CN108037423A - A kind of high-voltage cable insulating on-Line Monitor Device and method based on double differential CT methods - Google Patents
A kind of high-voltage cable insulating on-Line Monitor Device and method based on double differential CT methods Download PDFInfo
- Publication number
- CN108037423A CN108037423A CN201711303073.8A CN201711303073A CN108037423A CN 108037423 A CN108037423 A CN 108037423A CN 201711303073 A CN201711303073 A CN 201711303073A CN 108037423 A CN108037423 A CN 108037423A
- Authority
- CN
- China
- Prior art keywords
- phase
- current
- differential
- cable
- differential value
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 37
- 238000002247 constant time method Methods 0.000 title claims abstract description 24
- 238000009413 insulation Methods 0.000 claims abstract description 64
- 238000012544 monitoring process Methods 0.000 claims abstract description 25
- 238000004891 communication Methods 0.000 claims abstract description 22
- 238000012806 monitoring device Methods 0.000 claims abstract description 15
- 230000032683 aging Effects 0.000 claims description 17
- 238000005070 sampling Methods 0.000 claims description 16
- 230000008859 change Effects 0.000 claims description 14
- 239000000284 extract Substances 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 230000001939 inductive effect Effects 0.000 claims description 6
- 230000009466 transformation Effects 0.000 claims description 6
- GNFTZDOKVXKIBK-UHFFFAOYSA-N 3-(2-methoxyethoxy)benzohydrazide Chemical compound COCCOC1=CC=CC(C(=O)NN)=C1 GNFTZDOKVXKIBK-UHFFFAOYSA-N 0.000 claims description 5
- FGUUSXIOTUKUDN-IBGZPJMESA-N C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 Chemical compound C1(=CC=CC=C1)N1C2=C(NC([C@H](C1)NC=1OC(=NN=1)C1=CC=CC=C1)=O)C=CC=C2 FGUUSXIOTUKUDN-IBGZPJMESA-N 0.000 claims description 5
- 230000005540 biological transmission Effects 0.000 claims description 4
- 239000011347 resin Substances 0.000 claims description 4
- 229920005989 resin Polymers 0.000 claims description 4
- 238000001914 filtration Methods 0.000 claims description 3
- 238000012546 transfer Methods 0.000 claims description 3
- 239000011159 matrix material Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000001514 detection method Methods 0.000 description 3
- 239000004703 cross-linked polyethylene Substances 0.000 description 2
- 229920003020 cross-linked polyethylene Polymers 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000003449 preventive effect Effects 0.000 description 2
- 238000003745 diagnosis Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000016507 interphase Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
- G01R31/1263—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
- G01R31/1272—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
- G01R31/14—Circuits therefor, e.g. for generating test voltages, sensing circuits
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Resistance Or Impedance (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
本发明一种基于双差动CT法的高压电缆绝缘在线监测装置与方法，包括6个穿心式电流互感器、有源滤波放大器、Zigbee无线通信模块以及计算机；所述6个穿心式电流互感器用于获取电缆电路首/末端A，B，C三相电流差动信号；所述有源滤波放大器用于对采集信号进行过滤后放大，并传输至Zigbee无线通信模块；所述Zigbee无线通信模块用于接收电流差动信号，并传输至计算机；所述计算机用于储存首末端A，B，C三相电流差动信号并计算二次差动值，继而判断电缆线路绝缘状况。本发明实现了在负载不对称情况下交流高压电缆线路绝缘的在线监测。
The present invention is an on-line monitoring device and method for high-voltage cable insulation based on a double differential CT method, comprising six through-hole current transformers, an active filter amplifier, a Zigbee wireless communication module and a computer; the six through-hole current transformers The transformer is used to obtain the three-phase current differential signal of the first/end A, B, and C of the cable circuit; the active filter amplifier is used to filter and amplify the collected signal, and transmit it to the Zigbee wireless communication module; the Zigbee wireless communication The module is used to receive the current differential signal and transmit it to the computer; the computer is used to store the A, B, C three-phase current differential signal at the head end and calculate the secondary differential value, and then judge the insulation status of the cable line. The invention realizes the on-line monitoring of the AC high-voltage cable line insulation under the condition of load asymmetry.
Description
技术领域technical field
本发明涉及高压电缆绝缘在线监测领域，尤其涉及一种基于双差动CT法的高压电缆绝缘在线监测装置及方法。The invention relates to the field of on-line monitoring of high-voltage cable insulation, in particular to an on-line monitoring device and method for high-voltage cable insulation based on a double differential CT method.
背景技术Background technique
随着电网中运行电压等级的提高，高压电力电缆在电网运行中大量敷设。随着电缆运行电压等级的提高，对电缆绝缘性能要求不断提高，随之而来的是对于电缆安全运行问题的担忧。With the improvement of the operating voltage level in the power grid, a large number of high-voltage power cables are laid in the operation of the power grid. With the improvement of the operating voltage level of cables, the requirements for cable insulation performance continue to increase, followed by concerns about the safe operation of cables.
目前在电力系统中被广泛使用的仍是定期停电预防性试验的方法，此方法属于离线检测。对尚未投入运行的电缆检测效果良好，但由于这种方法需要停电检测，无法检测正在运行中的电缆。进行定期停电预防性试验会造成供电中断，原先绝缘状况良好的电缆在经过反复的试验后绝缘老化甚至击穿。At present, the method of regular blackout preventive test is still widely used in the power system, which belongs to off-line detection. The detection effect on cables that have not been put into operation is good, but because this method requires power failure detection, it cannot detect cables that are in operation. Regular power outage preventive tests will cause power supply interruption, and cables with good insulation conditions will age or even break down after repeated tests.
