Browsing by Author "Ramana, V.V."

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A Novel AC Current Sensorless Hysteresis Control for Grid-Tie Inverters
(Institute of Electrical and Electronics Engineers Inc., 2020) Damodaran, R.; Mudlapur, A.; Ramana, V.V.; Balasubramanian, B.; Mishra, S.
Amongst the modulation techniques used for grid-Tie inverters (GTIs), hysteresis current control (HCC) facilitates simple, stable and rugged control with improved dynamic response. However the variable switching frequency of HCC demands high precision AC current sensors (CS) which introduce noise in the power circuit in addition to measurement noise and delay. Therefore, this brief presents a hysteresis current control without AC current sensor based on switching instant computation for a two-level GTI. The proposed control strategy uses the DC link and instantaneous grid voltages to calculate the switching instants. The conventional methods of calculating switching instant of HCC can result in tracking errors. Hence the computations are modified in the proposed algorithm considering the effects of non-linearity in error current and dynamic variations due to supply and load changes. A single-phase GTI is simulated with the proposed control and the results are verified experimentally. The proposed method is observed to considerably reduce the computational time, DC shift and total harmonic distortion compared to the commonly used sensorless current control. © 2004-2012 IEEE.
An accurate modeling of different types of photovoltaic modules using experimental data
(International Journal of Renewable Energy Research, 2016) Ramana, V.V.; Jena, D.; Gaonkar, D.N.
In this paper an approach to model different types of PV modules using single diode model is presented. The proposed method utilizes the characteristics of diode ideality factor, shunt resistance and series resistance independently for developing accurate solar PV model. Apart from this, the proposed model utilizes experimental values obtained from the solar array simulator for implementing the proposed approach. The procedure mainly focuses on developing an accurate method for thin film solar modules using a simplified approach. The model is implemented in MATLAB and is validated with existing model and experimental values obtained from solar array simulator.
An accurate modeling of photovoltaic system for uniform and non-uniform irradiance
(International Journal of Renewable Energy Research ijrereditor@gmail.com, 2015) Ramana, V.V.; Jena, D.
Efficient modeling and simulation of photovoltaic (PV) systems has become more important due to the wide integration of solar energy in modern power systems. The equations describing the PV systems are transcendental nonlinear in nature, this results a slow and inefficient simulations for long-term analysis. This paper proposes a modified approach of modeling photovoltaic array for uniform and non-uniform irradiance condition. Initially for uniform irradiance condition single diode model is used as equivalent circuit. A method based on adaptively varying the value of series resistance is proposed to find the equivalent circuit parameters. The proposed model is simulated using MATLAB and results are validated using the experimental results obtained from the datasheet values and other models in the literature. The model is extended for non-uniform irradiance and the results are validated. The proposed methodology found to have advantage over the other conventional methods in terms of accuracy and less simulation time.
An Iterative Analytical Solution for Calculating Maximum Power Point in Photovoltaic Systems under Partial Shading Conditions
(Institute of Electrical and Electronics Engineers Inc., 2019) Mudlapur, M.; Ramana, V.V.; Damodaran, R.; Balasubramanian, B.
Detection of maximum power point (MPP) is one of the most sought-after topics in the field of photovoltaic systems. There are many approaches to detecting MPP, amongst these are analytical methods. Analytical methods use mathematical functions to solve the given problem and therefore are one of the dominant strategies. However, their applications to detect MPP have been limited to study only uniform shading conditions. The use of analytical methods to detect MPP for more challenging cases like partial shading conditions is yet to be investigated. In this brief, an analytical solution to identify MPP under partial shading conditions is proposed. Equations describing photovoltaic panels and MPP conditions are derived by applying fundamental circuit laws. The derived equations are non-linear and can be solved using numerical techniques available in most of the simulation packages. The proposed model can theoretically detect the MPP amongst 'N' peaks. The results from the simulation are verified by conducting experimentation with standard algorithms available in the literature. The results from simulation and experimentation are found to agree with each other. © 2004-2012 IEEE.
