Damping Inter-area Modes of Oscillation and Improving Transmission Capacity Using Global PSS

With the development of power grid interconnection, the low frequency oscillation is becoming more and more prominent which threats the stability of the system. It consists of local modes and inter-area modes, and the effectiveness of local PSS in damping inter-area modes is limited. Then the global power system stabilizer (GPSS) based on WAMS (Wide Area Measurement System) is proposed. First 3 problems about the global damping control (the design of GPSS, the choice of GPSS location and input signals) are described. Then global PSS providing a supplementary signal to the excitation system to improve power system stability limit and transmission capacity is presented. At last a simulation on a two-area, four-machine system is tested to prove the effectiveness of global PSS utilized in the two aspects.