Low wear-through control method of doubly-fed wind turbines in sending-end power grid based on DC commutation failure identification

Abstract

The invention discloses a low ride-through control method for a doubly-fed wind turbine of a transmitting-end power grid based on DC commutation failure identification, which comprises the steps thatthe real-time terminal voltage of a doubly-fed wind turbine generator set is detected, and the critical terminal voltage when LCC-HVDC (Line Commutation Converter High Voltage Direct Current) fails incommutation is calculated; if the terminal voltage drops to the vicinity of the critical terminal voltage, the doubly0-fed wind turbine generator set remains unchanged in control mode and waits for acommunication signal of an LCC-HVDC inversion station, whether reactive power control is started or not is determined according to whether the LCC-HVDC inversion station fails in commutation or not;and if the LCC-HVDC inversion station does not fail in commutation, the doubly-fed wind turbine generator set starts the reactive power control, otherwise, the doubly-fed wind turbine generator set always remains the steady-state control strategy until the high voltage ride-through control is started. The method can enable a control system of the doubly-fed wind turbine generator set to automatically distinguish the failure commutation of the LCC-HVDC inversion station and the fault of the transmitting-end power grid and adopt different control modes, and alleviates the rise of terminal voltage of the doubly-fed wind turbine generator set of the transmitting-end power grid under the failure commutation of the LCC-HVDC inversion station and the high voltage off-grid problem of the set as far as possible under the premise of meeting the low ride-through standard of wind power to the greatest extent.

Description

technical field [0001] The invention relates to the field of power system protection and control, in particular to a low-breakthrough control method for a doubly-fed fan in a sending-end power grid based on DC commutation failure identification. Background technique [0002] The shortage of fossil energy and the pressure of environmental protection have promoted the development of new energy sources such as wind power. It is an economical and efficient solution to transmit wind power to a remote load center using a high-voltage DC transmission system (Line Commutation Converter High Voltage DirectCurrent, LCC-HVDC) with grid commutation converters. Since LCC-HVDC uses semi-controlled devices as switching elements, commutation failure may occur in its inverter station when the AC power grid at the receiving end fails. After the commutation failure occurs, the reactive power absorbed by the rectifier station increases first and then decreases, which leads to the AC bus voltag...

AI Technical Summary

Problems solved by technology

When LCC-HVDC commutation fails, it will also cause the terminal voltage drop of the doubly-fed wind turbine. The degree of drop is obvious but the duration is short. The degree of overvoltage in the subsequent stage of machine terminal voltage increase may cause a large number of doubly-fed wind turbines to go off-grid at high voltage

[0004] The existing fault ride-through methods of doubly-fed wind turbines all aim at outputting reactive current and supporting the grid voltage, and cannot distinguish the fault of the sending end grid from the voltage drop caused by LCC-HVDC commutation failure, without considering the impact of output reactive current on LCC -The adverse effect of the terminal voltage rise stage when HVDC commutation fails, so the existing low voltage ride-through control method cannot be applied to the situation of LCC-HVDC commutation failure

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