Using System Disturbance Measurement Data to Develop Improved Load Models

Accurate load models are required to correctly understand the potential for voltage collapse and system oscillations following system disturbances. Transmission power flow limits are determined from studies of these conditions and the accuracy of the load models is critical. Electrical system steady state and dynamic response is currently available from a number of data sources, including power quality monitors, digital fault recorders (DFR), and phasor measurement units (PMU). This paper describes how these measurements can be used to develop models of the load behavior during and following disturbances. Applicability and usefulness of four possible load model structures are investigated. These four load model structures can be readily incorporated in a bulk system analysis tool. Parameter identification is the key for load modeling. A systematic approach that can be used for identifying and deriving appropriate parameters and composition percentages of the proposed load models directly from measurement data obtained during system disturbance is presented here. Example cases are provided to demonstrate the efficacy of the methodology