Showing papers on "Grid-connected photovoltaic power system published in 2022"

Review and validation of photovoltaic solar simulation tools/software based on case study

Abstract: Abstract Photovoltaic (PV) systems are an excellent solution to meet energy demand and protect the global environment in many cases. With the increasing utilization of the PV system worldwide, there is an increasing need for simulation tools to predict the PV system’s performance and profitability. This research includes testing and comparison of PV tools: photovoltaic geographical information system (PVGIS), PVWatts, SolarGIS, RETScreen, BlueSol, PVsyst, HelioScope, PV*SOL, Solarius PV, Solar Pro, PV F-Chart, PolySun, solar advisor model (SAM), and hybrid optimization model for electric renewables (HOMER), based on experimental data obtained from fixed on-grid 2 kWp PV system in 2019. The PV system is part of a research project related to the examination of the PV system operation in real climatic conditions in Niš. This research investigates the most appropriate PV software for PV systems design by testing the most commonly used PV tools. It was accomplished by comparing experimental data obtained by a 2 kWp PV system in Niš and estimated data obtained from different PV tools. The study shows that annually, the experimentally measured average daily solar irradiation on the inclined plane was 5,270 Wh/m2/day, and the lowest deviation of the simulation results compared to experimental measurements was obtained by SolarPro. Total annual electricity production from the given system was 2455.621 kW h, and the lowest deviation of the simulation results compared to experimental measurements was obtained by PVGIS. By analyzing and publishing the actual solar irradiation and PV power output data, this study could help researchers to increase the PV systems modeling accuracy.

Fractional-Order Notch Filter for Grid-Connected Solar PV System With Power Quality Improvement

Abstract: In this article, we deal with the development of a fractional-order notch filter (FONF) for a grid-connected solar photovoltaic (PV) system. The developed FONF control approach is used to estimate fundamental active constituents from the distorted load currents, and hence, gating pulses for operating voltage source converter (VSC) are used in the PV system. This control approach for the grid-connected solar PV system is designed to achieve several purposes, such as feeding active power demand of the load/grid and countercurrent-related power quality issues at the common connecting point. The power quality issues taken into consideration are harmonics distortion, reactive power burden on the system, and unbalancing of connected loads. The FONF-based control proposes a modified structure of an integer-order notch filter. The integer-order filters have a limitation due to the fixed integrator and differentiator terms. In FONF, the power of integrator used in a notch filter can be modified according to the application required for obtaining the accurate response of the system. A prototype of the grid-connected solar PV system is developed in the laboratory using IGBTs based VSC and dSPACE MicroLabBox (DS-1202) to demonstrate the behavior of the FONF-based control. Simulation and experimental results are obtained for steady-state and unbalanced loads with variation in the solar irradiance. The harmonic distortions in the system are observed as per the IEEE-519 standard.

Grid connected photovoltaic system impression on power quality of low voltage distribution system

Abstract: Abstract To ensure the global energy demands and decarbonize the production of electricity, the expanded utilization of solar photovoltaics (PV) as a renewable energy resource has been increasing in recent decades, principally with the feasibility to be integrated with the conventional power grid. However, supplying clean power from PV grid-connected systems is often hampered by power quality (PQ) disturbances caused by the intermittent nature of solar radiation and other factors related to the grid, converters, and connected loads. To prevent deterioration of the power quality of the system, these disturbances must be mitigated. This paper technically studies some of these PQ issues, that is, the current total harmonic distortion (THD) which causes harmful effects on the whole connected power system and the linked loads. The case study works on a 5.5 kW grid-connected rooftop PV power system established at Benha Faculty of Engineering, Egypt, with the assistance of an installed weather station that boosts the validation of the research results. All aspects regarding the aforementioned small plant are presented including description and simulation of the whole system, review of current THD problems occurring at the point of common coupling (PCC), and a review of other disturbances observed by connected meters. A detailed examination of four techniques for harmonic mitigation, namely the on-off technique, LCL filter, active power filter, and hybrid active power filter is presented with a final comparison to assess the merits and demerits of each one. This research achieved a current harmonic limitation of 1.5%.

