A method and system for virtual synchronous control of doubly-fed wind turbines

Abstract

The invention discloses a virtual synchronous control method and system of a doubly-fed wind generating unit. The method comprises the following steps: performing improved virtual synchronous controlon an acquired stator voltage three-phase alternating-current signal and a stator output current three-phase alternating-current signal of a doubly-fed generator to obtain a stator voltage instructionand a stator virtual synchronous angular frequency instruction of the doubly-fed generator; calculating the collected rotor rotation angular speed of the doubly-fed generator and the stator virtual synchronization angular frequency instruction to obtain a positive sequence slip angle and a negative sequence slip angle of the doubly-fed generator; and performing positive sequence control and negative sequence control based on the positive sequence slip angle, the negative sequence slip angle and the stator voltage instruction, and generating an SVPWM control signal of a doubly-fed generator rotor side converter switching tube. According to the method, the condition that three-phase imbalance occurs in stator end current under the unbalanced power grid voltage is considered, and the three-phase balance of the stator current is realized by adding the negative sequence control loop under the existing virtual synchronous control strategy.

Description

technical field [0001] The invention relates to the technical field of wind power generation conversion technology, in particular to a virtual synchronous control method and system for a doubly-fed wind power generating set. Background technique [0002] Wind energy has emerged as one of the most widely used renewable energy sources due to the rapid consumption of fossil fuels and growing concern for the environment. However, the renewable energy power generation system contains a large number of power electronic conversion devices. With the gradual increase of the penetration rate of renewable energy in the power distribution system, the power grid presents the characteristics of low inertia and weak damping, and the probability of grid voltage imbalance also increased substantially. In recent years, the idea of ​​virtual synchronization realized through the simulation of synchronous machine speed and exciter characteristics can meet the corresponding requirements, but the...

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Problems solved by technology

The existing solution one is to add a fault detection module to the virtual synchronous control strategy of steady-state operation, and switch to the fault operation mode when the grid voltage unbalance fault occurs. The disadvantage of this solution is that additional faults are required The detection time and mode switching time have low reliability; the second existing solution is to replace the proportional-integral regulator in the voltage and current double closed-loop with a proportional-resonant regulator or a proportional-integral-resonant regulator. The disadvantage of the scheme is that the ability to suppress the unbalanced current is limited and the effectiveness is low

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