A Single-Stage Grid Connected Inverter Topology for Solar PV Systems With Maximum Power Point Tracking
TL;DR: In this article, the authors proposed a high performance single-stage inverter topology for grid connected PV systems, which can not only boost the usually low photovoltaic (PV) array voltage, but can also convert the solar dc power into high quality ac power for feeding into the grid, while tracking the maximum power from the PV array.
Abstract: This paper proposes a high performance, single-stage inverter topology for grid connected PV systems. The proposed configuration can not only boost the usually low photovoltaic (PV) array voltage, but can also convert the solar dc power into high quality ac power for feeding into the grid, while tracking the maximum power from the PV array. Total harmonic distortion of the current, fed into the grid, is restricted as per the IEEE-519 standard. The proposed topology has several desirable features such as better utilization of the PV array, higher efficiency, low cost and compact size. Further, due to the very nature of the proposed topology, the PV array appears as a floating source to the grid, thereby enhancing the overall safety of the system. A survey of the existing topologies, suitable for single-stage, grid connected PV applications, is carried out and a detailed comparison with the proposed topology is presented. A complete steady-state analysis, including the design procedure and expressions for peak device stresses, is included. Necessary condition on the modulation index "M" for sinusoidal pulsewidth modulated control of the proposed inverter topology has also been derived for discontinuous conduction mode operation. All the analytical, simulation and experimental results are presented.
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TL;DR: In this article, the authors proposed an improved maximum power point tracking (MPPT) method for the photovoltaic (PV) system using a modified particle swarm optimization (PSO) algorithm.
Abstract: This paper proposes an improved maximum power point tracking (MPPT) method for the photovoltaic (PV) system using a modified particle swarm optimization (PSO) algorithm. The main advantage of the method is the reduction of the steady- state oscillation (to practically zero) once the maximum power point (MPP) is located. Furthermore, the proposed method has the ability to track the MPP for the extreme environmental condition, e.g., large fluctuations of insolation and partial shading condition. The algorithm is simple and can be computed very rapidly; thus, its implementation using a low-cost microcontroller is possible. To evaluate the effectiveness of the proposed method, MATLAB simulations are carried out under very challenging conditions, namely step changes in irradiance, step changes in load, and partial shading of the PV array. Its performance is compared with the conventional Hill Climbing (HC) method. Finally, an experimental rig that comprises of a buck-boost converter fed by a custom-designed solar array simulator is set up to emulate the simulation. The soft- ware development is carried out in the Dspace 1104 environment using a TMS320F240 digital signal processor. The superiority of the proposed method over the HC in terms of tracking speed and steady-state oscillations is highlighted by simulation and experimental results.
851 citations
Cites background from "A Single-Stage Grid Connected Inver..."
...these techniques are not fully adaptive and hence are not very effective [14]....
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TL;DR: In this article, a design example is presented by experimental implementation of the proposed technique and practical results for the implemented setup at different irradiance levels are illustrated to validate the proposed scheme.
Abstract: Solar photovoltaic (PV) energy has witnessed double-digit growth in the past decade. The penetration of PV systems as distributed generators in low-voltage grids has also seen significant attention. In addition, the need for higher overall grid efficiency and reliability has boosted the interest in the microgrid concept. High-efficiency PV-based microgrids require maximum power point tracking (MPPT) controllers to maximize the harvested energy due to the nonlinearity in PV module characteristics. Perturb and observe (PO second, no steady-state oscillations around the MPP; and lastly, no need for predefined system-dependent constants, hence provides a generic design core. A design example is presented by experimental implementation of the proposed technique. Practical results for the implemented setup at different irradiance levels are illustrated to validate the proposed technique.
774 citations
TL;DR: In this article, a comprehensive review of step-up single-phase non-isolated inverters suitable for ac-module applications is presented, where the selected solutions are designed and simulated complying with the benchmark obtaining passive and semiconductor components ratings.
