CN108490311A - Weak impact signal extraction based on power frequency sampling and separation method - Google Patents

Weak impact signal extraction based on power frequency sampling and separation method Download PDF

Info

Publication number
CN108490311A
CN108490311A CN201810240085.9A CN201810240085A CN108490311A CN 108490311 A CN108490311 A CN 108490311A CN 201810240085 A CN201810240085 A CN 201810240085A CN 108490311 A CN108490311 A CN 108490311A
Authority
CN
China
Prior art keywords
signal
sampling
power frequency
transient
current
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN201810240085.9A
Other languages
Chinese (zh)
Other versions
CN108490311B (en
Inventor
张怿宁
孟令军
齐曙光
王越杨
袁传杰
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shandong Mountain Power Technology Ltd By Share Ltd
Maintenance and Test Center of Extra High Voltage Power Transmission Co
Original Assignee
Shandong Mountain Power Technology Ltd By Share Ltd
Maintenance and Test Center of Extra High Voltage Power Transmission Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shandong Mountain Power Technology Ltd By Share Ltd, Maintenance and Test Center of Extra High Voltage Power Transmission Co filed Critical Shandong Mountain Power Technology Ltd By Share Ltd
Priority to CN201810240085.9A priority Critical patent/CN108490311B/en
Publication of CN108490311A publication Critical patent/CN108490311A/en
Application granted granted Critical
Publication of CN108490311B publication Critical patent/CN108490311B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08Locating faults in cables, transmission lines, or networks
    • G01R31/088Aspects of digital computing
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08Locating faults in cables, transmission lines, or networks
    • G01R31/081Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/085Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Theoretical Computer Science (AREA)
  • Measurement Of Resistance Or Impedance (AREA)
  • Measurement Of Current Or Voltage (AREA)

Abstract

The present invention provides the weak impact signal sampled based on power frequency extraction and separation methods, including:Line signal is acquired by high-speed sampling module, over-sampling algorithm is to sampled signal processing, change signal sampling frequencies and precision, transient signal in oversampled signals is isolated by starting filter, leak integrators processing, obtains transient signal mould maximum value, comparison signal situation of change, starting algorithm is judged according to signal intensity, provides respective response.Transient signal can be effectively extracted through the invention, and over-sampling algorithm extends the dynamic range of startup, and it is more than 60dB to make transient signal dynamic range.Equipment is high to the response sensitivity of transient signal, can be responded to the transient signal of power frequency component amplitude 0.1%.Equipment operation stability is high, strong antijamming capability.

