Method And Application Of Single-Pole Adaptive Reclosure In Transmission Lines

It is critical for single-pole adaptive reclosure to distinguish fault type and detect the secondary arc extinction time. The technology of distinguishing fault type can avoid the circuit breaker reclosing when permanent fault occurs, thus, it can protect the power system from second impact. The technology of detecting the secondary arc extinction time can avoid the circuit breaker reclosing when transient fault arc burning, thus, it can ensure the circuit breaker to reclose successfully. By studying the method of fault identification and extinguishing time capture in transmission lines, two criterions of adaptive single-phase adaptive reclosure are proposed:one based on improved adaptive cumulative sum method (ACUSUM) and the other based on high order harmonic.First of all, background and research status of single-pole adaptive reclosure is introduced. Meanwhile, the characteristics of arc, the characteristics of recovery voltage and the secondary arc current in transmission lines are analyzed. Methods of accelerating the secondary arc extinguishing are discussed. In view of the transmission lines without shunt reactor and with shunt reactor, the transient fault and permanent fault arc models are built by software ATP-EMTP. Then obtain the simulation waveform of the fault phase voltage.Secondly, according to the pattern of fault phase voltage amplitude varies in different fault conditions, the method for fault recognition and secondary arc extinct time capture is proposed by detecting the change of voltage amplitude. Method of adaptive reclosure based on improved ACUSUM criterion is proposed. Detection of voltage amplitude changes mainly rely on improved adaptive cumulative sum method algorithm (Adaptive Cumulative Sum Method, ACUSUM). ACUSUM algorithm overcomes the shortage of the original ACUSUM, which has a large amount of computation and short duration of the trigger signal. The scheme of adaptive reclosure based on improved ACUSUM algorithm can distinguish the fault characteristics and capture the arc extinguish time at the same time. This method is easy to realize with strong anti-interference ability, and is suitable for transmission lines with or without shunt reactors. The feasibility of the adaptive reclosure method is verified by simulation.Thirdly, by analyzing the variation of harmonic and inter harmonic of fault phase voltage before or after transient fault arc extinct, a method to capture fault arc extinction time based on high order harmonic distortion rate is proposed. This method is easy to realize, not affected by the pollution of grid integer harmonics, and can be applied to the transmission lines with or without shunt reactor. The feasibility and effectiveness of the proposed method is verified by ATP-EMTP simulation results in diffident transition resistance and diffident fault location.Lastly, the improved ACUSUM criterion and the high order harmonic criterion is used in the optimal auto switching device and adaptive reclosing scheme is established.