Mariacristina Roscia

Optimization of storage devices for regenerative braking energy in subway systems

The paper deals with the actual theme of power management in traction systems presenting a study about the use of regenerative braking energy in electric subway transportation. Storage systems on board of the vehicles or on fixed plants can give advantages both to contain the costs of the electric power and to limit power losses along the traction line. Moreover, other technical advantages can be obtained as, for example, the reduction of contact line voltage fluctuations. With reference to a real case, one of the Milan subway lines, a software program is implemented in order to simulate the electric power flow and to optimize the storage device size and control

A Matlab-Simulink flickermeter model for power quality studies

The paper deals with the representation of the flickermeter operation in the Simulink software program. This can be useful in case of simulation studies related to power plants where flicker phenomenon can rise up due to the presence of heavy disturbing loads (i.e. arc furnaces). The standard block diagram of the flickermeter is analyzed and reproduced in software blocks dedicated to the modeling of its different components. A validation procedure on a real case is adopted for testing the proposed model.

Hybrid photovoltaic system control for enhancing sustainable energy

The paper introduces hybrid photovoltaic/diesel generation systems for supplying remote power plant taking into account the enhancement of the sustainable energy. In particular a new monitoring and control device is presented in order to carry out the optimum energy flows. The application to a real case is reported and discussed at the end of the paper.

Synergy between renewable sources and electric vehicles for energy integration in distribution systems

The most important environmental impact from the Smart Grid will be the ability to easily integrate renewable energy resources (RES) and electric vehicles into the grid. Starting from the limits that the existing electricity distribution infrastructures have in accepting these kinds of electric devices, it is necessary to develop methods for planning and regulating the future networks. The paper presents a possible solution for a reliable systems integration between grid availability and the number of connected vehicles.

Voltage unbalance vulnerability areas in power systems supplying high speed railway

High speed railway loads fed by the three phase power system represent an important source of unbalance perturbation in the grid. The degree of voltage and current unbalances depends on the train motion, load condition and power system supply configuration. The present paper deals with the identification procedure of a vulnerability area in which the voltage unbalance presents values that exceed the standard limits. A case study referred to the 63 buses CIGRE network analyzed in the paper gives rise to interesting comments and discussion.

Sustainability Energy Indicators by means of Fuzzy Logic

The sustainability evaluation through fuzzy logic is based on four elements of sustainable development - energy, economy, environment and urban plan - together with institutional considerations. This analysis provides a systematic scheme for identifying the cross linkages among different indicators. The main purpose is to identify and define a set of indicators and their weights for sustainable energy development applicable worldwide and to demonstrate the practical use of the methodology as a policy tool in different cases. The goals of this work, beside the illustration of a methodology through fuzzy logic, are to define and to incorporate the Indicators into the relevant databases and to find out the analytical tools in order to use energy indicators for statistical analysis (capacity building). Detailed methodologies are provided for each of the 18 indicators and guidelines are described to assist users in the development and implementation of these indicators. These indicators will help policy makers to take the right decisions in the energy area in order to reach the environment goals.

Virtual power plant with energy storage optimized in an electricity market approach

This paper deals with the mathematical formulation and implementation of the optimization model for virtual power plants (VPPs). The daily optimized operation of the VPP is focusing on maximizing its benefit, considering VPP comprising renewable energy sources and energy storage systems, thermal engines and demand-response loads. The optimization model is tested considering two case studies of average electricity prices on the day-ahead market, each of them in four scenarios of the mix renewable energy sources. The model, analyzed on a 24 hours time horizon, is implemented and tested in GAMS. The obtained results show that the best benefit obtained by the virtual power plant owner is obtained when the energy production of analyzed available renewable energy sources is high, and the day-ahead market prices are elevated. In the present paper, the case when the power system operator constraints the exchanges with the virtual power was not considered.

Smart campus-an energy integrated approach

This paper analyzes the optimized operation of smart campus on the electricity market for maximizing his overall profit. The smart campus has the character of a virtual power plant with distributed energy resources with stochastic power and dispatchable classical generating units. The load is represented by the campus consumptions which can be shifted daily to accomplish the desired goals. This smart campus optimizes the use of electrical energy through exchanged electricity with the market and thermal energy through internal production such that to maximize his yearly profit.

Analysis of sustainable and competitive energy system

The climate change is increasingly apparent and the need to be independent for the sourcing of energy sources has led to the establishment of the European Community financing schemes to support research and development of systems in place to decrease pollution and independence from fossil fuels. One way to catch up with greater conviction this scope is the production of energy at a large scale, using renewable sources. Now, the incentives are even a fundamental element for the development and competitiveness of these systems, but it is clear that if the policy guidelines will converge in the direction of Horizon 2020, the possibility of implementing such systems will become a model easily replicable and suitable. In this context, this work aims to show how a production system that exploits solar energy, through a plant collector, can be comparable in terms of cost with other energy sources. In particular, an estimate is made of an economic system with solar collectors for the production of electrical energy, starting with the year of production and on the basis of 25 years of life of the plant.

Power quality impact of high capacity end-users

The random load variation, as in case of the arc furnaces, determines random voltage variations at the supply bus-bars., the can affect the power quality delivered to other customers, supplied by the same bus-bars. The value of the instantaneous flicker sensation S(t) is measured by means of an instrument, the so-called flickermeter. The setting-up of the flickermeter model is done in Simulink, the simulation tool, in the MATLAB environment. The present paper deals with the case study of an existing ac arc furnace facility. The 110 kV monitoring campaign was conducted using the ION 7600 equipment. The main power quality indices regarding harmonics and flicker levels are reported in the paper with reference to IEEE standards.