Inverter For Photovoltaic Applications Research Articles

Harmonic Stability Assessment of Commercially Available Single-Phase Photovoltaic Inverters Considering Operating-Point Dependencies

The growth of renewables in the energy sector, e.g., in public low-voltage networks, leads to an increasing share of installed power electronic devices, e.g., inverters for photovoltaic applications. To rely on these devices, suitable analyses have to be performed. This includes studies of the device stability in the harmonic frequency range, i.e., above 50 Hz up to 2 kHz. State-of-the-art time-domain studies for harmonic stability analyses require detailed knowledge about the inverter design. Black-box studies must identify the inverter characteristics in the laboratory, which can differ depending on specific operating points, i.e., specific operating powers. This study analyzes the operating-point dependency of inverters on the critical inductance values of the network impedance, e.g., the inductances at which the inverter is expected to become unstable. Measurements are performed for three operating powers of an unknown, commercially available single-phase inverter to validate the critical inductances. Two further commercially available inverters and four simulative implementations are analyzed as well with regard to the critical inductance and the critical frequency. The results demonstrate the importance of considering a representative range of operating powers of the inverter for the small-signal stability analysis.

Reliability Assessment of Hybrid Silicon-Silicon Carbide IGBT Implemented on an Inverter for Photo Voltaic Applications

Reliability Assessment of Hybrid Silicon-Silicon Carbide IGBT Implemented on an Inverter for Photo Voltaic Applications

PI-based ZSVM Control of Quasi-Z-Source Inverter for Photovoltaic Applications in Standalone Mode

The power converters Z-source topology are becoming a promoter solution for the energy conversion. This topology has the ability to boost and convert the voltage in a single-stage, unlike the famous two-stage conventionnel structure. The Quasi-Z-Source Inverter (QZSI) is nowadays the subject of several research works. However, it is the most suitable for PV applications, due to his continuous input current, which allows to harvest the maximum power available from the PV panels. In this regard, this paper investigates the dynamic characteristics of the QZSI through the small signal analysis, as well as the scheme control with the SVPWM technique for QZSI in standalone mode. The simulation results illustrate the practicability and the validity of the control scheme proposed.

An improved energy storage switched boost grid‐connected inverter for photovoltaic applications

When the traditional two-stage boost inverter is used in photovoltaic (PV) and energy storage systems, it is necessary to connect additional bidirectional conversion devices, which will increase the loss of the system and increase the complexity of system control. Therefore, an improved energy storage switched boost (ESSB) grid-connected inverter is proposed in this paper. The system has the advantages of high integration, high gain and dead time immunity. By controlling the duty cycle of the system, the energy management of the battery can be realized. The system consists of three parts: PV cells, ESSB network and grid-connected inverter. In order to maximize the energy utilization, this paper uses the disturbance observation method to track the maximum power point of PV cells, and formulates a set of energy management strategy to control the energy flow between the three energy units. Simulation and experiments verify the superiority of the topology and the feasibility of the energy storage strategy.

Design and control of an improved Z‐H8 inverter for photovoltaic applications

AbstractThis paper proposes a new modified buck–boost converter entitled the basic Z‐H8 topology. The modified configuration is composed by adding two dc decoupling and non‐ideal compensation blocks across the dc‐input side of the conventional Z‐H buck converter. These blocks create some benefits such as buck–boost ability and lower stresses and ripples for passive and active elements by up to 50% compared to the traditional Z‐H structure. Moreover, the proposed topology can be used as a dc/dc, dc/ac, or ac/dc converter. Hence, various control techniques based on unipolar PWM and SPWM are proposed for the basic Z‐H8 configuration to act as an inverter. Other valuable advantages are providing galvanic isolation and reducing leakage current by two blocks, which can be extremely useful for photovoltaic (PV) applications. Thus, a grid‐connected single‐stage PV system with a proper model predictive control algorithm is proposed. Despite a continuous voltage on the Z‐H8 inverter output, other benefits of the proposed PV system are tracking the maximum power point, adjusting the injected powers to the grid, and increasing security and reliability. The operating principle of the proposed topologies and control methods are explained in detail with the relevant equations and are confirmed by the simulation and experimental results.

