Dynamic equivalent model for system frequency response considering multiple induction motors
As more and more renewable energy resources are connected to the grid through power converters,the inertia of the power system is decreasing.At the same time,a large number of induction motors on the load side can provide frequency support and improve frequency response dynamics.However,accurate modeling of such a large number of induction motors requires detailed parameters and heavy computational cost.To address the limita-tion,a data-driven model for system frequency response is proposed.By collecting historical data of system fre-quency response,the identification of the equivalent inertia and damping coefficient of the power grid is described as an optimization problem.The objective is to minimize the frequency difference between the model and historical data.A heuristic algorithm is adopted to solve the problem efficiently.Compared with the mechanism model,the proposed dynamic equivalent model is structurally simple and does not require detailed parameters of induction mo-tors.Simulations on a modified IEEE 9 bus system verify the effectiveness of the proposed method.The results also show that the induction motor load,which has a self-inertia of 1.5 seconds and accounts for 22%of the load side,provides 9%equivalent inertia to the system.
system frequency responseinertia estimationinduction motorsheuristic algorithm
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