CN107525996A - A kind of series compensation device voltage limiter On-line Monitoring of Leakage Current method and system - Google Patents
A kind of series compensation device voltage limiter On-line Monitoring of Leakage Current method and system Download PDFInfo
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- G—PHYSICS
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Abstract
The invention discloses a kind of series compensation device voltage limiter On-line Monitoring of Leakage Current method and system, methods described uses low current sensor and current transformer synchronous acquisition series compensation device main capacitor electric current and each voltage limiter leakage current, the phase and amplitude of each electric current is calculated, and then using the electric current of main capacitor as reference data, calculate the phase angle of voltage limiter voltage and leakage current and the current in resistance property of each voltage limiter, by above-mentioned result of calculation compared with threshold value, to determine that corresponding voltage limiter whether there is potential faults；The system includes more low current sensors, current transformer, platform data unit, optical fiber insulated column and ground monitoring unit, more low current sensors are used for the leakage current for measuring each voltage limiter, current transformer is used to measure main capacitor electric current, platform data unit is used for processing data and draws result of calculation, optical fiber insulated column is used to carry out data transmission, and ground monitoring unit is done according to result of calculation to be judged.
Description
Technical Field
The invention relates to the field of power equipment monitoring, in particular to a method and a system for online monitoring of leakage current of a voltage limiter of a series compensation device.
Background
At present, a 220 kV-1000 kV series compensation device put into operation in China has been continuously operated for many years, the overall operation is stable, each series compensation platform is generally provided with more than ten to dozens of metal oxide voltage limiters, and each voltage limiter is internally formed by connecting a plurality of metal oxide resistance cards in parallel. The metal oxide voltage limiter has excellent nonlinear protection characteristics, and can protect a main capacitor in time and does not need a series compensation device to exit in a short time when a fault occurs outside a power grid area; the availability of the series compensation device is greatly improved, and the disturbance of a power grid is reduced; although routine preventive tests are carried out on most voltage limiter equipment every year by the power operation unit, the defects of wetting, deterioration and the like of part of the voltage limiters cannot be detected through the tests, faults such as pressure release of the metal oxide voltage limiters and the like occur, the voltage limiters cannot bear overvoltage and are damaged, so that series compensation quits operation, the safe and stable operation of a power grid is influenced, and the loss of transmission capacity is caused.
Disclosure of Invention
In order to solve the problem that the metal oxide voltage limiter of the series compensation device has fault hidden danger in the prior art, the invention provides a method and a system for monitoring the leakage current of the voltage limiter of the series compensation device on line, wherein the leakage current of the metal oxide voltage limiter can change greatly only under the condition that the voltage limiter is seriously damped or aged, the change is not large when the voltage limiter is slightly damped and aged inside, the measurement of the leakage current cannot be accurately concluded, and the resistive current in the leakage current can change greatly even when the voltage limiter is slightly damped or aged;
the online monitoring method for the leakage current of the voltage limiter of the series compensation device comprises the following steps:
step 1, measuring the leakage current of each metal oxide voltage limiter and measuring the current of a main capacitor of a series compensation device;
step 2, calculating the leakage current of each metal oxide voltage limiter and the amplitude and the phase of the current of a main capacitor of the series compensation device;
step 3, calculating the resistive current in the leakage current of each metal oxide voltage limiter by taking the current of a main capacitor of the series compensation device as a reference;
step 4, comparing the calculation results of the step 2 and the step 3 with the corresponding normal working threshold interval, and confirming the working state of each metal oxide voltage limiter;
furthermore, the platform data module synchronously samples the leakage current of each metal oxide voltage limiter and the current of the main capacitor for N cycles, wherein the sampling interval time is T, N is more than or equal to 10 and less than or equal to 20, N is an integer, and T is more than or equal to 50us and less than or equal to 100 us;
further, calculating the leakage current of each metal oxide voltage limiter and the amplitude and the phase of a main capacitor of the series compensation device by a harmonic analysis method or a fast Fourier transform method;
furthermore, the main capacitor is formed by connecting a plurality of capacitor units in series and parallel, and the equivalent total capacitance of the main capacitor is C∑The equivalent total resistance of the main capacitor is R∑The voltage phase of the main capacitorComprises the following steps:
wherein, omega is the frequency,is the main capacitor current phase;
further, the equivalent total capacitance C of the main capacitor∑The capacitance of the capacitor units is obtained by series-parallel connection, and the capacitance of the capacitor units is obtained by factory test or field actual measurement; the equivalent total resistance R of the main capacitor∑The equivalent resistances of the capacitor units are obtained by series-parallel connection, the equivalent resistances of the capacitor units are obtained by a power consumption test, the series-parallel connection mode is that m capacitor units are connected in series to form a capacitor unit group, then n capacitor unit groups are connected in parallel, the capacitor units are equivalent to be formed by connecting capacitors and the equivalent resistances in parallel, wherein m and n are natural numbers;
further, the resistive current I in the leakage current of each metal oxide voltage limiterR-movXComprises the following steps:
IR-movX＝Imov-Xcos(θX+X)
said Imov-XThe amplitude of the leakage current of the Xth metal oxide voltage limiter; thetaXThe power factor angle of the voltage and the leakage current of the Xth metal oxide voltage limiter;Xphase correction parameters of the Xth metal oxide; the main capacitor is connected in parallel with the metal oxide voltage limiter, and thetaXThe calculation method is as follows:
wherein X is more than or equal to 1 and less than or equal to k, X is an integer, and k is the number of metal oxide voltage limiters.
