Development of a low cost digital energy meter

This paper presents a versatile low cost equipment that allows simultaneous display of usually required measurements in electric circuits, like true RMS (Root Mean Square) values of mains voltage and current, line frequency, power factor, active, reactive and apparent power, and energy. The equipment is based on a microcontroller that interfaces current and voltage transducers through 16 bits sigma-delta ADCs (Analog to Digital Converters). The microcontroller controls the periodic acquisition of the measured signal waveforms, makes the respective calculations and presents the results on an alphanumeric display. The equipment also provides a serial port that enables the communication with other devices allowing the interface through a SCADA (Supervisory Control and Data Acquisition) system

Development of a monitoring system for electrical energy consumption and power quality analysis

This paper presents the development of a monitoring system for electrical energy consumption and power quality analysis, also known as power quality analyser (PQA). The internal architecture of the developed monitoring system is described in detail along the paper, highlighting the signal conditioning circuit and analogue to digital conversion (ADC) stage, the advanced RISC machine (ARM) processor, and the digital signal processor (DSP), which are used, respectively, for data acquisition, data communication and power quality calculations. This paper also describes the software developed for a Raspberry Pi, which receives the processed information from the ARM processor and presents it in real-time using a touch screen user-friendly interface. Among all the available features of the developed system, the paper presents the most relevant experimental results obtained with linear and nonlinear loads, showing the main functionalities of the different menus available in the developed user interface, mainly the menus “Scope”, “Harmonics” and “Data”.This work is supported by FCT with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.info:eu-repo/semantics/publishedVersio

Condicionadores ativos de potência para mitigação de problemas de qualidade de energia elétrica em instalações industriais

Os condicionadores ativos são equipamentos baseados em eletrónica de potência que permitem mitigar de forma dinâmica diversos problemas nas tensões e nas correntes do sistema elétrico, contribuindo efetivamente para a melhoria da produtividade das indústrias, reduzindo os prejuízos provocados pelos problemas de Qualidade de Energia Elétrica.Fundação para a Ciência e a Tecnologia (FCT

Single-phase series active conditioner for the compensation of voltage harmonics, sags, swell and flicker

Simulation and experimental results shown on this paper describes the performance of a developed Single-Phase Series Active Conditioner that regulates the voltage being delivered to a load. This Custom Power device is a solution for power quality issues related with voltage amplitude variations, which are responsible for innumerous flaws in industrial processes which brings with it high financial losses. The Single-Phase Series Active Conditioner is a back-to-back converter, composed by two power converters sharing a common DC link. One of the converters is series connected to the electrical grid, whereas the other one is shunt connected. The first is used to compensate load voltage, and the second to regulate the DC link voltage. This paper shows the results obtained with the Series Active Conditioner in Sag, Swell and Flicker events, and also Voltage Harmonics compensation, in order to deliver to the load a sinusoidal voltage, at nominal amplitude.Fundação para a Ciência e Tecnologia (FCT

Analysis of the features of a UPQC to improve power quality in smart grids

An UPQC (Unified Power Quality Conditioner) is an equipment composed by two active conditioners operating in a combined way. One of the active conditioners is connected in series with the electrical power system, allowing the compensation of problems in the system voltages. The other active conditioner is connected in parallel with the electrical system, and allows the compensation of current harmonics, current unbalances and power factor. In three-phase four-wire systems the parallel connected active conditioner also compensates the zero sequence current components, eliminating the neutral wire current. The UPQC operates in an automatic way, adjusting itself dynamically to the variations of the load and of the electrical system, keeping high levels of power quality in the voltages delivered to the load. At the same time, it only consumes from the electrical system the active power necessary to the load operation, in a balanced way through the three phases, and with sinusoidal currents. The compensation capabilities of the UPQC can be very useful to ensure high levels of power quality in the future Smart Grids, which are not characterized as a single technology or device, but rather as a vision of a distributed electrical system, supported by reference technologies, as Power Electronics Devices, Renewable Energy Resources, Energy Storage Systems (ESS), Advanced Metering Infrastructures (AMI), and Information and Communication Technologies (ICT).This work is financed by FEDER Funds, through the Operational Program for Competitiveness Factors – COMPETE, and by National Funds through the Foundation for Science and Technology of Portugal, under projects: PTDC/EEAEEL/104569/2008 and FCOMP-01-0124-FEDER-022674.info:eu-repo/semantics/publishedVersio

Unified architecture of single-phase active power filter with battery interface for UPS operation

