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

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

40 The impacts of wind power on price formation and production patterns4.4.2. DurationsFigure 4.14 below shows a two-day sample taken from the end of 2007 in which a coupleof periods with low prices of various lengths occur.3000,0A Two‐day sample with periods of low pricesPower [MWh/h]2500,02000,01500,01000,0500,00,0400350300250200150100500Price [€/MWh]centraldecentralizedLow‐priceperiodWind‐residualel. demandPriceTime [h]Figure 4.14, The graph displaying thermal production, the spot price as well as the wind-residualel. demand shows that it is hard to see, if the thermal production responds to the falling prices atall. (data source: Energinet.dk).In the sample shown above it looks as if the thermal production does not really react tothe critical prices – nor when the wind-residual demand is less than zero – in the waythey ideally should; by reducing el. generation. The occurring reduction might as well bean effect from fallowing the normal profile of demand for co-generated district heating.Or to put in another way: the el. generation is most likely constraint by something elsethan the electricity price. However, the exact amount of latent el. generation remainsmore or less hidden within the numbers.Because central power units – opposed to smaller gas fueled decentralized units – arenot capable of responding quickly to load fluctuations, the duration of low price periodsbecomes important when discussing the lack of down regulation. In this connection, aduration curve showing all durations of low-price hours registered from the five yearobservation period is to be found in Figure 4.15 (below, left). Figure 4.16 shows the samehours distributed by month. It also shows the amount of periods lasting longer thanthree hours – in this way ignoring the shorter low-price periods. The short low-price periodsmake up 64 % of the total 249 periods, and the remaining 89 periods last morethan three hours. However, these 89 periods correspond to 67 % of the total amount oflow-price hours – a statistical information that can be useful in terms of a possible downregulationof the electricity generation on central units, when being concerned abouttheir thermal dynamic properties.

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