Focusing on low inertia and damping problems brought about by high penetration of renewable energy

this paper proposes the motor-generator pair(MGP)system of renewable energy resource for wind power integration and a detailed modeling method for small-signal stability. First

according to the rotor angle relation of MGP and dynamic process of excitation systems

state equations are established considering the automatic voltage regulator(AVR)and power system stabilizer(PSS)

while pointing out that MGP has superimposed effect for damping torque. Then

a comprehensive model consisting of all state variables of doubly-fed induction generator(DFIG)and MGP is developed. On this basis

representation of the torque component based on K coefficients is derived to reveal that the coupling characteristic of dual excitation is the essence of superimposed effect. Finally

a single machine infinite bus system is tested based on established models. Characteristics of small-signal stability of MGP and traditional generation unit are compared. The oscillation modes dominated by wind turbine are also analyzed with dual excitation coupling taken into account when the wind farm is connected to the grid the traditional way using MGP. Results show that the proposed modeling method can accurately reflect the dual excitation characteristic of MGP to effectively enhance the output component of damping torque and improve oscillation modes.