Search

• Introducing a new hybrid cascaded network structure for solar power generation forecasting. • Proposing the MRIG feature selection technique to enhance the forecasting performance. • Implement a deep learning time series prediction model combined of LSTM, NARX, ELM, MRIG methods. • Using the Wavelet Transform module eliminate fluctuation behaviors solar power generation time series. • Validating the performance of the proposed model for short term solar power generation forecasting by a real data sets from Iran. Today, renewable energies have a key role in sustainable and clean power generation. On the other hand, solar energy is available in most regions in developing economies. Therefore, photovoltaic power forecasting is crucial for low-carbon power operation, planning, and trading. In this paper, the proposed hybrid cascaded forecasters network model combines LSTM, NARX, ELM, MRIG feature selection, and WT techniques, enabling accurate Solar Power Generation Forecasting (SPGF) for the next 24 h. By integrating these diverse models, the hybrid approach capitalizes on the strengths of each model and compensates for their weaknesses. This synergy significantly enhances the efficiency and accuracy of the forecasting method, leading to improved SPGF performance. The results of day-ahead SPGF for this case study demonstrate the hybrid model's impressive accuracy. For instance, the average prediction error for SPGF of the Mahan PV power plant resulted in a MAPE of 4.7213%, MAE of 0.0100 MW, and RMSE of 0.0198 MW. [ABSTRACT FROM AUTHOR]

Solar-driven biomass gasification is a promising technology to improve the utilization efficiency of solar energy and biomass, which also enhances the thermochemical storage and the subsequent stable utilization. Whereas, the intermittence of solar energy deteriorates the stability and continuity of the thermochemical reaction process, which limits the efficient conversion of the reaction. In this regard, this work proposes a new solar-driven biomass gasification technology based on solid particle heat carrier. Different from the direct solar-driven gasification, solid particles are performed as medium to receive the concentrated solar radiation energy and transfer energy to biomass feedstocks. In addition, the combined power generation scenario is adopted to evaluate the thermodynamics and economics of the technology. The integration of solid particle heat storage, the system dispatch and stable operation will be further enhanced. Results show that under the optimal condition, the system maximum thermal and exergy efficiencies are increased by 12.94% and 12.51%, respectively. Considering the system off-design operation, with the evaluated typical periods of four seasons, the averaged power generation efficiency is increased by 5.16%, with the highest efficiency improvement of 9.41% occurring in the typical winter days. With the change of receiver price and biomass price, the maximum decline of levelized cost of electricity reaches to 17.6%, which presents the favorable economic benefits. As a new solar thermochemical technology, this technology exhibits competitive characteristics, significantly improving the utilization efficiency of solar and biomass energy. • New type of solar driven biomass gasification technology by solid particles is proposed. • The combined power generation scenario is adopted to evaluate the technology. • The optimal operating condition of the system are obtained by genetic algorithm. • The dynamic operating characteristics and economic potential of the system are evaluated. [ABSTRACT FROM AUTHOR]

The objective of this study is to derive a design methodology for a zero-energy building considering the energy production and consumption of the building. In order to establish the design methodology, various factors affecting the energy production and consumption of the building are derived, and the effect of the heat transmission rate, the surface to volume ratio (S/V ratio), the location and the orientation of the building are analyzed by simulation method. As a result, the S/V ratio and the heat transmission rate are the most important factors in the central region of Korea where consumes large amounts of heating and cooling energy. This is because the final energy consumption varies depending on the heat loss through the envelope. It was confirmed that solar power generation is the most important factor in the southern regions of Korea where the energy consumption is relatively small. The final energy consumption varies depending on the solar power generation in these areas. Therefore, when designing a zero-energy building, the zero-energy of the building can be achieved by using the design methodology established in this study.

The conveyance of steel-plates is one of the potential uses of the magnetic levitation technology in industry. How¬ever, the electromagnetic levitation systems inherently show non¬linear feature and are unstable without an active control. Well-known U-shaped or E-shaped electromagnets cannot provide redundant levitation with multiple degrees of freedom. In this paper, to achieve the full redundant levitation of the steel plate, a quadruple configuration of U shaped electromagnets has been proposed. To resolve the issue of instability and attain more robust levitation, a centralized control algorithm based on a modified PID controller (I PD) is designed for each degree of freedom by using the Manabe canonical polynomial technique. The model of the system is carried out using electromechanical energy conversion princi¬ples and verified by 3-D FEM analysis. An experimental bench is built up to test the system performance under trajectory tracking and external disturbance excitation. The results confirm the effectiveness of the proposed system and the control approach to obtain a full redundant levitation even in case of disturbances. The paper demonstrates the feasibility of the con¬veyance of steel plates by using the quadruple configuration of U-shaped electromagnets and shows the merits of I-PD controller both in stabilization and increased robust levitation.

