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Customer Success Story

Kanawha River

The controllable series capacitor at Kanawha River

In 1991 a segmented series capacitor was installed by Hitachi Energy in the south-eastern part of the American Electric Power Service Corporation (AEP) system. This grid includes lines at 765 kV, 345 kV and 138 kV. There series capacitor was installed in the Kanawha River – Funk 345 kV line, which is 174 km long.

An installation that provides flexibility
Before the installation of the series capacitor, the loadability of this line was limited to about 950 MW. Series compensation to a maximum degree of 60 % was required, as contingency loading resulting from the outage of a critical 765 kV circuit could exceed this limit.

Fixed series compensation of 60 % would have increased system losses unnecessarily under normal operational conditions. However, segmented capacitors, in 10 % increments over the range 0% to 60%, could be justified since this provides flexibility to use only the minimum amount of compensation required to meet current system conditions. 

Main data
System  FSC
Commissioning year  1991
System voltage 
 345 kV
Rated reactive power  788 Mvar
Degree of compensation  60 % in 10 % steps 
MOV rating  39 MJ
Protective level 2.25 pu