Collaborative Filtering for Book Recommendation System
(2020) Ramakrishnan, G.; Saicharan, V.; Chandrasekaran, K.; Rathnamma, M.V.; Ramana, V.V.
Collaborative filtering is one of the most important techniques in the market nowadays. It is prevalent in almost every aspect of the internet, in e-commerce, music, books, social media, advertising, etc., as it greatly grasps the needs of the user and provides a comfortable platform for the user to find what they like without searching. This method has a few drawbacks; one of them being, it is based only on the explicit feedback given by the user in the form of a rating. The real needs of a user are also demonstrated by various implicit indicators such as views, read later lists, etc. This paper proposes and compares various techniques to include implicit feedback into the recommendation system. The paper attempts to assign explicit ratings to users depending on the implicit feedback given by users to specific books using various algorithms and thus, increasing the number of entries available in the table. � 2020, Springer Nature Singapore Pte Ltd.
Collaborative Filtering for Book Recommendation System
(Springer, 2020) Ramakrishnan, G.; Saicharan, V.; Chandrasekaran, K.; Rathnamma, M.V.; Ramana, V.V.
Collaborative filtering is one of the most important techniques in the market nowadays. It is prevalent in almost every aspect of the internet, in e-commerce, music, books, social media, advertising, etc., as it greatly grasps the needs of the user and provides a comfortable platform for the user to find what they like without searching. This method has a few drawbacks; one of them being, it is based only on the explicit feedback given by the user in the form of a rating. The real needs of a user are also demonstrated by various implicit indicators such as views, read later lists, etc. This paper proposes and compares various techniques to include implicit feedback into the recommendation system. The paper attempts to assign explicit ratings to users depending on the implicit feedback given by users to specific books using various algorithms and thus, increasing the number of entries available in the table. Â© 2020, Springer Nature Singapore Pte Ltd.
Effect of Partial Shading on PV Fed Induction Motor Water Pumping Systems
(Institute of Electrical and Electronics Engineers Inc., 2019) Mudlapur, M.; Ramana, V.V.; Damodaran, R.; Balasubramanian, B.; Mishra, S.
Partial shading is one of the certain conditions in photovoltaic (PV) power plants. Often the panels get partially shaded due to soiling, clouds, and trees. The effect of shading is of high concern and importance especially in applications such as water pumps due to agricultural environments in which they are employed in. However, the research focus on PV fed pumps till date has been restricted to only uniform shading conditions. Unlike uniform shading conditions during maximum power tracking, where the panel voltage remains almost constant for an entire range of irradiance, partial shading offer conditions such as highly variable panel voltage and transitions of intermediate DC-DC power converter from continuous conduction mode to discontinuous conduction mode. These effects severely affect the performance of the power converter and, therefore, the power output of the pump. This paper presents a study on the effects caused by partial shading conditions on pumps through simulations and verified by experimentations. The simulation and experimental results are found to be in good agreement with each other. This research thus helps in understanding the detrimental effects caused by partial shading conditions and thus serves as a reference tool for practitioners who wish to study PV fed pumps. © 1986-2012 IEEE.
Efficient global peak tracking of PV system under mismatching conditions using searching technique and bisection method
(2018) Ramana, V.V.; Mudlapur, A.; Damodaran, R.V.; Venkatesaperumal, B.; Mishra, S.
Rapidly increasing energy demand is leading to increase in installation of photovoltaic (PV) plants across the globe. The PV modules are subjected to various conditions like shading, soiling and degradation because of which the performance of PV panels deteriorates. This will affect the characteristics of PV module which may lead to several stairs in I-V curves and several peaks in P-V curve. In this paper the various causes of occurrences of mismatching conditions are analyzed. An efficient two stage algorithm that tracks global maximum power point (GMPP) accurately under such mismatching conditions is proposed in the paper. In the first stage, a simple searching technique and bisection method are used to bring the operating point to the proximity of global maximum. In the second stage, hill climbing method maintains the operating point at global peak. MATLAB Simulations and experimental verifications are performed for validating the proposed approach. � 2018 IEEE.
