Fault Detection and Identification for Maintenance Management

Photovoltaic solar energy is increasing the energy production due to the technological advances, together to the initial investment reduction. Solar farms are being installed with larger production capacity, improving the technical challenge for developing correct and efficient maintenance management. The photovoltaic maintenance management requires to increase the reliability and reduce the operating costs. The photovoltaic panels inspection with unmanned aerial vehicles is an efficient condition monitoring technique, analyzing large areas and obtaining accurate thermographic images. Due to the large amount of data, it is necessary the use of image processing algorithms for automatic identification of faults. Despite these advances, it is required the identification of the type and the importance of the fault. This information will be used by the plant operators for developing efficient maintenance management plans. The novelty developed in this work is a robust decision system for photovoltaic maintenance management, based on the combination of image processing for fault detection and statistic techniques. The first phase of the methodology is the extraction of interest areas or possible faults with neural networks trained for this purpose. The second phase develops the statistical analysis of the radiometric data of the area detected as possible fault with neural network. The radiometry data of these areas will be analyzed with statistic models with the aim of detecting patterns for detect identification and quantification. A real case study of a solar plant is presented, and the results obtained with this methodology provide the positioning and importance of each defect, probing the strength of the method

Los rótulos de las librerías e imprentas en Barcelona: la publicidad exterior de los establecimientos (1780-1839)

Los libreros e impresores de Barcelona presentaron al ayuntamiento solicitudes de reforma de los rótulos de publicidad exterior de sus negocios, al menos, desde 1771. También solicitaban poder instalar mecanismos móviles como tableros, tablillas y tablones, así como mostradores con la finalidad de mostrar su mercancía en la vía pública. Estos medios de comunicación pública de libros y novedades editoriales reflejan una renovación de la presencia de la publicidad exterior de los establecimientos

Condition Monitoring System for Solar Power Plants with Radiometric and Thermographic Sensors Embedded in Unmanned Aerial Vehicles

The photovoltaic solar energy industry is expanding, and there is therefore a need to increase and improve its maintainability, operating costs, availability, reliability, safety, life cycle, etc. The aim of this article is to design, develop and check a new condition monitoring system to detect dust in solar photovoltaic panels. The condition monitoring system uses a radiometric sensor connected to an Arduino platform. This novel approach is based on emissivity analysis produced over a surface and characterized with a low emissivity value when dust appears. A thermographic camera is also employed to validate the results provided by the radiometric sensor. The system is designed to be embedded in an unmanned aerial vehicle. Radiometric data is sent and analysed, Internet of Things is employed, and thermograms are stored for further processing. Several scenarios with a real solar panel are used in the experiments, in which the angles and distances of the sensors and surface conditions are studied. An analysis of the radiometric sensor provides accuracy results, and the presence of dust is identified in all scenarios

Design and analysis of ripple-based controls based on the discrete modeling and Floquet theory

Ripple-based controls can strongly reduce the required output capacitance in PowerSoC converter thanks to a very fast dynamic response. Unfortunately, these controls are prone to sub-harmonic oscillations and several parameters affect the stability of these systems. This paper derives and validates a simulation-based modeling and stability analysis of a closed-loop V 2Ic control applied to a 5 MHz Buck converter using discrete modeling and Floquet theory to predict stability. This allows the derivation of sensitivity analysis to design robust systems. The work is extended to different V 2 architectures using the same methodology

Interaction effects of fermentation time and sourdough content on the size and acidity in bread

The use of sourdough to provide certain physical, organoleptic and nutritional properties to bread is one of the most used biotechnological processes in the production of cereal-based foods. Sourdough, yeast and fermentation time are elements that provide rising to the bread, in addition to aroma, flavour and nutritional properties. The time of fermentation of the dough before baking and the portion of sourdough added in the dough pieces are decisive on the acids formation by microbiological action, and thus, the properties of the bread. The physical aspect is also an important factor in the final product, and it can be widely affected according to the percentage of sourdough used and the fermentation time prior to baking. This is due to the variation in the rheological properties of the dough and possibly to the competition existing in the microbiota development. In this work, the interaction effects of fermentation time and sourdough content on the size and acidity in bread are assessed. For this purpose, bread samples were prepared with a fixed amount of yeast and 0, 20 and 50% sourdough portions. Afterwards, they were allowed to ferment periods of 0, 60, 120, 180, 240, 300 and 360 minutes before being baked. The results obtained are reported in the present work.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Multiphase transformer-coupled converter: two different strategies for energy conversion