因此对电缆的运行状况进行在线监测和诊断变得极为必要,及时预测和发现电缆可能的故障，已成为保障电力系统电缆线路安全运行的必要途径。在线监测方法中的直流分量法目前不适用于初期投运的电缆，对运行较长时间的电缆仍然适用。直流叠加法、低频叠加法和交流叠加法由于在高压线路中三相中性点通常是直接接地，无法在电缆线芯上叠加直流、交流电源，所以不适用于高电压XLPE电缆绝缘在线监测。国内外专家学者和国际电力权威组织一致推荐局部放电试验作为XLPE绝缘电力电缆绝缘状况评价的最佳方法。但是电缆的局部放电信号微弱、波形复杂多变难以区分，因此工程中难以实现现场的在线监测。tanδ法即从电压互感器取出电压信号，从电流互感器获取流经电缆绝缘的工频电流，测量二者相位差值，从而获得tanδ。但是电压互感器的相对误差可能已超过tanδ的相对误差，该方法难以投入现场使用。接地电流法可用来判断电缆绝缘状态，但在金属护层交叉互联下接电线上的电流几乎为零，且易受现场噪声信号干扰，上述在线监测方法均未考虑电缆末端负载变化对监测结果的影响，在高压电缆三相负载不平衡误差较大。Therefore, it is extremely necessary to conduct online monitoring and diagnosis on the operation status of cables, and to predict and discover possible cable faults in time has become a necessary way to ensure the safe operation of power system cable lines. The DC component method in the on-line monitoring method is currently not suitable for cables that are initially put into operation, but is still applicable to cables that have been in operation for a long time. The DC superposition method, low frequency superposition method and AC superposition method are not suitable for high-voltage XLPE cable insulation on-line monitoring because the three-phase neutral point is usually directly grounded in high-voltage lines, and it is impossible to superimpose DC and AC power on the cable core. Domestic and foreign experts and scholars and international power authority organizations unanimously recommend the partial discharge test as the best method for evaluating the insulation status of XLPE insulated power cables. However, the partial discharge signal of the cable is weak, and the waveform is complex and changeable, which is difficult to distinguish, so it is difficult to realize on-line monitoring in the project. The tanδ method is to take the voltage signal from the voltage transformer, obtain the power frequency current flowing through the cable insulation from the current transformer, and measure the phase difference between the two to obtain tanδ. However, the relative error of the voltage transformer may have exceeded the relative error of tanδ, and this method is difficult to put into field use. The ground current method can be used to judge the insulation status of cables, but the current on the connecting wires under the cross-connection of the metal sheath is almost zero, and it is easily interfered by field noise signals. The above online monitoring methods do not consider the influence of the load change at the end of the cable on the monitoring results. Influenced by the three-phase load unbalance error in high-voltage cables.
发明内容Contents of the invention
本发明的目的是为了解决三相负载不平衡条件下高压电缆绝缘在线监测技术问题，提供一种基于双差动CT法的高压电缆绝缘在线监测装置及方法。The purpose of the present invention is to solve the technical problem of on-line monitoring of high-voltage cable insulation under the condition of unbalanced three-phase load, and provide an on-line monitoring device and method of high-voltage cable insulation based on double differential CT method.
本发明采用如下装置实现：The present invention adopts following device to realize:
一种基于双差动CT法的高压电缆绝缘在线监测装置，包括6个穿心式电流互感器、有源滤波放大器、Zigbee无线通信模块以及计算机；A high-voltage cable insulation on-line monitoring device based on double differential CT method, including 6 feed-through current transformers, active filter amplifier, Zigbee wireless communication module and computer;
所述6个穿心式电流互感器用于获取电缆电路首/末端A，B，C三相电流差动信号；所述6个穿心式电流互感器中，第一穿心式电流互感器、第二穿心式电流互感器以及第三穿心式电流互感器分别安装在电缆线路首端A，B，C三相电缆终端底部；第一穿心式电流互感器、第二穿心式电流互感器以及第三穿心式电流互感器的二次线圈采用串联方式相连接，采集电缆线路首端A，B，C三相电流差动信号；第四穿心式电流互感器、第五穿心式电流互感器以及第六穿心式电流互感器分别安装在电缆线路末端A，B，C三相电缆终端底部；第四穿心式电流互感器、第五穿心式电流互感器以及第六穿心式电流互感器的二次线圈采用串联方式相连接，采集电缆线路末端A，B，C三相电流差动信号；所述电流互感器均为开合式电流互感器，外壳采用不饱和树脂绝缘；The 6 feed-through current transformers are used to obtain the three-phase current differential signals of the cable circuit head/end A, B, and C; among the 6 feed-through current transformers, the first feed-through current transformer, The second feed-through current transformer and the third feed-through current transformer are respectively installed at the bottom of the three-phase cable terminals A, B, and C at the head end of the cable line; the first feed-through current transformer, the second feed-through current transformer The transformer and the secondary coil of the third through-type current transformer are connected in series to collect the three-phase current differential signals of A, B and C at the head end of the cable line; the fourth through-type current transformer, the fifth through-type current transformer The core-type current transformer and the sixth core-type current transformer are respectively installed at the bottom of the three-phase cable terminals A, B, and C at the end of the cable line; the fourth core-type current transformer, the fifth core-type current transformer and the The secondary coils of the six-through-type current transformers are connected in series to collect the three-phase current differential signals of A, B, and C at the end of the cable line; resin insulation;
所述有源滤波放大器用于对采集信号进行过滤后放大，并传输至Zigbee无线通信模块；The active filter amplifier is used to amplify the collected signal after filtering, and transmit it to the Zigbee wireless communication module;
所述Zigbee无线通信模块用于接收电流差动信号，并传输至计算机；所述计算机用于储存首末端A，B，C三相电流差动信号并计算二次差动值，继而判断电缆线路绝缘状况。The Zigbee wireless communication module is used to receive the current differential signal and transmit it to the computer; the computer is used to store the head-end A, B, C three-phase current differential signal and calculate the secondary differential value, and then judge the cable line Insulation condition.
