Hierarchical Control of an AC Microgrid
Author
Airi, Roberto
Term
4. term
Education
Publication year
2018
Abstract
Denne afhandling adresserer de udfordringer, som stigende udbredelse af vedvarende energikilder og distribuerede ressourcer skaber i elnettet, herunder variabel produktion, tovejs effektflow og krav til netkvalitet. Som en omkostningseffektiv løsning beskrives mikronettet, hvor slutbrugeren bliver ”prosumer”, og kraft-elektroniske konvertere og lagersystemer muliggør lokal forsyningssikkerhed og reducerede tab. Afhandlingen undersøger og implementerer hierarkisk styring af et AC-mikronet. Primær styring omfatter indre strøm- og spændingsløkker, droop-baseret effektdeling og synkronisering, mens sekundær styring genopretter frekvens og spænding via både centraliserede og decentraliserede tilgange, inklusive styring af reaktiv effekt. Mikronettets drift i ø- og nettilsluttet tilstand gennemgås med fokus på stabilitet, power quality ved fælles koblingspunkt og samspillet mellem kontrolniveauer, herunder problemstillinger ved parallelkobling af spændingskildeomformere. Resultater og detaljerede konklusioner er ikke indeholdt i det medtagne uddrag.
This thesis addresses challenges introduced by the growing deployment of renewable energy and distributed resources in the power system, including variable generation, bidirectional power flows, and power quality requirements. As a cost-effective solution, the microgrid is presented, enabling the end user to act as a prosumer while power electronic converters and storage systems support local reliability and reduced losses. The thesis studies and implements hierarchical control of an AC microgrid. Primary control covers inner current and voltage loops, droop-based power sharing, and synchronization, while secondary control restores frequency and voltage using both centralized and decentralized approaches, including reactive power flow control. Microgrid operation in islanded and grid-connected modes is examined with emphasis on stability, power quality at the point of common coupling, and interactions between control layers, including issues in paralleling voltage source inverters. Specific results and conclusions are not provided in the excerpt.
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