Efficient global peak tracking of PV system under mismatching conditions using searching technique and bisection method
(Institute of Electrical and Electronics Engineers Inc., 2018) Ramana, V.V.; Mudlapur, A.; Damodaran, R.; Balasubramanian, B.; Mishra, S.
Rapidly increasing energy demand is leading to increase in installation of photovoltaic (PV) plants across the globe. The PV modules are subjected to various conditions like shading, soiling and degradation because of which the performance of PV panels deteriorates. This will affect the characteristics of PV module which may lead to several stairs in I-V curves and several peaks in P-V curve. In this paper the various causes of occurrences of mismatching conditions are analyzed. An efficient two stage algorithm that tracks global maximum power point (GMPP) accurately under such mismatching conditions is proposed in the paper. In the first stage, a simple searching technique and bisection method are used to bring the operating point to the proximity of global maximum. In the second stage, hill climbing method maintains the operating point at global peak. MATLAB Simulations and experimental verifications are performed for validating the proposed approach. Â© 2018 IEEE.
Global Peak Tracking of Photovoltaic Array under Mismatching Conditions Using Current Control
(Institute of Electrical and Electronics Engineers Inc., 2019) Ramana, V.V.; Mudlapur, M.; Damodaran, R.; Balasubramanian, B.; Mishra, S.
Characteristics of photovoltaic arrays exhibit multiple peaks under mismatching conditions. In order to harness maximum energy, it is imperative to track the global maximum power point. A novel global peak tracking algorithm is proposed using current control in this paper. The proposed method operates in the backward phase and forward phase to track the global peak. The objective of the proposed algorithm is to track the global maximum accurately with minimum tracking time. The enhanced performance of the proposed algorithm is verified using simulations by comparing it with an existing method. Experimental validation is done using a solar array simulator, boost converter, resistive load, and dSPACE controller. Experimental results are in close agreement with simulation. The proposed algorithm is intended to track the global peak of a PV string that contains a group of modules. © 1986-2012 IEEE.
Maximum power point tracking of PV array under non-uniform irradiance using artificial neural network
(2015) Ramana, V.V.; Jena, D.
This paper presents a maximum power point tracking (MPPT) method for tracking the global peak (GP) of photovoltaic (PV) array under non-uniform irradiance using artificial neural network (ANN). A feed forward multilayer perceptron model with Levenberg - Marquardt back propagation algorithm is used for tracking the global peak. The MPPT algorithm takes irradiance of PV modules as input and gives duty ratio of boost converter as output. The MPPT presented using ANN is compared with conventional hill climbing (HC) method and the actual values obtained from the P-V characteristics. Root Mean Square Error (RMSE) of PV array output power is calculated for both hill climbing method and proposed ANN method. Finally, a qualitative comparison is made between hill climbing method and ANN method. � 2015 IEEE.
Maximum power point tracking of PV array under non-uniform irradiance using artificial neural network
(Institute of Electrical and Electronics Engineers Inc., 2015) Ramana, V.V.; Jena, D.
This paper presents a maximum power point tracking (MPPT) method for tracking the global peak (GP) of photovoltaic (PV) array under non-uniform irradiance using artificial neural network (ANN). A feed forward multilayer perceptron model with Levenberg - Marquardt back propagation algorithm is used for tracking the global peak. The MPPT algorithm takes irradiance of PV modules as input and gives duty ratio of boost converter as output. The MPPT presented using ANN is compared with conventional hill climbing (HC) method and the actual values obtained from the P-V characteristics. Root Mean Square Error (RMSE) of PV array output power is calculated for both hill climbing method and proposed ANN method. Finally, a qualitative comparison is made between hill climbing method and ANN method. Â© 2015 IEEE.
