The Research of Electromagnetic Transient Simulation Method Based on Discrete Similarity

Under the background of a large number of power electronic devices connected to the power system, the traditional simulation methods have encountered great challenges. The trapezoidal algorithm widely used in EMTP cannot effectively suppress numerical oscillations when the circuit topology changes. Other improved methods had some problems in complex implementation and calculation. In order to solve the above problems, this paper proposed a simulation method based on discrete similarity from the discrete nature of simulation. This method constructed discrete system similar to continuous system in the frequency domain using pole-zero response matching, which is different with the traditional simulation that the differentiation is directly made in the time domain. And then inversed transformation of discrete system in the frequency domain to obtain difference equation. Starting from the causes of numerical oscillations, combined components capable of effectively suppressing numerical oscillation was obtained through analysis and comparison. For independent inductor and capacitor that cannot be directly differentiated by using pole-zero response matching, they are solved by series and parallel positive and negative virtual resistors respectively, thereby ensuring the method can has global consistency for different components or branches. Finally, the validity of the method was verified by examples. © 2020 Chin. Soc. for Elec. Eng.