Research On Distribution Network Optimization With PHEV By Interval Algorithm

With the oil resource depletion and the global environment deterioration, thedevelopment of the electric car having the characteristics of low carbon, energy savingis an inevitable trend of realizing the sustainable development of human society.However, the electric vehicle charging behavior has strong randomness, large-scaleelectric vehicles charging behavior would cause great shock in both time dimension andspace dimension to the power system. To weaken the influence of the impact on thesystem, there should be some adjustment to the operation mode of the distributionnetwork. Therefore, this article focus on electric vehicles charging optimization schemebased on time dimension, space dimension and time-space dimension.First of all, in order to accurately describe the uncertainty of electric vehiclecharging load, research is based on interval analysis method replacing the traditionaldeterministic analysis method. With the support of the interval analysis, interval-basedforward-backward sweep method, interval-based branch exchange reconfigurationalgorithm and interval size comparison method are deduced respectively as thefoundation for subsequent optimization research.Secondly, do research on the charging capacity of the electric vehicle in timedimension. To avoid the electric vehicle charging load overlapping with the networkpeak load, this paper proposed a charging time limit capacity optimization scheme. Theoptimization scheme helps to improve power grid load curve and reduce the chargingcost by limiting the capacity of each charging station with satisfying the voltage offsetsconstraint of the network. For fully consideration of the electric vehicle chargingrequirements, this article introduces the network loss sensitivity and the customerdensity of the charging station as references for optimization, the final result shows thatthe scheme can reduce the adverse effect of the electric car charging effectively.Thirdly, according to the study on the influence of the system with different kindsof distributions of the electric vehicle charging load in space dimension, aninterval-based dynamic reconfiguration scheme is proposed to improve the networkoperation condition by changing the network topology and the load distribution. Theoptimization scheme takes the minimization of loss as objective function to optimal thesystem’s structure under the security constrains by time, and then judge the timesequence is whether merged with a period before or after following the ascending orderof the dynamic parameters, repeat the calculation until the final result is satisfied withthe switch constraints. The results proved that the scheme can optimize the operationmode of the system effectively without impacts to the electric vehicle owner.Finally, considering the influence of the electric vehicle grid charging in both of time and space dimensions, this paper proposed a time-space combination optimizationscheme based on interval algorithm. The optimization scheme use the connectionbetween the electric vehicle charging capacity in time dimension and the optimaltopology in space dimension as the foundation, take the minimization of the networkloss curve mean and volatility as the objective function, calculate the limit capacityscheme and reconfiguration scheme joint iteration repeatedly to obtain the best optimaloperation mode in time and space dimension. Final result shows that the scheme canoptimize both the voltage curve and the system loss curve, when compared withindependent optimization of time or space dimension, the time-space combinationoptimization scheme has better results.