A realization method of mmc redundancy protection strategy based on carrier phase shift modulation

Abstract

The invention provides a method for realizing an MMC redundancy protection strategy based on carrier phase shift modulation, which comprises the following steps: firstly, the state of a sub-module is divided into the normal operation state and redundant standby state according to bypass switch state of the MMC sub-module; then the start-up mode of precharging the redundant sub-module is adopted, and a corresponding carrier dynamic allocator is designed to solve the problem that when a sub-module in the state of normal operation fails, carrier assignment problem exists during the operation of a redundant standby sub-module; finally in full consideration of the influence on capacitance pressure balancing and circulation inhibition strategies when the redundant standby sub-module is put into operation, a trigger with the redundancy protection function is designed; the designed redundancy protection strategy can improve the reliability of operation of the system, ensures that the current converter can continuously perform normal operation when the sub-module fails, the purpose that the failure sub-module is replaced with the redundant sub-module can be realized quickly at the same time, and obvious perturbation of the system can not be caused.

Description

technical field [0001] The invention belongs to the technical field of power system operation and control, and relates to an implementation method of an MMC redundancy protection strategy based on carrier phase-shift modulation. Background technique [0002] With the development of high-power power electronic devices, the voltage source converter (Voltage Source Converter, VSC) based on IGBT and other fully-controlled power electronic devices and pulse-width modulation (Pulse-width Modulation, PWM) technology has become the development of DC transmission. new trend. The High Voltage Direct Current (HVDC) system based on the voltage source converter is widely used in large-scale wind farm grid-connected, distributed generation grid-connected, island power supply, asynchronous AC It has been widely used in grid interconnection and multi-terminal direct current transmission. [0003] However, conventional VSC-HVDC systems generally use two-level or three-level voltage source ...

AI Technical Summary

Problems solved by technology

However, the CPS-SPWM method generates a trigger signal by comparing the carrier wave corresponding to each sub-module with the modulation wave, and does not perform capacitance sorting. Therefore, CPS-SPWM cannot easily implement a redundant protection strategy for sub-modules like the recent level modulation method. It is one of the main problems encountered by CPS-SPWM at present

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