进一步地，所述A，B，C三相电流差动信号，包括A，B，C三相电流之间的差动值以及A，B，C三相电流之和的差动。Further, the A, B, C three-phase current differential signal includes the differential value among the A, B, C three-phase currents and the differential value of the sum of the A, B, C three-phase currents.
进一步地，所述A，B，C三相电流差动信号由电流信号的幅值差动和相位差动构成。Further, the A, B, and C three-phase current differential signals are composed of amplitude differentials and phase differentials of current signals.
进一步地，所述6个穿心式电流互感器的额定功率为5W，变比为200/5，安装在电流互感器二次侧的6个采样电阻均为0.2Ω的精密无感电阻。Further, the rated power of the six feedthrough current transformers is 5W, the transformation ratio is 200/5, and the six sampling resistors installed on the secondary side of the current transformers are precision non-inductive resistors of 0.2Ω.
进一步地，所述采集电缆线路首端A，B，C三相电流差动信号或采集电缆线路首端A，B，C三相电流差动信号的方法具体为：首末两端三个采样电阻分别串联，A，B，C三相电流信号矢量相加，经采样电阻上的I/V转换后获得。Further, the method of collecting the three-phase current differential signal at the head end A, B, and C of the cable line or collecting the three-phase current differential signal at the head end A, B, and C of the cable line is specifically: three sampling at the first and last ends Resistors are connected in series respectively, A, B, and C three-phase current signals are added vectorially, and obtained after I/V conversion on the sampling resistor.
进一步地，所述有源滤波放大器采用太阳能电池和或超级电容供电；所述Zigbee无线通信模块包括单片机、RF收发器、以及SPI接口；所述RF收发器为CC2420射频芯片，工作频率2.4GHz，数据传输速率250kb/s；通过SPI接口与MSP430F149单片机通信；所述计算机中用LABVIEW软件分析计算首末电流信号变化，提取特征信号，对电缆绝缘做出判断并发出预警。Further, the active filter amplifier is powered by solar cells and or supercapacitors; the Zigbee wireless communication module includes a single-chip microcomputer, an RF transceiver, and an SPI interface; the RF transceiver is a CC2420 radio frequency chip with an operating frequency of 2.4GHz, The data transmission rate is 250kb/s; it communicates with the MSP430F149 microcontroller through the SPI interface; the computer uses LABVIEW software to analyze and calculate the change of the first and last current signal, extract the characteristic signal, make a judgment on the cable insulation and issue an early warning.
本发明可以采取如下方法实现：The present invention can take following method to realize:
一种基于双差动CT法的高压电缆绝缘在线监测方法，包括：A method for on-line monitoring of high-voltage cable insulation based on a double differential CT method, comprising:
步骤a、使用电流互感器分别采集A，B，C三相电缆首端电流与末端电流并计算A，B，C三相电缆首端电流之和以及A，B，C三相电缆末端电流之和；将电流信号经有源滤波放大器滤波放大后通过Zigbee无线通信模块将信号发送给上位机；Step a. Use current transformers to collect the current at the head end and the end current of the three-phase cables A, B, and C respectively, and calculate the sum of the currents at the head end of the three-phase cables A, B, and C and the current at the end of the three-phase cables A, B, and C. and; after the current signal is filtered and amplified by the active filter amplifier, the signal is sent to the host computer through the Zigbee wireless communication module;
步骤b、在上位机中计算电缆末端A，B，C三相电流之间的差动值与三相电流之和的差动值，判断末端负载变化；Step b. Calculate the differential value between the three-phase currents at the cable ends A, B, and C and the differential value of the sum of the three-phase currents in the host computer to determine the change in the terminal load;
步骤c、同时计算电缆首端A，B，C三相电流之间的差动值与三相电流之和的差动值，判断负载及电缆泄漏电流的不对称程度；Step c. Simultaneously calculate the differential value between the three-phase currents at the first end of the cable A, B, and C and the differential value of the sum of the three-phase currents to determine the asymmetry of the load and cable leakage current;
步骤d、再将首端电流之和的差动值减去三相电缆末端三相电流之和的差动值，得到三相电流之和的二次差动值作为三相电缆泄漏电流之和；将首端A，B，C三相电流之间的差动值减去末端A，B，C三相电流之间的差动值，得到三相电流之间的二次差动值作为三相电缆泄漏电流之差；Step d, then subtract the differential value of the sum of the three-phase currents at the end of the three-phase cable from the differential value of the sum of the current at the head end to obtain the secondary differential value of the sum of the three-phase currents as the sum of the leakage currents of the three-phase cables ;Subtract the differential value between the three-phase currents at the first end A, B, and C from the differential value between the three-phase currents at the end A, B, and C, and obtain the secondary differential value between the three-phase currents as the three-phase current The difference between the leakage current of the phase cables;
步骤e、判定三相电流之和二次差动值的相位与设定绝缘老化预警值是否一致，若不一致时转向步骤f，一致时转向步骤g；Step e, determine whether the phase of the sum of the three-phase currents and the secondary differential value is consistent with the set insulation aging warning value, if not consistent, turn to step f, and if consistent, turn to step g;
步骤f、将三相电流之间二次差动值的相位与设定绝缘老化预警值作对比，并判断各相电缆绝缘老化特征；Step f, comparing the phase of the secondary differential value between the three-phase currents with the set insulation aging warning value, and judging the insulation aging characteristics of each phase cable;
步骤g、生成在线监测报表，包括末端A，B，C三相电流之间的差动值；首端A，B，C三相电流之间的差动值；A，B，C三相电流之间的二次差动值；末端A，B，C三相电流之和的差动值；首端A，B，C三相电流之和的差动值；A，B，C三相电流之和的二次差动值以及电缆线路绝缘分析结果。Step g. Generate an online monitoring report, including the differential value between the three-phase currents at the end A, B, and C; the differential value between the three-phase currents at the first end A, B, and C; the three-phase currents at A, B, and C The secondary differential value between; the differential value of the sum of the three-phase currents of A, B, and C at the end; the differential value of the sum of the three-phase currents of A, B, and C at the head end; the three-phase current of A, B, and C The secondary differential value of the sum and the cable line insulation analysis results.
