Title :
Negative-Sequence Current Injection for Fast Islanding Detection of a Distributed Resource Unit
Author :
Karimi, Houshang ; Yazdani, Amirnaser ; Iravani, Reza
Author_Institution :
Univ. of Toronto, Toronto
Abstract :
This paper presents an active islanding detection method for a distributed resource (DR) unit which is coupled to a utility grid through a three-phase voltage-sourced converter (VSC). The method is based on injecting a negative-sequence current through the VSC controller and detecting and quantifying the corresponding negative-sequence voltage at the point of common coupling of the VSC by means of a unified three-phase signal processor (UTSP). UTSP is an enhanced phase-locked loop system which provides high degree of immunity to noise, and thus enable islanding detection based on injecting a small (3%) negative-sequence current. The negative-sequence current is injected by a negative-sequence controller which is adopted as the complementary of the conventional VSC current controller. Based on simulation studies in the PSCAD/EMTDC environment, performance of the islanding detection method under UL1741 anti-islanding test is evaluated, and its sensitivity to noise, grid short-circuit ratio, grid voltage imbalance, and deviations in the UL1741 test parameters are presented. The studies show that based on negative-sequence current injection of about 2% to 3%, islanding can be detected within 60 ms even for the worst case scenario.
Keywords :
distribution networks; power convertors; power grids; EMTDC; PSCAD; active islanding detection method; distributed resource unit; fast islanding detection; grid short-circuit ratio; grid voltage imbalance; negative-sequence current; negative-sequence current injection; phase-locked loop system; three-phase voltage-sourced converter; unified three-phase signal processor; utility grid; Converters; PSCAD; Phase detection; Phase locked loops; Phase noise; Power conversion; Signal processing; Testing; Voltage control; Working environment noise; Distributed resource (DR); UL1741 test; islanding detection;
Journal_Title :
Power Electronics, IEEE Transactions on
DOI :
10.1109/TPEL.2007.911774