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Frankfurt (Germany), 6-9 June 2011
W. Niederhuemer – Austria – RIF Session 4 – Paper 1100
PROBABILISTIC PLANNING FOR A HIGHER INTEGRATION OF
WIND TURBINES TO MV DISTRIBUTION NETWORKS
Walter Niederhuemer
Karl Derler
Linz Strom Netz GmbH
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Frankfurt (Germany), 6-9 June 2011
W. Niederhuemer – Austria – RIF Session 4 – Paper 1100
Introduction
Feed in by onshore wind turbines into MV-grids is a particular challenge for the DSO Requests for connections primarily for several wind turbines or
small wind farms Power range of a few MW Connections distributed across the same part of the MV-
distribution network
To enable the feed in and guarantee the power quality Reduction of the installed feed in power is necessary Extending the distribution network
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Frankfurt (Germany), 6-9 June 2011
W. Niederhuemer – Austria – RIF Session 4 – Paper 1100
Introduction
Producer and DSO with different optimum Producer
Deliver full feed in power at any time Increase the energy output and thus to optimize the return Low direct grid connection costs
DSO Keep the network cost as low as possible
To support the objectives of the EU and to enable more feeding in, it is necessary To find an overall economic optimum To find a compromise between network investments and
produces energy quantity
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Frankfurt (Germany), 6-9 June 2011
W. Niederhuemer – Austria – RIF Session 4 – Paper 1100
Method of calculation Probabilistic calculation Taking into account the
statistical behavior of Output voltage in the substation Current in the branch Feed in power of the wind turbine
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Frankfurt (Germany), 6-9 June 2011
W. Niederhuemer – Austria – RIF Session 4 – Paper 1100
Result of the conventional assessment
Reduction of installed feed in power to 2,2 MW is necessary Alternatively, 0,5Mio€ investment to the grid for a 3km long MV cable
Selected network 1,2MW wind turbine +
250kW biogas plant connected
New 2MW wind turbine is planned
Connection via 17,5km overhead line 95mm² Aldrey
Conventional assessment Peak load with and
without feeding Off-peak load with and
without feeding
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Frankfurt (Germany), 6-9 June 2011
W. Niederhuemer – Austria – RIF Session 4 – Paper 1100
Result of the probabilistic calculation
Installed wind turbine power 3,2MW
Voltage exceeds the voltage limit only for a few hours.
Theoretically generated annual amount of energy about 3.000 MWh
With active power control 0,03% not feed in energy Reduction of active power
up to max. 1370kW
Cumulated relative frequency distributionvoltage at PCC
26,1
8 26,4
1
26,9
0
25,9
6
27,4
5
25,0
25,5
26,0
26,5
27,0
27,5
28,0
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Cumulated relative frequency
Vo
ltag
e [k
V]
Maximum acceptable voltage in the MV-network
feed in power at PCC: 3,2 MW wind turbine
Annual revenue loss is less than 100€ (with feed-in tariff of 9,6ct/kWh)
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Frankfurt (Germany), 6-9 June 2011
W. Niederhuemer – Austria – RIF Session 4 – Paper 1100
Result of the probabilistic calculation
Theoretically generated annual amount of energy about 7.000 MWh
With active power control 5% not feed in energy Real feed in energy
6.650 MWh Reduction of active power
up to max. 3,8MW (50% of installed feed in power)
2 times higher energy yield without additional grid investments
If a not feed in energy amount of 5% is acceptable for producers 7,5MW wind turbine power could be installed at the PCC
Yearly earning of energy of on-shore wind turbines and loss because of control or switch off if voltage level is too high
2.000
3.000
4.000
5.000
6.000
7.000
8.000
3000 4000 5000 6000 7000 8000 9000
installed wind generation power [kW]
fee
d i
n e
ne
rgy
[M
Wh
]
theoreticaly feed in energy [kWh] real feed in energy [kWh] (active power control)real feed in energy [kWh] (switch off)
~5% of not feed in energy
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Frankfurt (Germany), 6-9 June 2011
W. Niederhuemer – Austria – RIF Session 4 – Paper 1100
Conclusion
Probabilistic planning allows a better simulation of real network conditions
More than 2 times higher generation capacity by minimal network costs
Acceptance by producers of a certain amount of not feed in energy is necessary
Need of construction cost contribution for future grid investments
Need of suitable legal frameworks
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