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UFLS with dispersed generation. Round Table 3b: Smart grid protection. BKW FMB Energie AG Switzerland. Florian Romanens. Romanens – CH – RT 3b – 0220. Content. UFLS, how does it work? Generation has to stay connected Example UFLS-concept in CH UFLS with dispersed generation
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UFLS with dispersed generation Round Table 3b: Smart grid protection BKW FMB Energie AG Switzerland Florian Romanens Romanens – CH – RT 3b – 0220
Content • UFLS, how does it work? • Generation has to stay connected • Example UFLS-concept in CH • UFLS with dispersed generation • Inputs for the discussion
UFLS, how does it work? • UFLS: Under Frequency Load Shedding • Principle: • If the load is bigger than the generation, the frequency will fall. In this case, a certain amount of load has to be shed, but the production has to stay connected to support the grid.
Generation has to stay connected f=constant f=50Hz f generation load UFLS f Problem in the transmission grid
Example UFLS in Switzerland • Generation has to stay connected if f>47.5Hz & U>80% Used in CH Reference: Transmission Code of Switzerland
Measurement of the shed power UFLS-Rel.Basis UFLS-Rel. Today example in CH BB 220kV BB 380kV BB 50kV BB 132kV BB 12kV BB 16kV G G BB 400V BB 400V
UFLS with dispersed generation • Generation is decentralized • Number of dispersed generation units will increase even more • Challenge: • Only load has to be shed • Generation must not be disconnected
Example of decentralized generation with UFLS Based on CH • Frequency falls to 48.3Hz
measurement of the shed power Options ? Option A BB 220kV BB 380kV • Relay centralized in the substation • Communication to the load-feeders BB 50kV UFLS-Rel. BB 16kV G BB 400V G G G G G
measurement of the shed power Options ? Option B BB 220kV BB 380kV • Relays decentralized in the distribution grid BB 50kV UFLS-Rel. BB 16kV G UFLS-Rel. UFLS-Rel. UFLS-Rel. BB 400V G G G G G
Input for discussion • How to realize UFLS with decentralized generation?