Method and apparatus for islanding detection for grid tie converters

Abstract

Methods and apparatus are presented for unintentional islanding detection for grid tie converters in which the phase angle disturbance is introduced by modification of grid side converter switching control signals and a mismatch of reactive power between generation and the grid load is formed upon the occurrence of unintentional islanding, where the applied phase disturbance is determined according to two pre-defined curves to form an equivalent positive feedback at different frequencies to prevent the converter from forming an island at a new stable frequency after the grid is disconnected.

Description

Background technique [0001] Power conversion systems are used to convert electrical energy from one form to another. Grid-tie converters may be used in a variety of situations where power is converted from one form to provide power to a load and / or grid. For example, grid-connected converters are used to interface fuel cells, solar cells, wind power systems, batteries and other energy storage systems to the power grid. These converters are generally capable of regenerative operation, where grid power can be converted to DC power for charging a battery, or DC battery power can be converted to provide AC power to the grid. An islanding effect is a situation in which a portion of a regional power system or electricity supply (EPS) is energized by only one or more local EPSs through associated points of common connection or common coupling (PCC), while the regional EPS This part is electrically isolated from the rest of the area EPS. Islanding effects may be planned or unplanne...

AI Technical Summary

Problems solved by technology

However, conventional techniques are far from ensuring accurate identification of unintended islanding in grid converter applications, and thus there remains a need for improved devices and methods for detecting islanding in grid converters

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