A PV-Battery System Resilient to Weak Grid Conditions With Regulated Power Injection and Grid Supportive Features

Abstract: This paper presents a weak grid coupled single stage photovoltaic (PV) system. The system incorporates a battery energy storage (BES) via a bi-directional DC-DC converter (BDDC). The system does not allow the grid power quality to be deteriorated at nonlinear loading conditions, as well as when the grid voltages are unbalanced or distorted. Moreover, the control scheme is resilient to DC offset in the acquired grid voltage signals due to sensor circuit anomalies. The flexibility afforded by the BES is utilized for several benefits. The intermittent power injection associated with the PV system, is resolved by sustaining the defined grid power at fluctuating PV generation or local loads. The developed control makes use of the BES to adjust the grid power with the feed-in tariffs, adding the capability to act as a power sink at low tariff periods, thus increasing the economic returns. The control avoids overcurrent tripping at large voltage dips and enables fault ride through, whereas the conventional single stage system frequently trips and ceases operation. The system helps the utility at large voltage rise by stopping power flow to the grid while allowing power import from the grid. The BES is prevented from being excessively charged or discharged by the monitored transfer to a recovery mode. Moreover, the dual mode control of the DC link voltage allows peak power extraction from the PV array, while conserving grid power quality. The claimed benefits are evaluated at different operating scenarios using simulated and test results.

Integrated design of solar photovoltaic power generation technology and building construction based on the Internet of Things

Abstract: At the same time of economic development, the increasing scarcity of energy has had a great impact on people's development. People's production and life demand for electricity is also increasing rapidly, and solar power technology has received more and more attention. As a new energy source, solar energy has the advantages of environmental protection and sustainability, and it has no regional restrictions, can be used on-site, and designed to scale. Solar power generation is an important way to use solar energy. As the main component of the grid-connected power generation system, solar grid-connected inverters complete the tracking problem of the maximum power point in the photovoltaic array and transmit electrical energy to the grid through a set of control algorithms. The electrical energy is transmitted to the grid through the inverter, consistent with solar energy. In order to solve the problems of low integration, low energy efficiency, low reliability, high power consumption and lack of effective monitoring measures for solar energy devices. This article starts with the design of the solar cell integrated system, and through detailed analysis of the solar production system and building integrated planning, establishes the shadow radiant energy model of the solar cell system building electrical and solar cell system based on the Internet of Things, and designs an object-based Networked comprehensive auxiliary platform. The use of the Internet of Things and ZigBee wireless sensor network to study distributed solar energy devices and realize the joint design of solar energy devices and buildings is of great significance to the development of photovoltaic construction industry.

Solar PV-Fed Multilevel Inverter With Series Compensator for Power Quality Improvement in Grid-Connected Systems

Abstract: Power quality difficulties arise as a result of Renewable Energy Sources (RES) integrating with the grid. Voltage swell, sag, and harmonic distortion occur on the grid due to power quality issues, which have an impact on customers. An inexpensive series compensator, like the Dynamic Voltage Restorer (DVR), is the best solution for overcoming the aforementioned problems. In this article, a solar PV integrated DVR with a novel multilevel inverter is introduced to address the power quality issues in the grid. The main objective of the proposed work is to develop a DVR integrated with a 23-level multilevel inverter to enhance the power quality. In addition, an improved INC-MPPT technique is designed for the boost converter for maximum energy extraction from the solar PV modules. Despite numerous benefits of multilevel inverters, there exist several reliability challenges such as fewer component counts and reduced THD. The suggested topology can able to generate 23 levels of output voltage with asymmetrical DC sources. The MLI has several advantages such as a reduction in the overall component count, cost and size of the inverter. Additionally, a detailed mathematical analysis is presented for the rotating dq reference frame control. The dynamic performance of the DVR is evaluated with a balanced load and implemented experimentally. Simulation results of the proposed system are carried out using MATLAB/Simulink. The proposed system is implemented using a dSPACE controller with a laboratory hardware prototype and OPAL-RT real-time simulator setup as well. The results show that the design of the proposed system is more effective at compensating for voltage sag and improves the power quality significantly. The THD obtained at the grid side is lower, which is under IEEE standards.

