A Single-Terminal Fault Location Method Using Hybrid PSO-GA Optimization and Distributed Parameter Line Modeling

Abstract

Correct and fast fault localization of high voltage overhead transmission lines is a primary need toward ensuring the stability and sustainability of present day power systems. The traditional methods of fault location such as impedance-based and travelling-wave methods are known to be limited by the following factors: sensitivity to fault impedance variations, reliance on synchronized multi-terminal measurements and expensive communication infrastructure. This paper proposes a new single-terminal fault location architecture that resolves these limitations by taking advantage of a special and deterministic post fault system state with neither long-range data nor inter-substation communication.

The algorithm proposed is based on a model of distributed parameter transmission lines, which is able to faithfully model the electromagnetic behavior of long transmission lines. Clark transformation is used to transform the coupled three-phase system to decoupled modal networks, which allow each of the sequence components to be analyzed separately. The native genius here is that the momentary operation window is strategically used wherein, the remote-end circuit breaker has cleared the fault, yet the local-end breaker is not activated. One effect of this short time interval is that the current at the receiving-end is zero, and so the fault location equation is completely deterministic and does not require the remote source impedance parameters.

The nonlinear objective function obtained is then solved with the help of a hybrid metaheuristic algorithm that combines Particle Swarm Optimization with a Genetic Algorithm. The combination takes advantage of the fact that PSO is very good at local exploitation and GA is very good at search exploration, which has the effective effect of avoiding premature convergence and guiding to the global optimum with high accuracy. The validity of the proposed approach is supported by thorough MATLAB/Simulink simulations that have been made on a real 400 kV, 239 km transmission corridor between Iraq and Iran. Evaluation of faults of various types, such as single line-to-ground, line-to-line, double line-to-ground, and three-phase faults, indicates that the hybrid PSO-GA technique can always provide significantly higher localization accuracy than the standalone PSO and non-iterative benchmark techniques without increasing the computation time (less than 0.5 seconds).