Milena F. Pinto

Smart modules for lighting system applications and power quality measurements

Smart lighting applications are designed to provide management and control of the whole interconnected system, ensuring reliability, cost saving and high efficiency. In this work is proposed a simple intelligent module to be connected in the street lighting system in order to simultaneously control and measure the lamps parameters. All the data transmission procedure was developed based on the mesh network topology. By taking advantage of the communication structure used for the smart lighting system and coupling sensors to the module, its possible to gather data regarding the power grid as well. Moreover, for experiments purposes, it was also developed a specific driver capable to communicate by DALI protocol in order to receive and send information from the smart module to the lamp. The results have proven the efficiency, flexibility and interoperability of the proposed smart device.

A fast dynamics and PWM-dimmable LED driver for accurate control of illumination in plants physiology experiments

This work presents an electronic system in order to provide a simplified and efficient alternative for plants physiology experiment as well as for its utilization in greenhouses. Initially, it is shown a brief description regarding the artificial lighting and plants cultivation interaction, aiming the interpretation about plants behavior in botanic studies and to help the oriented and commercial crops purposes. Based on some previous work, it is proposed an autonomous system comprised of a white LEDs lighting fixture. Moreover, this paper includes an experimental prototype in order to evaluate converter efficiency and radiometrie lamp behavior. Thus, the results have shown that the developed system is able to integrate flexibility, accurate control and relevant radiometric for some selected crops.

Least squares optimization of zero crossing technique for frequency estimation of power system grid distorted sinusoidal signals

Reliable frequency estimation is considered crucial for several industrial applications, such as power control, power system protection and monitoring. In certain applications is required an accurate and fast frequency estimations of the sinusoidal signals. Several algorithms are found in literature able to solve this task. However, their responses under low Signal to Noise Ratio (SNR) are not reliable. In this paper is proposed an optimization by least squares of the well-known zero-crossing technique in order to enhance performance under such condition. To validate the algorithm, it was performed some comparisons with other methods using different values of frequency. The presented technique has shown better results regarding the estimation error.

Variable window length applied to a modified Hanning filter for optimal amplitude estimation of power systems signals

Parameters estimation of electrical power system is relevant for monitoring, protection and control. Several methods are used to this purpose, such as Discrete Fourier Transform (DFT), Moving Average Filter (MAF), Hanning window, among others. However, some of these techniques require a number of samples within a complete number of cycles of the fundamental component in order to obtain better results. The oscillation of the systems frequency hinders the selection of a fixed window length. In this sense, in this paper is proposed a variable window length applied in a modified Hanning filter in order to optimally estimate the amplitude as well as eliminate harmonics and inter-harmonics of the power systems signals. The modified version of the Hanning filter proposed in this work enhances the magnitude response by altering the poles locations of the transfer function, achieving optimal removal of the first harmonic considering only one cycle of the signal which is unachievable by the conventional Hanning window, and the change of the window length according to the systems estimated frequency applied in this modified filter, allows for optimal removal of harmonics even when considering variable frequency.

Economic analysis of a controllable device with smart grid features applied to LED street lighting system

Almost all luminaires that are used in street lighting system does not have communication, control and management infrastructure. Moreover, the artificial lighting system is responsible for the consumption of approximately 30% of all electricity generated in the world. Within this context, the LED technology offers flexibility and high efficiency, being suitable to be connected with smart devices, allowing the usage of possible alternatives to reduce energy consumption and providing significant economic saving. This work aims to perform an economic analysis of a controllable device with smart grid features applied to LED street lighting system in order to evaluate the efficiency of its usage as well as possible benefits on public lighting system and monitoring of low voltage grid parameters. The results have shown low payback periods and a promising internal return rate when compared with other applications, such as saving accounts. The smart grid features on the controller allows simple integration with renewable sources and central management and controlling lighting system.

