Field testing of a local wind inflow estimator and wake detector

Abstract

<jats:p>Abstract. This paper presents the field validation of a method to estimate the local wind speed on different sectors of a turbine rotor disk. Each rotating blade is used as a scanning sensor that, travelling across the rotor disk, samples the inflow. From the local speed estimates, the method can reconstruct the vertical wind shear and detect the presence and location on an impinging wake shed by an upstream wind turbine. Shear and wake awareness have multiple uses, from turbine and farm control to monitoring and forecasting. This validation study is conducted with an experimental data set obtained with two multi-MW wind turbines and a hub-tall met-mast. Practical and simple procedures are presented and demonstrated to correct for the possible miscalibration of sensors. Results indicate a very good correlation between the estimated vertical shear and the one measured by the met-mast. Additionally, the proposed method exhibits a remarkable ability to locate and track the motion of an impinging wake on an affected rotor. </jats:p>

Wind inflow observation from load harmonics: initial steps towards a field validation

“…Wind sensing refers to the general concept of using the response of the turbine to estimate characteristics of the inflow, which can be done in several different ways (Bottasso et al, 2010;Bottasso and Riboldi, 2014;Simley and Pao, 2016;Bottasso and Riboldi, 2015;Bertelè et al, 2017;Bottasso et al, 2018;Schreiber et al, 2020). Information on the inflow can support a variety of applications, including turbine and farm-level control, lifetime assessment and fatigue consumption estimation, power and wind forecasting, and others (Schreiber et al, 2020). In wind sensing, the rotor response is typically measured in the form of blade loads.…”

“…Goal of this paper is to present the application of the load-harmonic estimator to field test data collected at a test site on a 3.5 MW wind turbine and a nearby met-mast (Schreiber et al, 2020;Bertelè and Bottasso, 2020). This experimental setup is a realistic representation of the scenario outlined above, where a hub-tall met-mast is located in close proximity of a wind turbine for certification purposes.…”

“…a shear over the entire rotor disk area). For large modern rotors, half-rotor or full-rotor shears are not necessarily equal (Murphy et al, 2019;Schreiber et al, 2020). Therefore, a way is needed to extend the measurement of the inflow above the met-mast, possibly without resorting to extra wind-scanning equipment to reduce cost and complexity.…”

“…Therefore, a way is needed to extend the measurement of the inflow above the met-mast, possibly without resorting to extra wind-scanning equipment to reduce cost and complexity. This problem is solved here using yet another wind sensing method (Bottasso et al, 2018;Schreiber et al, 2016Schreiber et al, , 2020. This second approach uses blade loads to estimate the average local speed over sectors of the rotor disk; from these sector-equivalent wind speeds, one can then estimate shears, including a vertical shear defined over just the lower half of the rotor.…”

“…The sector-effective speed and load-harmonic observers have distinct characteristics, which make them somewhat complementary and applicable to different scenarios. In fact, the sector-effective observer does not need to be trained with data before it can be used, which is particularly useful in the case considered here, but can only reconstruct shears and not wind directions (Schreiber et al, 2020). On the contrary, the load-harmonic observer can reconstruct both shears and directions but needs to be trained from data, which is a potential complication.…”