romanens – ch – s3 – 0220
DESCRIPTION
Impact of Distributed Generation on Grid Protection. Paper n° 0220. BKW FMB Energie AG Switzerland. Florian Romanens. Romanens – CH – S3 – 0220. Content. Introduction BKW FMB Energie AG and its grid Changes in existing distribution grids Some requirements considered by BKW - PowerPoint PPT PresentationTRANSCRIPT
Frankfurt (Germany), 6-9 June 2011
Romanens – CH – S3 – 0220
Impact of Distributed Generation on Grid Protection
BKW FMB Energie AGSwitzerland Florian Romanens
Paper n° 0220
Frankfurt (Germany), 6-9 June 2011
Content
Introduction BKW FMB Energie AG and its grid Changes in existing distribution grids
Some requirements considered by BKW
Protection concept Short-circuits and earth-faults Frequency
Conclusion
Frankfurt (Germany), 6-9 June 2011
Introduction BKW FMB Energie AG and its grid
Swiss utility company based in Bern
Generation, transport and distribution of electricity
Grid: Transmission grid: 380kV, 220kV Over-regional distribution grid: 132kV, 50kV
Regional distribution grid: 16kV, 0.4kV
Interconnected
topology
radial topology
Frankfurt (Germany), 6-9 June 2011
Introduction Changes in existing distribution grids
Existing distribution grids are often built only for load flow DG can create a change in the power flow
DG
HV HV
MV MV
DG DG DG
DG
Standard distribution grid
Distribution grid with DG
by BKW:- 16kV- star point isolated
Frankfurt (Germany), 6-9 June 2011
Some requirements considered by BKW DG-protection systems have to recognize:
earth-f. and short-c. in case of fault on the DG-side quickly trip the DG-circuit breaker
earth-f. and short-c. in case of fault in the grid normally allow sufficient time for the grid to clear the fault. If the fault is
not cleared after a certain time, trip the DG-circuit breaker
over / under frequency and over / under voltage have to stay connected if f>47.5Hz and U>80%
Normally, a communication between substation and DG is used to realize an “intertrip” from the protection of the bay (in the
substation) to the DG-circuit breaker
Frankfurt (Germany), 6-9 June 2011
Short-circuits and earth-faults Protection zones
Each zone is defined by the CBs and CTs (beginning / end)
Paper n°0220 shows the protection concept for each zone
DG
Substation
DG16kV
0.4kV
0.4kV
50kV
load
16kV switchgearLine between substation and DG
Other parts of the grid
DG-zone
Frankfurt (Germany), 6-9 June 2011
Short-circuits and earth-faults Example: fault in the 16kV GIS in the substation
GIS have a rated arcing duration of 1.0s Faults in the GIS have to be cleared within 1.0s
Ipu
t
1/X
"
Iss
40msExample of WT short-
circuit behaviour
GIS
G
Relay
On the BB: cleared by the reverse interlocking busbar prot. with special “BB-intertrip”
Between CB and cable termination, the “intertrip” to the circuit breaker of the DG is used
inte
rtri
p
Simple over current functions are not appropriated
Frankfurt (Germany), 6-9 June 2011
Frequency Example with the frequency
DG have to stay connected if f>47.5Hz & U>80% Important for the stability of the grid in case of a large
disturbance
Under Frequency Load Shedding (UFLS) 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 load
Frankfurt (Germany), 6-9 June 2011
Conclusion DG are / will be connected to the distribution grid
Due to DG, the power flow-direction can change
Grid configuration has to take DG into account
Especially protection concept have to be adapted for DG
The sum of a lot of small generation units can impact on the stability and reliability of the grid
Some requirements mentioned are difficult to fulfill. Therefore, the collaboration among the partners involved in projects with DG is very important
Frankfurt (Germany), 6-9 June 2011
Thank you for you attention!