LED-based electronic system to support plant physiology experiments

This paper proposes an electronic system intended to provide a simplified and efficient alternative for plant physiology experiments, as well as to be used in greenhouse conventional processes. The text starts with a description regarding the interaction between artificial lighting and cultivation of vegetables, either for agricultural-oriented purposes or to help the interpretation of plants behavior in botanical studies. This first study helps to characterize the main radiometric quantities of interest, with a predominant orientation for growing vegetables when artificial lighting is used as a supplement or as a sole lighting source. Hence, based on some previous works, it is proposed a standalone system intended to drive a lighting fixture consisting of white power LEDs or mixed-color LED unities. Moreover, the paper also includes some preliminary radiometric experiments concerning a possible commercial LED, which is intended to be used in association with the proposed lighting fixture. The results should indicate if the LED brands are enough to excite a good photosynthetic response. Hence, the most relevant parameters are measured, such as the photosynthetic photon flux, luminous flux, lamp color rendering and color correlated temperature. It is expected that the developed prototype be able to present features that add flexibility, automation and radiometric relevance to some selected vegetable crops.

Power quality measurements embedded in smart lighting systems

Considering the three main infrastructure of the actual power system (generation, transmission and distribution), where the latter receives least attention towards the modernizing grid. However, in the new context of smart grid, the distribution network plays an important role and topics related to monitoring of the power quality parameters are of great relevance to achieve the so called smart distribution network, providing valuable and reliable information to be used in control and protection schemes and also representing an important asset which aids distribution utilities and consumers to diagnose and fix the systems problems besides enabling regulators with tools for measuring the quality of services supplied by utilities. In this way, the proposed work aims at the development of a modular and smart device to be attached in public lighting systems, enabling the control and management of the lamps parameters as well as to measure some power quality indicators from the distribution system and providing a communication infrastructure for the information exchange with a supervisory system.

Case-based reasoning approach applied to surveillance system using an autonomous unmanned aerial vehicle

The advanced use and the evolution of technologies regarding autonomous Unmanned Aerial Vehicle (UAV) have increased the availability of information and resources to perceive the environment, allowing its application in various activities, such as inspection and military. However, the intelligence level of these kind of systems needs to be improved in order to fit them in modern tasks. In this sense, this work proposes a high-level processing approach to be embedded in UAV system for understanding human activities in real environment. Additionally, the Case-Based Reasoning (CBR) methodology is also applied to allow the adaptation of the flight plan and the fully autonomous surveillance in limited areas. In order to enhance the solution, the proposed architecture is inspired in the biologic model of the human cognitive system and comprises low, middle and high levels to enable the perception of the environment as well as comprehension of the scene. The experiments have shown technical feasibility and effectiveness of the architecture. Moreover, the use of UAV has reduced the number of cameras and operators, being also capable to reach difficult areas.

Street lighting system for power quality monitoring and energy-efficient illumination control

This paper proposes a system for management, control and monitoring a group of LED luminaires of a street lighting infrastructure, enabling the measurement of certain parameters that are useful for a more proper and efficient operation of public lighting, while still monitoring the power quality of the electrical grid. These parameters include dimming level, power consumption, power factor, detection of pedestrians, malfunction in the luminaire and environmental conditions, such as solar irradiation, temperature and humidity. Two modules and a supervisory software compose the system. The first device is the smart module (SM), whose task is to measure the parameters stemming from the power grid as well as from the luminaire. The second is the control module (CM), which coordinates the data received from each smart module, store and subsequently send them to the supervisory system in a more suitable communication link. The supervisory system (SS) is responsible to save the information in a database, analyze and detect problems or even possible faults while sending commands to each CM. With the aim to evaluate the proposed system, it was performed experiments to demonstrate its operation as well as the power quality analysis capability. The results have shown energy efficiency potential due to the type of lamp used and the insertion of proposed system.

Adjustable window for amplitude estimation considering the time-varying frequency of power systems signals

The development of signal processing techniques that allows the estimation of parameters from the power system are crucial to keep the grid within a safe margin of operation. Some methods require a specific sampling rate in order to avoid asynchronous sampling, which may result in errors in estimation algorithms. Due to unbalances between demand and supply, the power signal is time-varying in nature, hindering the selection of an optimal fixed window length. In this work is proposed a technique in which the window length adapts to the actual value of estimated frequency, achieving better performance. The filter utilized to test the method was a moving average filter, but it can be expanded for other algorithms. Results have shown good performance when changing the filter coefficients according to frequency estimation.