Showing papers on "Grid-connected photovoltaic power system published in 2013"

A Comparative Study on Maximum Power Point Tracking Techniques for Photovoltaic Power Systems

Abstract: This paper provides a comprehensive review of the maximum power point tracking (MPPT) techniques applied to photovoltaic (PV) power system available until January, 2012. A good number of publications report on different MPPT techniques for a PV system together with implementation. But, confusion lies while selecting a MPPT as every technique has its own merits and demerits. Hence, a proper review of these techniques is essential. Unfortunately, very few attempts have been made in this regard, excepting two latest reviews on MPPT [Salas, 2006], [Esram and Chapman, 2007]. Since, MPPT is an essential part of a PV system, extensive research has been revealed in recent years in this field and many new techniques have been reported to the list since then. In this paper, a detailed description and then classification of the MPPT techniques have made based on features, such as number of control variables involved, types of control strategies employed, types of circuitry used suitably for PV system and practical/commercial applications. This paper is intended to serve as a convenient reference for future MPPT users in PV systems.

Impact of increased penetration of photovoltaic generation on power systems

Abstract: Present renewable portfolio standards are changing power systems by replacing conventional generation with alternate energy resources such as photovoltaic (PV) systems. With the increase in penetration of PV resources, power systems are expected to experience a change in dynamic and operational characteristics. This paper studies the impact of increased penetration of PV systems on static performance as well as transient stability of a large power system, in particular the transmission system. Utility scale and residential rooftop PVs are added to the aforementioned system to replace a portion of conventional generation resources. While steady state voltages are observed under various PV penetration levels, the impact of reduced inertia on transient stability performance is also examined. The studied system is a large test system representing a portion of the Western U.S. interconnection. The simulation results obtained effectively identify both detrimental and beneficial impacts of increased PV penetration both for steady state stability and transient stability performance.

Classification and comparison of maximum power point tracking techniques for photovoltaic system: A review

Abstract: In recent years there has been a growing attention towards use of solar energy. The main advantages of photovoltaic (PV) systems employed for harnessing solar energy are lack of greenhouse gas emission, low maintenance costs, fewer limitations with regard to site of installation and absence of mechanical noise arising from moving parts. However, PV systems suffer from relatively low conversion efficiency. Therefore, maximum power point tracking (MPPT) for the solar array is essential in a PV system. The nonlinear behavior of PV systems as well as variations of the maximum power point with solar irradiance level and temperature complicates the tracking of the maximum power point. A variety of MPPT methods have been proposed and implemented. This review paper introduces a classification scheme for MPPT methods based on three categories: offline, online and hybrid methods. This classification, which can provide a convenient reference for future work in PV power generation, is based on the manner in which the control signal is generated and the PV power system behavior as it approaches steady state conditions. Some of the methods from each class are simulated in Matlab/Simulink environment in order to compare their performance. Furthermore, different MPPT methods are discussed in terms of the dynamic response of the PV system to variations in temperature and irradiance, attainable efficiency, and implementation considerations.

Distributed Volt/VAr Control by PV Inverters

Abstract: A major technical obstacle for rooftop photovoltaics (PV) integration into existing distribution systems is the voltage rise due to the reverse power flow from the distributed PV sources. This paper describes the implementation of a voltage control loop within PV inverters that maintains the voltage within acceptable bounds by absorbing or supplying reactive power. In principle, this can be considered to be a form of distributed Volt/VAr control, which is conventionally performed by coordinated control of capacitor banks and transformer tap changers. Comprehensive simulation studies on detailed feeder models are used to demonstrate that the proposed control scheme will mitigate voltage rises.

Grid-Connected Photovoltaic Generation Plants: Components and Operation

Abstract: The main design objective of photovoltaic (PV) systems has been, for a long time, to extract the maximum power from the PV array and inject it into the ac grid. Therefore, the maximum power point tracking (MPPT) of a uniformly irradiated PV array and the maximization of the conversion efficiency have been the main design issues. However, when the PV plant is connected to the grid, special attention has to be paid to the reliability of the system, the power quality, and the implementation of protection and grid synchronization functions. Modern power plants are required to maximize their energy production, requiring suitable control strategies to solve the problems related to the partial shading phenomena and different orientation of the PV modules toward the sun. Moreover, the new policy concerning the injection of reactive power into the grid makes the development of suitable topologies and control algorithms mandatory. A general view of actual solutions for applications of the PV energy systems is presented. This article covers several important issues, including the most reliable models used for simulation, which are useful in the design of control systems, and the MPPT function, particularly in distributed applications. The main topologies used in the PV power processing system and, finally, grid connection aspects are discussed, with emphasis on synchronization, protections, and integration.