This paper presents a shunt active power filter with battery interface for uninterruptible power supply (UPS) operation. The proposed unified architecture is composed by a single-phase ac-dc converter from the power grid side and by a bidirectional isolated dc-dc converter to interface the batteries, allowing the operation in three distinct modes: (1) Shunt active power filter; (2) Off-line UPS to supply a set of priority loads during power outages; (3) Energy storage system to support the power grid. The proposed architecture and the developed control algorithms were validated with a reduced-scale laboratorial prototype in all the three different operation modes. The presented experimental results highlight the benefits of the proposed architecture.Fundação para a Ciência e Tecnologia (FCT)info:eu-repo/semantics/publishedVersio

Development of an Internet of things system for smart home HVAC monitoring and control

This paper presents the development and test of an Internet of Things (IoT) system applied to the monitoring and control of an HVAC (Heating, Ventilation and Air Conditioning) system that includes parameters such as temperature, humidity, air quality, human presence and smoke detection. For this purpose, a hybrid wireless network combining Bluetooth Low Energy (BLE) and IEEE 802.11/Wi-Fi was implemented inside a house. An online database for the synchronization of the HVAC data, which was developed using the Amazon Web Services (AWS) cloud platform, allows the user to access the data and control the system parameters through the Internet using an Android mobile app. A smart temperature control system was also developed in the BLE/Wi-Fi gateway to keep the room temperature inside a user-defined range. The functionalities and performance of the proposed system were both validated through experimental tests.This work is supported by FCT with the reference project UID/EEA/04436/2019

Operation modes for the electric vehicle in smart grids and smart homes: present and proposed modes

This paper presents the main operation modes for an electric vehicle (EV) battery charger framed in smart grids and smart homes, i.e., are discussed the present-day and are proposed new operation modes that can represent an asset towards EV adoption. Besides the well-known grid to vehicle (G2V) and vehicle to grid (V2G), this paper proposes two new operation modes: Home-to-vehicle (H2V), where the EV battery charger current is controlled according to the current consumption of the electrical appliances of the home (this operation mode is combined with the G2V and V2G); Vehicle-for-grid (V4G), where the EV battery charger is used for compensating current harmonics or reactive power, simultaneously with the G2V and V2G operation modes. The vehicle-to-home (V2H) operation mode, where the EV can operate as a power source in isolated systems or as an off-line uninterruptible power supply to feed priority appliances of the home during power outages of the electrical grid is presented in this paper framed with the other operation modes. These five operation modes were validated through experimental results using a developed 3.6 kW bidirectional EV battery charger prototype, which was specially designed for these operation modes. The paper describes the developed EV battery charger prototype, detailing the power theory and the voltage and current control strategies used in the control system. The paper presents experimental results for the various operation modes, both in steady-state and during transients

Field results on developed three-phase four-wire shunt active power filters

Abstract-This paper presents three-phase four-wire Shunt Active Power Filters with ability to compensate current harmonics, power factor, and current unbalance. The power stage of the Active Power Filters is based on a two-level four-leg inverter. The switching technique is based on an optimized periodic sampling strategy, and the digital controller uses the Theory of Instantaneous Reactive Power (p-q Theory) expanded for three- phase four-wire systems. The presented Active Power Filters were successfully demonstrated in four different facilities. The presented experimental results show the performance of the Active Power Filters in operation with very different load profiles

Improved vehicle-for-grid (iV4G) mode: novel operation mode for EVs battery chargers in smart grids

The experimental validation of a novel operation mode for electric vehicles (EVs) to support the grid power quality is presented. The proposed operation mode, denominated improved vehicle-for-grid (iV4G), is directly associated with the EVs operation aiming the compensation of power quality problems associated with current harmonic distortion and reactive power, improving the total power factor of the electrical installation. Simultaneously with the proposed iV4G, where the EV injects current harmonics and provides reactive power, the EV can exchange active power with the grid (grid-to-vehicle, G2V, to charge the batteries or vehicle-to-grid, V2G, to deliver energy back to the power grid). In this paper, the proposed iV4G operation mode is experimentally validated with a developed EV battery charger prototype connected to an electrical installation of 230 V, 16 A, 50 Hz. The control strategies of the iV4G operation mode and the used prototype are described in detail along the paper. The achieved results confirm the feasibility and good performance of the proposed iV4G operation mode, working alone, and also when associated with the G2V and V2G operating modes.This work has been supported by FCT project 0302836 NORTE-01-0145-FEDER-030283. This work is also part of the COMPETE: POCI-01-0145-FEDER-007043 and FCT within the Project Scope: UID/CEC/00319/2013. This work isfinanced by the ERDF–European RegionalDevelopment Fund through the Operational Programme forCompetitiveness and Internationalisation–COMPETE 2020Programme, and by National Funds through the Portuguese fundingagency, FCT, within project SAICTPAC/0004/2015–POCI–01–0145–FEDER–016434