Electrical Reconfiguration Research Articles

Performance and Reliability Improvement of Partially Shaded PV Arrays by One-Time Electrical Reconfiguration

Partial shading is the most unexpected scenario encountered by the arrays that degrade the performance causing power reduction, non-convex characteristics curves, losses, hotspot, module damage, and system failure. The adoption of various reconfiguration techniques has recently provided relief to the PV array to reduce power losses during partial shading. However, these techniques exhibit vulnerabilities such as reliable operation, ease of implementation and, higher cost and complexity due to the requirement of abundant manpower, labour, complex algorithms, dynamic operation, switches and sensors that cause additional power losses. Hence, this paper presents a low cost and less complex reconfiguration technique for PV arrays to effectively increase the power generation during partial shading scenarios. The proposed reconfiguration does not require any manpower, labour, algorithms or additional devices to reduce the losses in arrays during shading. The efficacy of the technique is tested using two array sizes under various shading scenarios using MATLAB modelling and real-time field experiments. Also, for better analysis, the performance of the proposed technique is compared with conventional configurations and Sudoku reconfiguration. The investigation proclaimed that the proposed reconfiguration technique has an average power enhancement of 20% higher than any other conventional configurations.

A novel on-time partial shading detection technique for electrical reconfiguration in solar PV system

Mismatch losses due to partial shading condition (PSC) is not permitted to extract maximum power from the solar PV array. Numerous techniques were proposed to reduce the partial shading effect. But the major problem is in finding out the occurrence and its distribution of the partial shading in the solar PV array. Conventional methods disconnect the load temporally from the PV array and measure the short circuit current (Isc) and use the information to detect the partial shading. Frequent disconnection of the solar PV array from the load makes the conventional method unpractical in a large solar power plant and even a stand-alone PV system. A novel on-time partial detection technique is proposed in this paper and useing difference in row voltage (Vd) instead of the short circuit current (Isc) to estimate the partial shading. Greater the Vd infers the severity of occurrence of the partial shading in the solar PV array. By using a static reconfiguration and then a modified couple matching (MCM) technique the voltage difference (Vd) gets reduced. This will ensure the mitigation of the PSC. As in this proposed technique, the load never be disconnected from the solar PV array, to detect the partial shading, it can be used practically even for a stand-alone PV system. Eight extensive partial shading patterns are simulated using MATLAB Simulink to validate the proposed work and the size of 3 × 4 120 W polycrystalline PV panel array is used for the experimental validation.

Electrophoretic Plasmonic Ink for Dynamic Color Display

AbstractPlasmonic metal nanostructures generate vivid colors with high spatial resolution. Active control of plasmonic pixels by electrical means, which is compatible with integrated circuit technologies, is a promising technique for dynamic full color reflective display. However, the development of electrical plasmonic display is still limited by the difficulties in cost‐effective construction of active plasmonic pixels over large areas. This study demonstrates the achievement of electrical plasmonic display in full color by electrophoretic movement control of plasmonic noble metal nanocrystals in an organic electrolyte solvent. The persistent issues of nanoparticle aggregation and irreversible deposition in electrophoresis are addressed through appropriate surface modifications of the plasmonic nanocrystals, enabling them as advantageous nanoscale colorful pigments with long‐term durability. A weak electric field therefore allows color display with high contrast, high saturation, and electrical reconfigurability. The ink containing plasmonic pigments is further assembled into microfluidic chips to display different characters. The strategy will pave the way towards the development of plasmonic electronic paper in full color.

Nonreciprocal filtering power dividers

We propose the concept of nonreciprocal filtering power dividers, which are compact devices able to merge the functionalities of power dividers and combiners, the selectivity of bandpass filters, and magnetless nonreciprocity from time-modulation. A prototype of this type of devices operating at microwaves has been implemented in microstrip technology. The device is composed of a Wilkinson power divider integrated with two identical microstrip filters based on quarter-wavelength coupled lines. The resonators of the filters are terminated with varactors that are time-modulated using low-frequency harmonic signals from a Coplanar Waveguide (CPW) feeding network printed on the ground plane of the microstrip structure. The resulting compact device behaves as a nonreciprocal power divider, nonreciprocal power combiner, or a common filtering power divider depending on the modulation parameters. In addition, it exhibits electrical frequency reconfigurability (over 15%), high rejection out of the passband, and enhanced isolation among the ports. A manufactured prototype shows relative fractional bandwidth of 3.1% measured at a return loss level of 11 dB, and insertion losses of 5.9 dB, together with a nonreciprocal response with over 21 dB of directivity at the center frequency.

