Adaptive Reduced-Order Method of Aggregated Impedance Model for Large-Scale Photovoltaic Stations Small Signal Stability Analysis

Reduced-order method for aggregated impedance modeling is an effective way to simplify the small-signal stability analysis of the large-scale photovoltaic stations with hundreds of PV generators. However, it is difficult for the existing reduced-order method to achieve the best compromise between the better small-signal oscillation mode preservation and the minimum target reduction order of the impedance aggregated model. To address the problem, this paper proposes an adaptive reduced-order method for aggregated impedance model reduction, in which, the frequency-interval balanced model reduction theory is used to truncate the redundant part of the aggregated impedance model for each rolling step of the impedance aggregation. A frequency-domain error index is established to evaluate the error of the reduced-order aggregated impedance model so that the expected reduction order can be obtained adaptively. The impedance model of the large-scale photovoltaic station with 17 inverters operating under different parameters is set up in MATLAB to verify the proposed method. Simulation results show that the reduced-order aggregated impedance model obtained by the proposed method can be effectively adapted to the small-signal stability analysis of the large-scale photovoltaic stations.