Generalized formulation to estimate the Supercapacitor’s R-C series impedance using fractional order model

The main objective of this paper is to develop a new technique for the supercapacitor’s parameter identification that can handle the issue of initial voltage. An effective approach is proposed using the fractional-order derivative for accurate identification of a well-known series Resistance-Capacitance (R-C) model. An expression is derived using the Caputo definition and the Haar wavelet operational matrix, which is sufficient for both charging and discharging phase data of supercapacitors. To extract impedance parameters, voltage stimulated step response is utilized and parameters are calculated despite random initial voltage stored in a supercapacitor. This operational matrix approach transforms complex fractional derivative terms into simple algebraic expressions and reduces the overall complexity. The proposed technique shows a very good agreement with experimental data that exhibit different initial voltages and different time-frames. Investigations and experiments with various supercapacitors clearly reveal the importance of the developed equation for a fractional R-C model

Fractional - order system modeling and its applications

In order to control or operate any system in a closed-loop, it is important to know its behavior in the form of mathematical models. In the last two decades, a fractional-order model has received more attention in system identification instead of classical integer-order model transfer function. Literature shows recently that some techniques on fractional calculus and fractional-order models have been presenting valuable contributions to real-world processes and achieved better results. Such new developments have impelled research into extensions of the classical identification techniques to advanced fields of science and engineering. This article surveys the recent methods in the field and other related challenges to implement the fractional-order derivatives and miss-matching with conventional science. The comprehensive discussion on available literature would help the readers to grasp the concept of fractional-order modeling and can facilitate future investigations. One can anticipate manifesting recent advances in fractional-order modeling in this paper and unlocking more opportunities for research

A single-step identification strategy for the coupled TITO process using fractional calculus

The reliable performance of a complete control system depends on accurate model information being used to represent each subsystem. The identification and modelling of multivariable systems are complex and challenging due to cross-coupling. Such a system may require multiple steps and decentralized testing to obtain full system models effectively. In this paper, a direct identification strategy is proposed for the coupled two-input two-output (TITO) system with measurable input–output signals. A well-known closed-loop relay test is utilized to generate a set of inputs–outputs data from a single run. Based on the collected data, four individual fractional-order transfer functions, two for main paths and two for cross-paths, are estimated from single-run test signals. The orthogonal series-based algebraic approach is adopted, namely the Haar wavelet operational matrix, to handle the fractional derivatives of the signal in a simple manner. A single-step strategy yields faster identification with accurate estimation. The simulation and experimental studies depict the efficiency and applicability of the proposed identification technique. The demonstrated results on the twin rotor multiple-input multiple- output (MIMO) system (TRMS) clearly reveal that the presented idea works well with the highly coupled system even in the presence of measurement noise

Impact of Stray Voltage on Renewable Energy-based Farm in Pacific Island Country

Recent advancements in solar technology offer an enormous opportunity for the people of Pacific Islands to use electricity from the off-grid solar system for both their energy needs and farming activities. However, a farm’s productivity and animal health might be seriously threatened if it experiences stray voltages caused by the improper grounding of its installed electrical systems. As a shift in the neutral point of an electrical system creates a current flow to the ground through conducting elements, the impacts of stray voltages need to be addressed from both technical and economic viewpoints. In this research, the effects of stray voltages passing through animals are explored using circuit designs for solar sources considering variable grounding resistances due to the different body resistances of various types of animals, and environmental and grounding design issues. A comparison of the stray voltages of two different sources (off-grid solar and traditional grid) with various configurations are conducted to determine their effects on a farm. Finally, their economic impacts together with possible techniques for mitigating them are explained

Impact of Stray Voltage on Renewable Energy-based Farm in Pacific Island Country

Recent advancements in solar technology offer an enormous opportunity for the people of Pacific Islands to use electricity from the off-grid solar system for both their energy needs and farming activities. However, a farm’s productivity and animal health might be seriously threatened if it experiences stray voltages caused by the improper grounding of its installed electrical systems. As a shift in the neutral point of an electrical system creates a current flow to the ground through conducting elements, the impacts of stray voltages need to be addressed from both technical and economic viewpoints. In this research, the effects of stray voltages passing through animals are explored using circuit designs for solar sources considering variable grounding resistances due to the different body resistances of various types of animals, and environmental and grounding design issues. A comparison of the stray voltages of two different sources (off-grid solar and traditional grid) with various configurations are conducted to determine their effects on a farm. Finally, their economic impacts together with possible techniques for mitigating them are explained

