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Fault trip of overload line transfers the power flow to other lines in the associated transmission section, which results in interlocking tripping accident. The key to prevent cascading tripping accidents is to quickly formulate a reasonable and effective power flow control strategy to eliminate line overload. In view of the defects of low accuracy of sensitivity method and too much calculation of optimization method, a double-layer optimal power flow control strategy of transmission section based on positive and negative comprehensive sensitivity is proposed. Considering the overall regulation effect of nodes on overload and heavy load line power flow, the positive and negative comprehensive sensitivity index is proposed, and then the power flow control strategy is quickly formulated by double-layer optimization method. In order to prevent the surge of computation caused by too large search space, a multi-objective selecting optimization model of the first layer scheduling nodes is established to optimize the scheduling nodes involved in the adjustment. On this basis, the second layer power flow regulation optimization model is constructed to obtain the accurate output adjustment of the scheduling nodes. The above model realizes the accurate dispatching of power flow out of limit on the transmission section. The simulation results of IEEE 39-bus system and a provincial power grid verify the rapidity and accuracy of the proposed method.

Equipment maintenance decision is a very critical technology in power grid asset management. The traditional maintenance decision focuses on the analysis of the operation performance of the equipment itself, but lacks the analysis and description of the fuzziness of power equipment outage parameters. Therefore, this paper establishes the reliability assessment model based on equipment health condition monitoring, which makes the maintenance decision transition from equipment level to system level, and the fuzzy mathematics theory is introduced to establish a model describing the fuzziness of equipment failure rate parameter to make system reliability assessment and equipment maintenance decision scheme. Firstly, this paper proposes a fuzzy failure rate model of power transformer based on condition monitoring. Then the fuzzy parameters are combined with the conventional probabilistic reliability assessment method to establish the fuzzy probability hybrid reliability assessment model of the transmission system, and the fuzzy maintenance reliability benefit index is defined and deduced. Finally, a maintenance strategy of transformer based on fuzzy probability hybrid reliability assessment and fuzzy set theory is proposed, and the case study is carried out on a regional power grid in East China. The results show that the proposed model provides an improved maintenance strategy of power equipment. [ABSTRACT FROM AUTHOR]