The role of demand response in power systems with low inertia

Variable renewable energy sources (RES), wind and solar, are increasingly being used worldwide in the production of electricity. Its dissemination can substantially contribute to reducing the ecological footprint and minimizing external dependence of energy importing countries. However, their increasing penetration into power systems has raised a number of issues, linked to the characteristics of both the primary energy sources (variability and dispatch ability) and of the generators (less inertia available compared to conventional synchronous generators). It is well known that inertial response capability of power systems is a critical characteristic for its adequate behaviour when imbalances between generation and consumption occur. This work aimed to evaluate the impact of the dissemination of RES with low inertia (wind and solar) on the system response to events that tend to provoke imbalances between generation and demand. Namely, comparing the behaviour of power system when different renewable generation technologies are used, or the role of more advanced renewable generation units - second generation - (mainly the control system). Also the role of demand management, more specifically load curtailment events, on the behaviour of the system in face of imbalances is investigated in detail. The IEEE 39 bus power system was used in this study and the simulator PowerWorld has been used. It was possible to state that despite the lower inertia in systems with high penetration of variable renewable it is possible to have adequate responses due to the characteristics of the new generation and / or control technologies. Also, it is possible to conclude that the use of demand management to improve the response of the power system, depends a lot on the predominant generation technology and the instant of time in which those management actions are implemented.