Operators of power grid supervisory control systems have to gather information from a wide variety of views to build situation awareness. Findings from a conducted field study show that this task is challenging and cognitively demanding. Visualization research for power grid supervisory control systems has focused on developing new visualization techniques for representing one aspect of the power system data. Little work has been done to demonstrate how information visualization techniques can support the operator in the sense making process to achieve situation awareness. To fill this gap, and with support from a field study, we propose solutions based on multiple and coordinated views, visual interactive filtering and parallel coordinates.