WoT (Web of Things) for Energy Management in a Smart Grid-Connected Home

Introduction Increases in recent times in electricity costs and in associated emissions of greenhouse gases are having an impact on societies to adopt business and lifestyle strategies based on sustainability practices. The emergence of the smart grid (Xinghuo et al., 2011) facilitates both suppliers and consumers of electricity in reducing carbon footprint and improving the reliability and efficiency of electricity generation, distribution and utilization. The smart grid unifies recent developments in the electrical power area with those in information and communication technologies (ICT) to bring to bear changes to business practices and life styles of consumers. The smart grid recognizes the distributed nature of electricity industry and the unifying power of the ICT. Traditional power grids consist of (i) large-scale electricity generators that are located within easy reach of energy resources, (ii) highvoltage transmission lines to bring bulk electricity to load centres that are close to loads, such as industries, cities, townships etc., and (iii) lower voltage distribution networks which in turn distribute electrical power to smaller consumers of electricity. Unlike such traditional power grids, smart grids have distributed energy generation that encompasses both centrally-located large-scale generators with ratings of 100's of megawatts (MWs) and many geographically distributed smaller generators of widely varying sizes from 10's of MWs that use fossil fuels and renewables to a few kilo watts (kW) that may be solar photo voltaic (PV) panels mounted on the roof of a small house. [FIGURE 1 OMITTED] Several geographically distributed power generators need to be integrated into the smart grid, recognizing the varying capacities, characteristics and technologies associated with generators (Figure 1). Electricity generated using renewable energy sources, such as photovoltaic (PV) solar panels and wind turbines, is variable depending upon the season, weather conditions and the period of any given day. This variability has a strong influence on the delivery of reliable power to consumers. Storage of electrical energy to dampen the effects of variability in the power from renewables is therefore an important aspect of the smart grid. Various types of energy storage: pumped hydro storage, batteries, fuel cells, flywheels etc. need to be integrated into a smart grid. Such distributed energy storages in the grid may serve different networks within the grid so that they continue to operate as self-powered islands during outages resulting from natural causes or system faults (Nourai & Keane, 2010). The electricity generated by solar PV panels and by some wind generators is in the form of direct current (DC). This DC power must be converted (or inverted) to make alternating current (AC) power to enable connection to an AC smart grid. Smart grids need smart inverters with controls to maximise renewable power utilization, and to supply power to either the local load and/or the grid (Xinghuo et al., 2011). The smart grid needs to integrate the action of generators, energy suppliers and customers. The smart grid must provide suitable multi-way communication of relevant information between various business actors associated with the grid. The smart grid includes even a small household as a business actor into its business model because a household contributes towards sustainable business outcomes. There are many research papers on smart grids with a focus on large power systems (Brown, 2008; Ipakchi & Albuyeh, 2009; and Farhangi, 2010) that emphasize the importance of pervasive control and monitoring requirements in a smart grid. They point out the convergence of ICT with power system engineering. There are also many publications (Guinard, 2011; Kamilaris, et al., 2011) that deal with energy management at household levels using the ICT strategy, such as Web of things. …