Gabriele Comodi

Multi-apartment residential microgrid monitoring system based on kernel canonical variate analysis

In the residential energy sector there is a growing interest in smart energy management systems able to monitor, manage and minimize energy consumption. A key factor to curb household energy consumption is the amendment of occupant erroneous behaviors and systems malfunctioning. In this scenario energy efficiency benefits can be either amplified or neutralized by, respectively, good or bad practices carried out by end users. Authors propose a diagnostic system for a residential microgrid application able to detect faults and occupant bad behaviors. In particular a nonlinear monitoring method, based on kernel canonical variate analysis, is developed. To overcome the normality assumption regarding the signals probability distribution, Upper Control Limits are derived from the estimated Probability Density Function through Kernel Density Estimation. The proposed method, applied to a smart residential microgrid, is tested on experimental data acquired from July 2012 to October 2013.

Micro Gas Turbines

Conventional gas turbines (GTs) range from a size of one or a few MWe to more than 350 MWe (GTW, 2009). Those at the small end of the range are commonly used in industrial applications, for mechanical or onsite electrical power production, while the larger ones are usually installed in large-scale electrical power plants, often in combined cycle plants, and are typically located far away from the consuming region. In the future distributed energy systems based on small local power plants are likely to spread; since they lie close to the final users, they reduce electrical transport losses, and make thermal energy recovery profitable both in energy-related and in economic terms (Papermans et al., 2005; IEA, 2002). These benefits explain the increasing interest in smallsize generation systems. Recently, gas turbines < 1 MWe, defined as micro gas turbines (MGTs), have appeared on the market. MGTs are different from large GTs and cannot therefore be considered merely as their smaller versions. Their advantages as distributed energy systems lie in their low environmental impact in terms of pollutants and in their competitive operation and maintenance (OM Zogg et al., 2007).

Micro Combined Plant With Gas Turbine and Organic Cycle

In this paper we discuss the usefulness of a bottoming cycle applied to a micro size gas turbine unit to enhance its electric performance. A commercial 100 kWe micro gas turbine is used as a topping system; a basic thermodynamic analysis is performed to define the principal characteristics of viable vapour bottoming cycles. The analysis points to a solution adopting an Organic Rankine Cycle (ORC) with R245fa as working fluid, due both to environmental constrains and to technical criteria.Copyright

Kernel canonical variate analysis based management system for monitoring and diagnosing smart homes

In the contest of household energy management, a growing interest is addressed to smart system development, able to monitor and manage resources in order to minimize wasting. One of the key factors in curbing energy consumption in the household sector is the amendment of occupant erroneous behaviours and systems malfunctioning, due to the lack of awareness of the final user. Indeed the benefits achievable with energy efficiency could be either amplified or neutralized by, respectively, good or bad practices carried out by the final users. Authors propose a diagnostic system for home energy management application able to detect faults and occupant behaviours. In particular a nonlinear monitoring method, based on Kernel Canonical Variate Analysis, is developed. To remove the assumption of normality, Upper Control Limits are derived from the estimated Probability Density Function through Kernel Density Estimation. The proposed method is applied to smart home temperature sensors to detect anomalies respect to efficient user behaviours and sensors and actuators faults. The method is tested on experimental data acquired in a real apartment.

PERFORMANCE ANALYSIS OF COGENERATIVE AND TRIGENERATIVE PLANT WITH MICROGAS-TURBINE

The paper reports on the performance analysis of cogenerative and trigenerative plants based on Micro Gas Turbines. The core of the system is a natural-gas-fuelled Turbec T100 operating on a regenerated open-air cycle. A code specifically developed by the authors to simulate the micro gas turbine in cogeneration plants, and already checked against experimental data, has been upgraded to simulate the units behavior when facing also a cooling demand (trigenerative case). For this purpose the model of a water-LiBr single-effect absorption chiller driven by hot water has been used. The analysis cover all the units application range and represent a start for its economic evaluation.

