Control circuit for stand-alone /grid-connected dual-mode inverter and switching technology thereof

Abstract

The invention discloses a control circuit for a stand-alone / grid-connected dual-mode inverter and a switching technology thereof. During grid-connected operation, a current loop PI (Proportional-Integral) control mode with power grid voltage feed-forward is adopted to enable grid connected current to have the same amplitude, frequency and phase with the voltage of a power grid. During stand-alone operation, a voltage loop PI control mode with feed-forward is adopted to control the amplitude and the frequency of a voltage output by a target to the inverter to meet load requirements. A dual-mode control strategy is realized by a method combining software and hardware. A micro-controller provides a carrier wave clock signal, a reference sine wave data table and a software phase locking control and mode selecting signal, and the control circuit comprises a triangular carrier wave generation circuit, a reference sine wave generation circuit, a current and voltage feedback link, a dead zone setting circuit and a single frequency doubling SPWM (Sinusoidal Pulse Width Modulation) circuit. The method provided by the invention has the advantages that the design difficulty of the inverter is lowered, the software of the microprocessor is simple to program, the delay of the control link is short, the seamless smooth switching between the stand-alone and grid-connected dual modes can be realized, and the work is stable and reliable.

Description

technical field [0001] The invention relates to a control circuit and a switching method of an independent / grid-connected dual-mode inverter, belonging to the technical field of new energy power generation. Background technique [0002] Distributed power generation units such as photovoltaic power generation and wind power generation have the advantages of being clean and pollution-free, and are one of the important ways to solve energy and environmental problems in the future. With the continuous development of new energy generation technology, a microgrid that can integrate various distributed energy sources is an effective way to save investment, improve grid stability and improve power quality. The power supply in the distributed generation system usually has two working modes: independent power generation and grid-connected power generation. In the case of sufficient energy, the system works in the grid-connected mode. In addition to ensuring the normal operation of lo...

AI Technical Summary

Problems solved by technology

[0004] There is no mature independent / grid-connected dual-mode inverter in the market today, which can meet the performance requirements of independent power generation and grid-connected power generation and perform fast and effective mode switching, and complex theoretical control strategies are not suitable for developing stable and reliable inverters. product

Images