Abstract: Direct electricity purchase by large consumers is the inevitable trend of electricity market reform in China, which will become the dominant form of the choice right of consumers. According to the characteristics of direct electricity purchase by large consumers, this paper proposes a new pricing method of transmission network wheeling cost for large consumers with considering the interruptible. Taking into account the electric quantity constraint and interrupt load constraint, this method establishes the interrupt congestion management model of large consumers. On this basis, the transmission long run incremental cost （T-LRIC） method is used for wheeling cost pricing. Finally, taking the IEEE 30-bus test system as example, this paper verifies the correctness of the proposed model, calculates and analyzes the influences of trading power and interrupt load on the congestion management and wheeling cost. The analysis results show that this method can effectively improve the economic efficiency of the transmission network and the congestion of transmission line, and delay its investment time, so the wheeling costs are lower than before, through the rational allocation of electricity contracts and the selection of interrupt load, which can provide guidance for power plants and large consumers reasonably purchasing power, and facilitate the development of our long-term deal of direct electricity purchase by large consumers in China.

Key words: direct electricity purchase by large consumers, wheeling cost, transmission long run incremental cost （T-LRIC）, congestion management, interruptible load