Abstract: A new frequency-dependent network equivalent method based on Gaussian elimination is presented in the paper. In the method, the external system's frequency admittance matrix, that is actually the transfer function of external system, is directly calculated by Gaussian elimination method, and the equivalent network is obtained by corresponding relationship between simple RLC branch and fraction gained through the operation of the transfer function. In view of the high complication and huge computation of the equivalent network caused by large-scale power system, a simplification strategy and a step-by-step solution method are further proposed in the paper respectively for the equivalent network and for the large-scale network, which successfully realize the equivalence of a large system. Since the transfer function of external network includes all the electrical information of the external system in a wider frequency range, the equivalent electric circuit of the external system network obtained by the proposed frequency-dependent network equivalent method can reflect the electrical characteristics in a relatively large frequency range with high equivalent precision. Case study has validated the effectiveness of the method.

Key words: power system network, frequency-dependent equivalent, Gaussian elimination, step-by-step solution