Further, a micro-current sensor is used for measuring the leakage current of each metal oxide voltage limiter, and a current transformer is used for measuring a main capacitor of the series compensation device;
furthermore, the measurement of the leakage current of each metal oxide voltage limiter and the measurement of the current of the main capacitor are synchronous sampling measurement; the measurement result is preprocessed through analog-to-digital conversion before the calculation in the step 2 and the step 3 is carried out by using the measurement result;
the leakage current on-line monitoring system of the voltage limiter of the series compensation device comprises:
the plurality of micro-current sensors are used for collecting the leakage current of the corresponding metal oxide voltage limiters, and the output ends of the plurality of micro-current sensors are connected with the platform data unit;
the current transformer is used for collecting the current of a main capacitor of the series compensation device, and the output end of the current transformer is connected with the platform data unit;
the platform data unit is used for synchronously sampling the leakage current of the metal oxide voltage limiters acquired by the plurality of micro-current sensors and the current of the main capacitor of the series compensation device acquired by the current transformer, performing analog-to-digital conversion, processing and calculating each data, and transmitting the calculation result data to the ground monitoring unit through the optical fiber insulation column;
the optical fiber insulation column is used for providing a data transmission channel from the platform data unit to the ground monitoring unit;
the ground monitoring unit is used for receiving and storing each data sent by the platform data unit and judging whether the voltage limiter of the series compensation device is abnormal or not according to the comparison result of each data and the normal working threshold interval;
furthermore, the micro-current sensor is of a through structure, and a lead wire led out from the bottom of the metal oxide voltage limiter penetrates through the micro-current sensor to be connected with a low-voltage end bus bar of the metal oxide voltage limiter; the low-voltage end busbar of the metal oxide voltage limiter is connected with a low-voltage bus of the series compensation device;
furthermore, the micro-current sensor and the current transformer are connected with the platform data unit through a shielded cable;
furthermore, the main capacitor is formed by connecting a plurality of capacitor units in series and parallel, and the equivalent total capacitance C of the main capacitor∑The capacitance of the capacitor units is obtained by series-parallel connection, and the capacitance of the capacitor units is obtained by factory test or field actual measurement; the equivalent total resistance R of the main capacitor∑The equivalent resistances of the plurality of capacitor units are obtained by series-parallel connection, and the equivalent resistances of the capacitor units are obtained by a power consumption test; the series-parallel connection mode is that m capacitor units are connected in series to form a capacitor unit group, then n capacitor unit groups are connected in parallel, the capacitor units are equivalently formed by connecting a capacitor and an equivalent resistor in parallel, wherein m and n are natural numbers;
further, the data output by the platform data unit to the ground monitoring unit includes: the leakage current value of each metal oxide voltage limiter, the voltage value of the main capacitor, the current value of the main capacitor, the power factor angle of the voltage and the leakage current of each metal oxide voltage limiter and the resistive current value of each metal oxide voltage limiter.
