Abu Tariq

Development of an Analog Maximum Power Point Tracker for Photovoltaic Panel

Maximum power point trackers (MPPT) are used to operate a solar photovoltaic (PV) panel at its maximum power point (MPP). A number of tracking algorithms have been used in the past. A simple and cheap analog MPPT has been simulated and constructed. The MPP tracking algorithm is based on the fact that the MPP voltage is approximately a fixed percentage of the open circuit voltage of the PV panel. The PV panel is usually disconnected from the load after regular intervals, to record the open circuit voltage. In the present work, an unloaded pilot PV panel, with characteristics similar to those of the main PV panel and installed under similar conditions, is used to measure the open circuit voltage. The main PV panel is never disconnected from the load, resulting in increased energy output. The simulation and experimental results show that the panel tracks the MPP under changing atmospheric and load conditions

Simulation and study of a grid connected multilevel converter (MLC) with varying DC input

Multilevel line commutated inverters for renewable energy systems have gained popularity in recent times, especially in the distributed generation where a number of batteries, fuel cells, solar cell, and micro-turbines can be connected through a MLC to feed the grid. They can synthesize higher output voltage levels and can generate near sinusoidal voltages. This paper presents analysis of a grid connected MLC as an inverter having variable dc sources(which can be the output of wind farms, solar panels etc.). A Computer simulation analysis using SIMULINK/ MATLAB has been done to minimize total harmonic distortion (THD) by increasing the stages and by varying the delay angles for varying dc input to the multilevel inverter. A comparative study of different stages of MLC for different value of dc input has also been studied. The results has been tabulated and discussed.

Development of microcontroller-based maximum power point tracker for a photovoltaic panel

Maximum power point trackers (MPPT) are used to operate a solar photovoltaic (PV) panel at its maximum power point (MPP). In this paper a microcontroller based MPPT is realized. Two tracking algorithms, namely, perturb and observation (PAO) algorithm and maximum power point voltage (MPPV) algorithm have been implemented. The MPPT is tested under varying insolation and load conditions. It has been shown that with PAO algorithm, the controller takes significant time to track the MPP. Moreover, the operating point oscillates around the MPP. The large tracking time and oscillations around the MPP result in significant energy loss during the tracking process. The wastage of power is more significant in rapidly changing atmospheric condition, as the controller has to search for new operating point more frequently. On the other hand, with the MPPV algorithm, the MPP is tracked very quickly with no oscillations around the MPP

Theoretical and experimental analysis of photovoltaic water pumping system

There is a theoretical and experimental analysis of a motor-pump system directly coupled to a PV array. The motor-pump system consists of a permanent magnet de (PMDC) motor coupled to a centrifugal pump. For different ambient conditions, different series parallel combinations of PV modules are tested and their performances are analyzed.

Analysis of Cascaded multilevel inverter

There is a new control strategy to control Cascaded multilevel converters in a multi-string configuration for single phase grid connected systems. This topology generates high quality output current under any circumstances specifically in partial shading, while tracking the MPP of each string independently. The topology does not consist of any extra DC-DC converter stage which causes some limitation in the performance but definitely reduces the overall cost and efficiency. Simulation results are provided to validate the proposed control system.

A novel fast mutable duty (FMD) MPPT technique for solar PV system with reduced searching area

In this paper, a novel maximum power point (MPP) tracking technique for photovoltaic system (PV) with fast convergence speed and reduced range for the MPP search operation is presented. The characteristic of this method is the limited searching area/range for the tracking. The adaptable variable duty step used in the proposed method instantaneously brings the operating point close to the MPP, thus bounding the searching area. The value of duty gets updated according to the panel temperature and irradiance, and the operating point always remains close to the MPP. By bounding the search operation, the overall tracking speed and efficiency of the tracking increase. Further enhancement of the tracking speed is obtained by varying the step size of duty ratio of the DC-DC converter used; this is done in such a manner that the size of variable duty step is large for the points far away from MPP and becomes very small at or near MPP. The projected tracking algorithm is compared with conventional Perturb and Obser...

