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Power quality is improved by utilizing solar inverters in electrical grids and this study probes it. A combination of the solar power system with wind energy management using the multi-objective particle swarm optimization (CMOPSO) algorithm is employed in this system. Control calculations are based on Clark and reverse Clark transformations and facilitated by a phase-locked loop (PLL) circuit. STATCOM helps maintain voltage levels and mitigate power quality issues. Power quality (PQ) monitoring tracks voltage variations and noise. Conversely, the study addresses challenges in integrating renewables using the multi-objective multi-verse optimization (MOMVO) algorithm. MATLAB is used for control, monitoring, and analysis. Results show voltage distortion, but the proposed method achieves 92% higher efficiency, demonstrating its effectiveness. This validates the importance of photovoltaic (PV) technology for integrating renewable energy sources. [ABSTRACT FROM AUTHOR]

The paper investigates the state-of-the-art architecture of photovoltaic systems (PVS) by evaluating the performance of the developed maximum power point tracking (MPPT) algorithm of fuzzy particle swarm optimization (FPSO) for temperate continental latitudes. The material of the paper gives an evaluation of traditional MPPT algorithms in relation to the state-of-the-art FPSO algorithm. The study summarizes the problems of On-Grid PV systems and analyzes methods of solving them by combining them with hydrogen technologies. The paper summaries the experience of observations of climatic factors and solar resources on the example of the Russian Federation. Thus, in 2023, the average winter temperature exceeded the norm by 4.7 °C, and the average summer temperature exceeded the norm by 4.9 °C compared to 2022. The paper analyses the level of insolation, which increased by 0.03 kWh/m2 by regions of Russia for the period 2022–2023. The experimental part of the work was carried out at the solar power plant (SPP) «Kalmykskaya» with coordinates 53.422832 north latitude and 55.266895 east longitude. The watt-volt field characteristic of photovoltaic modules (PVM) connected to the inverter was obtained experimentally. When compared, the correlation coefficient between the experimental power (P) and voltage (U) of the panels was found to be higher than that of the ideal panels, 0.933 versus 0.914. The correlation coefficient between the ideal P(U) function and the experimental one is (−0.475). The data for calculating the coefficient of performance (COP) of the implemented MPPT algorithm was also obtained experimentally, which was about 98.7%. The reliability of the data used in the calculations was confirmed by two independent means of measurement, the difference of the obtained results was less than 1%. In the last part of the experiment of this study, the dependence of insolation in a given geographical point on the generated PV field power was evaluated. The correlation coefficient was 0.47, while the inverter output voltage was maintained in the nominal range of (600 ± 20%)V. Thus, the authors of the study experimentally proved the efficiency of using MPPT on FPSO in temperate continental climate with duration of sunshine T = 1850 h per year. The effectiveness of the FPSO algorithm under the conditions of inverter distance from the common point of the DC switching cabinet (DСCC) has been confirmed. The effectiveness of the MPPT algorithm based on FPSO under conditions of partial shading, increased cloud cover and increased air temperature is concluded. Using the description of the current architecture of On-Grid SPP, the authors draw attention to the impossibility of operation of such systems without the presence of voltage in the reference network. In addition, the impossibility of the system operation at the value of PVM power over 1500 kW and at the voltage of panels less than 900 V is noted. To modernize the existing PVS architecture, for the first time, the use of a DCCC and an inverter with implemented MPPT on the FPSO in combination with a hydrogen (H 2) production unit and nickel-hydrogen (Ni–H 2) batteries is proposed. The researchers propose that when the PVM field voltage is below 900 V and when the PVM field power exceeds 1500 kW, energy can be diverted to H2 generation or to charge Ni–H2 batteries via a DCCC controller. Such an architecture will improve the continuity and efficiency of the PVS, reduce the carbon footprint, and allow the PVS to be used as an industrial uninterruptible power supply (UPS). The authors see the lack of standardization of implemented projects based on the ESG principle as the main problem of alternative energy development. [ABSTRACT FROM AUTHOR]