Modeling of photovoltaic system for uniform and non-uniform irradiance: A critical review
(Elsevier Ltd, 2015) Jena, D.; Ramana, V.V.
A critical review on various modeling approaches of photovoltaic array both under uniform and non-uniform irradiance is presented in this paper. The main approaches that have been deliberated are based on the variation of analytical methods, classical optimization techniques and soft computing techniques. The review has been taken from papers published up to 2015. In this paper a detailed description and classifications of modeling techniques for both uniform and non-uniform irradiance conditions are presented. Modeling of PV systems under uniform irradiance is classified into non-iterative methods, iterative methods, artificial intelligence based methods and dynamic models. Under non-uniform irradiance, they are classified into non-iterative methods, iterative methods and artificial intelligence based methods. It is envisaged that this paper can serve as valuable information for researchers to work on photovoltaic array modeling under partial shaded condition. © 2015 Elsevier Ltd. All rights reserved.
Modified Hysteresis Current Control for Single Phase Solar Grid-tie Z-Source Inverter
(2018) Viswadev, R.; Venkatesaperumal, B.; Mudlapur, A.; Ramana, V.V.; Mishra, S.
This paper proposes a simple novel technique to determine the shoot-through states in a hysteresis controlled solar grid connected single phase Z-source inverter (ZSI). The ZSI along with the proposed controller exhibits high efficiency due to the single stage conversion. Fast and robust dynamic response can be obtained by using hysteresis control. Hence the proposed control for ZSI is ideal for grid integration of photovoltaic sources. The error current is used to determine shoot-through states based on calculation of current limits as a function of the boost ratio and modulation index. The maximum boost ratio, that can be obtained by the proposed control without causing low frequency ripples in Z-source network, is expressed as a function of modulation index. To verify the analysis, simulations are performed for input and grid voltage variations using MATLAB-Simulink platform. � 2018 IEEE.
Modified Hysteresis Current Control for Single Phase Solar Grid-tie Z-Source Inverter
(Institute of Electrical and Electronics Engineers Inc., 2018) Damodaran, R.; Balasubramanian, B.; Mudlapur, A.; Ramana, V.V.; Mishra, S.
This paper proposes a simple novel technique to determine the shoot-through states in a hysteresis controlled solar grid connected single phase Z-source inverter (ZSI). The ZSI along with the proposed controller exhibits high efficiency due to the single stage conversion. Fast and robust dynamic response can be obtained by using hysteresis control. Hence the proposed control for ZSI is ideal for grid integration of photovoltaic sources. The error current is used to determine shoot-through states based on calculation of current limits as a function of the boost ratio and modulation index. The maximum boost ratio, that can be obtained by the proposed control without causing low frequency ripples in Z-source network, is expressed as a function of modulation index. To verify the analysis, simulations are performed for input and grid voltage variations using MATLAB-Simulink platform. Â© 2018 IEEE.
On Feature Models of Home Automation Systems towards Smart Sensing
(Institute of Electrical and Electronics Engineers Inc., 2020) Patil, P.; Aparna, R.; Chandrasekaran, K.; Rathnamma, M.V.; Ramana, V.V.
The growing need for innovation in software products and an increase in their complexity has demanded an evolution in the software industry in recent years. Domain Analysis assists software developers in understanding the domains leading to significant improvement in their software development. Domain Analysis can be easily carried out using Feature Modelling by identifying the commonalities and variations among attributes of the domain. On the other hand, Home Automation is a developing domain and is now seeing an increase in the number and complexity of products. The heterogeneity of the home automation system elements introduced a lot of complexity to the developers. The commonly observable features and variations arising from HA systems allow us to visualize Home Automation (HA) systems as a Software Product Line (SPL). In this paper, we aim to adopt the Feature Modelling technique for Domain Analysis of the HA system. The efficacy and validity of this approach is evaluated with the help of proof of concepts. Â© 2020 IEEE.
