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Xue A.,North China Electrical Power University | Luo L.,North China Electrical Power University | Jing Q.,North China Electrical Power University | Cao X.,China Southern Power Grid Guangzhou EHV Bureau | And 2 more authors.
Dianwang Jishu/Power System Technology | Year: 2014

It is of significance for the assessment on protective relayings to evaluate possible consequences caused by being operated protective relayings. Combining with the state of transmission lines and the failure mechanism of protective devices, a risk assessment method of protective relayings for high-voltage transmission lines is proposed. Firstly, ten states of overall system composed of transmission lines and protective devices are given and further according to the property of self-checking of microcomputer-based protective devices, four kinds of risks, namely the detected unready operation failure, the undetected unready operation failure, the detected unnecessary operation failure and the undetected unnecessary operation failure, are concluded. Secondly, according to the division of the states of transmission lines and protective devices, a 10-state Markov model is established, and using this Markov model a computing method for above-mentioned four kinds of risk indices is given. Finally, based on the measured failure data of protective devices in a certain power system, the differences in evaluating reliability by the proposed risk indices and traditional reliability indices are compared, and the impacts of self-checking rate on risks are analyzed. Analysis results show that there are obvious differences of both risk indices and unavailability that change with the cycle of periodical survey; the risk indices and unavailability of the system can be effectively reduced by decreasing the failure rate or increasing the self-checking rate. Source


Xue A.,North China Electrical Power University | Wang B.,North China Electrical Power University | Wang R.,North China Electrical Power University | Cao X.,China Southern Power Grid Guangzhou EHV Bureau | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

The time-varying aging failure rate (AFR) can simulate the failure characteristic of protection devices more accurately than the mean failure rate (MFR). This paper focuses on the time-varying failure rate (TFR) characteristics for the HVDC protection devices and firstly divides the failure data into two catalogs, i.e. the aging failure and random failure. Next, with the above data, the time-varying aging failure rate (AFR) is estimated with the Weibull distribution function, and the constant random failure rate (RFR) is drown up with estimating exponential distribution function; then TFR is obtained with the addition of AFR and RFR. Furthermore, based on the field failure data of a regional power grid, TFR of the grid can be obtained and the differences in time-varying failure characteristic of different batches and modules of protection devices are given. Results show that different batches of the devices are, respectively, in the loss failure period and the random failure period, thus the maintenance strategy should be formulated severally. Meanwhile, results also indicate that power and communication unit is easy to enter the loss failure period. © 2012 State Grid Electric Power Research Institute Press. Source


Liang J.,China Southern Power Grid Guangzhou EHV Bureau | Yu H.,China Southern Power Grid Guangzhou EHV Bureau | Yu H.,Guangdong Key Laboratory of Clean Energy Technology | Yang P.,Guangdong Key Laboratory of Clean Energy Technology | And 3 more authors.
Gaoya Dianqi/High Voltage Apparatus | Year: 2015

To fully understand failure mechanisms of the valve base electronics (VBE) for its fault diagnosis and maintenance, we analyzed the hardware components of VBE, obtained its key signals and data stream, and designed a comprehensive test platform. The platform consists of a simulation platform for actual converter valve, a minimum VBE system for controlling and monitoring the converter valve simulation platform, and a monitoring platform based on Labview. The comprehensive platform can simulate normal working status and fault conditions of VBE system, and display key signals of VBE system under fault conditions to capture and analyze the fault signal features for maintenance. ©, 2014, Xi'an High Voltage Apparatus Research Institute. All right reserved. Source


Xue A.,North China Electrical Power University | Luo L.,North China Electrical Power University | Jing Q.,North China Electrical Power University | Lin R.,China Southern Power Grid Guangzhou EHV Bureau | And 4 more authors.
Chinese Control Conference, CCC | Year: 2014

It is a significant problem to evaluate the running protective relay devices. This paper proposes a novel risk evaluation method for HV line protection. Firstly, six states of the system are established. Considering the self-check of the protective relay, four risk indexes are derived. Then, according to the state division of the system, ten state Markov model is established and then the risk and unavailability indexes of the system can be calculated. Finally, based on some real grid data, the unavailability and risk indexes is analyzed under different maintenance cycles, failure-rates and self-check rates. The conclusion is drawn: the risk and unavailability has different changing trend with the maintenance cycle increasing; a smaller failure rate or a larger self-check rate can keep risk and unavailability at a lower level. © 2014 TCCT, CAA. Source

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