fourier transform calculation unit 436. First, the waveform extraction unit 435 extracts the power receiving current waveform for one cycle. Next, the Fourier transform calculation unit 436 calculates the fundamental wave component and harmonic component of the power receiving current waveform for one cycle extracted by the waveform extraction unit 435. Once the calculation by the Fourier transform calculation unit 436 on the power receiving current waveform for one cycle is completed, the waveform extraction unit 435 extracts the power receiving current waveform for another cycle, using the next zero-crossing point as the starting position. In this way, the processing by the waveform extraction unit 435 and the Fourier transform calculation unit 436 is repeated.

[0083] The total distortion calculation unit 437 calculates the total distortion, which is the ratio of the sum of multiple harmonic components calculated by the Fourier transform calculation unit 436 to the fundamental wave component. For example, the total distortion calculation unit 437 takes the average of, for example, four sets of the fundamental wave component, the fifth harmonic component, and the seventh harmonic component of the powered current waveform calculated by the Fourier transform calculation unit 436. Here, the frequency of the fundamental wave is 50Hz or 60Hz, which is the frequency of the power supply 11; the frequency of the fifth harmonic component is 250Hz or 300Hz; and the frequency of the seventh harmonic component is 350Hz or 420Hz.

[0084] The total distortion calculation unit 437 then calculates the total distortion using the average value E1 of the fundamental wave component, the average value E5 of the fifth harmonic component, and the average value E7 of the seventh harmonic component of the obtained received current waveform, as shown in equation (1) below. For example, if it takes approximately 5 seconds for the total distortion calculation unit 437 to acquire the fundamental wave component and harmonic component once, the total distortion calculation unit 437 will output the total distortion approximately every 20 seconds.

[0085]

number

[0086] Furthermore, the power receiving current calculation unit 430 saves the total distortion rate calculated by the total distortion rate calculation unit 437 to the measurement data storage unit 460 at predetermined specified intervals as measurement data for the total distortion rate under normal conditions. The specified interval can be set from, for example, 5 minutes, 10 minutes, or 30 minutes. The measurement data for the total distortion rate under normal conditions stored in the measurement data storage unit 460 is transmitted to the remote monitoring center 5 via the communication module 43.

[0087] The total distortion rate alarm necessity determination unit 438 determines whether the total distortion rate calculated by the total distortion rate calculation unit 437 exceeds a predetermined total distortion rate threshold. If the total distortion rate calculated by the total distortion rate calculation unit 437 exceeds the total distortion rate threshold, the total distortion rate alarm necessity determination unit 438 issues a total distortion rate alarm signal indicating that excessive harmonic distortion has occurred.

[0088] Furthermore, the power receiving current calculation unit 430 is configured to store the total distortion rate detected by the total distortion rate alarm necessity determination unit 438 as measurement data of the total distortion rate during abnormal conditions in the measurement data storage unit 460. The measurement data of the total distortion rate during abnormal conditions stored in the measurement data storage unit 460 is transmitted to the remote monitoring center 5 via the communication module 43.

[0089] In other words, the communication module 43 transmits to the remote monitoring center 5 the total distortion rate alarm signal issued by the total distortion rate alarm necessity determination unit 438 and the total distortion rate measurement data calculated by the total distortion rate calculation unit 437.

[0090] The remote monitoring center 5 has a display device 30 that displays at least a portion of the information transmitted from the communication module 43 to the remote monitoring center 5. At the remote monitoring center 5, monitors constantly monitor the insulation status of the high-voltage circuit 10 and the status of the power receiving and transforming equipment 14 via the display device 30. When an alarm signal is issued from various sensors installed in the high-voltage circuit 10, the monitors contact the business office from the remote monitoring center 5 and dispatch a specialist technician to the business office.

[0091] Figure 8 is a diagram illustrating the leakage current in the low-voltage circuit 50 on the secondary side of Tr19a (or 19b) installed in the high-voltage circuit 10 in the automatic remote monitoring system 1 for power receiving and transforming equipment shown in Figure 2.

[0092] Tr19a is, for example, a single-phase three-wire single-phase transformer with a primary voltage of 6600V and a secondary voltage of 210-105V, and is installed between a 6600V high-voltage circuit 10 and a load 12.

[0093] Examples of displays on the display device 30 are shown below in Figures 9(a) and (b) and Figure 10.