Description

Weak impact signal extraction based on power frequency sampling and separation method
Technical field
The present invention relates to electrical equipment technical fields, and in particular to power failure distance-measuring equipment more particularly to one kind are based on The weak impact signal extraction of power frequency sampling and separation method.
Background technology
Electric power system fault distance measuring method mainly two kinds of faulty analytic approach ranging and travelling wave ranging.Traveling wave method ratio in recent years It is more popular, the new method for the high frequency transient travelling wave signal propagation time measurement distance that traveling wave method generates when being exactly according to failure.It is real In border, length, the size of transition resistance of traveling wave propagation line length can all influence the shape and amplitude of wavefront, to traveling wave For ranging, wavefront is impacted more serious, and identification wavefront is more difficult, when especially noise jamming is serious, holds It is also easy to produce erroneous judgement, influences the accuracy rate of waveform analysis.How to efficiently extract traveling wave is to carry out the premise item of traveling wave fault location Part.Travelling wave signal energy ratio power frequency component energy is much smaller, and only amplitude threshold is low as possible just can guarantee that travelling wave signal is responded, Amplitude threshold is low when interference signal is bigger, is easy for that false alarm occurs.Distance-measuring equipment requires startup weak signal small as possible, resists Interference performance is strong.
Invention content
In order to more preferably respond transient signal, anti-interference ability is improved, ensures that the reliable and stable operation of equipment, the present invention propose Weak impact signal extraction based on power frequency sampling and separation method.
The present invention adopts the following technical scheme that:
Weak impact signal extraction based on power frequency sampling and separation method, include the following steps:
Step 1: obtaining test line voltage or current signal;
Step 2: the voltage or current signal to acquisition carry out over-sampling processing;
Step 3: starting filters filter by number falls power frequency component included in the oversampled signals of step 2, Extract the transient signal in oversampled signals;
Step 4: carrying out peak value processing to transient signal;
Step 5: by comparing the Strength Changes of current sampling point signal and reference sample point signal, the class of signal is determined Type, is realized the weak impact signal extraction sampled based on power frequency and detached.
Further, it in the step 1, obtains test line voltage or current signal includes:Power frequency component, traveling wave letter Number and noise signal.
Further, in the step 2, voltage or current sampling signal to acquisition carry out over-sampling processing, pass through Sampling algorithm obtains the low frequency oversampled signals of high sampling resolution.
Further, in the step 3, the transient signal in oversampled signals is extracted, specific method is:Pass through number Start filter to handle low frequency oversampled signals, filter out the power frequency component in signal, leave including travelling wave signal and The transient signal of noise signal.
Further, in the step 4, peak value processing is carried out to transient signal, specially:The transient signal extracted It is handled by leak integrators, obtains current sample time transient signal mould maximum value.
Further, in the step 5, become by comparing the intensity of current sampling point signal and reference sample point signal Change, determines that the type of signal is specially:
According to algorithmic formula e=Ua-3U(a-3)Judge the value of e;Wherein, UaFor current sampling point signal, U(a-3)For reference Sampled point signal;
The judgements of e >=0 are fault traveling waves;
The judgements of e < 0 are interference signals.
Further, the current sampling point signal is a sampled value apart from current time recently, reference sample point It is set as fourth from the last sampled value.
Advantageous effect of the present invention:
1. the signal bandwidth coverage area of sampling channel is wide, the analysis requirement based on time domain can be met, reach 20Hz~ 1MHz。
2. starting high sensitivity, transient signal is that power frequency component amplitude 0.1% can startup separator range unit.Equipment is transported Row stability is high, transient signal accuracy of judgement.
3. the transient signal dynamic range of separation is more than 60dB.The response bandwidth of transient signal is better than 1KHz~1MHz, full The analysis requirement of sufficient electric system.
Description of the drawings
The accompanying drawings which form a part of this application are used for providing further understanding of the present application, and the application's shows Meaning property example and its explanation do not constitute the restriction to the application for explaining the application.
Fig. 1 is the weak impact signal extraction sampled based on power frequency and separation process figure;
Fig. 2 is to start filter filtering attenuation curve figure;
