Dynamic Load Models for Industrial Facilities

Industrial facilities connected to power transmission systems typically draw large amount of power and have complex dynamic responses to system disturbances. Traditional load modeling approaches cannot establish adequate dynamic models especially for future industrial facilities in power systems planning studies.;Variable frequency drives (VFDs) are increasingly used in industrial facilities, however, dynamic models for motor drive systems suitable for power systems dynamic studies are not available. Voltage sags occur when power systems experience short-circuit faults, which is typically the starting point of power systems dynamic simulation. VFDs will trip when they experience a relatively large voltage sag (>20% - 30% voltage drop). As a result, there is no need to include VFDs in dynamic studies. Based on the finding, a simple procedure to determine if a VFD needs to be included for dynamic studies is proposed in this thesis.;When VFDs experience mild voltage disturbances and are able to ride through, the equivalent dynamic model for motor drive systems is proposed. These models are created by the linearization approach, voltage dependence and frequency dependence are both considered. Dynamic models for VSI and cascaded inverter drives and their induction motor loads are developed. Aggregation algorithms for motor drive systems are proposed to achieve load equivalence facility wide.;A generic dynamic load model structure covering all types of commonly used loads including motor drive systems is proposed for industrial facilities. A procedure is provided on how to obtain the final load model, which is tailored from the generic structure based on load types practically involved in an industrial facility of interest.;In this thesis, a new concept, the template-based load modeling technique along with template scaling and model equivalence algorithms, is proposed to address this issue. This method requires minimal user input and can be implemented in a database program for a wide variety of industrial facilities. Oil refinery facilities are used as an example to illustrate the proposed technique.