Integration of 50 % wind power in a CHP-based ... - Ea Energianalyse

ea.energianalyse.dk

Integration of 50 % wind power in a CHP-based ... - Ea Energianalyse

130 Economic Analysescating that heat is more needed than electricity. As a consequence, there is no demandfor production from condensing units.Looking at the production in May in 2008, there seems to be a relatively large amount ofproduction hours lying in-between the constraints. Still however, a great amount of theproduction seems constrained by partly the lower part of the backpressure line as well asby the minimum power generation, indicating a small heat demand. As the wind capacityincreases towards the 2025 wind scenario the trend of CHP production being constrainedby the backpressure and minimum electricity generation limits, increases.Regarding the production in September 2008, the pattern looks similar to the one inMay, except that in September we see a great amount of production from condensingunits, which indicates periods with higher electricity- than heat demand. In this connection,it is worth mentioning that the condensing units are modeled with a slightly higherelectrical net efficiency (50 %) than extraction units, when extraction units operate incondensing mode (45 %). This explains why the extraction units never generate condensingelectricity. When the wind capacity increases, the amount of condensing electricity isgradually reduced, and the production from extraction units is more “pressed” down towardsthe backpressure- and electrical minimum constraints. This indicates an increasedneed for producing more heat while maintaining (or reducing) power generationas well as to generate lesser power than allowed by the technical minimum of the boiler,respectively (if the opposite was the case, with more power being needed, this could easilybe generated by ‘moving’ the production point away from the backpressure line).The production diagram of the bypass system (full-scale) is seen in Figure 7.4 below,comparing the production in January, April and November, all subjected to the windyprofile. As is the reference system, we see that January is characterized by all extractionunits operating in bypass mode constantly (with the exception of a few hours), whereasthe production in April and November to a greater extent is co-generated. It is the presumptionthat a share of these hours of backpressure operation rather would be in BPOmode if the lower capacity-limit had been lowered.Full‐scale bypass scenario, Windy profileJanuary April NovemberEl. El. El.Bypassed heatLower heat productionproductionlimit of bypass modeHeat Heat HeatFigure 7.4, Comparison of the central production history in relation the upper and lowerconstraints (heat-electricity diagram), optimized for the full-scale bypass scenario forJanuary, May and October, all subjected to the windy profile.

More magazines by this user
Similar magazines