Reduced-Order System Frequency Response Modeling for the Power Grid Integrated With the Type-II Doubly-Fed Variable Speed Pumped Storage Units

The traditional system frequency response (SFR) model is not applicable to the study of the frequency response of contemporary power grid due to the response of the large capacity (single unit up to 500 MW) type-II doubly-fed variable speed pumped storage (VSPS) unit is not considered. This article proposes an improved reduced-order SFR model for the power grid integrated with the large-scale type-II VSPS. proposed models Compared with the traditional SFR model, this model takes into account the active power coupling effect of this type of VSPS, and the computational burden increase of the model is small due to the model of VSPS has been reduced to the greatest extent. Therefore, the SFR model can be used by the system operators to rapidly calculate and evaluate the frequency response of contemporary power grid. Firstly, a reduced-order frequency response transfer function model of the Type-II VSPS is established by using the state-space model and small-signal incremental method. Compared with the higher-order nonlinear model of the Type-II VSPS, the state variables and computation burden of the established model is dramatically decreased. Secondly, an improved SFR model for the power grid integrated with the type-II VSPS is presented, and then the reduced-order analytical solution for the frequency response of the grid is put forward based on the parameter weighted aggregation method. The improved SFR model is more realistic and can better express the frequency response characteristics of the contemporary power grid. The proposed SFR model have demonstrated advantages in solving speed and efficiency when contrast it with the higher-order nonlinear model of the grid. Finally, the simulation and experimental results are respectively compared with the analytical solution of the reduced-order models, and the results have demonstrated the effectiveness of the.