A. Capasso

Power system planning under uncertainty conditions. criteria for transmission network flexibility evaluation

In a free-market scenario, power system planning has to deal with a significant degree of uncertainty about time and location of generating assets expansion. A methodology for the evaluation of the attitude of the transmission system to keep up a desired standard of reliability under such uncertainty (that is, flexibility) is presented. The method, relying on the Monte Carlo simulation approach, is applied to check the effectiveness of a flexibility index, based on structural as well as operational network parameters. The results of tests carried out on simple networks and on IEEE RTS are reported showing the encouraging agreement between the probabilistic simulations and the proposed index.

A new methodology for power systems flexibility evaluation

In a free-market scenario, power system planning is affected by a significant degree of uncertainty about time and location of generating assets expansion. The paper contains a methodology for the evaluation of the flexibility, defined as the attitude of the transmission system to adapt, quickly and with limited costs, to every change, from the initial planning conditions, with a particular regard to the changes in generation. The method provides new global and local flexibility indices, based on technical and economical parameters, defined as Technical Uncertainty Scenarios Flexibility Index (T-USFI) and Technical Economical Uncertainty Scenarios Flexibility Index (TE-USFI). The T-USFI computation segment of methodology has been tested on simple networks.

A planning study on power systems of metro-transit transportation system

A simulation program, implementing a deterministic-probabilistic methodology, has been applied to an Italian railway line (Roma - Ostia Lido), whose operation is going to be changed from railway to metropolitan service. The application tasks are to point out possible critical issues of the present supplying power systems and to provide proposal about their future optimal upgrading. In order to get the real values of the main electrical parameters of electrical sub-stations (ESS) of the railway line for the simulation, an experimental survey has been performed. The paper reports the main experimental and simulation results.

Harmonics and PQ events monitoring in an electrified metro-transit system

The paper illustrates some results of a wide power quality (PQ) survey performed on the power supply installations of the metro-transit system serving the city of Rome, in Italy. The system currently includes two railway lines supplied at 1,500 V DC through several AC/DC 3.7 MW rated converters. The power supply of the system is provided at medium voltage (20 kV) from five different connections to the public grid. Fourteen electrical substations provide the total demand of about 20 MW of the system. The survey, currently still in progress, involves monitoring activities aimed at identifying possible PQ problems of various nature. Identification of typical daily patterns of harmonics distortion due to the system is even a task of the current survey.

Modelling and simulation of electric urban transportation systems with energy storage

Electrified guided vehicles are normally equipped with regenerative braking devices, while traction lines are supplied by non-reversible substation, thus allowing braking energy recovery only if nearby other vehicles are absorbing power. To enhance the effectiveness of regenerative braking, some energy storage can be installed along the line. Evaluation of its cost effectiveness requires time domain simulations, performed creating simulation models using general-purpose or specialized simulation languages. In this paper, two simulation tools are used. Their respective characteristics compared. The results obtained from both of them are also useful to evaluate the effectiveness of energy storage in a real-life urban case study.

Smart mobility for sustainability

This paper deals with an innovative concept for smart and sustainable urban mobility system. Both technical and economic aspects will be analyzed.

Bologna — Florence high speed railway line: MV emergency traction power supply, operating conditions and PQ issues

The paper illustrates the characteristics and operating modes of the emergency traction power supply system implemented on the Bologna — Florence line of the Italian High Speed network which is electrified at 2×25kV, 50Hz. The paper first describes the main characteristics of the equipment installed, the design criteria and power supply scheme. The paper goes on to outline the challenges of power quality associated with the connection of a heavy single phase load to the Medium Voltage (MV) network. The effectiveness of the installation and the evaluation of voltage unbalance compatibility levels compliance are then presented.

Individual driving style impact on traction energy consumption in railway lines: A simulation model

The study reports some energy saving evaluations in rail transit due to appropriate driving styles. Several simulations were performed on an Italian 3 kV d.c. railway line feeding high-speed and two regional trains. Different scenarios about braking phases and coasting management are reported to quantify energy saving. Evaluation of the energy recovered during the braking phases for a traffic scenario is also reported.

A measurement campaign in a metro trains deposit/maintenance and repair site for PV production optimal sizing

The paper describes a measurement campaign conducted in a metro trains deposit/maintenance and repair site for the trains in operation on the metro line B of Rome. For the measurement campaign the network analyzer Chauvin Arnoux CA 8335 has been used. The measurements were conducted by performing a monitoring on general consumption and on relevant individual loads such as office building, lighting towers, lighting, lathe, etc. The knowledge of total energy consumption and of electrical loads allows the identification of possible different strategies for energy efficiency by using the PV production. Some evaluations are also conducted on the possible use of storage energy systems.

Modelling 2×25 kV–50 Hz traction systems for power frequency studies

The paper shows the typical architecture of a 2×25 kV–50 Hz traction system, and the details that need to be considered and approximations that can safely be done, for power frequency studies. Power frequency models are important to allow simulations of long timespans, such as those needed when evaluation of trains acceleration/braking, for instance to analyse active and reactive power flows, voltages and currents. The proposed models are implemented in two ways: as data to be inputted to the well-known ATP Program, and as specific models written in the standard Modelica language. The latter can be virtually used for simulations using any of the available Modelica-capable simulation tools; moreover, the power of Modelica allows flexibility, expandability, scalability. A comparison between the two tools is proposed.