Photovoltaic (PV) system has a great potential and it is installed more when compared with other renewable energy sources nowadays. However, the PV system cannot perform optimally due to its solid reliance on climate conditions. Due to this dependency, PV system does not operate at its maximum power point (MPP). Many MPP tracking methods have been proposed for this purpose. One of these is the Perturb and Observe Method (P&O) which is the most famous due to its simplicity, less cost and fast track. But it deviates from MPP in continuously changing weather conditions, especially in rapidly changing irradiance conditions. A new Maximum Power Point Tracking (MPPT) method, Tetra Point Perturb and Observe (TPPO), has been proposed to improve PV system performance in changing irradiance conditions and the effects on characteristic curves of PV array module due to varying irradiance are delineated. The Proposed MPPT method has shown better results in increasing the efficiency of a PV system.

This paper studies the environmental impact of two different forms of solar power generation in Thailand - that of multicrystalline silicon solar cells, and that of thin film amorphous silicon solar cells. It takes as its study two of the largest solar cell power plants of their kind in Thailand; a multicrystalline silicon plant in the north (generating 90 MW) and a thin film amorphous silicon plant in the centre (generating 55 MW). The Life Cycle Assessment tool (LCA) was used to assess the environmental impact of each stage of the process, from the manufacture of the cells, through to their transportation, installation and eventual recycling. The functional unit of the study was the generation of 1 kWh of power transmitted and distributed by the Electricity Generating Authority of Thailand (EGAT) and Provincial Electricity Authority (PEA). The environmental impact results were calculated in terms of eco-points (Pt) per functional unit of 1 kWh. The characterised data for 1 kWh of solar power generation was then compared with data for 1 kWh of combined cycle and thermal power generation (both in Thailand), using the same set of characterisation factors. After analyzing the results, both forms of solar power energy generation were found to impact upon the studied categories of Human Health, Ecosystem Quality and Resource Depletion, whilst also highlighting the importance of the solar cell module recycling process in decreasing the overall environmental impact. When the two solar cell technologies were compared, the overall impact of the multicrystalline silicon solar cell was found to be higher than that of the thin film amorphous silicon solar cell. Furthermore, when assessing the overall impact against non-renewable power generating technologies such as combined cycle and thermal power generation, the thin film amorphous silicon solar cells were found to have the lowest environmental impact of all technologies studied.

Due to the environmental burden, natural hazard and energy dilemma in Japan, renewable energy integration has become a key technology in the development of power systems and there has been significant increase in the use of wind and solar power generation. With the development of technologies and free fuel source offering, renewable energy power has been widely used in power system all over the world. On the other hand, because of diversification of generation operating in power system, it becomes more and more important to ensure the security and stability of power system in terms of supply–demand balance with a proper frequency range, to this end, balancing market has been developed in some European countries and regions in order to purchase the balancing power capacity and energy efficiently. In Japan, with the feed-in tariff policy spreading from 2012, it becomes a possibility that renewable energy balancing power participating in balancing market which will be newly established in 2020.

Technology related to solar power as a renewable energy resource has increased in recent years. However, in Japan, forestland has been converted into mega-solar power plants with more than 1 MW photovoltaic capacity and such conversions raise significant concerns as they degrade forest ecosystem services. In this study, the profit and power supplies generated by a mega-solar power plant and a cedar (Cryptomeria japonica) plantation were evaluated. The profit for the cedar plantation was estimated from saw log and wood chip production, and its power supply was estimated from wood chip production alone. These figures were based on an optimal forest management strategy that was generated using a dynamic programming model. In this numerical simulation, it was found that the power supply from the mega-solar power plant was 50–150 times more than that from the cedar plantation. Regarding profit, it was found that the simulated mega-solar power plant provided NPV (net present value) of 8.5–90.6 MM JPY (Japanese Yen)/1–3 ha (0.1–3.0 MM JPY/ha/year), while the forest management simulation generated an NPV of 29,863 JPY/ha/year (for one timber rotation) and SEV (soil expectation value) of 3.6 MM JPY/ha at most. To avoid the conversion of forests into mega-solar power plants, this difference provides a basis for the cost of maintaining forests for ecosystem services and potential economic incentives.

