Laboratory measurements and models of modern loads and their effect on voltage stability studies

Accurate load models are important in determining the status of a power system when subjected to sudden or gradual changes in operating conditions. This paper describes laboratory measurements and derived models of modern loads subjected to large voltage changes and their effect on voltage stability studies. Low-voltage, long-time models of loads such as modern air conditioners, discharge lighting and devices containing electronic-regulated power supplies were developed. One means used by utilities to avert voltage collapse has been system voltage reduction. The characteristics of modern loads and controls reduces the effectiveness of this voltage reduction. The results indicate the importance of using accurate load models, especially for large industrial loads where the load composition can be identified