Luis Rodrigues

Impact of Weather Regimes on the Wind Power Ramp Forecast in Portugal

Short-term forecasting and diagnostic tools for severe changes of wind power production (power ramps) may provide reliable information for a secure power system operation at a small cost. Understanding the underlying role of the synoptic weather regimes (WRs) in triggering the wind power ramp events can be an added value to improve and complement the current forecast techniques. This work identifies and classifies the WRs over mainland Portugal associated with the occurrence of severe wind power ramps. The most representative WRs are identified on compressed surface level atmospheric data using principal component analysis by applying K-means clustering. The results show a strong association between some synoptic circulation patterns and step variations of the wind power production indicating the possibility to identify certain WRs that are prone to trigger severe wind power ramps, thus opening the possibility for future development of diagnostic warning systems for system operators use.

Integration of renewable sources in the electric system using Virtual Renewable Power Plants

The concept of “Virtual Renewable Power Plants - VRPP” enables several positive factors for the electric integration of Renewable Energy Sources (RES), namely (a) the smoothing of time based fluctuation of the power delivered by the RES, (b) the use of the natural complementary of renewable resources availability (c) the establishment of synergies between different RES as well as the combination of their production. The present work aims to identify the synergies between wind and photovoltaic (PV) plants, regarding their daily profiles l complementarity and resource availability; as well as the technical and economic added value of a VRPP. Results show an increase of 5.3% in the capacity factor when 2 MWp of PV is added to an 8 MW wind farm, considering all infrastructural capacity limits. Moreover, additional results include the characterization and optimization of hybrid virtual wind-PV plants production profile.

Simulation of a-Si PV system linked to the grid by DC-DC boost and two-level converter

This paper is about a PV system linked to the electric grid by power electronic converters. The modeling for the converters emulates the association of a DC-DC boost with a two-level power inverter in order to follow the performance of a testing commercial inverter employed on an experimental system. It is used pulse width modulation by sliding mode control associated with space vector modulation for control the boost and the inverter. The PV system is described by the five parameters equivalent circuit and parameter identification is carried out. Maximum power point tracking is implemented by a ∂P/∂V procedure. Simulation studies are performed and a comparison with the testing experimental system is presented.

A Spatiotemporal Methodology for Deep Offshore Resource Assessment

Reliable wind measurement campaigns needed to address deep offshore wind energy deployment are constrained by their prohibitive installation and maintenance costs. Floating LIDAR systems are a viable alternative to bottom fixed met masts, although have survivability problems during storm seasons. This chapter presents a methodology, based on already well-established standards, able to reduce the offshore measurement campaigns duration by relating them with reliable and low-cost coastal measurements. A two-step calibration procedure, spatiotemporal, is presented to obtain an accurate characterization of the wind resource in deep offshore regions taking into account the time shift between the two measurement points associated with the different atmospheric phenomena propagation. The methodology is applied in two experimental case studies: the first one deals with measurements taken by a LIDAR installed on an islet (10 km away from the coast), while in the second case study a LIDAR system is mounted on a buoy in a deep offshore region. Results show that the added temporal calibration step is gradually more important as the distance between the measurements points increases. Precision enhancements on the order of 4–5 % were observed in the expected annual energy production for a given offshore site. The proposed calibration procedures presented can be applied in many phases of the offshore development: resource assessment, power performance evaluation and even for completion of missing data in a measurement campaign.