DEVELOPMENT OF A FREQUENCY-DEPENDENT COMPOSITE LOAD MODEL USING THE MEASUREMENT APPROACH

In control and stability studies, load models should realistically rep resent the aggregate load behavior of all kinds of individual componen ts. In this paper, the development of a composite load model, where th e load is represented as a combination of an RC circuit in parallel wi th an induction motor equivalent circuit, is presented. A procedure is developed for identifying a frequency-dependent composite load model using digital measurements from an on-line transient recording system, taking account of system frequency variation. A nonlinear model param eter estimation technique is described to derive the frequency-depende nt load model. A computer program called LMSP has been developed. The program consists of five major phases: user-interface, data manipulati on, load model identification, model conversion and system model respo nse evaluation. A case study is presented to illustrate, in particular , the accuracy of the developed model for the representation of dynami c load behaviors of an actual power system.