This work proposes an efficient integration method of solar energy with industrial nonlinear loads, accounting for dynamic variations in solar power and load harmonic profiles. The involved dynamics necessitate that the solar interface front-end inverters be equipped to handle both harmonic distortions and active power injection characteristics simultaneously. In this work, an instantaneous load and source characteristic mapping is proposed for the solar-interfaced front-end inverter operated as a shunt active power filter cum active power injector in order to accommodate the dynamic variations of the source and load. As per requirement, to separate the load-demanded and switching harmonics, a new load network time constant-based passive filter design diverging from traditional passive filter design methods is demonstrated. Further, a comprehensive explanation of the current controller modeling methodology is elaborated, considering the essential bandwidth required for proficiently managing load-demanded harmonics in both grid injection and drawing modes of operation. Later, in grid injection mode, the influence of grid and system impedance interactions on the power quality is analyzed for weak grid scenarios to derive the requisite bandwidth conditions to ensure resilient power transfer. Subsequently, the experimental validation of the solar interfaced shunt active power filter (SISAPF) with active power injection capability is carried out in both grid power drawing and injection modes, demonstrating the effectiveness of the enhanced bandwidth in handling load-demanded harmonics and solar power dynamic variations.

Photovoltaic (PV) inverters are now supposed to provide additional supporting services with more reliability and efficiency. This paper presents three different control methods for generating reference current in a multifunctional, multilevel grid-tied PV inverter for harmonic, reactive, and unbalance compensation. These methods are the synchronous reference frame (SRF) theory (d-q), the instantaneous reactive power (IRP) theory (p-q), and the conservative power theory (CPT). As a result, the primary goal is to propose a low-cost multifunctional solar invert for distributed generation, with an appropriate prototype developed in the laboratory for experimental validation of various modes of operation. Demonstrated results show that the presented inverter is capable of providing various ancillary services with all three types of control. [ABSTRACT FROM AUTHOR]

Increasing the number of electrical vehicles determine an increasing of electrical vehicle chargers number too. The best situation is reach when the zero emission vehicles are charged with electrical energy produced by solar panels or another green energy. This paper presents a solar electric vehicle charger system with energy storage capabilities. The system should be considered as a combination of three systems: solar energy production system, energy storage system and electric vehicle charger system. One of the novelty of the system is that for energy storage is used a 2nd life Nissan Leaf electric vehicle battery. The paper gives information about, simulation and measurement of the annual solar energy production of the system, measurements results of the currents, voltages and powers of the system, and a distribution of the maximum daily energy production. [ABSTRACT FROM AUTHOR]

This paper compares the cost and efficiency of two inverter topologies for a 5-kW grid-connected solar inverter application: the Conventional H-Bridge Inverter (CHB) and the Cascaded H-Bridge Multilevel Inverter (CHBMLI). Emphasis is put on power switches and passive elements with a detailed study of the losses. Both designs respect the same constraints (cost, efficiency, and junction temperature of the transistors) to ensure a fair comparison between both topologies. The work highlights the important parameters when choosing the components (MOSFETs, capacitors, and magnetic cores for the inductors). The DC-link voltage ripple and the output AC current ripple are the key parameters for the design of the passive elements (capacitors and inductors). On top of that, the transistors MOSFETs are chosen, in both topologies, to limit the conduction losses (by selecting the R d s o n ) and the switching losses (by selecting the Q r r and d v / d t ). Real components are picked in order to make the comparison as complete as possible. Numerical simulations are performed using the MATLAB platform. All equations and parameters are provided. A CHBMLI prototype was built with eight independent H-Bridges to validate the proposed design with thermal and efficiency measurements. [ABSTRACT FROM AUTHOR]

Off-grid hybrid renewable energy systems represent the most modern and flexible solutions that can cover a wide range of energy efficiency needs for household consumers. In the current context, these systems must be taken into account by most household consumers, given the fact that the price of energy has increased. This paper proposes an experimental analysis of the behavior of such a system, in real operating conditions, considering two renewable energy sources, wind and photovoltaic sources, using an experimental stand. It can be considered a testing platform for hybrid energy production systems, in that the power installed in the two sources can be scaled up. The platform has the advantage of allowing the implementation of different load and wind curves through a programmable logic controller; in this way, it is possible to evaluate the degree of coverage of the energy consumption produced from renewable sources, in the north-east of Romania, in the Suceava County region. The experimental study also involves an analysis of the storage capacity in relation to the consumption and the electricity produced by the two renewable sources. In this regard, three scenarios differentiated by the state of charge (30%, 50% and 70%) have been established. The results indicate that, for each of the imposed scenarios, the energy required to cover consumption is produced by renewable energy sources (42%, 47% and 53%), to which the energy stored in batteries (39%, 28% and 18%) is added. [ABSTRACT FROM AUTHOR]

