System analysis for improved energy recovery on Prasa’s electrical traction network

Lategan, Luca (2017-03)

Thesis (MEng)--Stellenbosch University, 2017.

Thesis

ENGLISH ABSTRACT: In the very competitive transport market, operators are constantly looking for ways to drive down operational expenses and act on social sentiment to promote their service. Energy recovery through regenerative braking provides an answer to both these issues by reducing energy expenditure and acting on the call for “greenness” by reducing the carbon-footprint of the operation. This thesis investigates the possible energy savings that can be realised through harnessing the regenerative braking capabilities of new Alstom train sets ordered by the Passenger Rail Agency of South Africa (Prasa). A dynamic load-flow analysis of the 3 kV DC and 33 kV AC electrical network of Metrorail Western Cape will be done to analyse the current capacity of, and future demand on the electrical network. The feasibility of introducing, as well as the ideal placement of, energy recovery equipment will be investigated. This will be done to maximise the potential energy savings and return on investment that can be realised through the regenerative braking capabilities of the new train sets. DIgSILENT PowerFactory, was chosen as simulation package to build a virtual model of the electrical traction network and conduct dynamic simulations. In order to validate the accuracy of the predicated future network state, with the future rolling stock, the simulation results of the existing rolling stock and electrical network were benchmarked against real measured data. Due to the good correlation between the simulation results and the measured data, the simulation results of the network with other rolling stock models should also prove to be equally accurate. The simulation model was adapted with the dynamic load model of the future train sets to simulate the projected future state of the electrical traction network. This offered insight into the predicted supply versus demand, over and under voltages as well as the effect of regenerative braking on the power flow. More ideal feeding and sectioning philosophies were also investigated. The new rolling stock’s installed power of 11;2MW is significantly higher than the 3;52MW of the current rolling stock. The simulation results of the future network state indicate that the new trains will not be able to operate at their intended performance levels. The proposed feeding and sectioning alterations will increase efficiency, but the installed capacity will have to be increased and a number of substations have been identified in this regard. To better utilise the new rolling stock’s regenerative capabilities, various options was investigated and the ideal location for the installation of energy recovery equipment was identified.

AFRIKAANSE OPSOMMING: In die hoogsmededingende vervoerindustrie is operateurs aanhoudend op soek na wyses waarmee bedryfsuitgawes verlaag kan word asook om op maatskaplike gevoelens ag te slaan om hul diens te bevorder. Energieherwinning deur middel van terugvoerremming bied ’n antwoord vir beide van hierdie kwessies aangesien dit die kragrekening verlaag én die vraag na meer omgewingsvriendelikheid sus deur die koolstofvoetspoor van die bedryf te verlaag. Hierdie tesis ondersoek die moontlike energiebesparing wat bereik kan word deur die terugvoerremfunksionaliteit van die nuwe Alstom treinstelle te benut. Dit is deur die Passasierspooragentskap van Suid-Afrika (Prasa) bestel. ’n Dinamiese energievloeianalise van Metrospoor Wes-Kaap se 3 kV GS en 33 kV WS elektriese netwerk sal aangepak word om die huidige vermoë en toekomstige belasting van die netwerk te ontleed. Die lewensvatbaarheid en ideale ligging van energieherwinningstoerusting sal ondersoek word. Dit sal gedoen word om die moontlike energiebesparing en beleggingsopbrengs, wat deur die nuwe treine se terugvoerremming moontlik gemaak word, te maksimeer. DIgSILENT se PowerFactory is gekies as die simulasiepakket om ’n nabootsing van die elektriese trekkragnetwerk mee te bou en dinamiese simulasies te doen. Om die akkuraatheid van die voorspelde toekomstige netwerktoestand, met die toekomstige rolmat, te bevestig is simulasieuitslae van die huidige rolmat en elektriese netwerk vergelyk met gemete data. Danksy die goeie korrelasie tussen die simulasieuitslag en metings behoort die data wat verkry word deur die netwerk te simuleer met ander rolmatmodelle óók redelik akkuraat te wees. Die nabootsing is aangepas met die dinamiese model van die nuwe treinstelle om die toekomstige toestand van die trekkragnet te voorspel. Dit het insig verskaf oor die voorspelde toekomsige aanbod teenoor aanvraag, oor- en onderspanning asook die invloed van terugvoerremming op die energievloei. Meer gepaste voer- en seksie-indelingstrategieë is ook ondersoek. Die nuwe rolmat se kenvermoë van 11;2MW is aansienlik hoër as die 3;52MW van die huidige vloot. Die simulasieuitslae van die toekomstige netwerktoestand dui daarop dat die nuwe treine nie teen hul beoogde werkverrigtingsvlak sal kan loop nie. Die voorgestelde voer- en seksie-indeling-aanpassings sal die doeltreffendheid verhoog, maar die geïnstalleerde netkapasiteit sal verhoog móét word. ’n Aantal voorstelle is in hierdie verband gemaak. Om die nuwe rolmat se terugvoerremmingsvermoë beter te benut is ’n substasie geïdentifiseer waar energieherwinningstoerusting moontlik geïnstalleer kan word.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/100935
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