scholarly journals Step-Down Partial Power DC-DC Converters for Two-Stage Photovoltaic String Inverters

Electronics ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 87 ◽  
Author(s):  
Jaime Zapata ◽  
Samir Kouro ◽  
Gonzalo Carrasco ◽  
Thierry Meynard
Keyword(s):  
Large Scale ◽  
Power Converter ◽  
Point Of View ◽  
Single Stage ◽  
Pv System ◽  
Voltage Step ◽  
Point Tracking ◽  
Pv Modules ◽  
Step Down ◽  
Conversion Stage

Photovoltaic (PV) systems composed by two energy conversion stages are attractive from an operation point of view. This is because the maximum power point tracking (MPPT) range is extended, due to the voltage decoupling between the PV system and the dc-link. Nevertheless, the additional dc-dc conversion stage increases the volume, cost and power converter losses. Therefore, central inverters based on a single-stage converter, have been a mainstream solution to interface large-scale PV arrays composed of several strings connected in parallel made by the series connections of PV modules. The concept of partial power converters (PPC), previously reported as a voltage step-up stage, has not addressed in depth for all types of PV applications. In this work, a PPC performing voltage step-down operation is proposed and analyzed. This concept is interesting from the industry point of view, since with the new isolation standards of PV modules are reaching 1500 V, increasing both the size of the string and dc-link voltage for single-stage inverters. Since grid connection remains typically at 690 V, larger strings impose more demanding operation for single-stage central inverters (required to operate at lower modulation indexes and demand higher blocking voltage devices), making the proposed step-down PPC an attractive solution. Theoretical analysis and an experimental test-bench was built in order to validate the PPC concept, the control performance and the improvement of the conversion efficiency. The experimental results corroborate the benefits of using a PPC, in terms of increasing the system efficiency by reducing the processed power of the converter, while not affecting the system performance.

scholarly journals Power dissipation analysis of PV module under partial shading

2021 ◽  
Vol 11 (2) ◽  
pp. 1029
Author(s):  
Byunggyu Yu ◽  
Seok-Cheol Ko
Keyword(s):  
Power Dissipation ◽  
Input Voltage ◽  
Maximum Power ◽  
Pv System ◽  
Partial Shading ◽  
Point Tracking ◽  
Pv Inverter ◽  
Pv Module ◽  
Pv Modules ◽  
Total Maximum

Photovoltaic (PV) generation has been growing dramatically over the last years and it ranges from small, rooftop-mounted or building integrated systems, to large utility scale power stations. Especially for rooftop-mounted PV system, PV modules are serially connected to match with PV inverter input voltage specification. For serially connected PV system, shading is a problem since the shaded PV module reduces the output whole string of PV modules. The excess power from the unshaded PV module is dissipated in the shaded PV module. In this paper, power dissipation of PV module under partial shading is analyzed with circuit analysis for series connected PV modules. The specific current and voltage operating point of the shaded PV module are analyzed under shading. PSIM simulation tool is used to verify the power dissipation analysis. When there is no bypass diode and three solar modules are connected in series, upto 39.1% of the total maximum PV power is dissipated in the shaded PV module. On the other hand, when the bypass is attached, 0.3% of the total maximum power is generated as a loss in the shaded PV module. The proposed analysis technique of shaded PV module could be used in PV system performance analysis, especially for maximum power point tracking (MPPT) performance.

scholarly journals A Novel Algorithm for MPPT of an Isolated PV System Using Push Pull Converter with Fuzzy Logic Controller

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 4007 ◽  
Author(s):  
Tehzeeb-ul Hassan ◽  
Rabeh Abbassi ◽  
Houssem Jerbi ◽  
Kashif Mehmood ◽  
Muhammad Faizan Tahir ◽  
...  
Keyword(s):  
Fuzzy Logic ◽  
Fuzzy Logic Controller ◽  
Harmonic Distortion ◽  
Pv System ◽  
Dynamic Simulations ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Point Tracking ◽  
Dc Gain ◽  
Pv Modules

Photovoltaic (PV) is a highly promising energy source because of its environment friendly property. However, there is an uncertainty present in the modeling of PV modules owing to varying irradiance and temperature. To solve such uncertainty, the fuzzy logic control-based intelligent maximum power point tracking (MPPT) method is observed to be more suitable as compared with conventional algorithms in PV systems. In this paper, an isolated PV system using a push pull converter with the fuzzy logic-based MPPT algorithm is presented. The proposed methodology optimizes the output power of PV modules and achieves isolation with high DC gain. The DC gain is inverted into a single phase AC through a closed loop fuzzy logic inverter with a low pass filter to reduce the total harmonic distortion (THD). Dynamic simulations are developed in Matlab/Simulink by MathWorks under linear loads. The results show that the fuzzy logic algorithms of the proposed system efficiently track the MPPT and present reduced THD.

scholarly journals Design & Simulation of Flexible Control For 3-phase Grid Connected Solar PV System

2018 ◽  
Vol 7 (2.25) ◽  
pp. 148
Author(s):  
R. Srinivasan ◽  
C. R.Balamurugan ◽  
N. Shanmugasundaram
Keyword(s):  
Large Scale ◽  
Voltage Source ◽  
Control Factor ◽  
Solar Pv ◽  
Pv System ◽  
Flexible Control ◽  
Point Tracking ◽  
Power Point Tracking ◽  
Solar Pv System ◽  
Power Point

