Integrating renewables into the grid while maintaining or improving reliability
We hear a lot of talk these days about increasing the penetration of renewables on the electrical grid worldwide. For a couple years now, a team of researchers at Global Research and GE Energy Consulting have been working to understanding the effects that this will have on the grid. Not only that but we are also developing technologies to help integrate renewables, while maintaining or even improving the reliability and quality of the power supply. The goal of this work is to understand how to best integrate the large amounts of wind and solar planned by governments based on Renewable Portfolio Standards (RPS) and/or as a result of Feed-In Tariffs. Factors such as physical location, grid interconnection point, and characteristics of existing grid infrastructure all play a part in determining the effect of renewables on the grid. This research will help us to integrate renewables smartly in a variety of conditions so that we’ll be able to maximize the benefit from each installation.
Right now only about 0.1% of the power generated in the U.S. is from solar energy, and about 2% is generated from wind. At first glance it appears that there should be nothing to concern ourselves with given the relatively small amount of power generated by renewables. However, the picture changes dramatically when we look at regions in the western United States. For example, we are currently working with Arizona Public Service and Arizona State University to study a feeder in Flagstaff, AZ, which will potentially get more than 40% of its power from photovoltaics (PV) by the end of 2011! Although national penetrations will likely remain low for a number of years, areas with locally high penetration are already seeing the effect of this increase in PV on their power systems.
In order to best integrate PV and other renewables into the grid we need to approach the problem from several angles. We look to solve or eliminate the negative effects that can be brought on by adding a lot of intermittent generation without the appropriate hardware and/or controls. We also look to increase the amount of power delivered to the grid from solar generators by increasing the efficiency and reliability of the generation systems. Finally we look to Smart Grid technologies to increase the overall efficiency and reliability of power supplied with renewables. We do this by employing advanced technologies that can help us to integrate locally high penetrations of PV while simultaneously maintaining, and even improving, the quality and reliability of the power delivered by our electrical grid.
Until recently most of the conversation around grid integration of renewables has been centered on wind. The wind industry is significantly ahead of the solar industry in terms of installed capacity and cost per unit of energy generated, and GE has had a large presence in the wind industry for some time. However, the solar industry is growing rapidly and the GE solar business is growing along with it. Traditionally people have tended to look at wind grid integration issues and enabling technologies and assume that the solutions for solar were nearly identical. Today we see that this isn’t always the case, and the rapid growth of the solar industry has put a spotlight on the unique issues and opportunities presented by locally high-penetration solar deployment.
Most wind generation is integrated at the transmission level. Wind is connected to the grid in much the same way as more traditional power generating plants that rely on coal, nuclear power, or natural gas. Solar generation on the other hand tends to be integrated on the distribution network, closer to the load that it’s powering and present in much smaller sizes but in much higher quantities. For example, a typical wind power plant in Texas might produce 50MW and take up over 2,000 acres. A utility-scale solar plant may only be 10MW in size and take up around 80 acres. Smaller-scale solar (around 5kW for a residential installation to 500kW for a large commercial installation) is also very common, while these sizes are much less common for wind. These differences in size and integration site put different requirements on the technology needed to most effectively integrate wind and solar into the electrical grid. Today our wind and solar grid integration teams are working on technologies tailored to their unique circumstances while sharing solutions and innovations wherever possible.
This is a very exciting time for renewables, especially in the area of grid integration. Smart Grid is helping us to explore areas of interaction between the grid and power source that were not previously explored this deeply. The research being done in this area today will help us to get to much higher levels of renewable penetration in years to come, and we are very excited to have the opportunity to work in this growing and dynamic area.