UNDERFREQUENCY CONTROL OF THE NELSON RIVER GENERATING STATION BY MODULATING POWER FLOW ON THE HVDC LINK.

The development and implementation of a control system that modulates the power of the HVDC link to control the frequency of the Nelson River generating system of Manitoba Hydro is described. Results from simulation studies and field tests are presented. It is shown that the frequency based power balance controller - which incorporates direct coupled, proportional and integral controllers, as well as a derivative controller - performs as predicted in preventing underfrequency collapse of the generating system.