Analysis Of Electromagnetic Interference For SMES Voltage Source Converter

With the rapid development of economy in our country, the demand of electricity is increasing. At the same time, the complexity and the scale of power system increase rapidly, the diversification and complexity of power grid bring great challenge to the stability of power system. Compared with the traditional and passive way of making the power system stable, the energy storage technology is more active and flexible. Superconducting Magnetic Energy Storage(SMES) is able to store electrical energy efficiently, combined with the well-studied power electronic technology and control technology, it can detect the change of power timely and accurately, and make power compensation quickly when the power fluctuates, and finally make the power system stable actively near the fault point. SMES has some characteristics as follows: lossless storage, millisecond response rate, simple maintenance, low pollution, and longer life and so on, compared with other energy storage methods, the SMES has obvious advantages.Because of the good performance of the converter, SMES has the characteristic of millisecond response speed. Full controlled power electronic switching devices are used in the converter, which can improve the dynamic response speed of the energy storage system,and control active power and reactive power independently and quickly in the four-quadrant. Because the high-speed switching action of power electronic switching devices will produce a high voltage change rate dv/dt and current rate di/dt, and meanwhile, parasitic parameters exist in all the devices in the circuit, all these factors will cause serious electromagnetic interference, when the circuit is working, which would threaten the safe and stable operation of the energy storage system and affect the normal operation of the surrounding equipment. Therefore, it is necessary to study the electromagnetic interference about SMES converter.This dissertation mainly aimed to analyze the electromagnetic interference produced by the SMES voltage source converter. Firstly, the working principle and structure of SMES are introduced. The research status and development of the electromagnetic interference of SMES converter system are summarized.Secondly, the conduction mechanism of electromagnetic interference and interference propagation path are obtained, and the high frequency model of the converter is established by analyzing the working process of SMES voltage source converter. The conducted electromagnetic interference of SMES voltage source converter is simulated and compared under the ideal and high frequency condition of device by the Matlab software.Finally, the radiation electromagnetic interference of the voltage source converter of SMES is studied, including the interference of superconducting magnet stray magnetic field with rectifier cabinet and the near field radiation of converter inside the rectifier cabinet. Comparing and analyzing the shielding effect with different closed situation of cabinet for superconduc- ting magnet stray magnetic field, the near field radiation of main circuit parts of converter is simiulated by Ansoft HFSS software, which includes the AC line, heat sink of switch and the current circuit.