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Case Study

El Tablazo, Yaracuy

Series Compensation for fast and cost-effective increase of transmission capacity in power grid

In a contract with ENELVEN, a regional electrical utility in Venezuela, Hitachi Energy has installed a total of five series capacitors in their power grid to increase the capacity of existing overhead transmission lines serving the petroleum and petrochemicals center of Maracaibo. The total installation of reactive power in the contract amounts to close to 800 Mvar at 400 kV. It was commissioned in 2003. A sixth series capacitor is planned for a future extension of the grid in the same area.

The main purpose of the transmission corridor is to transmit low cost hydroelectric power to western Venezuela. Before, the system lacked the capability to transmit all the power needed, therefore the use of expensive fuel was required for local generation. By series compensating the three 400 kV lines between Yaracuy substation and El Tablazo substation, plus the lines between Yaracuy - Planta Centro and Yaracuy - Arenosa, the total power transmission capacity was increased from 1800 MW to 2125 MW. Three series capacitors are located at El Tablazo and two at Yaracuy.

The project is making additionally 325 MW of power available to help meet growing demand for power in the Maracaibo region, and enables ENELVEN to defer major investment in additional transmission lines or new generating capacity to a later stage.

Thus, conventional solutions to ENELVEN’s anticipated shortfall in power would have been to build additional transmission infrastructure to permit more electricity to be imported into Maracaibo, or to build new generation plants to produce power at the point of demand. But these solutions would have required more complex investments, have had considerable environmental impact and could have taken several years to receive the necessary rights of way and permits.

Instead, with series compensation, ENELVEN has gained a fast and very substantial increase in available power, at around one fifth of the cost of adding new transmission capacity.

Under the terms of the greenfield contract, Hitachi Energy designed, built, installed and commissioned five series capacitors, one for each of five existing 400 kV transmission lines. A considerable supply of line protection equipment was part of the undertaking, as well.

Main data  
System   FSC 
Commissioning year   2003
 Substation El Tablazo  Yaracuy
 Number of series capacitors  3  2
 Nominal system voltage  400 kV  400 kV
 Rated current  1185 A  1481 A
 Overload current, 30 minutes  1600 A  2000 A
 Rated power  126 Mvar  197 Mvar
 Degree of compensation  25%  50%
 Series capacitor reactance  30 Ω  30 Ω
 Type of protection  Gapped  Gapped
 ZnO rating 78 MJ  165 MJ

Plant layout, El Tablazo, Yaracuy FSC