Dynamic Equivalence Modeling of Wind-thermal-bundled Power Transmission Through VSC-HVDC System Based on Trajectory Piecewise Linearization

The wind-thermal-bundled power transmission through DC is a high-order nonlinear system, which has the disturbance caused by the variable operation mode and the uncertainty of wind power generation. Establishing a full-order model to describe the motion process after the disturbance is necessary. However, the simulation speed of the full-order model is slow, and it is not easy to design the controller. Therefore, a global linearization modeling method is proposed in this paper. Firstly, the full-order electromagnetic transient model of DFIG and VSC-HVDC is established in the DQ reference frame, and SRF-PLL connects the whole system. Then, three operating modes and two typical perturbations of the system are set, and Matlab/Simulink obtains the trajectory of disturbed motion. Furthermore, the Trajectory Piecewise Linearization (TPWL) method is used to establish a dynamic equivalence model of the wind-thermal-bundled power transmission via DC, including critical operating point selection, linearization, reduction, weight calculation, and Simulink verifies it. The results show that the dynamic equivalence model is highly consistent with the electromagnetic transient model after perturbation under the appropriate sampling point rate, which verifies the correctness of the global linearization modeling method.