Fig. 3 (a)-(c) is the power frequency component sampled, step impact and its coupled signal oscillogram respectively;
Fig. 4 is the signal waveforms for starting filter process and crossing;
Fig. 5 is the processed signal waveforms of leak integrators.
Specific implementation mode
It is noted that following detailed description is all illustrative, it is intended to provide further instruction to the application.Unless another It indicates, all technical and scientific terms used herein has usual with the application person of an ordinary skill in the technical field The identical meanings of understanding.
Specific implementation mode is explained in conjunction with Fig. 1 flow charts, this example samples line voltage signal, at current signal Reason is similar.Weak impact signal uses VP=500, the step signal of period=15ms, power frequency component use VP=20000 Voltage signal;High-speed a/d module samples frequency 1MHz, sampling resolution 16Bit, sampled value are denoted as ub;Low frequency over-sampling frequency 10KHz, sampling resolution 23, sampled value is denoted as Ua
Weak impact signal based on power frequency sampling is extracted and is detached, and feature includes the following steps:
Step 1: obtaining test line voltage (electric current) signal.
Step 2: voltage (electric current) sampled signal over-sampling is handled.
Step 3: transient signal in extraction oversampled signals.
Step 4: transient signal peak value is handled.
Step 5: entry condition analyzes and determines.
It completes the weak impact signal extraction sampled based on power frequency and detaches.
Wherein, test line voltage signal is obtained described in step 1, specific method is:Pass through voltage sensor, acquisition electricity Voltage signal in net, wherein voltage sensor passband 15Hz ... 5MHz, signal enter after hardware filtering enhanced processing Sample frequency is the high-speed a/d module of 1MHz, and obtaining 16 voltage sample values, (sampled point is denoted as 0,1 ... 999999 successively, adopts Sample value is denoted as u successively0、u1……u999999).Sampled value u hereinbFor signed number.Include power frequency component, traveling wave in voltage signal Signal and noise.Fig. 3 (a)-(c) is respectively power frequency component, step impact signal and its coupled signal oscillogram.
Wherein, step 2 voltage sampling signal over-sampling is handled, and specific method is:The high frequency voltage obtained to step 1 is adopted Sample signal does over-sampling processing, so that the sample frequency of voltage signal is become 10KHz, sampling resolution is 23.Sample frequency and position Several changes is realized by over-sampling algorithm.Algorithm is according to formulaBy continuous 100 high audio sample value ub It is merged into an over sampled values Ua, over sampled values UaFor signed number.Over-sampling treated voltage signal still includes that power frequency is believed Number, travelling wave signal and noise.
Wherein, transient signal in step 3 extraction oversampled signals, specific method are:Start filters filter by number Fall the power frequency component that step 2 oversampled signals are included, filter is designed as single-pole filter, and attenuation pole 50Hz is single Pole filter transmission function isSingle-pole filter is to power frequency component Decaying is more than 80dB, normalized frequency 1000Hz;Its attenuation curve such as Fig. 4.Travelling wave signal and noise etc. are obtained by decaying Weak impact signal (transient signal).
Wherein, step 4 transient signal peak value is handled, and specific method is:After number starts filter, power frequency component Decaying, weak impact signal retain, and obtained weak signal is handled by leak integrators, obtains current time weak impact signal mould most Big value.Leak integrators treated signal such as Fig. 4, treated, and signal only has amplitude size not have direction.
Wherein, step 5 entry condition analyzes and determines, specific method is:Compare current sampling point U by comparing deviceaWith ginseng Examine sampled point U(a-3)(current time fourth from the last sampled point) change in signal strength, by starting algorithm separation interference signal and Fault traveling wave signal judges signal type.
Current sampling point and reference sample point are all peak value treated signals.Over-sampling frequency is 10khz, is corresponded in 1s Sampled point has 10,000, and current sampling point is a sampled value recently, and reference sample point is to be set as fourth from the last sampling Value.Assuming that currently there is 500 sampled values, then current sample values are the 500th, and reference sample point is the 497th sampled value.
According to algorithmic formula e=Ua-3U(a-3)Judge the value of e.E >=0 is considered that fault traveling wave, equipment start;E < 0 recognize To be interference signal, equipment does not start.
Above-mentioned, although the foregoing specific embodiments of the present invention is described with reference to the accompanying drawings, not protects model to the present invention The limitation enclosed, those skilled in the art should understand that, based on the technical solutions of the present invention, those skilled in the art are not Need to make the creative labor the various modifications or changes that can be made still within protection scope of the present invention.

