Fault operation method under doubly-fed wind power generator direct power control

Abstract

The invention discloses a fault operation method under doubly-fed wind power generator direct power control. By adopting the control method, complicated coordinate transformation and compensation adjustment in vector control are avoided, and the control instruction is simple, direct and easy to implement. When the grid voltage sags, weak-magnetic rotor flux prediction control is adopted, the given value of rotor flux is worked out based on the actual value of stator flux, the dynamic behaviors of a doubly-fed wind power generator rotor-side converter in different switching states are predicted according to a discrete model of voltage of the converter, seven voltage vector prediction results are evaluated through a value function, and finally, a voltage vector minimizing the value function is chosen. By adopting the algorithm, the optimal switching state can be predicted as a switching signal of the converter in each sampling period. The method needs neither synchronous rotating coordinate system conversion nor PI regulator design, and has the advantages of fast dynamic response, simple control instruction, and easy implementation. The operation capacity of a doubly-fed wind power generator in fault is improved.

Description

technical field [0001] The invention belongs to the technical field of control of a doubly-fed wind power generator rotor side converter, and is respectively aimed at a direct power control method when the grid voltage is in a steady state and a rotor flux-linkage flux-weakening predictive control method when the grid voltage suddenly drops. Background technique [0002] Wind energy is a random, explosive, and uncertain energy source. The random fluctuation of electric energy generated by the wind power generation system has a great impact on the power grid. How to maintain the voltage of the power grid when the wind power generation system and power loads are in a fluctuating state The amplitude and frequency are within the allowable range, and how to ensure the stability of the grid operation during the dynamic adjustment process of the wind turbine is the requirement of the wind power generation system for the grid. These problems must be seriously faced and resolved, oth...

AI Technical Summary

Problems solved by technology

This method increases the cost of hardware, and absorbs a large amount of reactive power from the grid when a fault occurs, which affects the stability of the grid, and the transient electromagnetic impact on the grid and the mechanical impact of the wind turbine are very serious.

When the grid voltage has a single-phase 90% or three-phase symmetrical drop of 70% or more serious faults, the rotor current of the doubly-fed wind turbine can hardly be controlled within 2 times the rated current, which will cause serious damage to the unit.

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