Research On Available Transfer Capability Of Power System In The Market Open To Both Supply And Demand Sides

With easier access to electricity market,the interest objects of electric power system are gradually diversified,and the function of demand side resources in the formation of a healthy operation market is being re-recognized.After the electric power market reform,the United States put forward the concept of demand response(DR)regarding how to function well in the competitive market for the demand side.DR plays an important role in maintaining the system reliability and economic operation.Additionally,it guides the users to adjust their customary electricity consumption model through the market price or incentive mechanism,which not only improves the power consuming efficiency,optimizes the electricity consuming mode,but also alleviates the construction pressure of new power plant and electric circuit,improves the utilization of power grid assets.Access to demand side also has significant influence on the reliability of power system operation in addition to its economic benefits to the power market.As a crucial index to evaluate the system reliability,available transfer capability(ACT)can reflect the improvement degree of the implementation of DR by making quantitative analysis on the DR's influence on ATC system.Thus,in the bilateral open marketing environment,how to accurately grasp the influence of system loading change caused by DR on the calculation of ATC cannot be ignored.Under the circumstance of a bilateral open marketing environment of electricity generation and electricity selling,it is of great theoretical and practical significance to calculate the influence of DR on the research of ATC.In order to analyze the impact of DR on ATC in power system,a calculation method of ATC in the open electricity market is proposed.Taking the typical demand response resource-interrupt load(IL)as the research object,a bi-level optimization model considering the different interests of load serving entity(LSE)and independent system operator(ISO)is developed: the upper level of the proposed model chooses the users participating in the DR by minimizing the cost of LSE;the lower level determines the locational marginal price(LMP)and generation economic dispatch by minimizing the total generation bidding.The bi-level optimization problem is first converted to mathematical programming problems with equilibrium constraints(MPEC)by using the KKT conditions of the lower level of the proposed model.Then,the nonlinear terms of the constraints are eliminated according to the strong duality theory,thus the original model is transformed into a mixed-integer linear programming(MILP)model,which provides an effective way to solve other large-scale and complex optimization problems.Finally,using logistics optimization software GAMS,the simplified mathematical model is solved by CPLEXin GAMS.The active power distributed according to DR and generation bidding is taken as the ground state.Based on this,the ATC between areas is calculated.Taking into account the impact of DR,ATC value is more in line with the actual needs of the electricity market diversification,by adjusting the terminal load of electricity,to further achieve the optimal allocation of system resources.