MPPT techniques for photovoltaic applications

Abstract: The photovoltaic (PV) system is one of the renewable energies that attract the attention of researchers in the recent decades. The PV generators exhibit nonlinear I–V and P–V characteristics. The maximum power produced varies with both irradiance and temperature. Since the conversion efficiency of PV arrays is very low, it requires maximum power point tracking (MPPT) control techniques. The maximum power point tracking (MPPT) is the automatic control algorithm to adjust the power interfaces and achieve the greatest possible power harvest, during moment to moment variations of light level, shading, temperature, and photovoltaic module characteristics. The purpose of the MPPT is to adjust the solar operating voltage close to the MPP under changing atmospheric conditions. It has become an essential component to evaluate the design performance of PV power systems. This investigation aims to assess different MPPT techniques, provide background knowledge, implementation topology, grid interconnection of PV and solar microinverter requirements presented in the literature, doing depth comparisons between them with a brief discussion. The MPPT merits, demerits and classification, which can be used as a reference for future research related to optimizing the solar power generation, are also discussed. Conventional methods are easy to implement but they suffer from oscillations at MPP and tracking speed is less due to fixed perturb step. Intelligent methods are efficient; oscillations are lesser at MPP in steady state and tracked quickly in comparison to conventional methods.

Improved Low Voltage Grid-Integration of Photovoltaic Systems in Germany

Abstract: This work discusses the technical and economical benefits of different active and reactive power control strategies for grid-connected photovoltaic systems in Germany. The aim of these control strategies is to limit the voltage rise, caused by a high local photovoltaic power feed-in and hence allow additional photovoltaic capacity to be connected to the mains. Autonomous inverter control strategies, which do not require any kind of data communication between the inverter and its environment, as well as an on-load tap changer for distribution transformers, is investigated. The technical and economical assessment of these strategies is derived from 12-month root mean square (rms) simulations, which are based on a real low voltage grid and measured dc power generation values. The results show that the provision of reactive power is an especially effective way to increase the hosting capacity of a low voltage grid for photovoltaic systems.

Analytical model for solar PV and CSP electricity costs: Present LCOE values and their future evolution

Abstract: In this paper we first make a review of the past annual production of electricity and the cumulative installed capacity for photovoltaic (PV) and concentrating solar power (CSP) technologies. This together with the annual costs of PV modules and CSP systems allows us the determination of the experience curves and the corresponding learning rates. Then, we go over a rigorous exposition of the methodology employed for the calculation of the value of the levelized cost of electricity (LCOE) for PV and CSP. Based on this knowledge, we proceed to establish a mathematical model which yields closed-form analytical expressions for the present value of the LCOE, as well as its future evolution (2010–2050) based on the International Energy Agency roadmaps for the cumulative installed capacity. Next, we explain in detail how specific values are assigned to the twelve independent variables which enter the LCOE formula: solar resource, discount and learning rates, initial cost and lifetime of the system, operational and maintenance costs, etc. With all this background, and making use of a simple computer simulation program, we can generate the following: sensitivity analysis curves, graphs on the evolution of the LCOE in the period 2010–2050, and calculations of the years at which grid parities will be reached. These representations prove to be very useful in energy planning policies, like tariff-in schemes, tax exemptions, etc., and in making investment decisions, since they allow, for a given location, to directly compare the costs of PV vs CSP power generation technologies for the period 2010–2050. Among solar technologies, PV seems always more appropriate for areas located in middle to high latitudes of the Earth, while CSP systems, preferably with thermal storage incorporated, yield their best performance in arid areas located at relatively low latitudes.