Renewable power capacity sets records annually, driven by solar photovoltaic power, which accounts for more than half of all renewable power expansion in 2021. In this sense, photovoltaic system design must be correctly defined before system installation to generate the maximum quantity of energy at the lowest possible cost. The proposed study analyses the oversizing of the solar array vs. the capacity of the solar inverter, seeking low clipping losses in the inverter. A real 4.2 kWp residential PV installation was modelled and validated using the software SAM and input data from different sources, such as a weather station for weather conditions, ESIOS for electricity rates, and FusionSolar to obtain energy data from the PV installation. Once data were validated through SAM, the DC to AC ratio was varied between 0.9 and 2.1. The azimuth and slope sensitivity analyses were performed regarding clipping inverter losses. Results have been evaluated through the energy generated and the discounted payback period, showing that, depending on the weather conditions, slope, and azimuth, among others, it is advisable to increase the DC to AC ratio to values between 1.63 and 1.87, implying low discounted payback periods of about 8 to 9 years. In addition, it was observed that inverter clipping losses significantly vary depending on the defined azimuth and slope. [ABSTRACT FROM AUTHOR]

During grid-connected operation, photovoltaic (PV) systems are usually operated to inject pre-set power to the grid. However, when the main grid is cut off from the PV system, standalone operation must be achieved while operating in voltage control mode. This brings new challenges for the control of PV inverters, i.e., voltage regulation and harmonic elimination. In this research, a wavelet-based fuzzy control for standalone operation of single-phase inverters is designed. The proposed controller regulates the output voltage by adjusting the fuzzy controller weights, which are operating in closed loop with the pulse width modulation generator. A hardware prototype of 1kWp standalone PV system is developed, and the proposed control method is evaluated on it. The proposed control achieves

In voltage source inverters (VSI), the output voltage is synthesized in an average sense using pulsewidth modulation (PWM) techniques. In space vector PWM techniques, the average realization of the space vector using volt-sec balance results in an instantaneous error that influences the dc bus current. The instantaneous ac load error voltage maps onto the dc bus derive the dc bus current ripple signatures that would be useful to size the dc capacitor. Exploiting concept of instantaneous mapping of ac error voltage onto the dc bus through power factor axis coordinates, in this work, the unprecedented dc ripple voltage computational method is presented. The established synchronous power factor reference frame ensures accurate mapping of ac error voltage onto the dc bus and makes the computational method independent of sensing actual ac load current unlike conventional methods. With the eliminated actual load current dependence, the proposed model can predict the minimum dc voltage ripple yield switching sequence for VSIs at different loading conditions. The efficacy of the proposed model in terms of optimum switching sequence elicitation is demonstrated on the dual inverter configuration experimentally considering the inflated switching stress due to two inverter's switching. [ABSTRACT FROM AUTHOR]

At present, the single stage inverters are popular in integrating large-scale solar farms with distribution networks that demand higher dc bus voltage. The elevated dc potentials would degrade the reliability of the solar panels and inverter modules. In this work, the multiboost solar inverter topologies of three variants are presented for grid-connected applications. Since the proposed topologies aim to achieve higher voltage boost at ac side with reduced dc bus potential, it is required to use asynchronous switching strategies, unlike parallel inverter configurations. Although the proposed topologies are advantageous in-terms of improved reliability of solar panels and inverter modules, but instantaneous characteristic impedance imbalance due to asynchronous switching provokes circulating current within the inverter modules. Since the circulating current is undesirable concerning power quality and thermal aspects, in this work, the method of instantaneous impedance balance is ensured with the specially designed switching algorithm for proposed topologies. The eliminated instantaneous circulating current provides the flexibility of operating all inverter modules with the common dc bus. The proposed high gain boost configurations and switching methodologies are demonstrated on hardware prototype by pumping 2.4-kW power to the grid. [ABSTRACT FROM AUTHOR]

