S. Arul Daniel

MPPT With Single DC–DC Converter and Inverter for Grid-Connected Hybrid Wind-Driven PMSG–PV System

A new topology of a hybrid distributed generator based on photovoltaic and wind-driven permanent magnet synchronous generator is proposed. In this generator, the sources are connected together to the grid with the help of only a single boost converter followed by an inverter. Thus, compared to earlier schemes, the proposed scheme has fewer power converters. A model of the proposed scheme in the d-q-axis reference frame is developed. Two low-cost controllers are also proposed for the new hybrid scheme to separately trigger the dc-dc converter and the inverter for tracking the maximum power from both sources. The integrated operations of both proposed controllers for different conditions are demonstrated through simulation and experimentation. The steady-state performance of the system and the transient response of the controllers are also presented to demonstrate the successful operation of the new hybrid system. Comparisons of experimental and simulation results are given to validate the simulation model.

Voltage Control of an Autonomous Hybrid Generation Scheme Based on PV Array and Wind-Driven Induction Generators

Hybrid distributed generators are increasingly found to supply reliable power in isolated locations. In this article, a DC-DC step-up converter for maintaining a constant load voltage in a hybrid PV array excited wind-driven induction generator is proposed. A closed loop PI controller is designed to automatically vary the duty-cycle of the DC-DC converter. A dynamic d-q axes model of the entire scheme is presented. Constant voltage regimes for varying irradiation and wind speed are obtained using the developed model. Further, close agreement between the experimental and simulated waveforms is established to demonstrate the veracity of the simulation.

Design methodology for autonomous operation of a Micro-grid

The operation of a radial distribution network in an islanded mode has become significant due to an increase in the integration of renewable sources to the utility network. In this project, a computational tool is presented to design the sizes of the distributed resources for an autonomous micro-grid operation of a radial distributor. The technique employs GA optimization, considers the variation in generation and demands in summer and winter. The presented load flow solutions of the designed islanded-Micro-grid shows that the node voltages are within the specified limits during summer and winter.

Computational Techniques for Autonomous Microgrid Load Flow Analysis

This paper attempts at developing simple, efficient, and fast converging load flow analysis techniques tailored to autonomous microgrids. Two modified backward forward sweep techniques have been developed in this work where the largest generator is chosen as slack generator, in the first method and all generator buses are modeled as slack buses in the second method. The second method incorporates the concept of distributed slack bus to update the real and reactive power generations in the microgrid. This paper has details on the development of these two methodologies and the efficacy of these methods is compared with the conventional Newton Raphson load flow method. The standard 33-bus distribution system has been transformed into an autonomous microgrid and used for evaluation of the proposed load flow methodologies. Matlab coding has been developed for validating the results.

Optimal sizing of hybrid generators for autonomous operation of a micro-grid

As a matter of fact, there is an ever increasing need for augmenting renewable resources to the existing power system in order to meet its increasing demand. These resources are generally connected to the distribution network, thereby alleviating the stress on the network and also providing the necessary reliability. A distribution network with renewable and fossil-based resources is a micro-grid. Such a micro-grid may be operated either in Autonomous (isolated from the utility grid) or Non-Autonomous (connected to the grid) mode of operation. This paper attempts to develop an algorithm to determine the sizes of the renewable resources for autonomous operation of the micro-grid using Particle Swarm Optimization and Modified Genetic Algorithm based optimization techniques. MATLAB code has been developed and sizing of generators for a standard 33 bus distribution system has been presented to demonstrate the utility of the methodology.

Analog controller for photovoltaic array fed inverter driven single-phase induction motor

PV array is increasingly employed for water pumping system. In this project, a controller to vary the amplitude of the inverter output voltage interposed between the PV array and single phase induction motor is developed. The detailed modeling of the components of proposed scheme has been taken up. The developed controller varies the pulse-width of a SPWM generator, so that that the inverter output voltage varies with irradiation and temperature. The variation of the amplitude is to maximize the power output (speed) for a given irradiation and temperature. Experimental investigation presented gives the utility of such a control approach.

