Unidirectional Co-control Of Source-grid-vehicle System For Wind Power Absorption And Atmospheric Pollution Mitigation

With developments of economy and society,pressures on energy-saving,emission reduction and prevention and control of air pollution are increasing day by day.On one hand,emissions of air pollutant frequently exceed the environmental capacities of key human settlements,which greatly increases occurring probabilities of fog and haze events;on the other hand,although wind penetrations have reached up to a relative ly high level in China,the wind curtailment issue remains serious.Large amounts of wind energy require to be absorbed.In these backgrounds,the Chinese government has proposed an energy development plan of replacing oil with electricity by developing electric vehicle(EV)industry.Among all kinds of EVs,private plug-in EVs(PEVs)will possess considerable proportions in future.Thus,through dispatch and control managements,promoting ratios of energy generated from wind turbines among total volumes of energy used by PEVs and enhancing response capabilities of electric power source-electric power grid-EVs(abbreviated as source-grid-vehicle,SGV)systems to alerts of heavy air pollution are of great significance to implementing the development plan of electric energy substitution.This paper deeply studies the coordinated dispatch and control(abbreviated as co-control)issues of SGV systems(SGVSs)involving basic modelling,co-control mechanis m,decision methodology and security check and correction.The purposes are to absorb surplus wind powers in the grid,enhance efficiencies of SGVSs on mitigating air pollution in key human settlements,reduce technical difficulties and implementation costs of managing PEV charging load,promote SGVSs' reliability and scalability and avoid exposing PEV owners' privacies.Considering that distribution dispatch and automation systems in China cannot yet monitor information of individual PEV's charging behavior,this paper uses the idea of data mining-theoretical modelling-parameter identification to study the method of identifying characteristic parameters and the technique of counting and evaluating dispatch elasticity(DE)for natural aggregated charging loads(ACLs)of actual PEV fleets.For natural ACL,a data-mining method is proposed and an analytical calculation model is derived.Besides,a characteristic parameter identification model is built.DE of natural ACL is divided into two types and corresponding statistics and evaluation methods are separately proposed.Based on actual residential data,feasibilities of the data mining method and the parameter identification model are verified.Statistics and evaluation results of DE are analyzed.The proposed methodology does not rely on the collection of individual PEVs' charging behavior information.Thus,it will save corresponding costs of investment,operation as well as maintenance on information collection and data transmission systems,and protect privacies of PEV owners' charging behaviors.Identified characteristic parameters can be used to tune the coordination signal of charging load and evaluation results of DE index are able to reflect the potential capability of charging load taking part in the coordination program.To reduce technical difficulties and imple mentation costs of coordinating charging load resources,a unidirectional co-control mode is proposed for SGVSs.From the perspective of absorbing surplus wind energy and alleviating charging synchrony,a unidirectional co-control mechanism is designed to coordinate the temporal-spatial distribution of PEV charging load.Charging poles only require to receive the multi stochastic time-of-use pricing(MS-TOUP)information via one-way communication from the grid level and use a local response algorithm designed in advance to autonomously decide start charging times for individual PEVs.It is easy to bring the mechanism into the current power dispatch and control system in China.Noted that,the MS-TOUP is designed based on an idea that PEVs are divided into different groups and charging times are staggered among groups.A coordinated ACL model is built.A seasonal MS-TOUP parameter tuning model is proposed to help absorb surplus wind power in winter.The cheap tariff range of TOUP is identified.The mechanis m will help form steady complementary synergy between ACL and surplus wind power,and greatly mitigate the effects yie lded by the short sharp increment in feeder load.It will produce relative ly high benefits of security and economy.To increase flexibilities of absorbing surplus wind energy via PEVs and consider regulation requirements of distribution feeders,a short term co-control method is studied to coordinate the temporal-spatial distribution of PEV charging load.The method is based on the co-control mode that charging poles receive the MS-TOUP information via one-way communication,and autonomously decide PEVs' start charging times.The basic framework is designed for the co-control system.The local charging response algorithm and the coordinated ACL model are improved by carefully dealing with times when PEV owners schedule to departure home.On this basis,a day-ahead model is proposed to tune MS-TOUP parameters and a day-ahead algorithm is designed to check and correct MS-TOUP parameters.The proposed method will help form flexible complementary synergy in short-term time scale between ACL and surplus wind power,and meanwhile satisfy regulation requirements for feeders.The method will not rely on the power grid monitoring individual PEVs' information,and will aviod exposing privacy information of PEV owners.It is with well cost-effectiveness,high reliability and scalability.To enhance effic iencies of PEV charging load resources and coal-fired units on responding to the heavy air pollution whether alert in a pointed manner,the short term co-control method of a combined PEV and electric-thermal system is studied under the unidirectional co-control mode of SGVSs.A state of charge tiered pricing(SOCTP)scheme is proposed to lead PEVs to automatically decrease proper volumes of charging energy from coal-fired units that have high margina l effects on heavy air pollution.A novel idea,levying air pollutant tax from coal-fired units according to the spatial and temporal distribution of AQI,is proposed to promote utilization effic iencies of margin resources of environmental capacities.On this basis,a day ahead co-control model of a combined PEV and electric-thermal system is formulated by integrating SOCTP,MS-TOUP and novel emission tax.Case studies show that,the coordinated regulations of SOCTP,MS-TOUP and novel emission tax will enhance efficiencies of the combined PEV and electric-thermal system on mitigating air pollution in key human settleme nts.