Coordinated Control between Wind and Hydro Power Systems through HVDC Links

The main objective of this paper is to show how the control systems on wind farm turbines, HVDC cables and power generating units can be coordinated to improve power system balance in the event of a wind farm shut down due to a storm passing. The paper considers offshore wind farms located in West Denmark and HVDC cables connecting West Denmark with the Nordic system, where high shares of controllable balancing power are potentially available. The control systems investigated include turbine storm control, HVDC control and Load Following Control (LFC) in Denmark and Norway. The HVDC controller follows the ramp down of wind farm(s) production to compensate for the lost wind production, while the LFCs in Norway and West Denmark try to remove the area control error. Two cases were studied: A) Shut down of Horns Rev 2 (209 MW); B) Shut down of six planned offshore wind farms in West Denmark with combined capacity of 2000 MW. It is found that in both cases the coordination between the controllers either removes (Case A) or significantly reduces (Case B) the power imbalance, created in the Western Danish power system due to the shut down of the wind farm(s), by using hydro power generation in Norway, while keeping the frequency deviations in both power systems within acceptable levels. Such coordinated control will impact the current operation conditions in the region as well as require reservation of capacity on HVDCs and hydro power units. Copyright © 2012 Published by Elsevier Ltd.