Fractional - order impedance identification for Inductors

The accuracy of a model is required to represent the integrated device in any electrical system for quality assurance. This article intends to measure the accurate and realistic impedance of the inductor, called pseudo-inductance. For this purpose, we have applied fractional-order modeling and a simple scheme to estimate the impedance value of the inductor (or inductive coils). Also, the approach does not require any high-end measurement device like the impedance meter. The complexity of the fractional-order derivative for identification purpose is simplified using the block-pulse-operational-matrix. The complexity of the fractional-order derivative for identification purpose is simplified using the block-pulse operational matrix to approximate the time response behaviour in terms of the inductor model’s parameters. The study goes on to highlight the importance of fractional derivative and its interpretation in terms of the phase difference. The proposed model can be used to accurately model any inductor based on its time response data. The purpose of the study is validated through the experimental results

Model of fractional - order resonant wireless power transfer system for optimal output

Wireless Power Transfer (WPT) technology has recently gained popularity in applications and research topics. It enables the transfer of electrical energy from a source to a load without connecting wires physically. The WPT system is commonly studied classically using integer order capacitors and inductors. Nonetheless, such integer order based systems have drawbacks, such as low output power, poor transmission efficiency and sensitivity to parameter variations. This paper proposes a fractional order resonant WPT circuit whereby both the transmitting and receiving ends are composed of a fractional capacitor and inductor to overcome such problems. In this paper, the overall performance is studied based on its output power and efficiency considering a series-parallel topology. The effect of fractional order in fractal elements will be analyzed to observe the optimal combination of components to achieve the maximum output power with higher efficiency. Through a comparative analysis of the results, several combinations of circuit parameters can provide a theoretical understanding for implementing an experimental system

Change detection of a coastal woodland mangrove forest in Fiji by integration of remote sensing with spatial mapping

Mangroves play key ecological role in structuring the availability of coastal resources. The current study was focused on change detection in a large mangrove patch located in Votua area of the Ba province in Fiji. Globally, the mangrove population continues to decline with the changes in climatic conditions and anthropo-genic activities. Baseline information through wetland maps and time series change are essential references for the development of effective mangrove management plans. These maps reveal the status of the resource over a period of time and the impacts from anthropogenic activities. Remote sensing techniques were integrated with geographic information system tools for mapping and detecting temporal change over a period of 20 years. Remotely sensed imagery data from Landsat satellite was sourced from the year 1999 to 2018 for this investigation. The mapping analysis of temporal changes in mangrove forests was carried using the versatile ArcGIS and ENVI software. The pilot change detection analysis revealed a small but important change in the mangrove patch over these years. Landward creep of mangroves was also detected. The outcomes of this study serve as baseline and conservation information for the development and implementation of effective management plans for one of Fiji’s largest mangrove patches

Flexible fractional supercapacitor model analyzed in time domain

Supercapacitors have been rapidly adopted to replace batteries in many instances from power tools to automotive and aviation. Designing systems incorporating supercapacitors necessitate an accurate model of supercapacitor to maintain system efficiency. However, due to varying impedance property of supercapacitor, modeling becomes critical with likelihood of introducing errors. This work proposes an enhanced model to predict the system dynamics under various initial state of charge in supercapacitors. The proposed flexible model is suitable to represent actual supercapacitor impedance without prior assumption on the model structure. The use of one model to cover the other various impedance structures is simple and possible to estimate accurate supercapacitor’s impedance. Selection of impedance structure is self-regulated to improve the accuracy with minimum variables. To illustrate the variable structure fractional model, experimental results are shown with three different values of supercapacitors from three different manufacturers

Fractional impedance of supercapacitor: an extended investigation

There has been an impressive growth rate of supercapacitor’s applications, which urges a need for an in-depth investigation on modeling of supercapacitor in order to study the behavior and designing systems integrated with it. Studies have been carried out in multiple domains, but the time domain based modeling has been a simple and commonly adopted study. This research proposes the block-pulse based identification method for modeling the time response behavior of the supercapacitor. The proposed method for modeling supercapacitor simplifies fractional derivative into simple algebra rather than direct complex function like the Mittag-Leffler function. Furthermore, in this paper the critical observation is conducted with varied time duration of data collected for modeling of the supercapacitor of same brand and capacity. It shows how its parameters are affected by time length despite capturing full charge and discharge cycles. This may help in the crucial stage of determining the sample size or the data length for which modeling is to be performed. Some recommendations have been made after systematic observations on three different branded supercapacitors of same capacitance. Using the proposed technique, one can estimate the model parameters set to handle complexity posed by fractal behavior of supercapacitors