Network Loss Evaluation Of Power System Considering Participation Of Electric Vehicles In Frequency Regulation

The emergence and development of electricity demand response technology has led to a role shift for traditional users,which is beneficial to the dynamic coordination of resources between the supply and demand sides of the power system.Electric vehicles(EVs)as demand-side resources have attracted extensive attention,because of the steady advances of vehicle-to-grid(V2G)technology.On the one hand,large-scale EVs energy storage can be as a large power source for power grid.Coupled with the rapid regulation,EVs can provide good auxiliary services for the power system.On the other hand,large-scale EVs integrating into power grid will change the network flow and the network loss,and then the economy of power systems is affected.Therefore,the main work of this paper is to study the influence of EVs participating in frequency regulation on system network loss,so as to provide a certain theoretical basis for carrying out loss reduction and energy-saving operation as well as reasonably implementing power grid planning,in the case of large-scale EVs integration into power grid.The mainly studies in this paper as follows.Firstly,traditional frequency regulation and the problems need to be solved are introduced.And then the development of V2G technology and the feasibility of EVs participating in frequency regulation are described.Besides,the research status of power system network loss assessment is summarized.Furthermore,the framework of the participation of EVs in automatic generation control(AGC)is established on the basis of the introduction of the control mode of EVs participating in frequency regulation,which lays a theoretical foundation for the following research and analysis.Secondly,the influence of EVs integration on system network loss is analyzed in principle,and then an evaluation method of system loss is proposed considering the participation of EVs in AGC.Based on the control framework on EVs participating in AGC control,the nodal capacity of EVs for regulation is estimated according to EVs’information such as charging/discharging power,and the nodal power distribution is proposed for EVs to participate in AGC.Besides,the system network loss is modeled and used to evaluate the system network loss with EVs’participation in AGC.The results show that,compared with the generator sets participating in AGC control,EVs participating in AGC control is more conducive to maintaining the system network loss at a certain level without wind power,and has a greater impact on the system network loss with wind power.Then,a network loss assessment scheme considering the optimal participation of EVs in frequency regulation is proposed.According to the framework on EVs participating in frequency regulation and the nodal capacity of EVs for regulation,an optimal distribution model of EVs participating in frequency regulation considering the marginal price of system nodes with the goal of minimizing system cost is established.The barrier function is introduced into the model to make the EVs and generators match reasonably and conform to the reality.System network loss is obtained through power flow calculation and then the system network loss is evaluated.The results show that,compared with the traditional generator participating in frequency regulation,in the case of without wind power,when ARR_t>0,the proposed optimal distribution method of EVs participating in frequency regulation not only can reduce the network loss of the power system but also ensure the economy;when ARR_t<0,although the network loss of the power system cannot be reduce,it does not significantly increase and can guarantee the economy.With high penetration of wind power,the proposed method not only can ensure stable and economic operation,but also maintain system network loss at a certain level by coordinating EVs and generators.Finally,the whole paper is summarized and the further work is carried out.