Non-Volatile RF Reconfigurable Antenna on Flexible Substrate for Wireless IoT Applications

To date semiconductor switches are still the main enablers for electrical circuit and system reconfigurability. They however not only consume dynamic power but also dissipate static power, the former for performing on/off operation and latter for holding on/off state. These semiconductor devices are volatile and not energy efficient due to the need for holding voltage and can significantly increase the system power consumption where hundreds and thousands of switches are needed, such as in large reconfigurable intelligent surfaces and large antenna arrays. In this work, we report a non-volatile reconfigurable antenna that can switch between dual-band at 2.4 GHz and 5 GHz to a single band at 3 GHz. The measured results including reflection, gain and radiation patterns reveal promising performance, experimentally demonstrating a new approach of design and realization of RF switch integrated multi-band reconfigurable antennas. This zero-static power mechanism, along with easy fabrication on the flexible substrates would be very beneficial for Internet of Things (IoT) applications.

A coordinated restoration method of electric buses and network reconfiguration in distribution systems under extreme events

A coordinated restoration method of electric buses and network reconfiguration in distribution systems under extreme events

Electric vehicles reactive power management and reconfiguration of distribution system to minimise losses

This study investigates the optimal operation of distribution feeder reconfiguration (DFR) strategy in smart distribution system integrated with electric vehicles (EVs) and wind power generation. A two-stage framework is proposed for real and reactive power management and DFR. In the first stage, demand dispatch of EVs is coordinated to utilise available wind power and minimise the total load variations. In the second stage, a comprehensive problem formulation is developed to minimise the losses in the system with simultaneous EVs reactive power management and DFR. A genetic algorithm is used to solve this two-stage optimisation problem. A case study of 33-bus radial distribution system is presented to highlight the efficacy of proposed approach. The obtained results are quantitatively assessed in terms of losses and node voltages. A comparative benchmarking analysis is presented to substantiate the role of DFR and reactive power capability of EVs in improving the system performance.

A tunable balanced dual‐band BPF with quasi‐independently controlled center frequency and bandwidth

In this paper, a balanced dual-band bandpass filter (BPF) with high selectivity and low insertion loss performance is presented by employing stub loaded resonators (SLRs) and stepped impedance resonators (SIRs) into balanced microstrip-slotline (MS) transition structures. The balanced MS transition structures can achieve a wideband common-mode (CM) suppression which is independent of the differential-mode (DM) response, significantly simplifying the design procedure. Six varactors are loaded into the resonators to achieve the electrical reconfiguration. The proposed balanced dual-band BPF can realize quasi-independently tunable center frequencies and bandwidths. A tuning center frequency from 2.48 to 2.85 GHz and a fractional bandwidth (20.16%-7.02%) with more than 15 dB return loss and less than 2.36 dB insertion loss are achieved in the first passband. The second passband can realize a tuning center frequency from 3.6 to 3.95 GHz with more than 12 dB return loss and less than 2.38 dB insertion loss. A good agreement between the simulated and measured results is observed.

Experimental investigation on output power enhancement of partial shaded solar photovoltaic system

ABSTRACT There are various factors that contribute towardsthereduction of output power from photovoltaic (PV) arrays. One of the major factors is thepartial shading. Partial shading is caused by the passage of clouds and thepresence of buildings, towers, and trees. Shading affects the power generation of the PV system. It needs support to survive even under shading conditions. Conventionally partial shading is identified by measuring the open-circuit voltages and short circuit currents of the PV panels by isolating the load from thePV array. But the proposed methodidentifies the partial shading without isolating the load from thePV array by using a normal camera. This method is more sensitive toward any disturbance in the system performance. A digital camera is used to capture the image of the PV array, and then by using the image processing techniques,partialshadingis identified. The proposed method uses therelay circuit to do electrical reconfiguration to enhance the power output during partial shading conditions. The control signals for the relays are generated based on the partial shading. In the proposed method,acamera is interfaced with MATLAB, and the captured images are processed instantly to detect the fault or partial shading. Then the reconfiguration signals are given through MATLAB-Arduino interface to the relay circuits in the PV array, which in turn reconfigures the PV array for better output power generation. The proposed method is tested in 80 W solar PV system, which enhances the power by 12%. It is suitable for the small-sized solar PV power plants ranging from 1 kW to 5 kW.

