带并补电抗器超/特高压输电线路单相瞬时故障拍频特性研究

Beat-frequency characteristics for single-phase transient fault of EHV / UHV transmission line with shunt reactor

以带并联电抗器补偿的线路为研究对象,深入剖析了单相瞬时故障消失后产生拍频现象的机理和条件,探讨了瞬时故障低频自振分量的频率及幅值衰减特性,以及断开相电气量无显著拍频现象产生的条件。研究结果表明:故障电气量中产生明显拍频现象的条件为瞬时故障且电弧可靠熄灭,但部分瞬时故障由于工频和低频量幅值差过大、频差过小或低频自振分量幅值衰减过快,导致断开相电压与电抗器电流没有明显拍频现象,此时可采用非拍频特征判据实现故障性质识别。大量ATP仿真与物理实验模型仿真验证了上述理论分析的正确性。

The beat-frequency phenomena may occur after the single-phase transient fault of transmission hne with shunt reactor is disappeared,the mechanism and conditions of which are deeply analyzed. The frequency and attenuation characteristics of low-frequency free oscillation component of transient fault and the conditions,under which no obvious beat-frequency phenomena will occur after the faulty phase are de- energized,are discussed. Results show that,the obvious beat-frequency phenomena will occur in faulty electrical variables only when the fault is transient and the arc is reliably extinguished. For some transient faults,if the difference between elementary- and low-frequency components is too big in amplitude and too small in frequency,or the low-frequency free oscillation component is quickly attenuated,no beat-frequency phenomena will occur in the voltage of tripped phase and the current of reactor,where the fault type can be identified by non-beat-frequency criteria. Simulative results of ATP and physical experiment model verify the correctness of theoretical analysis.