Start and quit method of modular multilevel converter (MMC) valve steady-state operation testing device

Abstract

The invention relates to a start and quit method of a modular multilevel converter (MMC) valve steady-state operation testing device. The start and quit method of the MMC valve steady-state operation testing device comprises a start process and a quit process. The start process includes the following steps that (A) a discharging power source charge capacitors in an auxiliary valve and a specimen valve to nominal voltages, and charging return circuits are disconnected; (B) an unlocking controller sends triggering pulses to the auxiliary valve and the specimen valve; and (C) an energy supplementing power source is started to supplement energy which is consumed in a test. The quit process includes the following steps that (I) the supplementing power source is cut off; (II) the triggering pulses of the auxiliary valve and the specimen valve are closed; (III) a grounded rod is sequentially in short-circuit connection with the capacitors of each submoudle to accomplish discharge. The start and quit method of the MMC valve steady-state operation testing device can achieve reasonable coordination among each power source, the supplementing power source and the controller. The fact that the test can be safely and smoothly implemented is guaranteed. Smooth start and safe quit of the MMC valve steady-state operation testing device can be guaranteed.

Description

technical field [0001] The invention relates to the field of high-voltage direct current transmission, in particular to a start-up and exit method of an MMC valve steady-state operation test device. Background technique [0002] Flexible direct current transmission (VSC-HVDC) technology has broad application prospects in the field of high-voltage direct current transmission. VSC-HVDC based on modular multilevel converter (MMC) is a way to realize direct current transmission using IGBT valves , and its core component is called MMC valve. [0003] The purpose of the steady-state operation test of the MMC valve is to investigate the tolerance of the valve assembly to key stresses such as current, voltage and temperature under long-term actual operating conditions, which is also an important part of the research on the reliability of the converter operation. The steady-state operation test device can generate voltage and current stresses equivalent to actual working conditions,...

AI Technical Summary

Problems solved by technology

The method of starting the supplementary power supply first and then putting in the charging power supply when starting up and the method of closing the valve before exiting the supplementary power supply when exiting will cause overvoltage in the capacitor of the grounding sub-module of the auxiliary valve

Due to the particularity of the structure of the MMC valve, the uniqueness of its charging sequence is determined, and the violent exchange of energy after the test starts will cause the loop current to oscillate and lead to overcurrent, which endangers the safety of the IGBT. Therefore, it is necessary to design a suitable soft start method when the device is started.

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