Inertia identification of power system based on energy function method

The ability of power system to suppress frequency change is closely related to its inertia level. Due to the advantages of low cost, clean and environmentally friendly, the penetration rate of wind power in the power system continues to increase. However, due to its strong randomness and poor controllability, its frequency is decoupled from the frequency of the power grid, and it cannot provide inertia support for the system when there is external active power disturbance, which will lead to the decline of the system inertia level and the power grid's ability to maintain frequency stability. In order to improve and evaluate the inertia of the system, it is necessary to study how to identify the inertia of the unit with the collected data. Based on the concept of generator port energy function, an inertial recognition method based on synchronous generator energy function is proposed in this paper, and the optimal inertia recognition window is determined by linear fitting method according to the frequency response of the outlet side after the disturbance occurs, which improves the accuracy of inertia identification. On this basis, the energy flow relationship of DFIG (Doubly-fed Induction Generator) is studied. Then, an inertial identification method based on energy function is presented, and its accuracy is verified in the simulation system.