M.T. Iqbal

Modeling and control of a wind fuel cell hybrid energy system

This paper describes a hybrid energy system consisting of a 5 kW wind turbine and a fuel cell system. Such a system is expected to be a more efficient, zero emission alternative to wind diesel system. Dynamic modeling of various components of this isolated system is presented. Selection of control strategies and design of controllers for the system is described. Simnon is used for the simulation of this highly nonlinear system. Transient responses of the system for a step change in the electrical load and wind speed are presented. System simulation results for a pre-recorded wind speed data indicates the transients expected in such a system. Design, modeling, control and limitations of a wind fuel cell hybrid energy system are discussed.

A feasibility study of a zero energy home in Newfoundland

In a zero energy home annual energy consumption is equal to the annual energy production using one or more available renewable energy resources. In St John’s, Newfoundland wind is the readily available renewable energy resource. The average annual wind speed in St John’s is 6.7 m/s. This paper presents a feasibility study of a wind energy conversion system based zero energy home in Newfoundland. This study is based on year round recorded wind speed data, solar data and power-consumed data in a typical R-2000 house in Newfoundland. National Renewable Energy Laboratory’s software HOMER is used to select an optimum energy system. A detailed analysis, description and expected performance of the system are presented in this paper. This investigation indicates feasibility of a wind energy system based zero energy homes in Newfoundland.

Simulation of a small wind fuel cell hybrid energy system

This paper describes simulation results of a small 500 W wind fuel cell hybrid energy system. The system consists of a Southwest Wind Power Inc. AIR 403 wind turbine, a Proton Exchange Membrane Fuel Cell (PEMFC) and an electrolyzer. Dynamic modeling of various components of this small isolated system is presented. Simulink is used for the dynamic simulation of this nonlinear 48 V hybrid energy system. Transient responses of the system to a step change in the load current and wind speed in a number of possible situations are presented. Analysis of simulation results and limitations of a wind fuel cell hybrid energy system are discussed.

Reliability and condition monitoring of a wind turbine

Wind is one of the cheapest and cleanest sources of energy. However, large and frequent fluctuations in wind intensity and directions can cause serious problems in harvesting this energy. Wind turbines are subjected to many unexpected environmental loads, which can be catastrophic in nature for the wind turbine system. Like any other industrial equipment wind turbines also require some type of monitoring system which is able to predict the up coming faults of the most sensitive components of the system to save it from a major disaster. This paper highlights the ongoing research on reliability analysis and condition monitoring system required for a small-scale wind turbine system AOC15/50, which is widely used in Atlantic Canada and USA. The paper describes the importance of safety system and lay ground work for sensor specification, sensor mounting and configuration requirements for magnetic tip brake and yaw bearing which were proved to be the least reliable components in an extensive reliability analysis. The paper describes condition monitoring instrumentation, data acquisition system and data analysis methodology

Modeling and control of a small wind turbine

This paper starts with a detailed survey of control methods commonly employed by commercially available small wind turbines. This detailed survey indicates that the most commonly used control method of small wind turbines is horizontal furling method. Such furling mechanism and resulting dynamics are described in the paper. Furling is used to control the aerodynamic power extraction from the wind. A dynamic model of a small wind turbine with furling dynamics is presented in this paper. Such small wind turbines are based on permanent magnet generators and their speed can be regulated using the load control. The extraction of maximum power output from such wind turbines is investigated using tip speed ratio control and hill-climbing control methods. The system is simulated in Matlab/Simulink to determine a suitable control strategy. Two dynamic controllers are designed and simulated. In the first method, a controller uses the wind speed and rotor speed information and controls the load in order to operate the wind turbine at the optimum tip speed ratio. The generator output is observed in varying wind condition as the furl angle increases and decreases. In the second method, a controller compares the output power of the turbine with the previous power and based on the comparison it controls the load. Using a hill-climbing algorithm the controller tries to extract the maximum power from the wind, while the generator output is observed as the furl angle increase or decreases. Finally, the output of these two controllers is compared and investigated to determine which controller leads to the best results

