Modelling and Aggregation of Loads in Flexible Power Networks

Load modelling seems to be a fully developed topic with tremendous research and effort having been applied to this subject. However, there is a renewed interest in industry and academia for this important topic which is particularly fuelled by the appearance of new, non-conventional types of loads (inverter-based or interfaced through power electronics) and requirements to operate modern electric power networks with increased penetration of distributed generation (wind, photovoltaic) in a safe and secure manner. The flexible operation of power networks of the future, both distribution and transmission, will depend even more on adequate modelling of all network components. Taking into consideration this background, a CIGRE working group C4.605 “Modelling and aggregation of loads in flexible power networks” was established in February 2010 with the aim of summarizing the current practices on load modelling and propose recommendations to utilities and power system operators for transmission and distribution system studies (steady-state, fault level calculation, transient and small signal stability; for operational and planning studies). Load models, and their parameters, currently used by utilities and system operators for power system analysis are generally not in public domain, and there is a level of uncertainty regarding industry acceptance of research efforts in this area. For this reason, a survey was conducted all over the world by members of WG C4.605 in order to identify current industry practice for power system load modelling through a comprehensive questionnaire on load modelling practices. This paper also gives the highlights of the final results of the survey.