A multi-objective optimization direct power control method for vsc under unbalanced power grid based on particle swarm optimization

Abstract

The invention discloses a VSC multi-objective optimization direct power control method in an unbalanced power grid based on a particle swarm algorithm, which takes into account the VSC output three-phase grid current, output active power and output reactive power, so that the control performance of the three can be achieved At the same time, multi-objective optimal control is obtained, and the particle swarm algorithm code adopted is simplified and the calculation time is short, which is conducive to the realization of real-time calculation, and can effectively improve the operation control performance of VSC under the condition of unbalanced grid voltage and ensure power quality. and power system stability and security. In addition, the present invention adopts a direct power control method to ensure a fast transient response of the VSC system. At the same time, the present invention adopts vector proportional integral adjustment or proportional integral resonance adjustment technology, wherein the vector proportional integral adjustment or resonance adjustment whose angular frequency is twice the fundamental frequency can suppress the adverse effects brought by the negative sequence components in the grid voltage.

Description

technical field [0001] The invention belongs to the technical field of power equipment control, and in particular relates to a VSC multi-objective optimization direct power control method in an unbalanced power grid based on a 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...

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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