Method for detecting island of grid-connected photovoltaic power system on basis of electric energy quality constraint

Abstract

The invention discloses a method for detecting an island of a grid-connected photovoltaic power system on the basis of the electric energy quality constraint. A detection unit is used for comparing an operating voltage of a grid-connected point of the grid-connected photovoltaic power system with a rated voltage of the grid-connected point to further periodically change a trigger pulse duty ratio of a Boost circuit in the grid-connected photovoltaic power system so that an output voltage of a grid-connected photovoltaic inverter is regulated according to a designated proportion, then comparing a voltage variable quantity of the grid-connected point of the grid-connected photovoltaic power system, which is measured at the moment, with a set island detection voltage variable quantity threshold value and finally determining whether the island occurs. According to the invention, not only can an undetectable region existing in a passive detection method when an output power of the grid-connected photovoltaic inverter is matched with a load power be avoided, but also the problem of electric energy quality, which is caused by the existing active detection method, can be solved. The method disclosed by the invention has strong adaptability to the operation of a power grid and is convenient for actual engineering application.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic grid-connected power generation, and in particular relates to an island detection method for a photovoltaic grid-connected power generation system taking into account power quality constraints. Background technique [0002] Today, with energy depletion and environmental pollution becoming more and more serious, solar energy utilization has become a hotspot for the development of countries all over the world. Photovoltaic grid-connected power generation, as the main development trend of solar energy utilization, has developed rapidly. [0003] In addition to basic protection functions, photovoltaic grid-connected power generation systems should have special functions to prevent islanding effects during grid-connected operation. The so-called island effect refers to: when the power grid trips and stops power supply due to failure or power outage maintenance, the distributed grid-connected power...

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Problems solved by technology

[0006] Aiming at the deficiency mentioned in the above background technology that the existing islanding detection method does not consider the impact on the power quality of the power grid, the present invention proposes a photovoltaic grid-connected power generation system islanding detection method that takes into account power quality constraints

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