Browsing by Author "Rodrigues, L."
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- Assessing micro-generation’s and non-linear loads’ impact in the power quality of low voltage distribution networksPublication . Bonifácio, Paulo; Viana, Susana; Rodrigues, L.; Estanqueiro, AnaDistribution networks face an increasing penetration of solar PV (photovoltaic) and small WTG (wind turbine generator) as well as other forms of micro-generation. To this scenario, one must add the dissemination of non-linear loads such as EV (electric vehicles). There is something in common between those loads and sources: the extensive use of power electronic converters with commutated switches. These devices may be a source of medium-to-high frequency harmonic distortion and their impact on the local distribution grid must be carefully assessed in order to evaluate their negative impacts on the network, on the existing conventional loads and also on other active devices. In this paper, methodologies to characterize effects such as: harmonics, network unbalances, damaging power line resonance conditions, and over/under voltages are described and applied to a real local grid configuration.
- Assessment of PV and wind microgeneration's impact in the power quality of low and medium voltage distribution networksPublication . Bonifácio, Paulo; Viana, Susana; Rodrigues, L.; Estanqueiro, AnaElectric power systems face an ever-growing penetration (PV) and other microgeneration as well as non-linear loads such as electric vehicles. This is a common link between these : the extensive use of power electronics converters. These devices are a source of medium-to-high frequency harmonic distortion and their impact on the local distribution grid must be carefully assessed in order to evaluation possible network unbalances, demaging power line resonance conditions, transformer core saturation and overhearing.
- Assessment of PV and wind microgeneration's impact in the power quality of low and medium voltage distribution networksPublication . Bonifácio, Paulo; Rodrigues, L.; Viana, Susana; Estanqueiro, Ana
- Certainty gain effect on wind power forecasting in the electricity market [Comunicação oral]Publication . Couto, António; Rodrigues, L.; Costa, Paula Silva; Silva, João M. Henriques da; Estanqueiro, Ana
- Contribution of energy storage for large-scale integration of variable generationPublication . Estanqueiro, Ana; Ardal, Atle Rygg; O'Dwyer, Ciara; Flynn, Damian; Huertas-Hernando, Daniel; Lew, Debra; Gomez-Lázaro, E.; Carlini, Enrico Maria; Solvang, Eivind; Ela, Erik; Kiviluoma, Juha; Rodrigues, L.; Amelin, MikaelThe amount of wind power and other timevariable non-dispatchable renewable energy sources (VRES) such as photovoltaics (PV) is rapidly increasing in the world. Several power systems in Europe are already facing a very high penetration from variable renewables which is posing concerns on the operational stability limits that are being surpassed for extreme RES generation conditions. Most transmission system operators are defining VRES limits of penetration, thus, requiring the renewable energy excess to be curtailed, exported or stored. Energy storage may play a relevant role in maximizing the long term penetration of VRES if used as a technical mean to regulate the daily, weekly and annual profiles of variable generation (VG). This paper reviews the storage technologies that are available and may be used on a power system scale and performs a cost/benefit analysis discussing their advantages and disadvantages for the integration of fastgrowing renewables, such as wind power and PV.
- Energy storage for wind integration: hydropower and other contributionsPublication . Estanqueiro, Ana; Ardal, Atle Rygg; O'Dwyer, Ciara; Flynn, Damian; Huertas-Hernando, Daniel; Lew, Debra; Gomez-Lázaro, E.; Ela, Erik; Revuelta, Javier; Kiviluoma, Juha; Rodrigues, L.; Amelin, Mikael; Holttinen, HanneleThe amount of wind power and other timevariable non-dispatchable renewable energy sources (RES) is rapidly increasing in the world. A few power systems are already facing very high penetrations from variable renewables which can surpass the systems’ consumption during no-load periods, requiring the energy excess to be curtailed, exported or stored. The limitations of electric energy storage naturally lead to the selection of the well-known form of storing potential energy in reservoirs of reversible hydropower stations, although other technologies such as heat storage are also being used successfully. This paper reviews the storage technologies that are available and may be used on a power system scale and compares their advantages and disadvantages for the integration of fast-growing renewables, such as wind power, with a special focus on the role of pumped hydro storage.
- Impact of weather regimes on the wind power ramp forecastPublication . Couto, António; Costa, Paula Silva; Rodrigues, L.; Lopes, Vitor V.; Estanqueiro, AnaThe stochastic nature of wind and the continuous need to balance electric generation with demand poses serious challenges to the power system operators. The impact of large wind integration into the power system is mitigated by decreasing the uncertainty associated with wind forecasts. In particular, the forecast of severe wind power ramps is important due to its impact on the energy market and grid operation and planning. This study proposes to classify the weather regimes over continental Portugal associated with the severe wind power production ramps. Thus, an automated classification system is developed by combining principal components analysis and kmeans clustering to find the most representative atmospheric flow patterns near the surface. This system can tackle with the synoptic spatial variability allowing the decrease of phase and timing mismatches present in single time forecasts. Then, the patterns are linked to the wind power production. Results show that it is possible to associate weather regimes with different levels of wind power production and identify certain atmospheric circulations with a higher chance to trigger severe wind power ramps.
- Impact of weather regimes on the wind power ramp forecast in PortugalPublication . Couto, António; Costa, Paula Silva; Rodrigues, L.; Lopes, Vitor V.; Estanqueiro, AnaShort-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 plantsPublication . Rodrigues, L.; Estanqueiro, AnaThe 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.
- Optimizing the performance of renewable sources using virtual renewable power plantsPublication . Rodrigues, L.; Estanqueiro, AnaThe concept of “Virtual Renewable Power Plants - VRPP” enables several positive factors for the electric integration of Renewable Energy Sources (RES) and enables the optimization of its technical and economic performance by using the natural complementary of renewable resources availability. Moreover, the establishment of synergies between different RES contributes for the smoothing of time based fluctuation of the power delivered by the RES. The present work aims to identify the synergies between wind and photovoltaic (PV) plants, regarding their daily profiles 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 and 25% in the revenue when 2 MWp of PV are added to an 8 MW wind farm, and a potential benefit of 48% when adding a storage system of 2 MW (8 MWh), considering all infrastructural capacity limits. Moreover, the combined VRPP daily production profiles have a significantly higher correlation with the average daily load profile (0.82) than WTG (0.41) or PV (0.54) alone.