HVDC TRANSMISSION Power Conversion Applications in Power Systems HVDC Transmission: Power Conversion Applications in Power Systems Chan-Ki Kim, Vijay K. Sood, Gil-Soo Jang, Seong-Joo Lim and Seok-Jin Lee © 2009 John Wiley & Sons (Asia) Pte Ltd. ISBN: 978-0-470-82295-1 HVDC TRANSMISSION Power Conversion Applications in Power Systems Chan-Ki Kim KoreaElectricPowerCorporation,KoreaElectricPowerResearchInstitute Vijay K. Sood UniversityofOntarioInstituteofTechnology Gil-Soo Jang KoreaUniversity Seong-Joo Lim KoreaElectricPowerCorporation Seok-Jin Lee KoreaElectricPowerCorporation Copyright#2009 JohnWiley&Sons(Asia)PteLtd,2ClementiLoop,#02-01, Singapore129809 VisitourHomePageonwww.wiley.com AllRightsReserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystemortransmittedin anyformorbyanymeans,electronic,mechanical,photocopying,recording,scanning,orotherwise,exceptas expresslypermittedbylaw,withouteitherthepriorwrittenpermissionofthePublisher,orauthorization throughpaymentoftheappropriatephotocopyfeetotheCopyrightClearanceCenter.Requestsforpermission shouldbeaddressedtothePublisher,JohnWiley&Sons(Asia)PteLtd,2ClementiLoop,#02-01,Singapore 129809,tel:65-64632400,fax:65-64646912,email:[email protected]. 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Contents Foreword ix Preface xi Acknowledgments xiii Author Biographies xv List of Symbols xix 1 Development of HVDC Technology 1 1.1 Introduction 1 1.2 Advantages of HVDC Systems 3 1.3 HVDC System Costs 7 1.4 Overview and Organization of HVDC Systems 13 1.5 Review of the HVDC System Reliability 19 1.6 HVDC Characteristics and Economic Aspects 30 References 34 2 Power Conversion 37 2.1 Thyristor 37 2.2 3-Phase Converter 47 2.3 3-Phase Full Bridge Converter 54 2.4 12-Pulse Converter 58 References 61 3 Harmonics of HVDC and Removal 63 3.1 Introduction 63 3.2 Determination of Resulting Harmonic Impedance 81 3.3 Active Power Filter 87 References 95 4 Control of HVDC Converter and System 97 4.1 Converter Control for an HVDC System 97 4.2 Commutation Failure 110 vi Contents 4.3 HVDC Control and Design 116 4.4 HVDC Control Functions 130 4.5 Reactive Power and Voltage Stability 137 4.6 Summary 145 References 145 5 Interactions between AC and DC Systems 149 5.1 Definition of Short Circuit Ratio and Effective Short Circuit Ratio 149 5.2 Interaction between HVDC and AC Power System 159 References 184 6 Main Circuit Design 187 6.1 Converter Circuit and Components 187 6.2 Converter Transformer 193 6.3 Cooling System 200 6.4 HVDC Overhead Line 213 6.5 HVDC Earth Electrodes 229 6.6 HVDC Cable 235 6.7 HVDC Telecommunications 243 6.8 Current Sensors 249 6.9 HVDC Noise and Vibration 251 References 255 7 Fault Behavior and Protection of HVDC System 257 7.1 Valve Protection Functions 257 7.2 Protective Action of an HVDC System 260 7.3 Protection by Control Actions 268 7.4 Fault Analysis 274 References 277 8 Insulation Coordination of HVDC 279 8.1 Surge Arrester 279 8.2 Functions of the Arresters in an HVDC Station 282 8.3 Insulation Coordination of the Cheju HVDC System 288 References 293 9 A Practical Example of an HVDC System 295 9.1 Introduction 295 9.2 System Description 301 9.3 Phase Control 304 References 327 10 Other Converter Configurations for HVDC Transmission 329 10.1 Introduction 329 10.2 Voltage Source Converter (VSC) 329 Contents vii 10.3 CCC and CSCC HVDC System 340 10.4 Multi-Terminal DC Transmission 349 References 357 11 Modeling and Simulation of HVDC Systems 359 11.1 Simulation Scope and Range 359 11.2 Fast Methods for Accurate Simulation 363 11.3 HVDC Modeling and Simulation 368 11.4 Cheju–Haenam HVDC Real-Time Digital Simulator 373 References 381 12 Present and Proposed Future Installations of HVDC Systems 383 12.1 USA 383 12.2 Japan 387 12.3 Europe 389 12.4 China 396 12.5 India 397 12.6 Malaysia/Philippines 398 12.7 Australia/New Zealand 399 12.8 Brazil 400 12.9 Africa 401 13 Trends for HVDC Applications 403 13.1 Wind Farm Technology 403 13.2 Modern Voltage Source Converter (VSC) HVDC Systems 413 13.3 800 kV HVDC System 422 References 431 Index 433 Foreword TenyearsagoKoreabegantheoperationofitsfirstHVDC system,linkingChejuIslandtoHaenamonthemainland.It wasanextremelyimportantcontributiontoourindustry.In the future, issuessuch as systemic links and the quality of largescale,renewableenergywillbecomecrucial.HVDCis criticaltosolvingthesemajorconcerns,Iamproudtobea part ofthat project. This book, a compendium of work relating to HVDC technology, is a key resource. Enormous effort has been undertakentoproducethisgreatbodyofmaterialinsucha short period oftime. In our industry, we must acknowledge the inevitable depletion of fossil fuels and the growing importance of environmentalawareness.Assuch,electricityoffersanum- berofadvantagesintermsofefficiency,economy,andcleanenergy,especiallycomparedto coal, oil, and gas. HVDC can resolve a number of issues, including voltage stability in alternating current systems, reducing growing fault currents, and increasing electric power reserves. Clearly, it plays a crucial rolein the future of electricpower. Mostsignificantly,HVDCisthemosteffectivesolutioninareaswhichrequirehighquality electricity orlinks tolargescale renewable resources. This book encompasses a number of studies which cover basic and advanced HVDC applications,allconductedunderthesupervisionofworld-renownedexperts.Withoutdoubt, thisisoneofthebestvolumesofinformationavailableforHVDCtechnology.Sciencehasno boundaries, so I believe that this book will be a useful resource and beneficial to electric industries around theworld. Isincerelyhopethattheauthorsofthisbookcontinuetodedicatetheirvastskillsandefforts tofurther research inthe HVDC field. x Foreword I’m reminded of the tireless dedication of researchers I worked with when I was the president at KEPRI. They had a slogan written across their desks that 1 believe in whole heartedly. It said: HVDC will bring benefits and improvementto theworld! Korea Electric Power Corporation Transmission Division Senior Vice-President Kim, Moon-Duk Preface Although HVDC transmission is considered to be a mature technology by some, it is quite amazing how many new aspects and projects are under consideration. The complexity of electricalpowersystemsisincreasingowingtoitsinterconnectionswithexistingsystemsand applicationofnewtechnologyandatthesametime,manyeconomicandotherconstraintsare forcing the utilities to operate their system near the maximal limits of stability and provide realiableandcleanpoweratthelowestcost.IndevelopingnationssuchasChina,India,and Brazil,theongoingdemandforpowerisforcingtheneedforHVDCbulkpowertransmission over long distances. Developed nations wishing to interconnect networks and provide flexibility are relying on HVDC B-to-B connections. Furthermore, there is growing interest toincorporaterenewableenergysourcesintothegrid,againrelyingonHVDClinks.Itseems thatapplicationsofHVDCtransmissiontechnologyarenecessaryasameanstoovercomesuch problems. The history of DC transmission began in 1897 when Thomas Edison succeeded in implementing the supply and consumption of electricity at a low DC voltage. At that time, thetechnologicalstandardsforelectricalpowerindustrieswerestillbeingdevelopedandthe technologicalcompetitionbetweentheDCpowertransmissionandtheACpowertransmission method