Abstract: The transaction model constitution and the transmission congestion management in the process of power transactions constitute a key issue in the normal operation of the power market．In this paper‚by drawing on some o-verseas experiences an according to the specific conditions of Chinaʾs reform of the power market at its earlier stage‚a new transaction model and transmission congestion management method was proposed based on the investigation into the power market in Guangdong Province．In the congestion management‚the corresponding least reduction of social benefit is taken into account and the cost of the congestion management is distributed in accordance with the load con-gestion dispatching factor．A numerical example was finally presented to prove the validity of the proposed method‚which is of practical significance to the development of the power market‚especially to the construction of electric net -works．

Key words:  district cooling system, pipeline, optimized design, variable cooling load