Development of a dynamic ZIP-motor load model from on-line field measurements

We developed, using on-line field measurements, a dynamic ZIP-motor load model which attempts to capture the dynamic behavior of loads. The dynamic ZIP-motor load model consists of two parts: a static part and a dynamic part, where the static load is represented by a combination of constant impedance, constant current and constant power while the dynamic load is represented by an induction motor model. A procedure for building the model structure of the dyanmic ZIP-motor load model is developed. An effective solution algorithm for estimating the associated model parameters is presented. A notable feature of the algorithm is that the model parameters are estimated based upon pseudo-gradient information instead of exact gradient calculation. The proposed algorithm is easy to implement and can be used to identify nonlinearities associated with ZIP-motor models, such as models accounting for magnetizing and leakage reactances. The results developed in this paper are tested and evaluated using real field measurements from a real power system. It is shown numerically in the case study that the developed dynamic load model can accurately capture the dynamic behaviors of loads.