Current Reference Control Based MPPT and Investigation of Power Management Algorithm for Grid-Tied Solar PV-Battery System

Abstract: To achieve unity power factor operation, harmonic mitigation, faster dc-link voltage regulation, and smooth transfer of modes of operation, this work aims to propose an adaptive control scheme for a photovoltaic (PV) grid-tied power conversion system. The grid-tied PV system consists of a battery storage unit interfaced with the dc link using a bidirectional converter and dc link is connected to the ac bus using a voltage source converter. Apart from the mentioned control objectives, maximum power extraction from the PV systems and effective power management for seamless operation are also challenging. The shortcoming of the conventional maximum power point tracking technique to track global power under varying environmental conditions is addressed by developing a simple and efficient current reference control technique, which enables faster tracking of the global maximum power. Furthermore, a suitable power management algorithm is formulated to generate reference currents for all the power converters in the proposed system, considering various system dynamics. The viability of the control scheme for the PV-battery-based grid-tied system is validated through extensive real-time investigation under dynamic test conditions.

An Uninterruptable PV Array-Battery Based System Operating in Different Power Modes With Enhanced Power Quality

Abstract: This article aims to develop a solar- battery energy storage (BES) based system, which ensures an uninterruptable supply to loads irrespective of availability of the grid. This system comprises of a solar photovoltaic (PV) array, a BES, the grid and local residential loads. A new control is implemented such that the active power demand of residential loads, is fed from the PV array, a BES unit and the utility grid. In this system, the power control operates in different power modes, which delivers the benefits to the end users with an integration of BES and an excess of PV array power, which is sold back to the grid. For this, an effective control logic is developed for the grid tied voltage source converter. Moreover, this system deals with the issue of an integrating power quality enhancement along with the power generation from the solar PV source. The cascaded delayed signal cancellation based phase locked loop is implemented for grid synchronization during the grid voltage distortion. The developed control is easily implemented in a real time controller (dSPACE-1202). Test results validate the performance of the implemented control in different operating conditions such as varying solar power generation, load variations and unavailability of the grid.

Grid-Forming and Grid-Following Based Microgrid Inverters Control

Abstract: Microgrids (ℳ-grids) can be thought of as a small-scale electrical network comprised of a mix of Distributed Generation (DG) resources, storage devices, and a variety of load species. It provides communities with a stable, secure, and renewable energy supply in either off-grid (grid-forming) or on-grid (grid-following) mode. In this work, a control strategy of coordinated power management for a Low Voltage (LV) ℳ-grid with integration of solar Photovoltaic (PV), Battery Energy Storage System (BESS) and three phase loads operated autonomously or connected to the utility grid has been created and analyzed in the Matlab Simulink environment. The main goal expressed here is to achieve the following points: (i) grid following, grid forming modes, and resynchronization mode between them, (ii) Maximum Power Point Tracking (MPPT) from solar PV using fuzzy logic technique, and active power regulator based boost converter using a Proportional Integral (PI) controller is activated when a curtailment operation is required, (iii) ℳ-grid imbalance compensation (negative sequence) due to large single-phase load is activated, and (iv) detection and diagnosis the fault types using Discrete Wavelet Transform (DWT). Under the influence of irradiance fluctuation on solar plant, the proposed control technique demonstrates how the adopted system works in grid-following mode (PQ control), grid- formation, and grid resynchronization to seamlessly connect the ℳ-grid with the main distribution system. In this system, a power curtailment management system is introduced in the event of a significant reduction in load, allowing the control strategy to be switched from MPPT to PQ control, permitting the BESS to absorb excess power. Also, in grid-following mode, the BESS’s imbalance compensation mechanism helps to reduce the negative sequence voltage that occurs at the Point of Common Coupling (PCC) bus as a result of an imbalance in the grid’s power supply. In addition to the features described above, this system made use of DWT to detect and diagnose various fault conditions.

Improved Gaussian Filter Based Solar PV-BES Microgrid With PLL Based Islanding Detection and Seamless Transfer Control

Abstract: This article presents an improved Gaussian filter with phase-locked loop based grid monitoring and seamless transfer control for solar photovoltaic-battery energy storage (PV-BES) based microgrid with improved power quality. The PV-BES microgrid comprises of a PV array and a battery, interfaced to the utility through a voltage source converter, and performs multiple tasks. In grid-connected mode, the improved Gaussian filter with quadrature signal generator-based second-order generalized integrator based prefiltering provides solar PV power to the nonlinear loads and the utility grid, along with providing reactive power compensation and power quality improvement at the point of common coupling. To regulate the power absorbed or discharged by the BES, a bidirectional converter is used. The PV feed-forward term enables PV power injection and also improves the dynamic performance of the system. On grid outage, the controller transits the PV-BES microgrid to standalone mode of operation ensuring uninterrupted supply to the load. The effectiveness of the controller is tested in various scenarios and is verified through experimentation. The controller has satisfied the specifications set by the IEEE 519-2014 power quality standard and IEEE 1547-2018 (revised) standard for interconnection and interoperability of distributed energy resources.

