| Lightning is one of the strong convective weather, which is ferocious and easy to form disaster. Lightning is one of the major causes of outages in electric power system. The techniques of setting up reliability model of overhead lines and quantifying the impact of lightning on the distribution system reliability can be helpful to reduce the lightning storm impact on distribution system and build defense system. In this paper, predictability and defensiveness of distribution system lightning flash events are as guiding ideology. The reliability model is built considering the relationship of bad degree of lightning storm characteristic parameters and risk model of distribution lines under lightning storms. Risk measurement of distribution system may be obtained timely. At the same time, according to the annual lightning storm characteristic parameters feature, considering the type of insulators and intervals of arrester installation as constraint to build a design model of distribution lines.Based on extraction of lightning storm parameter characteristic variables and lightning fault mechanism of overhead distribution line, the overhead line time dependent failure rate model and repair time multi-stage probability model are built. The lightning flashover rate is given according to principles of electrical geometry model. Then failure rate and repair time model of lines is built based on lightning historical data, by using curve fitting and multilevel piecewise linear representation method. Case study analyzes the impact of terrain condition and insulation strength on line reliability.Based on lightning reliability model of overhead lines, the reliability indexes under lightning weather is presented and the reliability assessment method of distribution system is proposed by applying the model above to failure mode and effect analysis(FMEA). Based on forecast information under lightning storms, lightning process is divided into several periods to evaluate the reliability of distribution system. Customers can timely obtain the risk measurement of distribution system. The case study evaluated the reliability in each period under different terrain condition and different insulation strength, which can be used to provide quantified decision criteria for distribution system planners and operators.Aiming at the strong lightning area and considering the annual lightning storm characteristic parameters feature, the annual reliability model of overhead distribution line is built. This paper takes life cycle cost of distribution system as objection function and type of insulators and intervals of arrester installation as constraint to build a design model, and uses genetic algorithm to solve this model. Case studies on the RBTS-BUS2 test system and a practical EDN show that planners can get the risk of overhead distribution line by lightning strength information and obtain the optimization model with reliability and economy. |
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