Abstract: This paper presents a comprehensive review of step-up single-phase non-isolated inverters suitable for ac-module applications. In order to compare the most feasible solutions of the reviewed topologies, a benchmark is set. This benchmark is based on a typical ac-module application considering the requirements for the solar panels and the grid. The selected solutions are designed and simulated complying with the benchmark obtaining passive and semiconductor components ratings in order to perform a comparison in terms of size and cost. A discussion of the analyzed topologies regarding the obtained ratings as well as ground currents is presented. Recommendations for topological solutions complying with the application benchmark are provided.
475 citations
Cites methods from "A Single-Stage Grid Connected Inver..."
...The same principle and operation mode is applied to the topologies introduced in [47] and [48]....
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...Buck–boost-based single-stage inverter [48]....
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TL;DR: In this article, a grid-connected photovoltaic (PV) power system with high voltage gain is proposed, and the steady-state model analysis and the control strategy of the system are presented.
Abstract: A grid-connected photovoltaic (PV) power system with high voltage gain is proposed, and the steady-state model analysis and the control strategy of the system are presented in this paper. For a typical PV array, the output voltage is relatively low, and a high voltage gain is obligatory to realize the grid-connected function. The proposed PV system employs a ZVT-interleaved boost converter with winding-coupled inductors and active-clamp circuits as the first power-processing stage, which can boost a low voltage of the PV array up to a high dc-bus voltage. Accordingly, an accurate steady-state model is obtained and verified by the simulation and experimental results, and a full-bridge inverter with bidirectional power flow is used as the second power-processing stage, which can stabilize the dc-bus voltage and shape the output current. Two compensation units are added to perform in the system control loops to achieve the low total harmonic distortion and fast dynamic response of the output current. Furthermore, a simple maximum-power-point-tracking method based on power balance is applied in the PV system to reduce the system complexity and cost with a high performance. At last, a 2-kW prototype has been built and tested to verify the theoretical analysis of the paper.
468 citations
01 Sep 2007
TL;DR: In this article, the authors compared three transformerless photovoltaic inverter topologies for three-phase grid connection with the main focus on the safety issues that result from the lack of galvanic isolation.
Abstract: This paper analyzes and compares three transformerless photovoltaic inverter topologies for three-phase grid connection with the main focus on the safety issues that result from the lack of galvanic isolation. A common-mode model, valid at frequencies lower than 50 kHz, is adopted to study the leakage current paths. The model is validated by both simulation and experimental results. These will be used to compare the selected topologies, and to explain the influence of system unbalance and the neutral conductor inductance on the leakage current. It will be demonstrated that the later has a crucial influence. Finally, a comparison of the selected topologies is carried out, based on the adopted modulation, connection of the neutral and its inductance, effects of unbalance conditions, component ratings, output voltage levels, and filter size.
455 citations
Cites methods from "A Single-Stage Grid Connected Inver..."
...A suitable Maximum Power Point Tracking algorithm (MPPT) [6] (shown in Fig....
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References
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TL;DR: In this article, the authors focus on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid and categorize the inverters into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single phase grid; 3) whether they utilizes a transformer (either line or high frequency) or not; and 4) the kind of grid-connected power stage.
Abstract: This review focuses on inverter technologies for connecting photovoltaic (PV) modules to a single-phase grid. The inverters are categorized into four classifications: 1) the number of power processing stages in cascade; 2) the type of power decoupling between the PV module(s) and the single-phase grid; 3) whether they utilizes a transformer (either line or high frequency) or not; and 4) the type of grid-connected power stage. Various inverter topologies are presented, compared, and evaluated against demands, lifetime, component ratings, and cost. Finally, some of the topologies are pointed out as the best candidates for either single PV module or multiple PV module applications.
3,530 citations
"A Single-Stage Grid Connected Inver..." refers background in this paper
...A local earth, created for the grounding of the PV array, will suffice [12]....