[0094] Figure 9(a) shows an example of the display on the display device 30 of the average current value of the high-voltage leakage current calculated by the high-voltage leakage current average value calculation unit 423 that exceeded the high-voltage leakage current threshold, the identification number of the substation (S / S), the maximum effective value of the high-voltage leakage current waveform stored in the measurement data storage unit 460, and the determination result by the ground fault direction determination unit 428.

[0095] Figure 9(b) shows an example of the display on the display device 30 of the average current value for one period of high-voltage leakage current waveform, which is stored every 30 minutes in the measurement data storage unit 460.

[0096] Figure 10 shows an example of the display on the display device 30 of the total distortion rate stored every 30 minutes in the measurement data storage unit 460.

[0097] Furthermore, the remote monitoring center 5 is configured to display at least a portion of the information transmitted from the communication module 43 to the viewing terminal 7. Figures 11(a) to (c) below show examples of the display on the viewing terminal 7.

[0098] Figure 11(a) shows an example of the user interface on the viewing terminal 7. On the left side of the display screen of the viewing terminal 7, a display period setting area 70 is displayed for setting the display period for various graphs. In the display period setting area 70, the user can arbitrarily set the display date, the display unit for that date, etc. Also, on the right side of the display screen of the viewing terminal 7, a graph selection area 71 is displayed for selecting the various graphs to be displayed for the display period set in the display period setting area 70.

[0099] Figure 11(b) shows an example of the graph display when the display date is set to May 2, 2021, the display unit to 1 hour, and the graph to display to high-voltage leakage current in the display period setting area 70 and the graph selection area 71. The graph in Figure 11(b) is an example of the display on the viewing terminal 7 of the maximum effective value of the high-voltage leakage current waveform for each hour stored in the measurement data storage unit 460.

[0100] Figure 11(c) shows an example of the graph display when the display month is set to May 2021, the display unit to 1 day, and the graph to display to high-voltage leakage current in the display period setting area 70 and the graph selection area 71. The graph in Figure 11(c) is an example of the display on the viewing terminal 7 of the maximum effective value of the high-voltage leakage current waveform for each day stored in the measurement data storage unit 460.

[0101] As described above, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment can determine whether the location of the insulation degradation where a minor ground fault has occurred is on the load side or the power supply side by calculating the phase difference between the first zero-sequence current and the second zero-sequence current based on the zero-crossing point of the first zero-sequence current detected by the ZCT sensor 31 and the zero-crossing point of the second zero-sequence current detected by the ZIV sensor 32. Furthermore, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment can remotely monitor the acquired ground fault direction determination result at the remote monitoring center 5.

[0102] Furthermore, in the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment, if at least two measurement and monitoring devices 4 each have a detachable measurement module 41, for example, multiple sensors 3 can be distributed and connected to two or more measurement modules 41. As a result, even if a measurement module 41 of one of the measurement and monitoring devices 4 fails, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment can transmit measurement data and alarm signals from the measurement modules 41 of the other measurement and monitoring devices 4 to the remote monitoring center 5, minimizing the damage from data loss.

[0103] Furthermore, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment can acquire data on high-voltage leakage current in the high-voltage circuit 10 based on the first zero-sequence current detected by the ZCT sensor 31. In addition, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment can remotely monitor the acquired high-voltage leakage current data and the high-voltage leakage current alarm signal that is issued when there is an abnormality in the acquired high-voltage leakage current data at the remote monitoring center 5.

[0104] Furthermore, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment can acquire data on the power receiving current in the high-voltage circuit 10 based on the power receiving current detected by the CT sensor 34. In addition, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment can remotely monitor the acquired power receiving current data and the power receiving current alarm signal that is issued when there is an abnormality in the acquired power receiving current data at the remote monitoring center 5.

[0105] Furthermore, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment can acquire data on the total distortion rate of the power receiving current detected by the CT sensor 34. In addition, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment can remotely monitor the acquired total distortion rate data and the total distortion rate alarm signal that is issued when there is an abnormality in the acquired total distortion rate data at the remote monitoring center 5.

[0106] Furthermore, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment enables monitors at the remote monitoring center 5 to access various measurement data and alarm signals in the high-voltage circuit 10 via the display device 30. As a result, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment facilitates the establishment of a system for promptly conducting accident investigations and determining the causes, thereby improving the quality of electrical safety.

