Generic dynamic load models in long-term voltage stability studies

The aim of this paper is to examine up to what extent the so-called generic non-linear dynamic (GNLD) load models can replace a more detailed represen tation of aggregate load, including induction motors, thermostatically cont rolled and static loads, in long-term voltage stability simulations. In the first part of the paper the main characteristics of the GNLD models are co mpared with those of more detailed models considered as 'reference'. It is concluded that the long-term instability phenomena are closely reproduced, in most cases, by using the GNLD model. The accuracy of the GNLD reproducti on depends on the load characteristics, the type of phenomena that have to be reproduced and the position of the load in the network. Short-term insta bility phenomena solely due to induction motor dynamics might not be reprod uced with adequate accuracy by GNLD models that are characterised by an inh erent de-coupling of active and reactive power. Further, the possibility of including on load tap changer transformer into GNLD models is investigated and accomplished. These considerations are illustrated by adopting as case study a network often used in the literature. (C) 2000 Published by Elsevi er Science Ltd. All rights reserved.