An induction motor parameter estimation method

The auxiliary systems of large thermal power plants are mainly driven by large induction motors. Their accurate modeling is essential for the analysis of black or emergency start procedures during power system restoration, where auxiliaries are started from relatively small diesel, hydro, or gas turbines, and where large voltage and frequency deviations occur. This paper proposes a new parameter estimation method for induction motors which allows to build induction motor models from manufacturer data such as nameplate data, and motor performance characteristics. The models can be used for black and emergency start studies with the Electromagnetic Transients Program (EMTP) or with stability programs. The method is based on a non-linear optimization routine. Its objective function, boundaries, and constraints are described in this paper. The method is first formulated neglecting saturation and then extended to allow for the saturation of the motor leakage reactances. It is tested to ensure that it is sufficiently robust and that its application gives the best agreement between model and manufacturer data. The effectiveness of the method is demonstrated for a 600-HP pump motor, such as typically used in large thermal power plants, and by a practical emergency start case study.