A new computer-based relaying technique for power system protection

This paper introduces a novel computer-based protection technique of power systems that does not require any coordination process. The proposed technique comprises two main phases: an offline phase and an online phase. The offline phase is based on an algorithm based an a graph-theoretical approach to determine the break point sets (BPSs) for a predefined fault location. The determined BPSs are then grouped according to the number of healthy components forced to out and/or loss of load. The offline phase consists of scanning all conceivable fault locations within the power system. Then the algorithm is repeatedly applied for each of them and the BPSs are computed and stored in a file whose name is related to the fault. The online phase is a real time application of computer-based relaying. On the detection of a fault, the algorithm retrieves the appropriate file related to that fault and transmits the tripping signals to the circuit breakers of the first group of the BPSs. A two-way communication acknowledges the actual states of the circuit breakers and reflects back the topology of the network to the computer. If the fault is successfully cleared the algorithm stops, otherwise the procedure is repeated. This technique is applicable to all faults that be detected and reflected to the computer. The proposed protection scheme is simple and reliable for any communicative power system. The paper includes an illustrative example that highlights the salient features of the proposed algorithm