Study on Conducted EMI Based on Wide-Band Model for a ±500 kV MMC-HVDC Station

Abstract

In China, the HVDC technology has been widely applied for the advantage of large capacity as well as high efficiency. The HVDC project adopted modular multi-level converters (MMC) has attracted more and more attention. Zhangbei MMC-HVDC power transmission project is the first four-terminal ±500 kV MMC-HVDC transmission system in the world. The wideband frequency noise is generated during the periodic turn-on and turn-off process of the IGBTs in converter valve. The noise will transmit along the primary circuit in the high voltage switch yard and may interfere with the secondary system, such as the power line communication (PLC) systems, control systems, and so on. A wideband equivalent model of the primary electrical system from the hall of the converter valve to the AC grid was built in this paper. It was to simulate conducted electromagnetic interference (EMI) along the primary high voltage circuit during the steady operation process. Then, the response of the HVDC system influenced by equipment characteristics was described. The Influence of the primary equipment along the propagation route of the EMI was analyzed, and the effect of the PLC filter in the broadband equivalent circuit was discussed. The wideband equivalent model was based on the scheme of Zhangbei ±500 kV MMC-HVDC project and the operating characteristics of the HVDC system. The wideband equivalent model consists of the equivalent circuit model of the major equipment in HVDC system, including converter transformers, reactors, AC filters, PLC filters, and the wiring forms between them. The wideband equivalent model was determined according to measurements of equipment parameters and other HVDC engineering applications considering high frequency characteristic. The excitation source containing EMI derived from the IGBTs was obtained from the test result of the converter valve, which were assembled to form the converter valve used in the Zhangbei project.