Preparing the grid for large-scale renewables.
Dwayne Stradford is a transmission planning engineer at SAIC Energy, Environment & Infrastructure LLC. Previously he worked at AEP in the transmission operations section.
As many wind generation developers have done in the past, solar generation developers are now seeking to connect large-scale renewable projects to utility transmission and sub-transmission systems. Renewable portfolio standards have created a market for the construction of merchant wind and solar generation and many state renewable programs require that these plants be interconnected to distribution and sub-transmission systems to receive renewable energy credits from the state. Solar inverters are now commercially available in 500 kW and 1,000 kW sizes, and photovoltaic panel prices have fallen in recent years—which makes bulk power grid connectivity, and the associated higher interconnection costs for these solar arrays, more feasible.
Wind turbines that produce up to 3 MW per turbine are now commonplace in the United States, with more than 40,000 MW installed in the country at the end of 2010, according to the American Wind Energy Association (AWEA). Additionally, there are many planned off-shore projects that are likely to use turbines at or greater than 5 MW per turbine. The transmission interconnection queues across the country have proposed future wind and solar projects ranging from 10 MW to more than 500 MW at a site with interconnection voltage generally aligned with the size of the project—the larger the project, the higher the interconnection voltage.