Smart home heating system malfunction and bad behavior diagnosis by Multi-Scale PCA under indoor temperature feedback control

The household sector is one of the biggest aggregate consumers and this is the reason why increasingly policies have been considering it. One of the key factors in curbing energy consumption in this sector is widely recognized to be due to erroneous behaviors and systems malfunctioning. In this context, energy management in homes is playing, and will play even more in future, a key role in increasing the final consumer awareness towards its own energy consumption and consequently in bursting its active role in smart grids. This paper highlights the economic benefits of low cost intelligent control domestic devices and identifies energy behavior, system malfunctions and improves energy efficiency. The scope is to detect and isolate different types of malfunctions and bad behaviors under an ambient temperature feedback control. The paper presents an application of Multi-Scale Principal Component Analysis to diagnose inefficient occupant behavior and systems malfunctioning and suggest good practices of energy conservation.

New Running Strategies of a STIG Power Plant for District Heating

We describe the running plan of a 5.5-MWe-STIG-plant. Located in a medium-sized town in the centre of Italy, the plant both produces electric power and partially satisfies the thermal load of a nearby city district. An account of the Italian energy market is provided and the impact of recent legislation on plant operation is analysed. The liberalization of the Italian energy market in 1999 has significantly affected the technical and economic scenario for both existing and future power plants. As an example, we analyse the effects of liberalization on the overall performances of the plant described herein as well as the main changes in its running-strategies. A better economic result is shown to be possible in the new scenario mainly thanks to plant flexibility when operating as CHP (Combined Heat and Power) unit. The pursuit of optimum economic performance however prevents the plant from working at its best energetic efficiency.Copyright

A new open-source Energy Management framework: Functional description and preliminary results

In this paper, a new open-source SW framework for energy management is presented. Its name is rEMpy, which stands for residential Energy Management in python. The framework has a modular structure and it is composed by an optimal scheduler, a user interface, a prediction module and the building thermal model. Unlike most of the EMs in literature, rEMpy is open-source, can be fully customized (in terms of tasks, modules and algorithms) and integrates in real-time a thermal modelling software. In this contribution, an overview of the rEMpy and its constitutive parts is given first, followed by a detailed description of the rEMpy modules and the communication system. The Computational Intelligence algorithms which perform forecasting, thermal modelling and optimal scheduling are also presented. The performance of rEMpy is finally evaluated in two case studies with different heating technologies and the results are reported and discussed.

Cogeneration Micro Turbine Fuelled by Solid Biomass: A Technical-Economic Study for Italy

The paper presents part of the results of two studies, the European “Radar” (Raising Awareness on renewable energy Developing Agro-eneRgetic chain models) Project and the “Energy and environmental plan for the consortium of the municipalities of the Esino-Frasassi mountain area”, conducted in an area in central Italy. The area is characterized by huge forestry biomass resources and by substantial amounts of agricultural residues. The work presents a technical-economic study of a cogeneration plant using a solid biomass-fuelled micro turbine as the prime mover. The energy conversion of solid biomass can be achieved with different technologies, e.g. organic Rankine cycles, micro turbines with an external combustion chamber, or Stirling engines. The choice of the conversion system depends mainly on biomass availability and on the level of user demand. Of the conversion technologies mentioned above, the micro turbine is suitable to meet the requirements of the cogeneration plant examined here, which is applied to a low thermal demand public building. The work describes a micro turbine based on a regenerative Brayton cycle endowed with an external combustion chamber. The inlet air, after being compressed, passes through a regenerator and then through an external furnace fuelled by solid biomass, where it is further heated, and finally expands through the turbine. The outlet air of the turbine, before being funnelled through the chimney, passes through the regenerator and subsequently through a dry kiln, thereby reducing the humidity of the solid biomass. The micro turbine studied produces 75 kWe and 300 kWt. The biomass is made up of olive tree prunings. After the technical analysis, an economic study stresses the critical role of incentives systems (herein provided by the Italian legislation) in making the technology appealing to investors in renewable energy solutions. The energy and economic analysis considers different combinations of three different amounts of annual operation hours, of two operating modes (with/without cogeneration) and three purchase prices of the solid biomass. The incentives mechanism considered is the Feed-In Tariff (FiT) granted by the Italian legislation for plants < 1 MWe. The economic analysis highlights some influential factors for solid biomass-fuelled systems: contract with fuel suppliers, biomass price, availability, transportation, storage, and processing, and plant location. In particular, the purchase price of solid biomass is substantially negotiated between the manager of the energy conversion plant and suppliers. The work demonstrates the crucial role of the incentives mechanisms for economic sustainability; the strong influence of biomass price on investment profitability; and the role of cogeneration in further shortening the payback period.Copyright