Maximum Power Extraction from a Small Wind Turbine Emulator using a DC - DC Converter Controlled by a Microcontroller

An isolated small wind turbine emulator based on a separately excited DC motor is developed to emulate and evaluate the performance of a small wind turbine using different control strategies. The test rig consists of a 3HP separately excited DC motor coupled to a synchronous generator. A dump load is connected to the generator through a buck-boost converter controlled by a microcontroller. Wind turbine rotor and furling dynamics are incorporated in the emulator with the use of a PC based wind turbine model. Emulation of the wind turbine is confirmed by running the DC motor to track the theoretical rotational speed of the wind turbine rotor. A dynamic maximum power controller is implemented and tested. The controller uses the wind speed and rotor speed information to control the duty cycle of the buck-boost converter in order to operate the wind turbine at the optimum tip-speed ratio. Test results indicate that the proposed system accurately emulates the behavior of a small wind turbine system.

Design Considerations of a Straight Bladed Darrieus Rotor for River Current Turbines

Hydrokinetic turbines convert kinetic energy of moving river or tide water into electrical energy. In this work, design considerations of river current turbines are discussed with emphasis on straight bladed Darrieus rotors. Fluid dynamic analysis is carried out to predict the performance of the rotor. Discussions on a broad range of physical and operational conditions that may impact the design scenario are also presented. In addition, a systematic design procedure along with supporting information that would aid various decision making steps are outlined and illustrated by a design example. Finally, the scope for further work is highlighted

Development of a fuel cell simulator based on an experimentally derived model

Fuel cells (FC) are power sources that convert electrochemical energy into electrical energy in a clean and efficient manner. FC technology presents one of the most promising solutions to reduce fossil fuel consumption. FC simulators are expected to play a key role in the development of FC systems due to their low cost and flexibility. This paper presents the development of a stand-alone FC simulator based on a low cost digital signal processor (DSP). The proposed fuel cell simulator emulates the electrical dynamic behavior of a direct methanol fuel cell (DMFC) stack. This is achieved via a power converter with a robust control strategy with fast dynamic response. The reference signal for the power converter that represents the dynamic behavior of the FC is generated from an experimental model of the DMFC that can be extended to other FCs. The output of the FC simulator is a reproduction of the dynamic behavior of DMFC model, thus emulating a FC stack. Test results of the FC simulator and the actual FC are compared and discussed. From the viewpoint of educational purposes, the proposed FC simulator provides a flexible solution at a low cost for student and engineers in training. In addition, the proposed simulator can be used for the design and development of FC power electronics

A Technology Review and Simulation Based Performance Analysis of River Current Turbine Systems

River current turbines are electromechanical energy converters that harness kinetic energy of a stream of flowing river water to generate electricity. Research in this domain is limited and various concepts are emerging only recently. In this paper, an extensive technology survey and comparison of various system options are discussed in order to formulate a basis for further analysis. Simplified mathematical modeling of an augmentation device and Darrieus type rotor has been carried out. Simulations are done in Matlab and results are given with graphical interpretations. In conclusion, directions for further investigation are given and the potential of this technology is re-stressed

Design and development of hybrid vertical axis turbine

Power from wind or water current can be extracted using a horizontal or vertical axis turbine. Vertical axis turbines are capable of extracting power from wind or water current regardless of the direction of flow. A hybrid turbine consists of two types of turbines on a same shaft. Such a design exploits good features of two turbines. This paper presents the design of a hybrid turbine based on a straight bladed Darrieus (lift type) turbine along with a double step Savonius (drag type) turbine. Four bladed Darrieus rotor is placed on top of a Savonius rotor. The hybrid vertical axis turbine has much better self-starting characteristics and better conversion efficiency at higher flow speeds. The hybrid turbine is built and tested in variable speed water currents. This turbine design can also be used as a wind turbine. This paper presents the system design and performance test results of the hybrid turbine. The designed hybrid vertical axis turbine will be used to generate power at the sea floor for an instrumentation system.