[0107] Furthermore, the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment enables customers of the power receiving and transforming equipment 14 to access various measurement data in the high-voltage circuit 10 via a viewing terminal 7.

[0108] Furthermore, in the automatic remote monitoring system 1 for power receiving and transforming equipment according to this embodiment, the measurement and monitoring device 4 is configured to be able to detachably mount various optional modules inside, and multiple measurement and monitoring devices 4 are configured to be daisy-chain connected. In addition, the measurement and monitoring device 4 is configured to be able to daisy-chain various functional modules 45, separate from the optional modules. This makes it possible to implement a wide variety of functions to suit the environment of the power receiving and transforming equipment 14, and to delete and add functions in response to changes in the environment of the power receiving and transforming equipment 14, thereby realizing an automatic remote monitoring system 1 for power receiving and transforming equipment with excellent expandability and versatility. [Explanation of Symbols]

[0109] 1. Automatic remote monitoring system for power receiving and transforming equipment 4. Measurement and monitoring device 5 Remote Monitoring Center 6. Internet 7. Viewing terminals 10 High-voltage circuit 11 Power supply 12 loads 14 Power receiving and transforming equipment 15. Incoming Cable 16 Shielded wire 19a,19b Tr 25 Grounding point 30 Display device 31 ZCT Sensor 32 ZIV sensors 34,51 CT sensor 41 Measurement Module 42 pulse input modules 43 Communication Module 50 Low-voltage circuit 52 Low-voltage leakage current monitoring module 420 High-voltage leakage current calculation unit 421 Comparison waveform zero-cross detection unit 422 High-voltage leakage current effective value calculation unit 423 High-voltage leakage current average value calculation unit 424 High-voltage leakage current alarm necessity determination unit 425 Reference waveform zero-cross detection unit 426 Time Difference Calculation Unit 427 Phase difference calculation section 428 Ground fault direction determination unit 430 Power Receiving Current Calculation Unit 431 Power reception current zero crossing detection unit 432 Power Receiving Current RMS Value Calculation Unit 433 Average value calculation unit for received current 434 Power Receiving Current Alarm Necessity Determination Unit 435 Waveform extraction section 436 Fourier Transform Calculation Unit 437 Total Distortion Rate Calculation Unit 438 Total Distortion Rate Alarm Necessity Determination Unit

Claims

1. Multiple sensors are installed at the responsibility demarcation point of a high-voltage air switch, which is a three-phase AC circuit that supplies electricity from a power source to a load, to measure the state of the substation equipment connected via a service drop cable that constitutes part of the high-voltage circuit, or the insulation state of the high-voltage circuit. A measurement and monitoring device to which the plurality of sensors are connected, An automatic remote monitoring system for power receiving and transforming equipment comprising: a remote monitoring center that remotely monitors measurement data from at least one of the aforementioned measurement and monitoring devices; At least one of the measurement and monitoring devices is equipped with a measurement module and a communication module that are detachably mounted. Each of the aforementioned measurement and monitoring devices can be connected to a functional module via a communication interface. The aforementioned multiple observations A first zero-phase current transformer is attached to the aforementioned service drop cable and detects the first zero-phase current flowing through the service drop cable, A second zero-phase current transformer is attached to a shielded wire that is drawn out from the end of the incoming cable on the power receiving and transforming equipment side and grounded, with the polarity of the grounding point side being the same as the polarity of the power supply side of the first zero-phase current transformer. Includes, The aforementioned measurement module is A comparison waveform acquisition unit acquires the waveform of the first zero-sequence current detected by the first zero-sequence current transformer as a comparison waveform, A comparison waveform zero-cross detection unit for detecting the zero-cross point of the comparison waveform, A reference waveform acquisition unit acquires the waveform of the second zero-sequence current detected by the second zero-sequence current transformer as a reference waveform, A reference waveform zero-crossing detection unit for detecting the zero-crossing point of the reference waveform, A time difference calculation unit that calculates the time difference of the zero-crossing point of the comparison waveform with respect to the time of the zero-crossing point of the reference waveform, A phase difference calculation unit converts the time difference calculated by the time difference calculation unit into a phase difference of the comparison waveform with respect to the phase of the reference waveform, The system includes a ground fault direction determination unit that determines that a minor ground fault has occurred on the load side of the service drop cable rather than the end of the substation equipment side when the phase difference calculated by the phase difference calculation unit is within the phase difference range in which the polarity of the first zero-sequence current and the second zero-sequence current are the same, The communication module is characterized by transmitting the determination result from the ground fault direction determination unit and the monitoring result from the function module to the remote monitoring center.