An Improved Optimal Sizing Method for Wind-Solar-Battery Hybrid Power System

Abstract: This paper proposes an improved optimal sizing method for wind-solar-battery hybrid power system (WSB-HPS), considering the system working in stand-alone and grid-connected modes. The proposed method is based on the following principles: a) high power supply reliability; b) full utilization of the complementary characteristics of wind and solar; c) small fluctuation of power injected into the grid; d) optimization of the battery's charge and discharge state; e) minimization of the total cost of system. Compared with the traditional methods, the proposed method can achieve a higher power supply reliability while require less battery capacity in stand-alone mode. And in grid-connected mode, the optimization strategy based on energy filter is further utilized to achieve the optimal battery capacity. Thus, the proposed method can achieve a much smaller fluctuation of power injected into the grid. In addition, the battery's charge and discharge state can be optimized thanks to the consideration of the battery's depth of discharge (DOD), the charge/discharge current, rate and cycles, which will prolong the battery's lifetime. A case study of WSB-HPS located in Hohhot, China is presented to verify the advantages of the proposed optimal sizing method.

Land-Use Requirements for Solar Power Plants in the United States

Abstract: This report provides data and analysis of the land use associated with utility-scale ground-mounted solar facilities, defined as installations greater than 1 MW. We begin by discussing standard land-use metrics as established in the life-cycle assessment literature and then discuss their applicability to solar power plants. We present total and direct land-use results for various solar technologies and system configurations, on both a capacity and an electricity-generation basis. The total area corresponds to all land enclosed by the site boundary. The direct area comprises land directly occupied by solar arrays, access roads, substations, service buildings, and other infrastructure. As of the third quarter of 2012, the solar projects we analyze represent 72% of installed and under-construction utility-scale PV and CSP capacity in the United States.

Storage Size Determination for Grid-Connected Photovoltaic Systems

Abstract: In this paper, we study the problem of determining the size of battery storage used in grid-connected photovoltaic (PV) systems In our setting, electricity is generated from PV and is used to supply the demand from loads Excess electricity generated from the PV can be either sold back to the grid or stored in a battery, and electricity must be purchased from the electric grid if the PV generation and battery discharging cannot meet the demand Due to the time-of-use electricity pricing and net metered PV systems, electricity can also be purchased from the grid when the price is low, and be sold back to the grid when the price is high The objective is to minimize the cost associated with net power purchase from the electric grid and the battery capacity loss while at the same time satisfying the load and reducing the peak electricity purchase from the grid Essentially, the objective function depends on the chosen battery size We want to find a unique critical value (denoted as Crefc ) of the battery size such that the total cost remains the same if the battery size is larger than or equal to Crefc, and the cost is strictly larger if the battery size is smaller than Crefc We obtain a criterion for evaluating the economic value of batteries compared to purchasing electricity from the grid, propose lower and upper bounds on Crefc, and introduce an efficient algorithm for calculating its value; these results are validated via simulations

Maximum power point tracking control techniques: State-of-the-art in photovoltaic applications

Abstract: A photovoltaic (PV) array has non-linear I–V (current–voltage) characteristics and its output power varies with solar insolation level and ambient temperature. There exists only one point, called maximum power point (MPP), on the P–V (power–voltage) curve, where power is maximum and this point varies with the changing atmospheric conditions. Moreover, energy conversion efficiency of PV module is very low and mismatch between source and load characteristics causes significant power losses. Consequently, maximization of power output with greater efficiency is extremely important. Maximum power point tracking (MPPT) is a technique employed to extract maximum power available from the PV module. It traces the PV operating voltage corresponding to the MPP and locks the operating point at MPP and extract maximum power from the array. Till date, many algorithms for MPPT have been reported, each with its own features. In this paper, a comprehensive presentation of working principle of these techniques is made and they are compared against each other in terms of some critical parameters like: number of variables used, complexity, accuracy, speed, hardware implementation, cost, tracking efficiency and so on. This study is aimed at providing a compendium on MPPT techniques for an appropriate selection, based on application requirements and system constraints.

Mitigation of Rooftop Solar PV Impacts and Evening Peak Support by Managing Available Capacity of Distributed Energy Storage Systems

Abstract: A high penetration of rooftop solar photovoltaic (PV) resources into low-voltage (LV) distribution networks creates reverse power-flow and voltage-rise problems This generally occurs when the generation from PV resources substantially exceeds the load demand during high insolation period This paper has investigated the solar PV impacts and developed a mitigation strategy by an effective use of distributed energy storage systems integrated with solar PV units in LV networks The storage is used to consume surplus solar PV power locally during PV peak, and the stored energy is utilized in the evening for the peak-load support A charging/discharging control strategy is developed taking into account the current state of charge (SoC) of the storage and the intended length of charging/discharging period to effectively utilize the available capacity of the storage The proposed strategy can also mitigate the impact of sudden changes in PV output, due to unstable weather conditions, by putting the storage into a short-term discharge mode The charging rate is adjusted dynamically to recover the charge drained during the short-term discharge to ensure that the level of SoC is as close to the desired SoC as possible A comprehensive battery model is used to capture the realistic behavior of the distributed energy storage units in a distribution feeder The proposed PV impact mitigation strategy is tested on a practical distribution network in Australia and validated through simulations