In this article, a new topology for a grid-connected solar photovoltaic inverter for the direct connection to the medium-voltage grid is proposed. This topology employs an LLC resonant converter with a high-frequency (HF) isolation transformer in the dc–dc stage. The output of the dc–dc stage is a rectified sine wave voltage and current at the line frequency. An unfolder inverter interfaces between this dc stage and the grid. A combined phase-shift and frequency control method is used to control the LLC resonant converter. The phase-shift angle and switching frequency values of the LLC resonant converter are regulated to track the reference current signal for the whole operation range. The Lagrange multiplier method is applied to find the optimal trajectory to calculate the optimal phase-shift angle and switching frequency pairs for any operation condition by considering power converter and HF transformer losses to achieve the highest efficiency at a varying current. The transformer leakage and magnetization inductances are properly designed to provide a zero-voltage switching (ZVS) for a wide operation area, and additional resonant inductor requirement is removed. The LLC converter operates in a ZVS region except in a narrow band around the zero-current crossings of the inverter output. Using an HF transformer in the LLC resonant converter, a bulky line frequency transformer requirement is eliminated, and thus, a more compact and efficient design is obtained. The proposed topology is validated by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

Electromagnetic interference in power converters is a crucial problem for circuit designers. Electromagnetically compliant converter design is required for the safety of an operation. A novel filter design approach considering ground leakage current, different winding styles for common mode choke, tolerance of filter capacitor is proposed in this study to solve the electromagnetic interference problem. In the study, electromagnetic compatibility issue is investigated for a 25 kW, 15 kHz switching frequency, three-phase/level T-type grid-connected solar inverter. The test setup is installed based on EN55011 standard, and the interferences emitted by the inverter to the grid through conduction are measured. Then, a filter design is made to prevent these interferences from being transmitted to the grid. After the filter is designed and engaged, the measurements are repeated. So, the noise attenuation of the EMI filter is verified experimentally. Experiences obtained from the hardware modification in the EMI filter, which is designed for an industrial solar inverter, have been discussed. It is observed that the result of conducted emission measurement is within the limits of the EN55011 Class B standard.

In this work, a new series solar inverter configuration is proposed to share the power in terms of voltage, unlike parallel inverter configurations. In a single-stage parallel inverter, elevated dc potential and circulating current due to common mode voltage (CMV) would degrade the solar inverter’s life. The proposed topology eases the stress on the dc bus and protects the solar inverter from the issues associated with elevated dc potential (potential induced degradation effect, switch operating voltage stress, etc.). The inherent boosting capability of the proposed series inverter with two modular inverters is demonstrated through two switching algorithms. In the first switching algorithm, the switching combinations are devised to yield the maximum voltage across the load. The second switching algorithm demonstrates the method of eliminating CMV by choosing the appropriate switching combination of two inverters. The eliminated instantaneous CMV would give the provision of operating proposed topology with common dc bus along with the flexibility of dc bus grounding. For the proposed configuration with devised switching techniques, the closed-loop controller is designed by computing the plant’s equivalent characteristic impedance using a state-space model. The effectiveness of the proposed configuration, along with the closed-loop control, is validated through hardware. [ABSTRACT FROM AUTHOR]

Energy efficiency is a topic with many publications related to resource exploitation at a local scale; via well-performed energy management, substantial environmental and economic benefits can be achieved. In this article, the models used to forecast the photovoltaic power yield in two distinct facilities are described. These facilities are part of the same production plant, which makes use of different heterogeneous resources (carbon dioxide, water, thermal energy, and electricity) and has already been analyzed in a problem that consists in finding the set of variables that minimize the operation cost. In order to predict the power production for both photovoltaic fields, the expressions for radiation on sloped surfaces and the equivalent circuit for solar cells are employed, and the inverters and wiretransmission loss effects are considered. Furthermore, their integration within a generalpurpose modeling framework for energy hubs is demonstrated. The comparison between validation results and production real data shows that despite the slight overestimation of the energy yield, the models are suitable to forecast the production of both facilities with a suitable accuracy, as the R2 coefficients of both facilities lie between 0.95 and 0.96. [ABSTRACT FROM AUTHOR]

Off-grid hybrid renewable energy systems represent the most modern and flexible solutions that can cover a wide range of energy efficiency needs for household consumers. In the current context, these systems must be taken into account by most household consumers, given the fact that the price of energy has increased. This paper proposes an experimental analysis of the behavior of such a system, in real operating conditions, considering two renewable energy sources, wind and photovoltaic sources, using an experimental stand. It can be considered a testing platform for hybrid energy production systems, in that the power installed in the two sources can be scaled up. The platform has the advantage of allowing the implementation of different load and wind curves through a programmable logic controller; in this way, it is possible to evaluate the degree of coverage of the energy consumption produced from renewable sources, in the north-east of Romania, in the Suceava County region. The experimental study also involves an analysis of the storage capacity in relation to the consumption and the electricity produced by the two renewable sources. In this regard, three scenarios differentiated by the state of charge (30%, 50% and 70%) have been established. The results indicate that, for each of the imposed scenarios, the energy required to cover consumption is produced by renewable energy sources (42%, 47% and 53%), to which the energy stored in batteries (39%, 28% and 18%) is added.