Performance Analysis of Partially Shaded Photovoltaic Array Using Magic Square View Configuration for Shade Dispersion

Abstract The power generated by the photovoltaic (PV) array is affected by the partial shading, caused by the neighboring object shadows, dirtiness, moving clouds, bird droppings, different orientation angles of PV modules, deposition of dust in modules, and the physical location of the PV module. Therefore, the PV systems exhibit multiple peaks of generated power and do not always track the maximum power point (MPP). Thus, to overcome these problems of multiple peaks, the PV panels are reconfigured using either electrical or physical reconfiguration methods. The main aim of this paper is to investigate the performance of magic square view (MSV) configuration of PV modules under partial shading conditions (PSCs). For validation, three kinds of PSCs patterns are considered and are then compared to the Total Cross Tied (TCT) and Sudoku (SDK) configurations: long and wide, short and narrow, and long and narrow. Overall, the obtained results show that the MSV configuration allows us to increase the power generated by the PV array by 34% and 7% under the three types of shadow studied as compared to the TCT and SDK configurations, respectively. The PV array configurations parameters are performed based on matlab/simulink software. The simulation and performance analysis of PV array configurations is performed with 81 PV modules of BP Solar Poly BP 380 modules.

Electrical Reconfiguration Techniques for Frequency Agility in Patch Antennas

Wireless Systems are subjected to overwhelming advancements with the exponential demands in the field of Communication. This has led to the evolution of Reconfigurable antennas which gained enough significance as they are capable of modifying them.selves to different operating frequencies, patterns or polarizations. Out of these, Frequency Reconfigurable Antennas which can be operated at multi-frequency environment have been found to have a wide range of applications. The reconfiguration can be achieved using various switching mechanisms like, electrical, optical, etc. These are found to support various communication standards, ensure effective utilization of spectrum, reduce system complexity and hence cost. The recent researches on frequency reconfigurable antennas using electrical switches are analyzed in this paper based on their performances and a comparison on various switching techniques is presented.

Network Reconfiguration for an Electric Distribution System with Distributed Generators based on Symbiotic Organisms Search

This paper proposes a method of network reconfiguration based on symbiotic organisms search (SOS) algorithm for reducing power loss of the electric distribution system. The SOS is a recent developed meta-heuristic algorithm inspired from the symbiotic interaction strategies of organisms for surviving and propagating in the ecosystem. Compared to other algorithms, SOS does not need any control parameters during the searching process. The advantages of the proposed SOS method have been validated in two electric distribution systems. Three network cases have been considered for each system, consisting of performing network reconfiguration on the system without distributed generator (DG) placement, the system installed type-P DGs and the system installed type-PQ DGs. The comparison results with particle swarm optimization and other previous methods show that the proposed SOS can be a promising technique for the problem of electric network reconfiguration.

Practical implementation of real-time cognitive radio energy detector using frequency reconfigurable filtenna

ABSTRACTIn this paper, a new design of cognitive radio (CR) system based on a reconfigurable filtenna, RF power detector, and Raspberry pi is proposed. It provides a fast and cheap solution to efficiently detect the spectrum holes over the frequency range from 2.37 to 3.69 GHz. The frequency scanning is performed by using a compact narrow bandwidth filtenna. The electrical frequency reconfiguration is achieved by incorporating a varactor diode into the filtenna structure. Under the control of Raspberry pi, the frequency tuning is done by varying the voltage across the varactor from 0 to 30 Volts. Followed by the filtenna, an RF power detector circuit is utilized to monitor the primary user (PU) existence. Different scenarios of measurements are carried out to verify the reliability and successfulness of the proposed prototype.

A Filtering Power Divider with Tunable Center Frequency and Wide Stopband

AbstractIn this paper, a tunable power divider (PD) with a good band-pass filtering response using quarter-wavelength stepped impedance resonators (SIRs) is presented. By appropriately adjusting the impedance and electrical length ratio of SIR, the proposed structure can achieve wide stopband performance. Meanwhile, four varactor diodes are loaded to the external resonators to achieve electrical reconfiguration. In addition, a pair of transmission zeros (TZs) can be generated by applying source and load coupling on each side of the passband, which can effectively improve passband selectivity and out-of-band rejection. In order to verify the feasibility of the proposed design method, a prototype circuit of the proposed filtering power divider (FPD) with tunable center frequency is simulated, fabricated and measured. A good agreement between the simulation and measurement results is observed.

Issue: Selected paper of OIPE 2016 on modeling and optimal design of electromagnetic and electronic devices

Issue: Selected paper of OIPE 2016 on modeling and optimal design of electromagnetic and electronic devices

Power and mismatch losses mitigation by a fixed electrical reconfiguration technique for partially shaded photovoltaic arrays

Abstract Partial shading is the most commonly occurring scenario among the modules of the photovoltaic arrays invoking power and mismatch losses. To attenuate these losses, various interconnection topologies for partial shading mitigation have been proposed in the literatures. This paper proposes a fixed electrical reconfiguration technique for the modules that facilitates distribution of the effect of shading in the entire array thereby reducing the losses caused by partial shading. The technique proceeds with renumbering of the modules according to the proposed algorithm followed by electrical rewiring. The entire study has been accomplished by using MATLAB/Simulink environment and field experiment for the arrays of different sizes. The validity of the proposed technique has been critically evaluated using various artificially created shadings and compared with the hitherto known conventional and hybrid topologies. The response of the array having various topologies for every shade condition has been analysed using the characteristics curves and various performance parameters. From the study, it has been found that the proposed technique excels in performance in terms of reducing the number of peaks in the characteristics curves and maximizing power generation during all shade scenarios as compared to other topologies.

