EHV/HV Underground Cable Systems for Power Transmission

Publikation: Bog/antologi/afhandling/rapportPh.d.-afhandlingForskning

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Resumé

El transmissionsnettet står overfor den største udfordring nogensinde når den voksende mængde af fornybare el‐produktionsanlæg skal erstatte de nuværende, der er baseret på afbrænding af fossile brændsler. Det er ikke længere muligt at placere kraftværker tæt på store forbrugscentre såsom byer og industrianlæg. Disse må nødvendigvis placeres der, hvor de fornybare ressourcer er tilgængelige. Et eksempel herpå er offshore vindkraftværker.

Transmissionsnettet er traditionelt designet til ikke at skulle overføre store mængder energi over lange og varierende strækninger, i det el‐produktionen var lokaliseret hvor forbruget også var. Transmissionsnettes rolle har mere været som et samarbejdsnet, der har sikret en rimelig pålidelighed og redundans med hensyn til forsyning.

Fremtidens transmissionsnet skal kunne håndtere de mange forskellige og effektvarierende fornybare elproduktionsanlæg, der planlægges og samtidig kunne fungere på markedsvilkår. Dette medfører, at transmissionsnettets nuværende topologi skal gentænkes for at kunne opfylde fremtidens krav til transmissionsnettet. Der skal bygges nye linjer.

Transmissionslinjer udføres normalt som luftledningsanlæg, der er vældig store og dominerende i deres omgivelser. For eksempel er en 400 kV luftledningsmast 50 meter høj. Befolkningen udviser en langvarig og stigende utryghed overfor luftledningsanlæg og modstanden mod nye anlæg er massiv. Vi er nødt til at komme med alternativer til luftledningsanlæg, som befolkningen kan acceptere. Nedgravede kabelanlæg opfylder dette ønske, men er på mange måder uprøvet teknologi for el‐transmission. Der er behov for ny forskning for at kunne skabe de retningslinjer, som et teknisk forsvarligt design af sådanne bygger på.

Denne afhandling præsenterer 10 års forskningsresultater for kabeltransmissionsnet for et forskningssamarbejde mellem den danske transmissionssystemoperatør Energinet.dk og Institut for Energiteknik, Aalborg Universitet. Afhandlingen er baseret på et antal udvalgte publikationer, og den summerer og fremhæver resultaterne fra disse på et formidlingsniveau, der er tiltænkt som værende lettere tilgængeligt end den videnskabeligt “normale” formidling i publikationerne. Dette giver mening, da afhandlingen præsenterer mange resultater fremfor detaljerne i enkelte resultater, hvorfor disse må skulle formidles bredere. Resultaterne er valgt fra deres videnskabelige kontekst i publikationerne og søgt formidlet, så de er nemmere tilgængelige for denne afhandlings læsere. Den fuldstændige beskrivelse af baggrunden for hvert enkelt forskningsresultat kan findes i publikationerne.

Først gennemgås de tekniske udfordringer, som opstår, når man vil anvende kabler til el‐transmission, derefter modeldannelse og validering i tidsdomænet, derefter følger hovedvægten af det udførte arbejde, hvilket er dynamiske forhold for kabeltransmissionsanlæg. Der opstilles teori og eksempelstudier for de forskellige designstudier, der skal gennemgås, for at et komplet design kan gennemføres. Herefter gennemgås beskyttelse og fejllokalisering og afhandlingen afsluttes med konklusion og forslag til fremtidigt arbejde. Til slut findes en litteraturliste samt de publikationer, afhandlingen er baseret på.

Det konkluderes, at nedgravede kabelanlæg er en teknisk mulig løsning til el‐transmission, selv om konsekvenserne af ovennævnte, nye designregler ikke er kendt på langt sigt. Der fremstår mange interessante, fremtidige forskningsemner, specielt indenfor asset management værktøjer.
OriginalsprogEngelsk
ForlagDepartment of Energy Technology, Aalborg University
Antal sider472
ISBN (Trykt)978‐87‐92846‐54‐9
StatusUdgivet - 2015

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Underground cables
Power transmission
Power plants
Electric lines
Cable cores
Overhead lines
Asset management
Electric fault location
Bibliographies
Natural resources
Wind power
Redundancy

Citer dette

Bak, C. L. (2015). EHV/HV Underground Cable Systems for Power Transmission. Department of Energy Technology, Aalborg University.
Bak, Claus Leth. / EHV/HV Underground Cable Systems for Power Transmission. Department of Energy Technology, Aalborg University, 2015. 472 s.
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title = "EHV/HV Underground Cable Systems for Power Transmission",
abstract = "Power transmission is facing its largest challenges ever with regards to handling a transition from today’s fossil‐based power production into renewable sources of generation. We can no longer place power plants close to centres of consumption; they must be located where the natural resources are to be found. One very good example of this is offshore wind power plants.The current transmission system is laid out in a traditional manner, which is based on the idea of not transporting power over longer distances as the power plants have been located near centres of consumption. It has merely played the role of interconnecting these generation/load centres, ensuring fair reliability and redundancy of supply.Nowadays, the power transmission system must be able to handle the various sources of renewable generation in a flexible electricity market. This has the consequence that the original layout of the transmission system must be re‐thought in order to accommodate the transmission needs for the future. New lines have to be constructed.Transmission lines are usually laid out as overhead lines, which are large structures, i.e. a 400 kV power pylon is 50 meters high. According to public opinion, such power lines are undesirable. Therefore, we must come up with an alternative, acceptable to the public.Underground cables fulfil the above mentioned need to be more publically acceptable, but, for long transmission lines, they are in many ways unproven. Guidelines for their design are needed.This thesis presents the results of a decade of underground cable research studies performed in Denmark by Danish TSO Energinet.dk and the Department of Energy Technology.The thesis is based upon a number of selected publications and summarises the results of these at a presentation level intended to have an easier, possibly less scientific touch. The results are taken from their scientific embedding in the papers and made more easily accessible to readers of the thesis. The full theoretical background is to be found in the papers and their references.Firstly, an introduction to the challenges when using underground cables is given, and secondly, the modelling approach and validation of this is discussed. Thirdly, making up the main core of the work presented, dynamics of underground cable systems are discussed and important cases to study are highlighted, and next, protection and fault location are discussed. The thesis ends with conclusions and future works, a bibliography and the publications upon which it is based.It is concluded that underground cable systems are technically possible for power transmission, although the maturity of the consequences of the newly made design guidelines are still in its youth. Many interesting research topics are still open, especially with regards to asset management tools.",
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Bak, CL 2015, EHV/HV Underground Cable Systems for Power Transmission. Department of Energy Technology, Aalborg University.

