Development of Dynamic Equivalent Models for Large Scale Wind Power Plants

Thesis (Ph.D.)--University of Washington, 2014An individual wind turbine has trivial influence on existing power systems owing to its very small percentage of the total generation. In contrast, wind power plants (WPPs) that have large numbers of wind turbines in relatively small areas have significant impacts on the power systems, and thus their influence must be considered in the studies. This dissertation is of developing suitable dynamic models of WPPs for power system dynamics study. In this dissertation, dynamic equivalent models (DEMs) for large scale WPPs are proposed for the dynamics study. As the dynamics of a WPP are the resultant dynamics of interconnected multiple wind turbines, its DEM is developed based on the knowledge of individual wind turbines and their interactions. In addition, as the dynamics of individual wind turbines are related to their control scheme, this study explains how to achieve an optimized control scheme for them with the use of the DEM. For a certain purpose in which a WPP is considered as an external system for dynamics study of a power system, its DEM can be developed based on measurements at point of interconnection without any pre-knowledge of the WPP. For the case, this dissertation also proposes a DEM developed using an adaptive system identification method. In addition, this study explains how to model an adequate power system for simulation tests. The validities of the proposed DEMs developed in this dissertation are verified by the simulation results with the power system model