Converter overvoltage protection system and parameter design method of unified power flow controller

Abstract

The invention discloses a converter overvoltage protection system and a parameter design method of a unified power flow controller. The system includes first to third arresters, a thyristor bypass switch, a bypass circuit breaker and a monitoring device, wherein the second arrester One end is grounded through the first surge arrester, the other end is connected to the connection line between the converter valve and the bridge arm reactor, and the thyristor bypass switch is connected in parallel with the second surge arrester; the third surge arrester is connected in parallel with the connecting copper bar, using a star connection, And its neutral point is connected to the neutral point of the series transformer and grounded through the grounding resistance; the bypass circuit breaker is connected in parallel to the line side of the series transformer; the monitoring module is used to monitor the status of the converter valve, thyristor bypass switch and bypass circuit breaker Monitoring and control, when the converter valve is detected to be blocked, the bypass thyristor is controlled to be turned on, and the bypass circuit breaker is closed at the same time. This technical solution can effectively reduce the overvoltage protection level of the converter, and greatly improve the economy and reliability of the converter.

Description

technical field [0001] The invention belongs to the field of flexible AC power transmission, and particularly relates to a converter overvoltage protection system for a unified power flow controller and a parameter design method thereof. Background technique [0002] The modern power system has gradually evolved into a large-scale AC-DC hybrid power grid. The problems of unbalanced distribution of load and power generation within the power grid and large differences in the distribution of power flow in transmission channels have become increasingly prominent. The problems of heavy and light loads in transmission channels exist simultaneously. Limited by the bearing capacity of the heavy-duty channel, it is difficult to use the transmission channel in the power grid very effectively. At the same time, due to the restrictions of urban planning, the difficulty of line reconstruction and power grid expansion is increasing, and the reliable and economical operation of the transmi...

AI Technical Summary

Problems solved by technology

[0004] The existing overvoltage protection method for the converter of the unified power flow controller is to use a gapless zinc oxide arrester connected in parallel on the AC side of the converter and on the valve side of the series transformer, and the arrester connected in parallel on the valve side of the series transformer is also connected in parallel with a fast bypass switch , this protection method usually uses the voltage and current nonlinear characteristics of the zinc oxide arrester to limit the voltage between the converter valve terminals caused by the fault of the AC system, but the parameters of the gapless zinc oxide arrester in this method are controlled by the unified power flow. In the case of a DC side fault, The limitation of the overcurrent of the inverter and the high level of overvoltage protection of the arrester lead to a great increase in the manufacturing difficulty and cost of the inverter

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