Summary: Identifying maximum penetration level (MPL) of Solar Photo‐Voltaic Generation (SPVG) in the distribution system is crucial for system planners and network operators to keep the system parameters within the acceptable limits. This paper provides a systematic and extensive procedure for evaluation of MPL of SPVG and its enhancement methods in distribution systems. More importantly, it illustrates a novel algorithm for affixing the penetration cap of Solar PV. The methodology initially derives a new stability index for locating SPVGs in the system, including both active and reactive power support from SPVGs. The study shows the utility of redefining MPL of SPVGs by considering the reactive power injection through solar inverters also. Deviating from the practice of considering the conventional constraints of voltage rise and maximum loading for MPL estimation, the paper considers loss minimization as the major constraint. The algorithm has potential to identify distributed integration scenario of SPVGs compared to the limited number of placements in the extant algorithms. This paper provides a novel algorithm to evaluate of maximum penetration level (MPL) of solar photo voltaic generation (SPVG) and its enhancement methods in distribution systems. The utility of redefining the MPL of SPVG by considering the reactive power injection through solar inverter is illustrated. The algorithm has distinct advantages over the extant algorithms in identifying a distributed integration scenario. [ABSTRACT FROM AUTHOR]

The existing method for evaluating the derating characteristics is generally carried out with the use of a thermal cyclic chamber based on manufacturer requirements as there are no international standards pertaining to this characteristics test. This paper proposes an alternative test method which is developed for manufacturers and test laboratories across the world which can easily be adopted because of its advantages like low cost in terms of investment, practicality, accuracy and less time-consuming. The proposed alternate method for the temperature derating test is validated by carrying out the test on a three-phase 60 kW grid tie solar PV inverter with input DC MPPT voltage of 850 V. The experimental analysis and results show that during the power- temperature derating process, the variations in input DC voltage, output AC voltage, frequency, power factor, and voltage harmonics are constant. The variations were observed in the output AC current and input DC current showed a similar pattern by having maximum value during maximum continuous power delivery period i.e. 66 kW active power output and starts decreasing to 43 kW till the inverter tripped. It is concluded that the temperature difference (ΔT) between the external ambient air temperature and the internal ambient air temperature plays a major role in the power-temperature derating process of an inverter. [ABSTRACT FROM AUTHOR]

This article describes an example of a solar inverter design based on the quasi-Z-source network taking into account multi-objective optimization. An overview of the solar inverter market is provided. Based on this overview, the specification of the most important parameters of commercial solutions is derived. The target efficiency profile and operation range are selected as the main criteria for the design of a competitive solution. The theoretical losses model is designed for preliminary estimation of efficiency profile at any operation point. Optimal switching frequency range is defined. Active and passive components are selected according to the defined efficiency profile and the switching frequency range. The experimental setup including a pre-industrial prototype is built and tested. Experimental results demonstrate the performance of the solar inverter with different photovoltaic string profiles. Finally, the results and feasibility in the commercial application are discussed, and conclusions are drawn. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) systems are becoming more vulnerable to cyber threats. In response to this emerging concern, developing cyber-secure power electronics converters has received increased attention from the IEEE Power Electronics Society that recently launched a cyber-physical-security initiative. This letter proposes a deep sequence learning based diagnosis solution for data integrity attacks on PV systems in smart grids, including dc–dc and dc–ac converters. The multilayer long short-term memory networks are used to leverage time-series electric waveform data from current and voltage sensors in PV systems. The proposed method has been evaluated in a PV smart grid benchmark model with extensive quantitative analysis. For comparison, we have evaluated classic data-driven methods, including K-nearest neighbor, decision tree, support vector machine, artificial neural network, and convolutional neural network. Comparison results verify performances of the proposed method for detection and diagnosis of various data integrity attacks on PV systems. [ABSTRACT FROM AUTHOR]

