Assessing micro-generation’s and non-linear loads’ impact in the power quality of low voltage distribution networks

Distribution 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

Modelling the impact of micro generation on the electrical distribution system

In the UK and elsewhere there is considerable debate as to the future form of the electricity distribution system. The coming years will see a rise in the amount of micro-generation connected to the network at low voltages and the emergence of highly-distributed power systems (HDPS). However, there is considerable uncertainty as to the impact that this micro-generation will have on the quality of power supplied to our homes or to the stability of the electricity system as a whole. To address these engineering challenges the UK Engineering and Physical Sciences Research Council (EPSRC) is funding a three year research programme featuring a multi-disciplinary team from a variety of UK Universities: Supergen HDPS. This paper documents one piece of work emerging from the consortium, where a multi-tool approach is used to analyse the impact of micro-generation on the electricity system. This used a building simulation tool to produce electrical generation profiles for domestic cogeneration device models. These, along with profiles produced for other micro-generation technology models and electrical load profiles are then replicated and aggregated using a customised statistical approach. The profiles were then used as boundary conditions for a set of electrical load flow simulations on a model of a section of real network, where the number of microgenerators was varied according to different scenarios for the future of the UK electricity grid. The results indicate that a significant number of micro-generation devices can be accommodated before any power quality problems arise, however this is dependent upon maintaining a robust central grid

Climate Change: the citizen's agenda Evidence to Environment, Food and Rural Affairs Committee

i). This paper summarises some results of research by the Open University of the key influences on the adoption – and non-adoption – by mainly environmentally-concerned UK citizens of low and zero carbon (LZC) technologies. These include energy efficiency measures (such as loft insulation, condensing boilers and compact fluorescent lamps covered by the Energy Efficiency Commitment) and micro-generation energy technologies (such as solar water heating, photovoltaics and micro-wind turbines included in the DTI's Clear Skies scheme and Low Carbon Buildings Programme). The research also includes the benefits and problems experienced by the citizens who adopted these LZC technologies, plus ideas and policies for overcoming the barriers to their adoption and their effective use in reducing carbon emissions. The tables in the paper show that each LZC technology has different drivers, barriers, benefits and problems and hence ideas and policies for improvements, but there are some common factors that affect the different technologies. ii) The main driver for citizen adoption of LZC technologies is reducing fuel bills and/or saving energy in the context of rising fuel prices. Another key driver for adoption of LZC technologies is environmental concern (esp. climate change and nature conservation), at least for the mainly 'greener' citizens we surveyed. iii) The barriers to adoption vary widely depending on the technology concerned and go beyond the well-known financial issues. Examples of significant barriers to the adoption of energy efficiency measures include peoples' concerns about irritant fibres in loft insulation materials, needing to clear the loft, and loss of loft storage space when installing the recommended thickness of insulation; the reputation of condensing boilers among installers and consumers for unreliability and shorter life; and the size and perceived ugliness of compact fluorescent lamps, and a failure to communicate improvements in CFL design and technology since their introduction. However, even for environmentally concerned citizens, capital cost is a major barrier to adoption of micro-generation technologies, together with the uncertain performance and reliability of innovative technologies. iv) The benefits of insulation are reported (even by non fuel-poor citizens) largely in terms of warmer homes rather than in reduced energy consumption, i.e. the 'rebound effect' of insulation could be higher than the figure assumed for the Energy Efficiency Commitment. In contrast, improved heating controls when used properly and condensing boilers appear to have little rebound effect and so should help more directly to reduce carbon emissions. Energy efficient lighting appears to involve a relatively small rebound effect, as some users choose to leave CFLs switched on longer and/or may install additional CFL lighting. (v) The micro-generation technologies as well as reducing carbon emissions, offer citizens who can afford to install them (for whom grants were only a relatively minor driver) great pleasure in using renewable energy as well as focusing their attention on saving energy. vi) To encourage the widespread adoption and effective use of these LZC technologies requires different actions and policies tailored to the specific technologies: e.g. allowing use of eco-friendly materials in subsidised loft insulation schemes; designing and installing user-friendly controls that provide feedback on energy used or saved; energy companies offering financing packages to install micro-generation systems; and regulations and standards guaranteeing the performance, reliability and durability of micro-generation technologies

Algorithms for balancing demand-side load and micro-generation in Islanded Operation

Micro-generators are devices installed in houses pro-\ud ducing electricity at kilowatt level. These appliances can\ud increase energy efficiency significantly, especially when\ud their runtime is optimized. During power outages micro-\ud generators can supply critical systems and decrease dis-\ud comfort.\ud In this paper a model of the domestic electricity infras-\ud tructure of a house is derived and first versions of algo-\ud rithms for load/generation balancing during a power cut\ud are developed. In this context a microCHP device, produc-\ud ing heat and electricity at the same time with a high effi-\ud ciency, is used as micro-generator.\ud The model and the algorithms are incorporated in a sim-\ud ulator, which is used to study the effect of the algorithms for\ud load/generation balancing. The results show that with some\ud extra hardware all appliances in a house can be supplied,\ud however not always at the preferred time.\u

The implementation of discrete demand management algorithms within energy systems modelling