Very Fast Measurement of Speed by Rotating Magnetic Field

For very low speed measurement, the output voltage of a tachometer type transducer and the voltage/noise ratio become very low. Moreover, it becomes stable only after several revolutions and it causes a delay of the order of several tens of second. In this work, a synchro based fast speed measurement technique is proposed. A balanced three-phase voltage is applied to the stator windings of synchro. It produces rotating magnetic field (RMF) which rotates at synchronous speed in the air gap. The induced emf generated in rotor of synchro and its frequency depend upon slip. The fast revolving RMF is used to measure the speed at very fast rate. A frequency meter connected at the output of rotor measures the frequency and hence speed. When RMF revolves at a speed, several times the speed of the rotor (which is physically coupled to the rotating member), the measurement becomes very fast. For very low speed of the rotor, the RMF rotates several times even before completion of one revolution of the rotor. Thus the output of synchro varies immediately and several times faster than the rotor itself. For lower speed and higher slip, the magnitude of the output voltage is unaffected, even at zero rpm. The scheme is very attractive for very low or super low speed for fast tracking and generation of feedback control signals.

Transient analysis and selection of perturbation parameters for PV-MPPT implementation

ABSTRACT In this article, system dynamics of a complete photovoltaic system have been studied. A small signal transient analysis model has been established to examine the effects of small change in the duty cycle of the converter as well as the time steps between each perturbation on the system dynamics. All efforts have been made to do a detailed analysis using almost all the equations involved. Sample calculations (using the simulated system model) are also shown so as to approximately analyse the perturbation effects. It is shown that the value of the step size of the duty cycle should be taken large for points far away from the maximum power point (MPP) and small for points near the MPP. Also, the time between two consecutive perturbations should be at least equal to the settling time. This article is very useful for the researchers to choose a proper delay between two consecutive perturbations and selection of the optimum value of the step size.

A comparative study and investigation of different diode models incorporating the partial shading effects

The paper holistically discusses the analysis and simulation of simplified two diode model and its comparative analysis with the one and three diode models. The two diode model presented has been grounded on the interpretation of the output current equation. This model entails four parameters and condenses the complexity and the computational time considerably. I-V and P-V curves for two diode model are plotted taking into account the variation of the atmospheric irradiance and temperature. Furthermore the two diode model is analysed by taking into account the effect of partial shading which plays an extremely detrimental role in the Solar Array output. A grave issue with partly shaded PV arrays is detouring of the maximum output voltage which acts to preponderate due to the manoeuvre of the bypass diodes present alongside the affected cell. This might cause a sizeable power loss, subject to the frequency of shading manifestation and thus leading to substantial reduction in the energy output of module. Paper presented scrutinizes the effects of six different Shading schemes on 6 × 6 array. Additionally it peers effects of Partial Shading on the different diode models in consideration. The characteristics of the diode models are comprehensively affected due to the presence of the shading effect. All the diode models for the investigation have been primed using the MATLAB simulation software. The values of various parameters used for comparison are presented in tabular form. The conclusions are deduced and the best model for simulation purpose is suggested taking into account the partial shading effect. From the outcomes and conclusions of this paper, it can be established that there exists a momentous loss in the output power because of the irregular irradiation pattern visible on the series strings.

A novel fast and accurate temperature tolerant PV Maximum Power Point tracking system

This paper presents a technique in determining the Maximum Power Output Point of the PV Panel under different Load, Temperature and Radiation Conditions. The technique is fast and precise for obtaining the Maximum Power Output of the PV Panel under sudden changes in Temperature and Irradiation conditions. The system uses the characteristics of the PV Panel for determining the effective load value across the panel for Maximum Power Output and adjusting it with the help of a Boost Converter to make the Panel work near the Maximum Power Point in changing conditions.