进一步地，所述电流互感器的额定功率为5W，变比为200/5，安装在电流互感器二次侧的6个采样电阻均为0.2Ω的精密无感电阻。Further, the rated power of the current transformer is 5W, the transformation ratio is 200/5, and the six sampling resistors installed on the secondary side of the current transformer are precision non-inductive resistors of 0.2Ω.
进一步地，所述采集A，B，C三相电缆首端电流与末端电流方法具体为：首末两端三个采样电阻分别串联，A，B，C三相电流信号矢量相加，经采样电阻上的I/V转换后获得。Further, the method of collecting the current at the head end and the end current of the A, B, and C three-phase cables is specifically as follows: three sampling resistors at the first and last ends are respectively connected in series, the A, B, and C three-phase current signals are vector-added, and after sampling Obtained after I/V conversion on the resistor.
进一步地，所述有源滤波放大器采用太阳能电池和超级电容供电；所述Zigbee无线通信模块包括单片机、RF收发器、以及SPI接口；所述RF收发器为CC2420射频芯片，工作频率2.4GHz，数据传输速率250kb/s；通过SPI接口与MSP430F149单片机通信；所述上位机中用LABVIEW软件分析计算首末电流信号变化，提取特征信号，对电缆绝缘做出判断并发出预警。Further, the active filter amplifier is powered by solar cells and supercapacitors; the Zigbee wireless communication module includes a single-chip microcomputer, an RF transceiver, and an SPI interface; the RF transceiver is a CC2420 radio frequency chip with a working frequency of 2.4GHz, and The transmission rate is 250kb/s; it communicates with the MSP430F149 single-chip microcomputer through the SPI interface; the LABVIEW software is used in the host computer to analyze and calculate the change of the first and last current signal, extract the characteristic signal, make a judgment on the cable insulation and issue an early warning.
本发明有如下积极效果：本发明提供一种基于双差动CT法的高压电缆绝缘在线监测装置及方法，提取了电缆线路绝缘老化后首端电流的差动信号和末端电流的差动信号，与现有电缆在线监测技术相比，能够反映电缆末端负载的变化，同时首末两端差动信号之差构成的二次差动能够有效避免末端负载变化对在线监测结果的影响，准确反映多种电缆线路绝缘老化情况。The present invention has the following positive effects: the present invention provides a high-voltage cable insulation on-line monitoring device and method based on the double differential CT method, which extracts the differential signal of the head-end current and the differential signal of the end current after the insulation of the cable line is aged, and is compatible with Compared with the existing cable online monitoring technology, it can reflect the change of the load at the end of the cable. At the same time, the secondary differential formed by the difference between the differential signals at the first and last ends can effectively avoid the influence of the change of the end load on the online monitoring results, and accurately reflect various Aging condition of cable line insulation.
附图说明Description of drawings
图1是一种基于双差动CT法的高压电缆绝缘在线监测系统实施例流程图；Fig. 1 is a flow chart of an embodiment of a high-voltage cable insulation on-line monitoring system based on a double differential CT method;
图2是一种基于双差动CT法的高压电缆绝缘在线监测方法实施例流程图；Fig. 2 is a flow chart of an embodiment of a high-voltage cable insulation on-line monitoring method based on a double differential CT method;
图3是电缆终端电流互感器上信号采集方式；Fig. 3 is the signal acquisition method on the cable terminal current transformer;
图4是一种基于双差动CT法的高压电缆绝缘在线监测装置结构示意图；Fig. 4 is a schematic structural diagram of a high-voltage cable insulation on-line monitoring device based on the double differential CT method;
具体实施方式Detailed ways
本发明给出了一种基于双差动CT法的高压电缆绝缘在线监测装置与方法实施例，为了使本技术领域的人员更好地理解本发明实施例中的技术方案，并使本发明的上述目的、特征和优点能够更加明显易懂，下面结合附图对本发明中技术方案作进一步详细的说明：The present invention provides an embodiment of a high-voltage cable insulation on-line monitoring device and method based on a double differential CT method, in order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the present invention The above objects, features and advantages can be more obvious and understandable, and the technical solution in the present invention will be further described in detail below in conjunction with the accompanying drawings:
本发明首选提供一种基于双差动CT法的高压电缆绝缘在线监测装置实施例，如图1所示：包括6个穿心式电流互感器10、有源滤波放大器20、Zigbee无线通信模块30以及计算机40；The present invention firstly provides an embodiment of a high-voltage cable insulation on-line monitoring device based on the double differential CT method, as shown in Figure 1: it includes 6 through-hole current transformers 10, an active filter amplifier 20, and a Zigbee wireless communication module 30 and a computer 40;
所述6个穿心式电流互感器10用于获取电缆电路首/末端A，B，C三相电流差动信号；所述6个穿心式电流互感器中，第一穿心式电流互感器、第二穿心式电流互感器以及第三穿心式电流互感器分别安装在电缆线路首端A，B，C三相电缆终端底部；第一穿心式电流互感器101、第二穿心式电流互感器102以及第三穿心式电流互感器103的二次线圈采用串联方式相连接，采集电缆线路首端A，B，C三相电流差动信号；第四穿心式电流互感器104、第五穿心式电流互感器105以及第六穿心式电流互感器106分别安装在电缆线路末端A，B，C三相电缆终端底部；第四穿心式电流互感器、第五穿心式电流互感器以及第六穿心式电流互感器的二次线圈采用串联方式相连接，采集电缆线路末端A，B，C三相电流差动信号；所述电流互感器均为开合式电流互感器，外壳采用不饱和树脂绝缘；The 6 feed-through current transformers 10 are used to obtain the three-phase current differential signals of the cable circuit head/end A, B, and C; among the 6 feed-through current transformers, the first feed-through current transformer The device, the second through-type current transformer and the third through-type current transformer are respectively installed at the bottom of the three-phase cable terminals A, B and C at the head end of the cable line; the first through-type current transformer 101, the second through-type current transformer The core-type current transformer 102 and the secondary coil of the third through-type current transformer 103 are connected in series to collect three-phase current differential signals at the head end A, B, and C of the cable line; the fourth through-type current transformer The device 104, the fifth through-type current transformer 105 and the sixth through-type current transformer 106 are respectively installed at the bottom of the three-phase cable terminals A, B and C at the end of the cable line; the fourth through-type current transformer, the fifth through-type current transformer The secondary coils of the feed-through current transformer and the sixth feed-through current transformer are connected in series to collect the three-phase current differential signals of A, B, and C at the end of the cable line; the current transformers are all split type Current transformer, the shell is insulated with unsaturated resin;
所述有源滤波放大器20用于对采集信号进行过滤后放大，并传输至Zigbee无线通信模块30；The active filter amplifier 20 is used to amplify the collected signal after filtering, and transmit it to the Zigbee wireless communication module 30;
所述Zigbee无线通信模块30用于接收电流差动信号，并传输至计算机40；所述计算机用于储存首末端A，B，C三相电流差动信号并计算二次差动值，继而判断电缆线路绝缘状况。The Zigbee wireless communication module 30 is used to receive the current differential signal and transmit it to the computer 40; the computer is used to store the head-end A, B, C three-phase current differential signal and calculate the secondary differential value, and then judge Condition of cable insulation.
