【摘要】 当电压过零点附近发生故障时行波信号十分微弱,并且叠加在强大的工频量信号上,再加上各种干扰因素,实际中行波保护不能正确检测到行波波头,可能导致保护拒动或误动。文章对电压过零点附近故障与非电压过零点附近故障进行了大量的电磁暂态仿真,结果表明,电压过零点附近故障时电流行波的低尺度小波变换波形绝大部分远离时间轴,而非电压过零点附近故障时电流行波的低尺度小波变换波形绝大部分靠近时间轴。并根据这一特征提出了一种检测电压过零点附近故障的方法,仿真试验表明该方法可靠、有效。更多还原

【Abstract】 When faults near zero-cross point of voltage occur, the travelling wave signals are very weak and superposed on strong power frequency signal, in addition taking account of various interference factors it is actually very difficult for travelling wave based protection to correctly detect the wavefront, so the miss operation or maloperation may be caused. A lot of electromagnetic simulations for faults near zero-cross point of voltage and far from zero-cross point of voltage are performed, simulation results show that for faults near zero-cross point of voltage the most majority of waveforms of low scale wavelet transform of current travelling wave are far from time axis, and for faults far from zero-cross point of voltage the most majority of waveforms of low scale wavelet transform of current travelling wave are close to time axis. Based on this feature an approach to detect faults near zero-cross point of voltage is proposed and many simulation results show that the proposed approach is reliable and effective.更多还原