Model Predictive Control Method for Doubly-fed Wind Turbine Without Off-grid

Abstract

The invention discloses a model predictive control method for a doubly-fed wind power generator that does not go off-grid. When the grid voltage drops, the rotor flux linkage predictive control method is adopted, and the optimal voltage vector is selected by predicting the rotor flux linkage to act on the rotor side transformation. The controller realizes the synchronous control of the rotor flux and the stator flux, and weakens the fault impact of the stator flux on the rotor flux, thereby reducing the rotor fault overcurrent. Compared with the model predictive control in the steady state, the control frequency of the rotor flux prediction method used in the grid fault is doubled, the response to the fault is faster, and the rotor current can be effectively controlled by 1.5-1.6 times in the fault state Within the rated current, the electromagnetic torque fluctuation is small, which improves the ability of the doubly-fed wind turbine not to go off-grid during a fault.

Description

technical field [0001] The invention specifically relates to a model predictive control of a rotor-side converter of a doubly-fed wind power generator during normal operation of a power grid and a method for predictive control of rotor flux linkage when the power grid voltage drops, and belongs to the technical field of doubly-fed wind power generator operation control. Background technique [0002] Wind power generation is the process of converting wind energy into mechanical energy and then into electrical energy. The role of the wind turbine and its control system is to convert wind energy into mechanical energy, while the generator and its control system convert mechanical energy into electrical energy. Doubly-fed wind turbine is the mainstream model of wind power generation, so the research on its control performance is very important. There are two main operating objectives of doubly-fed wind turbine. The first is to achieve the maximum wind energy tracking under the pr...

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Problems solved by technology

When the grid voltage drops, the double-fed wind turbine adopts the rotor flux linkage predictive control method, and selects the optimal voltage vector to act on the rotor side converter by predicting the rotor flux linkage, so as to realize the synchronous control of the rotor flux linkage and the stator flux linkage. Weaken the fault impact of the stator flux linkage on the rotor flux linkage, thereby reducing the overcurrent of the rotor fault. When the power grid voltage falls by 90% in a single phase or 70% in three phases, most of the current control methods have little effect on the rotor current value during the fault period. It is difficult to control it within 2 times of its rated current, and the electromagnetic torque fluctuates relatively large, which has a great impact on the unit

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