Claims (7)

1. the weak impact signal extraction based on power frequency sampling and separation method, which is characterized in that include the following steps:
Step 1: obtaining test line voltage or current signal;
Step 2: the voltage or current signal to acquisition carry out over-sampling processing;
Step 3: starting filters filter by number falls power frequency component included in the oversampled signals of step 2, extract Transient signal in oversampled signals;
Step 4: carrying out peak value processing to transient signal;
Step 5: by comparing the Strength Changes of current sampling point signal and reference sample point signal, the type of signal is determined, it is real Weak impact signal now based on power frequency sampling is extracted and is detached.
2. the weak impact signal extraction based on power frequency sampling and separation method as described in claim 1, which is characterized in that described In step 1, obtains test line voltage or current signal includes:Power frequency component, travelling wave signal and noise signal.
3. the weak impact signal extraction based on power frequency sampling and separation method as described in claim 1, which is characterized in that described In step 2, voltage or current sampling signal to acquisition carry out over-sampling processing, and high sample bits are obtained by over-sampling algorithm Several low frequency oversampled signals.
4. the weak impact signal extraction based on power frequency sampling and separation method as described in claim 1, which is characterized in that described In step 3, the transient signal in oversampled signals is extracted, specific method is:Start filter to low frequency over-sampling by number Signal is handled, and the power frequency component in signal is filtered out, and leaves the transient signal including travelling wave signal and noise signal.
5. the weak impact signal extraction based on power frequency sampling and separation method as described in claim 1, which is characterized in that described In step 4, peak value processing is carried out to transient signal, specially:The transient signal extracted is handled by leak integrators, is obtained To current sample time transient signal mould maximum value.
6. the weak impact signal extraction based on power frequency sampling and separation method as described in claim 1, which is characterized in that described In step 5, by comparing the Strength Changes of current sampling point signal and reference sample point signal, determine that the type of signal is specific For:
According to algorithmic formula e=Ua-3U(a-3)Judge the value of e;Wherein, UaFor current sampling point signal, U(a-3)For reference sample Point signal;
The judgements of e >=0 are fault traveling waves;
The judgements of e < 0 are interference signals.
7. the weak impact signal extraction based on power frequency sampling and separation method as described in claim 1, which is characterized in that described Current sampling point signal is a sampled value apart from current time recently, and reference sample point is set as fourth from the last sampling Value.
CN201810240085.9A 2018-03-22 2018-03-22 Weak impact signal extraction and separation method based on power frequency sampling Active CN108490311B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201810240085.9A CN108490311B (en) 2018-03-22 2018-03-22 Weak impact signal extraction and separation method based on power frequency sampling

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810240085.9A CN108490311B (en) 2018-03-22 2018-03-22 Weak impact signal extraction and separation method based on power frequency sampling

Publications (2)

Publication Number Publication Date
CN108490311A true CN108490311A (en) 2018-09-04
CN108490311B CN108490311B (en) 2020-11-13

Family

ID=63319193

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810240085.9A Active CN108490311B (en) 2018-03-22 2018-03-22 Weak impact signal extraction and separation method based on power frequency sampling

Country Status (1)

Country Link
CN (1) CN108490311B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109581114A (en) * 2018-12-11 2019-04-05 武汉水院电气有限责任公司 A kind of power frequency component and impact signal superposition phase control circuit
CN111896837A (en) * 2019-05-05 2020-11-06 中国电力科学研究院有限公司 Transient current signal extraction method and device

