Comparative evaluation of neural network based and PI current controllers for HVDC transmission

An investigation into a neural-network (NN) -based controller, comprising an NN trained offline in parallel with an NN trained online, is described. This NN controller has the potential of replacing the proportional-plus-integral (PI) controller traditionally used for HVDC (high-voltage direct-current) transmission systems. A simplified theoretical basis for the operational behavior of the individual NN controllers is presented. Comparisons between the responses obtained with the NN and PI controllers for the rectifier of an HDVC transmission system are made under typical system perturbation and faults. It is shown that the combined NN controller can adapt its weights online to provide improved or similar performance, when compared to traditional PI controllers, for small- and large-signal disturbances. The response of this simple NN controller is somewhat slower for very fast transients, perhaps due to the inadequate training