Fractional-Order Notch Filter for Grid-Connected Solar PV System With Power Quality Improvement

Abstract: In this article, we deal with the development of a fractional-order notch filter (FONF) for a grid-connected solar photovoltaic (PV) system. The developed FONF control approach is used to estimate fundamental active constituents from the distorted load currents, and hence, gating pulses for operating voltage source converter (VSC) are used in the PV system. This control approach for the grid-connected solar PV system is designed to achieve several purposes, such as feeding active power demand of the load/grid and countercurrent-related power quality issues at the common connecting point. The power quality issues taken into consideration are harmonics distortion, reactive power burden on the system, and unbalancing of connected loads. The FONF-based control proposes a modified structure of an integer-order notch filter. The integer-order filters have a limitation due to the fixed integrator and differentiator terms. In FONF, the power of integrator used in a notch filter can be modified according to the application required for obtaining the accurate response of the system. A prototype of the grid-connected solar PV system is developed in the laboratory using IGBTs based VSC and dSPACE MicroLabBox (DS-1202) to demonstrate the behavior of the FONF-based control. Simulation and experimental results are obtained for steady-state and unbalanced loads with variation in the solar irradiance. The harmonic distortions in the system are observed as per the IEEE-519 standard.

A systematic review of grid-connected photovoltaic and photovoltaic/thermal systems: Benefits, challenges and mitigation

Abstract: Solar energy is the powerhouse where all potential and classified renewable energies lug their sources. The energy transformation from the Sun to electricity requires an adequate control scheme to maximise the generated power and enhance the system efficiency. Besides, more than half of solar irradiation on conventional PV panels is lost. The PV/T modules have been introduced to convert the lost irradiation to heat. Thus, a systematic review of system components, development, and strategies for grid-connected solar Photovoltaics (PVs) plants is presented. Two solar PVs, traditional PV and thermal (PV/T), are evaluated. Each grid-tied PV component is considered a subsystem to analyse the potential improvement of grid-connected PVs. This is from solar resources to grid-tied PV inverter techniques. An intensive assessment of the system improvements is presented to evaluate PV plants’ benefits, challenges, and potential solutions. The improvement trends for the novel generation of grid-connected PV systems consist of applying innovative approaches. It is also found that intelligent strategies optimally ensure the overall efficiency of grid-tied PVs using real-time control and measurement under innovative applications and technologies. These methods effectively assist in enhancing grid-tied diverse solar power approaches. Therefore, this paper would offer a significant foundation for advanced research into the subject of grid-tied PV and PV/T and their innovation and/or technology development.

Grid-Forming Inverters for Grid-Connected Microgrids: Developing “good citizens” to ensure the continued flow of stable, reliable power

Abstract: The electric power grid is in transition. For nearly 150 years it has supplied power to homes and industrial loads from synchronous generators (SGs) situated in large, centrally located stations. Today, we have more and more renewable energy sources—photovoltaic (PV) solar and wind—connected to the grid by power electronic inverters. These inverter-based resources (IBRs) do not have the same characteristics as SGs, such as inertia and high fault current. This mismatch has not been a problem until now. Inverters have assumed that the grid is strong and will provide a stable and clean voltage and that they are able to inject real power into the grid without undue impact on its operation.

A New Six-Level Transformer-Less Grid-Connected Solar Photovoltaic Inverter With Less Leakage Current

Abstract: This paper presents a novel structure of the transformer-less grid-connected inverters. The proposed inverter is combined with six power switches and two power diodes which can generate six voltage levels at the output. Furthermore, the proposed inverter can overcome the leakage current issue in the photovoltaic (PV) system, which is the major problem in grid-tied PV applications. Additional significant features include-reduced filter size, lower total harmonic distortion (THD) of the injected current to the grid, and voltage boosting ability. Moreover, the proposed topology provides full reactive power support to the grid. A control strategy is designed and implemented to provide a voltage boost ability without using any additional dc-dc boost converter. Finally, the performance of the proposed inverter is validated by the 770 W laboratory prototype.

