Grid Inertial Response with Lithium-ion Battery Energy Storage Systems
Authors
Knap, Václav ; Sinha, Rakesh
Term
4. term
Education
Publication year
2013
Submitted on
2013-06-03
Abstract
Denne afhandling undersøger, hvordan store lithium-ion-baserede energilagringssystemer (ESS) kan hjælpe elnettet med at håndtere inertirelaterede udfordringer. Netinerti er den træghed, der gør, at netfrekvensen ikke ændrer sig for hurtigt ved pludselige ubalancer mellem produktion og forbrug. Her foreslås ESS som en løsning, fordi batterier kan levere og optage effekt meget hurtigt og dermed yde en form for “inertial respons”. Arbejdet omfatter udvikling af en model af et batteri-energilagringssystem i MATLAB/Simulink samt en model af en vindmølle-generator med fuldskala-konverter og en konverter til ESS i RSCAD. En 12-bus netmodel er implementeret for at undersøge den dynamiske inertialrespons ved forskellige niveauer af vindkraft i nettet. Der er gennemført realtidssimuleringer af henholdsvis elsystemet og ESS med RTDS og dSPACE. Der er analyseret forskellige metoder, hvorved ESS kan levere inertialrespons: dels regulering, der reagerer på hastigheden af frekvensændringer (derivativ regulering), dels en kombination af derivativ- og droop-regulering, hvor droop knytter effektlevering til selve frekvensafvigelsen. Desuden er effekten af ESS-størrelse på inertialresponsen vurderet, og konsekvensen af vindkraftens variabilitet for systemfrekvensen er simuleret. Resultaterne præsenteres gennem flere casestudier.
This thesis examines how large lithium‑ion battery energy storage systems (ESS) can help the power grid address challenges related to inertia. Grid inertia is the property that prevents the system frequency from changing too quickly when there is a sudden imbalance between supply and demand. ESS are proposed as a solution because batteries can inject or absorb power very rapidly to provide an “inertial response.” The work includes developing a battery ESS model in MATLAB/Simulink and models of a wind turbine generator with a full‑scale converter and an ESS converter in RSCAD. A 12‑bus grid model is implemented to study the dynamics of inertial response at different levels of wind power in the system. Real‑time simulations of the power system and the ESS are performed using RTDS and dSPACE, respectively. The study evaluates several ways for ESS to deliver inertial response: a controller that reacts to the rate of change of frequency (derivative control) and a combined derivative–droop approach, where droop links power output to the frequency deviation. It also analyzes how ESS size affects the response and simulates how wind power variability influences system frequency. The results are presented through multiple case studies.
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