Simulation of Photovoltaic Array-driven Electric Machines with Power Electronic Interfaces

Power electronic interfaces between photovoltaic (PV) arrays and electric machines are necessary in order to match the drive characteristics with the characteristics of the array for efficient utilization of the resource. This paper proposes a model for the simulation of a complete solar PV power electronic conversion system in circuit simulation software, where a model of a PV array is not readily available in their libraries. The proposed circuit-based PV model is employed to simulate the waveforms of a direct current (DC) motor and induction motor drive system fed by a chopper and inverter, respectively. Close resemblance between experimental and simulated waveforms is established to validate the simulation. A quasi-stationary approach for simulating the dynamics of a PV-fed drive with temperature and irradiation variation has also been implemented in the simulation model. The details of the design of a fuzzy controller based on the simulation and its validation are also presented in this paper.Power electronic interfaces between photovoltaic (PV) arrays and electric machines are necessary in order to match the drive characteristics with the characteristics of the array for efficient utilization of the resource. This paper proposes a model for the simulation of a complete solar PV power electronic conversion system in circuit simulation software, where a model of a PV array is not readily available in their libraries. The proposed circuit-based PV model is employed to simulate the waveforms of a direct current (DC) motor and induction motor drive system fed by a chopper and inverter, respectively. Close resemblance between experimental and simulated waveforms is established to validate the simulation. A quasi-stationary approach for simulating the dynamics of a PV-fed drive with temperature and irradiation variation has also been implemented in the simulation model. The details of the design of a fuzzy controller based on the simulation and its validation are also presented in this paper.

A comparative review on small scale integration of hybrid fuel cell and PV generating system to utility network

A comparative review is presented for integrated PEM Fuel Cell and Photovoltaic generating system to single phase utility grid. Different techniques of common coupling for integration have been investigated for this system. For both common AC bus and Common DC bus integration schemes, two different current control techniques have been investigated. The simulation result shows that common DC bus integration with PI current controller in series hysteresis limiter has less harmonics and more efficient than conventional current controller and Common AC bus Integration.

Hybrid Analyzing Technique for Active Islanding Detection Based on d-Axis Current Injection

Detection of islanded operation of distributed generators has become very important for ensuring the safety of the service personnel and electrical components. In this paper, a deliberate disturbance in the d-axis current of the generator is used for active island detection. A novel hybrid analyzing technique is proposed, which analyses the d-axis voltage component in two different ways to detect islanding accurately. It is shown that the proposed hybrid analyzing technique utilizes the time-tested d-axis current disturbance injection in an attempt to detect islanding faster without causing any threat to the stability of the distributed generator. It has also been established that the proposed technique avoids any malidentification of islanding and distinguishes accurately the switching and other transients from an islanded operation. MATLAB/Simulink platform has been used to validate the proposed method of islanding detection on various operating conditions.

Feasibility studies of rooftop photovoltaic (PV) systems for domestic consumers in rural India

Rural areas in India are generally fed from a weak distribution network and hence power is supplied with prohibitively low voltage to the consumer. Installation of Rooftop PhotoVoltaic systems in every household can help mitigate this problem. However, the deployment of such RTPV is abysmally low in rural India. The economics and feasibility of such RTPV need careful study. In this paper, such a study of a RTPV system for a domestic consumer in rural areas of India are examined. The major work is focussed on PV sizing for an on-line grid-connected PV system for a rural household without battery storage. The tariff structure of the Tamil Nadu Electricity Regulatory Commision has been utilized for the cost calculations, and the pay back period has been obtained for a rural consumer. Six parameters of the system were analyzed based on PV sizing and the internal rate of return. Our finding show that an effective choice of PV sizing helps to achieve positive cash flow, leading to electricity bill savings, which in turn helps to achieve a shorter pay back period and net zero energy operation.