Trends and Challenges in Grid-Tied Inverters for Photovoltaic Applications

Grid-Tied inverter has gained the attention of many researchers and power generation industry due to its capability of integrating distributed power generation systems using renewable energy resources with the existing centralized power generation system. Yet the inclusion of a transformer in the Photovoltaic (PV) inverter makes it bulkier, heavier and more expensive. A primary solution to the aforementioned problems is the transformerless PV Grid-Tied inverter. This paper presents a review of different transformerless, single-phase Grid-Tied inverter topologies. The objective of this paper is to study parameters such as leakage current, common-mode voltage, total harmonic distortion, and the efficiency of transformerless Grid-Tied inverters. The paper also provides a discussion on existing Grid-Tied inverter topologies, such as H5, oH5, Novel H5, H5-D, FBDC, H6D2, Hybrid H6, High-efficiency MOSFET H6, Improved H6, 3L H6, H6-A, B, High-Efficiency H6, H6-N, Improved H6, H6-active clamping, Active clamped snubber based H6, Heric, oHeric, Enhanced Heric, Heric-with mid-DC-link, Active clamping, PN-NPC, Improved FBNPC, T-Type 3L, ANPC, HBNPC, NIFB-NPCI, VNIIFBC, M-NPC, Virtual DC bus based inverter, Active Virtual Ground, Type I, Type II, Type III Common Ground, Flying Capacitor and Multilevel Common Ground. Though it is found that many topologies available in the literature, other new topologies can be proposed to improve the performance of the inverter. Furthermore, it is also noted that the performance analysis of the inverter must be carried out in the presence of junction capacitance and shoot-through problem so that new strategies can be introduced in the existing typologies to address these issues.

RETRACTED ARTICLE: Improved diode assisted voltage fed three phase quasi z-source inverter for photovoltaic application

In this paper, we propose a design and simulation of improved diode assisted voltage fed three phase quasi z-source inverter for photovoltaic application. Variable shoot through time interval is generated by adding low frequency voltage with constant voltage and the control signal for variable shoot is generated using boost PWM control. The output quality of three phase QZSI is improved by replacing the diode with active power switch in Switch Boost Inverter (SBI). Additionally, we use fuzzy logic controller for optimizing the shoot through duty ratio and modulation index from the source side rectifier, which increases the gain of three phase QZSI. The proposed topology in photovoltaic application increases the input voltage gain and voltage boost property by reducing the number of components, voltage ratings and stress across the switches in three phase QZSI. The proposed method enables improved voltage gain in single stage conversion, which is used for boost function. The simulation of proposed photovoltaic model is built on Simulink. Performance of proposed is evaluated against various metrics including power consumption, delay and power delay product and it is compared against existing VSI.

System Model and Performance Evaluation of Single-Stage Buck–Boost-Type Manitoba Inverter for PV Applications

This article presents a control methodology for a recently proposed single-stage buck–boost-type inverter in photovoltaic (PV) applications. A wide range of input voltage is covered, and the dc power is effectively converted into the grid power within a single-stage system. However, from the topological characteristics, a ${ C\!L}$ filter is always formed at the system output, which results in a resonance pole in the control system. In the PV system, the panel output voltage keeps varying. Under the traditional control method, stability issues may occur, which poses a challenge to controller design. Thus, targeting PV applications, a comprehensive control methodology is presented in this article. Under such a control scheme, a high-quality ac grid power is guaranteed and the power conversion is maintained in a stable manner. Meanwhile, the maximum power point (MPP) of PV panels is always tracked and no additional current sensor is required in the MPP tracking (MPPT) design. In this article, a detailed system analysis is presented, which includes the system modeling and the stability evaluation. The performance of the presented control methodology is experimentally verified in a 750-W PV inverter platform. Both steady state and dynamic characteristics are in good agreement with theoretical knowledge.

Experimental Comparison of Two-Level Full-SiC and Three-Level Si–SiC Quasi-Z-Source Inverters for PV Applications

The paper presents a comparative study of two solar string inverters based on the Quasi-Z-Source (QZS) network. The first solution comprises a full-SiC two-level QZS inverter, while the second design was built based on a three-level neutral-point-clamped QZS inverter with Silicon based Metal–Oxide–Semiconductor Field-Effect Transistors (Si MOSFETs). Several criteria were taken into consideration: the size of passive elements, thermal design and size of heatsinks, voltage stress across semiconductors, and efficiency investigation. The Photovoltaic (PV)-string rated at 1.8 kW power was selected as a case study system. The advantages and drawbacks of both solutions are presented along with conclusions.

Design and Implementation of Analog Controller Based Single Phase Full Bridge Inverter for Photovoltaic Applications

This paper presents a low-cost design of the analog controller for the photovoltaic driven single-phase inverter to generate desired output voltage. The hardware set-up mainly consists of an inverter and an analog controller. The developed controller controls the output voltage of the inverter using SPWM (Sinusoidal Pulse Width Modulation) technique. The inverter, which is designed using Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) as a switch, generates high-quality output with reduced ripple content and less filtering requirement, making the whole setup cost-effective and efficient. A gate driver circuit is also employed to provide isolation between the inverter and the analog controller. The closed loop analog controller for the photovoltaic driven inverter is implemented and tested for various loads. In all these cases, the output voltage waveforms are of high quality with a lesser number of lower order harmonics. In this way, the paper presents a low-cost design of the inverter that can be used for low-power domestic applications. Citation: Ranjan, A., Jalutharia, S., GARG, H., and Gupta, N. (2018). Design and Implementation of Analog Controller Based Single Phase Full Bridge Inverter for Photovoltaic Applications. Trends in Renewable Energy, 4, 102-113. DOI: 10.17737/tre.2018.4.3.0069