This paper discusses the design and application of solar photovoltaics (PV) under aerospace conditions. The application of solar PV that is addressed is the Power Distribution Unit (PDU) for the Canadian Space Agency’s (CSA) stratospheric balloon (STRATOS) program. The PDU utilizes four 1 kWh Battery Unit (BUs) that have been sized with volume and weight restrictions in mind. Without the capacity to provide enough energy to support multi-day missions, they are thus supplemented by the solar power generation subsystem presented in this paper. The power generation sub-system includes a bespoke solar panel design and a centralized Maximum Power Point Tracking (MPPT) power conversion unit to maximize the power output of solar panels. The centralized unit can accommodate up to eight solar panels, each consisting of nine individual C60 SunPower solar cells. The centralized MPPT unit consists of two MPPT controllers, each controller supporting up to four solar panels. The MPPT unit is modular and can be easily integrated to the CSA’s existing intelligent Battery Management System (BMS).

Several control strategies have been proposed with the aim to get a desired behavior in the power converter variables. The most employed control techniques are linear control, nonlinear control based on linear and nonlinear feedback, and predictive control. The controllers associated with linear and nonlinear algorithms usually have a fixed switching frequency, featuring a defined spectrum given by the pulse width modulation (PWM) or space vector modulation (SVM) time period. On the other hand, finite set model predictive control (FS-MPC) is known to present a variable switching frequency that results too high for high power applications, increasing losses, reducing the switches lifetime and, therefore, limiting its application. This paper proposes a predictive control approach using a very low sampling frequency, allowing the use of predictive control in high power applications. The proposed method is straightforward to understand, is simple to implement, and can be computed with off-the-shelf digital systems. The main advantage of the proposed control algorithm comes from the combination of the model predictive control and the SVM technique, drawing the principal benefits of both methods. The provided experimental results are satisfactory, displaying the nature of space vector-based schemes but at the same time the fast response as expected in predictive control.

Highlights • Grid-connected PV system with primary frequency response capabilities. • The De-load margin is optimally selected without forfeiting PV generation. • A realistic network is considered by incorporating various system nonlinearities. • Frequency responsive PV model is achieved via the primary response controller. Abstract The share of photovoltaic sources in power supply networks is increasing during the past few decades. This has resulted in the reduction of rotational inertia of the power system and thereby affecting the system frequency regulation capability. In view of this, there is an increasing need for PV also participating in frequency regulation of the system. In this paper, a power control strategy of PV has been formulated for frequency regulation without any energy storage system. The proposed controller derives droop and inertial response from the PV by operating it at a reduced level of power reserve without forfeiting system stability and economic benefits. To assess the effectiveness of the proposed controller, an IEEE 14-bus test system is considered and load disturbances were investigated through simulation studies. The bus system is extended to a more realistic network by incorporating different generating units and has also considered various non-linearities such as Generation Rate Constraint, Governor Dead Band, and delay in Area Control Error signal. The results show that the combined control of droop and inertial response from PV system contributes in a better way for frequency control. The superiority of the proposed controller has been demonstrated by comparing the results with the recently published frequency control regulation with PV. It is observed from the simulation results that the proposed control provides a better response. Also, sensitivity analysis is performed to investigate the robustness of the controller to variations in system parameters from nominal values. Finally, an economic analysis is carried out to study the prospect of PV participating in ancillary services. [ABSTRACT FROM AUTHOR]

A simple multiplier for the estimation of the maximum power yield of a solar panel may be realized with a pulsewidth modulator working as analog multiplier circuit. Though the output of the pulsewidth modulator multiplication is not proportional to the actual output power of the solar panel, it may be shown that its maximum follows the maximum of the power curve of the panel. The multiplier allows a complete analog implementation of the maximum power point tracker of the panel thus keeping the simplicity needed in robust electronic systems. This paper presents the working principle of the maximum power point regulator, its design procedure, and a practical implementation for a low power solar panel, 7.1 V and 487 mA, used in small satellite platform applications. [ABSTRACT FROM AUTHOR]

