A coordinated control method for high-voltage ride-through of double-fed asynchronous wind turbines

Abstract

The invention discloses a coordination control method for double-fed asynchronous wind driven generator high voltage ride through, on the basis of a mathematical model of a double-fed asynchronous wind driven generator and gird side and rotor side converters of the double-fed asynchronous wind driven generator, allocation principles of active and reactive power of the grid side and rotor side converters of the double-fed wind driven generator are calculated, extremity expressions of active and reactive current are given, and a high voltage ride through implementation scheme capable of effectively providing dynamic reactive support for a power grid and eliminating direct current bus voltage, active power, reactive power and electromagnetic torque ripples is provided. The coordination control method in the invention can overcome defects of weak ride through capability and poor power grid stability of a wind driven generator in the prior art, thereby achieving the goal of optimal control of the generator when the power grid voltage is high; and the method can perfectly be implemented on the basis of original low voltage rid through hardware, thereby realizing joining with an existing low voltage ride through scheme of the unit, and forming a generalized voltage fault ride through control strategy capable of coping with a sudden change of amplitude of network voltage.

Description

Technical field [0001] The invention belongs to the technical field of wind generator control, and specifically relates to a coordinated control method for high voltage ride through of a double-fed asynchronous wind generator. Background technique [0002] In the double-fed asynchronous wind power generator (DFIG) system, the stator of the generator is directly connected to the grid through a transformer, and the failure of the grid will directly affect the operation of the generator itself. In addition, the capacity of the excitation converter connected to the rotor is limited, and it can only control the generator with limited capacity. Compared with the wind power system based on the full power converter, the double-fed asynchronous wind power system is very sensitive to grid faults. The ability to bear is also poor. [0003] At present, a large number of inventions and studies are related to the impact of grid voltage sag on wind turbines and low voltage ride-through (LVRT) te...

AI Technical Summary

Problems solved by technology

Obviously, in these hardware-based solutions, due to the addition of a complete set of hardware systems, the cost is greatly increased, and the design and control of the system are also more complicated.

[0005] However, many HVRT inventions based on improved system control strategies did not discuss in depth the operation safety requirements of the grid-side converter and rotor-side converter of the wind turbine during the grid voltage surge, nor did they analyze the two converters and their mutual relationship. The proposed control strategy has not considered the dynamic reactive power support capability of wind turbines, and it is difficult to meet the increasingly stringent grid connection requirements of wind turbines in grid-connected guidelines, and some of them are only given from the perspective of converters. The solution of HVRT is not fully considered, and the electromagnetic transient characteristics of the motor itself are not fully considered.

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