José Manuel Andújar Márquez

A Methodology for Optimizing Stand-Alone PV-System Size Using Parallel-Connected DC/DC Converters

The installation of parallel-connected dc/dc converters allows energy and cost saving in photovoltaic (PV) systems. This paper develops a methodology with several algorithms to study the annual energy saving obtained with paralleled dc/dc converters in any world location. Moreover, this methodology allows one to select the minimum-cost size of a stand-alone PV system with dc/dc converter paralleling. For this purpose, a power-system sizing computer tool has been used, but its initial capabilities have been extended. The developed methodology allows for decision taking before investment is made.

A Converter for Bipolar DC Link Based on SEPIC-Cuk Combination

This letter describes a new application of single-ended primary converter (SEPIC) and Cuk converter for dc bipolar network. A dc-dc converter configuration based on a combination of both converters is proposed. In the resulting topology, the switching node is shared by the SEPIC and Cuk converter since they have the same instantaneous duty cycle. The main advantage of this topology is that synchronization of various switches is not required and control terminal is connected to ground which simplifies the design of the gate drive. On the other hand, this configuration allows the connection of renewable energy sources to microgrids (MG)-type bipolar dc link and to cover the current needs of new distributed generation units with efficient, economical, and easy way. To verify its performance, a prototype was designed. Experimental results show as this combination of two converter topologies with appropriated modulation schemes are adequate to use in dc MG.

A General and Formal Methodology to Design Stable Nonlinear Fuzzy Control Systems

The price to be paid for the great dynamic richness of nonlinear systems is the lack of a unitary theory that allows control-system design to be tacked in a way that is parallel or analogous to that of linear systems. We propose a general methodology that uses fuzzy logic to systematically and formally synthesize nonlinear control systems, which are stable by design. Although this methodology is based on Lyapunov theory, it avoids searching for Lyapunov functions. This allows the synthesis procedure to be systematic as well as formal and, especially, independent of heuristics. Some examples of nonlinear control are solved in this paper, thus allowing assessment of the proposed methodology.

Ground Thermal Diffusivity Calculation by Direct Soil Temperature Measurement. Application to very Low Enthalpy Geothermal Energy Systems

This paper presents a methodology and instrumentation system for the indirect measurement of the thermal diffusivity of a soil at a given depth from measuring its temperature at that depth. The development has been carried out considering its application to the design and sizing of very low enthalpy geothermal energy (VLEGE) systems, but it can has many other applications, for example in construction, agriculture or biology. The methodology is simple and inexpensive because it can take advantage of the prescriptive geotechnical drilling prior to the construction of a house or building, to take at the same time temperature measurements that will allow get the actual temperature and ground thermal diffusivity to the depth of interest. The methodology and developed system have been tested and used in the design of a VLEGE facility for a chalet with basement at the outskirts of Huelva (a city in the southwest of Spain). Experimental results validate the proposed approach.

Improving Skills and Perception in Robot Navigation by an Augmented Virtuality Assistance System

Successful navigation in a teleoperation scenario requires a good level of situational or environmental awareness. This paper presents the main features and capabilities of a new augmented virtuality-based system aimed at providing users with improved perception of the robot’s remote environment. With this purpose, a mixed-perspective exocentric display (ME3D), and a video centric display (VC2D) are compared. Both interfaces were implemented on a mobile robot and experiments were performed in a real working scenario. To assess this contribution, this works analyzes the teleoperation capability, performance, and human workload of users by means of NASA-TLX (Task Load Index). The results show that participants experienced a reduction in the driving workload and showed high degrees of acceptance for the proposed ME3D interface.

A New Metre for Cheap, Quick, Reliable and Simple Thermal Transmittance (U-Value) Measurements in Buildings

This paper deals with the thermal transmittance measurement focused on buildings and specifically in building energy retrofitting. Today, if many thermal transmittance measurements in a short time are needed, the current devices, based on the measurement of the heat flow through the wall, cannot carry out them, except if a great amount of devices are used at once along with intensive and tedious post-processing and analysis work. In this paper, from well-known physical laws, authors develop a methodology based on three temperatures measurements, which is implemented by a novel thermal transmittance metre. The paper shows its development step by step. As a result the developed device is modular, scalable, and fully wireless; it is capable of taking as many measurements at once as user needs. The developed system is compared working together on a same test to the currently used one based on heat flow. The results show that the developed metre allows carrying out thermal transmittance measurements in buildings in a cheap, quick, reliable and simple way.This paper deals with the thermal transmittance measurement focused on buildings and specifically in building energy retrofitting. Today, if many thermal transmittance measurements in a short time are needed, the current devices, based on the measurement of the heat flow through the wall, cannot carry out them, except if a great amount of devices are used at once along with intensive and tedious post-processing and analysis work. In this paper, from well-known physical laws, authors develop a methodology based on three temperatures measurements, which is implemented by a novel thermal transmittance metre. The paper shows its development step by step. As a result the developed device is modular, scalable, and fully wireless; it is capable of taking as many measurements at once as user needs. The developed system is compared working together on a same test to the currently used one based on heat flow. The results show that the developed metre allows carrying out thermal transmittance measurements in buildings in a cheap, quick, reliable and simple way.

A formal methodology for the analysis and design of nonlinear fuzzy control systems

Stability theory plays a central role in system theory and engineering. Stability of equilibrium points is usually characterized in the sense of Lyapunov. Based on Lyapunov theory, this paper proposes a general methodology that uses fuzzy logic to systematically and formally analyze and synthesize nonlinear control systems, which are stable by design. The proposed methodology avoids searching for Lyapunov functions, which is often a tedious task and unsuccessful outcome. The proposed synthesis procedure is systematic as well as formal and, especially, independent of heuristics.

An Energy Management Strategy and Fuel Cell Configuration Proposal for a Hybrid Renewable System with Hydrogen Backup

This paper presents a new and optimal proposal of energy management strategy for a solar panels/wind turbines/fuel cell/battery/alkaline electrolyzer on grid hybrid power system. These new proposal takes into account technical and economical optimization parameters, improving the system performance, the lifetime of different elements and reducing operation and maintenance cost. The features of the proposed energy management strategy are compared over other strategies found in the scientific literature. Additionally, another key parameter like fuel cell modularity has been considered. That is the effect over the whole system performance of using a single fuel cell with high rate power (PFC) versus a modular configuration built from n stacks with PFC/n rate power each one. Then, joining the new proposed strategy with the optimization parameter regarding the fuel cell modularity, it is possible to get the best solution for this kind of hybrid systems.

Methodology for adapting the parameters of a fuzzy system using the extended Kalman filter

When we try to analyze and to control a system whose model was obtained only based on input/output data, accuracy is essential in the model. On the other hand, to make the procedure practical, the modeling stage must be computationally efficient. In this regard, this paper presents the application of extended Kalman filter for the parametric adaptation of a fuzzy model.

A New Automatic System for Angular Measurement and Calibration in Radiometric Instruments

This paper puts forward the design, construction and testing of a new automatic system for angular-response measurement and calibration in radiometric instruments. Its main characteristics include precision, speed, resolution, noise immunity, easy programming and operation. The developed system calculates the cosine error of the radiometer under test by means of a virtual instrument, from the measures it takes and through a mathematical procedure, thus allowing correcting the radiometer with the aim of preventing cosine error in its measurements.