Robert Zavadil

Making connections [wind generation facilities]

Large-scale wind generation facilities have become a very visible component of the interconnected power grid in many options of the United States. Only a decade ago, wind generation facilities were viewed by most power engineers as a novelty, and by simple engineering judgement, it could be safely concluded that the effects of these unique but smaller facilities on system reliability would be negligible. Now, with individual wind generation facilities approaching the output rating of conventional power plants, a deeper understanding of their potential impacts on the interaction with the bulk electric power system is needed.

A mighty wind

Developments in the world of wind continue to happen at record speed. The world as a whole is in the midst of grappling with an epochal transition from a system dominated by fossil and nuclear fuel to one that relies much more heavily on renewable energy. No technology breakthroughs are required for the United States to achieve the scenario of 20% of electricity from wind by 2030. Instead, many evolutionary steps executed with technical skill, which can cumulatively result in a 30-40% improvement in the cost effectiveness of wind technology over the next few decades, are expected to occur.

Models for Change

Not much more than a decade ago, the desired action for a wind generation facility was to shut down or disconnect electrically in the event of a disruption on the bulk electric system. This, of course, was a reflection of the novelty that was wind generation at the time, as well as prudent engineering judgment, as the loss of a small amount of generation-the wind plants that were in service at the time-posed little risk to system reliability.

A whirl of activity

IEEE activities related to wind power and other alternate energy technologies were under the purview of the Energy Development Subcommittee (EDS) of the Energy Development and Power Generation Committee (EDPG) from the 1970s to the early 1990s. Wind power spans the areas of interest of many technical committees within the Power & Energy Society (PES). Given the exponential growth in wind power during the past decade, PES established the Wind Power Coordinating Committee to provide focus. PES has responded with more working groups, task forces, panel sessions and tutorial related to wind power. This trend is expected to continue for the foreseeable future, with new PES activities in additional technical areas related to wind power (e.g., transformers, power system relaying, surge protection, operations, and market structure). Now, it is up to the power system engineers to understand the technical challenges and develop workable methods for integrating increasing levels of wind generation in power grids.

The role of wind forecasting in utility system operation

The rapid growth of wind generation is introducing additional variability and uncertainty into power system operations and planning. While wind power forecasts are increasingly important, forecasts are not sufficient: we must also identify how forecasts are to be used and the tools necessary to support operators and planners. We present a broad view of these challenges and focus on some of the more immediate opportunities to use forecasts. In particular, we focus on opportunities to use visualization, warning systems, and automation to support control-room operations.

Flicker from distributed wind generation

From 2003 through 2008, the Utility Wind Integration Group (UWIG) monitored the performance of one 950 kW turbine located in Palmdale, CA, one 50 kW turbine located in Calverton, NY, and four 50 kW turbines located in Selawik, AK under actual operating conditions. Complete data are available through the UWIG website, with views of real-time and historical data and events. In this paper, we (1) inform about general flicker concerns associated with connecting large numbers of Type 1 or Type 2 turbines to a distribution system, (2) use the UWIG data to statistically characterize flicker during continuous operation and switching operation of wind turbines, (3) use the statistical information of one of the monitored wind turbine types to calculate turbine-specific flicker coefficients that can be used to predict the flicker impact of this turbine type during the planning stage of distributed generation projects, and (4) investigate the correlation of flicker and other electrical parameters.