Diagnosis through Series Connected Photovoltaic Panels by Pulse Power Line Communication Technique

Automatic diagnosis through individual PV panel is especially required for hard to reach locations such as solar rooftop or exterior building. Therefore, a novel solution for diagnosing photovoltaic (PV) panels through their PV string is proposed. Our solution not only measures IV curve of PV panels, but it can also determine disconnected or loose location of power cable. Large pulse communication technique is used to implement this solution to achieve low cost and zero power shut down. Comparison with other existing solutions is also discussed. The proposed technique is implemented on a five-panel PV string. Its satisfactorily testing results are presented under strong and weak sunlight conditions. For further understanding in PV panel, an amorphous silicon PV panel is characterized and also modeled to be a simple equivalent circuit

Electricity from photovoltaic solar cells: Flat-Plate Solar Array Project final report. Volume VI: Engineering sciences and reliability

The Flat-Plate Solar Array (FSA) Project, funded by the U.S. Government and managed by the Jet Propulsion Laboratory, was formed in 1975 to develop the module/array technology needed to attain widespread terrestrial use of photovoltaics by 1985. To accomplish this, the FSA Project established and managed an Industry, University, and Federal Government Team to perform the needed research and development. This volume of the series of final reports documenting the FSA Project deals with the Project's activities directed at developing the engineering technology base required to achieve modules that meet the functional, safety and reliability requirements of large-scale terrestrial photovoltaic systems applications. These activities included: (1) development of functional, safety, and reliability requirements for such applications; (2) development of the engineering analytical approaches, test techniques, and design solutions required to meet the requirements; (3) synthesis and procurement of candidate designs for test and evaluation; and (4) performance of extensive testing, evaluation, and failure analysis to define design shortfalls and, thus, areas requiring additional research and development. During the life of the FSA Project, these activities were known by and included a variety of evolving organizational titles: Design and Test, Large-Scale Procurements, Engineering, Engineering Sciences, Operations, Module Performance and Failure Analysis, and at the end of the Project, Reliability and Engineering Sciences. This volume provides both a summary of the approach and technical outcome of these activities and provides a complete Bibliography (Appendix A) of the published documentation covering the detailed accomplishments and technologies developed

Dispersed storage and generation case studies

Three installations utilizing separate dispersed storage and generation (DSG) technologies were investigated. Each of the systems is described in costs and control. Selected institutional and environmental issues are discussed, including life cycle costs. No unresolved technical, environmental, or institutional problems were encountered in the installations. The wind and solar photovoltaic DSG were installed for test purposes, and appear to be presently uneconomical. However, a number of factors are decreasing the cost of DSG relative to conventional alternatives, and an increased DSG penetration level may be expected in the future

Embedding Power Line Communication in Photovoltaic Optimizer by Modulating Data in Power Control Loop

In Photovoltaic (PV) system, dc-dc power optimizer (DCPO) is an option to maximize output power. At the same time, data links among DCPOs are often required for system monitoring and controlling. This paper proposes a novel power line communication (PLC) method for the DCPOs, in which the data of a DCPO is modulated into the control loop of power converter, and then transmitted through the series-connected dc power line to other DCPOs. In the process of communication, differential phase shift keying (DPSK) modulation and discrete Fourier transformation (DFT) demodulation are employed. To analyze the quality of communication, the communication model of the system is built, based on small-signal model. Furthermore, the noises of the system, including switching, maximum power point tracking (MPPT) and additive white Gaussian noise (AWGN), are discussed and measured to evaluate the signal-to-noise ratio (SNR). At last, an experimental system including 6 DCPOs is established and tested, which verifies the feasibility and effectiveness of the proposed method

