Coordinate Network Reconfiguration And Demand Response To Optimize Distribution System Operation

Historically,the construction of distribution systems in China is far behind that of transamission systems,leading to the problems of weak network structure,low coverage rate of automation devices,and insufficient capacity of absorbing distributed generation.Although the distribution systems optimization problem has been widely studied,there still exists some problems to solve concerning theoretical approaches and practical methods.Therefore,the paper studies how to achieve the goal of optimizing distribution systems un-der the premise of ensuring system stability and security,considering distributed renewable energies and demand response.From the perspective of network reconfiguration,the eco-nomic analysis of distribution systems reconfiguration and looping distribution systems us-ing fault current limiters has been conducted.From the perspective of demand side,propose the customer coupon demand response program considering multiple load aggregators.Fi-nally,propose a risk-constrained stochastic method for balancing wind power by coordi-nating network reconfiguration and demand response program.Major works included four parts,described as follows:(1)Switches that have actively participated in the reconfiguration process are identi-fied as sensitive switches.These are sectionalizers that are to be substituted by smart(re-motely controlled)switches.A method is proposed to determine the optimal numbers and locations of upgraded sectionalizers.Greater energy cost reductions are achieved when system reconfigurations are carried out with higher frequency.However,this reduction is associated with large initial investment cost on switch upgrades.Studies have been con-ducted on hourly,daily,weekly,monthly,and seasonal reconfiguration plans,based on the 8760 hourly loads of a year.According to the results,two economic indexes:total savings and return on investment are used to determine the optimal switching frequency.The results reveal that the proposed method can bring great economic benefits.(2)A new network structure is proposed to solve the problem of overcurrent leading by distributed renewable energies.The structure loops primary distribution systems using Fault Current Limiters(FCLs).FCLs diminish the short circuit current and the looped op-eration significantly reduces the active power loss while simultaneously increasing reliabil-ity.With this technique,there is no need to upgrade the upstream circuit breakers and set-tings of protection devices when operating in a loop.It is demonstrated that there is a tradeoff between benefits(reliability improvement and loss reduction)and acquisition cost of FCLs.A comprehensive economic analysis based on optimization methods is conducted to determine the number and location of FCLs in a typical system considering costs and benefits.The results are compared against conventional distribution system reconfiguration.The comparison makes evident the superiority of the new method.(3)Discusses the feasibility of load aggregators based customer coupon demand re-sponse considering power losses.The interdependence of the locational marginal price and the demand is modeled by an artificial neural network.The effect of multiple load aggrega-tors participating in customer coupon demand response is also investigated.Because load aggregators satisfy different proportions of the objective,a fairness function is defined that guarantees that aggregators are rewarded in correspondence with their participation towards the objective.A dynamic coupon mechanism is designed to cope with the changing nature of the demand.To validate the effectiveness of the method,simulations of the proposed method have been performed on a real heavily-meshed distribution network in this paper.The results show that customer coupon demand response significantly contributes to shav-ing the peak,therefore,bringing considerable economic savings and reduction of loss.(4)Discusses the potential of providing wind power balancing service in real-time electricity market by coordinating reconfiguration technique and demand response.Under demand response program,the coordination of thermostatically controlled load model and battery energy storage has been analyzed.The risk of exceeding customer comfort limit is measured by conditional value-at-risk(CVaR)index.Due to the time interdependence of wind power,a Markov Decision Process(MDP)formulation in combination with dynamic programming is adopted to solve the multi-stage stochastic optimization problem.The re-sults show that coordinating reconfiguration technique and demand response can signifi-cantly contribute to compensating for the forecast error of wind power,therefore,bringing considerable economic savings on balancing cost in real-time electricity market.