Search results for "Voltage"
showing 10 items of 934 documents
Experimental study on B-spline-based modulation schemes applied in multilevel inverters for electric drive applications
2019
This work presents the design, simulation, and experimental validation of new B-Spline-based modulation techniques applied to a Multilevel Power Inverter (MPI), particularly focusing the attention on the harmonic content of the output voltages of the inverter. Simulation and experimental results are proposed and discussed, mainly describing the potential benefits, such as the increase of the multi-level operation of the converter, and drawbacks (low-order harmonics) related to the adoption of B-Spline functions for multilevel inverters applied in the field of electrical drives.
A Virtual Tool for Load Flow Analysis in a Micro-Grid
2020
This paper proposes a virtual tool for load flow analysis in energy distribution systems of micro-grids. The solution is based on a low-cost measurement architecture, which entails low-voltage power measurements in each secondary substation and a voltage measurement at the beginning of the medium voltage (MV) feeder. The proposed virtual tool periodically queries these instruments to acquire the measurements. Then, it implements a backward&ndash
The effect of the axial heat transfer on space charge accumulation phenomena in HVDC cables
2020
To date, it has been widespread accepted that the presence of space charge within the dielectric of high voltage direct current (HVDC) cables is one of the most relevant issues that limits the growing diffusion of this technology and its use at higher voltages. One of the reasons that leads to the establishment of space charge within the insulation of cables is the temperature dependence of its conductivity. Many researchers have demonstrated that high temperature drop over the insulation layer can lead to the reversal of the electric field profile. In certain conditions, this can over-stress the insulation during polarity reversal (PR) and transient over voltages (TOV) events accelerating …
Improving angle stability by switching shunt reactors in mixed overhead cable lines. An Italian 400 kV case study
2019
Stringent environmental constraints make the construction of new transmission overhead lines more and more difficult. Alternatively, today it is possible to use cable lines for high (HV) and extra-high (EHV) voltage systems. The configuration of the so-called mixed lines can create some problems in the operation of the electrical system, both during steady-state and transient conditions. In particular, the system stability is one of the main concerns when analyzing the dynamic response of power systems. In this paper, the study of angular stability of a system containing a mixed line is presented: a specific control logic applied to the shunt reactors of the mixed line is proposed as improv…
Methodologies for the Exploitation of Existing Energy Corridors. GIS Analysis and DTR Applications
2018
The exploitation of power lines currently in operation has now become a common practice among electric system operators. The construction of new power lines requires taking economic, political and social problems into consideration. This paper considers two methodologies adopted by the Italian Transmission System Operator (TSO), Terna S.p.A.: Dynamic Thermal Rating (DTR) and Laser Imaging Detection and Ranging-Geographic Information System (L-GIS). DTR systems dynamically calculate the real transport capacity of a power line. The L-GIS system allows, after the geo-referencing of the power line, the management of any interference between the line and the nearby obstacles, permitting the opti…
New High Voltage Interconnections with Islands in the Mediterranean Sea: Malta and Sicily. Analysis of the Effects on Renewable Energy Sources Integr…
2018
The present paper shows the benefits coming from the operation of the recent electrical high voltage (HV) interconnections between Sicily, Malta and mainland Italy. These new interconnections allow zonal prices of electricity considerably lower than in the past, ensuring greater flexibility to the system and a better integration of Renewable Energy Sources (RES). After briefly illustrating the two high-voltage electrical systems (Sicily and Malta), and having provided a description of the interconnection cable with Malta and its protection devices, the authors hypothesized two modes of operation (Sicily-Malta system islanded or interconnected to the rest of Europe). For the first case (isla…
Experimental Investigation on the Performances of a Multilevel Inverter Using a Field Programmable Gate Array-Based Control System
2019
The Field Programmable Gate Array (FPGA) represents a valid solution for the design of control systems for inverters adopted in many industry applications, because of both its high flexibility of use and its high-performance with respect to other types of digital controllers. In this context, this paper presents an experimental investigation on the harmonic content of the voltages produced by a three-phase, five level cascaded H-Bridge Multilevel inverter with an FPGA-based control board, aiming also to evaluate the performance of the FPGA through the implementation of the main common modulation techniques and the comparison between simulation and experimental results. The control algorithm…
A New Coupling Solution for G3-PLC Employment in MV Smart Grids
2019
This paper proposes a new coupling solution for transmitting narrowband multicarrier power line communication (PLC) signals over medium voltage (MV) power lines. The proposed system is based on an innovative PLC coupling principle, patented by the authors, which exploits the capacitive divider embedded in voltage detecting systems (VDS) already installed inside the MV switchboard. Thus, no dedicated couplers have to be installed and no switchboard modifications or energy interruptions are needed. This allows a significant cost reduction of MV PLC implementation. A first prototype of the proposed coupling system was presented in previous papers: it had a 15 kHz bandwidth useful to couple sin…
Dopant Contrast in Semiconductors as Interpretation Challenge at Imaging by Electrons
2007
Mechanisms responsible for the contrast between differently doped areas in semiconductors, which is observed in electron micrographs, is discussed as regards the key factors determining the sign and magnitude of the contrast. Experimental data obtained by means of the scanning electron microscope (SEM), scanning low energy electron microscope and photoelectron emission microscope are reviewed together with hints following from them for compilation of a model of the contrast mechanism.
Simulation and laboratory experimental tests of a line to shield medium voltage power line communication system
2011
A complete model of a power-line communication (PLC) system on a medium-voltage (MV) network in the case of a line-shield configuration is presented in this paper. An MV cable model in a line-shield configuration is considered together with the power transformers, the signal coupling networks, and the receiving and transmitting line coupling interface of a ST7540 FSK power-line transceiver. Simulations of the complete model of the system under consideration have been carried out for different line lengths, with and without power transformers and derivation branches. The model is validated by experimental tests performed in the laboratory. The measured results confirm the reliability of the …