Real-time Modelling, Diagnostics and Optimised MPPT for Residential PV Systems

The work documented in the thesis has been focused into two main sections. The first part is centred around Maximum Power Point Tracking (MPPT) techniques for photovoltaic arrays, optimised for fast-changing environmental conditions, and is described in Chapter 2. The second part is dedicated to diagnostic functions as an additional tool to maximise the energy yield of photovoltaic arrays (Chapter 4). Furthermore, mathematical models of PV panels and arrays have been developed and built (detailed in Chapter 3) for testing MPPT algorithms, and for diagnostic purposes.In Chapter 2 an overview of the today’s most popular MPPT algorithms is given, and, considering their difficulty in tracking under variable conditions, a simple technique is proposed to overcome this drawback. The method separates the MPPT perturbation effects from environmental changes and provides correct information to the tracker, which is therefore not affected by the environmental fluctuations. The method has been implemented based on the Perturb and Observe (P&O), and the experimental results demonstrate that it preserves the advantages of the existing tracker in being highly efficient during stable conditions, having a simple and generic nature, and has the benefit of also being efficient in fast-changing conditions. Furthermore, the algorithm has been successfully implemented on a commercial PV inverter, currently on the market. In Chapter 3, an overview of the existing mathematical models used to describe the electrical behaviour of PV panels is given, followed by the parameter determination for the five-parameter single-exponential model based on datasheet values, which has been used for the implementation of a PV simulator taking in account the shape, size ant intensity of partial shadow in respect to bypass diodes.In order to eliminate the iterative calculations for parameter determinations, a simplified three-parameter model is used throughout Chapter 4, dedicated to diagnostic functions of PV panels. Simple analytic expressions for the model important parameters, which could reflect deviations from the normal (e.g. from datasheet or reference measurement) I −V characteristic, is proposed.A considerable part of the thesis is dedicated to the diagnostic functions of crystalline photovoltaic panels, aimed to detect failures related to increased series resistance and partial shadowing, the two major factors responsible for yield-reduction of residential photovoltaic systems.Combining the model calculations with measurements, a method to detect changes in the panels’ series resistance based on the slope of the I − V curve in the vicinity of open-circuit conditions and scaled to Standard Test Conditions (STC) , is proposed. The results confirm the benefits of the proposed method in terms of robustness to irradiance changes and to partial shadows.In order to detect partial shadows on PV panels, a method based on equivalent thermal voltage (Vt) monitoring is proposed. Vt is calculated using the simplified three-parameter model, based on experimental curve. The main advantages of the method are the simple expression for Vt, high sensitivity to even a relatively small area of partial shadow and very good robustness against changes in series resistance.Finally, in order to quantify power losses due to different failures, e.g. partial shadows or increased series resistance, a model based approach has been proposed to estimate the panel rated power (in STC). Although it is known that the single-exponential model has low approximation precision at low irradiation conditions, using the previously determined parameters it was possible to achieve relatively good accuracy. The main advantage of the method is that it relies on already determined parameters (Rsm, Vt) based on measurements, therefore reducing the errors introduced by the limitation of the single-exponential model especially at low irradiation conditions

Active Power Control of a PV Generator for Large Scale Photovoltaic Power Plant

Controllo di potenza attiva per impianti fotovoltaici di grande taglia senza energy storage. Descrizione dei grid code requirements, tendenze attuali mercato voltaico. Descrizione modello cella fotovoltaica, modello dell'inverter e del suo controllo. Algoritmo modificato per taglio di potenza attiva con valore fisso di potenza. Analisi economico-comparativa tra una soluzione con energy storage e senza energy storage per il taglio di potenza attiva

A Cascaded Inverter For Transformerless Single Phase Grid Connected Photovoltaic Systems

The design and control issues associated with the development of single phase grid-connected photovoltaic system incorporating a multi-level cascaded inverter are discussed in this paper. The advantages of transformer less inverter over a full-bridge inverter in combination with a line frequency transformer which is a common topology has been described in this report. Attractive features of multi-level inverters have been studied and descriptive details of photovoltaic system along with control and grid synchronization has been given this paper. Simulation results are presented to demonstrate the suitability of the control method

Real-time fault detection in photovoltaic power plants

Climatic changes are one of the biggest problems that humanity faces and renewable energies are a big weapon to fight this threat. Solar energy is one of the renewable energy sources in current use and to produce this type of energy there are several solar plants placed across the country. These giant plants are made of many sets of solar panels (called arrays) which are responsible for converting solar energy into electricity. One of the critical aspects of these plants' operation is the early detection of solar panel malfunctions. The current methods in use are expensive and consume a lot of time, meaning that, in some cases, the faults are detected only a year later, causing a huge financial impact on the companies responsible for the plants' operation. To cut these losses and to detect the faults as early as possible, this dissertation presents a real-time system capable of detecting malfunctions in a solar panel array. The node should be placed in the array's junction box and detects if an array has a faulty panel. The faults are detected comparing the array's output (voltage and current) with the output of an artificial neural network that models the array's behaviour using the real-time solar irradiance and temperature values. The neural network uses the measured values to carry out an online learning process, improving the network performance. Due to the plant's extension, a low power wide area network (LORAWAN), is used to send the array status and the data collected to the cloud, where they are processed and presented in a dashboard

Flat-plate solar array project. Volume 6: Engineering sciences and reliability

The Flat-Plate Solar Array (FSA) Project activities directed at developing the engineering technology base required to achieve modules that meet the functional, safety, and reliability requirements of large scale terrestrial photovoltaic systems applications are reported. These activities included: (1) development of functional, safety, and reliability requirements for such applications; (2) development of the engineering analytical approaches, test techniques, and design solutions required to meet the requirements; (3) synthesis and procurement of candidate designs for test and evaluation; and (4) performance of extensive testing, evaluation, and failure analysis of define design shortfalls and, thus, areas requiring additional research and development. A summary of the approach and technical outcome of these activities are provided along with a complete bibliography of the published documentation covering the detailed accomplishments and technologies developed