Input‐voltage and output‐current equalization of series‐in parallel‐out three‐phase multi‐module voltage source converter‐based high voltage direct current shunt tap

摘要

Abstract Conventionally, high voltage direct current (HVDC) shunt taps are used to feed a three‐phase local network by employing a DC‐AC 2‐Level voltage source converter (2L‐VSC), where its DC side is connected to the DC‐link voltage, while its AC side is fed to a step‐down transformer to meet the local network voltage level. To meet the high‐voltage ratings of the 2L‐VSC, series‐connected Insulated‐Gate Bipolar Transistors (IGBTs) should be employed with proper static and dynamic voltage sharing of the involved IGBTs per each valve. To avoid the complexity and challenges of series‐connected devices, an alternative solution for HVDC shunt tap is proposed in this paper, where DC‐AC inverter based on series‐input parallel‐output multi‐module 2L‐VSCs with input‐voltages and output‐currents equalization is employed, which enables employing of IGBTs with relatively medium‐voltage rating. In the proposed architecture, the AC sides of VSCs are fed to step‐down transformers, where the transformers' secondary sides are connected in parallel for current sharing purpose. Simulation results for normal as well as abnormal operating condition are presented to show the dynamic performance of the proposed architecture and validate the presented voltage and currents equalization techniques. The proposed architecture is also compared with the other existing options to show the effectiveness of the suggested approach.