Frankfurt (Germany), 6-9 June 2011

MMininiimum short circuit power in the LV mum short circuit power in the LV distribution network to meet EN 50160 distribution network to meet EN 50160 standard requirements standard requirements

David MEZERA david.mezera@eon.cz

Martin KAŠPÍREK martin.kaspirek@eon.cz

E.ON Czech Republic – Czech Republic

Frankfurt (Germany), 6-9 June 2011

This investigation was done on the basis of: 8 years experience of PQ measurement Evaluated over 3000 measurements PQ in the LV network The LV network contains of

18.005 MV/LV distribution substation [piece] 21.660 LV cable underground line [km] 17.151 LV overhead line [km]

Real LV network was monitored for a long time on 3.000 different PCC

The sources of this survey

Frankfurt (Germany), 6-9 June 2011

The final result of 3.000 measurements PQ

Frankfurt (Germany), 6-9 June 2011

Who is responsible?

DNO Pure network=low short circuit power (Sk)? Badly connected customers?

Customers Using of nonstandard apparatus? Electric apparatus?

Frankfurt (Germany), 6-9 June 2011

Minimum short circuit power LV

Thanks to IEC 725 we can set the reference impedance value, or more precisely, a relative short circuit power value for the LV distribution network and electric equipment of nominal current less than 16/75 A

Electric equipment with nominal current

Reference short circuit impedance

[Ω]

Reference short circuit power [kVA]

up to 16A 0,28 570

up to 75A 0,21 760

Frankfurt (Germany), 6-9 June 2011

Relation: short circuit power X PQ

Frankfurt (Germany), 6-9 June 2011

Relation: short circuit power X PQ

Frankfurt (Germany), 6-9 June 2011

Relation: short circuit power X PQ

Frankfurt (Germany), 6-9 June 2011

Relation: short circuit power X PQ

Frankfurt (Germany), 6-9 June 2011

Conclusions for DNO

To connect the new appliances according to Sk in the LV network

To increase Sk above minimum Sk 760 kVA, (900 kVA is recommended for today real used electric appliances) To increase the cross-section of existing LV overhead lines To build new MV/LV substations

Frankfurt (Germany), 6-9 June 2011

To increase the cross-section of the existing LV overhead lines

To increase the cross-section of the existing LV overhead lines not realizable

Frankfurt (Germany), 6-9 June 2011

To build new MV/LV substations

The final calculation is: 54% new substations. This accounts for a construction of

9723 new substations, including transformers and MV connection with approximate total investment cost of:

EUR 280 million.

Frankfurt (Germany), 6-9 June 2011

Conclusion

The pure PQ in LV network is caused by poor conditions on both sides, DNO and customer. Solution on the side of DNO is calculated on 280

million EUR. Solution on the side of customers ??