Research On Developing Algorithm For Analysis Of Power Transmission Limit Under Thermal Stability Constraints

With the interconnection of modern power systems and the development of power market in China, the transmission lines between the area of power generation and the load centers are frequently closed to the overload condition of thermal stability. At the same time, the problems of thermal stability are more serious because of the weakness of networks in China. The existence of long-distance and overload transmission lines is the cause of thermal stability breakage. Nowadays, more and more attention in system operation is paid to the computation of total transfer capability (TTC) for each concerned transmission interface. This paper studies and develops an effective TTC algorithm with the considerations of the practice of thermal stability assessment in China.Faced the thermal stability problems that happen frequently in Chinese network, this paper introduced two analogous methods of N-1 outage and proposed a practical method for thermal stability check using control card, which checks lines and transformers according to different areas and different voltage ranks.On the basis of check method, a novel computation strategy for TTC is introduced, which applies sensitivity analysis and adjustment method of equal and opposite quantities in pairs to calculation the adjustive sequence of generators. This strategy can decrease the dependence on experiences of dispatchers, improve the speed of computation and make power transmit limit more impersonal and exact.In addition, the check method and computation strategy can be applied in cooperation with the commercial software package for power system analysis used in China. This strategy can greatly relieve the burden in the computation of operation mode and improve work efficiency. Cases study on New England and the South China power system are given to show the validity and effectiveness of the method and strategy.