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...On the other hand, a PV array with large dc voltage suffers from drawbacks such as hot-spots during partial shading of the array, reduced safety and increased probability of leakage current through the parasitic capacitance between the panel and the system ground [11], [12]....
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TL;DR: In this article, power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems.
Abstract: The global electrical energy consumption is rising and there is a steady increase of the demand on the power capacity, efficient production, distribution and utilization of energy. The traditional power systems are changing globally, a large number of dispersed generation (DG) units, including both renewable and nonrenewable energy sources such as wind turbines, photovoltaic (PV) generators, fuel cells, small hydro, wave generators, and gas/steam powered combined heat and power stations, are being integrated into power systems at the distribution level. Power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems. This paper reviews the applications of power electronics in the integration of DG units, in particular, wind power, fuel cells and PV generators.
2,296 citations
"A Single-Stage Grid Connected Inver..." refers background in this paper
...), reduced weight and low cost [11]–[14]....
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...On the other hand, a PV array with large dc voltage suffers from drawbacks such as hot-spots during partial shading of the array, reduced safety and increased probability of leakage current through the parasitic capacitance between the panel and the system ground [11], [12]....
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Journal Article•
TL;DR: In this article, power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems.
Abstract: The global electrical energy consumption is rising and there is a steady increase of the demand on the power capacity, efficient production, distribution and utilization of energy. The traditional power systems are changing globally, a large number of dispersed generation (DG) units, including both renewable and nonrenewable energy sources such as wind turbines, photovoltaic (PV) generators, fuel cells, small hydro, wave generators, and gas/steam powered combined heat and power stations, are being integrated into power systems at the distribution level. Power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems. This paper reviews the applications of power electronics in the integration of DG units, in particular, wind power, fuel cells and PV generators.
2,076 citations
TL;DR: In this paper, an overview of single-phase inverters developed for small distributed power generators is presented, compared, and evaluated against the requirements of power decoupling and dual-grounding, the capabilities for grid-connected or/and stand-alone operations, and specific DG applications.
Abstract: This paper presents an overview of single-phase inverters developed for small distributed power generators. The functions of inverters in distributed power generation (DG) systems include dc-ac conversion, output power quality assurance, various protection mechanisms, and system controls. Unique requirements for small distributed power generation systems include low cost, high efficiency and tolerance for an extremely wide range of input voltage variations. These requirements have driven the inverter development toward simpler topologies and structures, lower component counts, and tighter modular design. Both single-stage and multiple-stage inverters have been developed for power conversion in DG systems. Single-stage inverters offer simple structure and low cost, but suffer from a limited range of input voltage variations and are often characterized by compromised system performance. On the other hand, multiple-stage inverters accept a wide range of input voltage variations, but suffer from high cost, complicated structure and low efficiency. Various circuit topologies are presented, compared, and evaluated against the requirements of power decoupling and dual-grounding, the capabilities for grid-connected or/and stand-alone operations, and specific DG applications in this paper, along with the identification of recent development trends of single-phase inverters for distributed power generators.
899 citations
"A Single-Stage Grid Connected Inver..." refers background in this paper
...(a)–(g): Schematic circuit diagrams of the various existing single-stage topologies [15]–[18], [20]–[22], [25] and (h) proposed scheme....
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01 Jan 2001
TL;DR: In this paper, an accurate PV module electrical model based on the Shockley diode equation is presented, which has a photo-current current source, a single diode junction and a series resistance, and includes temperature dependences.
Abstract: An accurate PV module electrical model is presented based on the Shockley diode equation. The simple model has a photo-current current source, a single diode junction and a series resistance, and includes temperature dependences. The method of parameter extraction and model evaluation in Matlab is demonstrated for a typical 60W solar panel. This model is used to investigate the variation of maximum power point with temperature and isolation levels. A comparison of buck versus boost maximum power point tracker (MPPT) topologies is made, and compared with a direct connection to a constant voltage (battery) load. The boost converter is shown to have a slight advantage over the buck, since it can always track the maximum power point.
896 citations