| After access to distributed generation(DG),it has a profound impact on the structure and operation of power system.Taking into account the randomness of DG brings new problems to service restoration.This paper focuses on the service restoration problem of step-down substation bus failure,and the following work is done:(1)In order to solve the local convergence problem in genetic algorithm,a topology search method is proposed.When the local optimal solution occurs,the range of power supply is extended to the losses region in the charged area with residual power.This method can effectively improve the convergence rate of the algorithm.(2)According to the randomness of main power supply and the DG output,the multi-state model of power output is established based on the multi-state theory.Considering the impact of different time division on service restoration,the multi-state model of time division is established,constructs the multi-state model of divided-period first,during each of which,the multi-state model of power resource output is constructed according to the predicted value of output of main network and DG.The method transforms the uncertainty state of the power supply into multiple deterministic states,which effectively reflects the randomness of time division and the power output.(3)The multi-period service restoration model is built up based on the chance-constrained programming,taking the switching state as the optimization variable and the minimum loss of equivalent load during the entire period of recovery as the objective function.the model is solved with the genetic algorithm and the effectiveness of the model and the solving method in this paper is confirmed by the case of the IEEE33 distribution network and PG&E69 network.Example shows that the service restoration process is considered more comprehensively,and the best solution is the applicability of time division and the randomness of main power supply and the DG output. |
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