Citations (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5233538A (en) * 1990-04-02 1993-08-03 Square D Company Waveform capturing arrangement in a distributed power network
CN1657959A (en) * 2005-03-11 2005-08-24 天津大学 Rang-measuring method for transmission line one-phase earth fault of small current neutral grounding system
CN101464478A (en) * 2009-01-15 2009-06-24 华北电力大学 Voltage fluctuation flickering measurement method based on digital synchronization carrier wave coherent demodulation technology
CN101846716A (en) * 2009-03-27 2010-09-29 北海银河科技继保电气有限公司 Method for quickly catching power grid fault start point
JP2013150087A (en) * 2012-01-18 2013-08-01 Hioki Ee Corp A/d converter inspection apparatus and a/d converter inspection method
CN103278747A (en) * 2013-06-03 2013-09-04 东南大学 High-tension transmission line single-ended traveling wave fault distance detection method combined with time-frequency characteristics
KR20130101790A (en) * 2012-03-06 2013-09-16 이현창 Installation route survey
CN203275468U (en) * 2013-05-13 2013-11-06 海南电力技术研究院 Novel Rogowski coil for measuring power transmission line fault traveling wave current
CN103513159A (en) * 2013-09-24 2014-01-15 中国南方电网有限责任公司超高压输电公司检修试验中心 Method and device for locating fault on direct current grounding electrode circuit
CN203465354U (en) * 2013-08-29 2014-03-05 浙江万向太阳能有限公司 Detection device of DC power supply insulation resistance to ground
CN103823159A (en) * 2014-03-13 2014-05-28 国家电网公司 Distribution network fault distance measuring device based on fault transient state travelling wave collection and distance measuring method
CN104121985A (en) * 2013-04-29 2014-10-29 艾默生电气(美国)控股公司(智利)有限公司 Selective decimation and analysis of oversampled data
CN105021953A (en) * 2015-06-10 2015-11-04 国网上海市电力公司 A transformer substation grounding grid corrosion detection system and method based on earth's surface magnetic induction intensity
CN105337612A (en) * 2015-12-09 2016-02-17 杨艳 Software phase locked ring capable of filtering out power frequency interference
CN105988063A (en) * 2015-03-16 2016-10-05 武汉三相电力科技有限公司 Power transmission line fault hidden risk integrated on-line monitoring method and device
CN106526413A (en) * 2016-10-13 2017-03-22 国家电网公司 Off-line ground fault detection system and method
CN106959402A (en) * 2017-05-03 2017-07-18 国网安徽省电力公司培训中心 A kind of Little Current Ground Connection System and determination methods
CN107290626A (en) * 2017-06-28 2017-10-24 合肥市闵葵电力工程有限公司 A kind of power line monitoring system
CN107703416A (en) * 2017-08-29 2018-02-16 珠海许继电气有限公司 Small current neutral grounding system Secondary cases singlephase earth fault Section Location and system

Patent Citations (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5233538A (en) * 1990-04-02 1993-08-03 Square D Company Waveform capturing arrangement in a distributed power network
CN1657959A (en) * 2005-03-11 2005-08-24 天津大学 Rang-measuring method for transmission line one-phase earth fault of small current neutral grounding system
CN101464478A (en) * 2009-01-15 2009-06-24 华北电力大学 Voltage fluctuation flickering measurement method based on digital synchronization carrier wave coherent demodulation technology
CN101846716A (en) * 2009-03-27 2010-09-29 北海银河科技继保电气有限公司 Method for quickly catching power grid fault start point
JP2013150087A (en) * 2012-01-18 2013-08-01 Hioki Ee Corp A/d converter inspection apparatus and a/d converter inspection method
KR20130101790A (en) * 2012-03-06 2013-09-16 이현창 Installation route survey
CN104121985A (en) * 2013-04-29 2014-10-29 艾默生电气(美国)控股公司(智利)有限公司 Selective decimation and analysis of oversampled data
CN203275468U (en) * 2013-05-13 2013-11-06 海南电力技术研究院 Novel Rogowski coil for measuring power transmission line fault traveling wave current
CN103278747A (en) * 2013-06-03 2013-09-04 东南大学 High-tension transmission line single-ended traveling wave fault distance detection method combined with time-frequency characteristics
CN203465354U (en) * 2013-08-29 2014-03-05 浙江万向太阳能有限公司 Detection device of DC power supply insulation resistance to ground
CN103513159A (en) * 2013-09-24 2014-01-15 中国南方电网有限责任公司超高压输电公司检修试验中心 Method and device for locating fault on direct current grounding electrode circuit
CN103823159A (en) * 2014-03-13 2014-05-28 国家电网公司 Distribution network fault distance measuring device based on fault transient state travelling wave collection and distance measuring method
CN105988063A (en) * 2015-03-16 2016-10-05 武汉三相电力科技有限公司 Power transmission line fault hidden risk integrated on-line monitoring method and device
CN105021953A (en) * 2015-06-10 2015-11-04 国网上海市电力公司 A transformer substation grounding grid corrosion detection system and method based on earth's surface magnetic induction intensity
CN105337612A (en) * 2015-12-09 2016-02-17 杨艳 Software phase locked ring capable of filtering out power frequency interference
CN106526413A (en) * 2016-10-13 2017-03-22 国家电网公司 Off-line ground fault detection system and method
CN106959402A (en) * 2017-05-03 2017-07-18 国网安徽省电力公司培训中心 A kind of Little Current Ground Connection System and determination methods
CN107290626A (en) * 2017-06-28 2017-10-24 合肥市闵葵电力工程有限公司 A kind of power line monitoring system
CN107703416A (en) * 2017-08-29 2018-02-16 珠海许继电气有限公司 Small current neutral grounding system Secondary cases singlephase earth fault Section Location and system