2. The automatic remote monitoring system for power receiving and transforming equipment according to claim 1, characterized in that the measurement module is detachably mounted.

3. The aforementioned measurement module is A high-voltage leakage current effective value calculation unit calculates the effective value of the comparison waveform at intervals defined by the zero-crossing point intervals detected by the comparison waveform zero-crossing detection unit, A high-voltage leakage current average value calculation unit calculates an average value obtained by averaging the effective values ​​of the comparison waveform calculated by the high-voltage leakage current effective value calculation unit over multiple periods, The system further includes a high-voltage leakage current alarm necessity determination unit that determines whether the average value calculated by the high-voltage leakage current average value calculation unit exceeds a predetermined high-voltage leakage current threshold, and that issues a high-voltage leakage current alarm signal if the average value calculated by the high-voltage leakage current average value calculation unit exceeds the high-voltage leakage current threshold, The communication module transmits the high-voltage leakage current alarm signal, the effective value of the comparison waveform calculated by the high-voltage leakage current effective value calculation unit, and the average value calculated by the high-voltage leakage current average value calculation unit to the remote monitoring center, as described in claim 1 or 2.

4. The plurality of sensors further include current sensors for measuring the received current, which are attached to the secondary side of a current transformer installed in the high-voltage circuit. The aforementioned measurement module is A power receiving current waveform acquisition unit acquires the waveform of the power receiving current detected by the power receiving current measurement current sensor as the power receiving current waveform, A receiving current zero-cross detection unit for detecting the zero-cross point of the receiving current waveform, A power receiving current RMS value calculation unit calculates the RMS value of the power receiving current waveform at intervals defined by the zero-crossing point intervals detected by the power receiving current zero-crossing detection unit, A receiving current average value calculation unit calculates the average value obtained by averaging the effective value of the receiving current waveform calculated by the receiving current effective value calculation unit over multiple periods, The system further includes a power receiving current alarm necessity determination unit that determines whether the average value calculated by the power receiving current average value calculation unit exceeds a predetermined power receiving current threshold, and issues a power receiving current alarm signal if the average value calculated by the power receiving current average value calculation unit exceeds the power receiving current threshold, The automatic remote monitoring system for power receiving and transforming equipment according to claim 1 or 2, characterized in that the communication module transmits the power receiving current alarm signal, the effective value of the power receiving current waveform calculated by the power receiving current effective value calculation unit, and the average value calculated by the power receiving current average value calculation unit to the remote monitoring center.

5. The aforementioned measurement module is A waveform extraction unit extracts the receiving current waveform for one cycle defined by the interval of zero-crossing points detected by the receiving current zero-crossing detection unit, A Fourier transform calculation unit performs a Fourier transform on the one-period received current waveform extracted by the waveform extraction unit to calculate the fundamental wave component and multiple harmonic components of the received current waveform. A total distortion calculation unit calculates a total distortion ratio which is the ratio of the sum of the multiple harmonic components to the fundamental wave component. The system further includes a total distortion rate alarm necessity determination unit that determines whether the total distortion rate calculated by the total distortion rate calculation unit exceeds a predetermined total distortion rate threshold, and issues a total distortion rate alarm signal if the total distortion rate calculated by the total distortion rate calculation unit exceeds the total distortion rate threshold, The automatic remote monitoring system for power receiving and transforming equipment according to claim 4, characterized in that the communication module transmits the total distortion rate alarm signal and the total distortion rate calculated by the total distortion rate calculation unit to the remote monitoring center.

6. The automatic remote monitoring system for power receiving and transforming equipment according to claim 1 or 2, characterized in that the remote monitoring center has a display device that displays at least a portion of the information transmitted from the communication module to the remote monitoring center.

7. The system further comprises a viewing terminal connected to the aforementioned remote monitoring center via the Internet, The automatic remote monitoring system for power receiving and transforming equipment according to claim 1 or 2, characterized in that the remote monitoring center displays at least a portion of the information transmitted from the communication module to the remote monitoring center on the viewing terminal.

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