Commutation failure reduction in HVDC systems using adaptive fuzzy logic controller

The use of fuzzy logic controllers to improve the performance of HVDC systems under various faults and operating point changes has been well-documented. Recent research has shown that the optimal membership function width in a fuzzy controller is different for different system events (such as current order change or fault). This paper proposes an adaptive approach to designing a fuzzy logic controller for HVDC systems. Simulation data are used to create a look-up table for the fuzzy control system. Based on the operating point and the type and location of fault, the output of the table indicates the membership function width to be used in the fuzzy controller to obtain the best results (i.e., the lowest number of commutation failures). This paper presents the best controllers for nine faults at 27 operating points for the CIGRE benchmark HVDC system, but more importantly, uses trends to develop a method for finding these optimal controllers for other systems without the need for exhaustive simulation of each possibility. Index Terms--Adaptive control, fuzzy logic, HVDC transmission control.