计及可中断负荷的电力系统可用输电能力计算

为分析需求响应对系统可用输电能力的影响,提出一种开放电力市场环境下可用输电能力的计算方法。以可中断负荷这一典型的需求响应资源作为研究对象,构建考虑负荷服务实体和独立系统运营商不同利益需求的双层优化模型:上层模型以负荷服务实体的成本最小为目标,确定参与需求响应的用户;下层模型以发电总报价最小为目标确定节点边际电价,同时实现经济调度。将根据需求响应和发电机组报价分配的有功功率作为基态,在此基础上计算区域间可用输电能力。求解双层模型时,运用下层经济调度模型的KKT条件可将双层优化问题转化为均衡约束数学规划问题,根据强对偶理论消除约束中的非线性项,将原模型转化成混合整数线性规划模型。最后,在GAMS环境下调用CPLEX求解化简后的数学模型。通过对PJM-5节点、IEEE 30节点、IEEE118节点和IEEE 300节点系统的仿真计算,验证了所提方法的可行性和有效性,以及在可用输电能力计算中计及需求响应的必要性。

Available Transfer Capability Calculation of Power Systems Considering Interruptible Load

In order to analyze the impact of demand response(DR)to available transfer capability(ATC)in power system, a calculation method of ATC in the open electricity market is proposed. Taking the typical demand response resource the interruptible load 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 local marginal price(LMP)and generation economic dispatch by minimizing the total generation bidding. 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. 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. Finally, the simplified mathematical model is solved by CPLEX in GAMS. The feasibility and effectiveness of the proposed method are verified through the simulation of PJM-5-bus, IEEE 30-bus, IEEE 118-bus and IEEE 300-bus systems, as is the necessity of DR inclusion in the calculation of ATC.