Huang C.,Hunan University |
Yang S.,Hunan University |
Yang S.,Hunan Electrical Examine and Repair Company |
Liang Y.,Hunan Electrical Examine and Repair Company |
And 4 more authors.
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2014
Because the fault records occupy only a small proportion of the whole record file, a channel-specific and segment-specific data compression method is proposed for the mass data transmission of power system fault records. Because the FFT(Fast Fourier Transform) algorithm has higher data compression ratio for periodic signals, the segment data are treated by FFT algorithm first. If the error is bigger, the wavelet transform is then applied. If the frequency offset of power system is greater than the rated value, the windowed Fourier transform algorithm with frequency calibration is applied to ensure the compression ratio and compression precision. Simulation and actual compression of record file show that the proposed algorithm has better compression performance and smaller error, verifying its feasibility and validity.
Luo X.,Hunan University |
Huang C.,Hunan University |
Pan Z.,Hunan Electrical Examine and Repair Company |
Liu K.,Hunan Electrical Examine and Repair Company |
Liang Y.,Hunan Electrical Examine and Repair Company
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2016
This paper proposed an method for single-phase adaptive resclosure based on the reactive power of sequence components for extra high voltage (EHV) transmission lines without shunt reactors. After circuit breaker tripping the fault phase line, for the permanent fault, the voltages and currents of the fault line rapidly get into the steady state, and the reactive power of sequences components becomes almost a constant. However, in the secondary arc stage of transient fault, affected by the arc elongation, the arc voltage and the fault phase voltage increase. Therefore the positive sequence and negative sequence components of the reactive power continue to vary on the contrary way. According to this phenomenon, The rate of variation of positive sequence and negative sequence reactive power components at the faulted line side is used to distinguish fault nature. In the moment of arc extinction, the angle of the faulted phase voltage lags 90°, and then the positive sequence and negative sequence reactive powers have different polarity transitions. According to these phenomena, a new approach based on the reactive power of sequence components is used to identify the fault nature and capture the arc extinction time of the transient fault. The method is simple, hardly influenced by fault resistance and fault distance, and can be utilized in heavy load lines. EMTP simulations have verified its correctness and effectiveness. © 2016, The editorial office of Transaction of China Electrotechnical Society. All right reserved.