Globally, almost all PV installations are deployed with maximum power point tracking (MPPT) technique to extract the maximum available power output. However, in the case of an electrically faulty PV arrays, the MPPT operation rapidly optimizes the fault current magnitudes to significantly low values that enforce line-line (LL) and line-ground (LG) faults to remain undetected in the system for longer time periods. Therefore, this paper proposes a sensorless, simple tracking technology to detect any LL/LG faults in a PV array by utilizing MPPT itself. The proposed technique exploits the uniqueness of the rightmost power peak (RPP) in the output characteristics of the PV array to detect LL/LG faults. For implementation, the globally used perturb & observe (P&O) MPPT algorithm is deployed to track the RPP. Experimental results reveal that the proposed methodology is well efficient to detect any LL/LG faults in PV arrays irrespective of the level of mismatch, system type, and the system rating. In addition, faults occurring in low irradiance levels and partial shading conditions (PSCs) can also be detected with incredible accuracy. Furthermore, the proposed technique is proficient to distinguish LL/LG faults from PSCs and temperature variations of a PV array in real-time environment. The merits of the proposed concept are its scalability, simplicity, and practical fitness. [ABSTRACT FROM AUTHOR]

The Integration of renewable energy resources suffers from two fundamental issues: variability, and uncertainty of power output. These issues hinder the integration of renewable resources with the existing grid. This paper addresses these issues and proposes a new methodology to minimize the impact of intermittency by offering an alternative approach for energy storage. The concept of value storage is introduced as an alternative to energy storage to replace the typical large-scale battery energy storage system. The concept refers to the storage of excess renewable energy as products from industrial loads instead of the energy itself which enables a demand side management technique to be applied, namely, load shifting for some industrial plants. A hybrid Photovoltaic-wind turbine generator PV-WTG and storage system is proposed to penetrate the existing electric grid, with significant cost savings by displacing the conventional energy generation in a fossil fuel-rich location. A size optimization based on differential system cost is formulated and solved by an enhanced genetic algorithm technique. Uncertainty impact studies were done by incorporating multiple scenarios and comprehensive sensitivity analysis. [ABSTRACT FROM AUTHOR]

Abstract Nowadays, utilizing solar energy for power production at high efficiency and in a cost-effective status is a challenging issue for power plant engineers. This challenge would be answered by considering several affecting parameters such as technical, economic, and environmental criteria. In this investigation, in order to provide an assessment for implementing solar power plants in the southeast of Iran, Sistan and Baluchistan province, a multi-criteria decision making (MCDM) approach is linked to a geographic information system (GIS). The MCDM approach is used to appraise the effective criteria for implementing solar power plants. The environment, orography, economic and climate are selected as the important criteria. Each criterion is assessed for the defined location of the investigation (Sistan and Baluchistan province) and in addition, GIS is employed to provide a geographical-graphical valuation to determine the most appropriate place for installing a large-scale solar power production plant. The solar systems considered in this study are photovoltaic (PV) collectors and concentrated solar power (CSP) generation plants (e.g. solar trough collectors). Technical and theoretical valuations are made to specify the amount of solar power which can be harnessed in Sistan and Baluchistan. In overall, it is demonstrated that this specific location in the southeast of Iran has the technical potential to provide 7,419 TWh/y and 8,758 TWh/y of solar electricity by installing CSP and PV technologies, respectively. Highlights • Integration of geographic information system and analytical hierarchy methods was developed to assess solar potential. • 4 criteria including environmental, economic, orography and climate are defined and nine alternatives with six restrictive. • The methods were applied in the theoretical and technical evaluation of photovoltaic and concentrated solar power. • 14% and 12% of selected area host the best suitability for photovoltaic and concentrated technologies. [ABSTRACT FROM AUTHOR]

The impact of photovoltaic distributed generation (PVDG) in the voltage sag indices of low-voltage distribution systems is assessed in this paper. A sensitivity study of these indices in relation to the penetration level of PVDG is performed considering the effect of the feeder sections loading on their failure rates. It is showed that, when this dependence is neglected, the indices are predicted with errors, especially for scenarios with large integration of PVDG. This study was performed using clustering techniques to model the uncertainty of solar irradiation, and the state enumeration method (SEM) is used to evaluate voltage sags indices. The results obtained by the clustering method and SEM were compared with those obtained with Monte Carlo Simulation based on the beta probability density function (pdf) model for solar irradiation. This comparison showed that the clustering model can obtain indices with precision comparable to those obtained with the beta pdf model, but with a significant reduction in CPU time. [ABSTRACT FROM AUTHOR]

