Harmonic Mitigation of Biomass-Fired Combined Heat and Power Plant
Authors
Lorenzen, Søren Lund ; Nielsen, Alex Buus
Term
4. term
Education
Publication year
2017
Submitted on
2017-06-01
Pages
116
Abstract
Dette speciale, udført i samarbejde med Aalborg Energie Technik A/S og med udgangspunkt i biomasse-kraftvarmeværket Helius CoRDe, undersøger gevinsterne ved at installere et centralt aktivt effektfilter (APF) for at reducere harmoniske strømme fra seks-puls ensrettere og frekvensomformere. Gennem analyser, simuleringer (MATLAB/Simulink/PLECS) og laboratorieforsøg (dSPACE) sammenlignes to strømregulatorer i APF’ets indre kredsløb: en PR-regulator og en repetitiv regulator, begge under en ydre DC-spændingsregulator. Eksperimenter viste, at den repetitive regulator opnår den bedste harmoniske dæmpning med en netstrøm THD på 6,4 %, mens PR-regulatoren er mere fleksibel og har kortere indsvingningstid. Fordelene ved APF omfatter lavere strøm-THD ved PCC, reducerede tab i transformer og kabler, mulighed for reaktiv effektkompensation og dermed potentielt lavere effektdimensionering, samt en centraliseret løsning frem for lokale filtre. Enkle dimensioneringsligninger kombineret med Danfoss’ harmoniske værktøjskasse gav hurtige og pålidelige estimater, som stemte godt overens med simuleringer, og udgør dermed praktiske retningslinjer for APF-design. Ifølge simuleringer og eksperimentelt arbejde kan APF desuden muliggøre en effektbesparelse på cirka 5–9 % for mellemspændingstransformeren og tavlen.
This thesis, conducted with Aalborg Energie Technik A/S and centered on the Helius CoRDe biomass-fired CHP plant, evaluates the benefits of installing a centralized active power filter (APF) to mitigate harmonic currents produced by six-pulse rectifiers and variable-speed drives. Using analysis, simulations (MATLAB/Simulink/PLECS), and laboratory experiments (dSPACE), two inner-loop current controllers for the APF—proportional resonant (PR) and repetitive—are compared under an outer DC-link voltage controller. Experiments showed that the repetitive controller achieved the best harmonic mitigation, with a grid current THD of 6.4%, while the PR controller offered greater flexibility and faster settling. The APF delivered reduced current THD at the PCC, lower transformer and cable losses, the option for reactive power compensation and thus potentially lower equipment ratings, and a centralized alternative to per-load filtering. Simple sizing equations combined with the Danfoss harmonic toolbox provided quick and reliable estimates that matched simulations, offering practical design guidelines. Simulations and experiments further indicate potential power savings of approximately 5–9% for the medium-voltage transformer and switchboard when using an APF.
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