Research Of Cathodic Protection In Power System Grounding Grids

Grounding grids, a fundamental part in power system, is very vulnerable to the corrosion damage caused by soil. When corrosion is severe, grounding device including grounding wire and grounding conductor may quickly get thinner or even broken, which could force the grounding resistance to increase and make those grounded equipments become inadequate grounded. In this situation, incidents might easily occur, endangering the power system and personnel. Therefore, anticorrosion of grounding grids is of great significance.Cathodic protection is an effectual way of protecting buried metal structure from corrosion. It consists of two methods: sacrificial anode and impressed current. The former has already been widely used in grounding grids anticorrosion project in power system, while the latter's application in grounding grids is still underway.A scheme of grounding-grid cathodic protection system using the method of impressed current is discussed in this dissertation. Two aspects of the design are a cathodic protection power source ( SF-200-2 potentiostat ) and a network for centralized supervisal and control in which potentiostats are RTUs.SF-200-2 potentiostat is composed of the host circuit and the control circuit. The host circuit adopts a single-phase semicontrol rectifier and an LC filter, while the control circuit is an embedded system using an AT89C51 singlechip as the main controller. The cathodic protection system contains bottom networks based on CAN bus and upper networks making use of SPDnet.Conclusions reached from testing experiments are that SF-200-2 potentiostat performs well because of its high precision, stability and convenience, while the cathodic protection system could promote the automation degree of the grounding-grid anticorrosion project.