Method for controlling output power of photovoltaic inverter

Abstract

The invention provides a method for controlling output power of a photovoltaic inverter. The method comprises the following steps: detecting the rate of change of the direct current bus voltage of the photovoltaic inverter; and when the direct current bus voltage is reduced and the rate of change is more than the threshold, reducing the output power of the photovoltaic inverter so that the photovoltaic inverter keeps grid-connected. The method is characterized by judging whether the photovoltaic cell pack is shadowed according to the rate of change of the direct current bus voltage based on the power change prediction, reducing the output power at the right time to ensure the photovoltaic cell pack and the photovoltaic inverter to be newly balanced and maintaining the direct current bus voltage to ensure the inverter to be continuously grid-connected. The method has the following advantages: the calculation amount is small; the reliability is high; the photovoltaic inverter can be effectively avoided from breaking away from the grid when being suddenly shadowed; and the method is easily applied in practice.

Description

technical field [0001] The invention relates to the field of photovoltaic power generation, in particular to a method for controlling output power of a photovoltaic inverter. The method is based on the output power variation prediction of the photovoltaic inverter. Background technique [0002] At present, photovoltaic grid-connected inverters are widely used in the field of photovoltaic power generation. In practical applications, photovoltaic cell components may encounter shadows caused by clouds or buildings, for example, resulting in a reduction in the output power of the photovoltaic cell components. At this time, if the photovoltaic inverter maintains the power generation before the shading occurs, the bus voltage of the inverter will drop rapidly. When the bus voltage is lower than the minimum grid-connected voltage, the photovoltaic inverter will be disconnected from the grid. This situation is most common at noon when the amount of sunlight changes drastically. I...

AI Technical Summary

Problems solved by technology

In practical applications, photovoltaic cell components will encounter shadows caused by clouds or buildings, for example, resulting in a reduction in the output power of photovoltaic cell components

At this time, if the photovoltaic inverter maintains the power generation before the shading occurs, the bus voltage of the inverter will drop rapidly, and when the bus voltage is lower than the minimum grid-connected voltage, the photovoltaic inverter will be disconnected from the grid

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