Superiority of PSO Relay Coordination Algorithm over Non-Linear Programming: A Comparison, Review and Verification

Over Current Relays (OCRs) and Directional Over Current Relays (DOCRs) are widely used for the radial protection and ring sub transmission protection systems and for distribution systems. All previous work formulates the DOCR coordination problem either as a Linear Programming (LP) problem or as a Non Linear Programming (NLP) problem or as a Mixed Integer Non Linear Programming (MINLP) Problem or as a Mixed Integer Programming (MIP) problem using optimization techniques. In this paper, a Modified Particle Swarm Optimization (MPSO) technique is discussed, reviewed and verified for the optimal settings of DOCRs in power systems as a NLP problem. The paper also compares MPSO algorithm with General Algebraic Modeling System (GAMS). The calculation of the Time Dial Setting (TDS) and the pickup current (Ip) setting of the relays is the core of the coordination study. Recently PSO is considered as realistic and powerful solution schemes to obtain the global or quasi global optimum in optimization.