Development of small signal model of a wind power plant: from source code to state space

Large-scale integration of wind power plants into the transmission system has altered the traditional generation mix. To perform an accurate stability assessment of the power network, transmission system operators (TSO) require a detailed small signal model that accurately represents the original equipment manufacturer’s (OEM) specific control system dynamics. This paper outlines the process of converting an OEM-specific converter code into state space matrix form. The methodology to accurately model control functionalities and non-linearities has been discussed. The resulting small signal model is implemented in the SSAT® tool. The accuracy of the small signal model has been validated with time-domain responses from a detailed PSCAD® model of a wind turbine. Furthermore, a small signal model of a wind power plant containing multiple wind turbines has been validated for plant-level studies.