A non-linear control progression for 3-stage (phase) lattice (grid) associated of PV generator is proposed here. This system is designed with PV arrays; grid filter; a voltage source inverter and a stimulating lattice or network. The regulator purposes are classified into three sections: i) making sure that the Most power point tracking (MPPT) are having photovoltaic boards, ii) assuring  for power or control factor entity or unit in the grid plane iii) ensuring large-scale asymptotic constancy of the closed loop system. Lyapunov modelling approach is used by the controller and carried out by considering nonlinear model of the integral method. It is formally shown that the projected system controller congregates the scope of the objectives using a hypothetical constancy with stability analysis as well as simulation results.  

scholarly journals A New Generalized Step-Down Single-Stage AC/AC Power Converter

2020 ◽  
Vol 12 (21) ◽  
pp. 9181
Author(s):  
Md. Shihab Uddin ◽  
Shuvra Prokash Biswas ◽  
Md. Rabiul Islam ◽  
Md. Shamim Anower ◽  
Abbas Z. Kouzani ◽  
...  
Keyword(s):  
Pulse Width Modulation ◽  
Power Conversion ◽  
Power Converter ◽  
Single Stage ◽  
Switching Losses ◽  
Multi Stage ◽  
Ac Power ◽  
Modulation Techniques ◽  
Converter Topology ◽  
Step Down

Most traditional AC/AC power converters suffer from power quality problems and multi-stage power conversion losses. The rectifier and inverter-based AC/AC converter topology not only increases multi-stage power conversion losses, but also increases the volume, weight, and cost, and decreases the longevity of the converter due to the DC-link capacitor, line filter and electromagnetic interference (EMI) filter. High-frequency (about 10 kHz) switching advanced pulse width modulation techniques are generally used in order to compensate the power quality problems, which increase the switching losses and introduce the EMI problems. In this paper, a new generalized step-down single-stage line-frequency switching AC/AC power converter topology is proposed. The proposed converter uses line-frequency switching, and does not require any pulse width modulation techniques. The proposed topology offers promising performances in terms of lower order harmonics, total harmonic distortion, the elimination of DC-link capacitors and EMI filters, and switching losses. The circuit was designed and simulated in a MATLAB/Simulink environment. A scaled-down laboratory prototype of the proposed topology was developed in order to validate the feasibility. The experimental and simulation results reveal the feasibility of the proposed generalized step-down single-stage converter topology, and its excellent features.

scholarly journals Parallel PV Configuration with Magnetic-Free Switched Capacitor Module-Level Converters for Partial Shading Conditions

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 456
Author(s):  
Georgios Kampitsis ◽  
Efstratios Batzelis ◽  
Remco van Erp ◽  
Elison Matioli
Keyword(s):  
Fixed Ratio ◽  
Maximum Power ◽  
Switched Capacitor ◽  
Total System ◽  
Pv System ◽  
Partial Shading ◽  
Power Extraction ◽  
Point Tracking ◽  
Dc Bus ◽  
Conversion Stage

In this paper, a module-level photovoltaic (PV) architecture in parallel configuration is introduced for maximum power extraction, under partial shading (PS) conditions. For the first time, a non-regulated switched capacitor (SC) nX converter is a used at the PV-side conversion stage, whose purpose is just to multiply the PV voltage by a fixed ratio and accordingly reduce the input current. All the control functions, including the maximum power point tracking, are transferred to the grid-side inverter. The voltage-multiplied PV modules (VMPVs) are connected in parallel to a common DC-bus, which offers expandability to the system and eliminates the PS issues of a typical string architecture. The advantage of the proposed approach is that the PV-side converter is relieved of bulky capacitors, filters, controllers and voltage/current sensors, allowing for a more compact and efficient conversion stage, compared to conventional per-module systems, such as microinverters. The proposed configuration was initially simulated in a 5 kW residential PV system and compared against conventional PV arrangements. For the experimental validation, a 10X Gallium Nitride (GaN) converter prototype was developed with a flat conversion efficiency of 96.3% throughout the power range. This is particularly advantageous, given the power production variability of PV generators. Subsequently, the VMPV architecture was tested on a two-module 500 WP prototype, exhibiting an excellent power extraction efficiency of over 99.7% under PS conditions and minimal DC-bus voltage variation of 3%, leading to a higher total system efficiency compared to most state-of-the-art configurations.

scholarly journals A Novel MPPT Technique for Single Stage Grid-Connected PV Systems: T4S

Energies ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4501 ◽  
Author(s):  
Costanzo ◽  
Vitelli
Keyword(s):  
Reference Signal ◽  
Average Power ◽  
Single Stage ◽  
Voltage Reference ◽  
Pv System ◽  
Pv Systems ◽  
Point Tracking ◽  
Power Point Tracking ◽  
Perturb And Observe ◽  
Power Point

In this paper, a novel maximum power point tracking (MPPT) technique, which has been named T4S (a technique based on the proper setting of the sign of the slope of the photovoltaic voltage reference signal), is presented and discussed. It is specifically designed with reference to a single-stage grid-connected PV system. Its performance is numerically compared with that of the well-known and widely used perturb and observe (P&O) MPPT technique. The results of the numerical simulations confirm the validity of the proposed MPPT technique which exhibited a slightly better performance, under stationary and also time-varying irradiance conditions. In addition, the T4S technique is characterized by the following features: it does not require explicit power detection or calculation and, moreover, it allows the tracking of the maximum average power injected into the grid rather than the tracking of the maximum instantaneous power extracted by the PV source.

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