José Batista

Development of an Electrical Power Quality Monitor based on a PC

This paper describes an electric power quality monitor developed at the University of Minho. The hardware of the monitor is constituted by four current sensors based on Rogowski effect, four voltage sensors based on Hall effect, a signal conditioning board and a computer. The software of the monitor consists of several applications, and it is based on LabVIEW. The developed applications allow the equipment to function as a digital scope, analyze harmonic content, detect and record disturbances in the voltage (wave shapes, sags, swells, and interruptions), measure energy, power, unbalances, power factor, register and visualize strip charts, register a great number of data in the hard drive and generate reports. This article also depicts an electrical power quality monitor integrated into active power filters developed at the University of Minho.

Electric power quality monitoring results in different facilities

This paper presents results of electric power quality monitoring studies performed in different industries and in universities. The monitoring was made with an electric power quality monitor developed at the University of Minho. The studies were performed in different installations: textile industries, a pharmaceutical industry, a hospital and two universities. Therefore, the results showed in this paper were obtained in different electrical installations. It is important to emphasize that, the results here presented are not intended to establish profiles for each type of electrical installation. The aim is rather to show several electric power problems that occur in these types of facilities, and also to present the functionalities of the electric power quality monitor developed at the University of Minho, working out of laboratory, in real electrical installations.

Low-cost I-V tracer for photovoltaic modules and strings

This paper presents new developments of a robust and low-cost instrument - less than 600 € - for monitoring and processing I-V and P-V characteristics of photovoltaic (PV) modules and high voltage strings. The characteristics can be traced on an oscilloscope or using a developed a LabVIEW application. It is a simple instrument because only fundamental electronic circuits are used. The equipment consists of a flexible configuration, developed from a previous work, based on a fast varying load based on a power MOSFET. The MOSFET was controlled by means of suitable gate-source voltage control signal in order to improve the tracing of I-V and P-V characteristics on an oscilloscope. The contribution of this work includes new developments of a previous I-V tracer in order to be use with high voltage strings and a low-cost DAQ monitoring system based on two applications developed in LabVIEW - one for PV modules and the other for PV strings. On the other hand, the robustness for high voltage strings was strongly improved in view of field tests for fault diagnosis analysis. Experimental results obtained with the new instrument are presented with modules and different strings available with voltages up to 1000 volt.

A practical approach for grid-connected pico-hydro systems using conventional photovoltaic inverters

Pico-hydro power generation has a considerable untapped potential, able to contribute to the increased energy demand whilst ensuring a low environmental impact. The integration of these systems into microgrids is an emerging solution for the electrification of remote regions and also for self-sustainable power systems. The integration of cheap and wide spread technologies to interface small capacity hydro power systems with the grid has become essential in order to enable the exploitation of small rivers and shallows reservoirs resources among many other applications such as in water supply systems. This paper presents a design procedure to integrate pico-hydro generators into the grid using conventional and widespread photovoltaic inverters.

Bidirectional vehicle-to-grid interface under a microgrid project

In the emergent deployment of the smart grids, storage systems play an important role into assets utilization optimization, providing backup power and peak-shaving. This concept becomes more critical in the context of microgrids with a high penetration of renewable energy resources. Plug-in electric vehicles provide an enormous distributed storage capability, which favours the technical and economical exploitation of such systems. This paper presents a comprehensive implementation and control of a bidirectional power converter for vehicle-to-grid integration, based on a bidirectional DC/DC converter followed by a full bridge DC/AC converter. The evaluation of the adopted topology and its control is performed through simulation and experimental validation.

Sistema Digital de Bajo Coste para la Monitorización de la Calidad de Energía Eléctrica

This paper describes the development of a low-cost digital system used for power quality monitoring. The system uses voltage and current Hall sensors, a standard data acquisition board, and has its processing system based on LabVIEW™, running on a regular Personal Computer. Several parameters related to power quality can be analyzed through 4 different applications: “Scope and THD”, “Events PQ”, “Classical Values” and “p-q Theory”. The acquired information can be visualized in tables and/or in charts. It is also possible to generate reports in HTML format. In this format, the reports can be sent directly to a printer, can be embedded in other software applications, or can be accessed through Internet, using a web browser.

Compatibility analysis of grid-connected pico-hydro systems using conventional photovoltaic inverters

Small scale hydropower has a considerable untapped potential, able to contribute to the increased energy demand. The integration of these systems into microgrids is an emerging solution for the electrification of remote areas and for self-sustainable power systems. This paper is devoted to the design optimization of grid-connected pico-hydro systems using conventional photovoltaic inverters, providing cost effective solutions able to explore a large amount of feasible sites. Experimental tests of the proposed innovative topology with two inverters and selected generators were performed, evaluating the performance in steady state and dynamic conditions, corroborate the proposed design procedure.