全国统一电力市场演进过程下省间-省内市场出清及定价模型

Inter-and Intra-Provincial Electricity Market Clearing and Pricing Model under the Evolution of National Unified Electricity Market

为了促进电力资源在省间的余缺互济和在全国范围内的优化配置,我国正有序推进电力市场改革,逐步实现省间-省内市场的耦合和全国统一市场的演进。根据省间-省内市场耦合程度的不同,该文将演进过程划分为三个阶段:分层阶段、松耦合阶段和紧耦合阶段。进一步考虑跨区、跨省以及省内输电的输电费回收问题,跨区直流输电线路与区域内交流输电线路按照传输电量收费,省内线路按照用户负荷用电量收费。构建了面向不同输电费收取方式的出清模型与定价机制,分层阶段采用顺序出清,松耦合阶段采用双层迭代出清,紧耦合阶段采用统一出清,定价机制均采用节点电价定价机制。最后,利用IEEE 39节点和118节点系统进行仿真计算,验证了出清模型和定价机制的有效性,并分析了输电费对出清和定价结果的影响。

At present,China's inter-and intra-provincial market system is still in its infancy,and market mechanisms,operation methods and clearing models are yet to be explored.The commonly used modeling approaches in the existing literature include path-based and sensitivity-based optimal clearing approaches.The path-based approach increases the dimensionality of decision variables in the high-low matching discounting process,resulting in a large model size.And,the sensitivity-based approach adopts an integrated clearing method but does not provide an applicable pricing mechanism.To address these issues,this paper constructs a sensitivitybased inter-and intra-provincial electricity market clearing model that considers different ways of collecting transmission fees.Furthermore,the nonlinearity introduced by the transmission fees is linearized and the locational marginal price(LMP)method is used to solve the problem of unclear pricing of the sensitivity-based model.China's transmission lines include inter-regional transmission lines,intra-regional inter-provincial transmission lines and intra-provincial transmission lines.Their transmission pricing mechanisms are introduced and their impact on the supply and demand balance in the electricity market are analyzed.As the evolution of the national unified electricity market,the inter-and intra-provincial electricity market will go through three stages of bi-level stage,loosely-coupled stage and tightly-coupled stage.The degree of coupling between inter-provincial and intra-provincial markets varies at different stages,with the lowest degree of coupling at the bi-level stage and the highest degree of coupling at the tightly-coupled stage.The clearing model and the pricing model were constructed for the three stages.And the proposed pricing mechanism derives the price for each node adopting the LMP method,which has good characteristics such as incentive compatibility and non-discrimination.To verify the effectiveness of the proposed clearing model and pricing model,simulations were conducted in the IEEE 39-bus and 118-bus systems.The clearing results show that the social welfare in the bi-level stage,loosely-coupled stage,and tightly-coupled stage is 27028061¥,30543641¥,and 31874432¥,respectively.Also,the transmission power of cross-regional tie-lines is the highest in the tightly-coupled stage indicating high utilization of the cross-regional tie-lines.Besides,the pricing results show that the imbalance funds in the bi-level stage,loosely-coupled stage,and tightly-coupled stage are 2801963¥,2051259¥,and 0¥,respectively.And,the price at each node is different due to the transmission fees of intra-regional inter-provincial AC tie-lines.Further,the impact of transmission fees on clearing results and pricing results was analyzed.As the transmission price of inter-regional transmission lines increases,both the transmission volume and social welfare decrease,and the average price in the receiving provinces increases while the average price in the sending provinces decreases.As the transmission price of intra-regional inter-provincial transmission lines increases,the difference in electricity prices between the nodes becomes more pronounced.Assuming that the intra-provincial transmission price in both the sending and receiving provinces decreases by 10¥/(MW·h),the bids for generators and loads in the sending provinces increase by 456 MW·h and 481 MW·h,respectively,while the bids for generators and loads in the receiving provinces increase by 3804 MW·h and 3781 MW·h,respectively.The following conclusions can be drawn from the simulation analysis:(1)Inter-provincial transmission can increase social welfare and promote optimal resource allocation.And the tightly-coupled stage clearing is best able to maximise social welfare.(2)The proposed pricing mechanism remains applicable when considering multiple transmission fees and has the advantages of LMP.And the pricing mechanism provides a reasonable pricing methodology for sensitivity-based clearing models.(3)Transmission fees charged according to the actual power flow of transmission lines result in a differential price at each node.The sensitivity of the node to the line in the same direction as the power flow will result in a lower price for the node,and vice versa.