Modelling of Solar PV under Varying Condition with an Improved Incremental Conductance and Integral Regulator

Abstract: The introduction of solar photovoltaic (PV) systems would provide electricity accessibility to rural areas that are far from or have no access to the grid system. Various countries are planning to reduce their emissions from fossil fuel, due to its negative effects, by substituting with renewable energy resources. The use of solar PV systems is expanding globally because of growing energy demands and depleting fossil fuel reserves. Grid integration of the solar system is expected to increase further in the near future. However, the power output of solar PV systems is inherently intermittent, and depends on the irradiance and the temperature operation of the solar cell, resulting in a wide range of defects. Hence, it is vital to extract peak power from the solar panel in all conditions to provide constant power to the load. This paper presents a tracking control method of the peak output power of a solar PV system connected to a DC-DC boost converter using an improved incremental conductance and integral regulator (IC + IR). The research was carried out because the solar PV output is dependent on environmental parameters, such as solar insolation and temperature. Therefore, it is pertinent to forecast the peak power point in outdoor conditions and to operate at that point, so that solar PV can produce the highest output each time it is used. A peak power point strategy that maximizes the output of a solar PV array is proposed. This method establishes the maximum output operation point under the effects of the solar insolation and the module temperature. An automatic converter restoration scheme with block/de-block signal control is proposed to protect the converters from the higher phase current, total capacitor voltage deviation, grid disturbance, and fault current. The proposed scheme also tracks the peak power point (PPP) of the solar array with stable output voltage under varying operating conditions. It reduces the error signal and ripples at the PPP during instantaneous and incremental conductance to zero. In addition, it controls the solar PV system under constantly changing climatic conditions, and thus improves the system efficiency.

Enhanced Power Quality PV Inverter With Leakage Current Suppression for Three-Phase SECS

Abstract: This article presents an enhanced power quality solar photovoltaic (PV) inverter enabling common-mode leakage current elimination. A three-phase transformerless solar energy conversion system is considered here, which, along with peak active-power production from PV array, ensures different power quality improvement capabilities such as grid current harmonics mitigation, grid currents balancing while also offering the grid reactive power support. Unlike conventional power quality inverters, this strategy is robust with respect to abnormalities in grid voltages at far radial ends, and does not compromise with the leakage currents caused by parasitic capacitance of PV array with ground. Common practice in the PV inverter power quality control is to neglect the PV leakage currents; however, they considerably affect the system performance by deteriorating the power quality and causing the safety issues of operating personnel. The standards VDE-00126 and NB/T-32004, therefore, compel the transformerless PV systems to operate with leakage current under 300 mA range. Various simulation and test results show the satisfactory performance of the presented strategy, even under various grid-side abnormalities. The comparative analysis with the state-of-the-art techniques shows the effectiveness of the strategy. Under all test conditions, the harmonics in grid currents are observed within limits as per the IEEE-519 and IEC-61727 standards, whereas the PV leakage currents are maintained well within the range recommended by VDE-00126 standard.

Multilevel Converter With Nearest Level Control for Integrating Solar Photovoltaic System

Abstract: This article presents a new Scott-ternary solar multilevel converter (ST-MLC)-based solar photovoltaic (PV) system for medium voltage applications. This system employs a single solar PV array as an input source and two voltage source converters (VSCs) to feed a three-phase grid. Solar power is fed from a two-phase to a three-phase medium voltage grid with balanced grid currents. The legs of VSCs are cascaded to form a two-phase system. The multiwinding transformers are connected in a Scott manner to develop a nine-level three-phase power conditioning system. The turn ratios of the transformers have ternary progression for the generation of higher levels. The modeling of the system is presented, and a closed-loop nearest level control strategy is incorporated to have minimum losses. Simulation results show the performance of the solar PV system under steady-state and dynamic irradiance. Varying solar profile is considered on basis of the daily average global solar irradiance from the geographical information system for New Delhi, India. The harmonic performance is analyzed for the converter voltage and grid current. Moreover, a detailed comparative analysis is covered for the ST-MLC to evaluate its superiority over its existing counterparts. Performance validation is done in a real-time test bench to validate the control and operation of the large-scale solar PV system.

