A high and low voltage ride through cooperative control method for doubly-fed wind turbines

Abstract

The invention discloses a cooperative control method of high and low voltage ride-through for a doubly-fed wind turbine set. According to the method, according to monitored stator end voltage level of the doubly-fed wind turbine set, the operating state of the doubly-fed wind turbine set is divided into three operating modes, to be specific, a normal node, a low voltage ride-through mode and a high voltage ride-through mode; by modifying a rotor side converter control structure, attenuation of direct current and negative sequence component in stator flux linkage of the doubly-fed wind turbine set after a failure occurs is accelerated, and quick injection of reactive current is made possible; according to rotor three-phase current and direct-current bus voltage level monitored in real time, breakover trigger logic of a hardware protective module is optimized, and operational safety of a set transformer and an alternating-current bus capacitor is protected. Especially, the provided cooperative control of high and low voltage ride-through and a protective scheme are implemented completely on basis of existing low voltage ride-through hardware of the set, no additional hardware protective equipment is required, and a general voltage fault ride-through implementing scheme for handling abrupt changes in grid voltage amplitude is provided.

Description

technical field [0001] The invention relates to a wind power generation technology, in particular to a non-off-grid operation technology of a doubly-fed wind generator set under a grid voltage amplitude sudden change fault. The proposed high-low voltage ride-through cooperative control method for doubly-fed wind turbines can flexibly switch control modes when generalized voltage dips and sudden rises occur at the grid-connected points of wind turbines, and meet grid-connected regulations. requirements. Background technique [0002] With the substantial increase in the proportion of wind power in the power grid, major wind power countries in the world have successively issued grid-connected regulations, which put forward clear requirements for the operational reliability of grid-connected wind turbines. Among them, the more typical ones are the non-off-grid operation requirements of wind turbines under grid voltage drops and sudden rises, which are commonly referred to as lo...

AI Technical Summary

Problems solved by technology

According to the existing literature research, there are still two deficiencies in the understanding of this problem: 1) The impact of grid voltage surge faults on the complete DFIG unit system including grid-side and rotor-side converters has not been studied in depth , the key factors restricting the DFIG high voltage ride-through capability have not been clarified; 2) Existing control strategies often only partially improve the fault ride-through performance of DFIG wind turbines, without considering the "contribution" of the wind turbine to the faulty grid, especially ignoring grid connection The guidelines set the reactive current requirements for DFIG units, so it is difficult to achieve real high voltage ride-through

In this regard, no literature has proposed generalized voltage fault ride-through operation technology for wind turbines including LVRT and HVRT

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