Parallel control system and parallel control method for inverters

Abstract

The invention belongs to the technical field of parallel control for inverters, and particularly relates to a parallel control system and a parallel control method for inverters. The parallel control system and the parallel control method are based on a combination of feed-forward of average transient current and power regulation. Control for feed-forward of the average transient current and the power regulation are combined, equivalent output impedance among the inverters is increased by feed-forward of the average transient current, harmonic circulating current is suppressed, equivalent output impedance at a load end of a parallel system is reduced, the load adaptability is improved, and the harmonic current-sharing response speed is guaranteed. An active voltage regulation and reactive frequency modulation mode is adopted for power regulation, so that fundamental current sharing of the parallel system is realized, fundamental circulating current is effectively suppressed, and reliable running of the parallel system is guaranteed. The parallel control system and the parallel control method have the advantages that the system is simple in structure and is high in reliability owing to a redundancy design, a design for a super-power inverter can be implemented, and steady-state and transient performance indexes of the system are excellent.

Description

technical field [0001] The invention belongs to the technical field of inverter parallel control, and specifically relates to an inverter parallel control system and control method based on the combination of instantaneous average current feedforward and power regulation. Background technique [0002] With the development of society, the application of power system (essentially inverter) is more and more extensive, and people's requirements for it are getting higher and higher, and the shortcomings of a single unit are becoming more and more obvious, so the research and application of inverter parallel system appear increasingly important. [0003] The currently used inverter parallel control technologies mainly include the following types: centralized control, master-slave control, decentralized logic control, and no interconnection control. The active and reactive power adjustment method can achieve better current sharing effect and steady-state index, but due to the exis...

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Problems solved by technology

[0003] The currently used inverter parallel control technologies mainly include the following types: centralized control, master-slave control, decentralized logic control, and no interconnection control. The active and reactive power adjustment method can achieve better current sharing effect and steady-state indicators, but due to the existence of interconnection lines, the reliability is low, the system is complex, and the redundancy is poor

The non-interconnection wire control method has high reliability and a simple system because the interconnection wire is cancelled. However, because this method adopts the power regulation method, the regulation lags behind by one cycle and the dynamic performance is poor; in addition, this method is based on the fundamental wave. , when there is a nonlinear load, especially a rectifying load, the harmonic current sharing effect is not ideal, and it is greatly affected by the parallel impedance, and it even has a relationship with whether it can be successfully paralleled.

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