Raseswari Pradhan

A Comparative Study on Maximum Power Point Tracking Techniques for Photovoltaic Power Systems

This paper provides a comprehensive review of the maximum power point tracking (MPPT) techniques applied to photovoltaic (PV) power system available until January, 2012. A good number of publications report on different MPPT techniques for a PV system together with implementation. But, confusion lies while selecting a MPPT as every technique has its own merits and demerits. Hence, a proper review of these techniques is essential. Unfortunately, very few attempts have been made in this regard, excepting two latest reviews on MPPT [Salas, 2006], [Esram and Chapman, 2007]. Since, MPPT is an essential part of a PV system, extensive research has been revealed in recent years in this field and many new techniques have been reported to the list since then. In this paper, a detailed description and then classification of the MPPT techniques have made based on features, such as number of control variables involved, types of control strategies employed, types of circuitry used suitably for PV system and practical/commercial applications. This paper is intended to serve as a convenient reference for future MPPT users in PV systems.

Characteristics evaluation and parameter extraction of a solar array based on experimental analysis

This paper proposes a Newton-Raphson based parameter extraction method based on experimental analysis for modeling of a PV panel. In this method, pre-knowledge of open-circuit voltage, short-circuit current, maximum power point voltage and current is not necessary. Hence, the proposed parameter extraction method and analysis described in this paper can be suitably employed to obtain the panel dynamics for a PV panel without any information of voltage, current or power rating. Together with the parameter extraction, I-V and P-V characteristics and maximum power point tracking analysis has also been conducted to the PV panel.

Double Integral Sliding Mode MPPT Control of a Photovoltaic System

This brief proposes a new maximum power point tracker (MPPT) for a stand-alone photovoltaic (PV) system using the concept of double integral sliding mode controller (DISMC). Performance of a sliding mode controller (SMC) is greatly influenced by the choice of the sliding surface. A double integral SMC uses double integral of tracking voltage error term in its sliding surface to eliminate steady-state error apart from providing robust control actions in face of system uncertainties. However, there is still difficulty of increased chattering and slow transient response in DISMC. In this brief, the objective is to exploit the merits of the DISMC for designing an MPPT for PV system whilst the disadvantages of chattering and slow transient response are alleviated by choosing a new sliding surface. The design of this new DISMC-MPPT system considers the uncertainties in weather conditions and variations in load. This MPPT has been implemented using a pulsewidth modulator controlled dc/dc converter to keep the switching frequency constant. Thus, designing the control and filter circuits becomes simpler. The effectiveness of the proposed DISMC has been validated using simulation and experimental results using a prototype PV control system setup.

A comparative study on solar array parameter extraction methods

This paper presents a comparative study on different solar array parameter extraction methods such as a modified Newton-Raphson-based technique proposed in this work and two other popular techniques such as Bouzidi’s Newton-Raphson method and Villalva’s iterative method. A single-diode-five-parameter model is considered in this study for modelling the solar (PV) panel. The parameters of interest such as series resistance, shunt resistance, diode ideality factor, dark saturation current and photo-generated current are extracted under standard test conditions (STC) using open circuit voltage, short circuit current and maximum power point voltage and current from manufacturer’s data-sheet. Comparative assessment of the above parameters extraction methods envisages that the modified Newton-Raphson extraction method provides accurate parameters with simple calculations.

A new digital double integral sliding mode maximum power point tracker for photovoltaic power generation application

This paper proposed a new digital double integral sliding mode controller based MPPT (DDISMC-MPPT) for tracking the maximum power point (MPP) of a photovoltaic (PV) panel. In this DDISMC-MPPT, a new double integral sliding surface has been chosen to enhance it operating with fixed switching frequency. The DDISMC-MPPT controller is designed considering the reaching and stability conditions. It is found that the proposed controller inherent robustness and is stable. Comparing with two available DDISMC-MPPTs such as Tans [6] and Jiaos [7] DDISMCs, this proposed DDISMC-MPPT performs better MPP tracking with less chattering. It is also confirmed that the settling time and chattering yielded in the proposed controller are less compared to that of Tans and Jiaos DDISMC-MPPTs.

