Research On Distribution Network Frame Planning And Optimal Operation Of Active Distribution Network

In recent years,the accessing of many distribution generation(DG)and energy storage(ES)have made the traditional distribution network(DN)more flexible and also increase the complexity of distribution network framework.It proposed new challenges.Active distribution network with its active control and active management mode has been paid attention by people gradually.The increasing demand for high energy and the high demand for power quality will accelerate the expansion planning of distribution grids and the new round of grids planning led by active distribution networks is imperative.First of all,as the foundation for the study of distribution network,especially for the study of network planning,the network topology analysis is essential.In this paper,it propose a method of network connectivity named Node Associated Island Consolidation and an example is given.Based on the method of connectivity,this paper introduces the detection methods of ring network and isolated island in distribution network and the processing method of "pseudo ring network" in distribution network.Secondly,this paper takes economy as the optimization goal,and carries out the grid planning of the active distribution network.The planning adopts the nested optimization of the upper and lower level.The upper level uses the genetic algorithm to optimize and select the original distribution line and the new extension line.The objective function is that the annual comprehensive cost of the network includes the annual value of investment and operation cost in upper grid and annual cost of lower level optimization.The upper level will filter out the radial connectivity of the network architecture and send to the lower level.It use multi-objective particle swarm optimization(MOPSO)based on the upper grid to optimize the location and capacity of DG and ES.The annual cost and the voltage deviation rate are two-objective functions.After optimization,a set of Pareto optimal solutions are obtained.Based on the fuzzy theory,a compromise solution that takes into account the two target values is proposed as the optimal solution to return to the upper level and the upper fitness function is calculated.The upper and lower levels are repeatedly delivered to finally optimize the optimal active distribution network grid plan.In the lower level planning,two methods,the sequential scene method and the scene compression method,are used to deal with the uncertainty of the wind,solar and load.The same number of scenes are constructed by the two methods,and two kinds of statistics are calculated and compared under the same number of times.Using the full-timing method as a comparison standard,The final cost,line configuration,and installation capacity of the DG of the two method are simulated on the IEEE 33 node expansion system.Lastly,it is about the study on optimal operation for fault reconstruction of active distribution network.According to the objective function and constraints of fault reconstruction,a hierarchical optimization idea is put forward to ensure that the network switch combination with the minimum interruptible load and the minimum network loss can be selected under the condition of the largest load.Finally,step up the idea of hierarchical optimization and carry out an example analysis.