Adaptive Setting of UFLS Relay Using Hourly Programming with Consideration of Renewable Energy Sources in Smart Grid

In the light of the emergence of smart grids, the functions associated with this type of grids in the blocks of the energy management system require the adoption of robust strategies in order to provide a higher level of control and protection. Under-frequency load shedding (UFLS) sheds load blocks when the frequency drop is below the threshold limit. In adaptive UFLS, in an advanced telecommunications platform, the main quantities of the system are measured at each hour and in real-time; besides, the optimal amount of load is shed according to frequency deviation. In this paper, an hourly framework using Mixed-Integer Linear Programming (MILP) is proposed for an optimal design of an adaptive UFLS in smart networks. The goal is to provide a more systematic adaptive UFLS that is less dependent on trial and error. Here, the under-frequency relay is set for each hour in regard to operating conditions and uncertainties resulting from contingencies, to renewable energy sourses (RES), and to load fluctuations at that hour. The simulations are performed on the IEEE 39-bus test system over a 24-hour time horizon.