Top PDF Performance model for grid-connected photovoltaic inverters.

Performance model for grid-connected photovoltaic inverters.

Performance model for grid-connected photovoltaic inverters.

effectiveness of most inverters manufactured today is quite high, providing 98 to nearly 100% of the energy available from the PV array. Second, MPPT effectiveness is very difficult to measure because it requires simultaneous measurements of dc-power into the inverter and the maximum power point (P mp ) of the PV array. In most cases, the inverter is rapidly varying its operating voltage over a reasonably large range while “searching” for the array P mp . To complicate the situation, the only way to measure the array P mp accurately is to disconnect the inverter from the array and measure a current-voltage (I-V) curve, thus interrupting the MPPT process. Another procedure used to monitor an inverter’s MPPT characteristics involves using an accurate performance model for the PV array so that the measured dc-power into the inverter can be continuously compared to a predicted P mp for the PV array [2]. Using the array performance model to continuously predict P mp based on solar irradiance and array temperature measurements provides an effective way to observe the inverter’s MPPT characteristics, particularly during rapid variations in solar irradiance (clouds) where the MPPT algorithm must be versatile in order to “lock on” to a rapidly changing P mp . However, due to the uncertainty in the PV array
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Mathematical Model of a Photovoltaic Grid Connected Two Area Power System

Mathematical Model of a Photovoltaic Grid Connected Two Area Power System

In order to connect a PV array to a thermal power system, having the knowledge and applying the rules of power electronics would be of importance. [3 & 4] After obtaining the power output from the PV array, the first stage of this connection with the thermal power system is to use the boost converter. It increases the voltage to a suitable level, so that this voltage can be used as an input for the second stage of diagram which is the inverter. The inverter produces an AC current in order to be compatible with the AC nature of the power input applied to the grid and to be synchronized with its voltage and current. [3] The input to the PV system connected to the grid is the output of the PV array which is a DC current.
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Performance evaluation of small scale grid connected photovoltaic systems in Europe

Performance evaluation of small scale grid connected photovoltaic systems in Europe

significantly higher due to the climatic profile of the area. It is interesting to note however that the PR increase a two-axis tracker induces improves at higher latitudes due to the lower temperatures (Fig. 1) As latitude increases, the tracker improves energy production during summer further but at the same time the performance gains are reduced during winter, due to the high diffuse irradiation and sunshine hours distribution [27]. Table 4 displays the NPV of the PV system over a period of 20 years, as well as the equivalent value a bank deposit of the capital cost would yield (NPV b ) over the same
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Grid Connected Photovoltaic Systems with SmartGrid functionality

Grid Connected Photovoltaic Systems with SmartGrid functionality

The energy conversion efficiency, maximum power point tracking, anti-islanding, power quality and cost have been mentioned in Chapter 4 as the most important criteria to be considered when designing any power stage inverter. In chapter 5 the parameters for power stage inverters are estimated and proposed. The boost inductor and input capacitor which are important components to voltage source inverter (VSI) are calculated. Switching scheme and the L-C-L filter is proposed to give a clear sinusoidal output phase voltage of 230V from a DC capacitance bus estimated to handle 400V. The parameters are designed in Multism / NI LabView and the desired output simulation results are discussed in Chapter 6.
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Design and Implementation of Grid Connected Photovoltaic Systems

Design and Implementation of Grid Connected Photovoltaic Systems

Abstract: Renewable energy sources in solar form is the most imperative sustainable energy source as it is the endless source of energy. Photovoltaic system is a power system designed to supply usable solar power by means of photovoltaic’s. It consists of an several components, including solar panels to absorb and convert sunlight into electricity, a solar inverter to change the electric current from DC to AC. MPPT(Maximum Power Point Tracking) is a technique used commonly with wind turbines and photovoltaic solar systems to minimize power extraction under all conditions. A grid-connected photovoltaic power system, or grid-connected PV power system is an electricity generating solar PV power system that is connected to utility grid. A grid- connected PV system consists of solar panels, one or several inverters, a power conditioning unit and grid connected equipment. Power Quality refers to the ability of electrical equipment to consume the energy being supplied to it.
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System Performance Modelling of a Grid-Connected Photovoltaic System in UiTM, Malaysia

System Performance Modelling of a Grid-Connected Photovoltaic System in UiTM, Malaysia

The solar radiation and module temperature is the key factor in influencing the performance of grid connected PV system. In conclusion, this paper shows the mathematical approach to forecast the total output of PV systems based on two case studies that were selected; monocrystalline and polycrystalline for the residential system. Based on the results, the study was compared between actual and predicted electrical performance of grid connected photovoltaic systems. Furthermore, the predicted data and some output results were evaluated using MathCAD software. In future, this study will be evaluated in term of prediction of fault.
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Analysis and Mitigation of Temporary Over-Voltage (TOV) Phenomenon in Unintentionally Islanded Grid-Connected Photovoltaic (PV) Inverters