Heuristic optimization of electrical energy systems: Refined metrics to compare the solutions

Many optimization problems admit a number of local optima, among which there is the global optimum. For these problems, various heuristic optimization methods have been proposed. Comparing the results of these solvers requires the definition of suitable metrics. In the electrical energy systems literature, simple metrics such as best value obtained, the mean value, the median or the standard deviation of the solutions are still used. However, the comparisons carried out with these metrics are rather weak, and on these bases a somehow uncontrolled proliferation of heuristic solvers is taking place. This paper addresses the overall issue of understanding the reasons of this proliferation, showing a conceptual scheme that indicates how the assessment of the best solver may result in the unlimited formulation of new solvers. Moreover, this paper shows how the use of more refined metrics defined to compare the optimization result, associated with the definition of appropriate benchmarks, may make the comparisons among the solvers more robust. The proposed metrics are based on the concept of first-order stochastic dominance and are defined for the cases in which: (i) the globally optimal solution can be found (for testing purposes); and (ii) the number of possible solutions is so large that practically it cannot be guaranteed that the global optimum has been found. Illustrative examples are provided for a typical problem in the electrical energy systems area-distribution network reconfiguration. The conceptual results obtained are generally valid to compare the results of other optimization problems.

Self-Rectifying DNTT Memristors

In this letter, a new method for obtaining dynamic hysteresis in flexible thienoacene-based diodes is reported. A major strategy lies in the incorporation of a polymeric interlayer for dual purposes: the polarity inversion and memory effect. It is discovered that the proposed interface engineering transforms a regular organic diode into an efficient self-rectifying memristor, a highly desirable element for emerging neuromorphic applications. An electrical reconfiguration mechanism based on the field behavior at the blocking junction is conceptualized as a guideline for research on related materials and devices.

Design and testing of two phase array reconfiguration procedure for maximizing power in solar PV systems under partial shade conditions (PSC)

Array reconfiguration methods for PV arrays generally follow puzzle based mathematical methods for relocating PV modules. Being size constrained, no array reconfiguration techniques in literature is a reliable solution for effective shade dispersion in large sized PV arrays. Moreover, most of the physical relocation methods do not possess a well-defined and proven methodology to disperse the shade effect of a PV array irrespective of the system architecture. Hence, in this paper, a new two phase method compatible for PV arrays of any size is outlined and tested for effective shade dispersion. Having two different phases in shade dispersion process, the two-phase technology is found highly commendable in relocating PV panels such that illustrious shade dispersion is attained. To confirm its contribution in physical relocation scheme, four shade cases are considered and tested with other methods in literature. Furthermore, based on row current calculation and bypass effect, a quantitative comparison is also performed with popular physical relocation (SuDoKu), electrical reconfiguration (PSO) and conventional (TCT) interconnection schemes. As the results suggest, the fill factor attainment for the proposed two phase method for short wide case, long wide, short narrow and long narrow cases are 72%, 62%, 81% and 75% respectively. Furthermore, except for a single pattern, the power attainment with proposed method has benchmarked minimal of 700 W power improvement compared to TCT in all shade cases.

A novel Competence Square based PV array reconfiguration technique for solar PV maximum power extraction

The ever growing interest on solar energy has augmented large solar power parks in the contemporary time. Even though the most commonly used Total Cross Tie (TCT) interconnection scheme minimizes mismatch losses, shade occurrence in large PV arrays drastically reduces the power output and invokes multiple power peaks in the P-V characteristics. To counteract the multiple peak issue, PV arrays are reconfigured either via electrical or physical reconfiguration techniques. In this regard, physical relocation methods are proven to be efficient and economical in achieving better shade dispersion since, it neither demands complex switching arrangements or high end controllers for reconfiguration. Therefore, this paper introduces an innovative Competence Square (CS) technique for physical rearrangement of PV panels in a TCT interconnection scheme. The method devised is a onetime relocation technique that follows a unique number pattern for relocating the PV panels. Moreover, various test results elucidate the effectiveness of the CS technique in effectively dispersing the shade over the entire PV array. For validation, four typical shade cases are considered and the results are comprehensively compared with the recently proved TCT and Dominance Square (DS) techniques. In addition, the proposed method is computationally easy and is adaptable for PV arrays of any size. Overall, CS technique has showed its eminence in obtaining smoother output characteristics, better fill factor, power enhancement and increased energy savings.