Particle swarm algorithm based VSC multi-target optimization direct power control method under imbalanced electrical network

Abstract

The invention discloses a particle swarm algorithm based VSC multi-target optimization direct power control method under an imbalanced electrical network, which takes into consideration the output three-phase electrical network current, the output active power and the output reactive power of a VSC, enables the control performance of the three to simultaneously obtain multi-target optimization control, employs concise particle swarm algorithm codes, consumes quite short calculating time, facilitates realization in a real-time calculation aspect, can effectively improve the operation control performance of the VSC under imbalanced electrical network voltage conditions, and ensures the quality of electric energy and the stability and safety of en electrical power system. Moreover, a direct power control method is adopted in the invention so that the transient rapid response of a VSC system is ensured. At the same time, a vector proportion-integration adjustment technology or a proportion-integration resonance adjustment technology is adopted in the invention, and vector proportion-integration adjustment or resonance adjustment whose angular frequency doubles a fundamental frequency can inhibit unfavorable influences brought by negative phase-sequence components in electrical network 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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