Research Of Traveling Wave Time Difference Based Powe Network Fault Location And Wide-area Traveling Wave Protection Method

With the constant enlargement of power system capacitance, the structure of network is increasingly complicated. The power system puts forward higher demand for the accuracy of fault location and snap action of relay protection, therefore the fault location and protection method based on the traveling information of single line in transmission network is unable to meet the demand of power network operation. The fault location and protection system based on the whole network initial traveling wave information has strong fault-tolerant ability. The system can fully apply any of fault path including fault line to achieve accurate fault location, meanwhile the polarity of effective initial traveling wave and arrival time can realize line protection, which can improve the accuracy and reliability of protection operation, and enhance the accuracy, reliability and adaptability of traveling wave fault location.In this paper, according to the existing problems of traveling wave fault location and protection, the extraction and detection of traveling wave is further studied. By deep analysis the fault location network and transmission characteristic of traveling wave, a simplified method of traveling wave measurement network is proposed in the thesis. On the basis, traveling wave fault location technology and wide-area traveling wave protection technology are conducted thorough research. A Series of technology, which possessing intellectual property are formed in this paper. The main research contents and innovation of the thesis are as follows:(1) From the single-phase transformer distributed parameter model, the transient traveling wave transfer characteristics of the voltage transformer is further studied, furthermore transient traveling wave extraction methods are proposed in the thesis, such as extracting directly through the voltage transformer secondary side, using the special traveling wave sensor to extract from the CVT grounding line and transformer outside shell grounding line, and using the PCB traveling wave sensor extracted by high voltage directly etc.. So many transient signal extraction methods to provide a wide range of options for obtain the traveling wave in the power failures. The above methods laid solid technical foundation for traveling wave fault location and the wide-area protection.(2) Based on the analysis of chock error, making full use of the complementary characteristic of the random error of GPS synchronous clock and the accumulative error of high-precision crystal oscillator, a high-precision clock synchronization based on the digital phase-locked principal is presented. By measuring the phase difference between GPS second-pulse and crystal oscillator second-clock to control the frequency multiplier coefficient of crystal oscillator second-clock, the new method can real-time eliminate the accumulative error of high-precision crystal oscillator, thus producing the high-precision clock synchronization. Testing results show that the high-precision clock synchronization has high stability, synchronization and precision.(3) The thesis, which makes a systematic analysis of traveling wave transmission characteristics in power girds and the main impact factors of traveling wave transmitting along the line, constructs traveling wave fault location network used topology graph to describe. A simplified method of topology graph based on initial traveling wave transmission network is proposed. Based on network structure and fault position, combined with Floyd algorithm and initial traveling wave arrival times recorded by all substations in network, invalid path can be dynamic eliminated. The multi-loop network can be easily simplified into radial network, which is the initial traveling wave transmission path network. The implementation of traveling wave fault location technology becomes possible.(4) A traveling wave fault location method based on the initial valid traveling wave arrival time is proposed in this paper, which the initial traveling wave arrival time and line length are applied to distinguish valid initial traveling wave arrival time. On this basis, a optimal configuration method of traveling wave fault locators are researched, and a optimal configuration principle and a optimization method based on simulated annealing algorithm is proposed. Simulating and practical application results show that the method can implement the accurate fault location, even in the case of locate devices failure, start up failure or time record error. Moreover, optimal configuration method of traveling wave fault locators can save investment effectively.(5) The conception of wide-area traveling-wave is proposed in the thesis. By analysis the initial traveling wave arrival time and polarity characteristics, two types of wide-area protection is proposed in this paper, one is based on polarity comparison principle, and the other is based on the time characteristic principle. To thorough study the implementation principle, protection criterion and application scope of two types of wide-area protection, a though of comprehensive utilization the two types of wide-area protection in extreme condition is obtained. Theory analysis and simulation results show that the wide-area protection is feasible, simple and has high reliability, which is help to improve the practicality of traveling wave protection. Theory study, simulation analysis, experimental testing and field operation show that the network-based traveling wave fault location technology and wide-area traveling-wave protection technology have an extremely bright future.