This paper researches the performance of a novel supercritical carbon dioxide (S-CO2) Brayton cycle and organic Rankine cycle (ORC) combined system with a theoretical solar radiation diurnal distribution. The new system supplies all solar energy to a S-CO2 Brayton cycle heater, where heat releasing from the S-CO2 cooler is stored in the thermal storage system which is supplied to the ORC. Therefore, solar energy is kept at a high temperature, while at the same time the thermal storage system temperature is low. This paper builds a simple solar radiation diurnal distribution model. The maximum continuous working time, mass of thermal storage material, and parameter variations of the two cycles are simulated with the solar radiation diurnal distribution model. 10 organic fluids and 5 representative thermal storage materials are compared in this paper, with the mass and volume of these materials being shown. The longer the continuous working time is, the lower the system thermal efficiency is. The maximum continuous working time can reach 19.1 hours if the system provides a constant power output. At the same time, the system efficiency can be kept above 38% for most fluids. [ABSTRACT FROM AUTHOR]

Short-term prediction of multivariate dynamical processes evolving over time when data are partially observable is a challenging task. The power from solar resources has reached grid parity and must be predicted based on real-time observations available up to the current time step to ensure efficient power systems operation. However, solar data in the form of a time series generated by a network of sensors are not always available. Invisi-ble solar sites and communication failure are two causes that leave the energy management data acquisition system with an incomplete solar time series, thus leading to inaccurate forecasts. This paper addresses the impact of partially observable measurements on short-term solar power prediction. We present a low-rank tensor learning scheme to predict six-hour-ahead solar power generation. We use actual multivariate spatio-temporal National Renewable Energy Laboratory solar data in the state of Kansas presented in the form of tensors along with a photovoltaic power conversion model. A design of experiments experimental framework has been proposed to evaluate single and joint effects of spatio-temporal partially observable sites and the regulating parameters on forecasting accuracy. Numerical results show the capability of the framework to uncover detailed insight into the forecasting model behavior. [ABSTRACT FROM AUTHOR]

Commercial-scale, grid-connected battery energy storage system (BESS) typically operates on price-driven or peak shaving charging cycles. However, when installed in a distribution grid next to medium or large-scale photovoltaic (PV) generation, BESS can also play an important role in voltage regulation processes. Therefore, this paper proposes a new, model-driven controller which incorporates BESS into a voltage regulation scheme in order to counteract voltage variation caused by PV power fluctuations. In addition, the method optimizes control efforts and coordinates regulation actions of BESS and remaining grid devices. The algorithm was tested on a model implemented in the real-time digital simulator of a real grid equipped with a medium-scale BESS (0.6 MW/0.76 MWh) and 3.15 MWp of PV generation. As a result, the developed controller managed to regulate grid voltages quickly and without a significant influence on BESS charging cycle. The algorithm can be applied to distribution grids which already suffer from voltage fluctuations or to enhance PV generation in weak feeders by providing much faster and precise voltage control. [ABSTRACT FROM AUTHOR]

Under voltage faults, grid-tied photovoltaic inverters should remain connected to the grid according to fault ride-through requirements. Moreover, it is a desirable characteristic to keep the power injected to grid constant during the fault. This paper explores a control strategy to regulate the active and reactive powers delivered by a single-stage photovoltaic generation system to the grid during asymmetrical voltage faults. The reference for the active power is obtained from a maximum power point tracking algorithm, whereas the reference for the reactive power can be set freely if the zero-sequence voltage is null; otherwise, it will depend on the magnitude of the zero-sequence voltage and the active power reference. The power control loop generates the reference currents to be imposed by the grid-tied power inverter. These currents are regulated by a predictive controller. The proposed approach is simpler than other methods proposed in the literature. The performance of the control strategy presented is verified with an experimental laboratory setup where voltage sags and swells are considered. [ABSTRACT FROM AUTHOR]

The traditional electric grid is changing, being affected in all their fields by the technological advances, and moving to a new paradigm called smart grid. This is the reason for which different forms of incentives and different systems of energy commercialization for the distributed generation can be found; that added to the investment in research and development make that the destination of the world energy investments goes mostly to the renewable sources. Today, there are several renewable energy elements at different voltage levels of the grid. There are different pilot tests where different technologies and products are tested, which are presented daily by different manufacturers. In this work, an understudy microgrid is presented where different renewable sources are connected to the traditional grid, supporting like that the Argentinean objective of having 20% of renewable energy by the year 2025. In addition to the calculations made for the campus, as a pilot test, practical experiences are presented in the university's electricity laboratory by integrating renewable sources in the distribution network. We analyze the steady-state and short-circuit currents, which provide the different types of source to the network and how they affect distribution protection systems. The proposed micro-network consists of wind turbines and photovoltaic panels in different configurations distributed across the campus, where after analyzing the data obtained, better results than expected were yielded. [ABSTRACT FROM AUTHOR]