Analysis and Mitigation of Temporary Over-Voltage (TOV) Phenomenon in Unintentionally Islanded Grid-Connected Photovoltaic (PV) Inverters

In [59], a PV/battery unit is connected to the inverter through the dc-dc boost converters. Authors in [59] assumes that the PV/battery unit is in the islanded microgrids and uses a decentralized control strategies for the PV/battery unit. The PV/battery unit is controlled as voltage sources while a power curtailment control loop is used to modify the PV operating point to match the load autonomously whenever the PV power is higher than the load. This paper, however, does not provide any TOV analysis. In [60], a wind-photovoltaic-storage hybrid system is used for grid-connected and off-grid (islanded) operations. The PV unit is connected to the VSI through a dc-dc boost converter. Along with a grid-loss detection algorithm, authors in [60] propose a power management strategy for the hybrid system in order to ensure safe transition from grid-connected operation to off-grid (islanded) operation, but does not provide any analysis of the TOV during the transition period from grid-connected mode to islanded mode. The authors in [61] present new control strategies for a two-stage grid-connected PV system that allow the inverter to remain connected to the grid under faults. Reference [61], however, does not report any TOV analysis during an islanding scenario in the two-stage grid-connected PV system.
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Performance And Degradation Evaluation Of Grid-Connected Photovoltaic Systems At UTeM

Performance And Degradation Evaluation Of Grid-Connected Photovoltaic Systems At UTeM

DECLARATION I declare that this dissertation entitle “Performance and Degradation Evaluation of Grid-Connected Photovoltaic Systems at UTeM” is the result of my own research except as cited in the references. The dissertation has not been accepted for any degree and is not concurrently submitted in the candidature of any other degree.

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Design of Grid Connected Photovoltaic System

Design of Grid Connected Photovoltaic System

DOI: 10.4236/jpee.2017.58001 2 Journal of Power and Energy Engineering ing conditions [1] [2]. A boost converter is required to step up this low DC vol- tage to the required DC link voltage. The conventional boost converters cannot offer such a high voltage gain. Even in case of extreme duty ratio, the conversion efficiency is declined due to losses. This also increases the ratings of devices like output diode and other issues such as severe electromagnetic interference and reverse recovery [3]. The quadrature converters also offer a high voltage gain, but these have equal voltage stress across the switch [4] [5]. In particular cases, the line frequency transformer can also be used, but it increases the size and weight of photovoltaic system [6] [7]. The grid-connected photovoltaic systems also need the inverters for power conversion, grid interconnection and control optimization [8] [9]. Pulse width modulation (PWM) voltage source inverters are most commonly used in PV systems to invert DC voltage into AC before feeding to the grid or AC loads. The connection of inverters to the grid specifi- cally is dependent on the control scheme which is adopted by these inverters. Different control schemes have been under research for grid-connected inverters in the past decade [10] [11]. The phase locked loop technique is being the con- ventional. There are other PLL based grid synchronization techniques like power based PLL, quadrature PLL (QPLL). A PLL based new technique for synchroni- zation with the grid has also been developed in [12].
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Performance and Efficiency Simulation Study of a Smart Grid Connected Photovoltaic System

Performance and Efficiency Simulation Study of a Smart Grid Connected Photovoltaic System

The availability of non-renewable energy sources such as crude oil, natural gas, coal etc., is fast diminishing. So the renewable energy sources such as so- lar, hydropower, geothermal, wind, tidal energy, are gaining more and more importance. Many new developments to convert these renewable energy sources into usable forms are taking place. Most renewable energy sources are used to produce electricity. In this paper, a performance and efficiency simu- lation study of a smart-grid connected photovoltaic system using Chroma DC programmable power supply, AC programmable source and an Aurora In- verter is proposed. The simulation is performed in MATLAB environment where the Current-Voltage (I-V) and Power-Voltage (P-V) curves from the solar array simulator are generated and plotted. The proposed topology has been verified with satisfactory results. In addition, temperature and irradiance effects on I-V and P-V characteristic curves are verified. Also, the efficiency curves of the photovoltaic grid interface inverter are generated in the study. The MATLAB code developed in this paper is a valuable tool for design engi- neers comparing different inverters, calculating the optimum efficiency of a given inverter type.
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Mitigation of Harmonics in a Grid Connected Photovoltaic Inverter

