Search results for "Voltage"
showing 10 items of 934 documents
An Adaptive Robust Predictive Current Control for Three-Phase Grid-Connected Inverters
2011
This paper presents an adaptive robust predictive current control (RPCC) for grid-connected three-phase inverters that exhibit zero steady-state current error. The error correction is achieved by means of an adaptive strategy that works in parallel with the deadbeat algorithm, therefore preserving the typical fast response of the predictive law. The resulting control adapts to any particular L or LCL filter by estimation of the resistive part of the filter. As a variety of the RPCC class of control, it offers the best tradeoff between robustness and speed. © 2009 IEEE.
A bottom-up approach for the evaluation of the flexible quota of aggregated loads
2015
The paper presents a bottom-up approach for building the aggregated load profile of numerous passive/active users connected to the low voltage electrical system. The approach is based on the Monte Carlo method and on the knowledge of the single electric and thermal loads, generators and thermal and geometrical characteristics of the building of the single end-user. The method proposed is able to differentiate the quota of flexible and not flexible aggregate load.
A Low-Power Fully-Mosfet Voltage Reference Generator for 90 nm CMOS Technology
2006
An integrated voltage reference generator, designed for being incorporated in standard 90-nm CMOS technology flash memories, is described in this paper. A fully MOSFET based approach, using also subthreshold operated devices, has been adopted in order to achieve low-voltage and low-power requirements and to overcome the difficulties of conventional band-gap reference circuits. The proposed circuit, based on current signals, internally generates two currents with opposite dependence on temperature. The two currents are added, thus canceling almost completely temperature dependence, and then linearly converted into the output voltage. For a temperature variation between -20degC and 90degC, th…
A simplified approach for load flow analysis in MV smart grids based on LV power measurements
2017
This paper presents a simplified approach for load flow analysis in medium voltage (MV) distribution networks. It is a power summation Backward/Forward (B/F) algorithm, based on measurements of active and reactive powers at low voltage (LV) side of MV/LV distribution substations. The proposed solution allows achieving good accuracy, computational efficiency and fast convergence. In order to verify the algorithm performances, simulation studies are carried out in the case of a real test system, i.e. the distribution grid of Favignana Island (Mediterranean Sea, Italy). The compatibility between simulations results and power measurements at the MV bus bars of the generating substation shows th…
A mathematical approach for studying interconnected earthing systems inside MV networks
2007
PurposeThe purpose of this paper is to define a new methodology for studying interconnected earthing system inside unearthed medium voltage (MV) networks.Design/methodology/approachThe developed methodology is based on the division of the MV network into simpler sub‐systems and its resolution using a multiport approach.FindingsThe methodology has been applied to various situations giving precious information on the behaviour of the interconnected earthing systems. The comparison between the results of the simulations and measurements done on a really existing network has shown that the methodology is able to provide accurate results.Research limitations/implicationsSome factors can influenc…
Simple equipment to measure biomechanical quantities of muscles and organs which includes a polarity-programmable peak detector
1982
Biomechanical measurements of muscles and organs require appropriate measuring equipment. As far as the static properties are concerned, the excursion of the bender bar of stress should be without force. The bender bar of force, however, ideally should not elongate under load. Because natural frequency is the most important boundary condition, the bender bar should be developed with this in mind. The developed bars imposed an insignificant preload to the muscle or to the organ. The small changes in resistance occurring in the resistance strain gauges affixed to the bars require the use of a highly stable amplifier. A new amplifier was accordingly developed based on the principle of an instr…
Proof of Concept of an Irradiance Estimation System for Reconfigurable Photovoltaic Arrays
2015
In order to reduce the mismatch effect caused by non-uniform shadows in PV arrays, reconfigurable interconnections approaches have been recently proposed in the literature. These systems usually require the knowledge of the solar radiation affecting every solar module. The aim of this work is to evaluate the effectiveness of three irradiance estimation approaches in order to define which can be well suited for reconfigurable PV arrays. It is presented a real-time solar irradiance estimation device (IrradEst), implementing the three different estimation methods. The proposed system is based on mathematical models of PV modules enabling to estimate irradiation values by sensing a combination …
Experimental validation of a general model for three phase inverters operating in healthy and faulty modes
2012
The paper presents the experimental verification of a general mathematical model of Voltage Source Inverters (VSI) able to simulate fault conditions and which is also useful for the simulation of fault-tolerant systems for different applications. In general, in the past, the problem of faulty inverters modeling has been addressed specifically by considering faults on the different phases as separate cases. Furthermore, traditional models include only the faulty mode and not the healthy mode, so resulting then not able to predict transient phenomena. The model hereafter presented overcomes this drawback. It was formulated by introducing the concept of “healthy leg binary variables”. Such var…
Current-Sensing Technique for Current-Mode Controlled Voltage Regulator Modules
2008
This paper introduces an innovative current-sense technique for voltage regulator modules (VRMs). The proposed method is applied to a multiphase buck converter although the converter topology does not affect the accuracy or effectiveness of the proposed technique. A RC network is parallel connected with the buck converter low-side MOSFET and the voltage signal across the sense capacitor reconstructs the inductor current waveform. The RC technique benefits from all the advantages of the most popular current-sensing technique, the inductor DC resistance current-sense method, cutting off its main disadvantage. The sense network design is oriented to obtain high immunity to noise and a great dy…
Applications of the Fault Decoupling Device to Improve the Operation of LV Distribution Networks
2008
The aim of this paper is to present the operating principle of a new resonant device, called the fault decoupling device (FDD), able to improve power quality in electrical distribution systems. In low-voltage networks, this device can be employed in order to mitigate voltage dips due to faults or large induction motor startup. Moreover, in the presence of distributed-generation (DG) units, the FDD allows one to obtain various benefits such as a reduction of the fault current in each node of the network and an increase in the voltage at the DG unit node. In order to show the performances of the FDD, analytical studies and computer simulations were carried out which took into account various …