Capacity Assessment Of Distribution Networks Accept Charging Loads For Electric Vehicles And Research On Loss Reduction Of Orderly Charging

As a new type of load,electric vehicle(EV)has strong randomness in its spatial and temporal distribution.With the rapid growth of the ownership of electric vehicles in China,the phenomenon of load "peak on peak" will occur when large-scale electric vehicles are disorderly charged.The new load peak will have a great impact on the safety and economy of distribution network operation.Therefore,this paper carried out the research on the assessment of the charging load capacity of electric vehicles accepted by the distribution network and loss reduction by orderly charging.Considering that large-scale EV charging will have a negative impact on the protection of distribution network,this paper proposes a method to assess the capacity of distribution network to accept EV charging load considering the sensitivity of protection.Firstly,charging loads of different types of electric vehicles are modeled and simulated by Monte Carlo simulation method.Further,on the basis of taking system capacity and node voltage deviation as the limiting conditions of EV charging load acceptance capacity,the sensitivity-of overcurrent protection is considered,the capacity of distribution network to accept EV charging load is analyzed,and the assessment steps are given.The improved IEEE-33 node distribution network is used to simulate four different cases,and the maximum access scale of EVs in each case is obtained.Aiming at the partially disordered and partially ordered EV charging scenarios in the actual distribution network,this paper proposes an orderly charging optimization method with partial disordered charging.In the case of partial ordered charging,a mathematical optimization model aiming at minimizing the total network loss was established,and the particle swarm optimization algorithm was used to solve the model.The improved IEEE-33 node distribution network is used for example simulation,and two different simulation cases are set,and the comparison between all disordered charging scenarios and partial disordered and partial ordered charging scenarios is made.The results show that the method proposed in this paper can effectively reduce the network loss of the system,and at the same time achieve peak clipping and valley filling,smooth load fluctuation and reduce the charging cost of car owners.