Mitigation of Harmonics in a Grid Connected Photovoltaic Inverter

Abstract: Photovoltaic energy generation is one of the potential sources of renewable green energy because it is dirt free, unlimited source and requires less maintenance. Implementation of solar PV has been increasingly preferred for both commercial and residential purposes. The power quality issues are very common during the developing and integrating stages of solar PV. Inverters are considered as the main medium which enables the integration of solar PV into the grid. Due to the widespread use of inverters, harmonics are introduced into the system. These harmonics result in the degradation of power quality at the output. This research work is concerned with power quality when grid-connected systems are used. This paper proposes a new passive filter topology for a unipolar pulse width modulated single-phase inverter interfaced with the PV source and the grid. As a source for the system, a 25W photovoltaic panel is chosen. The panel is integrated with the proposed inverter and filter design. A hardware prototype was developed and suitable results were obtained and verified.
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Power quality and efficiency improvements for transformerless grid connected PV inverters

Power quality and efficiency improvements for transformerless grid connected PV inverters

The design of those control loops is greatly simplified if, from a control point of view, they do not interact. A number of authors such as Raoufi [16] and Varjasi [17] have either implicitly or explicitly assumed that the DC bus voltage control loop does not interact with the other loops and they invariably use a mathematical model based on capacitor power balance to design the DC bus voltage controller. An objective of this research is to consider the dynamic response of each control loop in detail. The DC bus voltage control loop operates outside the current control loop. The voltage controller provides the reference signal for the current controller. The current loop operates much faster than the outer voltage loop. So they can be designed independently. When designing the voltage loop, the current loop may be assumed to be a pure gain. The current loop, on the other hand is designed under the assumption that the controlled current does not influence the reference current. In this project, as is normal practice, the voltage control loop and current control loop will be independently designed. However experimental verification will be carried out to confirm that there is no interaction between them.
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Single-phase transformerless unipolar switched inverters for utility-connected photovoltaic applications

Single-phase transformerless unipolar switched inverters for utility-connected photovoltaic applications

In utility connected PV generation without batteries, the energy management system is much simpler because its function is to ensure that all the energy produced by the PV generator is instantaneously transferred to the grid supply. However, cloud movement influences the energy output from the PV panels and as such the voltage controller (responsible for managing the energy flow), has to respond to any intermittent loss in PV generation. The duration and magnitude of the intermittent loss in PV generation depends on the type of clouds and their speed of movement. It is assumed that variations with high rate of change are of low magnitudes. Jewell and Unruh have established that such variations, which may occur up to 15 times per minute, have magnitudes of the order of 5% of the installed PV generation capacity [13]. According to Jewell and Ramakumar [6], high magnitude variations (more than 50% loss of output) occur less frequently and have lower rates of change.
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Minimization in the dc component of  transformer less grid connected PV Inverters

Minimization in the dc component of transformer less grid connected PV Inverters

The grid connected photovoltaic system consist a line transformer between the (inverter) power converter and the grid. For the safety point of view the transformer gives galvanic isolation between the grid and PV system. It is ensures that no direct current component is injected into the grid. The low-frequency Transformers are bulky, heavy in weight and more costly and its power losses are brings down the overall system Efficiency. Now For removing the transformer and to achieve size, price and weight reduction and efficiency is also increasing of the system. So in this paper create an optimal grid connected PV system by removing the transformer from the system.
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Power quality and efficiency improvements for transformerless grid connected PV inverters

Power quality and efficiency improvements for transformerless grid connected PV inverters

Figure 1.1: Essential Components of a Grid-Connected Photovoltaic System 1 Figure 2.1: Output Voltage from Unipolar Switched Inverter 7 Figure 2.2: Output Voltage from Bipolar Switched Inverter 7 Figure 2.3: Typical Unfiltered Output Current of a Current Controlled Inverter 8 Figure 2.4: Current Controlled Grid Connected Full Bridge Inverter 9

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An Effective Solution to Minimize The Dc Component In Grid Connected Pv Inverters

An Effective Solution to Minimize The Dc Component In Grid Connected Pv Inverters

The main aim of project is dc component is a special issue in transformer less grid-connected photovoltaic (PV) inverter systems and may cause problems regarding system operation and safety. This paper has proposed an effective solution to minimize the dc component in three- phase ac currents and developed a software- based approach to mimic the blocking capacitors used for the dc component minimization, the so- called virtual capacitor.. A proportional integral- resonant controller is further designed to regulate the dc and line-frequency component in the current loop to provide precise control of the dc current. The proposed method has been validated on a 10-kVA experimental prototype, where the dc current has been effectively attenuated to be within 0.5% of the rated current. The total harmonic distortion and the second- order harmonic have also been reduced as well as the dc-link voltage ripple. Grid connected photovoltaic (PV) systems often include a line transformer between the power converter and the grid. The transformer guarantees galvanic isolation between the grid and the PV systems, thus fulfilling safety standards. Furthermore, it ensures that no direct current (dc) is injected to the grid . However, the low-frequency (50 or 60 Hz) transformer is bulky, heavy, and expensive
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Convex Optimization-Based Control Design for Parallel Grid-Connected Inverters