The invention has the beneficial effects that: the technical scheme of the invention provides an online monitoring method and system for leakage current of voltage limiters of a series compensation device, wherein the method and system provide a method for extracting resistive current of each voltage limiter by taking current of a main capacitor as a reference, and based on the method, whether hidden danger exists in the metal oxide voltage limiters of the corresponding series compensation device is evaluated by monitoring the leakage current and the resistive current in real time; the working reliability of the series compensation device and the metal oxide voltage limiter thereof is greatly improved; meanwhile, the method and the system do not need to additionally install a voltage transformer or a voltage divider on the series compensation platform, and the problems of small available space, compact arrangement, small insulation margin and the like of the series compensation platform equipment are solved.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
fig. 1 is a flowchart of an online leakage current monitoring method for a voltage limiter of a series compensation apparatus according to an embodiment of the present invention;
fig. 2 is a structural diagram of an online leakage current monitoring system for a voltage limiter of a series compensation apparatus according to an embodiment of the present invention;
FIG. 3 is a diagram illustrating waveforms and phase relationships of a main capacitor current and a leakage current of a metal oxide voltage limiter of a series compensation apparatus according to an embodiment of the present invention;
fig. 4 is a schematic diagram illustrating a connection relationship between capacitor units in a series compensation main capacitor according to an embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flowchart of an online leakage current monitoring method for a voltage limiter of a series compensation apparatus according to an embodiment of the present invention; according to the method steps shown in the flow chart, a method for extracting the resistive current of each voltage limiter by taking the current of the main capacitor as a reference is adopted, and whether hidden danger exists in the metal oxide voltage limiter of the corresponding series compensation device is evaluated through real-time monitoring of leakage current and the resistive current on the basis;
the online monitoring method for the leakage current of the voltage limiter of the series compensation device comprises the following steps:
step 101, measuring the leakage current of each metal oxide voltage limiter and measuring the current of a main capacitor of a series compensation device;
the micro-current sensor is used for measuring the leakage current of each metal oxide voltage limiter, and the current transformer is used for a main capacitor of the measuring series compensation device; the series compensation device comprises k metal oxide voltage limiters, and a micro-current sensor is arranged on each metal oxide voltage limiter; preferably, the micro-current sensor is of a through structure, and a lead led out from the bottom of the metal oxide voltage limiter penetrates through the micro-current sensor and is connected with a low-voltage end bus bar of the metal oxide voltage limiter; a current transformer is arranged on a low-voltage end wire of a main capacitor of the series compensation device; in the present embodiment, the micro-current sensor has a central aperture of 30mm to 100 mm; the measurement range of the micro-current sensor is 50 muA to 100mA, and the maximum output voltage signal is +/-7V; the rated current of the primary side of the current transformer is the rated current of the series compensation platform, and the secondary output current is 1A;
preferably, for compact layout, the micro-current sensor is installed at the position of the bottom of the metal oxide voltage limiter, which is close to the bus side;
the platform data unit synchronously collects leakage current measured by each micro current sensor and main capacitor current measured by the current transformer and performs analog-to-digital conversion; the synchronous acquisition synchronously samples the leakage current of each metal oxide voltage limiter and the current of a main capacitor for N cycles, the sampling interval time is T, wherein N is more than or equal to 10 and less than or equal to 20, N is an integer, and T is more than or equal to 50us and less than or equal to 100 us; if N is less than or equal to 10, the data volume is too small, and the calculation precision is low; if N is more than or equal to 20, the data volume is too large, a large amount of hardware memory resources are consumed, and the calculation efficiency is too low;
102, calculating the leakage current of each metal oxide voltage limiter and the amplitude and the phase of the current of a main capacitor of the series compensation device;
after the platform data unit is completely collected, the same time is taken as t0At the starting point, a complete cycle sampling value is selected from N sampled cycles, and the power frequency fundamental component I of the current of the main capacitor of the series compensation device is calculatedcapAnd phaseAnd the power frequency fundamental component I of the leakage current of each of the k metal oxide voltage limitersmov-1To Imov-kAnd phaseToThe relationship between the waveform, amplitude and phase of the main current of the series compensation device and the leakage current of the metal oxide voltage limiter as shown in fig. 3 is obtained, and the waveform formula is as follows:
wherein k is a natural number and is less than or equal to the number of the metal oxide voltage limiters;
preferably, the method for calculating the amplitude and the phase is a fast fourier transform method;
preferably, the method for calculating the amplitude and the phase is a harmonic analysis method;
103, calculating the resistive current in the leakage current of each metal oxide voltage limiter by taking the current of a main capacitor of the series compensation device as a reference;
as shown in fig. 4, the equivalent total capacitance C of the main capacitor∑The capacitance of the capacitor units is obtained by series-parallel connection, and the capacitance of the capacitor units is obtained by factory test or field actual measurement; the equivalent total resistance R of the main capacitor∑The equivalent resistances of the capacitor units are obtained by series-parallel connection of the equivalent resistances of the capacitor units, the equivalent resistances of the capacitor units are obtained by a power consumption test, the series-parallel connection mode is as shown in fig. 4, m capacitor units are connected in series to form a capacitor unit group, then n capacitor unit groups are connected in parallel, the equivalent resistance comprises a plurality of components such as conductor loss, dielectric loss, parallel discharge resistance loss and the like in the capacitor units, and each capacitor unit is equivalent to a circuit formed by connecting a capacitor and the equivalent resistance in parallel; wherein m and n are natural numbers;
the equivalent circuit of the series compensation main capacitor in fig. 4 can be obtained as follows:
solving to obtain the voltage phase of the main capacitorComprises the following steps:
the main capacitor and the metal oxide voltage limiter of the series compensation device are connected in parallel between the high-voltage bus and the low-voltage bus, so that the voltage at two ends of the main capacitor is equal to the voltage at two ends of the metal oxide voltage limiter; calculating each limit based on the current of the series compensation main capacitorPower factor angle theta of transformer voltage and leakage currentkComprises the following steps:
the resistive current of each metal oxide voltage limiter is:
IR-movk＝Imov-kcos(θk+k)
wherein,kthe phase correction coefficient of the kth metal oxide voltage limiter is shown, k is a natural number and is less than or equal to the number of the metal oxide voltage limiters;
104, comparing the calculation result with the corresponding normal working threshold interval, confirming the working state of each metal oxide voltage limiter and giving an evaluation result;
the calculation result includes a leakage current I per metal oxidemov-kPower factor angle theta of metal oxide voltage limiter voltage and leakage currentkResistive current IR-movkAnd main capacitor voltage UcapMain capacitor current Icap；
The step of confirming the working state of each metal maintenance infinite transformer is carried out according to the voltage U of the main capacitorcapAnd current IcapDetermining a leakage current threshold range, a resistive current range and a power factor angle range of the voltage limiter; leakage current I of each voltage limitermov-kAngle of power factor thetakResistive current IR-movkAnd comparing the range with a threshold range, and determining whether the range is exceeded or not to obtain an evaluation result.
Fig. 2 is a structural diagram of an online leakage current monitoring system for a voltage limiter of a series compensation apparatus according to an embodiment of the present invention; the device acquires synchronous data through a plurality of micro-current sensors and current transformers, performs analog-to-digital conversion and processing calculation through a platform data unit, obtains settlement results, and sends the settlement results to a ground monitoring unit through an optical fiber insulating column, and the ground monitoring unit analyzes and evaluates the monitoring results; the leakage current on-line monitoring system of the voltage limiter of the series compensation device comprises:
the system comprises a plurality of micro-current sensors CT-1 to CT-k, a platform data unit and a plurality of micro-current sensors, wherein the plurality of micro-current sensors are used for collecting leakage currents of corresponding metal oxide voltage limiters, and output ends of the plurality of micro-current sensors are connected with the platform data unit;
the current transformer CT is used for collecting current of a main capacitor of the series compensation device, and the output end of the current transformer CT is connected with the platform data unit 201;
the platform data unit 201 is used for synchronously sampling the leakage current of the metal oxide voltage limiter collected by the plurality of micro-current sensors and the current of the main capacitor of the series compensation device collected by the current transformer, performing analog-to-digital conversion, processing and calculating each data, and sending the calculation result data to the ground monitoring unit 203 through the optical fiber insulation column 202;
the optical fiber insulation column 202, the optical fiber insulation column 202 is used for providing a data transmission channel from the platform data unit to the ground monitoring unit 203;