Analysis of transformer less inverter for PV applications

To enhance the effectiveness and decrease the cost of a Photovoltaic (PV) system, the utilization of transformer less PV inverters is an option of expanding interest. In any case, this topology should be considered in detail, as it shows a few issues like effectiveness degradation and safety issues identified with the galvanic association between the system and the PV generator.In this research paper, a review of standalone and grid-connected PV inverter structures has been done. From one viewpoint, a few options in light of established structures have been introduced. At last parasitic capacitance in PV arrays and leakage current produced from PV systems are examined.

Experimental Implementation of a Low-Cost Single Phase Five-Level Inverter for Autonomous PV System Applications Without Batteries

This paper presents the design and the implementation of a low-cost single phase five-level inverter for photovoltaic applications. The proposed multilevel inverter is composed of a simple boost converter, a switched-capacitor converter, and an H-bridge converter. An efficient control method which associates a closed-loop regulation method with a simple maximum power point tracking (MPPT) method is applied in order to allow the proposed multilevel inverter to transfer power energy from solar panels to autonomous load with no storage batteries. An experimental prototype of this inverter is fabricated at the laboratory and tested with a digital control system. Obtained results confirm the simplicity and the performance of the proposed photovoltaic system.

Analysis of Current Harmonics Compensation and the Effect of Frequency Variation for Single-Phase Stand-Alone PV Inverters using PR Controller

ABSTRACTThis paper presents the analysis of current harmonics compensation using the proportional-resonant controller for single-phase stand-alone photovoltaic inverter applications. The effect of frequency variation in the reference signal to the controller performance was also analyzed. The controller parameters (Kp, Ki, and ωc) and the inductor-capacitor (LC)-filter parameters are optimally selected to obtain a very low current total harmonic distortion . The control algorithm was implemented using a low-cost digital signal processor (DSP) TMS320F28335 eZdsp development board. Both simulation and experimental results validate the performance and the effectiveness of the control technique used.

A comparison of quasi-Z-source inverters and conventional two-stage inverters for PV applications

This paper presents a comparative study between the single-stage quasi-Z-source inverter (qZSI) and the conventional two-stage inverter for Photovoltaic (PV) applications based on an filed programmable gate array (FPGA). The comparison is conducted in terms of the voltage stress on the inverter switches, the required active and passive components, the transient and the steady state performances, and the inverters efficiency. The modelling, the theoretical concepts, and the control design for both inverters are presented and discussed. Moreover, the passive components requirement and the inverters losses analysis are introduced. Experimental investigations are conducted to verify the proposed inverter. It is noted that the qZSI shows a lower voltage stress on the inverter switches than the conventional two-stage inverter when the inverter gain up to 2. The results also demonstrate that the transient and the steady state performances of qZSI are comparable with the ones of the two-stage inverter under the same operating conditions. However, the qZSI shows lower THD values which in turn result in a reduced output filter size and cost. Additionally, the efficiency test is done based on calculations and real measurements for both inverters. The results point out that the qZSI shows higher efficiency than the conventional solution. Based on these observations, the qZSI proposes an attractive alternative for PV applications.

Digital Control of Photovoltaic based Multilevel Converter for Improved Harmonic Performance

Objectives: In the last two decades, various control algorithms have been proposed for several multilevel converter topologies each having their pros and cons compared with improvement in harmonic performance and efficiency. The multicarrier modulation strategy seems to be the most common thread for multilevel topologies. Methods/Statistical Analysis: The harmonic observations for phase shifted and phase disposition multicarrier strategy is different for cascaded and neutral point clamped topologies. The exemplification of mathematical analysis and hardware in loop results with Nexys 4 FPGA digital controller with Xilinx and MATLAB/Simulink for digital control modulation of Marx multilevel inverter for photovoltaic application is discussed. Findings: The balanced charging and discharging of the capacitor will lead to less leakage current, further reducing the health hazards to the working personals in the region. The analysis and implementation of the most suitable carrier based control strategy technique show superiority over the harmonic content for different techniques for the aforementioned topology. The hardware results show the similarity with the simulated version with comparison with pre-existing topologies. Application/Improvements: The paper discusses the application with real-time hardware photovoltaic implementation of self-boost capable Marx multilevel inverter with an added advantage of equalization with capacitor charge. An improved total harmonic distortion evaluation with preexisting topologies is presented.

