A Simple, Efficient, and Novel Standalone Photovoltaic Inverter Configuration With Reduced Harmonic Distortion
TL;DR: A novel photovoltaic inverter topology is put forward, which incorporates a new maximum power point tracking (MPPT) scheme based on shading pattern identification using the artificial neural network, single-input and multi-output (SIMO) converter, and multilevel inverter (MLI).
Abstract: This paper is put forward a novel photovoltaic (PV) inverter topology for maximum solar power utilization, which incorporates a new maximum power point tracking (MPPT) scheme based on shading pattern identification using the artificial neural network, single-input and multi-output (SIMO) converter, and multilevel inverter (MLI). The performance of the proposed MPPT scheme is benchmarked under partially shaded conditions. In continuation, the PV voltage is fed to the SIMO converter, where the converter produces four independent (V1, V2, V3 and V4) voltages with different magnitudes. The MLI converts the dc output voltage of the SIMO converter into ac to feed the utility, with reduced harmonic distortion. This MLI consists of eight switching devices and produces thirty one level ac output voltage with very less harmonic distortion. The salient feature associated with the proposed topology is that the proposed MPPT scheme extracts utmost power in any weather conditions and MLI feeds the utility. An experimental prototype is designed and developed to verify the performance of the proposed PV inverter topology. FPGA Spartan trainer kit is used to program pulses required for the MLI and converter of the proposed topology.
Citations
More filters
TL;DR: Although the recent integration requirements can improve the grid operation, stability, security, and reliability, further improvements are still required with respect to protective regulations, global harmonization, and control optimization.
206 citations
TL;DR: The obtained results show that the proposed controller fulfilled the recent standard requirements in mitigating power quality (PQ) events, and can increase the effort towards the development of smooth PVPP integration by optimizing the design, operation and control strategies towards high PQ and green electricity.
Abstract: The generation and integration of photovoltaic power plants (PVPPs) into the utility grid have increased dramatically over the past two decades. In this sense, and to ensure a high quality of the PVPPs generated power as well as a contribution on the power system security and stability, some of the new power quality requirements imposed by different grid codes and standards in order to regulate the installation of PVPPs and ensure the grid stability. This study aims to investigate the recent integration requirements including voltage sag, voltage flicker, harmonics, voltage unbalance, and frequency variation. Additionally, compliance controls and methods to fulfill these requirements are developed. In line with this, a large-scale three-phase grid-connected PVPP is designed. A modified inverter controller without the use of any extra device is designed to mitigate the sage incidence and achieve the low-voltage ride-through requirement. It can efficiently operate at normal conditions and once sag or faults are detected, it can change the mode of operation and inject a reactive current based on the sag depth. A dynamic voltage regulator and its controller are also designed to control the voltage flicker, fluctuation, and unbalance at the point of common coupling between the PVPP and the grid. The voltage and current harmonics are reduced below the specified limits using proper design and a RLC filter. The obtained results show that the proposed controller fulfilled the recent standard requirements in mitigating power quality (PQ) events. Thus, this study can increase the effort towards the development of smooth PVPP integration by optimizing the design, operation and control strategies towards high PQ and green electricity.
66 citations
TL;DR: In this article, a novel asymmetric 21-level multilevel inverter topology for solar PV application is presented, where the PV voltage is boosted over the DC link voltage using a three-level DC-DC boost converter interfaced in between the solar panels and the inverter.
Abstract: This article presents a novel asymmetrical 21-level multilevel inverter topology for solar PV application. The proposed topology achieves 21-level output voltage without H-bridge using asymmetric DC sources. This reduces the devices, cost and size. The PV standalone system needs a constant DC voltage magnitude from the solar panels, maximum power point tracking (MPPT) technique used for getting a stable output by using perturb and observe (P&O) algorithm. The PV voltage is boosted over the DC link voltage using a three-level DC-DC boost converter interfaced in between the solar panels and the inverter. The inverter is tested experimentally with various combinational loads and under dynamic load variations with sudden load disturbances. Total standing voltage with a cost function for the proposed MLI is calculated and compared with multiple topologies published recently and found to be cost-effective. A detailed comparison is made in terms of switches count, and sources count, gate driver boards, the number of diodes and capacitor count and component count level factor with the same and other levels of multilevel inverter and found to be the proposed topology is helpful in terms of its less TSV value, devices count, efficient and cost-effective. In both simulation and experimental results, total harmonic distortion (THD) is observed to be the same and is lower than 5% which is under IEEE standards. A hardware prototype is implemented in the laboratory and verified experimentally under dynamic load variations, whereas the simulations are done in MATLAB/Simulink.
32 citations
TL;DR: In this article, a novel micro multilevel inverter based stand-alone solar photovoltaic system is presented, which is a micro inverter having multi-level inverter structure.
27 citations
TL;DR: An improved harmonics mitigation scheme for a Multilevel DC-Link Inverter (MLDCLI), which is a variant of MMC, is proposed, a modified version of the conventional Nearest Level Modulation (NLM) scheme, termed as modified Nearest level Modulations (mNLM).
Abstract: Modular Multilevel Converters (MMC) are gaining importance because of their flexible structure, re-configurable property, and simplicity of operation. The operation of MMC at a low-switching frequency (LSF) helps in enhancing the performance of the converter. This paper proposes an improved harmonics mitigation scheme for a Multilevel DC-Link Inverter (MLDCLI), which is a variant of MMC. The proposed scheme is a modified version of the conventional Nearest Level Modulation (NLM) scheme, termed as modified Nearest Level Modulation (mNLM) Scheme. The proposed scheme is effective compared to NLM because of the choice of the switching angles obtained by the use of the algorithm proposed. The MLDCLI topology is operated for twelve different configurations, and mNLM is implemented on all the configurations. Using MATLAB software, the simulation results are validated, and the same is extended to a hardware prototype. The simulation and experimental results of NLM and mNLM schemes are compared. The effectiveness of the proposed scheme is evident by the reduced voltage THD, increased rms voltage, increased rms current, and increased output power.