the ground monitoring unit 203 is used for receiving and storing each data sent by the platform data unit 201, and judging whether the voltage limiter of the series compensation device is abnormal or not according to the comparison result of each data and the normal working threshold interval;
furthermore, the series compensation device comprises k metal oxide voltage limiters with the serial numbers from MOV-1 to MOV-k, a micro-current sensor is arranged on each metal oxide voltage limiter, and the serial numbers of the corresponding micro-current sensors are from CT-1 to CT-k in sequence; preferably, the micro-current sensor is of a through structure, and a lead led out from the bottom of the metal oxide voltage limiter penetrates through the micro-current sensor and is connected with a low-voltage end bus bar of the metal oxide voltage limiter; a current transformer CT is arranged on a low-voltage end wire of a main capacitor of the series compensation device; the current transformer CT is of a straight-through structure; in the present embodiment, the micro-current sensor has a central aperture of 30mm to 100 mm; the measurement range of the micro-current sensor is 50 muA to 100mA, and the maximum output voltage signal is +/-7V; the rated current of the primary side of the current transformer is the rated current of the series compensation platform, and the secondary output current is 1A;
preferably, for compact layout, the micro-current sensor is installed at the position of the bottom of the metal oxide voltage limiter, which is close to the bus side;
preferably, the micro-current sensor and the current transformer are connected with the platform data unit through a shielded cable;
further, the method for calculating the current amplitude and phase by the platform data unit comprises a fast Fourier transform method and a harmonic analysis method;
further, the main capacitor of the series compensation device and the metal oxide voltage limiter are connected between the high-voltage bus and the low-voltage bus in parallel;
furthermore, the main capacitor is formed by connecting a plurality of capacitor units in series and parallel, and the equivalent total capacitance C of the main capacitor∑The capacitance of the capacitor units is obtained by series-parallel connection, and the capacitance of the capacitor units is obtained by factory test or field actual measurement; the equivalent total resistance R of the main capacitor∑The equivalent resistances of the plurality of capacitor units are obtained by series-parallel connection, and the equivalent resistances of the capacitor units are obtained by a power consumption test;
further, the data output by the platform data unit to the ground monitoring unit includes: the leakage current value of each metal oxide voltage limiter, the voltage value of the main capacitor, the current value of the main capacitor, the power factor angle of the voltage and the leakage current of each metal oxide voltage limiter and the resistive current value of each metal oxide voltage limiter.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (11)
1. An online monitoring method for leakage current of a voltage limiter of a series compensation device, comprising the following steps:
step 1, measuring the leakage current of each metal oxide voltage limiter and measuring the current of a main capacitor of a series compensation device;
step 2, calculating the leakage current of each metal oxide voltage limiter and the amplitude and the phase of the current of a main capacitor of the series compensation device;
step 3, calculating the resistive current in the leakage current of each metal oxide voltage limiter by taking the current of a main capacitor of the series compensation device as a reference;
and 4, comparing the calculation results of the steps 2 and 3 with the corresponding normal working threshold interval, and confirming the working state of each metal oxide voltage limiter.
2. The method of claim 1, wherein: the platform data module synchronously samples the leakage current of each metal oxide voltage limiter and the current of the main capacitor for N cycles, wherein the sampling interval time is T, N is more than or equal to 10 and less than or equal to 20, N is an integer, and T is more than or equal to 50us and less than or equal to 100 us.
3. The method of claim 1, wherein: and calculating the leakage current of each metal oxide voltage limiter and the amplitude and the phase of the main capacitor of the series compensation device by a harmonic analysis method or a fast Fourier transform method.
4. A method according to claim 1 or 3, characterized in that: the main capacitor is formed by connecting a plurality of capacitor units in series and parallel, and the equivalent total capacitance of the main capacitor is C∑The equivalent total resistance of the main capacitor is R∑The voltage phase of the main capacitorComprises the following steps:
wherein, omega is the frequency,the main capacitor current phase.
5. The method of claim 4, wherein: the resistive current I in the leakage current of each metal oxide voltage limiterR-movXComprises the following steps:
IR-movX＝Imov-Xcos(θX+X)
said Imov-XThe amplitude of the leakage current of the Xth metal oxide voltage limiter; thetaXThe power factor angle of the voltage and the leakage current of the Xth metal oxide voltage limiter;Xphase correction parameters of the Xth metal oxide; the main capacitor is connected in parallel with the metal oxide voltage limiter, and thetaXThe calculation method is as follows:
wherein X is more than or equal to 1 and less than or equal to k, X is an integer, and k is the number of metal oxide voltage limiters.
