A general analysis method of transmission lines faults response with all frequency components under new energy

Abstract

Nowadays, a large number of photovoltaic power stations have been connected to the grid. As the control algorithm of photovoltaic power generation often uses Maximum Power Point Tracking (MPPT), the electromagnetic transient process generated by frequent regulation process is gathered into the transmission network. And long transmission lines need series compensation which also causes electromagnetic transient process. Since the sampling frequency of the protection device was not high enough in the past, the recorded waveform could not reflect the actual situation. In particular, because some high-frequency harmonics could not be observed, the harm brought by them did not attract enough attention, and the adverse effects gradually increased. In this paper, the transient response of faults in transmission lines can be accurately calculated by a method, which combined with the phase component method and the Laplace transform. According to the topological relationship of transmission lines, a frequency domain model considering the initial energy storage is given. Whether the system parameters are symmetrical or not, the model can accurately calculate the transient response. Besides, various faults are described by modifying the node admittance matrix. And the system response that includes all frequency components in the time domain are obtained by the inverse Laplace transform. In the case of a simple transmission system, the calculation results are compared with those obtained with the ATP/EMTP. Such comparisons validate the effectiveness and accuracy of the method. The method can accurately reflect all transient components at different frequencies caused by faults or disturbances, and it is suitable for both transient studies and steady-state analysis.