Abstract In order to realize a large-capacity stand-alone emergency power supply that enables highly reliable and high-quality power supply at the time of a large-scale natural disaster and enables effective use of solar power generation, we proposed an electric and hydrogen hybrid energy storage system (HESS). It is composed of an electric double-layer capacitor bank, fuel cell, electrolyzer, and hydrogen storage (buffer gas tank and metal hydride). In an emergency, this HESS is expected to supply power for loads together with photovoltaics panels for a long time. In usual time, it should not only cooperate with external electricity grids to convert unstable photovoltaic output power into reliable power supply, but also maintain sufficient stored energy in case of emergency. To realize the continuous operation of the HESS in both emergency and usual time, we proposed an electric double-layer capacitor's state-of-charge feedback control method and a hydrogen energy feedback control method, coordinating an energy management method based on Kalman filter algorithm. An experiment and a simulation demonstrated the operations of a 10-kW scale model HESS in emergency and usual time mode, respectively. The demonstrations verified the correct performance of the proposed HESS with the proposed control methods and enabled the continuous operation of the HESS. Highlights • Developed energy control methods in an electric and hydrogen energy storage system. • Enabled long-time continuous operation of the system by the energy control methods. • Verified system's operation as stand-alone emergency power supply by an experiment. • Verified the operation for effective on-grid PV power generation by a simulation. [ABSTRACT FROM AUTHOR]

An enhanced DC–DC converter is proposed in this paper, based on the combination of the Cuk and SEPIC converters, which is well-suited for solar photovoltaic (PV) applications. The converter uses only one switch (which is ground-referenced, so simple gate drive circuitry may be used), yet provides dual outputs in the form of a bipolar DC bus. The bipolar output from the DC–DC converter is able to send power to the grid via any inverter with a unipolar or bipolar DC input, and leakage currents can be eliminated if the latter type is used without using lossy DC capacitors in the load current loop. The proposed converter uses integrated magnetics cores to couple the input and output inductors, which significantly reduces the input current ripple and hence greatly improves the power extracted from the solar PV system. The design methodology along with simulation, experimental waveforms, and efficiency measurements of a 4-kW DC–DC converter are presented to prove the concept of the proposed converter. Furthermore, a 1-kW inverter is also developed to demonstrate the converter's grid-connection potential. [ABSTRACT FROM AUTHOR]

Home energy management systems (HEMSs) encourage participation of residential consumers into the demand response programs. This paper proposes a robust Conditional Value at Risk (CVaR) optimization approach for day ahead HEMS to reduce the effect of risk of real-time exposure to energy price and solar power generation uncertainties. Initially, the CVaR method is integrated with the two-point Estimation (2PE) analysis to approximate the solar power, modeled as Beta probability distribution function, in low computation effort compared to conventional Monte Carlo simulation (MCS) based CVaR approach. Then the optimization constraints are revised to their robust counterparts by accounting a certain amount of uncertainty in the energy prices from their nominal values. Unlike the previous literatures, the optimization problem is developed to minimize the risk value of the energy cost. Again to maximize the life of the plug-in electric vehicle (PEV) a pseudo cost function for the PEV battery degradation is proposed. The entire optimization portfolio is developed as a mixed integer linear programming for its easy execution. Simulation is demonstrated on a smart home, designed as an ac–dc microgrid, having practical appliance data sets, to prove the efficacy of the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes an improved second-order generalized integrator with frequency-locked loop (ISOGI-FLL) based control scheme for a grid-connected solar photovoltaic (PV) array fed voltage source converter (VSC) to mitigate the power quality problems. The steepest descent algorithm based maximum power point tracking is used to achieve the crest power from a solar PV array to improve solar power generation (SPG) into the grid as well as to maintain dc bus voltage of the VSC. The ISOGI-FLL-based control scheme is very effective for grid currents balancing and harmonics mitigation, at a variation of SPG and unity power factor operation. Simulated results are demonstrated using MATLAB/Simulink for load unbalancing and variation in solar insolation. The effectiveness of the proposed algorithm is demonstrated based on comparative performance with conventional algorithms. Test results of a developed prototype show satisfactory performance for different operating conditions like grid currents balancing, photovoltaic-distribution static compensator (PV-DSTATCOM) mode, and DSTATCOM-PV mode at variable solar insolation. Moreover, total harmonic distortions of grid voltages–currents are achieved within the limit of the IEEE-519 standard. [ABSTRACT FROM AUTHOR]