The quality of power is always a concern for the high penetration of a grid-connected solar photovoltaic (PV) system due to the variation in solar irradiation and the temperature change of solar output, which in turn varies the fundamental component of power delivered to the grid. A solar source requires an inverter interface to supply the AC load as well as for the grid interconnection. Any reduction in the fundamental component generated by solar PV at a lower irradiation level or at high- temperature results in increasing %THD at the output of inverter for a given fixed switching frequency since harmonics due to PWM technique is comparable with the fundamental component. The selection of high-fixed-switching-frequency PWM reduces harmonics but increases the stress on switches and switching losses. It also suffers from issues of harmonics at carrier frequency and its sideband at multiples of switching frequency that causes acoustic noise and EMI. The random frequency PWM (Random PWM) method overcomes these issues presented by the fixed-frequency PWM method. However, a wide band of Random PWM makes the inverter filter design difficult and causes resonance in the distribution system. In addition, asymmetry in the carrier wave introduces even-order harmonics in the line current. Hence, this paper proposes a narrowband random frequency PWM method to reduce sideband harmonics, lower-order harmonics, even-order harmonics and a total harmonic distortion (THD) for a solar-based grid-connected inverter. Simulation results present a satisfactory performance of the proposed control technique for a steady-state and transient results. Experimental validation of the same is carried out on the OPAL-RT OP4500-based laboratory prototype of a 2-kVA inverter which depicts reduction in harmonics and hence improvement in power quality. [ABSTRACT FROM AUTHOR]

Inverter-based solar generation can cause load rejection overvoltage when the connected distribution circuit is islanded from the utility grid. The load rejection overvoltage presents electric stress on utility equipment, metering devices, and customer equipment. This article investigates the load rejection overvoltage mechanism of utility-scale solar generation based on measurements collected by utility protective relays. The impact of solar inverter induced overvoltage on arresters and customer equipment is analyzed. [ABSTRACT FROM AUTHOR]

Transformerless inverters are prone to irregular voltage profiles, high harmonics and isolation problems while operating with photovoltaic systems and varying load conditions under stand-alone mode. The aim of the paper is to identify the drawbacks of transformerless inverters operating in stand-alone mode and to propose a new topology with improved performance and control. Further, an intelligent controller is designed to operate the proposed topology with various loads and varying load conditions. The developed controller achieves voltage regulation and low total harmonic distortion for the proposed topology when simulated under MATLAB/Simulink environment. Further, a laboratory prototype of the proposed inverter operating under stand-alone photovoltaic application is developed and operated with the developed control method. The proposed topology along with the developed controller achieves output voltage regulation and reduced THD under varying load conditions. The THD of the proposed system while operating with constant load is observed to be 1.8%, and for varying load condition, it is around 2.12%. Further, the efficiency and power loss of the system are calculated, and it is observed the system exhibits 98.5% efficiency. The achieved results are better when compared with existing work. [ABSTRACT FROM AUTHOR]

An ever-increasing interest on integrating solar power to utility grid exists due to wide use of renewable energy sources and distributed generation. The grid-connected solar inverters that are the key devices interfacing solar power plant with utility play crucial role in this situation. Although three-phase inverters were industry standard in large photovoltaic (PV) power plant applications, the microgrid regulations increased the use of single-phase inverters in residential power plants and grid interconnection. This paper presents a detailed review on single-phase grid-connected solar inverters in terms of their improvements in circuit topologies and control methods. Even though there are many reviews have been proposed in the current literature, this study provides a differentiating approach by focusing on novel circuit topologies and control methods of string and micro inverters. The single and multi-stage solar inverters are reviewed in terms of emerging DC-DC converter and unfolding inverter topologies while the novel control methods of both stages have been surveyed in a comprehensive manner. The isolated and transformerless circuit topologies have been investigated by reviewing experimental and commercial devices. The soft computing, evolutionary and swarm intelligence based algorithms have been summarized in MPPT methods section while current injection and grid-connection control methods of unfolding inverters stage have been presented with and without PLL architecture. There are many papers have been compared and listed in each section to provide further outcomes which is followed by a summarizing discussion section and conclusion. [ABSTRACT FROM AUTHOR]

