Variable parameter practical model of synchronous generator for precise simulation of power system

The model of synchronous generator (SG) plays an important role in the simulation of power system and planning of power grid. With the constant parameter practical model (CPPM), it is difficult to consider the time-varying characteristic of the parameters affected by the complex non-linear factors, such as the saturation, distortion, skin effect and various spatial harmonics; thus, it cannot guarantee the precision of the simulation. In this paper, a variable parameter practical model (VPPM) of SG is proposed by coupling the CPPM with the three-dimensional parameter database and the parameter addressing model. The three-dimensional parameter database containing the steady-state, transient and sub-transient reactances and time constants is established with the terminal voltage, active power and reactive power as the variables. The parameters of the VPPM are selected through linear inter-polation according to the operating states of the generator. In order to verify the precision of the VPPM, a single-machine infinite system and a real power system with 204 buses and 107 generators are simulated. The result indicates that the VPPM is more accurate than the CPPM, and the stability limit and damping ratio calculated by the VPPM are larger than that by the CPPM. The study can provide important support for the precise simulation of the power system.