25 citations
References
More filters
TL;DR: A modified variable step size INC MPPT algorithm is proposed, which automatically adjusts the step size to track the PV array maximum power point and can effectively improve the MPPT speed and accuracy simultaneously.
Abstract: Maximum power point tracking (MPPT) techniques are employed in photovoltaic (PV) systems to make full utilization of PV array output power which depends on solar irradiation and ambient temperature. Among all the MPPT strategies, the incremental conductance (INC) algorithm is widely used due to the high tracking accuracy at steady state and good adaptability to the rapidly changing atmospheric conditions. In this paper, a modified variable step size INC MPPT algorithm is proposed, which automatically adjusts the step size to track the PV array maximum power point. Compared with the conventional fixed step size method, the proposed approach can effectively improve the MPPT speed and accuracy simultaneously. Furthermore, it is simple and can be easily implemented in digital signal processors. A theoretical analysis and the design principle of the proposed method are provided and its feasibility is also verified by simulation and experimental results.
1,235 citations
"A Simple, Efficient, and Novel Stan..." refers methods in this paper
...In order to extract maximum solar power, Maximum Power Point (MPP) of the PV system has to be tracked continuously using a Maximum Power Point Tracking (MPPT) controller [1]....
[...]
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
"A Simple, Efficient, and Novel Stan..." refers background in this paper
...time, simple to implement and moreover economical [21]....
[...]
TL;DR: In this article, a detailed theoretical and experimental comparison of the two perturb and observe (P&O) implementation techniques on the basis of system stability, performance characteristics, and energy utilization for standalone PV pumping systems is presented.
Abstract: The energy utilization efficiency of commercial photovoltaic (PV) pumping systems can be significantly improved by employing simple perturb and observe (P&O) maximum power point tracking algorithms. Two such P&O implementation techniques, reference voltage perturbation and direct duty ratio perturbation, are commonly utilized in the literature but no clear criteria for the suitable choice of method or algorithm parameters have been presented. This paper presents a detailed theoretical and experimental comparison of the two P&O implementation techniques on the basis of system stability, performance characteristics, and energy utilization for standalone PV pumping systems. The influence of algorithm parameters on system behavior is investigated and the various advantages and drawbacks of each technique are identified for different weather conditions. Practical results obtained using a 1080-Wp PV array connected to a 1-kW permanent magnet dc motor-centrifugal pump set show very good agreement with the theoretical analysis and numerical simulations.
646 citations
"A Simple, Efficient, and Novel Stan..." refers methods in this paper
...In [4], presented the two Perturb and Observe (P&O) implementation technique based on the parameters like voltage and duty ratio and both the algorithm are applied to the solar pumping system....
[...]
TL;DR: A novel variable step-size incremental-resistance MPPT algorithm is introduced, which not only has the merits of INC but also automatically adjusts the step size to track the PV array MPP.
Abstract: Maximum power point (MPP) tracking (MPPT) techniques are widely applied in photovoltaic (PV) systems to make PV array generate peak power which depends on solar irradiation. Among all the MPPT strategies, the incremental-conductance (INC) algorithm is widely employed due to easy implementation and high tracking accuracy. In this paper, a novel variable step-size incremental-resistance MPPT algorithm is introduced, which not only has the merits of INC but also automatically adjusts the step size to track the PV array MPP. Compared with the variable step-size INC method, the proposed scheme can greatly improve the MPPT response speed and accuracy at steady state simultaneously. Moreover, it is more suitable for practical operating conditions due to a wider operating range. This paper provides the theoretical analysis and the design principle of the proposed MPPT strategy. Simulation and experimental results verify its feasibility.
599 citations
"A Simple, Efficient, and Novel Stan..." refers background in this paper
...In recent times, miniature range installation of solar power generating units on building rooftops is trending and also offers as an alternative primary source of energy for household purposes during emergence [2], [3]....
[...]
TL;DR: Simulation and experimental results showed that the proposed algorithm accurately tracks the maximum power and avoids the drift in fast changing weather conditions.
Abstract: The perturb and observe (P&O) maximum power point tracking (MPPT) algorithm is a simple and efficient tracking technique. However, the P&O tracking method suffers from drift in case of an increase in insolation $(G) $ , and this drift effect is severe in case of a rapid increase in insolation. Drift occurs due to the incorrect decision taken by the conventional P&O algorithm at the first step change in duty cycle during increase in insolation. A modified P&O technique is proposed to avoid the drift problem by incorporating the information of change in current $(\Delta I) $ in the decision process in addition to change in power $(\Delta P)$ and change in voltage $(\Delta V) $ . The drift phenomena and its effects are clearly demonstrated in this paper for conventional P&O algorithm with both fixed and adaptive step size technique. A single-ended primary inductance converter is considered to validate the proposed drift-free P&O MPPT using direct duty ratio control technique. MATLAB/Simulink is used for simulation studies, and for experimental validation, a microcontroller is used as a digital platform to implement the proposed algorithm. The simulation and experimental results showed that the proposed algorithm accurately tracks the maximum power and avoids the drift in fast changing weather conditions.
420 citations
"A Simple, Efficient, and Novel Stan..." refers background in this paper
...During the change in irradiance there exists drift in the power curve, in order to eliminate the drift a new resolution is introduced into the system based on the panel current [7]....
[...]