A new report finds that with high penetrations of wind and solar on the grid, together with good system planning, sound engineering practices, and commercially available technologies, the Western Interconnection can withstand the crucial first minute after large grid disturbances. Acceptable dynamic performance of the grid in the fractions of a second to 1 minute following a large disturbance (e.g., loss of a large power plant or a major transmission line) is critical to system reliability.

The report, published by the U.S. Department of Energy’s National Renewable Energy Laboratory and General Electric Energy Consulting, is titled The Western Wind and Solar Integration Study Phase 3–Frequency Response and Transient Stability. The report covers the third phase of the Western Wind and Solar Integration Study (WWSIS). WWSIS explores whether large amounts of wind and solar energy can be integrated into the western electric power system, and is one of the largest regional solar and wind integration studies to date.

The first phase of the WWSIS examined the operational impact of up to 35% penetration of wind, photovoltaic, and concentrating solar power energy on the electric power system. The goal was to understand the effects of the variability and uncertainty of wind and solar and investigate mitigation options. The study found that these levels of wind and solar could be integrated if certain operational changes could be made, such as intra-hour scheduling and balancing area coordination.

Phase two of the study examined the impacts of fossil-fueled cycling on emissions and wear-and-tear costs. It found that cycling did not significantly reduce the emissions benefits or avoid fuel savings that come from wind and solar.

Phase three of the study focused on reliability and stability. Large-scale transient stability and frequency response are critical to grid reliability, particularly for the Western Interconnection, which has a long history of dynamic performance constraints on its operation. The new report specifically addresses the performance of the Western Interconnection with high penetrations of renewable energy.