| With the increasing scale of power system,the structure of power grid becomes much more complicated such that the system fault accident is more and more serious.In recent years,several times blackouts at home and abroad have caused enormous economic losses and resulted in adversely social effect.At the same time,the implementation of the “Emergency Disposal,Investigation and Settlement Regulations of Electrical Safety Accidents",so called Decree No.599,sets new requirements and standards for power system reliability,therefore,the study of power system reliability evaluation method based on accident risk has both theoretical and practical value.Two transmission system reliability evaluation methods considering electrical safety accidents are proposed in this thesis,which are suitable for different application scenarios,and more comprehensive accident risk indices are obtained.To calculate grid topology loss risk based on accident level,fault set research strategy considering the influence of the electromagnetic loop network on the reliability is suggested.Meanwhile,unreliability of high-voltage substation according to accident risk is taken into account while calculating reliability of low-voltage power grid;The model of evaluating electric safety accident level is established,and the influence of load distribution on the system accidents risk is considered according to the factors such as multi-voltage level and grid partition structure;The reliability of the system is calculated by the min-cut method,and the weakness of the grid is analyzed according to the reliability index.To calculate the static reliability considering of electrical safety accidents risk for transmission system,the system states are selected by analytic method,and “curse of dimensionality” is alleviated by fault multiplicity truncation;The PSASP is invoked to analyze the system power flow,and identify the overloaded components by current constraints;The distributed load shedding strategy based on power flow sensitivity is put forward to correct the system state and the order of nodes participating in the power adjustment is selected based on sensitivity information in order to minimize the load shedding,the load shedding scheme with optimal accident rating can be obtained by averaging the accident level in each region.Algorithms for the above two methods are implemented,and the correctness and effectiveness of the proposed method are proved by taking the actual system of Qinghai Province and CEPRI-36 system as examples. |
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