6. The method of claim 1, wherein: the micro-current sensor is used for measuring the leakage current of each metal oxide voltage limiter, and the current transformer is used for a main capacitor of the measuring series compensation device.
7. The method of claim 1, wherein: the measurement of the leakage current of each metal oxide voltage limiter and the measurement of the current of the main capacitor are synchronous sampling measurement; the measurement results are pre-processed by analog-to-digital conversion before being used for the calculations of step 2 and step 3.
8. An on-line monitoring system for leakage current of a voltage limiter of a series compensation device, the system comprising:
the plurality of micro-current sensors are used for collecting the leakage current of the corresponding metal oxide voltage limiters, and the output ends of the plurality of micro-current sensors are connected with the platform data unit;
the current transformer is used for collecting the current of a main capacitor of the series compensation device, and the output end of the current transformer is connected with the platform data unit;
the platform data unit is used for synchronously sampling the leakage current of the metal oxide voltage limiter acquired by the plurality of micro-current sensors and the current of the main capacitor of the series compensation device acquired by the current transformer, performing analog-to-digital conversion, processing and calculating each data, and transmitting the calculation result data to the ground monitoring unit through the light insulation column;
the optical fiber insulation column is used for providing a data transmission channel from the platform data unit to the ground monitoring unit;
and the ground monitoring unit is used for receiving and storing each data sent by the platform data unit and judging whether the voltage limiter of the series compensation device is abnormal or not according to the comparison result of each data and the normal working threshold interval.
9. The system of claim 8, wherein: the micro-current sensor is of a through structure, and a lead wire led out from the bottom of the metal oxide voltage limiter penetrates through the micro-current sensor to be connected with a low-voltage end bus bar of the metal oxide voltage limiter; and a low-voltage end bus bar of the metal oxide voltage limiter is connected with a low-voltage bus of the series compensation device.
10. The system of claim 8, wherein: the micro-current sensor and the current transformer are connected with the platform data unit through a shielded cable.
11. The system of claim 8, wherein: the data output by the platform data unit to the ground monitoring unit comprises: the leakage current value of each metal oxide voltage limiter, the voltage value of the main capacitor, the current value of the main capacitor, the power factor angle of the voltage and the leakage current of each metal oxide voltage limiter and the resistive current value of each metal oxide voltage limiter.
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Cited By (5)
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| CN108899993A (en) * | 2018-05-09 | 2018-11-27 | 北京国网普瑞特高压输电技术有限公司 | Voltage limiter status monitoring subsystem based on series compensation state on_line monitoring system |
| CN109061275A (en) * | 2018-05-23 | 2018-12-21 | 中国电力科学研究院有限公司 | A kind of distributed On-line Monitoring of Leakage Current method and system of series compensation device voltage limiter |
| CN109742727A (en) * | 2018-12-21 | 2019-05-10 | 国网湖南省电力有限公司 | A kind of judgment method of low pressure 400V leakage current |
| CN112081586A (en) * | 2020-10-10 | 2020-12-15 | 中国石油天然气集团有限公司 | Multi-spectrum stratum boundary far detection method and device |
| CN113466600A (en) * | 2021-08-03 | 2021-10-01 | 国网四川省电力公司营销服务中心 | Circuit, method and use for detecting the effect of leakage current on a current transformer |
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| CN109742727A (en) * | 2018-12-21 | 2019-05-10 | 国网湖南省电力有限公司 | A kind of judgment method of low pressure 400V leakage current |
| CN109742727B (en) * | 2018-12-21 | 2020-03-17 | 国网湖南省电力有限公司 | Method for judging low-voltage 400V leakage current |
| CN112081586A (en) * | 2020-10-10 | 2020-12-15 | 中国石油天然气集团有限公司 | Multi-spectrum stratum boundary far detection method and device |
| CN112081586B (en) * | 2020-10-10 | 2024-04-30 | 中国石油天然气集团有限公司 | Multi-spectrum stratum boundary far detection method and device |
| CN113466600A (en) * | 2021-08-03 | 2021-10-01 | 国网四川省电力公司营销服务中心 | Circuit, method and use for detecting the effect of leakage current on a current transformer |
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