Real and reactive power control of solar grid-tie inverter under distorted grid conditions
(2018) Viswadev, R.; Ramana, V.V.; Venkatesaperumal, B.; Mishra, S.
Due to increasing density of integration of distributed generation systems (DGS) to the utility grid, continuous power supply from DGS is being considered desirable during temporary grid faults, to provide support to the grid under conditions like voltage sags. Researchers have been focusing on improved topologies and control strategies in order to enhance the performance of solar grid-tied inverters, especially during grid faults. This paper presents a simple yet accurate control strategy for three-level four-wire grid-tie inverters for real and reactive power injection which operates satisfactorily under distorted grid conditions. Independent control of the input and output side is obtained by using two-stages, with boost converter obtaining maximum power from the solar panels, and inverter injecting this power into the grid with grid standards being met. A DC link balancing technique using proportional controller is also presented. A three-level neutral point clamped grid-tie inverter with the proposed control is modeled in MATLAB-Simulink platform and its effectiveness, in terms of accuracy of operation under non-ideal grid conditions and reduction in total harmonic distortion, is validated using the simulation results. � 2018 IEEE.
Real and reactive power control of solar grid-tie inverter under distorted grid conditions
(Institute of Electrical and Electronics Engineers Inc., 2018) Damodaran, R.; Ramana, V.V.; Balasubramanian, B.; Mishra, S.
Due to increasing density of integration of distributed generation systems (DGS) to the utility grid, continuous power supply from DGS is being considered desirable during temporary grid faults, to provide support to the grid under conditions like voltage sags. Researchers have been focusing on improved topologies and control strategies in order to enhance the performance of solar grid-tied inverters, especially during grid faults. This paper presents a simple yet accurate control strategy for three-level four-wire grid-tie inverters for real and reactive power injection which operates satisfactorily under distorted grid conditions. Independent control of the input and output side is obtained by using two-stages, with boost converter obtaining maximum power from the solar panels, and inverter injecting this power into the grid with grid standards being met. A DC link balancing technique using proportional controller is also presented. A three-level neutral point clamped grid-tie inverter with the proposed control is modeled in MATLAB-Simulink platform and its effectiveness, in terms of accuracy of operation under non-ideal grid conditions and reduction in total harmonic distortion, is validated using the simulation results. Â© 2018 IEEE.
Review of techniques for automatic text summarization
(Springer, 2020) Prakash, B.S.; Sanjeev, K.V.; Prakash, R.; Chandrasekaran, K.; Rathnamma, M.V.; Ramana, V.V.
Summarization refers to the process of reducing the textual components such as words and sentences but conveying most of the information in the input text. Research in summarization is very prominent in the current scenario where the textual data available is enormous and contains valuable information. People have been interested in summarization since time immemorial. The methods adopted in the past relied on manually reading the text and based on oneâ€™s understanding of the text, manually generating the summary. In the current world, due to the explosion of data from Internet and social media, the manual process is very tedious and time-consuming. As a result, there is a great need to automate the process of summarization. In this paper, we summarize most of the researches in the field of summarization which is unique and path-breaking. Â© Springer Nature Singapore Pte Ltd. 2020.
Simple and accurate method of modeling Photovoltaic module: A different approach
(2013) Jena, D.; Ramana, V.V.
This paper proposes a different method of modeling Photovoltaic (PV) System in uniform irradiance conditions. It provides a simple and accurate method of modeling PV system using a single diode model by considering series and shunt resistance. This model computes five parameters and is having better accuracy than the existing models in literature. The accuracy of the proposed modeling technique is validated by comparing the model with the experimental values and datasheet values. The proposed model can be extended for modeling the effect of non-uniform irradiance conditions on PV system and also to track the maximum power from the PV source under non-uniform irradiance conditions. � 2013 IEEE.