Optimization Model and Calculation Method for Thermal Stability Limit of Transmission Sections

In China, the monitoring regarding power grid dispatch usually adopts section monitoring rather than real-time static safety analysis. The manual calculation process is so complicated that it is necessary to calculate the thermal stability limit of the transmission section through optimization. In this paper, the active power flow of the section after the expected disconnection is expressed as a linear function of the initial active power flow of the section, with the aid of the concept of transfer ratio. The constraints on the initial active power flow of the sections are determined according to the current carrying capacity. The maximization of the minimum ratio between the sectional thermal stability limit and the initial active power flow is taken as the basic principle. The optimization model of the sectional thermal stability limit is proposed and is solved with simplex algorithm from linear programming. The correctness of the model and the effectiveness of the calculation method are verified with the case study of an actual provincial power grid.