Multi-Functional PV Inverter With Low Voltage Ride-Through and Constant Power Output

Abstract: Renewable photovoltaic (PV) energy is a primary contributor to sustainable power generation in microgrids. However, PV grid-tied generators remain functional as long as the grid voltage and the input PV source remain normal. Abnormal conditions like transient grid sags or solar irradiation flickering can make the grid-tied inverter go offline. Simultaneous shut down of PV generators residing in the distribution grid may lead to an overall grid instability or outage. Therefore, PV generators must be equipped with fault-ride-through mechanisms in order to remain connected and operational during faults. This paper presents a PV-inverter with low-voltage-ride-through (LVRT) and low-irradiation (LR) compensation to avoid grid flickers. The single-phase inverter rides through the voltage sags while injecting reactive power into the grid. The proposed control strategy ensures a steady DC-link voltage and remains connected to the grid during AC-side low voltage and DC-side low-irradiation faults. Unlike other PV inverters, the controller maintains the maximum-power-point-tracking (MPPT) in all conditions. LVRT, constant power output, and robust MPPT are the noticeable features of the proposed system. Frequency analysis, simulations, and a laboratory prototype validate the proposed control strategy.

A grid-connected single-stage closed-loop controlled five-level boosting inverter for solar PV systems

Abstract: Multilevel inverters (MLIs) have gotten a lot of attention recently in the power industry because of their efficiency. The application of MLI in photovoltaic (PV) systems to improve power quality and performance has grown dramatically. An innovative, low-component-count 5-L boosting inverter interfaces a single-stage grid-tied PV system with a closed-loop control method in this research. The proposed MLI is put to the test using a 2.1 kW PV system. This technique guarantees optimum power monitoring, DC link voltage balancing, appropriate MLI operation and injection of clean sinusoidal grid current. The suggested system’s outcome is tested by Matlab/Simulink.

Performance Analysis of an Optimized Asymmetric Multilevel Inverter on Grid Connected SPV System

Abstract: The purpose of this research is to develop an efficient single-phase grid-connected PV system using a better performing asymmetrical multilevel inverter (AMI). Circuit component reduction, harmonic reduction, and grid integration are critical criteria for better inverter efficiency. The proposed inverter’s optimized topology requires seven unidirectional switches, three symmetric dc sources, and three diodes to produce an asymmetric fifteen level output; whereas, the same configuration will generate 7, 11, and 15-level output with an appropriate choice of dc source magnitudes. It is possible to reduce inverter losses and boost efficiency by decreasing the number of switches used. The integration of an asymmetric 15-level inverter with a grid-connected solar photovoltaic system is discussed in this article. A grid-connected solar photovoltaic (GCSPV) system is modelled and simulated using an asymmetric 15-level inverter. The dc sources of the 15-level inverter are replaced with PV sources. The results were analyzed with different operating temperatures and solar irradiance conditions. The GCSPV system is controlled by a closed-loop control system using Particle Swarm Optimization (PSO), Harris Hawk Optimization (HHO), and Hybrid Particle Swarm Optimization-Genetic Algorithm (PSOGA) based Proportional plus Integral (PI) controllers. Grid voltage, grid current, grid power, and total harmonic distortion (THD) of grid currents were analyzed. The performance of the 15-level asymmetric inverter was evaluated by comparing the THD of the grid current and the efficiency of the grid-connected photovoltaic system.

Intelligent Transition Control Approach for Different Operating Modes of Photovoltaic Inverter

Abstract: The increasing photovoltaic (PV) installations and their integration with the utilities have complexed the operation of the power system network making them vulnerable to various faults and abnormalities. The traditional methods developed to handle this problem are aimed to explore the ability of PV inverter to operate in standalone (SA) mode when there are predictable grid side abnormalities or scheduled maintenances. In this article, a grid condition monitoring based transition control approach is developed using machine learning algorithm and a hybrid control strategy. This article is motivated at handling the intentional and unintentional islanding conditions by operating the PV system in both grid-connected (GC) and SA modes. The switching between the controllers is performed by the central controller ensuring a smooth transition and continuous power delivery to the load. For validating the claims, numerical simulations and experimental analysis are carried out with a 4 kWp GC PV system. The results depicted fast grid condition monitoring under 20 ms and smooth transition without any transients or harmonics.