Traditionally, demand side management (DSM) programs have been driven by utilities. With the prospect of growth in the utilization of building-integrated micro-generation, DSM offers opportunities for additional energy savings and CO2 emission reductions through better utilisation of local renewable energy resources. This paper examines the feasibility of using discreet demand management (DDM) to improve the supply/demand match. For many combinations of micro-generation and DDM controls, it is necessary to know the environmental conditions (i.e. temperatures and lighting levels) within the buildings being modelled. One method would be to embed all the renewable energy technologies and DDM algorithms within a detailed simulation program. An alternative method, investigated in this study, involves coupling two existing tools: a dynamic building simulation program (ESP-r) and a demand/supply matching program (MERIT) that incorporates DDM algorithms and renewable energy system technologies. These two programs interact at the time-step level and exchange calculated parameters (relating to loads, supply potentials and prevailing environmental conditions) to enable an evaluation of DDM techniques in terms of energy saving and occupant impact. This paper describes the technique and presents simulation results relating to a number of building cases

Energy storage : the route to liberation from the fossil fuel economy?

If a low-carbon energy strategy is to be developed up to 2050, renewable energy sources will need to be deployed on a large scale against a scenario of increasing global energy demand. Renewables will vary from large-scale regional wind and marine clusters to more localised 'micro' generation. If a low-carbon strategy is to be successful, automotive transport will also need to be linked to the renewable infrastructure. Both of these need the development of efficient and viable energy storage

Uptake of Micro-generation among Small Organisations in the Camden Climate Change Alliance

The recent introduction of feed-in tariffs and renewable heat incentives in the UK has provided a new financial incentive for the installation of micro-generation, but so far there has been limited research on its uptake in small organisations. Our research starts to fill that gap by presenting a unique case study of the Camden Climate Change Alliance (CCCA) of small organisations to explore the perceived barriers and incentives to installation among members. We assess how micro-generation is viewed in the context of wider environmental measures to discover that ‘green marketing’ provides a strong incentive while upfront costs remain the primary barrier. Participants in the study prioritise energy efficiency over micro-generation due to shorter paybacks, which leads us to propose an Energy Hierarchy Framework model as a useful tool towards the adoption of micro-generation in SMEs and other small organisations. The CCCA is successful at enabling small organisations to participate in environmental management by offering free workshops, audits and events. As a large proportion of UK carbon emissions derive from small organisations, reductions could be achieved through the setting up of similar climate change alliances by local authorities in other areas of the country

Interactive Demand Shifting in the context of Domestic Micro-Generation

The combination of ubiquitous computing and emerging energy technologies is radically changing the home energy landscape. Domestic micro-generation, dominated by solar photovoltaic, is increasing at a rapid pace. This represents an opportunity for creating and altering energy behaviours. However, these transformations generate new challenges that we call the domestic energy gap: domestic electricity consumption and microgeneration are out of sync. Micro-generation is mainly uncontrollable production relying on weather while domestic energy consumption tends to happen mostly during the evening. This thesis focuses on understanding and supporting new domestic practices in the context of domestic solar electricity generation, looking at ‘Demand-Shifting’. Specifically, we look at how can digital tools leverage Demand-Shifting practices in the context of domestic micro-generation? Relying on a mixed-method approach, we provide a qualitative and quantitative answer with the collaboration of 38 participating households in several field studies including two spanning more than eight months. Through a deep investigation of laundry and electric mobility routines in the context of domestic micro-generation, we emphasised a natural engagement into Demand-Shifting which appeared as a complex and time-consuming task for participants which was not visible when we analysed their quantitative data. We revealed this complexity through Participatory Data Analyses, a method we designed to analyse the data in collaboration with the participating householders. This provided us with a comprehensive view of the relationship between domestic micro-generation and daily routines. Finally, we highlight the need for timely and contextual support through the deployment of interventions in-the-wild. Building on discussions of our findings in perspective of the literature, we propose a conceptual framework to support domestic interactive Demand-Shifting

Sustainability of Grid-tie Micro-generation System

Both the outcomes of technical and economical feasibility analysis of a renewable based power system should be positive to achieve sustainability. Energy production or Renewable Energy Feed-in-Tariff (REFIT) cost should be lower or higher respectively than the existing grid electricity cost. As the renewable energy sources are variable and where REFIT is also applicable for the system connected to the grid, the detailed hourly time series analysis is very important. Based on this issue, in this paper, a techno-economic feasibility analysis has been performed for a PV based micro-generation system to find out the possible ways to make the micro-generation (μGen) system sustainable in low irradiation region. As a case study, the city of Dublin, Ireland has been chosen for the detailed analysis. Analysis shows how the technological improvement can help to popularize the μGen system in Ireland. The procedure can be followed by other countries as well

Network power flow analysis for a high penetration of distributed generation

Increasing numbers of very small generators are being connected to electricity distribution systems around the world. Examples include photovoltaics (PV) and gas-fired domestic-scale combined heat and power (micro-CHP) systems, with electrical outputs in the region of 1 to 2 kW. These generators are normally installed within consumers' premises and connected to the domestic electricity supply network (230 V single-phase in Europe, 120 V in North America). There is a growing need to understand and quantify the technical impact that high penetrations of such generators may have on the operation of distribution systems. This paper presents an approach to analyzing this impact together with results indicating that considerable penetrations of micro-generation can be accommodated in a typical distribution system