Research On The Optimal Allocation Of Distributed Generation And Electric Vehicle Charging Stations Under Interactive Environment

With the gradual exhaustion of fossil fuels(e.g.petroleum,coal and natural gas)and severity of environmental crisis(e.g.acid rain,smog and global warming),the distributed generation technology that employs renewable energy(e.g.wind energy,solar energy,hydroenergy and biomass energy),as well as the electric vehicle industry that helps to electrify traditional transportation,has attracted rapidly increased attention in recent years,and is becoming the research hotspot of power industry.Meanwhile,along with the continuous improvement in the intelligence and informatization of power system,the relationship between elements in modern distribution system tends to be closer than before,and their corresponding interaction becomes very frequent,which in consequence leads to a series of advanced technique concepts,novel control methods and new operation scenarios.Under this emerging interactive environment,whether distributed generation(DG)and electric vehicle charging stations(EVCSs)are properly allocated would directly impact the dispatch strategy and operation state of distribution systems,and subsequently brings about further influences to the economic and environmental benefits of the integration of DG and EVCSs.Based on this background,some new circumstances and trends in modern distribution systems,as well as their influences on the planning and operation of DG and EVCSs are studied in this dissertation.Furthermore,the optimal allocation methods under interactive environment are deeply investigated for determining the proper installation sites and sizes of DG and EVCSs.The main contents of this dissertation are as follows:(1)Considering the fast reactive power response characteristic of photovoltaic power plant,an optimal allocation method of DG is proposed.With more and more sensitive loads integrated into distribution systems,as well as the novel concept of PV-STATCOM that utilizes photovoltaic(PV)inverter as STATCOM to provide fast reactive power compensation,a weighted voltage support ability index(WVSAI)based on sensitivity analysis has been proposed in this dissertation to quantify the influence of PV power plant on sensitive load nodes' voltage recovery efficiency under emergency states.Then an optimization model is constructed to determine the optimal allocation schemes of DG,where the multi-state theory is employed to process the uncertainties of DG outputs and the proposed WVSAI is properly considered.Finally,an exact second order conic relaxation is adopted to make the constructed optimization ideally convex and easily solved.(2)An optimal allocation method of EVCSs comprising multi-types of charging facilities is proposed.Along with the development in the electric vehicle charging technology,multi-type charging facilities with various charging power tend to appear in one EVCS,which brings significant influence to the spatial and temporal distribution of electric vehicle loads.Based on this phenomenon,an optimization model is proposed in this dissertation to determine the optimal allocation schemes of EVCSs with multi-types of charging facilities.Meanwhile,to describe the mutual influence among multi-type charging facilities and process the derived scenario-based constraints,a two-step equivalence is proposed and applied,which transforms the scenario-based constraints into deterministic ones.Finally,the proposed optimization model is exactly relaxed by second order conic relaxation,and tested on a coupled geographical-electrical system that derives from practical urban areas in Jiangsu.(3)Taking account of the spatially dispatchable characteristic of electric vehicle charging demands,a coordinated allocation method of DG and EVCSs is proposed.With the popularity of real-time navigation technology,EV charging demands in some extent are becoming dispatchable ones within a certain geographical distance,which significantly impacts the spatial distribution of electric vehicle loads.Based on this phenomenon,an optimization model is proposed in this dissertation to determine the coordinated allocation schemes of DG and EVCSs,where the spatially dispatchable characteristic of electric vehicle charging demands is thoroughly considered.To be detailed,the proposed optimization model includes a sub-optimization issue concerning the spatial dispatch schemes of electric vehicle loads,and the linearized Distflow equations are used to represent the relationship among system state variables.Finally,a coupled geographical-electrical system is employed as the test system to verify the proposed optimization model.(4)A coordinated allocation method of DG and EVCSs under unidirectional/bidirectional V2 G environment is proposed.With the development of vehicle-to-grid(V2G)technologies,electric vehicle loads in distribution systems are becoming temporally controllable resources and enabled to provide a lot of ancillary services(e.g.peak power shaving,voltage regulation,spinning reserve and so on),which effectively relieve the negative effects caused by the randomness and intermittency of renewable energy.Based on this phenomenon,an optimization model is proposed in this dissertation to determine the coordinated allocation schemes of DG and EVCSs,where the V2 G functions of electric vehicles are properly considered.To be detailed,the proposed optimization model includes a sub-optimization issue concerning the charging scheduling of electric vehicles,and the linearized Distflow equations are used to represent the relationship among system state variables.Finally,the proposed optimization model is tested on a coupled geographical-electrical system that derives from practical urban areas in Jiangsu.