Multi-target control method for VSC (voltage source converter) under unbalanced power grid based on particle swarm algorithm

Abstract

The invention discloses a multi-target control method for a VSC (voltage source converter) under an unbalanced power grid based on a particle swarm algorithm. The multi-target control method gives consideration to output three-phase power grid current, output active power and output reactive power of the VSC, control performances of the output three-phase power grid current, the output active power and the output reactive power can be controlled in a multi-target optimized manner, codes of the particle swarm algorithm are simplified, computing time is short, real-time computing can be realized, the running control performance of the VSC under the condition of unbalanced power grid voltage can be effectively improved, and quality of electric energy and stability and safety of an electric power system are ensured. By the aid of vector proportional-integral control or proportional-integral resonance control technology, angular frequency is obtained by performing vector proportional-integral control or resonance control on double fundamental frequency, and negative influence caused by negative sequence components in the power grid voltage can be restrained.

Description

technical field [0001] The invention belongs to the technical field of power electronic equipment control, and in particular relates to a multi-objective control method of VSC under unbalanced power grid based on particle swarm algorithm. Background technique [0002] Nowadays, as a simple and reliable power electronic device, VSC (Voltage Source Converter) is widely used in actual power grids. The most common devices are grid-side converters used in wind power generation systems, and Grid-side converters, active power filters and power factor correction devices to ensure safe and reliable operation of the grid, etc. However, the VSC operating under the condition of unbalanced grid voltage will show unbalanced three-phase output current, output active power, reactive power oscillation and other operational performance deterioration. The deterioration of the above performance indicators will cause adverse effects such as grid current harmonic injection and grid power oscilla...

AI Technical Summary

Problems solved by technology

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

That is to say, when a certain control target is achieved, the performance of the other two control targets will deteriorate. For example, when the three-phase grid current is balanced, 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 lead to an unbalanced 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 VSC under unbalanced power grid can only focus on one of the three control objectives, but cannot take into account the 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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