1.5 kV dc link voltage has been a trend for the solar industry. Moving from 1 to 1.5 kV dc voltage can increase string length, enhance inverter conversion ability, increase array block sizes, and improve performance. Multilevel converters are the natural choices while control becomes more complicated. If a simple two-level converter is adopted, the 1.7 kV device may not be applicable considering the voltage derating for certain failure rate. Therefore, devices with higher blocking voltage should be considered. This paper reports for the first time the performance characterization of a 2.5 kV silicon carbide (SiC) mosfet. The potential application of this device for 1.5 kV solar inverter is also evaluated compared to the solutions with a 1.2 kV device. [ABSTRACT FROM AUTHOR]

Solar energy will be changed by climatic conditions. Photovoltaic solar power generation is very sensitive to shading effect. Output of solar PV cell will be lessen, when a small part of a solar PV array is shaded. For solar photovoltaic systems, energy storage such as batteries and fuel cells has attracted considerably and demand for solar photovoltaic systems with energy storage devices has increased. If solar photovoltaic systems become a constant source of energy, resulting in improvement in solar photovoltaic values as well as performance. This article outlines a new converter called reconfigurable solar converter (RSC) for photovoltaic (PV) cells, especially for utility-scale PV applications. This document also includes MATLAB simulation and its results analysis. The main concept of the new converter is to use a single stage three-phase solar inverter for the DC / AC and DC / DC processes described in this document. This converter solution is attractive for photovoltaic systems with battery backup applications because it reduces the number of conversion stages, thereby increasing efficiency and reducing cost, weight and size. This document is very important for applications that are used to interpret the performance characteristics of the proposed RSC. This document proposes a new topology for the RSC that allows the use of a higher battery voltage than photoelectric voltage. The RSC concept is applied in local consumer optical battery applications. A range of RSC operating modes is suggested for optimal home use. Automatic change between these operating modes is another objective of this document. [ABSTRACT FROM AUTHOR]

Renewable energy sources are becoming an ever-larger contributor to the power grid. These renewable energy sources depend upon the power electronic devices, specifically inverters, being essential for connecting Photovoltaic (PV) generation to the grid. However, the Electromagnetic Pulses (EMPs) caused by the high-altitude nuclear explosions can generate fast broad-band pulses with nanosecond rise time, potentially causing damage or destruction to electronic components. To assess the vulnerability of PV inverters to high-altitude EMPs, the port testing and Pulsed Current Injection (PCI) modeling schemes are proposed based on the port impedance analysis. Wide-band frequency measurements are achieved by fusing impedance results from three vector network analyzers. Then, a PCI model is used to simulate the induced response to EMP, with two typical immunity levels of EC5 and EC8 tested. The experiment successfully excites the induced voltage and current under EMP, where the voltage and current can reach 1500V/40A and 8000V/150Aunder EC5 andEC8, respectively. The port vulnerability analysis results demonstrate that only some ports can survive under EC5. To defend against the impact of EMP, three protection strategies are discussed. • A wide frequency-based port impedance testing scheme is implemented. • A PCI model is given to reveal the vulnerability of solar inverters under EMP. • The port vulnerability is evaluated through the spectrum and cumulative energy. [ABSTRACT FROM AUTHOR]

• To detect islanding, the 4th harmonic is injected into the output current. • A modified Goertzel filter is employed to measure the harmonics of voltage. • The method is robust to variation of load quality factor and resonant frequency. • The impact of reactive power on frequency after islanding is compensated. • The method is fast and detects islanding within two cycles of fundamental frequency. Islanding occurs when a utility-interactive distributed generator (DG) is disconnected from the utility grid and continues to supply power to local loads. This condition has several consequences including damage to the equipment and personnel safety risks. Therefore, it is required by utility interconnection standards for the DG to stop energizing local loads in the case of islanding. In this paper, an active islanding detection method (IDM) based on injecting a disturbance into the phase-locked loop (PLL) of a grid-connected photovoltaic (PV) inverter and monitoring the harmonic components of the point of common coupling (PCC) is proposed. A modified Goertzel algorithm is utilized to detect the injected harmonic which is effective for a wide range of load conditions in terms of load quality factor, resonant frequency, and reactive power. The simulation results in MATLAB/Simulink show that the proposed technique is fast with minimum side effects on power quality features such as output current total harmonic distortion (THD). This method is implemented on a single phase 5 kW grid-tied PV inverter and is tested experimentally. The experimental results verify that the proposed technique is fast with zero non-detection zone (NDZ) which is effective for a variety of load conditions. [ABSTRACT FROM AUTHOR]