Wind and Solar Participation in Dynamic Frequency Regulation
Fig. 1. Frequency Responses of the EI System after a Generation Trip Event with Different Frequency Support Controls
Most major power grids around the world are experiencing an increase in wind or solar power in their generation mix. This is causing concerns over the stability of the grid and other difficulties in system operations. For example, conventional synchronous generators now play a pivotal role for system frequency support. Due to the absence of synchronization torque for most of wind and solar generations, higher penetrations of wind or solar power may gradually lead to the decrease of overall system inertia as well as the reduction of system frequency regulation capabilities.
However, the fast response speed of electronic converter devices makes it possible that some reserved wind or solar power can be injected into the power grid in a fast manner by wind or solar PV generation. This portion of fast, injected active power is able to contribute to frequency regulation of the power grid significantly if implemented with appropriate control schemes. In this project, the basic theories of fast active power control techniques of wind and solar PV generation were studied and then the user-defined wind/solar PV electrical control model with fast active power controllers were built in PSS/E. Taking advantage of the user-defined wind electrical control model, the potential contributions of wind/solar generation to the United States Eastern Interconnection (EI) frequency regulation was evaluated based on a 16,000-bus EI system dynamic model. Simulation results demonstrate that current and future wind or solar generation sources are promising in providing frequency regulation in the EI system.
 Yong Liu; Joe R. Gracia; Thomas J. King; Yilu Liu, " Frequency Regulation and Oscillation Damping Contributions of Variable-speed Wind Generators in the U.S. Eastern Interconnection (EI)," IEEE Transaction on Sustainable Energy, vol. PP, issue 99, May 2014.
 Yong Liu; Joe R. Gracia; Thomas J. King; Yilu Liu, "Active Power Control of Solar PV Generation for Large Interconnection Frequency Regulation and Oscillation Damping," International Journal of Energy Research, to be published.