Juan M. Enrique

A New and Inexpensive Pyranometer for the Visible Spectral Range

This paper presents the design, construction and testing of a new photodiode-based pyranometer for the visible spectral range (approx. 400 to 750 nm), whose principal characteristics are: accuracy, ease of connection, immunity to noise, remote programming and operation, interior temperature regulation, cosine error minimisation and all this at a very low cost, tens of times lower than that of commercial thermopile-based devices. This new photodiode-based pyranometer overcomes traditional problems in this type of device and offers similar characteristics to those of thermopile-based pyranometers and, therefore, can be used in any installation where reliable measurement of solar irradiance is necessary, especially in those where cost is a deciding factor in the choice of a meter. This new pyranometer has been registered in the Spanish Patent and Trademark Office under the number P200703162.

A new approach to obtain I-V and P-V curves of photovoltaic modules by using DC-DC converters

The achievement of I-V and P-V curves of photovoltaic modules gives the possibility of obtaining their characteristic parameters: the short-circuit current (I/sub sc/), the open-circuit voltage (V/sub oc/), the maximum power point (MPP) and the fill factor (FF). These values are significant for the design of a photovoltaic system. These curves depend on the global irradiance (G), the temperature (T) and the spectral distribution of the solar irradiation. In this paper, a new methodology to determine the afore mentioned curves by using DC-DC converters is proposed. This methodology allows carrying out the complete sweep of the voltage and the current (including V/sub oc/ and I/sub sc/). Regarding the traditional methods, this new one provides the following advantages: a) minimum power loss with regard to the systems that operate in lineal zone (active zone); this implies several advantages in size and cost; and b) this new method allows an automatic adaptation of the interpolation interval.

A new application of the coupled-inductors SEPIC converter to obtain I-V and P-V curves of photovoltaic modules

The achievement of I-V and P-V curves of photovoltaic modules gives the possibility to obtain the exact operation point, the short-circuit current (Isc), the open-circuit voltage (Voc), the maximum power point (MPP) and the fill factor (FF). These are significant parameters for the design and for the start-up of a photovoltaic installation. In this paper, we propose and analyse by means of simulation the capacity of the SEPIC (single-ended primary inductance converter) structure to implement I-V and P-V curves tracers of photovoltaic modules, mainly because the SEPIC topology presents the capability of buck-boost conversion. Thanks to this property, a complete sweep of the voltage and the current given by a photovoltaic panel can be made, including Voc and Isc . This structure is implemented by coupled inductors and presents two fundamental advantages: 1) it allows to emulate a resistance at the input converter within the range [0,infin) and 2) it guarantees a null ripple in the input current when the magnetic coupling of his two inductors fulfils ZRC (zero ripple condition)

Determination of PV Generator I-V/P-V Characteristic Curves Using a DC-DC Converter Controlled by a Virtual Instrument

A versatile measurement system for systematic testing and measurement of the evolution of the I-V characteristic curves of photovoltaic panels or arrays (PV generators) is proposed in this paper. The measurement system uses a circuit solution based on DC-DC converters that involves several advantages relative to traditional methods: simple structure, scalability, fast response, and low cost. The measurement of the desired characteristics of PV generators includes high speed of response and high fidelity. The prototype system built is governed by a microcontroller, and experimental results prove the proposed measurement system useful. A virtual instrument (VI) was developed for full system control from a computer. The developed system enables monitoring the suitable operation of a PV generator in real time, since it allows comparing its actual curves with those provided by the manufacturer.

Temperature Measurement in PV Facilities on a Per-Panel Scale

This paper presents the design, construction and testing of an instrumentation system for temperature measurement in PV facilities on a per-panel scale (i.e., one or more temperature measurements per panel). Its main characteristics are: precision, ease of connection, immunity to noise, remote operation, easy scaling; and all of this at a very low cost. The paper discusses the advantages of temperature measurements in PV facilities on a per-panel scale. The paper presents the whole development to implementation of a real system that is being tested in an actual facility. This has enabled the authors to provide the readers with practical guidelines, which would be very difficult to achieve if the developments were implemented by just simulation or in a theoretical way. The instrumentation system is fully developed, from the temperature sensing to its presentation in a virtual instrument. The developed instrumentation system is able to work both locally and remotely connected to both wired and wireless network.

Method and Device for Measuring Characteristic Curves in Photovoltaic Systems

The invention relates to a measuring device that can capture the characteristic curves in photovoltaic systems, such as current versus voltage (I-V) and power versus voltage (P-V) of a solar cell (CS), of a photovoltaic panel (PV) or of a group of same. The invention is characterised in that it is formed by one or more DC/DC converters (10) [Direct Current/Direct Current], one or more solar cells (20) or photovoltaic panels (30), a capture and display device (40) and a control circuit (50) connected to the converters.

Discovering the dynamic behavior of unknown systems using fuzzy logic

To know the dynamic behavior of a system it is convenient to have a good dynamic model of it. However, in many cases it is not possible either because of its complexity or because of the lack of knowledge of the laws involved in its operation. In these cases, obtaining models from input–output data is shown as a highly effective technique. Specifically, intelligent modeling techniques have become important in recent years in this field. Among these techniques, fuzzy logic is especially interesting because it allows to incorporate to the model the knowledge that is possessed of the system, besides offering a more interpretable model than other techniques. A fuzzy model is, formally speaking, a mathematical model. Therefore, this model can be used to analyze the original system using known systems analysis techniques. In this paper a methodology for extract information from unknown systems using fuzzy logic is presented. More precisely, it is presented the exact linearization of a Takagi–Sugeno fuzzy model with no restrictions in use or distribution of its membership functions, as well as obtaining its equilibrium states, the study of its local behavior and the search for periodic orbits by the application of Poincaré.

An Application of Interleaved Zeta-Buck-Boost Combination Converter in Distributed Generation

Low-voltage bipolar-type DC microgrid is an emerging alternative for electric systems with high penetration of distributed generation (DG). The DG sources usually generate energy in DC form. This type of generation needs an interface to adapt the level of voltage from the source to the network. These interfaces usually consist of DC-DC converters. In this work, a new DC-DC converter is proposed for this application. This topology allows obtaining a DC bipolar output from a single DC input. The new converter consists of combining two basic converters, Zeta and Buck-Boost single inductor converter sharing the switch. It is possible because both converters have the same instantaneous duty cycle. For high power, various combined converters connected in parallel and operating in interleaved mode is proposed. This configuration gives high power with low ripple at the output and input currents. An analysis of the proposed configuration for different performance modes and load conditions is carried out. Simulation results show as this interleaved converter topology with appropriated modulation schemes is adequate to use in bipolar DC microgrid (MG).

Comparative Analysis of the Tracking Efficiency of a Maximum-Power Point Tracker Based on Maximum-Power Point Resistance Modeling Versus a Classic P&O

In this paper a comparative analysis of the tracking efficiency reported by two tracking systems of the maximum power point (MPPT) of a photovoltaic (PV) generator is carried out.