Optimization of Rwanda power system protection in power blackouts and cascading events

Abstract

Rwanda’s power system security is the most important in optimization of grid frequency to prevent power blackouts caused by load disturbances and power imbalances. To manually stabilize and restore network frequency, a tuned PID (Proportional, Integral, and Derivative) controller was used, but it was inefficient and unreliable. The objective of this article is to develop a system that can be used to balance generation—demand powers during power outages by alle- viating grid frequency in load disturbance cascaded events. By balancing power generation and demand, the balanced steady-state approach was proposed and developed to restore and optimize grid frequency to its normal state. This technique used PID-Power System Automatic Stabilization (PID-PSAS) technique based on load frequency control. The load disturbances of ± 20%, ± 10%, and ± 5% of a 250 MW power load were considered. MATLAB/Simulink was utilized to model and simulate the Rwanda power and controller systems. The results showed that the frequency responses of single and two area western and northern grids were reduced to 13 ∗ 10−5 Hz, 15 ∗ 10−6 Hz, and 0.251 s for overshoot, steady-state error, and settling time respectively. The proposed control system performance of 99.86% success rate was achieved and compared with the current control techniques of 70.6% performance rate. A stable frequency was observed at any disturbances and more than 300 megawatt losses were mitigated. Finally, the developed control technique rapidly stabilize the frequency and balance the generation-demand powers after 0.251 s. Future works have to focus on 0 Hz of steady state errors using cyber-physical power optimization systems.