Doubly-fed wind generator rotor linkage constant-frequency model prediction control method

Abstract

The invention discloses a doubly-fed wind generator rotor linkage constant-frequency model prediction control method. According to the method, a three-voltage-vector selection method is selected based on the determination of the rotor linkage variation, a voltage vector selection mode requires that two effective vectors and a zero vector adjacent to the sector where a rotor voltage vector is are selected during each switching period, the rotor linkage follows a given value and optimizes the given value in real time to make the given value synchronous with the actual value of the stator linkage, and in order to weaken the fault impact of the stator linkage to the rotor linkage, the acting time of the selected effective vectors and the zero vector is determined based on a value function minimizing principle, and the switching state signals are obtained through the adoption of modulation technology. The method controls the converter by taking the rotor linkage error as the minimum during the switching period, and realizes the rapid tracking control of the rotor linkage. The switching frequency is constant, higher sampling frequency is not needed, control precision is high, and the rotor current can be effectively controlled within the allowed maximum current.

Description

technical field [0001] The invention belongs to the technical field of fixed-frequency model predictive control of doubly-fed wind power generators, in particular to a doubly-fed wind power generator rotor flux fixed-frequency model predictive control method under power grid faults, which is used to effectively improve the performance of doubly-fed wind power generators in power grid faults The ability to operate without going offline. Background technique [0002] In recent years, renewable energy technology has developed rapidly, and the utilization of wind energy occupies a large proportion. Wind energy is a kind of clean energy, which has the advantages of inexhaustible and pollution-free, and is a very ideal new energy. The proportion of wind power generation in power supply is gradually increasing. The doubly-fed wind power generator is currently the model with the largest market share and installed capacity. It is greatly affected by grid failures. The protection st...

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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.

There are also some literatures that have studied the direct power control method using the hysteresis controller and the look-up table method. This method eliminates the current control loop in the vector control and simplifies the control structure, but this control method has the converter switching frequency The disadvantage of not being fixed will cause broadband harmonic current to be injected into the grid, resulting in complex filter reactor design

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