• Energy Research
• 2016-2025close
• ES close
• DE close
• Research Repository of Catalonia close

Inter-turn winding faults in five-phase ferrite-permanent magnet-assisted synchronous reluctance motors (fPMa-SynRMs) can lead to catastrophic consequences if not detected in a timely manner, since they can quickly progress into more severe short-circuit faults, such as coil-to-coil, phase-to-ground or phase-to-phase faults. This paper analyzes the feasibility of detecting such harmful faults in their early stage, with only one short-circuited turn, since there is a lack of works related to this topic in multi-phase fPMa-SynRMs. Two methods are tested for this purpose, the analysis of the spectral content of the zero-sequence voltage component (ZSVC) and the analysis of the stator current spectra, also known as motor current signature analysis (MCSA), which is a well-known fault diagnosis method. This paper compares the performance and sensitivity of both methods under different operating conditions. It is proven that inter-turn faults can be detected in the early stage, with the ZSVC providing more sensitivity than the MCSA method. It is also proven that the working conditions have little effect on the sensitivity of both methods. To conclude, this paper proposes two inter-turn fault indicators and the threshold values to detect such faults in the early stage, which are calculated from the spectral information of the ZSVC and the line currents.

Este Trabajo consiste en realizar un estudio sobre la penetración de energías renovables en una red de alta tensión, concretamente en la red IEEE 39-Bus System, la cual está situada en New England (EEUU). El objetivo principal es determinar el porcentaje máximo de generación renovable que puede soportar dicha red. Para realizar las simulaciones se ha usado el programa PSS/E. En primer lugar se ha hecho una explicación sobre las energías renovables y su tendencia tanto en España como en Europa. A continuación se comenta en qué consisten las conexiones de renovables a la red eléctrica y las dificultades para integrar energía renovable en dichas redes. Puesto que toda conexión a una red eléctrica debe seguir una normativa, se explican los puntos más destacados del procedimiento PO 12.2. Este procedimiento es uno de los varios códigos de conexión existentes, el cual informa sobre los requisitos mínimos de diseño, equipamiento, funcionamiento, puesta en servicio y seguridad de las instalaciones de generación y de demanda. Posteriormente se define la red eléctrica IEE 39-BUS System, en la cual se han realizado las simulaciones, así como el modelo de generador renovable que se ha usado. Finalmente se ha desarrollado la realización de las simulaciones, empezando por realizar simulaciones sin generadores renovables para observar el comportamiento de la red. Después de estas primeras simulaciones, las cuales han mostrado un resultado positivo, se han ido sustituyendo generadores convencionales por otros de renovables. La sustitución se ha hecho de manera progresiva, empezando por una penetración de renovable del 20% hasta alcanzar el 70%, por lo que se concluye que la red IEE 39-BUS System puede llegar a soportar hasta un 70% de generación renovable.

Most of the Catalonian population and urban areas are located along the Mediterranean coastal zone and for this analysis three largest Catalonia’s cities are chosen: Barcelona, Terrassa and Tarragona. Each city is a geographical representative of a different climate type according to the re-analysed Köppen-Geiger climate classification. The objective of this research is to demonstrate the effects of regional climate variations on the potential of natural ventilation (NV) application in building design. The first part of the article presents the availability of NV corresponding to yearly climate conditions applying the methodology “Climate Potential for Natural Ventilation” (CPNV). In continuation, the second analysis is calculated with building energy simulation software and displays possible refrigeration energy savings in three geographical locations. Mixed-mode (or hybrid-mode) and night-ventilation techniques are applied for the cooling process of a hypothetical low-rise office building model. Peer Reviewed

ABSTRACTWind power forecasts are useful tools for power load balancing, energy trading and wind farm operations. Long range monthly‐to‐seasonal forecasting allows the prediction of departures from average weather conditions beyond traditional weather forecast timescales, months in advance. However, it has not yet been demonstrated how these forecasts can be optimally transformed to wind power. The predictable part of a seasonal forecast is for longer monthly averages, not daily averages, but to use monthly averages misses information on variability. To investigate, here a model relating average weather conditions to average wind power output was built, based on the relationship between instantaneous wind speed and power production and incorporating fluctuations in air density due to temperature and wind speed variability. Observed monthly average power output from UK stations was used to validate the model and to investigate the optimal temporal resolution for the data used to drive the model. Multiple simulations of wind power were performed based on reanalysis data, making separate simulations based on monthly, daily and sub‐daily averages, using a distribution defined by the mean across the period to incorporate information on variability. Basing the simulation on monthly averages alone is sub‐optimal: using daily average winds gives the highest correlation against observations. No improvement over this is gained by using sub‐daily averages or including temperature variability. This signifies that to transform seasonal forecasts to wind power a compromise must be made between using the daily averages with debatable skill and the more predictable monthly averages, losing information on day‐to‐day variability.

The objective of this paper is to explain novel sustainable robotics solutions for cities. Those new proposals appear under the ECHORD++ project which is a good tool to meet academia and industry with the objective of providing innovative technological solutions. In this paper, authors explain the tool as well as the methodology to promote robotics research in urban environments, and the on-going experience will demonstrate that huge advances are made in this field. Peer Reviewed

AbstractFiscal rules are necessary to protect monetary policy from the consequences of unsustainable or active fiscal policy for inflation. Monetary unions, such as the Economic and Monetary Union (EMU), require even stronger fiscal rules to avoid free riding by regional fiscal authorities on the common monetary policy. By contrast, in a fiscal federation, the federal government internalises the effect of active regional policies on the overall price level. Federal fiscal policy contributes to price stability either by enforcing fiscal rules or by adjusting its own stance. Following Canzoneri, Cumby and Diba (2001), we test whether federal and regional governments in Germany behave in an active or passive way. We find evidence of a spillover effect of unsustainable policies on other regions. The German federal government offsets the effect on the price level by running passive policies. The Bundesbank's prime objective of price stability is therefore endorsed by fiscal policy. The results have implications for the regulation of fiscal policies in the EMU.