Gain scheduling adaptive control strategies for HVDC systems using fuzzy logic

The paper introduces different types of fuzzy tuning methods for the controller parameters of the firing and extinction angle controller of an HVDC link. The test system, a point to point DC link has been subjected to various small and large disturbances to examine the effectiveness of the proposed schemes. The current error and its derivative in the case of a rectifier and the gamma error and its derivative in the case of the inverter are taken as the two principal signals to generate the change in the proportional and the integral gains according to a definite rule base. The results obtained have been compared graphically to prove the superiority of the proposed controllers.