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
张怿宁 等: "脉冲注入法和单端故障行波法相结合的直流输电系统接地极线路故障测距", 《电力系统保护与控制》 *
张怿宁: "基于两种算法融合的接地极线路故障测距", 《高电压技术》 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109581114A (en) * 2018-12-11 2019-04-05 武汉水院电气有限责任公司 A kind of power frequency component and impact signal superposition phase control circuit
CN111896837A (en) * 2019-05-05 2020-11-06 中国电力科学研究院有限公司 Transient current signal extraction method and device
CN111896837B (en) * 2019-05-05 2024-04-16 中国电力科学研究院有限公司 Transient current signal extraction method and device

Also Published As

Publication number Publication date
CN108490311B (en) 2020-11-13

Similar Documents

Publication Publication Date Title
CN109901031B (en) Signal-to-noise separation method for partial discharge signal and information data processing terminal
CN106771922B (en) A kind of high-tension electricity system of detecting partial discharge in equipment and Recognition of Partial Discharge
CN110007197B (en) Series arc fault detection system and detection method
CN102539527A (en) GIS (gas insulated substation) partial discharge mode identification method based on ultrasonic testing
CN103175897B (en) A kind of high-speed switch hurt recognition methods based on vibration signal end-point detection
CN109212391A (en) Take into account the signal processing of partial discharge method and power cable partial discharge positioning method of DISCHARGE PULSES EXTRACTION and signal denoising
CN101196547A (en) Live testing apparatus for local discharge based on ultrasound assistance
CN108196164B (en) Method for extracting cable fault point discharge sound signal under strong background noise
CN101710166A (en) Method for monitoring partial discharge of power cable connector on line
CN105044566A (en) GIS partial discharge fault detection method based on characteristic ultrahigh frequency signal
CN108490311A (en) Weak impact signal extraction based on power frequency sampling and separation method
CN106197650A (en) A kind of method judging that audio signal is noiseless
CN109541455A (en) A kind of OLTC impact characteristics extracting method based on S-transformation time-frequency spectrum SVD noise reduction
CN107561424A (en) Series direct current arc fault recognition methods based on sliding DFT
CN106501673B (en) A kind of normal harmonic wave method of discrimination based on transmission line of electricity hidden danger electric discharge measured current traveling wave
CN104991171B (en) GIS partial discharge frequency dividing failure collection of illustrative plates method for drafting based on ultra-high frequency signal
CN113358972A (en) High-resistance ground fault line selection method based on line transient characteristics
CN101680915B (en) Method and device for evaluating fast current changes
CN216848010U (en) Cable partial discharge online monitoring device for edge calculation
CN105559771B (en) A kind of method and device of electrocardiosignal quality testing
CN105807204B (en) Hardware Trojan horse detection method based on frequency spectrum refinement
CN104655914A (en) Method and device for detecting interference signals and local discharging signals of GIS equipment
CN110161376A (en) A kind of traveling wave fault moment extraction algorithm
CN112861328B (en) Generator damping evaluation device and method based on random response signals
CN110109007A (en) Method and device for acquiring insulation resistance values of inner side and outer side of relay

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant