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Design of Wind Dominated Hybrid Remote Area Power Supply Systems Nishad Mendis University of Wollongong

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Design of Wind Dominated Hybrid Remote Area Power Supply Systems Nishad Mendis University of Wollongong University of Wollongong Research Online University of Wollongong Thesis Collection University of Wollongong Thesis Collections 2012 Design of Wind Dominated Hybrid Remote Area Power Supply Systems Nishad Mendis University of Wollongong Recommended Citation Mendis, Nishad, Design of Wind Dominated Hybrid Remote Area Power Supply Systems, Doctor of Philosophy thesis, School of Electrical, Computer and Telecommunications Engineering, University of Wollongong, 2012. http://ro.uow.edu.au/theses/3489 Research Online is the open access institutional repository for the University of Wollongong. For further information contact the UOW Library: [email protected] Design of Wind Dominated Hybrid Remote Area Power Supply Systems A thesis submitted in fulfilment of the requirements for the award of the degree Doctor of Philosophy from University of Wollongong by Nishad Mendis, BSc(Eng) School of Electrical, Computer and Telecommunications Engineering April 2012 Dedicated to my parents... Acknowledgements This thesis would not have become a realisation without the contributions from many people and institutions. Foremost, I would like to express my sincere gratitude to my main supervisor A/Prof. Kashem M. Muttaqi for offering a timely and interesting research topic. Besides my main supervisor, I would like to thank my co-supervisor A/Prof. Sarath Perera for giving me an opportunity to pursue my doctoral studies at the University of Wollongong (UOW). I appreciate their patience, motivation, enthusiasm, and im- mense knowledge, moral support and guidance helped me throughout the research and writing of this thesis. The project was financially funded by Australian Research Council (ARC) and Hydro Tasmania Linkage Grant, LP0669245. I extremely grateful for this generous support, as well as the financial assistance provided by the Endeavor Energy Power Quality and Reliability Centre (EEPQRC). I would like to thank Dr. Saad S. Sayeef, former post doctoral fellow at EEPQRC in addition for his insight technical contributions and friendly attitude. Also, a spe- cial thank goes to Dr Sridhar R. Pulikanti for his guidance provided me during the last year of my PhD research. Thanks to Dr. Ashish Agalgaonkar and Dr. Lasanatha Meegahapola for the assistance provided. I am indebted to Dr. Vick Smith, Gerrard Drury, Sean Elphick and Esperanza Gonzalez who are with EEPQRC at UOW, given their immense support for administrative and software related matters. Many thanks also goes to Roslyn Causer-Temby and Sasha Nikolic of the School of Electrical, Com- puter and Telecommunications Engineering (SECTE) at UOW, involved in solving administrative related problems and providing perspectives. The technical assistance provided by the SECTE technical staff is highly appreciated. I’m extremely thankful for Dilini Kumarasinghe for her support and encourage- iii iv ment provided during the writing of this thesis. A special thanks go to my friends Dr. Sankika Tennakoon and Dr. Prabodha Paranavithana, previously with the EEP- QRC, and Radley De Silva, Kalyani Dissanayake, Upuli Jayathuga, Devinda Perera, Dothinka Ranamuka, Brian Perera, Vidarshika Jayawardene, Kai Zou and Yinchin Choo for being supportive in many ways especially during the hard times along the way. Finally and most importantly, my heartiest gratitude goes to my parents, sis- ter and brother-in-law, niece and my wonderful relatives for their encouragement, guidance all the sacrifices you all made on behalf of me. Certification I, Nishad Mendis declare that this thesis, submitted in fulfilment of the requirements for the award of Doctor of Philosophy, in the School of Electrical, Computer and Telecommunications Engineering, University of Wollongong, is entirely my own work unless otherwise referenced or acknowledged. This manuscript has not been submit- ted for qualifications at any other academic institute. Nishad Mendis v Abstract Hybrid remote area power supply (RAPS) systems can be regarded as an emerging power generation technology for rural and remote communities. These power systems combine the best features of conventional (e.g. diesel based power generation) and non-conventional (e.g. renewable energy) power generation technologies. Hybridi- sation of such energy sources provides superior performance in terms of efficiency, lower carbon emission levels, reduced generation cost and improved supply quality and reliability. Although hybrid RAPS systems seem to offer promising solutions, there are vari- ous challenges associated with design and operation of such generating schemes which include: (a) voltage and frequency regulation on customer side, (b) control