Study on Small Signal Stability of Power System Under MGP Grid-connected Structure

After the new energy is connected to the power grid through the inverter, it will reduce the inertia constant and damping coefficient of the power grid, which will lead to the prominent problem of small signal stability. To solve this problem, this paper proposes a new energy grid-connected method based on the synchronous motor-generator pair(MGP)system, which can improve the inertia of the power system and contribute to the small signal stability. Firstly, this paper introduces the grid-connected structure of new energy based on MGP, and then establishes the small disturbance stability model of MGP, the small disturbance model of doubly-fed turbine based on MGP, and the small disturbance model of direct-drive turbine and photovoltaic based on MGP. And then, the damping ratio of MGP is studied. Finally, based on the single machine-infinite bus system, we can draw a conclusion that MGP can give more damping than traditional units under the same working conditions. And the inertia level is close to that of traditional units.