Thirteen-level inverter for photovoltaic applications

With the recent cost reduction and efficiency improvement of solar photovoltaic (PV) cells, there is a growing interest towards PV systems in different applications. One promising application is solar PV powered electric vehicles. When they are moving on roads, the whole or some parts of the PV system might be shaded by trees, high buildings, etc.; which result in non-uniform insolation conditions. As a remedial measure, this paper presents a development of a cascaded multi-level inverter based PV system for electric vehicle applications. The basic architecture and switching of the converter switches are described. A laboratory prototype of the proposed architecture was implemented using MOSFETs and harmonic performance under different shading conditions was evaluated. It was found, that under shaded conditions, the 3rd harmonic content can increase and that it depends on the number of modules shaded and the loading condition. The shading performance, losses and power utilization of the cascaded multi-level inverter are compared with that of a conventional Pulse Width Modulated (PWM) inverter architecture. The proposed inverter shows better immunity for shading than a PWM inverter. Furthermore, it was found that the switching losses of the proposed inverter are one 10th to one 20th of that of a PWM inverter. Additionally, by properly selecting the switches, it is also possible to reduce the conduction losses compared to that of a PWM inverter. Even though the power utilization is compromised at full insolation, the power utilization performance of the proposed inverter is superior under shading conditions, thus ideally suited for the selected application. As the modular nature of the proposed inverter allows cascading of more H-bridges with fewer cells, the harmonic, shading, loss and power utilization performance of the proposed inverter can be enhanced with more number of steps in the output waveform.

A Comparative Study of Cascaded Z-Source and Quasi Z-Source Multilevel Inverter for Photovoltaic applications

A Comparative Study of Cascaded Z-Source and Quasi Z-Source Multilevel Inverter for Photovoltaic applications

Prediction of Bond Wire Fatigue of IGBTs in a PV Inverter under a Long-Term Operation

Bond wire fatigue is one of the dominant failure mechanisms in insulated-gate bipolar transistor (IGBT) modules under cyclic stresses. However, there are still major challenges ahead to achieve a realistic bond wire lifetime prediction in field operation. This paper proposes a Monte Carlo based analysis method to predict the lifetime consumption of bond wires of IGBT modules in a photovoltaic (PV) inverter. The variations in IGBT parameters (e.g., on-state collector-emitter voltage), lifetime models, and environmental and operational stresses are taken into account in the lifetime prediction. The distribution of the annual lifetime consumption is estimated based on a long-term annual stress profile of solar irradiance and ambient temperature. The proposed method enables a more realistic lifetime prediction with a specified confidence level compared to the state-of-the-art approaches. A study case of IGBT modules in a 10-kW three-phase PV inverter is given to demonstrate the procedure of the method. The obtained results of the lifetime distribution can be used to justify the selection of IGBTs for the PV inverter applications and the corresponding risk of unreliability.

A new cascade boost inverter for photovoltaic applications with minimum number of elements

Summary Photovoltaic systems consist of a DC-DC converter that can track the peak power operating point and a DC-AC inverter to deliver the active power into the utility. In this paper, a novel cascade boost inverter for photovoltaic application is presented which requires fewer number of power electronic elements. The number of required switches and gate driver circuits against required output voltage levels is a very important factor in designing of an inverter because switches define the circuit size, reliability, losses, costs and control complexity. The comparison of the proposed structure with other new structures and classical multilevel inverters is presented to reflect the merits of the presented structure. The operation of the proposed inverter is analyzed with the experimental and simulation results for different topologies. Copyright © 2014 John Wiley & Sons, Ltd.

Maximum power point tracking of single‐ended primary‐inductor converter employing a novel optimisation technique for proportional‐integral‐derivative controller

This study presents an optimisation technique for proportional-integral-derivative (PID) controller to achieve maximum-power-point tracking (MPPT) of single-ended primary-inductor converter (SEPIC). A new weight function is developed to optimise the PID parameters based on gradient-descent (GD) method by adding low-pass filter term. The proposed optimisation method does not stick in the local minima, which happens frequently with the traditional weight function used in GD method, where the low-pass filter term suppresses the noise and smooths the iteration process. The prototype of the proposed optimised PID-based SEPIC converter for photovoltaic inverter applications is built using DSP-based TMS320F28335. The performance of the proposed optimised PID-based MPPT scheme is tested in both simulation and experiment at different operating conditions. A performance comparison of the proposed GD method with the conventional GD PID is also made in real-time. It is found that the proposed optimised PID-based SEPIC converter is superior to the conventional GD PID controller in terms of power transfer and efficiency. Furthermore, the proposed optimised PID controller for two-level inverter can achieve a better total harmonic distortion (THD) level as compared to the multi-level inverter frequently used by researchers for the same purpose.