优选地，所述A，B，C三相电流差动信号，包括A，B，C三相电流之间的差动值以及A，B，C三相电流之和的差动。Preferably, the A, B, C three-phase current differential signal includes the differential value among the A, B, C three-phase currents and the differential value of the sum of the A, B, C three-phase currents.
优选地，所述A，B，C三相电流差动信号由电流信号的幅值差动和相位差动构成。Preferably, the A, B, C three-phase current differential signals are composed of amplitude differentials and phase differentials of current signals.
优选地，所述6个穿心式电流互感器的额定功率为5W，变比为200/5，安装在电流互感器二次侧的6个采样电阻均为0.2Ω的精密无感电阻。Preferably, the rated power of the 6 feedthrough current transformers is 5W, the transformation ratio is 200/5, and the 6 sampling resistors installed on the secondary side of the current transformers are precision non-inductive resistors of 0.2Ω.
优选地，所述采集电缆线路首端A，B，C三相电流差动信号或采集电缆线路首端A，B，C三相电流差动信号的方法具体为：首末两端三个采样电阻分别串联，A，B，C三相电流信号矢量相加，经采样电阻上的I/V转换后获得。Preferably, the method for collecting the three-phase current differential signals at the head end A, B, and C of the cable line or the method for collecting the three-phase current differential signals at the head end A, B, and C of the cable line is specifically: three samples at the first and last ends Resistors are connected in series respectively, A, B, and C three-phase current signals are added vectorially, and obtained after I/V conversion on the sampling resistor.
优选地，所述有源滤波放大器采用太阳能电池和或超级电容供电；所述Zigbee无线通信模块包括单片机、RF收发器、以及SPI接口；所述RF收发器为CC2420射频芯片，工作频率2.4GHz，数据传输速率250kb/s；通过SPI接口与MSP430F149单片机通信；所述计算机中用LABVIEW软件分析计算首末电流信号变化，提取特征信号，对电缆绝缘做出判断并发出预警。Preferably, the active filter amplifier is powered by solar cells and or supercapacitors; the Zigbee wireless communication module includes a single-chip microcomputer, an RF transceiver, and an SPI interface; the RF transceiver is a CC2420 radio frequency chip with an operating frequency of 2.4GHz, The data transmission rate is 250kb/s; it communicates with the MSP430F149 microcontroller through the SPI interface; the computer uses LABVIEW software to analyze and calculate the change of the first and last current signal, extract the characteristic signal, make a judgment on the cable insulation and issue an early warning.
