Ultra fast relay with small communication requirements

Protection relays play a very important role in network security. Both the network stability and energy availability depend to a great extent on algorithms and protection concepts. This paper presents a novel, very fast protection algorithm that is based on directional comparison. The algorithm is robust against many states and phenomena appearing in the network, e.g. load flow fluctuation, power swings or frequency deviations. The method is also robust against some phenomena connected with secondary system design like CTs saturation, synchronisation deviation or the transient effects in CVTs. The small communication requirements mean that this concept can be applied in existing power networks protected by differential relays with limited band width. The main idea of the algorithm as well as an example is presented in this paper.