FUZZY LOGIC CONTROL FOR D. C. LINK

Abstract

This work presents a design of fuzzy logic controller (FLC) for HVDC link as affected by the operating conditions. The FLC design is based on the de current error and its change at the constant-current controller in rectifier station, and on extinction angle error and its change at the constant-voltage controller in inverter station, by regulating the firing delay angles of both stations.

The FLCs of the de converters are designed to control the de power passes in the de link under 50%, 100% and 150% full load operating conditions. The FLC is examined on a digital simulation program for three disturbance cases; change in de current order, load increase by 33% of its power and three-phase short circuit in ac line cleared by line outage.

The FLC design is tested also under the application of de power modulation technique in the rectifier controller. This technique is applied under two disturbance cases, load increase and short circuit, for the three operating points.

The simulation results depicted a superiority of FLC performance in reaching the steady state quantities at different dynamic disturbances as compared with the conventional PI controller. The results proved the visibility of designing the FLC controller for HVDC system that is good for a wide range of operating conditions without changing the structure or parameters of the controller.