IGBT overcurrent turn-off tests for the MMC-based VSC valves

Nowadays, the Multi-level Modular Converter (MMC) has shown more and more advantages over the traditional Pulse Width Modulation (PWM)-based converter and has been widely adopted as the preferred topology for VSC (Voltage Sourced Converter) valves for High Voltage Direct Current (HVDC). Though IEC 62501 has been published since 2009 to define the requirements of the electrical testing for the VSC valves, so far very few papers have really discussed the test methods for any VSC valve tests or disclosed any test results. In this paper, one of the most important tests required by IEC 62501, the IGBT Overcurrent Turn-off test, is discussed for MMC-based VSC valves. Several faults that may occur when the IGBT can experience overcurrent are analysed, the test methods for several supplementary tests are discussed and finally the relevant test results are presented.