A blocking scheme for enhancement of distance relay security under stressed system conditions

摘要: Abstract Mal-operation of zone-3 distance relays has been one the main causes widespread disturbances and blackouts in power systems throughout world. Under some non-faulty conditions, measured impedance may enter cause spurious trip transmission lines. This can happen during stressed system conditions such as swing, extreme loading voltage decline. In this respect, there is an essential need to improve security zone-3. Introducing a new two-dimensional decision plane, paper presents technique based on superimposed components voltages magnitude discriminate from fault events. way, not only rate change but also its pattern included into logic. The proposed method able provide high sensitivity detecting cases prevents relay undesired conditions. 39-bus New-England test used demonstrate effectiveness method. obtained results show that reliably distinguish events for different considerably improves relay.