A photovoltaic power station-level anti-islanding protection method and system

Abstract

The invention provides a photovoltaic power plant station-level island prevention protection method and system. The method comprises the steps of disconnecting all inverters in the photovoltaic powerplant when the grid-connected point bus frequency of the photovoltaic power plant exceeds an island prevention protection range; when the grid-connected point bus frequency of the photovoltaic power plant does not exceed a preset island prevention protection range, determining island formation possibility in the photovoltaic power plant by comparing variable quantity and threshold values of the grid-connected point bus frequency of adjacent two frequency periods; and when it is determined that island formation possibility exists, comparing grid-connected point bus frequency and power frequency, and determining a corresponding preset control strategy according to the comparison result to adjust reactive power output by all the inverters until the grid-connected point bus frequency exceeds the island prevention protection range. Compared with the prior art, the photovoltaic power plant station-level island prevention protection method and system provided by the invention is applicable toisland prevention protection with multiple inverters without causing a monitoring blind area and with high reliability.

Description

technical field [0001] The invention relates to the technical field of active anti-islanding, in particular to a photovoltaic power station-level anti-islanding protection method and system. Background technique [0002] The island phenomenon refers to the state in which a part of the power grid including loads and power sources continues to operate in isolation after being separated from the main grid. Islands can be divided into unplanned islands and planned islands. Among them, planned island operation can effectively play the positive role of distributed power, reduce losses caused by power outages, and improve power supply quality and reliability. Unplanned islands are mainly islands formed by accidental factors such as fault trips. Unplanned island operations may cause serious harm to users and equipment. Power cut. [0003] At present, the anti-islanding protection method of photovoltaic power plants is mainly the local islanding detection method: the grid-connecte...

AI Technical Summary

Problems solved by technology

However, active islanding detection methods can adversely affect grid power quality and transient response

[0008] At the same time, the above-mentioned passive anti-islanding method and active anti-islanding method are only suitable for islanding detection when a single inverter is connected to the grid. When applied to a photovoltaic farm with multiple inverters, the detection effect is significantly reduced, and it may not be normal. Detect islands or malfunction under normal conditions

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