Building Integrated Photovoltaic System With Energy Storage and Smart Grid Communication

Abstract: The utility grid challenge is to meet the current growing energy demand. One solution to this problem is to expand the role of microgrids that interact with the utility grid and operate independently in case of a limited availability during peak time or outage. This paper proposes, for urban areas, a building integrated photovoltaic (BIPV) primarily for self-feeding of buildings equipped with PV array and storage. With an aim of elimination of multiple energy conversions, a DC network distribution is considered. The BIPV can supply a tertiary building at the same time as PV array may produce power through a hierarchical supervision able to exchange messages with the smart grid and metadata. The hierarchical control is designed as an interface to expand the system ability for advanced energy management control having regard to the grid availability and user's commands. It consists of four layers: human-machine interface, prediction, cost management, and operation. The operation layer, implemented in an experimental platform, takes into account the grid supply power limits and constrains the DC load. The experimental results validate the approach that may be a solution for the future smart grid communication between BIPV and utility grid.

Time in the Sun: The Challenge of High PV Penetration in the German Electric Grid

Abstract: Energy supply systems are facing significant changes in many countries around the globe. A good example of such a transformation is the German power system, where renewable energy sources (RESs) are now contributing 25% of the power needed to meet electricity demand, compared with 5% only 20 years ago. In particular, photovoltaic (PV) systems have been skyrocketing over the last couple of years. As of September 2012, about 1.2 million PV systems were installed, with a total installed peak capacity of more than 31 GWp. During some hours of 2012, PV already contributed about 40% of the peak power demand. It seems that Germany is well on the way to sourcing a major portion of its energy needs from solar installations. PV must therefore provide a full range of services to system operators so as to replace services provided by conventional bulk power plants.

An Energy-Stored Quasi-Z-Source Inverter for Application to Photovoltaic Power System

Abstract: The quasi-Z-source inverter (qZSI) with battery operation can balance the stochastic fluctuations of photovoltaic (PV) power injected to the grid/load, but its existing topology has a power limitation due to the wide range of discontinuous conduction mode during battery discharge. This paper proposes a new topology of the energy-stored qZSI to overcome this disadvantage. The operating characteristic of the proposed solution is analyzed in detail and compared to that of the existing topology. Two strategies are proposed with the related design principles to control the new energy-stored qZSI when applied to the PV power system. They can control the inverter output power, track the PV panel's maximum power point, and manage the battery power, simultaneously. The voltage boost and inversion, and energy storage are integrated in a single-stage inverter. An experimental prototype is built to test the proposed circuit and the two discussed control methods. The obtained results verify the theoretical analysis and prove the effectiveness of the proposed control of the inverter's input and output powers and battery power regardless of the charging or discharging situation. A real PV panel is used in the grid-tie test of the proposed energy-stored qZSI, which demonstrates three operational modes suitable for application in the PV power system.

System Stability Impact of Large-Scale and Distributed Solar Photovoltaic Generation: The Case of Ontario, Canada

Abstract: This paper presents a comparative investigation of (PV) effect on system stability at different penetration levels. Three different scenarios with their relevant dynamic models are considered, namely, distributed units, and centralized farms with and without voltage regulation capabilities. Based on these models, the impact is examined through eigenvalue, voltage stability and transient stability analyses using real network data pertaining to Ontario and its neighboring systems. This impact is quantized in monetary terms based on the long run marginal cost of electricity production in Ontario. It is demonstrated that distributed solar PV generators are significantly more advantageous, from the stability point of view, than solar farms.

