A Novel Method for Directly Calculating Dynamic Equivalent Generator Parameters

The dynamic equivalent of large power grid needs to calculate the dynamic aggregation of equivalent generator parameters for a given synchronous units group. In this paper, the weighted aggregation method commonly used in engineering is reviewed, and the deficiency of capacity weighting method is pointed out, then a direct parameters calculation method for dynamic equivalent generator based on EEAC and the unit-grid phasor diagram is proposed. Its key techniques are to using the complementary-cluster center-of-inertia relative motion transformation (CCCOI-RM) provided by the EEAC method, the initial value of the power angle for corresponding equivalent generator of the coherent generators group at the fault moment is calculated, and the impedance parameters of the equivalent generator are solved step by step by different forms of unit-grid phasor equations according to the feature that the power angle cannot be changed abruptly before and after the fault moment. Compared with the weighted aggregation calculation method, the proposed method is simpler and has a clearer physical concept. Simulation results based on the real power grids verify the effectiveness of the proposed method.