EHV/HV Underground Cable Systems for Power Transmission. / Bak, Claus Leth.

Department of Energy Technology, Aalborg University, 2015. 472 s.

Publikation: Bog/antologi/afhandling/rapportPh.d.-afhandlingForskning

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T1 - EHV/HV Underground Cable Systems for Power Transmission

AU - Bak, Claus Leth

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N2 - Power transmission is facing its largest challenges ever with regards to handling a transition from today’s fossil‐based power production into renewable sources of generation. We can no longer place power plants close to centres of consumption; they must be located where the natural resources are to be found. One very good example of this is offshore wind power plants.The current transmission system is laid out in a traditional manner, which is based on the idea of not transporting power over longer distances as the power plants have been located near centres of consumption. It has merely played the role of interconnecting these generation/load centres, ensuring fair reliability and redundancy of supply.Nowadays, the power transmission system must be able to handle the various sources of renewable generation in a flexible electricity market. This has the consequence that the original layout of the transmission system must be re‐thought in order to accommodate the transmission needs for the future. New lines have to be constructed.Transmission lines are usually laid out as overhead lines, which are large structures, i.e. a 400 kV power pylon is 50 meters high. According to public opinion, such power lines are undesirable. Therefore, we must come up with an alternative, acceptable to the public.Underground cables fulfil the above mentioned need to be more publically acceptable, but, for long transmission lines, they are in many ways unproven. Guidelines for their design are needed.This thesis presents the results of a decade of underground cable research studies performed in Denmark by Danish TSO Energinet.dk and the Department of Energy Technology.The thesis is based upon a number of selected publications and summarises the results of these at a presentation level intended to have an easier, possibly less scientific touch. The results are taken from their scientific embedding in the papers and made more easily accessible to readers of the thesis. The full theoretical background is to be found in the papers and their references.Firstly, an introduction to the challenges when using underground cables is given, and secondly, the modelling approach and validation of this is discussed. Thirdly, making up the main core of the work presented, dynamics of underground cable systems are discussed and important cases to study are highlighted, and next, protection and fault location are discussed. The thesis ends with conclusions and future works, a bibliography and the publications upon which it is based.It is concluded that underground cable systems are technically possible for power transmission, although the maturity of the consequences of the newly made design guidelines are still in its youth. Many interesting research topics are still open, especially with regards to asset management tools.

AB - Power transmission is facing its largest challenges ever with regards to handling a transition from today’s fossil‐based power production into renewable sources of generation. We can no longer place power plants close to centres of consumption; they must be located where the natural resources are to be found. One very good example of this is offshore wind power plants.The current transmission system is laid out in a traditional manner, which is based on the idea of not transporting power over longer distances as the power plants have been located near centres of consumption. It has merely played the role of interconnecting these generation/load centres, ensuring fair reliability and redundancy of supply.Nowadays, the power transmission system must be able to handle the various sources of renewable generation in a flexible electricity market. This has the consequence that the original layout of the transmission system must be re‐thought in order to accommodate the transmission needs for the future. New lines have to be constructed.Transmission lines are usually laid out as overhead lines, which are large structures, i.e. a 400 kV power pylon is 50 meters high. According to public opinion, such power lines are undesirable. Therefore, we must come up with an alternative, acceptable to the public.Underground cables fulfil the above mentioned need to be more publically acceptable, but, for long transmission lines, they are in many ways unproven. Guidelines for their design are needed.This thesis presents the results of a decade of underground cable research studies performed in Denmark by Danish TSO Energinet.dk and the Department of Energy Technology.The thesis is based upon a number of selected publications and summarises the results of these at a presentation level intended to have an easier, possibly less scientific touch. The results are taken from their scientific embedding in the papers and made more easily accessible to readers of the thesis. The full theoretical background is to be found in the papers and their references.Firstly, an introduction to the challenges when using underground cables is given, and secondly, the modelling approach and validation of this is discussed. Thirdly, making up the main core of the work presented, dynamics of underground cable systems are discussed and important cases to study are highlighted, and next, protection and fault location are discussed. The thesis ends with conclusions and future works, a bibliography and the publications upon which it is based.It is concluded that underground cable systems are technically possible for power transmission, although the maturity of the consequences of the newly made design guidelines are still in its youth. Many interesting research topics are still open, especially with regards to asset management tools.

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PB - Department of Energy Technology, Aalborg University

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Bak CL. EHV/HV Underground Cable Systems for Power Transmission. Department of Energy Technology, Aalborg University, 2015. 472 s.