Optimal strategies for wind turbine environmental curtailment

Abstract

Wind turbine curtailment is oftentimes required as a means to mitigate environmental impacts of a wind energy installation. For example, curtailment may be required to satisfy constraints on the occurrence of shadow flicker on nearby homes or to reduce wildlife fatalities below a certain limit. This paper introduces an optimal curtailment strategy, which seeks to maximize wind plant revenue while meeting imposed environmental constraints by intelligently selecting curtailment times. To formulate the problem, a discrete set of curtailment decision times is defined, and long-term forecast data are used to predict demand-weighted power production at each time.Dynamic programming is used in conjunction with in situ meteorological sensors to compute the probabilistically optimal curtailment decision in real time. By leveraging both forecast data and real-time measurements, the algorithm ensures that the constraint budget is expended strategically, curtailing when revenue is low and saving operating hours for times when revenue is likely to be higher. Through a series of simulation studies involving shadow flicker constraints, algorithm performance is characterized and compared with two simpler approaches: a greedy scheme and a threshold-based scheme. These studies highlight the benefit of the optimal algorithm as well as the performance tradeoffs inherent in the three different solution approaches. Overall, the dynamic programming algorithm is shown to exhibit significant benefits in cases where sufficient meteorological and demand data are available. K E Y W O R D S Curtailment, Optimal Control 1 | INTRODUCTION Over the past several decades, wind energy development in the United States and other developed countries has primarily targeted sparsely populated areas with large wind resource, readily available transmission interconnects, and minimal presence of vulnerable wildlife.Many of these ideal locations for onshore wind have already been successfully developed, and thus, new activities are focusing on locations closer to populated areas. A major challenge that arises during these development activities is community acceptance and adherence to relevant wildlife regulations. Wind farms impact local residences and wildlife through sound emissions, shadow flicker, visual impact, and encroachment on the habitats of birds, bats, and other species. As a result, wind energy developers are spending increasing effort working with communities and permitting authorities to mitigate these impacts and gain community buy-in for development activities. These mitigation steps oftentimes involve curtailing turbine operation at times when they impose negative impacts on the community or wildlife population-this is sometimes deemed "environmental curtailment." For instance, curtailment may be enforced during certain hours of the night to avoid bat fatalities. 1-3 As another example, if a turbine imposes shadow flicker on a residence beyond a mutually agreed accepted limit, the operator may be required to curtail turbine operation when...

Reconciling climate action with the need for biodiversity protection, restoration and rehabilitation

“…Impacts to birds and bats could be potentially mitigated during operations; however, these are less well developed. Temporary curtailment of turbines during high-risk conditions for bat and bird collisions may help to reduce fatalities (Arnett and May, 2016;Lagrange et al, 2013;Smallwood and Bell, 2020) without compromising turbine performance and energy output (Rogers, 2020).…”