The challenges of integrating a high proportion of intermittent wind power to the grid are well known, but now a recent study has found that when the system is equipped with the appropriate modern plant controls, wind applications can substantially enhance grid resiliency due to their quick response ability.
The study from GE Energy and the US National Renewable Energy Laboratory (NREL) modeled the country's Eastern Interconnection – an AC power grid reaching from Central Canada eastward to the Atlantic coast (excluding Québec), south to Florida and west to the foot of the Rockies (excluding most of Texas), and one of the largest electrical systems in the world.
25% wind penetration
For modelling purposes, 68GW of wind production was added across the Interconnection, except the Southeast Electric Reliability Corporation (SERC) and the Florida Reliability Coordinating Council (FRCC) regions. This represents an instantaneous penetration of about 40% where the wind was added, and of 25% for the Interconnection as a whole.
Among the results, the study found the overall frequency response of the Eastern Interconnection to a large system event is above the current frequency response obligation. None of the conditions examined, including cases with up to 40% wind generation, resulted in underfrequency load shedding or other stability problems. However, the study did not verify performance of individual regions or balancing authorities.
Other key findings:
●The fraction of generation providing governor control must be maintained above a minimum level, of the order of 30% – consistent with other findings
● Governor withdrawal on thermal plants causes a degradation in frequency response – roughly 44% degradation for the case with about 30% of the generation participating in governor control
● Governor response from wind plants can provide a significant primary frequency response, with a systemic benefit up to several times greater, per megawatt, than that in the synchronous fleet
● Inertial controls on wind plants can improve the frequency nadir
● Damping of inter-area oscillations in the Interconnection tended to improve with wind penetration. However, further analysis is necessary to determine whether this is due to the increasing wind penetration, the associated decommitment of thermal generation, or modeling inaccuracies.
Lessons for renewable integration in Europe
Although the study focused on one region, GE believes the findings are more widely applicable.
“While GE's study considered the impact of wind power on the Eastern Interconnection of the US, the lessons we've learned can be applied in Europe and around the globe,” said Nicholas Miller, lead author of the study and senior technical director for GE's Energy Consulting business. “The conclusions demonstrate that wind power can be more effective in maintaining frequency than thermal generation when wind farms are equipped with grid friendly controls. These findings should show that the future of wind energy is bright and it will continue to play a larger role in the power we consume.”