Electromagnetic Transient Simulation Method Of Power System Based On Diakoptics

Electromagnetic transient simulation is used to analyze the transient voltage and current of power system caused by operation or fault, provides experimental data for the research of the dynamic behavior. With the growing scale of grid, the structure becomes more and more complex, which puts forward higher requirement to electromagnetic transient simulation technology, so it has the theoretical and engineering application value to study the electromagnetic transient simulation method.This paper is based on diakoptics, proposes a fast transient simulation method of the transformer. Transformer distributed parameter model is substituted by multistage RLC cascade circuit model. To reduce the simulation calculation and improve the efficiency, equivalent circuit model is established to fast transient process simulation for the transformer, based on the multistage RLC cascade circuit model. In an interval time, put several cascade circuits as a sub-circuit, and deduce its equivalent model, transformer equivalent model is established by suturing the equivalent circuit models of all the sub-circuits together. Making numbers properly to the nodes of model, transformer equivalent model can be described by tridiagonal equation, which is solved by chase method. Using the proposed method, the example studies the fast transient process of transformer struck by the lightning wave. Compared with Simulink results, the proposed method has higher accuracy and efficiency. The paper provides an effective method for fast transient process simulation of transformer.When analyzing the electromagnetic transient of power system, because the structure of generator and network elements are complex, differential equation of system has higher order, it is more difficult to model the system directly, and has larger amount of calculation. In the paper, the system is divided into several sub-systems, and then the equivalent model of each sub-system is established. This paper proposes equivalent model of the generator and network (line, transformer and load) elements in dq0 and abc coordinate system. The model can be equivalent with original sub-system in an interval time instead of in an integral step. Simulation results illustrate that it can improve the efficiency of the simulation. The proposed model is simple in structure, has less variable, is easy to program, modify, and maintenance. To solve the problem of rigid system, generator is divided into fast system and slow system. The fast system reflects the changing process of electromagnetic variable, and slow system reflects the changing process of mechanical variable. Choose lesser integral step to fast system, but choose larger integral step to slow system.The proposed method and models of generator, line and transformer are used to simulate in simple system. Through the simulation test, it analyses the influence of simulation efficiency in different split times. In the same accuracy, selecting the reasonable split times can effectively improve the efficiency of electromagnetic transient simulation. The simulation results illustrate that the proposed method models are correct and effective.