Comprehensive investigation of the voltage relay for anti-islanding protection of synchronous distributed generation

摘要

Interconnection standards prevent islanding operation of distributed generationsrn(DGs) to keep the safety and avoid the equipment failure. To meet this requirementrnfor synchronous DGs (SDGs), the frequency-based relays are commonly used in thernactive distribution networks. This paper shows that in some conditions, a voltagernrelay has better islanding detection performance than a frequency relay regardingrnthe SDG operating point, power factor of loads, and network characteristics. In thisrnpaper, a method is proposed for adjusting and evaluating a voltage relay based onrnapplication region and power imbalance application region to satisfy the islandingrndetection and safe and abnormal voltage variation criteria and to eliminate thernfalse operation for the non-islanding disturbances including load shedding, loadrnrestoration, and 3-phase short-circuit fault, as far as possible. The relay false operationrnis studied for a combination of the control mode of SDG excitation systemrnand the load type that leads to the highest possibility of relay false operation forrnthe non-islanding disturbances. A number of dynamic simulation case studies arernconducted to investigate the characteristics and capabilities of the proposed SDGrnanti-islanding protection scheme in both single- and multi-DG systems.