Non-linear load modeling - Requirements and preparation for measurement

The existing software for the simulation of power system operation uses mostly simple load models such as the constant power load model, the constant impedance load model or the static polynomial load model to represent the real system load characteristic. In some cases using such load models in power system dynamic simulation may produce inaccurate results and lead to inappropriate system operation. In this paper load modeling using field measurement data from a load bus in the power grid to improve the simulation accuracy in the study of power system stability is discussed. The goal is to investigate the influence of different perturbations in the power grid on load behaviors as preparation for field measurement. Furthermore, there is a focus on the definition of measurement requirements. In addition, the nonlinear least-squares algorithm used to identify load model is discussed. As preparation, a complex nonlinear load model with predetermined parameters will be simulated in some defined scenarios, the simulation results are compared with a constant power load model. By using the transformer tap changer to make perturbations in the power system, the load dynamic characteristics could be gathered, and the perturbations data could be used to identify the parameters of the non-linear load model.