Aggregation of Wind Turbine Grid-Side Inverters by Voltage Angle and Cable Resonance Compensation

The aggregation of wind power plant (WPP) radial is a useful way to speed up the simulation and simplify the analysis of large-scale WPP. The traditional aggregation method for radial is to make the voltage drop or power loss across inter-turbine cables be equal between aggregated model and unaggregated model. However, the accuracy in high frequency range is not guaranteed in these two aggregated models. And the difference between the output voltage angle of each wind turbine (WT) in a radial is not taken into accounts, so the mismatch might be observed in each channel of aggregated model and unaggregated model with asymmetrical WT control. To deal with this issue, this paper presents an aggregated model for WTs with the ability to compensate inaccuracy in high frequency range and the difference in each channel by adding the compensation inductor to the aggregated WT. The analysis shows that the effective output admittance of the aggregated model matches well with the unaggregated model, thus the small-signal dynamics of WPP are not change after aggregation. The frequency scan and step response test performed in PSCAD/EMTDC simulation verify the accuracy of aggregated model.