No abstract

Power flow analysis of distribution networks incorporating LV consumer representation needs to be cognizant of an unbalanced load structure and the grounding network between the consumer and network operator (TNC-S earthing). In this paper, the asymmetrical 3-phase (and neutral) power flow problem is solved by a correction current injection methodology applied to a system represented by a complex admittance matrix. The correction current injection technique is adopted to adjust the power exchange of shunt elements, whose nominal admittances are included in the system admittance matrix, through suitable fringing currents in the iteration process. This methodology offers an improved and more robust alternative for asymmetrical network scenarios under unbalanced power flow conditions when compared to the standard power flow methodologies, such as the Newton-Raphson or the forward-backward sweep approaches. These well-known methods may encounter convergence issues as a consequence of the specific consumer/network earthing arrangements especially when they need to be defined throughout the network. The algorithm presented here has been applied to a 4-wire representation of a suburban distribution network within Dublin city,

No abstract

The micro-turbine wind market in cities faces significant challenges due to the complexities associated with the urban terrain but, if a renewable solution to increasing energy demand is to be achieved, energy conversion systems where populations are concentrated, that is cities, must be considered. This research evaluates the urban wind resource by employing a physically-based empirical model to link wind observations at a conventional meteorological site to those acquired at urban sites. The approach is based on urban climate research that has examined the effects of varying surface roughness on the wind-field between and above buildings. Here, this is applied to link observations at Dublin Airport, outside the urban area, to those made at an urban and suburban site in Dublin where instruments were placed near roof-level and well above roof height. The log model to describe the vertical wind profile is tested against observations made over the course of a year. It is shown to have sufficient accuracy to assess the potential for micro-turbine energy generation in cities and illustrates that the urban wind resource can be evaluated from measurements made at a nearby site, adjusted for the urban site location. HighlightsThe article investigates if a viable wind resource, worth exploiting, exists at an accessible height above a city (Dublin, Ireland) Urban climatology and the simple logarithmic profile, are employed to successfully extrapolate the wind resource at the city Airport into an associated suburban and urban location, to a height between 1.5 and 2 times the respective average building height at both locations The analysis shows that in conjunction with urban surface roughness, the urban frictional velocity must also be considered for urban wind resource modelling Other models are utilised to investigate the nature of the wind resource below the recognised lower limit of the logarithmic profile, namely the power law and a methodology primarily developed for urban air pollution modelling The research is provided a renewable energy context by considering the productivity of a commercially available wind generator. The results show that the wind resource available at roughly twice the average building height at either an urban and suburban location is worth harnessing, but within a very short height reduction, the wind resource depletion renders the consideration economically unviable.

No abstract