Region-partitioned Fault Diagnosis For Grounding Grid Based On GPSO Algorithm

The grounding grid is the unity of working grounding, protective and lightning grounding, which is vital for the safety protection of personnel and electrical equipment, as well as maintaining stable operation of power system. At present, the performance of grounding grid is judged by measuring the value of grounding resistance on-site, and a large area of land is excavated with blindness, in order to carry on the investigation. In this paper, a new diagnostic method is proposed, without power off and large area excavation, to make judgments of corrosion failure and fault location. It is meaningful to detect hidden faults, in order to prevent the damage caused by bad grounding.Firstly, through the ground lead above ground, the grounding grid is equivalent to a multi-port resistive network. The mathematical equation model, establishing the relationship between port resistance variation and branch resistance variation, is to set up by the application of circuit theory and Tellegen’s theorem.Secondly, to improve the reliability of diagnosis results, the grounding grid’s region is partitioned and the network topology is simplified to obtain the intrinsic grounding grid by hierarchical simplification. In accordance with the value change of intrinsic branches before and after failure, the fault regions are judged by tracing from the intrinsic grounding grid to the upper layers. The simulation results effectively demonstrate the practicability and accuracy of this method.Furthermore, a novel diagnostic method based on Glowworm Particle Swarm Optimization(GPSO) algorithm is proposed in this paper to diagnose large-scale grounding grid.By optimizing the fault diagnosis equations model, this method converts it into the equivalent optimization problem. On the basis of Glowworm Swarm Optimization(GSO) algorithm and Particle Swarm Optimization(PSO) algorithm, as shown in the example, this method has advantages such as high precision, high speed and high stability.Based on those models, common fault diagnosis system of grounding grid has been designed, which is consisted of measuring instrument and diagnosis software. The effectiveness and practicality of the system is verified by field experiments, which can guide the field maintenance.