Abstract A fully integrated renewable energy atlas is presented which provides the wind and solar photo-voltaic (PV) power generation potential as well as cooling demand for Pakistan at a temporal resolution of 1-hr and spatial resolution of 14 × 14 km 2 . The proposed atlas uses weather based modelling for calculating renewable power generation time-series and the power-demand modelling is performed using real hourly electrical-load demand, conventional power generation and power consumption data for the year 2016. It has been found that Pakistan has much higher potential for the wind power generation than solar (PV) power generation and very good potential for the concentrated solar power. Furthermore, the optimum wind/solar power mix suggests that 95% of wind power generation and 5% of solar (PV) power generation leads to the least amount of power-shortfall. It is envisioned that the integration of renewable energy with cooling sector can be instrumental in overcoming Pakistan's electrical power-crisis. The current power-shortfall of 38.36 TW h can be resolved by installing rated wind and solar (PV) power generation capacity of 10.4 GW and 882 MW, respectively. Highlights • A fast and flexible high-resolution renewable energy atlas for Pakistan is presented. • Power-losses between the current power generation and consumption are almost 8%. • Power-shortfall of 38.36 TW h can be resolved with optimum wind/solar power mix of 95/5. • Geographical wind, solar PV power potential and cooling demand timeseries are calculated. • The significance of using weather-based modelling in energy system is shown. [ABSTRACT FROM AUTHOR]

This paper presents a dynamic power flow management system for a solar photovoltaic (PV) system employing a single-stage single-inductor-based dual-input/output dc–dc converter feeding standalone dc loads backed up by a rechargeable battery. A time-sharing voltage-mode control scheme has been proposed for power flow management between solar PV, a battery, and a standalone dc load, and it also maintains a constant dc load voltage and performs maximum power point tracking operation of solar PV. The implementation of the control scheme has been described in detail. The steady-state performance of the single-stage converter has been explained with the relevant analytical expressions derived along with the characteristics. A state-space average model was developed for simulating the transient behavior and validating the working of the system for step changes in the input solar PV power and the dc loads. A hardware prototype of the proposed system has been fabricated, and the proposed controller has been implemented using the dSPACE DS1103 real-time interface board. The working of the proposed scheme for different levels of input solar insolation and dc load power demand has been satisfactorily demonstrated, and the corresponding results are also provided. [ABSTRACT FROM AUTHOR]

Driving through many neighborhoods of Hawai'i, it is hard to miss the nearly ubiquitous rooftop solar photovoltaic (PV) systems that have popped up during the past eight years or so. Relatively high electricity costs associated with island grids, coupled with various incentives, have made it cost-effective to install solar over the last eight years, as evidenced by the PV-deployment chart in Figure 1. On the most populous island, O'ahu, the PV nameplate acgenerating capacity of 502 MW totals nearly half of the annual peak load for the entire island, which is 1.1 GW. Of that 502 MW of PVs, 54% is from private rooftop solar-nearly 50,000 residences or roughly one of every three single family homes. But Hawaiian Electric, the local utility, has no way to monitor or control the PV generation, even for most nonresidential systems. This means that on sunny days, up to approximately half of the PV generation is outside of the utility's control. This poses many challenges for utility planners and operators-challenges that Hawaiian Electric has been working diligently to address, along with various partners, notably the U.S. Department of Energy (DOE), the National Renewable Energy Laboratory (NREL), and its Energy System's Integration Facility (ESIF). This article describes how Hawaiian Electric has worked with engineers in NREL's Power Systems Engineering Center to improve the way its grid operates with very high levels of distributed PVs, largely by changing the way the PV inverters are operated. [ABSTRACT FROM AUTHOR]

The six articles in this special section focus on distributed energy resources (DERs). Since the first issue in this magazine on DER grid integration in the summer of 2009, DERs, specifically, solar PV-based systems, have evolved considerably to meet the needs of the power system from a planning and operations perspective. The result of this evolution is the theme of this issue: DERs play a major role in the power system. When relatively small numbers of PVs were first being installed, they were often showcases or demonstrations for the underlying technology, which was still quite expensive. The grid integration of these systems was a great research project, but many impacts we now see regularly simply did not exist at the earlier low-penetration levels. Now, nearly every distribution utility has experienced at least a few instances and challenges of DER integration within its service territory. [ABSTRACT FROM AUTHOR]

