Smart automatic synchronization system based on coherence algorithm for power grids

Abstract

An automatic synchronizing system is useful to reconnect two separated segments of a power system. This article describes a smart synchronizer based on coherence indices computed for voltage and current waves to value the synchronization level during normal operating conditions. The coherence index is a measure of the similarity degree between two time-series waves taken from the two subsystems. Thus, it can be used to detect any system disturbance, and to identify the synchronous operation. To investigate the technique performance, a power system with real parameters' data is simulated on Alternative Transient Program (ATP) platform, and the algorithm procedure is implemented in MATLAB software. The simulation results indicate the possibility of the method application practically, and it can operate online and automatically for various networks. Besides, it can select only one coherence setting for the synchronization assessment, and alter the setting according to the prevailed conditions of the networks. In addition, it is considered an integrated scheme which combines both synchronizing and protection functions. Moreover, it offers a new design of relay operating characteristics to differentiate between the synchronization and non-synchronization operation. Consequently, the synchronizer transmits a closing command to the intended CB, yet stays idle under contingency events.