coordina- tion between the system components (e.g. energy storage, dump load), (c) develop- ment of individual control strategies for each system component and (d) maximum power extraction from renewable energy resources. This thesis addresses the above stated issues in relation to wind based RAPS systems where the wind turbine gen- erator performs as the main source of energy. In this regard, two types of popular wind turbine generator technologies, namely: doubly fed induction generator (DFIG) and permanent magnet synchronous generator (PMSG) are considered to form RAPS systems. In addition, auxiliary system components such as an energy storage system, dump load and other types of generating schemes including diesel and hydrogen are combined with wind turbine generator to perform the hybrid operation. Robust control strategies are developed for the converter systems of the wind tur- bine generators with a view to regulate the voltage and frequency on the load side. In addition, a battery storage system and a dump load are integrated to regulate the power balance of the RAPS systems. Moreover, separate configurations of the dump load are proposed for DFIG based and PMSG based RAPS systems. Individual vi vii controllers are implemented for the battery storage systems and dump loads whose op- eration is managed through a coordinated control approach. The coordinated control approach is designed to perform as an integrated controller of the RAPS system which manages the power flow between the system components and coordinate responses of individual components in a designated manner. In addition, control strategies are developed to operate the wind turbine generators on their maximum power tracking characteristics to ensure optimum system performance. Operation of a battery storage system is coordinated with a supercapacitor with a view to improve the battery life by reducing ripple content of battery current. Two different power electronic configurations are proposed to interface the hybrid energy storage (i.e. battery storage and supercapacitor) of DFIG based and PMSG based RAPS systems. The operation of the hybrid energy storage system is coordinated through the implementation of an energy management algorithm which is developed with a view to reduce the depth of discharge and ripple content of the battery current. Applicability of a dual mode operation of diesel generating system (i.e. either as a synchronous condenser or as synchronous generator) for wind based RAPS system is examined. The dual mode operating mechanism is controlled via a friction clutch that helps to improve the fuel economy by avoiding the low load factor operation of the diesel generating scheme. Technical viability of such a diesel generating scheme is implemented giving due consideration to its modelling aspects together with respec- tive controllers. Also, reactive power management schemes are implemented between the wind energy conversion system and diesel generating system. To improve the autonomy of operation of the RAPS systems, hydrogen based gen- erating schemes are introduced. In this regard, the technical feasibility of integrating a hydrogen based generating system consisting of a fuel cell system, an electrolyser and a storage tank to a wind based RAPS system is examined. Individual control viii strategies are implemented for each component of the hydrogen storage system and their functions are coordinated to perform as a self generating unit. The performance evaluation utilising linearised component based RAPS system is also undertaken with a view to compare the results that are obtained using the corre- sponding detailed models. Above stated DFIG based and PMSG based RAPS systems are also investigated under changing wind and varying load conditions. Through sim- ulation studies it is revealed that the proposed control strategies developed for the RAPS systems are capable in regulating the voltage and frequency on the load side while extracting the maximum power from wind. List of Principal Symbols and Abbreviations ρ Air density in Kgm−3 A Area swept by the rotor blades in m2 ib Battery current Pb Battery power output vb Battery voltage Csup Capacitance of the supercapacitor in F −1 (vw)cut−in Cut-in wind speed in ms −1 (vw)cut−out Cut-out wind speed in ms D Damping constant vdc DC bus voltage ωd Diesel engine speed Pde Diesel power output Pd Dump load power vds, vqs d and q axes voltage on load side vdr, vqr d and q axes voltage on rotor side of the DFIG φds, φqs d and q axes stator flux components of DFIG φdr, φqr d and q axes rotor flux components of DFIG ielz Electrolyser current Pelz Electrolyser power consumption Te Electrical torque of wind turbine generator velz Electrolyser voltage F Faraday constant in Ckmol−1 ηF Faraday efficiency Lf Filter inductance ∆f Frequency deviation ix x Pfc Fuel cell power output fs Frequency on load side ifc Fuel cell current
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