Search results for "Forming"
showing 10 items of 1719 documents
Planning Augmented Cities in the Neoanthropocene
2020
To improve the effects of the connecting “augmented urbanism”, I have set up ten keywords able to reset spatial planning for the Augmented City in the face of the 21st century challenges. The Augmented City’s practices grow with exponential progression doubling its components, connections and impacts seen in the last years, to one incredible and disruptive acceleration. We are surrounded by thousands of practices in the spread of sensors and intelligent devices, in collaborative design and return of urban manufacturing, in explosion of creativity and increase of resilience, and several experiments in recycling of everything, fluidisation and networking of cities, and adoption of incremental…
On the sustainability evaluation in sheet metal forming processes
2011
In sheet metal forming processes there is still a lack of knowledge in the field of environmental sustainability mainly due to the need of a proper modeling of issues and factors to be taken into account. Such topic is, nowadays, a urgent and remarkable issue in manufacturing and the main concerns are related to more efficient use of materials and energy. What is more, the estimation of environmental burdens of forming technologies is very complex to be accomplished since it is essentially process-dependent. This means that when comparing, for instance, a traditional forming process with an innovative one, there are some peculiar aspects to be considered; actually, processes can be rather d…
Dynamic Control of Static Converters for the Transition from Grid-on to Grid-off Operation of AC/DC Microgrids
2022
In this paper, specific control logics defined for generators, controllable loads and electric energy storage systems are illustrated in order to improve the reliability of AC/DC hybrid microgrids in their grid-off operation following failure events such as short-circuits, line breaks, sudden disconnections of generating units or loads, etc. After defining specific control schemes, these were modelled in a digital environment and finally tested with dynamic simulations. Finally, the paper highlights the role of virtual synchronous machine control for the self-healing capacity of islanded hybrid microgrids.
Frequency Dynamics in Fully Non-Synchronous Electrical Grids: A Case Study of an Existing Island
2022
The operation of a power system with 100% converter-interfaced generation poses several questions and challenges regarding various aspects of the design and the control of the system. Existing literature on the integration of renewable energy sources in isolated systems mainly focuses on energy aspects or steady-state issues, and only a few studies examine the dynamic issues of autonomous networks operated with fully non-synchronous generation. A lack of research can be found in particular in the determination of the required amount of grid-forming power, the selection of the number and rated power of the units which should implement the grid-forming controls, and the relative locations of …
Synchronizing Interactions Between Different Types of Grid-Forming Converters in Smart Grids
2022
The work investigates the transient synchronizing interactions between different types of grid-forming controls. Two well-known grid-forming schemes are implemented and considered for analysis: a droop-based control and a swing-based control. The two controls are examined for a temporary loss of synchronism. The analysis is performed considering two different conditions for the grid interconnecting the converters: a resistive-inductive grid and a mainly inductive grid. The first case corresponds to actual conditions in low and medium voltage applications. The second case is realized with the implementation of a virtual reactance in the grid-forming control scheme. The analysis of the result…
Grid-forming converters. A critical review of pilot projects and demonstrators
2022
Grid-forming control can be a useful solution for all dynamic issues in weak grids and for providing ancillary services. It represents the new frontier in modern power electronics, responding to the needs of power systems more and more rich in renewables and, for this reason, with lower inertia. Today, the research on grid-forming is mainly oriented to propose new and more effective control schemes and to evaluate their performances with simulation tools, but few works in the literature focus on the results of on-field experimentation. Therefore, this paper aims to provide a comprehensive review of grid-forming pilot projects and demonstrators developed worldwide. The work describes the mai…
AN ACCURATE MODEL FOR STEADY-STATE AND DYNAMIC ANALYSIS OF THE SICILIAN NETWORK WITH HVDC INTERCONNECTIONS
2021
Sicily is one of the first Italian regions for installed power from renewable energy plants, especially photovoltaic and wind plants, and a crucial point for the Mediterranean energy hub. Its role as nexus between the European and the African Continents is becoming more and more significant due to the realization in a short time of the so called Tyrrhenian link and the High Voltage Direct Current (HVDC) connection with Tunisia. In this framework, the paper presents a model of the Sicily power generation and transmission system, including the Tyrrhenian link and two equivalent buses representing the Sardinian power network and the rest of the Continental Europe (CE) synchronous area, for both …
Fundamental Analysis of Grid-Forming Converters Enhanced with Feedforward Controls
2022
The grid-forming control for power converters can be enhanced by proper feedforward terms included in the active power control loop. Two basic structures are identified, the feedforward angle and the feedforward frequency. The formal analysis of the transfer functions reveals a structural similarity. The two schemes exhibit however a fundamental difference in their transient capabilities. The grid-forming controls are characterized with the introduction of two specific factors, for the direct assessment of the inertia and the damping which can be provided by the grid-forming converter. The sensitivity analysis of the two feedforward schemes indicates that the enhancement of the transient pe…
A Comparison between RMS and EMT Grid-Forming Implementations in MATLAB/Simscape for Smart Grids Dynamics
2022
The article presents a comparison between phasor RMS and EMT models for grid-forming converters. The specific aspects related to the implementation in Simscape Electrical of MATLAB/Simulink are discussed for both RMS and EMT time-domains. The comparison between the different implementations is performed with the simulation of two widely studied grid-forming schemes, the virtual synchronous machine and the power-synchronization control. The simulation-based comparison examines transient phenomena with different characteristics and time scales, including frequency transients, phase jumps and short-circuit events. Specific indications regarding limitations and suitability of grid-forming model…
Grid-Forming Converters in Weak Grids – The Case of a Mediterranean Island
2019
The existing power network of a Mediterranean island is used as test bed for the study of grid-forming converter dynamics in weak grid conditions. The control scheme adopted for the converter falls in the category of the so called virtual synchronous machines (VSM). Particular attention is committed to the interaction between the converter controls and the synchronous machines dynamics. Time delays typically associated to measurements and filters are considered in the study, and included in the system model with a specific mathematical approach. Time-domain simulations show the occurrence of oscillatory instability in the system, with VSM and synchronous machines swinging against each other…