Direct-current overvoltage current limiting control method of flexible HVDC convertor station

Abstract

The invention provides a direct-current overvoltage current limiting control method of a flexible HVDC convertor station. The method can solve the problems that when alternating-current side grid faults of a flexible HVDC system receiving end convertor station or direct-current monopole disconnection faults of a sending end convertor station happen, power output of the sending end convertor station is limited so that direct-current bus overvoltage is caused, and when the voltage exceeds a protection setting value, a flexible HVDC system is locked and shut down, and the method can be used for quickly lowering the absorbed active power value of the sending end convertor station from an alternating-current power grid and restraining direct-current circuit voltage rise. When the method is applied to flexible HVDC system control, and power grid faults cause the problems that the convertor station power transmitting capacity is limited and direct-current voltage quickly rises, the absorbed active power of the sending end convertor station from the alternating-current power grid is lowered, direct-current voltage rise is restrained, and the problem that the flexible HVDC system is locked and shut down due to the fact that the voltage exceeds the protection setting value is avoided.

Description

[0001] technical field [0002] The invention belongs to the technical field of grid stability control of electric power systems, and in particular relates to a DC overvoltage current limiting control method of a flexible DC transmission converter station. Background technique [0003] When the AC-side power grid or the DC-side single-circuit line of the converter station fails and the voltage drops, the output active power of the DC side will decrease, and the energy will be continuously stored in the capacitors connected in parallel between the DC buses, resulting in the rise of the DC bus voltage and the failure of the AC side. If the current is too large, if it is not dealt with in time, it will trigger the control and protection action of the converter, shut down the entire converter station, and even the entire flexible DC transmission system. This has the following disadvantages: 1) It increases the outage probability of the HVDC system; 2) If the operating converter...

AI Technical Summary

Problems solved by technology

[0003]When the AC side power grid or the DC side single circuit line of the converter station fails and the voltage drops, the output active power of the DC side will decrease, and the energy will be continuously stored in the parallel On the capacitors between the DC bus bars, the voltage of the DC bus bar will rise and the current on the AC side will be too large. If it is not handled in time, it will trigger the control and protection action of the converter, shut down the entire converter station, and even the entire flexible DC transmission system

This has the following disadvantages: 1) It increases the outage probability of the HVDC system; 2) If the operating converter station or the operating system is connected to important loads, the outage of the converter station will cause heavy losses; 3) If two If the non-synchronous power grid is connected to the network through the flexible direct current transmission system, the shutdown of the converter station will cause the two non-synchronous power grids to split, the power grid stability control and protection action will lose part of the power supply or load, and even lead to cascading failures, resulting in the paralysis of the synchronous power grid; 4 ) If the converter station is shut down, it may lead to the overload of its parallel AC line, and even the power flow of the line exceeds its temporary stability limit, resulting in the grid stability control and protection action; 5) The restart of the converter station or even the entire system is complicated

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