Multi-objective control method for DFIG under unbalanced power grid based on particle swarm optimization

Abstract

The invention discloses a multi-objective control method for a DFIG under an unbalanced power grid based on particle swarm optimization. Consideration is given to output three-phase stator currents, output active power and output reactive power of the DFIG, so that multi-objective optimization control over control performance of the output three-phase stator currents, the output active power and the output reactive power is achieved at the same time, according to the adopted particle swarm optimization, codes are simplified, calculation time is short, which helps real-time calculation to be achieved, operation control performance of the DFIG can be effectively improved under unbalanced power grid voltage conditions, and electric energy quality and stability and safety of a power system are ensured. Meanwhile, a vector proportional integral adjustment or proportional integral resonance adjustment technology is adopted, and angular frequency can restrain adverse effects caused by negative sequence components in power grid voltage for vector proportional integral adjustment or resonance adjustment of double fundamental frequency.

Description

technical field [0001] The invention belongs to the technical field of motor control, and in particular relates to a multi-objective control method of DFIG under an unbalanced power grid based on a particle swarm algorithm. Background technique [0002] Today, DFIG (Double-Fed Wind Generator) has become a mainstream wind turbine type due to its variable-speed constant-frequency four-quadrant operation capability and the small required converter capacity compared to the motor capacity. However, since the stator windings of the DFIG motor are directly connected to the power grid, when a three-phase asymmetrical fault occurs in the power grid, the DFIG unit will have a corresponding deterioration in operating performance: for example, the output of the DFIG stator is unbalanced in the three-phase current, and the output of active and reactive power 100Hz vibration, etc. The deterioration of the above-mentioned performance indicators will cause adverse effects such as the asymm...

AI Technical Summary

Problems solved by technology

However, according to the mathematical model of DFIG, the three control objectives in the traditional control strategy are conflicting with each other, and it is impossible to improve the three-phase stator current, output active power and reactive power of DFIG at the same time.

That is to say, while achieving a certain control target, it will lead to deterioration of the performance of the other two control targets. For example, when the three-phase stator current is kept in balance, the output active power and reactive power will fluctuate violently at 100 Hz, which is not conducive to Reliable and stable operation of the power grid; similarly, when the 100Hz fluctuation of the output active power or reactive power is eliminated, it will cause the imbalance of the DFIG stator current injected into the power grid, which is also not conducive to the reliable and stable operation of the power grid

Therefore, the traditional control strategy of DFIG in an unbalanced power grid can only focus on one of the three control objectives, but cannot take into account all three, so that while achieving a certain control objective, the performance of other objectives will be greatly deteriorated, which is ultimately not conducive to the development of the grid. Stable and reliable operation

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