Benchmarking of Grid Fault Modes in Single-Phase Grid-Connected Photovoltaic Systems

Abstract: Pushed by the booming installations of single-phase photovoltaic (PV) systems, the grid demands regarding the integration of PV systems are expected to be modified. Hence, the future PV systems should become more active with functionalities of low-voltage ride through and grid support capability. The control methods, together with grid synchronization techniques, are responsible for the generation of appropriate reference signals in order to handle ride-through grid faults. Thus, it is necessary to evaluate the behaviors of grid synchronization methods and control possibilities in single-phase systems under grid faults. The intent of this paper is to present a benchmarking of grid fault modes that might come in future single-phase PV systems. In order to map future challenges, the relevant synchronization and control strategies are discussed. Some faulty modes are studied experimentally and provided at the end of this paper. It is concluded that there are extensive control possibilities in single-phase PV systems under grid faults. The second-order-general-integral-based phase-locked-loop technique might be the most promising candidate for future single-phase PV systems because of its fast adaptive-filtering characteristics and it is able to fulfill future standards.

Implemental Control Strategy for Grid Stabilization of Grid-Connected PV System Based on German Grid Code in Symmetrical Low-to-Medium Voltage Network

Abstract: In the last couple of years, the increasing penetration of renewable energy resulted in the development of grid-connected large-scale power plants. However, a high penetration harbors the risk of grid instability if the generating power plants are not able to support the grid. Therefore, grid stabilization, which depends on the system-type or grid of each country, plays an important role and has been strengthened by different grid codes. With this background, VDE-AR-N 4105 for photovoltaic (PV) systems connected to the low-voltage grid and the German Association of Energy and Water Industries (BDEW) introduced the medium-voltage grid code for connecting power plants to the grid and they are the most stringent certifications. In this paper, the control strategy of generating system is enhanced with VDE-AR-N 4105 and BDEW grid code, where both active/reactive powers are controlled. Simulation and experimental results of 100-kW PV inverter are shown to verify the effectiveness of the proposed implemental control strategy.

A Fast Current-Based MPPT Technique Employing Sliding Mode Control

Abstract: This paper introduces a novel maximum power point tracking (MPPT) technique aimed at maximizing the power produced by photovoltaic (PV) systems. The largest part of the MPPT approaches presented in the literature are based on the sensing of the PV generator voltage. On the contrary, in this paper, a current-based technique is proposed: the sensing of the current in the capacitor placed in parallel with the PV source is one of the innovative aspects of the proposal. A dual control technique based on an inner current loop plus an outer voltage loop allows to take profit of the fast current tracking capability of the inner current loop while the voltage loop benefits from the logarithmic dependency of the PV voltage on the irradiation level. The features of the proposed algorithm, particularly in terms of tracking of irradiation variations and disturbance rejection, are supported by theoretical analysis, simulations, and experimental results. The technique described in this paper is patent pending.

Small Signal Stability Assessment of Power Systems With Increased Penetration of Photovoltaic Generation: A Case Study

Abstract: The present paper investigates the effect of high penetration of photovoltaic (PV) systems on the small signal stability of a large power system. Reduced system inertia and altered power flow patterns as a result of the addition of the utility scale and residential rooftop PVs that replace a portion of conventional generation resources, may lead to decreased damping of the critical modes of the system. To identify the critical modes of the system and the effect of the high PV penetration on these modes, eigenvalue analysis is carried out on the aforementioned system under various PV penetration levels. To substantiate the results observed from the small signal analysis, transient analysis is carried out on the system under various PV penetration levels. The simulation results effectively identify the impact of high PV penetration on small signal stability of the studied system.

Steady-State Analysis of Maximum Photovoltaic Penetration Levels on Typical Distribution Feeders

Abstract: This paper presents simulation results for a taxonomy of typical distribution feeders with various levels of photovoltaic (PV) penetration. For each of the 16 feeders simulated, the maximum PV penetration that did not result in a steady-state voltage or current violation is presented for several PV location scenarios: clustered near the feeder source, clustered near the midpoint of the feeder, clustered near the end of the feeder, randomly located, and evenly distributed. In addition, the maximum level of PV is presented for single, large PV systems at each location. Maximum PV penetration was determined by requiring that feeder voltages stay within ANSI Range A and that feeder currents stay within the ranges determined by overcurrent protection devices. Generation ramp rates, protection and coordination, and other factors that may impact maximum PV penetrations are not considered here. Simulations were run in GridLAB-D using hourly time steps over a year with randomized load profiles based on utility data and typical meteorological year weather data. For 86% of the 336 cases simulated, maximum PV penetration was at least 30% of peak load.

