Modelling and Simulation: A Comparison of LQR Control and Unified Power Flow Controller for Dynamic Stability Improvement

Improved dynamic stability of the Single Machine Infinite Bus
(SMIB) system can be done with UPFC control and LQR
Control. This study examines the use of optimal control and
Unified Power Flow Controller (UPFC) devices to improve the
stability of the SMIB system. The SMIB system is a single
generator connected to an infinite-bus. The SMIB system
model is made in the form of a state-space variable equation,
then compiles the Riccati matrix equation to determine the gain
optimal in the Linear Quadratic Regulator (LQR) control
system. The input of the optimal gain amplifier is obtained from
the angle of swing (Δδ) and the rotor speed (Δω), as well as the
internal voltage (Vt) and the voltage change at the anchor. The
output of the LQR control is injected on the excitation system
of the SMIB model. The LQR control system is compared to
the UPFC control system. The UPFC device is installed on the
transmission line. UPFC was formed in a new mathematical
equation model of injection. The UPFC injection model
controls the Pi and Pj power parameters (Power injected on
bus-i and bus-j). Installation of the UPFC device is used to test
the repair of oscillation of the electric power system.
Comparison between systems in an open loop and closed loop
state (using LQR and UPFC controls) is made using Simulink.
The performance of the open-loop and closed loop systems,
namely the observation of oscillation changes in the rotor angle
is used in determining the level of repair of system oscillation
attenuation. From the tests conducted, it can be seen that the
use of UPFC is better than the LQR control in reducing overshoot and reducing oscillation changes in the rotor angle to
reach the steady state.