Rooftop solar energy, storage batteries, and electric vehicles are changing the way people use and produce electricity. These are among the growing set of technologies called distributed energy resources (DERs) because they are typically connected to the utility at the medium-voltage distribution system. In general, the utility distribution system connects substations to homes and businesses. The effect of DE Rs on operating the power grid has been dramatic and exciting, and they provide both challenges and benefits to the entire grid: spanning utilization, distribution, and transmission voltage ranges. The zero-carbon resources among the broader family of DE Rs are critical in complying with state and federal energy policies. This, in turn, has required grid operators, utilities, regulators, consumer advocates, and lawmakers to reach out across traditional domains to engage in the robust dialog and coordination needed to integrate distribution-level resources to the larger high-voltage grid and the networked bulk power systems (BPSs). [ABSTRACT FROM AUTHOR]

The uncertainty arising from high levels of solar photovoltaic (PV) penetration can have a substantial impact on power system operation. Therefore, there is a need to develop models capable of representing PV generation in a rigorous manner. This paper introduces a novel transformation-based methodology to generate stochastic solar area power forecast scenarios; easy to apply to new locations. We present a simulation study comparing day-ahead solar forecast errors covering regions with different geographical sizes, total installed capacities, and climatic characteristics. The results show that our model can capture the spatio-temporal properties and match the long-term statistical properties of actual data. Hence, it can be used to characterize the PV input uncertainty in power system studies. [ABSTRACT FROM AUTHOR]

In this letter, we propose to integrate a microstrip antenna with commercial solar cells for CubeSat applications where there is a small surface area available for a combination of antennas and solar cells. By placing the radiator for an aperture-coupled patch antenna under the solar cells, it is shown that a directional antenna system can be incorporated into a CubeSat without significant impact to the performance of the antenna. Considering stringent size restrictions involved in CubeSat designs, the proposed solution provides significant overall system size reduction and design flexibility. The solar cell integrated antenna is designed for operation in the 2.2–2.3 GHz space-to-Earth downlink band. Circular polarization is achieved by feeding two 90° rotated patches with a 90° phase offset signal. The results show very promising performance. [ABSTRACT FROM AUTHOR]

Dispatchable solar power generation is one of the key building blocks for the 21st century grid, while the nuclear and fossil industries continue to demand improved efficiencies to remain competitive. [...]

Photovoltaic (PV) systems need measurements of incident solar irradiance and PV surface temperature for performance analysis and monitoring purposes. Ground-based network sensor measurement is preferred in many near real-time operations such as forecasting and photovoltaic (PV) performance evaluation on the ground. Hence, this study proposed a Fuzzy compensation scheme for temperature and solar irradiance wireless sensor network (WSN) measurement on stand-alone solar photovoltaic (PV) system to improve the sensor measurement. The WSN installation through an Internet of Things (IoT) platform for solar irradiance and PV surface temperature measurement was fabricated. The simulation for the solar irradiance Fuzzy Logic compensation (SIFLC) scheme and Temperature Fuzzy Logic compensation (TFLC) scheme was conducted using Matlab/Simulink. The simulation result identified that the scheme was used to compensate for the error temperature and solar irradiance sensor measurements over a variation temperature and solar irradiance range from 20 to 60 °C and from zero up to 2000 W/m2. The experimental results show that the Fuzzy Logic compensation scheme can reduce the sensor measurement error up to 17% and 20% for solar irradiance and PV temperature measurement.

Among other soft computing techniques, the Adaptive Neuro Fuzzy Inference System (Anfis) gives a significant and advantageous result in solar power generation, especially in tracking the maximum power point. Due to the dynamic nature of solar irradiance and temperature, efficient energy conversion is not possible. However, advancements in the areas of artificial intelligence have made it possible to overcome the hurdles. The Maximum Power Point Tracking (MPPT) technique adopting the advantages of Anfis has been proven to be more successful with a fast dynamic response and high accuracy. The complete system is modeled using Matlab/Simulink; the hardware results are validated with the benefits of Field Programmable Logic Array (FPGA) instead of ordinary micro-controllers.

Improvement of photovoltaic (PV) power plant performance under partial shading conditions aiming to increase electrical energy generation is in the focus of this research. This paper proposes the performance optimization of PV power plant under partial shading conditions by new PV string reconfiguration technique. The Matlab/Simulink model is used to simulate the operation of the PV string under partial shading conditions and with the proposed recombination technique. Simulated operational conditions have experimentally been verified by string characteristics measurement on the existing roof-top PV system at the Faculty of Technical Sciences in Novi Sad. Simulation and experimental results showed a high degree of matching, while the obtained values proved that proposed method leads to output power increase and higher PV system generation in PV string operation under partial shading.