Multi-inverter microgrid quick island detection method

Abstract

The invention relates to a multi-inverter microgrid quick island detection method. The method, on the basis of real-time measurement of voltage effective value VPCC at the PCC place, and frequency and load reactive power, is characterized by comparing the voltage measurement value and a voltage rated value under normal condition, as well as the frequency and rated value 50Hz, and adopting a corresponding IBDG reactive power control strategy; when carrying out island judgment, presetting a voltage threshold value and a frequency threshold value in advance, and comparing the VPCC with the voltage threshold value; if the VPCC surpasses the voltage threshold value, directly judging the microgrid is in an island state, and terminating the current island detection; or otherwise, comparing the measured frequency f with the frequency threshold value, and if the measured frequency f surpasses the frequency threshold value, judging the microgrid is in the island state. The method does not have island detection dead zone, has universality, and is not only suitable for unity power factor operation IBDG but also suitable for non-unity power factor operation IBDG.

Description

technical field [0001] The invention belongs to the field of micro-grid protection and control in power systems, and aims at the problem of unplanned islanding of micro-grids that may occur, and proposes a fast island detection method suitable for multi-inverter micro-grids. Background technique [0002] The occurrence of unplanned island operation of microgrid is accidental and uncertain. When the public coupling point or its upstream circuit breaker trips due to misoperation, system failure, etc., the distributed power generation in the microgrid may not be able to detect that the microgrid has been disconnected from the system in time and continue to operate. At this time, the unplanned island operation of the microgrid may bring a series of problems to the safe and stable operation of the power system, such as reclosing failure, extended or even failure of backup and automatic switching time, and deterioration of power quality in the island system. Personal safety of op...

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Problems solved by technology

However, when the grid-connection points of multiple IBDGs are at different locations, especially when the distance between different grid-connection points is long and the power transmitted on the line between two grid-connection points is large, if unplanned islanding occurs, then The voltage values ​​of grid-connected points of IBDG at different locations may be above and below the rated voltage, and their reactive power disturbances will cancel each other out, which cannot guarantee the effectiveness of islanding detection

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