Frequency Response of the US Eastern Interconnection Under Conditions of High Wind and Solar Generation

Frequency response, the response of the power system to large, sudden mismatches between generation and load, has recently been garnering considerable attention across all three interconnections in the US. This paper reports and builds upon the results of a study that was specifically designed to investigate the frequency response of the Eastern Interconnection (EI) due to large loss-of-generation events of the type targeted by NERC Standard BAL-003 Frequency Response and Bias, under possible future system conditions with high levels of wind generation. The main goals of the foundational work were to • create a realistic EI model for examining frequency, • illustrate overall system frequency response, • investigate the possible impact of large amounts of wind generation, and • examine means to improve EI frequency response, with the use of active power controls on wind plants. Simulations focused on the trip of multiple thermal plants totaling 4,455 MW. To examine the possible impact of high levels of wind penetration on the EI, new wind generation of approximately 85GW rating, operating at 68GW production, was added for an instantaneous penetration of about 25%. Key findings and recommendations of the foundational work are: • The dynamic model of the EI can be adjusted to more closely capture observed behavior. • The overall frequency response of the Eastern Interconnection is adequate for the cases examined. Work performed under sponsorship of US DOE, administered through National Renewable Energy Laboratory (NREL)• The fraction of generation providing governor control must be maintained above a minimum level. • Governor response from wind plants can provide significant primary frequency response. • Inertial controls on wind plants can improve frequency nadir. New insights included with this paper address implications of concurrent rapid development of solar generation in the EI. Further displacement of fossil generation by new solar generation has the potential to impact frequency response of the interconnection, and to introduce additional considerations for interregional operational strategies.