Reliability Analysis And Application Of Primary And Secondary System In Power Grid

Objective and quantitative evaluation of power system reliability can explore theweakness and point out a way for power system planning/optimization from the view ofimproving reliability, in order to achieve the goal of keep security, stability and reliability ofpower system operation. To avoid accidents and keep security, stability and economic,primary devices and its system of stable and reliable performance are not only needed,reliability of different levels of secondary systems are also put forward very high demand.Multiple cases of blackout wake the people: power system is a systemic project, includingprimary and secondary systems. For a long time, power system reliability evaluation cannotsatisfy the development of power system in the way of object richness, model fineness andevaluation efficiency. Particularly, with the development of economy and society of China,power system reliability evaluation is of the great practical significance and engineering value.For this reason, the dissertation discussed reliability analysis and application of primary andsecondary system in power grid, according to the new characteristics of primary andsecondary systems. The main work is as follows:Least square method is used to fit defect rate with respect to service life, based onvariance analysis and orthogonal design. It is found that service life of secondary device hasgeneral significant influence on the defect rate; in accordance to the features of secondarysystem and the defect laws, reliability indices of secondary devices are proposed; sensitivityanalysis of influencing factors contributed to optimum maintenance cycle indicateself-checking factor, overhaul success factor, protection failure rate affects most.Aiming at complexity and particularity of automation system, binary decision fault treemodel are built, combing fault tree analysis and importance factor. And the approach isapplied to evaluation the reliability of substation automation system. Sensitivity analysismethod is employed to explore the enhance measures of key devices redundancy. Theengineering cases validated the availability of the approach.As part of the modern power grid, digital substation is typical phased-mission system.Considering the reliability of secondary devices and communication system, fault tree modelof phased-mission system is proposed, achieved comprehensive reliability assessment ofprimary and secondary system. The engineering cases validated the availability of theapproach.The cloud theory based on the traditional fuzzy set theory and the probability theory haspotential to solve both of them at the same time. Therefore, operational risk assessment of regional power grid is proposed, which provides an uncertain transformation model betweensome qualitative concepts described by natural language terms and some quantitative valuesdistributions. The numerical results of Guangzhou grid typical operation mode demonstratethe practicability and maneuverability of the approach proposed.According to the characteristics of China south grid which is an AC/DC hybridtransmission system with ultra high voltage direct current transmission system, multi-infeedhigh voltage direct current, the weakness of original planned grid are found by reliabilityevaluation and sensitivity analysis. In order to improve the transmission capacity, strengthenelectrical contact between send and receive terminals, increase system stable level, theoptimization scheme is determined. The results show that the proposed optimization schemecan advance the transient stability greatly, and the optimization effect is very significant.