Hierarchical Control of Utility-Scale Solar PV Plants for Mitigation of Generation Variability and Ancillary Service Provision

Abstract: This paper presents a hierarchical control system to mitigate the variability of solar photovoltaic (PV) power plant and provide ancillary services to the electric grid without the need for additional non-solar resources. With coordinated management of each inverter in the system, the control system commands the power plant to proactively curtail a small fraction of its instantaneous maximum power potential, which gives the plant enough headroom to ramp up production from the overall power plant, for a service such as regulation reserve. This control system is practical for continuously changing cloud cover conditions in partially cloudy days. A case study from a site in Hawaii with one-second resolution solar irradiance data is used to verify the efficacy of the proposed control system. The proposed control algorithm is subsequently compared with the alternative control technology from the literature, the grouping control algorithm; the results show that the proposed hierarchical control system is over 10 times more effective in reducing generator mileage to support power fluctuations from solar PV power plants.

Efficient Smart Micro Scale Solar Power Management System for Rechargeable Nodes

Abstract: Solar energy has been the most used form of renewable source of energy because of its nature of being abundant and eco-friendly to the environment. Solar systems are generally two types, on-Grid, and off-Grid. In Off-Grid solar systems power is stored in the battery regardless of the amount of energy produced, whereas, in On-Grid type solar systems, the user can draw electricity from the grid when the solar battery is low and can also send electricity back to the grid when there is excess solar power produced and will get paid by the government accordingly. In the On-Grid type systems when power is sent back to the grid there exist some phases and the voltage difference between the grid power and solar power. This solar power needs to be fed to the transformer to step up the voltage and sent to the grid. The amount of current sent to the grid decreases to increase the voltage of the power. The best way to avoid this step-up process is to smartly divert this solar power using IOT signals to the nearby households. The Wi-Fi module calculates and displays the amount of electricity produced and shared with a neighbour in the cloud.

Experimental Evaluation of Distortion Effect for Grid-Connected PV Systems with Reference to Different Types of Electric Power Quantities

Abstract: Aware of the fact that the installed PV capacity and its power production rapidly increased in the last decade, with the huge impact that has been done to the power system, the distortion effects for grid-connected PV systems with reference to different types of electric power quantities will be presented in this article. The impact of the frequent fluctuation of solar irradiance on the behavior of the grid-connected PV system, due to cloud movements and resulting shadows and in terms of power quality and the evaluation of power components, is the topic of analysis in this research. Besides the simulation results of certain study cases, an experimental evaluation of electric power quantities on an actual PV system in real weather conditions was also performed. The experimental setup, formed through the combination of a PC and multifunctional I/O board with an appropriate software solution, was established and used for obtaining the target results. The methodology used for the evaluation of electric power quantities relied on the current physical components (CPC) theory for power definition. The experimental results were obtained for three different cases, namely, the low, medium, and high solar irradiance cases. On the basis of these results, the conclusions about distortion effects are given.

A Harmonic Mitigation Technique for Multi-Parallel Grid-Connected Inverters in Distribution Networks

Abstract: Different harmonic mitigation techniques have been utilized in grid-connected inverters to suppress the effect of grid voltage distortion on the output current of these inverters. In practice, to scale up the injected current into the grid, a set of parallel grid-connected inverters are often utilized rather than a single high-power inverter in solar Photovoltaic or motor drive systems. Conventional Point of Common Coupling (PCC) feedforward approaches have been used for harmonic rejection of multi-parallel grid-connected inverters. However, these methods need to implement a separate feedforward scheme for each individual inverter. In this paper, a novel full PCC voltage feedforward strategy is proposed to reduce the cost investment, which is implemented only in one of the grid-connected inverters. The proposed strategy is based on cancelling the total parallel admittance of the system by adding a virtual negative admittance to the target inverter. It is shown that the proposed scheme causes no instability issue on the system since it does not affect the system phase margin. To verify the efficiency of the proposed strategy against emitted harmonics from the grid, simulations and experiments on a system with two parallel single-phase grid-tied inverters are performed.