Doubly-fed wind power generator quick weak magnetic control method

Abstract

The invention discloses a doubly-fed wind power generator quick weak magnetic control method. In a steady state, all variables are based on a two-phase synchronous rotating coordinate system. The change in active power and the change in reactive power of a stator in a sampling period are predicted; then, the power in the next sampling period is compensated; and finally, the rotor voltage is calculated, and PWM modulation is conducted. By adopting the method, the fluctuation of active power and reactive power of the stator is reduced. When the grid voltage drops, all the variables are based on a two-phase static coordinate system. Quick weak magnetic control on rotor flux is realized through a rotor voltage prediction model, coordinate transformation is performed on the predicted rotor voltage under the two-phase static coordinate system to obtain the rotor voltage under a two-phase rotor speed rotating coordinate system, and finally, PWM modulation is conducted. Through quick weak magnetic control, the rotor current can be controlled within 1.5-1.6 times of the rated current, and the electromagnetic torque ripple is small in the fault period. The operation capacity of a doubly-fed wind power generator in fault is improved.

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...

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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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