Inertia Estimation Method Of Interconnected Power Grid Based On Electromechanical Oscillation Characteristic Parameters

With the advancement of science and technology and the development of the times,the State Grid presents the overall trend of interconnection of large areas,and the resource is fully optimized.New energy sources such as solar energy and wind energy are continuously added to the power grid,and the energy structure of the power system is undergoing huge changes.This makes the equivalent inertia of the system significantly lower and poses a serious threat to the control of the system frequency.Therefore,how to accurately estimate the inertia of the system in real time becomes extremely important.Aiming at the inertia of the interconnected system,this paper proposes a method for estimating the inertia of the interconnected system in real time based on the characteristic parameters of the electrical oscillation of the small disturbance engine.The specific contents are as follows:In this paper,the equivalent model of the interconnected power system is first established,and the complex interconnected system is equivalent to a two-region system,which is further equivalent to a single-machine infinity system,and the consistency of the equivalent parameters and the actual system parameters is verified.Then based on the single-machine infinite system model,the rotor motion equation is used to establish the relationship between the system inertia and the electromechanical oscillation characteristic parameters,and the interval oscillation mode characteristic parameters are used to estimate the equivalent system model inertia.For the extraction of oscillation parameters,this paper uses the random subspace method for identification.Taking the IEEE four-machine two-region system and the IEEE16 machine 68-node system as examples,the time series data of generator angular velocity is used as a reference to verify the identification algorithm.The comparison of the identified oscillation parameters and modal graphs with the actual values shows that the random subspace method is effective and accurate in identifying electromechanical oscillation characteristic parameters.According to the proposed method of interconnected power grid inertia estimation based on electromechanical oscillation characteristic parameters proposed in this paper,for the four-machine two-region system,the system inertia is adjusted by adjusting the system inertia,and the system is re-estimated,and compared with the standard inertia in their respective operating modes The inertia estimation method has the ability to track the system inertia changes in real time,and has high accuracy.For the 16-machine 68-node system,the equivalent inertia of the system under 9 different power flows is still highly accurate,which verifies the practicability and feasibility of the algorithm in the actual operating system.The system equivalent inertia estimation method proposed in this paper plays an important role in frequency control of new energy grid-connected actual systems.Real-time estimated system inertia allows the control center to detect system characteristics in a timely manner and make corresponding adjustments to reduce The low inertia caused by structural changes threatens the system.