Coupled Atmospheric–Ice Load Model for Evaluation of Wind Plant Power Loss

Abstract

Icing is a weather phenomenon that is typical of cold climates. It impacts human activities through ice accretion on tower structures, transmission lines, and the blades of wind turbines. Icing on turbine blades, in particular, results in wind turbine performance degradation and/or safety shutdowns. The objective of this study is to explore the feasibility of using a coupled atmospheric and ice load model to simulate icing start-up, duration, and amount while also quantitatively evaluating power loss in wind plants related to icing events and mechanisms. Eight of 27 icing episodes identified for a wind plant in the Gaspé region of Québec (Canada) during the period 2008-10 were simulated using a mesoscale model (the Global Environmental Multiscale Limited-Area Model, or GEM-LAM). The simulations were verified using near-surface temperature, relative humidity, and wind speed, all of which compared well to in situ observations. Simulated wind speed, precipitation, cloud liquid water content, and median volume diameter of the droplets were used to drive ice load models to simulate the total ice load on a cylindrical structure. The three ice load models accounted for freezing rain, wet snow, and in-cloud icing, respectively, and in all three cases a sink term was added to account for melting due to radiation. The start-up and duration of ice were well captured by the coupled model, and a positive correlation was found between icing episodes and wind power reduction. This study demonstrates the improvements of the icing forecasts by using three ice load models, and provides a framework for both qualitative and quantitative evaluation of icing impact on wind turbine operations.

Projected changes to extreme freezing precipitation and design ice loads over North America based on a large ensemble of Canadian regional climate model simulations

“…Atmospheric ice accretion caused by freezing precipitation during ice storms is a frequent and major natural disturbance that can affect wind energy generation (Yang et al, 2015), urban functioning (Hauer et al, 2011;Armenakis and Nirupama, 2014), communication structures (Mulherin, 1998), the forestry sector (Proulx and Greene, 2001;Seidl et al, 2017) and electrical infrastructure (Fu et al, 2006;Rezaei et al, 2016;. This damage expresses the impact of natural hazards on urban areas, infrastructure, and other economic sectors.…”

Measurement of Atmospheric Icing and Droplets

“…When the icing process is known, it is possible to calculate the rate of icing, (d M/dt) [6]. The method has been verified in [7], [4], [35], [36], and [2] and has become a standard practice for estimating the icing rate. See the following equation:…”

“…There is a need for in situ measurements that can be used as an input to the numerical data analysis to improve the calculation and prediction of icing. The liquid water content (LWC) and the median volume diameter (MVD) of supercooled water droplets are essential parameters that are used in current icing models [2], [7].…”