本发明还提供一种方法实施例，如图2所示：The present invention also provides a method embodiment, as shown in Figure 2:
一种基于双差动CT法的高压电缆绝缘在线监测方法，包括：A method for on-line monitoring of high-voltage cable insulation based on a double differential CT method, comprising:
S201、步骤a、使用电流互感器分别采集A，B，C三相电缆首端电流与末端电流并计算A，B，C三相电缆首端电流之和以及A，B，C三相电缆末端电流之和；将电流信号经有源滤波放大器滤波放大后通过Zigbee无线通信模块将信号发送给上位机；S201. Step a. Use current transformers to collect the current at the head end and the end current of the three-phase cables A, B, and C respectively, and calculate the sum of the currents at the head end of the A, B, and C three-phase cables and the ends of the A, B, and C three-phase cables The sum of the current; the current signal is filtered and amplified by the active filter amplifier, and then the signal is sent to the host computer through the Zigbee wireless communication module;
S202、步骤b、在上位机中计算电缆末端A，B，C三相电流之间的差动值与三相电流之和的差动值，判断末端负载变化；S202. Step b. Calculate the differential value between the three-phase currents at the cable ends A, B, and C in the host computer and the differential value of the sum of the three-phase currents, and determine the change in the terminal load;
S203、步骤c、同时计算电缆首端A，B，C三相电流之间的差动值与三相电流之和的差动值，判断负载及电缆泄漏电流的不对称程度；S203. Step c. Simultaneously calculate the differential value between the three-phase currents at the first end of the cable A, B, and C and the differential value of the sum of the three-phase currents to determine the asymmetry of the load and cable leakage current;
其中步骤S202与S203可以互换；并不影响实施效果；Wherein steps S202 and S203 are interchangeable; the implementation effect is not affected;
S204、步骤d、再将首端电流之和的差动值减去三相电缆末端三相电流之和的差动值，得到三相电流之和的二次差动值作为三相电缆泄漏电流之和；将首端A，B，C三相电流之间的差动值减去末端A，B，C三相电流之间的差动值，得到三相电流之间的二次差动值作为三相电缆泄漏电流之差；S204, step d, subtract the differential value of the sum of the three-phase currents at the end of the three-phase cable from the differential value of the sum of the current at the head end, and obtain the secondary differential value of the sum of the three-phase currents as the leakage current of the three-phase cable The sum; subtract the differential value between the three-phase currents at the first end A, B, and C from the differential value between the three-phase currents at the end A, B, and C to obtain the secondary differential value between the three-phase currents as the difference between the three-phase cable leakage currents;
S205、步骤e、判定三相电流之和二次差动值的相位与设定绝缘老化预警值是否一致，若不一致时转向步骤(6)，一致时转向步骤(7)；S205, step e, determining whether the phase of the sum of the three-phase currents and the secondary differential value is consistent with the set insulation aging warning value, if not consistent, turn to step (6), and if consistent, turn to step (7);
S206、步骤f、将三相电流之间二次差动值的相位与设定绝缘老化预警值作对比，并判断各相电缆绝缘老化特征；S206, step f, comparing the phase of the secondary differential value between the three-phase currents with the set insulation aging warning value, and judging the insulation aging characteristics of each phase cable;
S207、步骤g、生成在线监测报表，包括末端A，B，C三相电流之间的差动值；首端A，B，C三相电流之间的差动值；A，B，C三相电流之间的二次差动值；末端A，B，C三相电流之和的差动值；首端A，B，C三相电流之和的差动值；A，B，C三相电流之和的二次差动值以及电缆线路绝缘分析结果。S207, step g, generating an online monitoring report, including the differential value between the terminal A, B, and C three-phase currents; the differential value between the head-end A, B, and C three-phase currents; A, B, and C The secondary differential value between the phase currents; the differential value of the sum of the three-phase currents at the end A, B, and C; the differential value of the sum of the three-phase currents at the first end A, B, and C; the three-phase current of A, B, and C The secondary differential value of the sum of the phase currents and the results of the cable line insulation analysis.
优选地，所述电流互感器的额定功率为5W，变比为200/5，安装在电流互感器二次侧的6个采样电阻均为0.2Ω的精密无感电阻，其中，工作频率2.4GHz，数据传输速率250kb/s；Preferably, the rated power of the current transformer is 5W, the transformation ratio is 200/5, and the six sampling resistors installed on the secondary side of the current transformer are precision non-inductive resistors of 0.2Ω, wherein the working frequency is 2.4GHz , the data transfer rate is 250kb/s;
优选地，所述采集A，B，C三相电缆首端电流与末端电流方法如图3所示具体为：首末两端三个采样电阻分别串联，A，B，C三相电流信号矢量相加，经采样电阻上的I/V转换后获得。Preferably, the method of collecting A, B, and C three-phase cable head-end currents and end-end currents is specifically as shown in Figure 3: three sampling resistors at the first and last ends are respectively connected in series, A, B, and C three-phase current signal vector Addition, obtained after I/V conversion on the sampling resistor.
优选地，所述有源滤波放大器采用太阳能电池和超级电容供电；Preferably, the active filter amplifier is powered by solar cells and supercapacitors;
其中，太阳能电池维持有源滤波放大器日常工作，超级电容能够保证在线监测设备在特殊情况下短时间内不断电。Among them, the solar battery maintains the daily work of the active filter amplifier, and the supercapacitor can ensure that the online monitoring equipment is continuously powered in a short period of time under special circumstances.
所述Zigbee无线通信模块包括单片机、RF收发器、以及SPI接口；所述RF收发器为CC2420射频芯片，工作频率2.4GHz，数据传输速率250kb/s；通过SPI接口与MSP430F149单片机通信；所述上位机中用LABVIEW软件分析计算首末电流信号变化，提取特征信号，对电缆绝缘做出判断并发出预警。Described Zigbee wireless communication module comprises single-chip microcomputer, RF transceiver, and SPI interface; Described RF transceiver is CC2420 radio frequency chip, operating frequency 2.4GHz, data transfer rate 250kb/s; Communicate with MSP430F149 single-chip microcomputer by SPI interface; The LABVIEW software is used in the machine to analyze and calculate the change of the first and last current signal, extract the characteristic signal, make a judgment on the cable insulation and issue an early warning.
其中，符合如下特征信号时可以判断单相或两相电缆线路绝缘老化，发出预警。Among them, when the following characteristic signals are met, the insulation aging of single-phase or two-phase cable lines can be judged and an early warning can be issued.
三相电缆线路绝缘同时老化时，不同相之间的老化程度不同，泄漏电流相位角随之变化，即三相电流之间二次差动值的相位随之变化。代表各相泄漏电流相位，代表原先两相泄漏电流相位差，代表新的两相泄漏电流相位差，i＝A,B,C，建立相位差矩阵老化后，泄漏电流相位差矩阵变为相间差动系数建立相间差动矩阵当未老化时，kij＝0，老化越严重，kij越大，根据相间差动矩阵[kij]的变化判断各相绝缘老化情况。When the insulation of the three-phase cable line is aging at the same time, the aging degree between different phases is different, and the phase angle of the leakage current changes accordingly, that is, the phase of the secondary differential value between the three-phase currents changes accordingly. Represents the leakage current phase of each phase, Represents the phase difference of the original two-phase leakage current, Represents the new two-phase leakage current phase difference, i=A, B, C, and establishes the phase difference matrix After aging, the leakage current phase difference matrix becomes Phase difference coefficient Create phase-to-phase differential matrix When not aged, kij = 0, the more serious the aging, the greater kij , and judge the insulation aging of each phase according to the change of the interphase differential matrix [ kij ].
