Search results for "Generation"
showing 10 items of 3050 documents
A circuit model of a 5kW fuel cell
2013
In the last few years, industrial research has been focused on renewable energy sources. Owing to combined heat-power generation option, fuel cells have attracted much interest for a wide variety of research areas. Household appliances are still the most promising applications. Fuel cell modeling is still a critical topic to focus on, affecting each stage of power system design. This paper describes an empirical method to model a proton exchange membrane fuel cell. The modeling approach is applied to a 5kW Nuvera PowerFlow fuel cell. A circuit model is proposed for further applications. PSPICE implementation is described and the parameters tuning procedure is discussed. Simulation and exper…
Bearing fault detection for drivetrains using adaptive filters based wavelet transform
2017
Predicting a localized defect on a rolling bearing during the degradation process before a complete failure is crucial to prevent system failures, unscheduled downtimes and substantial loss of productivity. During this process, impulses associated with the fault are weak, nonstationary or time-frequency varying, and contaminated by noises, which render the problem of extracting these impulses very difficult. This work investigates the effectiveness of common signal processing techniques on predicting incipient faults, e.g. Fast Fourier transform, Short-Time Fourier transform, Wavelet transform. It was found that an adaptive filter is required to enhance and reconstruct the signals during th…
A New Device for the Control and the Connection to the Grid of Combined RES-based Generators and Electric Storage Systems
2013
In this paper a new device for the control and the connection to the supply utility grid of combined RES-based generators and electric storage systems is presented. The device is a bidirectional converter that can be controlled so as to facilitate the interface between the low voltage grid and photovoltaic or wind generators combined with batteries, contemporary addressing the requirements of the reference technical standards for users connection and providing different ancillary services. In the paper the functioning of the device and its circuit diagram are described, the single parts are shown and the potentiality of its control system are commented. © 2013 IEEE.
A novel fuel cell-based power system modeling approach
2013
Nowadays, fuel cells are the most promising source of energy for stationary applications. Unfortunately, the power density of fuel cells is not adequate for modern applications. A fuel cell - based hybrid power supply is required. The fuel cell is coupled with a high-energy density power source to improve performances of the composite power source. A power management stage is introduced between the two basic sources to control the power flow path from the fuel cell to the auxiliary source and the load. In order to avoid effects of a limited power density of the fuel cell on the whole power supply, sophisticated power management algorithms are implemented. Accurate modeling is required to te…
A description model for regeneration through urban tourism in rural towns with underused historic real estate
2016
Il presente contributo propone un modello di descrizione (description model) che trova applicazione in una situazione reale di aiuto alla decisione posto dall'urbanista per lo sviluppo turistico delle città rurali nelle zone dell'entroterra siciliano. Il problema decisionale riguarda la città di Cianciana (AG), che negli ultimi anni si è resa protagonista di un particolare fenomeno di turismo internazionale. In particolare, proponiamo un quadro valutativo multicriteriale per la riqualificazione fisica ed economica del centro storico della città attraverso lo sviluppo del turismo. Il modello presentato, relativo a un problema decisionale di tipo descrittivo, è orientato a supportare i deciso…
Impact of integrating photovoltaic based DG on distribution network harmonics
2017
The process of integrating various distributed generation (DG) technologies in power system networks is increasing rapidly in the recent years. One major concern about the integration of DGs is their impact on network harmonics. The aim of this paper is to investigate the effects caused by the integration of photovoltaic DG in distribution networks on system harmonics. The penetration level, number of DG units, and their location are used as parameters in order to verify the effects of DG on system harmonics. Moreover, a study of single and double tuned filters is conducted as harmonics mitigation techniques. Detailed simulations using Matlab/Simulink are inserted in order to explain and ve…
Impedance estimation of FEA's grid in fiji islands by V-I measurement by using the synchronous reference frame-PLL
2017
In recent years there has been a significant increase in distributed renewable energy generation feeding into the grid, with resulting detriment of the stability of the network, since present networks have not been designed for this purpose. To feed-in these renewable energy sources with minimum impact, it is essential to know a few grid parameters (voltage, current, grid impedance) at the point in which power supply is convenient. For this purpose in this paper an algorithm is proposed to obtain the estimated network impedance. This algorithm operates in time domain by a synchronous reference coordinate transformation, it requires only the measurement of the phase voltage with no-load and …
Hybrid passive and communications-based methods for islanding detection in medium and low voltage smart grids
2013
Islanding condition takes place when a distributed generator (DG) continues to power a part of the grid even if power from electric utility is no longer present. Adverse effects of islanding are power quality deterioration, grid-protection interference, equipment damage, and personnel safety hazards. For these reasons, DG systems must detect an islanding condition and immediately disconnect from the grid (anti-islanding protection). This paper proposes an hybrid solution, for both low voltage (LV) and medium voltage (MV) applications, which makes use of passive and communication-based methods for islanding detection. Among the existing communication technologies, the study is focused on pow…
Control of solid-state fault current limiter for DG-integrated distribution systems
2017
Fault current limier (FCL) is a device that limits the system current under fault conditions without disconnecting the system and affecting the power system protection components such as circuit breakers. Many types of FCLs have been proposed to limit the magnitude of the fault current. Solid-state fault current limiters (SSFCLs) can limit the peak value of the fault current by applying several methods, such as controlling the system impedance or controlling the voltage that appears across the fault. In this paper, a new control scheme for the SSFCL circuit is presented. The control method is based on controlling the duty cycle of solid state switches to control the rms value of the system …
Flexible power converters for the fault tolerant operation of Micro-Grids
2010
The progressive penetration level of Distributed Generation (DG) is destined to cause deep changes in the existing distribution networks no longer considered as passive terminations of the whole electrical system. A possible solution is the realization of small networks, namely the Micro-Grids, reproducing in themselves the structure of the main production and distribution of the electrical energy system. In order to gain an adequate reliability level of the microgrids the individuation and the management of the faults with the goal of maintaining the micro-grid operation (fault tolerant operation) is quite important. In the present paper flexible power converters and a companion control al…