through transformers, developedby GeorgeWestinghouse, were quite severe. Subsequently,large-scalegenerationandtransmissionofelectricitywasinhighdemandas people began to realize its importance. Since AC technology was superior in terms of generation, reliability, transformation, and transmissionvoltage, it became the backbone of theelectricpowerindustry.Ontheotherhand,DCtransmissiongainedrespectonlyafterthe development of the mercury arc valve in the 1930s. The HVDC type of electrical power transmission began its first commercial operation in Gotland, Sweden in 1954 through a submarinecable interconnection. TheuniquecharacteristicsofHVDCtransmissioncontinuedtomakethetechnologyviable forspecialnicheapplications.Intheearly1970s,theadventofthethyristorvalvegaveaboost totheapplicationsofHVDCandconsiderablyenhancedreliabilityandloweredthecostsof implementation. The availability of high power forced commutated switches in the 1990s further enhanced the applications for HVDC. Today, the technology of HVDC is well established and operates in partnership with FACTS-based AC transmission to provide complexandversatilemodesofpowertransmission.However,newapplications arealways beingdeveloped.Itisimportant,therefore,thatthetechnologycontinuestobedevelopedtoo and that new researchers and engineers continue to understand this technology. We find, however,thattheliteratureonthissubjectisoftenlackingandnotavailableinacomprehensive xii Preface manner.Consequently,itwasfeltthatpracticingengineersshouldaddtheirexpertisetothis informationpool for upcominggenerations. TheKoreaElectricPowerCorporation(KEPCO)iscurrentlyactivelypursuinganelectrical power interconnection project encompassing the North-East Asian region domestically and abroad.Theengineers,whohavemanyyearsofpracticalexperiencebehindthem,gottogether topreparethistextbook.Asaresultoftheirfirst-handknowledgeoftheactualstationbetween Cheju and Haenam, this text combines practical and theoretical knowhow not available elsewhere on the subject of HVDC transmission. InChapters1and2,weprovideanintroductiontoDCpowertransmissionanddescribethe basiccomponentsofaconverter,whichisthemostessentialelementforHVDCtransmission. Inaddition,wedescribethemethodsforcompensatingthereactivepowerdemandedbythe converterand the methods for simulation ofHVDC systems. In Chapters 3–5, we have described the types of filters for removing harmonics and the characteristicsofthesystemimpedanceresultingfromACfilterdesigns.Wealsodescribethe IPC(IndividualPhaseControl)method,whichisthebasicmethodtocontrolthephaseofa thyristor,aswellastheEPC(EquidistantPulseControl)methodandtheDCsystemcontrol method. InChapters6–8,thedesigntechniquesforthemaincomponentsofanHVDCsystemare described: thyristor converters, converter transformers, smoothing reactors, overhead lines, cable lines, ground electrodes, andBack-to-Backconverters. InChapters9–10,DCandACtransmission,intermsoftheircapacityofpowertransmission, environmental impact, and economical characteristics, are compared. Based on the actual applicationofelectricalpowertransmission,wehavefullydescribedthecurrentstatusofthe HVDCtypeofelectricalpowertransmissiontechnologyandthetrendforHVDCtechnologies aroundtheworld. Useful supplements for this title are available on the book’s companion website at the following URL: http://www.wiley.com/go/hvdc. Itisoursincerehopethatthistextwilladdtothewealthofliteratureavailableonthesubject ofHVDC transmission. Wedo realize thatit is notpossibletocover allaspects ofthis vast technology, although we havetried tobring ina practical focus notavailableelsewhere. Chan-Ki Kim VijayK. Sood Gil-SooJang Seong-Joo Lim Seok-JinLee