The vast majority of natural gas powered CHP units in Germany are operated heat-led and parallel to the mains. This means that if the electricity demand on site is higher than the CHP scheme’s capacity power is drawn from the mains and fed into the mains when the onsite demand is lower.
In the ice cream plant Kolibri in Nizhny Novgorod, roughly 400 km east of Moscow, things are different: There a SOKRATHERM cogeneration plant a total electrical power capacity of 1,2 MW always operates in island mode. This means that it supplies the power demand of a section of the plant fully independently without exchanging power with the mains. Three GG 402 compact CHP units are directed by the superordinate control MaxiManager which aligns their power output exactly to the electricity demand of the plant section at that time.
The implementation is shown by the power production graph of a typical workday morning (see below):
09:00: CHP units 2 (green) and 3 (yellow) run with ca. 230-320 kW each to cover the current power demand (red, 470-630 kW). In this power range two GG 402 units provide enough power reserve to balance short-term demand fluctuations.
09:52: The power demand rises substantially from 460 kW to 863 kW within eight minutes (10:00). Because of this demand jump both running CHP units increase their power produciton to nearly 400 kW and CHP unit 1 (blue) is started. Within less than two minutes its power production increases from 0 to 338 kW.
10:04: The power demand decreases to 656 kW. The power of CHP unit 1 is reduced to 216 kW, CHP units 2 and 3 are aligned. In the following hours all three CHP units run at roughly the same power beween 210 and 310 kW to cover the increased power demand.
Further information can be found (in German) in the BHKW des Monats September 2016 project report of the Energie & Management professional newspaper.