Convex Optimization-Based Control Design for Parallel Grid-Connected Inverters

Several active damping methods have been proposed in the literature for mitigating the effect of LCL output filter resonances, and a comprehensive review of the state-of-the- art is given in [6]. A common approach is to introduce active filter elements to the feedback loop and tune the parameters based on the model of a single-inverter infinite bus system. However, using a single-inverter model neglects all coupling dynamics in the grid and gives no guarantee for stability or performance in a system with multiple VSIs. Thus, approaches specifically aimed towards control design and stability analysis in grids with multiple VSIs have been proposed. For example, the tuning of current controllers for an arbitrary number of parallel inverters for PhotoVoltaic (PV) generation is presented in [7], [8] assuming identical VSIs. In [9], [10], [11] a state- space model of the complete system is constructed, and the resonance modes are classified based on modal participation factors. Another approach is breaking the system into intercon- nected component models that are easier to handle than the full system and then apply impedance-based transfer function models to tune filters in the frequency domain [5], [12]. In [13] a multivariable transfer function model for grids with multiple VSIs is developed, and it is shown that the model can be used for stability analysis through Nyquist diagrams. The modeling approach is further used in [14], [15] to derive design rules for proportional controllers based on root locus curves. A main issue of these methods is that the design is based on iterative procedures and does not scale well for more complex controller structures and larger systems. Furthermore, it is difficult to achieve explicit robustness and performance specifications, especially for uncertain systems.
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Limited Power Control of a Grid Connected Photovoltaic System

Limited Power Control of a Grid Connected Photovoltaic System

The objective of this thesis is to improve the performance of LPPT of photovoltaic plants. The previously reported LPPT methods, however, exhibit more oscillations at low power levels or require additional mode changing action. To avoid those difficulties, two novel LPPT control schemes are proposed. A dual stage photovoltaic system configuration with DC bus voltage being controlled by battery converter or DC-AC converter is considered. The control schemes proposed are called as VSLPPT control and VRLPPT control, respectively. Both the schemes are carefully designed with minimum deviation from the traditional MPPT control so as to ensure easy implementation. Unlike the existing FSLPPT control, the LPPT control techniques proposed exhibit fewer oscillations at low power levels with almost the same response time. The proposed VSLPPT control employs a variant form of the conventional MPPT algorithms with variable perturbation step size. The step size is adjusted in proportion to the absolute value of the difference between the reference power and the actual output power, but is capped at some upper limit. The upper limit applies to get satisfactory MPPT performance when the specified reference power level is higher than the maximum available power. The VSLPPT scheme performs better than the existing method at all power levels and is quite simple. The other LPPT control scheme proposed (called as VRLPPT) employs an additional continuous-time controller, but is based upon the uniform variable step size concept as is employed in the VSLPPT control. The performance of the VRLPPT control is far superior to the performance of the FSLPPT or VSLPPT control at low power levels. The actual superiority in performance happens because of conceptually employing infinitesimally small perturbation step sizes in the VRLPPT control. However, slightly more oscillations are observed near the maximum power point. The proposed LPPT control schemes are tested under different conditions, and their performances are thoroughly verified.
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Performance Evaluation of Grid-connected Solar Photovoltaic plant using PVSYST Software

Performance Evaluation of Grid-connected Solar Photovoltaic plant using PVSYST Software

Table 7 shows the balances and main results of Grid connected PV system. Yearly global horizontal irradiation is 1762.0 kWh/m 2 . The yearly global incident energy on the collector plane is 1855.5 kWh/m 2 . Energy available at the output of the PV array is 1449870 kWh. The energy injected into the grid is 1416980 kWh. The EffArrR is the efficiency of the PV array/rough area and the yearly average efficiency is 11.27 %. The yearly average efficiency of the system is 11.02 %. The average ambient temperature is 26.57 o C.

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SCADA system for remote control and monitoring of grid connected inverters

SCADA system for remote control and monitoring of grid connected inverters

C. Felipe et al. [14] introduce a wireless communication system related sensor concept that deals with temperature variations during the scaled industrial process. There is access to these sensors from anywhere since these sensors are used IoT tech- nology. The PLC executes according to the set points of temperature sensors, and this PLC can be contact or control via a graphical programming platform using which sensor data has been collected into a cloud. This system uses a SCADA to monitor the system. Also, the system communicates by forming of Petri nets which acts ac- cording to discrete events and the software used to model that communication system is WoPeD software.
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