Abstract-A novel transient component bus protection based on mathematical morphology is presented in this paper, which takes the morphological max top-bottomoperator of current traveling wave to fast distinguish the bus internal fault from the external fault. The method is based on the principle that the high frequency component of transient traveling wave caused by bus external fault will be attenuated by the bus capacitance but the traveling wave caused by bus internal fault changes slightly. Simulation is carried out with the electromagnetic transient simulation software PSCAD/EMTDC, the result verifies the bus protection is reliable and accurate. The novel bus protection also can treat lightning failure or lightning disturbance happened on transmission lines as bus external fault, without malfunction.
Traveling wave produced by a short-circuit fault or lightning will propagate along transmission lines with deformation and attenuation, which are due to energy loss and frequency-dependent line parameters. By the phase-modal transform method, the multi-conductor transmission lines could be decoupled into independent modal. Each modal is a single uniform line described as two-port networks. In this paper, the frequency-dependent parameters of uniform transmission lines are calculated in complex frequency domain. Based on the telegraph equation in complex frequency domain, the transfer functions between traveling wave signal source and observation point (relay location) are derived. The time domain waveforms of traveling wave at the observation point are calculated by Hosono numerical Laplace inverse transform method. Compared with PSCAD/EMTDC simulation results, the proposed method in this paper is proved effective.
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