Asymmetric direct power control method for dual feed asynchronous wind power generator

Abstract

The invention discloses a method for controlling asymmetric direct power of doubly-fed asynchronous wind power generators. The method comprises the following steps that: by collecting voltage and current signals of a three-phase stator of a DFIG, instantaneous active power and reactive power output by the DFIG stator are calculated; error signals between the instantaneous active / reactive power of the stator and given active / reactive power are regulated by utilizing a proportional regulator and two resonant regulators; output signals of the three regulators are added and then decoupled through feedback compensation so as to obtain a reference voltage signal of a rotor in a rotor-speed rotational coordinate system; a switching signal of the operation of a rotor-side converter is generated through space vector pulse-width modulation so as to control the operation state of the DFIG; and the method can eliminate fundamental-frequency fluctuation and double-frequency fluctuation in the output power of the stator, which are caused by voltage asymmetry of power networks, and does not need to decompose positive / negative-sequence components, thereby avoiding introducing decomposition time delay and errors. Therefore, the method can enhance the capability of controlling wind power generating sets under the circumstance that the power networks have asymmetric faults, and improve the uninterrupted operation capability of the wind power generation systems with the faults.

Description

technical field [0001] The invention relates to the wind power generator control technology in the field of energy, in particular to an asymmetric direct power control method of a doubly-fed asynchronous wind power generator. Background technique [0002] Modern large-scale wind power generation systems mainly include double-fed asynchronous generators (DFIG) and permanent magnet synchronous generators. In order to improve power generation efficiency, variable-speed constant-frequency power generation operations are implemented, and the DFIG system is the current mainstream model. At present, my country's wind power technology mostly stays in the operation control under ideal grid conditions. Since the actual grid often has various symmetrical and asymmetrical faults, it is necessary to carry out research on operation control under grid faults and propose corresponding control technologies. In recent years, international research on DFIG unit control technology has mostly fo...

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Problems solved by technology

figure 1 In the traditional control method shown, the separation of positive and negative sequences generally adopts 2ω s Frequency notch filter 16 (or low-pass filter, 1 / 4 grid voltage fundamental wave period delay and other methods), in addition to introducing delay in the separation, the control system bandwidth will be affected, which will cause dynamic tracking error and dynamic control effect not ideal

What's more, the circuit cannot distinguish whether the grid voltage is balanced or asymmetrical. If the DFIG operates in a state of strict grid voltage balance, the control system will still use the notch filter to separate the rotor variables, which will bring problems to the normal control of the system. Unnecessary delay seriously affects the dynamic control performance of the system

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