Active filtering three-phase and four-wire system type photovoltaic grid-connected system and method

Abstract

The invention discloses an active filtering three-phase and four-wire system type photovoltaic grid-connected system and a method. The active filtering three-phase and four-wire system type photovoltaic grid-connected system comprises a DC / DC boost circuit and a DC / AC inverter circuit, wherein the DC / DC boost circuit and the DC / AC inverter circuit are connected in series to form a circuit of a topological structure of the active filtering three-phase and four-wire system type photovoltaic grid-connected system and the decoupling control strategy is conducted on the zero-sequence current of the circuit. The DC / DC boost circuit is used for tracking a maximum power point for photovoltaic power generation. The control of the DC / AC inverter circuit is realized by an electric current loop and an electric voltage loop, wherein the decoupling control strategy is conducted on the zero-sequence current of the electric current loop and the proportion integral (PI) control strategy is conducted on the electric voltage loop. By means of the PI-controlled electric voltage loop, the voltage of a DC bus of an inverter system can be stably controlled and a photovoltaic active current reference value is generated. The method comprises three steps, namely the generation of a reference current, the decoupling control of the zero-sequence current of the electric current loop based on a Dq coordinate system, and the synthesis of a reference voltage and the pulse width modulation. According to the technical scheme of the invention, by means of the electric current loop with the zero-sequence current thereof subjected to decoupling control, not only the output of the photovoltaic active current is tracked and controlled, but also the harmonic current and the zero-sequence current of a neutral line are tracked and compensated. Therefore, the functions of photovoltaic power generation and unbalanced current compensation are realized at the same time.

Description

technical field [0001] The invention belongs to the technical field of solar photovoltaic power generation, and relates to an active filter three-phase four-wire photovoltaic grid-connected system and method, in particular to an active filter three-phase four-wire photovoltaic grid-connected system with zero-sequence current decoupling control and methods. Background technique [0002] With the increasing pressure on energy and environment, solar photovoltaic power generation, as a renewable energy power generation, has been increasingly supported by the national industrial policy and paid attention to by the society. It is one of the most promising forms of new energy power generation at home and abroad. It has become the main development trend of large-scale utilization of solar photovoltaic. The small-scale photovoltaic power generation system realizes grid-connected power generation by connecting to three-phase four-wire power supply systems such as cities and residenti...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to propose an active filter three-phase four-wire photovoltaic grid-connected system and method for zero-sequence current decoupling control, which solves the problems of harmonics and neutral unbalanced current in the three-phase four-wire distribution network , while avoiding the high cost of hardware when using parallel active power filters alone, improving the equipment utilization of photovoltaic inverters and improving the power quality of the three-phase four-wire distribution network system

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