A review of photovoltaic systems size optimization techniques

Abstract: Based on the fact that PV systems are clean, environment friendly and secure energy sources, PV system installation has played an important role worldwide. However, the drawback of PV system is the high capital cost as compared to conventional energy sources. Currently, many research works are carried out focusing on optimization of PV systems so that the number of PV modules, capacity of storage battery, capacity of inverter, wind turbine capacity as well as diesel generator size optimally selected. In this paper, the current status of research on PV systems size optimization is reviewed taking into account standalone PV systems, hybrid PV/diesel generator systems, hybrid PV/wind systems, hybrid PV/wind/diesel generator systems as well as grid connected systems. In addition, size optimization techniques for the inverter in PV systems are reviewed. The outcome of this paper shows that the optimization of PV system is strongly depends on meteorological variables such as solar energy, ambient temperature and wind speed. Furthermore, the numerical methods are the mostly used methods. Meanwhile the artificial intelligence techniques have been employed recently to improve the process of PV system size optimization.

Fuzzy Control of Distributed PV Inverters/Energy Storage Systems/Electric Vehicles for Frequency Regulation in a Large Power System

Abstract: This paper presents a fuzzy based frequency control strategy by the Megawatt (MW) class distributed PV systems and electric vehicles (EVs). The frequency control is proposed from the view point of the frequency fluctuation problem produced by the large penetration of PV power and sudden load variation. The fuzzy based frequency control has three inputs: average insolation, change of insolation and frequency deviation. Following these three inputs, a frequency control system for the distributed PV inverters is proposed. For the case of different insolations in the different areas of the power system, a coordinated control method of the distributed PV inverters, energy storage systems (ESSs) and EVs is presented. The proposed method is simulated by considering dual power and information flows between supply and demand sides in a large power system and is found satisfactory to provide frequency control and to reduce tie-line power fluctuations.

Mitigation of Solar Irradiance Intermittency in Photovoltaic Power Systems With Integrated Electric-Vehicle Charging Functionality

Abstract: Mitigation of the variability in output power of renewable generators such as solar photovoltaic (PV) systems is a growing concern as these generators reach higher penetrations on electric grids. Furthermore, increased penetration of electric vehicle (EV) loads presents a challenge for distribution feeders. This paper presents a system where a bidirectional, highly efficient, dc-dc EV charger is placed between the high-voltage dc bus of a PV inverter and the EV battery. The system partially alleviates feeder overloading by providing fast charging for the EV battery from the PV system. In addition, the charger is capable of diverting fast changes in PV power output to the battery, thereby reducing the rate of change of inverter output power to a level below the ramp rate of existing grid resources. The paper addresses sizing of the charger and energy storage based on the PV system rating, the desired maximum ramp rate, and site solar irradiation characteristics, including geographic dispersion of PV arrays. Analysis suggests that small amounts of energy storage can accomplish large reductions in output power ramp rate. Experimental results are shown for a 10 kW, 98% efficient dc-dc charger based on bidirectional four-phase zero-voltage-switching converter.

Evaluation of Storage Energy Requirements for Constant Production in PV Power Plants

Abstract: This paper analyzes the minimum energy capacity ratings that an energy-storage (ES) system should accomplish in order to achieve a defined constant power production in a photovoltaic (PV) power plant. ES is a key issue for the further integration of intermittent and stochastic renewable energy sources, which are not currently dispatchable due to their dependence on real-time weather conditions, as is the case of PV technology. This paper proposes and describes an energy management strategy (EMS) for operating PV power plants with ES in the future. The goal of this EMS is to endow these power plants with a constant production that can be controlled and hence traded on electricity markets. This paper presents simulated results on the percentage of time throughout the year during which a large-scale PV+ES plant operates properly with different ES ratings and according to different configurations of this EMS. Finally, a test bench was developed, and experimental results validating this EMS were obtained.

Single-Phase Single-Stage Transformer less Grid-Connected PV System

Abstract: In this paper, a single-phase, single-stage current source inverter-based photovoltaic system for grid connection is proposed. The system utilizes transformer-less single-stage conversion for tracking the maximum power point and interfacing the photovoltaic arrays to the grid. The maximum power point is maintained with a fuzzy logic controller. A proportional-resonant controller is used to control the current injected into the grid. To improve the power quality and system efficiency, a double-tuned parallel resonant circuit is proposed to attenuate the second- and fourth- order harmonics at the inverter dc side. A modified carrier-based modulation technique for the current source inverter is proposed to magnetize the dc-link inductor by shorting one of the bridge converter legs after every active switching cycle. Simulation and practical results validate and confirm the dynamic performance and power quality of the proposed system.