Improving Stability Through Adaptive Under-Frequency Load Shedding: the Zambian Scenario

Under-frequency load shedding (UFLS) is one of the interventions employed for power system frequency stabilization and has the potential to increase grid flexibility. Such flexibility is necessary to accommodate the integration of variable renewable energy sources (VRES) such as Solar. This paper presents a summary of a study that was undertaken to evaluate the frequency response of the Zambian integrated power system for different under-frequency load shedding (UFLS) scenarios and contingencies using the steep gradient strategy. With the power system simulation for engineering (PSS/E) tool, the islanded and interconnected scenarios of the system were simulated. The study showed that, while 10% UFLS gave the best response in all scenarios, the system frequency recovered at a better nadir and had no overshoot in the modified-interconnected compared to the islanded and interconnected scenarios.