Research On The Fast Calculating Method Of The Steady-state Stability Power Limit Of The Transmission Section

With the growth of the power load and the scale of the interconnected power system, the structure of the power grid becomes more and more complex, the security and stability analysis of the power system operation has great significance. For safe operation of the power grid, it must meet the requirements of static stability firstly. Getting the steady-state stability power limit and the static stability reservation coefficient of the transmission section can be a very good investigation of the static stability level of power grid. The size of the steady-state stability of the transmission section is the one of the most effective evaluation indexes of the grid strength. It depends on not only the tie line itself, but also the transmission distance, the strength of sending system and end system, the impact point of the middle line, as well as the series and parallel compensation. In view of the significance of the static stability of power grid, fast estimate of the steady-state stability of the transmission section become the key problem to be solved for the operation personnel of the power grid. In this paper, we study the fast methods to obtain the steady-state stability of the transmission section and sludy proposed three different methods to quickly estimate the steady-state stability of the important section.1) The interconnected large system is equivalently transformed to a simple two-machine system through respectively calculating the short-circuit current of the sides system of the transmission section, and considers the influence of the equivalent voltage of the system to quickly estimate the steady-state stability of the section.2) Application of the principle of Thevenin’s multi-port equivalence, the power grid is equivalently transformed to a simple two-machine system though network topology analysis of the power grid and estimate the steady-state stability of the section.3) According to the value of the supplied short-circuit current of the tie-line of the section of each areas at short circuit moment, generators of the whole power grid will be divided for the coherent generator groups, then based on the real-time data provided by the WAMS, the power grid is equivalently transformed to a simple two-machine through the center of inertia. Fanally the steady-slate stability is calculated. Each of the three methods has different characteristics and application conditions, and the accurancy and reliability of these methods have been verified by the actual system cases. The prososed methods can provide a reference for the persons who are monitoring the characteristics of the power grid, these methods have a wide range of enginnering application.