Research On State Maintenance Strategy Of Active Distribution Network With Distributed Generation

With the rapid development of power system and strong smart grid,the scale of the power grid has been increasing,and the number of power equipment has increased dramatically,condition-based maintenance has become an effective way to optimize equipment management under the goal of efficient operation of power companies because of its strong pertinence,high efficiency and good economy.At the same time,social development makes people's demand for electricity continue to grow,and the global energy crisis is intensifying.The new energy generation mode has gradually attracted the attention of people,and the penetration of distributed generation in distribution network has been increasing year by year.With the continuous improvement of the grid capacity of distributed generation,the active distribution network is gradually replacing the traditional distribution network.Therefore,it is necessary to study the condition-based maintenance strategy of the active distribution network with distributed generation.The main contents of this paper are as follows:(1)Study the condition evaluation system of the equipment in distribution network,and establish the condition evaluation model of equipment on the basis of basic score considering the enlistment age and family defect,and get the relationship between the condition of the equipment and the index of well-being.By using the improved EA failure rate empirical formula and the reliability evaluation method,the formula of the equipment fault probability calculation is obtained.At the same time,considering the aging effect of the equipment and the repair effect of maintenance,the probability of failure in the study period is reasonably predicted.The state enumeration method is used to select the state of the system,and the aftereffect of the equipment failure mode is predicted and evaluated by the risk assessment technique.(2)The influence of the distributed generation on the reliability and economy,the requirements of the islanding operation of the distributed generation and the three typical models are summarized according to the characteristics of the active distribution network.On this basis,the isolated island running strategy of distributed generation is analyzed.First of all,the distributed generation is taken as the center,and the predicted power as the radius,and all possible power supply paths of the distributed power supply are determined by the breadth first algorithm.Then,considering the magnitude and magnitude of load power,we set weights for the edges and nodes in the power round connected graph.We use the improved prim connected graph search algorithm to search the power tree in the power circle,and determine the scope of islanding.Finally,by using the improved PG&E69 node power distribution system,an example analysis of isolated island division is done.(3)The status maintenance strategy of distribution network with distributed generation is proposed.The total objective utility function of maintenance decision-making is established from three aspects of maintenance cost,distributed generation operation benefit and risk assessment under the constraints of power grid security,maintenance resource,maintenance time and island operation.Among them,the operation benefits of distributed generation include the power supply and environmental benefits generated by the isolated island operation of distributed generation when the network is being maintained,and at the same time,considering on-grid price of distributed generation is higher than others,it is necessary to deduct the cost of power purchase.Risk assessment includes system failure risk and maintenance risk,and it is evaluated from two angles of equipment loss and system power loss taking account of the isolated island operation strategy.An improved particle swarm optimization algorithm is proposed to solve the total objective utility function of maintenance strategy and optimize the maintenance time and maintenance mode of all the equipment that need to be maintained.The model is verified by the IEEE RBTS bus2 distribution network reliability test system added with distributed generation,and the validity and superiority of the state maintenance strategy model are proved.