Development of a predictive out of step relay using model based design

Loss of synchronism can result in the blackout of a part or the whole system. Therefore it is essential that out of step condition in a power system is rapidly and reliably predicted and detected. A novel method of detecting out of step conditions is discussed in this paper. An out of step relay is implemented using model based design approach. The predictive out of step detection is based on fuzzy logic, which processes variables derived from the line voltages and currents measured by the relay. The effectiveness of the method is verified by simulated systems and waveforms recorded from real systems. Various system configurations are considered. Test results show that the relay can rapidly detect various out of step conditions while remain stable during normal conditions and faults.