综上，本发明提供一种基于双差动CT法的高压电缆绝缘在线监测装置及方法，包括6个穿心式电流互感器、有源滤波放大器、Zigbee无线通信模块以及计算机；In summary, the present invention provides a high-voltage cable insulation online monitoring device and method based on the double differential CT method, including 6 feed-through current transformers, active filter amplifiers, Zigbee wireless communication modules and computers;
所述6个穿心式电流互感器用于获取电缆电路首/末端A，B，C三相电流差动信号；所述6个穿心式电流互感器中，第一穿心式电流互感器、第二穿心式电流互感器以及第三穿心式电流互感器分别安装在电缆线路首端A，B，C三相电缆终端底部；第一穿心式电流互感器、第二穿心式电流互感器以及第三穿心式电流互感器的二次线圈采用串联方式相连接，采集电缆线路首端A，B，C三相电流差动信号；第四穿心式电流互感器、第五穿心式电流互感器以及第六穿心式电流互感器分别安装在电缆线路末端A，B，C三相电缆终端底部；第四穿心式电流互感器、第五穿心式电流互感器以及第六穿心式电流互感器的二次线圈采用串联方式相连接，采集电缆线路末端A，B，C三相电流差动信号；所述电流互感器均为开合式电流互感器，外壳采用不饱和树脂绝缘；The 6 feed-through current transformers are used to obtain the three-phase current differential signals of the cable circuit head/end A, B, and C; among the 6 feed-through current transformers, the first feed-through current transformer, The second feed-through current transformer and the third feed-through current transformer are respectively installed at the bottom of the three-phase cable terminals A, B, and C at the head end of the cable line; the first feed-through current transformer, the second feed-through current transformer The transformer and the secondary coil of the third through-type current transformer are connected in series to collect the three-phase current differential signals of A, B and C at the head end of the cable line; the fourth through-type current transformer, the fifth through-type current transformer The core-type current transformer and the sixth core-type current transformer are respectively installed at the bottom of the three-phase cable terminals A, B, and C at the end of the cable line; the fourth core-type current transformer, the fifth core-type current transformer and the The secondary coils of the six-through-type current transformers are connected in series to collect the three-phase current differential signals of A, B, and C at the end of the cable line; resin insulation;
通过以上装置本发明能够提取电缆线路绝缘老化后首端电流的差动信号和末端电流的差动信号，与现有电缆在线监测技术相比，能够反映电缆末端负载的变化，同时首末两端差动信号之差构成的二次差动能够有效避免末端负载变化对在线监测结果的影响，准确反映多种电缆线路绝缘老化情况。Through the above device, the present invention can extract the differential signal of the head-end current and the differential signal of the end current after the cable line insulation is aged. Compared with the existing cable online monitoring technology, it can reflect the change of the load at the end of the cable, and at the same time The secondary differential formed by the difference of the dynamic signal can effectively avoid the influence of the terminal load change on the online monitoring results, and accurately reflect the insulation aging of various cables.
以上实施例用以说明而非限制本发明的技术方案。不脱离本发明精神和范围的任何修改或局部替换，均应涵盖在本发明的权利要求范围当中。The above embodiments are used to illustrate rather than limit the technical solution of the present invention. Any modification or partial replacement that does not depart from the spirit and scope of the present invention shall fall within the scope of the claims of the present invention.
Claims (10)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711303073.8A CN108037423A (en) | 2017-12-08 | 2017-12-08 | A kind of high-voltage cable insulating on-Line Monitor Device and method based on double differential CT methods |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711303073.8A CN108037423A (en) | 2017-12-08 | 2017-12-08 | A kind of high-voltage cable insulating on-Line Monitor Device and method based on double differential CT methods |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN108037423A true CN108037423A (en) | 2018-05-15 |
Family
ID=62102143
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201711303073.8A Pending CN108037423A (en) | 2017-12-08 | 2017-12-08 | A kind of high-voltage cable insulating on-Line Monitor Device and method based on double differential CT methods |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108037423A (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108548993A (en) * | 2018-06-08 | 2018-09-18 | 中国人民解放军海军工程设计研究院 | A kind of more cable parallel connection interlinkage fault-line selecting methods |
| CN109521340A (en) * | 2018-12-10 | 2019-03-26 | 珠海许继电气有限公司 | Distribution line insulation detection device and detection method |
| CN110716111A (en) * | 2019-11-13 | 2020-01-21 | 南方电网科学研究院有限责任公司电网技术研究中心 | Ultrahigh-voltage XLPE cable insulation online monitoring device and method based on vector method |
| CN111025093A (en) * | 2019-11-19 | 2020-04-17 | 云南电网有限责任公司临沧供电局 | A method for estimating insulation life of XLPE cable based on double-ended balance factor |
| CN111157915A (en) * | 2019-12-31 | 2020-05-15 | 国网北京市电力公司 | Cable leakage current detection method and device, storage medium and processor |
| CN111679162A (en) * | 2020-06-02 | 2020-09-18 | 国网浙江义乌市供电有限公司 | Insulation monitoring method and device for substation cables |
| CN113109662A (en) * | 2021-03-03 | 2021-07-13 | 中国电力科学研究院有限公司 | Method and system for determining relative aging degree of cable based on interphase relative dielectric loss |
| CN113702787A (en) * | 2021-09-15 | 2021-11-26 | 广东电网有限责任公司 | Method and device for detecting insulated wire of low-voltage line |
| CN115343527A (en) * | 2022-06-27 | 2022-11-15 | 江苏昂内斯电力科技股份有限公司 | A Residual Current Detection Method Based on the Current Vector Relationship of Split Transformer |
| CN117434357A (en) * | 2023-12-20 | 2024-01-23 | 天津航空机电有限公司 | Angular load balance detection circuit |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103698665A (en) * | 2012-09-27 | 2014-04-02 | 通用电气公司 | On-line monitoring of stator insulation in motors and generators |
