Fast field-weakening control method for doubly-fed wind turbine

Abstract

The invention discloses a fast magnetic field weakening control method for a double-fed wind power generator. In the steady state, all variables are based on the two-phase synchronous rotating coordinate system. By predicting the variation of stator active power and reactive power in a sampling period, and then compensating the power in the next sampling period, the rotor voltage is finally calculated, and then After PWM modulation, this method reduces the fluctuation of active power and reactive power on the stator side. When the grid voltage drops, all variables are based on the two-phase static coordinate system. Through the prediction model of the rotor voltage, the rapid flux-weakening control of the rotor flux linkage is realized, and the predicted rotor voltage in the two-phase static coordinate system is converted into two-phase The rotor speed is the rotor voltage in the rotating coordinate system, which is finally modulated by PWM. Fast field weakening control can effectively control the rotor current within 1.5-1.6 times the rated current, and the electromagnetic torque ripple is small during the fault period, which improves the fault operation capability of the doubly-fed wind turbine.

Description

technical field [0001] The invention belongs to the field of doubly-fed wind-driven generator operation control, and relates to a steady-state power prediction control and a rapid field-weakening control method when the power grid drops sharply, improving the stability during normal operation and the faulty operation capability of the doubly-fed wind-driven generator in a fault state . Background technique [0002] In recent years, with the continuous increase of the stand-alone capacity of wind turbines, the proportion of wind power in the power grid is increasing. Although the utilization of wind power generation has brought huge economic benefits, it has also caused certain damage to the stability of the power system. The large-scale off-grid of wind turbines caused by power grid slump or swell faults will have a great impact on the normal operation of the grid. In order to ensure the stability of the power system, it is necessary to improve the fault operation capabilit...

AI Technical Summary

Problems solved by technology

[0004] In the case of grid voltage slump, the current control to achieve fault operation capability is to achieve fault operation capability by improving the excitation control strategy. This method is suitable for mild faults. In the case of deep grid voltage drops, this excitation control Algorithms are difficult to realize fault operation control of power generation system

In addition, the rotor is added with crowbar protection to achieve fault operation. This method requires a hardware structure, which is costly and complicated.

When the power grid voltage has a single-phase drop of 90% or a three-phase symmetrical drop of 70%, most of the current control methods are difficult to control the rotor current value during the fault period within 2 times of its rated current, and the electromagnetic torque fluctuation is relatively large. The impact force of the unit is great

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