| Nowadays,under the background of the profound electric power system reform and the increasingly open electricity market,the arbitrariness of power flow in the power transmission channel increases as the supply and demand sides can use the transmission network equally and undertake free bidding,the power flow randomness in the power transmission channel increases,so the possibility of transmission congestion increases dramatically,and the problem of transmission congestion becomes more and more prominent.With the rapid development of wind power industry in China,after the large-scale wind power grid connected to the network,the randomness of its output has put forward a new challenge to the management of transmission congestion in the power system containing wind farms.Therefore,it is of great practical significance to reasonably formulate a day-ahead dispatching plan for power transmission systems containing wind farms to cope with transmission congestion.Conventional transmission congestion is generally alleviated by network reconfiguration,adjusting FACTs equipment or redispatching generator output,and with the rapid development of smart grid and communication technology,effective utilization of demand side response resources become a new way to solve the problem of transmission congestion.In this paper,the problem of the participation of demand side response in the day-ahead transmission congestion management is intensively studied,and the influence of the wind power and demand response uncertainty on the transmission congestion management is special concerned.The design of the optimal access point for contracting,different types of demand side response strategies,the day-ahead transmission congestion management model and solution method considering the uncertainty of wind power and demand side response are studied.The research results indicates that the transmission congestion management method considering the influence of wind power and demand response uncertainty can effectively reduce the transmission congestion management cost,lighten the burden of generators for rescheduling resources at the same time,and ensure the safe and economic operation of power system and the fairness and efficiency of electricity market.A new decision-making method for the optimal location of the demand side response project is proposed in the paper,aiming at the problem to decide where the demand response project implements can achieve the optimal effect of transmission congestion management.The two-layer stochastic dynamic available transmission capacity optimization model is constructed,and different short-time wind power fluctuation scenario are selected to take into account of wind power output uncertainty.The lower optimization function is a day-ahead dynamic economic dispatch,and the upper level is to make the power output maximum in the power generation area.The two-layer model is converted with the KKT condition to a single layer optimization problem with equilibrium constraints to solve.The stochastic ATC value of each time period can be calculated at one time,and then the value and fluctuation of the two evaluation indexes of available power supply capacity(LSC)and locational marginal price at the load nodes in the power receiving area can be obtained.The results of single and multiple demand response projects show that the proposed model and evaluation index are superior,and can provide a reasonable data support for effective decision-making of the optimal alternative nodes for implementing demand side response.In order to solve the optimal contract quantity problem of demand response(DR)project involved in the transmission congestion management,a two stage stochastic optimal scheduling model with demand response is first constructed to obtain the optimum quantity of demand response the system operator(ISO)expected.Consider the time of use price based DR and incentive based DR implement in two-steps,and the load reduction and load transfer calculation method of each contract DR is given.On this basis,a design method of price and incentive mechanism for time of use price based DR and incentive based DR considering multi-stakeholder gambling is further proposed.A multi-objective optimization model,in which the multi interests of load aggregators and users are considered,is built to design the price mechanism of time of use price based DR,a multi-objective optimization model with the least amount of compensation expenses paid by the load aggregator to the user and the maximum of the DR contracted amount nearest to the ISO expected DR amount is set up to design the incentive mechanism of incentive based DR.The multi-objective optimization algorithm is used to solve the each problem.The calculation results show that the price and incentive mechanism of DR proposed in this paper can reasonably and effectively guide the users to participate the demand side response,make the actual response value of DR close to the ideal value of scheduling,enhance the information transfer between the system operators,the load aggregators and the users in the power market environment,and will help promote multilateral win-win benefits.Aiming at the influence of the uncertainties of wind power,load and demand response on transmission congestion management,a new power system transmission congestion management model based on stochastic chance constraints is proposed in this paper.Three chance constraints of transmission lines without congestion,reliable load power supply,high wind power utilization are constructed and applicable to the day-ahead economic dispatch under the non-regulated power market environment.Based on the assumption that the uncertainty of wind power,load and demand side response obeys the normal distribution,the probability distribution function of random variables is integrated,and the chance constrained optimization problem is transformed into an equivalent deterministic optimization problem by the dichotomy,and the optimal scheduling scheme is obtained by using the original coupled interior point method to solve the congestion management model.Further,the transmission congestion management model based on DC optimal power flow,unable to consider transmission network loss and the scheduling scheme may not be able to fully meet the chance constrained condition,is improved,the model of AC flow iteration are introduced to consider the transmission losses,and the multi-period probabilistic flow calculation and the transmission line congestion risk value index are used to verify whether the scheduling scheme obtained by the proposed model satisfies the chance constraints.The calculation results and analysis show that the proposed transmission congestion management model can effectively deal with the influence of uncertainties in the system,and make the daily scheduling scheme has strong applicability.In order to solve the problem that the probability distribution function of wind power,load and demand response prediction error may be uncertain,a distributiobal robust optimization method from mathematical field is introduced,which transforms the above transmission congestion management model into a semi-definite programming to solve.This method can make transmission congestion management model applicable to wind power and load and demand response prediction error under any possible distribution.Further,the paper introduces the concept of dynamic line capacity into the management of transmission congestion,and studies the dynamic thermal stability rating(DLR)formulation as well as the the influence of uncertainties caused by various parameters in the external environment on the transmission congestion management,and proposes a new chance constraint(TDLCP)guaranting transmission line without congestion.Through the distributional robust joint optimization method,the model is transformed to a mixed semidefinite programming problem,and the optimization toolbox YALMIP and MOSEK are used to solve it.The results show that the proposed optimization method can make the transmission congestion management model more applicable. |
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