A real-time linearized maximum power point tracker for photovoltaic system

This paper proposes a novel linearized maximum power point tracking (MPPT) method for a photovoltaic system. This method involves first the linearization of the photovoltaic (PV) module and the DC-DC converter. Hence, some of the difficulty level in switching control due to highly non-linear and time-variant characteristics of PV module is removed. Further, for an efficient maximum power point tracking (MPPT) performance of the PV system, the MPPT operation can be accomplished efficiently with a simple PI-controller. The proposed linearized MPPT method has been tested using one mono-crystalline (BP350) and other multi-crystalline (SSI-M6-205) solar panels. The solar panels have been tested at varying environmental conditions like solar radiations of 200 to 1000 watt/m2 and temperatures of -25 to 50°C considering various practical operating regions of the solar module. The effectiveness of the proposed linearized maximum power point tracking method has been validated by experimental results of Opal-RT.

Bacterial Foraging Optimization Approach to Parameter Extraction of a Photovoltaic Module

This paper presents a new parameter extraction method for photovoltaic (PV) modules exploiting Bacterial Foraging Optimization (BFO) technique. In a PV system, validation of the model of a PV module with correctly chosen parameters is essential. An efficient parameter extraction method is required to estimate the parameters of PV module. Although, a number of parameter extraction methods are available in literature but there is a need to explore parameter extraction methods that could extract globally optimized parameters in changing weather conditions. One of the recent evolutionary computing approaches called BFO exhibits global optimization performance. Therefore, we employ BFO for extraction of parameters of a PV module. The proposed BFO-based parameter extraction method has been tested for different types of PV modules at different test conditions. Analyzing both the simulation and experimental results obtained using BFO; it is found that the module parameters are more accurate compared to that of Newton–Raphson, particle swarm optimization, and enhanced simulated annealing methods.

An adaptive prediction error filter for photovoltaic power harvesting applications

This paper proposes a new adaptive prediction error filter (APEF) for harvesting maximum power from a photovoltaic (PV) system. The device used for maximum power harvesting application is known as maximum power point tracker (MPPT). Power harvesting efficiency is directly dependent on this MPPT; hence there is a necessity of a properly designed MPPT. An adaptive MPPT is capable of efficient operation for a wider operating range of the PV system such as solar irradiances and temperature. An adaptive MPPT usually required two components i.e.; a system identifier of the PV system and a controller. The proposed APEF-MPPT can perform both the role system identifier and controller. It also considers external disturbances at the designing stage, hence operates efficiently in the presence of disturbances. The APEF-MPPT consists of a linear predictor that tuned on-line with environmental conditions. The efficacy of the proposed APEFMPPT is investigated using a PV test system and found that it provides accurate and robust performance.

Design of A Grid Integrated PV System with MPPT Control and Voltage Oriented Controller using MATLAB/PLECES

This paper presents model of a grid-integrated photovoltaic array with Maximum Power Point Tracker (MPPT) and voltage oriented controller. The MPPT of the PV array is usually an essential part of PV system as MPPT helps the operating point of the solar array to align its maximum power point. In this model, the MPPT along with a DC-DC converter lets a PV generator to produce continuous power, despite of the measurement conditions. The neutral-point-clamped converter (NPC) with a boost converter raises the voltage from the panels to the DC-link. An LCL-filter smoothens the current ripple caused by the PWM modulation of the grid-side inverter. In addition to the MPPT, the system has two more two controllers, such as voltage controller and a current controller. The voltage control has a PI controller to regulate the PV voltage to optimal level by controlling the amount of current injected into the boost stage. Here, the grid-side converter transfers the power from the DC-link into the grid and maintains the DC-link voltage. Three-phase PV inverters are used for off-grid or designed to create utility frequency AC. The PV system can be connected in series or parallel to get the desired output power. To justify the working of this model, the grid-integrated PV system has been designed in MATLAB/PLECS. The simulation shows the P-V curve of implemented PV Array consisting 4 X 20 modules, reactive, real power, grid voltage and current.

Design of sliding mode controller for three phase grid connected photovoltaic system

This paper proposes a sliding mode control methodology for three phase grid connected photovoltaic (PV) generator. It consists of a PV array, a voltage source inverter which is connected to the grid through a grid filter. A fractional open circuit voltage maximum power point tracking (FOCV-MPPT) algorithm is used to extract the maximum power from the PV system. The current reference is generated directly from the PV array power information and the current controller uses sliding mode controller for the tight control of inverter current that is fed to the grid. The complete system is simulated and results are analyzed to validate the proposed methodology for grid connected PV generation system.