Hybrid phase shift control strategy applicable to LCC DC power transmission system inverter side AC fault

Abstract

The invention discloses a hybrid phase shift control strategy applicable to LCC DC power transmission system inverter side AC fault. The strategy includes phase shift control which is based on rate of rise and transient value of a DC current and phase shift control which is based on mean square root and degree of asymmetry of an AC voltage. The phase shift control which is based on rate of rise and transient value of a DC current is intended for initial action of an inverter side AC fault so as to circumvent failure of phase shift or shorten the time length of the failure of phase shift if phase shift fails. The phase shift control which is based on mean square root and degree of asymmetry of an AC voltage is intended for system recovery action in the middle and later stage of an inverter AC fault and when the fault is resolved in order to optimize system recovery features. Therefore, the strategy herein can effectively address the failure of phase shift caused by inverter side AC fault of the system.

Description

technical field [0001] The invention belongs to the technical field of power system control, and in particular relates to a composite phase-shifting control strategy applicable to an AC fault on an inverter side of an LCC (Line Commuted Convertor) direct current transmission system. Background technique [0002] HVDC power transmission has important applications in my country's west-to-east power transmission and asynchronous networking. However, the HVDC transmission system is prone to commutation failure under the AC fault on the inverter side, resulting in a decrease in the DC voltage, an increase in the DC current, a drop in the transmission power, and an adverse impact on the service life of the converter valve; if the recovery process Improper control and continuous commutation failure will further aggravate the impact on the AC power grid at the receiving end. In recent years, with the continuous improvement of the voltage level and transmission power of new HVDC tra...

AI Technical Summary

Problems solved by technology

The action speed of the constant turn-off angle control mode depends on the proportional coefficient and integral time constant in the proportional-integral regulator; under the parameter conditions commonly used in current high-voltage direct current transmission projects, the trigger angle of the inverter side is reduced from the normal value to the minimum allowable value It usually takes tens of milliseconds, which is much longer than the time required for commutation failure to occur, making commutation failure unavoidable

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