بررسی تنگناهای الکتریکی در سطح فیدر برای ساختمان های مسکونی انرژی صفر شبکه ای توسط شبیه سازی سیستم یکپارچه

Recent European communications focus on the enforcement that by 2020 all new buildings are nearly Zero-Energy Buildings (ZEBs) and on the deployment of a European Smart Grid. The presented work focuses on assessing the electrical challenges at neighborhood level of an building stock evolving towards ZEBs, and identifying the resulting challenge in multidisciplinary dynamic simulation models required to perform this assessment. A tool for Integrated District Energy Assessment by Simulation (IDEAS) is developed. This IDEAS tool allows simultaneous transient simulation of thermal and electrical systems at both building and feeder level. Residential ZEBs show a self-consumption of locally generated photovoltaic (PV) electricity of 26 ± 4% at building level. Resulting feeder voltage fluctuations and possible transformer overload are quantified as bottlenecks. When all dwellings are intended to achieve a ZEB status, (i) a fraction of 14–47% of local PV supply is wasted by inverter curtailing depending on the feeder strength, while (ii) the peak transformer load is found to be 3.3 kVA per dwelling which may affect power security in existing feeder designs.

World-wide 38% of the total energy use is used for operating the building stock [1]. To reduce its environmental impact and economical consequences, the European directive 2002/91/EC [2] on energy performance of buildings has been introduced stating energy benchmarks and goals at the level of individual buildings. A recent European recast 2010/31/EU [3] obliges all member regions to enforce that by 2020 ‘all new buildings are nearly Zero-Energy Buildings’ (ZEBs). Although the definition of a nearly-ZEB is not elaborated within this recast, it aims to achieve a combination of energy efficiency and integration of local renewable energy sources. The non-simultaneity between local energy demand and supply may strongly affect the power quality at feeder level – i.e. neighborhood level – of an electricity distribution network. As such, large scale integration of ZEBs in particular and renewable electricity generation in general will require well developed solutions in the form of energy storage, demand side management or both: As such, with the recent communications of the European Commission on the deployment of a European Smart Grid [4] two crucial domains, i.e. climate change and security of power supply, become strongly linked. Within this framework, the presented paper has a dual focus: (i) assessing the electrical challenges and impact at feeder level of an building stock evolving towards nearly-ZEBs and (ii) identifying the associated challenge in the development of dynamic simulation models at this level which are required to perform this multidisciplinary assessment.

A tool for Integrated District Energy Assessment by Simulation (IDEAS) is developed and presented, and used for assessing the electrical challenges at feeder level of a building stock evolving towards ZEBs. This IDEAS tool allows simultaneous simulation of thermal and electrical processes at both building and feeder level. The tool combines detailed bottom-up statistical and engineering modeling, allowing to encompass occupant behavior, the inclusion of new technologies, and quantification of end-use energy efficiencies based on dynamic simulation. A set of residential net ZEBs is implemented in the IDEAS tool. The model at feeder level is used to assess electrical bottlenecks not taken into account in common building energy studies at the level of an individual building. Their annual household electrical energy consumption is found between 1.8 and 5.2 MWh, whereas the resulting total annual energy use for SH and DHW is found between 0.7 and 1.5 MWh. The total annual energy use is compensated by a BIPV system with a capacity of 2.2–7.1 kWp. The modeled dwellings show a self-consumption of locally generated PV electrical energy of 26 ± 4% at building level and 33% at neighborhood level. Resulting feeder voltage fluctuations and possible transformer overload are identified and quantified as bottlenecks in existing feeder designs. First, a fraction of 14–47% of expected local PV supply at feeder level is wasted by inverter curtailing when all dwellings are intended to achieve a level of net ZEB. At building level, these values rise up to a fraction of 41–68%. Second, the feeder peak load is found to be 3.3 kVA per dwelling when inverter curtailing is limited, which may affect power security in existing feeder designs.