| CN103947065A (en) * | 2011-11-16 | 2014-07-23 | 维斯塔斯风力系统集团公司 | Protection of a permanent magnet generator |
| CN104852396A (en) * | 2015-05-07 | 2015-08-19 | 陈鸽 | Power load balancing method and device for low-voltage power distribution network |
| CN205562734U (en) * | 2016-04-25 | 2016-09-07 | 国网江苏省电力公司电力科学研究院 | Be used for insulating diagnostic electrified detection and on -line monitoring device of ultrahigh -voltage power cable |
-
2017
- 2017-12-08 CN CN201711303073.8A patent/CN108037423A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103947065A (en) * | 2011-11-16 | 2014-07-23 | 维斯塔斯风力系统集团公司 | Protection of a permanent magnet generator |
| CN103698665A (en) * | 2012-09-27 | 2014-04-02 | 通用电气公司 | On-line monitoring of stator insulation in motors and generators |
| CN104852396A (en) * | 2015-05-07 | 2015-08-19 | 陈鸽 | Power load balancing method and device for low-voltage power distribution network |
| CN205562734U (en) * | 2016-04-25 | 2016-09-07 | 国网江苏省电力公司电力科学研究院 | Be used for insulating diagnostic electrified detection and on -line monitoring device of ultrahigh -voltage power cable |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108548993A (en) * | 2018-06-08 | 2018-09-18 | 中国人民解放军海军工程设计研究院 | A kind of more cable parallel connection interlinkage fault-line selecting methods |
| CN109521340A (en) * | 2018-12-10 | 2019-03-26 | 珠海许继电气有限公司 | Distribution line insulation detection device and detection method |
| CN110716111A (en) * | 2019-11-13 | 2020-01-21 | 南方电网科学研究院有限责任公司电网技术研究中心 | Ultrahigh-voltage XLPE cable insulation online monitoring device and method based on vector method |
| CN111025093A (en) * | 2019-11-19 | 2020-04-17 | 云南电网有限责任公司临沧供电局 | A method for estimating insulation life of XLPE cable based on double-ended balance factor |
| CN111157915A (en) * | 2019-12-31 | 2020-05-15 | 国网北京市电力公司 | Cable leakage current detection method and device, storage medium and processor |
| CN111679162A (en) * | 2020-06-02 | 2020-09-18 | 国网浙江义乌市供电有限公司 | Insulation monitoring method and device for substation cables |
| CN113109662A (en) * | 2021-03-03 | 2021-07-13 | 中国电力科学研究院有限公司 | Method and system for determining relative aging degree of cable based on interphase relative dielectric loss |
| CN113702787A (en) * | 2021-09-15 | 2021-11-26 | 广东电网有限责任公司 | Method and device for detecting insulated wire of low-voltage line |
| CN115343527A (en) * | 2022-06-27 | 2022-11-15 | 江苏昂内斯电力科技股份有限公司 | A Residual Current Detection Method Based on the Current Vector Relationship of Split Transformer |
| CN117434357A (en) * | 2023-12-20 | 2024-01-23 | 天津航空机电有限公司 | Angular load balance detection circuit |
| CN117434357B (en) * | 2023-12-20 | 2024-04-09 | 天津航空机电有限公司 | A Angular Load Balance Detection Circuit |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108037423A (en) | A kind of high-voltage cable insulating on-Line Monitor Device and method based on double differential CT methods | |
| CN101551432B (en) | Power distribution network fault positioning method | |
| CN103308823B (en) | A single-phase disconnection and non-ground fault location method for distribution network | |
| CN106771840A (en) | A kind of dry type hollow reactor interturn short circuit fault online test method | |
| CN106546869A (en) | A kind of hollow power reactor turn-to-turn insulation On-line Fault monitoring device | |
| CN110361686A (en) | Capacitance type potential transformer fault detection method based on multi-parameter | |
| CN101975914A (en) | On-line monitoring method and device for insulating state of power cable | |
| CN108132422A (en) | A kind of monitoring system and method for capacitive reactive power compensation device failure | |
| CN106501696A (en) | A kind of 500kV high-voltage shunt reactors scene local discharge test system and method | |
| CN113671239B (en) | A high-voltage switch PT cabinet overvoltage intelligent identification method, device and system | |
| CN102419408B (en) | System and method for determining single-phase disconnection fault sections based on load monitors | |
| CN202886456U (en) | Capacitor voltage transformer fault monitoring instrument | |
| CN110645888A (en) | A Winding Deformation Judgment Method Based on Frequency Response Analysis FRA | |
| CN207020277U (en) | A kind of converter power transformer discharge characteristic pilot system | |
| CN106443257A (en) | System for monitoring state of EHV (extra-high voltage) transformer based on vibration | |
| CN107797017A (en) | A kind of method of power transformer live detection loss characteristics parameter | |
| CN104237639A (en) | Online monitoring method of insulation state of medium-voltage power cable based on impact impedance characteristic parameter | |
| CN204256059U (en) | A kind of 10kV shunt reactor switching service test system | |
| CN205176158U (en) | Electric capacity type current transformer on -line measuring device | |
| CN202735412U (en) | On-line measurement device for capacitive current of power grid with neutral point grounded through arc suppression coil | |
| CN105203886A (en) | Capacitive type current transformer online detection device and method | |
| CN110716111A (en) | Ultrahigh-voltage XLPE cable insulation online monitoring device and method based on vector method | |
| CN216771825U (en) | Arrester resistive current detection device | |
| CN105223422A (en) | Digital dielectric loss measurement system device and method | |
| CN115792733A (en) | Three-phase transformer fault detection method and system |
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 | ||
| WD01 | Invention patent application deemed withdrawn after publication | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20180515 |