The operation of a multiphase topology, ideally, without energy storage presents the advantage of achieving very high efficiency over a wide load range as well as a fast dynamic response. However, ideal no-energy storage operation also implies a limitation in the regulation capability of the topology, the output voltage can only take discrete values. These features (high efficiency and discrete regulation capability) of the proposed energy conversion strategy enable the topology as a candidate for `DC-DC transformer' applications. The advantages, drawbacks and the operating principle of this concept, implemented with a `closed chain' magnetic structure have been already presented. In this work, the minimum energy storage operation, is applied to two different magnetic structures. These magnetic structures are called `closed chain' and `pyramidal' the main advantage of the `pyramidal' coupling structure is to improve the size of the converter without increasing the operating frequency. Both magnetic structures are analyzed, compared and experimentally implemented

Multiphase Current Controlled Buck Converter with energy recycling Output Impedance Correction Circuit (OICC)

This work is related to the output impedance improvement of a Multiphase Buck converter with Peak Current Mode Control (PCMC) by means of introducing an additional power path that virtually increases the output capacitance during transients. Various solutions that can be employed to improve the dynamic behavior of the converter system exist, but nearly all solutions are developed for a Single Phase Buck converter with Voltage Mode Control (VMC), while in the VRM applications, due to the high currents, the system is usually implemented as a Multiphase Buck Converter with Current Mode Control. The Output Impedance Correction Circuit (OICC) is used to inject or extract a current n-1 times larger than the output capacitor current, thus virtually increasing n times the value of the output capacitance during the transients. Furthermore, this work extends the OICC concept to a Multiphase Buck Converter system while comparing proposed solution with the system that has n times bigger output capacitor. In addition, the OICC is implemented as a Synchronous Buck Converter with PCMC, thus reducing its influence on the system efficienc

An overview of fast DC-DC converters for envelope amplifier in RF transmitters

In the last years, RF power amplifiers are taking advantage of the switched dc-dc converters to use them in several architectures that may improve the efficiency of the amplifier, keeping a good linearity. The use of linearization techniques such as Envelope Elimination and Restoration (EER) and Envelope Tracking (ET) requires a very fast dc-dc power converter to provide variable voltage supply to the power amplifier but theoretically the efficiency can be much higher than using the classical amplifiers belonging to classes A, B or AB. The purpose of this paper is to analyze the state of the art of the power converters used as envelope amplifiers in this application where a fast output voltage variation is required. The power topologies will be explored and several important parameters such as efficiency, bandwidth and output voltage range will be discussed

Trade-off between Energy Savings and Execution Time Applying DVS to a Microprocessor

DVS (Dynamic Voltage Scaling) is a technique used for reducing the power consumption of microprocessors. The power consumed by these circuits has a main component (dynamic power) that is proportional to the square of the supply voltage. Additionally, for every supply voltage, there is a maximum value of the clock frequency. The advantage of using DVS is that the supply voltage (and hence clock frequency) can be adjusted depending on the specific needs during execution. The DVS concept has been used in some commercial products like Transmeta’s Crusoe [1], Intel Speed Step [2], AMD K6 [3], Hitachi SH4 [4], etc. The DVS algorithm proposed in this work is based on the trade-off between the application’s execution time and the energy consumed by the microprocessor. Indirectly, by controlling the execution time the consumed energy is controlled as well. Longer execution time provides less energy demanded by the CPU. The algorithm has been implemented on a platform with an Intel XScale PXA255 microprocessor and the energy saving has been calculated directly measuring currents and voltages on the platform. Using this technique it is possible to achieve up to 50% of power savings, with 50% longer execution time

A DVS system based on the trade-off between energy savings and execution time

DVS (Dynamic Voltage Scaling) is a technique used for reducing the power consumption of digital circuits. The power consumed by these circuits has a main component (dynamic power) that is proportional to the square of the supply voltage. Additionally, for every supply voltage, there is a maximum value of the clock frequency. The advantage of using DVS is that the supply voltage (and hence clock frequency) can be adjusted depending on the specific needs during execution. The DVS concept has been used in some commercial products like Transmeta’s Crusoe [1], Intel Speed Step [2], AMD K6 [3], Hitachi SH4 [4], etc. This paper presents results obtained by using a DVS algorithm based on the workload estimation and trade-off between the execution time and power savings. It is discussed about influence of the power supply’s slew rate, algorithms influence on the system performance and problems to estimate the processors workload. The DVS system is realized on Intel’s PXA255 platform and energy savings have been calculated by measuring directly voltages and currents on the platform