Breaking Over-voltage And Protection For66kV Dry-type Air-core Shunt Reactors

Dry-type air-core shunt Reactors can play a role in supplementing inductivereactance and balancing reactive power and limiting over-voltage, it is the keyequipment in the power system. In recent years, the burnout accident of dry-type air-core shunt Reactors happened frequently, The relevant Investigation have shown thatbreaking over-voltage is one of the causes of burnout accident. Investigation onbreaking over-voltage and protection for66kV dry-type air-core shunt reactors hasthe great significance.This paper analyzed the types and mechanism of breaking over voltage and theprotection method based on circuit theory and the method of connecting wire of66kV dry-type air-core shunt reactors and the working characteristics of SF6circuitbreaker. Models of the SF6circuit breaker and the dry-type air-core shunt reactor areestablished, and a three-phase circuit is built, and simulation analyses the breakingover-voltage by ATP-EMTP software. Through combining with the simulation resultanalyzed of the influence factors of breaking over-voltage, described the generatingconditions of reignition overvoltage and the cutting-off condition of SF6circuitbreaker. Analyzed the research on the protection methods, put forward a new kind ofprotection circuit, designed a set of protection device, and verified the reliability ofthis protection device through experiment.The research results show that circuit breaker will be no reignition and manydifferent reignition, there are chopping current over-voltage and reignitionovervoltage on the reactors. Chopping current value and the start breaking difftimeis influence factor for over-voltage. Chopping current over-voltage amplitude valueincreases with the chopping current value, reignition overvoltage increases with thestart breaking difftime. Combined protection methods which proposed in this papercan make up for the insufficiency of arrester and the RC protection device. Theprotection device which designed according to combined protection methods have been through the reliability experiment, laid the foundation for the site feasibilityexperiment.