Inverting control system and method based on grid drop testing in photovoltaic power generation system

Abstract

The invention discloses an inverting control system and method based on grid drop testing in a photovoltaic power generation system. The method comprises the steps that a photovoltaic array converts solar energy into electric energy, a DC-DC converter carries out MPPT of the photovoltaic power generation system, and an inverter inverts direct current into high-quality alternating current to be sent to a grid; whether the grid drops or not is detected, and if the grid does not drop, an MPPT controller in a pre-controller works, and more energy is obtained from the photovoltaic array; if the grid drops, the MPPT controller in the pre-controller stops working, a first PI controller works, voltage of direct current bus keeps stable in the low-voltage ride through process, a grid-connected current feed unit provides reactive current, and the grid-connected current amplitude is kept constant. The inverting control system and method based on grid drop testing in the photovoltaic power generation system can reduce severe sudden changes of the voltage of the direct current bus in the low-voltage ride through process and prevent the grid-connected current from exceeding a flow value.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation systems, in particular to an inverter control system and method based on grid drop detection in photovoltaic power generation systems. Background technique [0002] In the past few years, photovoltaic grid-connected power generation systems have made great progress in both the number and scale of installations, and the proportion of photovoltaic power generation in the power grid has increased year by year. Driven by the vigorous development of photovoltaic grid-connected systems, many countries have revised new grid codes. In the "Technical Regulations for Connecting Photovoltaic Power Stations to the Grid" issued and implemented by the State Grid Corporation of China on May 6, 2011, it was the first time to clearly put forward the requirements for low voltage ride through (LVRT) for large and medium-sized photovoltaic power stations. It can be seen that photovoltaic system...

AI Technical Summary

Problems solved by technology

Once the power grid falls, the input power of the grid-connected inverter is much greater than the output power, and the extra power generated by the photovoltaic array will be accumulated on the DC bus capacitor, causing the bus voltage to rise

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