Control of superheater for electrical steam boiler for Esbjerg power plant
Author
Rasmussen, Rasmus Holmgaard
Term
7. term
Education
Publication year
2009
Pages
34
Abstract
Dette projekt omhandler modellering og regulering af en elektrisk superheater på DONG Energy’s kraftværk i Esbjerg. Ud fra en dynamisk model af superheateren udvikles en regulator, der skal holde dampens udløbstemperatur på ca. 230°C under varierende massestrøm. Projektet indledes med en analyse af kedelanlæggets reguleringssløjfer, hvorefter fokus afgrænses til superheateren, som er mindst afhængig af de øvrige sløjfer. Systemet beskrives med antagelser om ideel trykregulering via ventilen før superheateren (omkring 20 bar i kedlen og 11,5 bar i dampstrengen), mættet damp før ventilen, negligerede varmetab og en måleforsinkelse, fordi temperaturføleren er placeret efter superheateren. Modeller for ind- og udgående massestrøm og temperaturændring opstilles, parametre identificeres, og styring implementeres i Simulink. Den opnåede model og regulator testes i simulering og sammenholdes med måledata fra det fysiske anlæg. Af tidsmæssige grunde er dele af modellen ikke lineariseret, men fremgangsmåden til linearisation demonstreres. Uddraget rapporterer metode og verifikation, men indeholder ikke detaljerede testresultater.
This project models and controls an electrical superheater at DONG Energy’s Esbjerg power plant. Starting from a dynamic model of the superheater, a controller is designed to maintain a steam outlet temperature of about 230°C under varying mass flow. The work begins with an overview of the boiler’s control loops, then narrows to the superheater because it is least dependent on the others. The system description states assumptions of ideal pressure regulation via the upstream valve (around 20 bar in the boiler and 11.5 bar in the steam line), saturated steam before the valve, negligible heat losses, and a measurement delay due to the temperature sensor being located downstream. Models for inlet and outlet mass flow and temperature change are derived, parameters are identified, and the controller is implemented in Simulink. The resulting model and controller are tested in simulation and compared with measurements from the physical plant. Due to time constraints, parts of the model were not linearized, but the linearization procedure is outlined. The excerpt describes methods and verification steps but does not provide detailed test outcomes.
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