Wind and Wind Power Ramp Variability over Northern Mexico

Abstract

The seasonal and diurnal variability of the wind resource in Northern Mexico is examined. Fourteen weather stations were grouped according to the terrain morphology and weather systems that affect the region to evaluate the impact on wind ramps and high wind persistent events. Four areas driven by weather systems seasonality are identified. Wind power ramps and persistent generation events are produced by cold fronts in winter, while mesoscale convective systems and local circulations are dominant in summer. Moreover, the 2013 wind forecast of the Rapid Refresh Model (RAP) and the North American Mesoscale Forecast System (NAM) forecast systems were also assessed. In general, both systems have less ability to predict mesoscale events and local circulations over complex topography, underestimating strong winds and overestimating weak winds. Wind forecast variations in the mesoscale range are smoother than observations due to the effects of spatial and temporal averaging, producing fewer wind power ramps and longer lasting generation events. The study carried out shows the importance of evaluating operational models in terms of wind variability, wind power ramps and persistence events to improve the regional wind forecast. The characteristics of weather systems and topography of Mexico requires model refinements for proper management of the wind resource.

Wind-Ramp Predictability

“…Statistical correction of model outputs to local condi-tions was assessed through simple bias correction and QM correction methods. Forecasted NAM no-ramps are more frequent than observed ones, and can produce long-lasting lowgeneration events in the region as discovered in [12]. Both statistical correction methods reduce the difference between the frequencies of the predicted ramps and the observed ramps in the range of −1 to 1 m/s, which leads to an improvement in the simulation of wind ramps and low-generation events.…”

“…The spectral peak in 1 × 10 −5 Hz of sea-breeze circulation is higher than the observed in middle latitudes. The appropriated prediction of these weather systems is important in spring and summer for a better representation of wind and wind ramps as mentioned by Pereyra-Castro et al [12]. Near-surface diurnal and sub-diurnal wind maxima decrease slightly with height, they become less relevant as the wind rotor is far from the surface.…”

“…Understanding the weather systems that generate wind ramps at specific locations can be helpful for designing a model configuration that reproduces adequately weather event characteristics. Middle-latitude systems are the main weather systems that produce large wind-speed changes in winter in Mexico [12]. However, a common issue in the prediction of wind ramps is their magnitude and timing.…”

“…On the other hand, predictability in summer is low because the systems that originate the ramps are mesoscale systems such as valley-mountain and sea-land breezes or Mesoscale Convective Systems [12]. Synoptic systems dominate the weather in winter and they can be forecasted days in advance with good accuracy.…”