Load Sensitivity Studies in Power Systems With Non-Smooth Load Behavior

One of the most important aspects of time-domain simulations for power system planning studies is load modeling. For a realistic representation of the load, the Western Electricity Coordinating Council (WECC) model validation and working group developed the composite load model. The composite load model represents the aggregation of different types of loads at the substation level. However, there exists some uncertainty in determining the load parameters and the percentage composition of the different components. Trajectory sensitivity (TS) analysis provides a systematic approach to study the impact of parameter uncertainty on power system response to disturbances. The non-smooth nature of the composite load model may present some additional challenges to sensitivity analysis in a realistic power system. This paper presents an application of TS analysis to study the impact of load parameter uncertainty on the system response. The impact of the non-smooth nature of load models on the sensitivity analysis is also addressed. This paper further suggests a method to determine the perturbation size limit for which accurate linear approximations can be made. The study was performed using the WECC system model.