Island Falls to Points North transmission system planning studies

The author describes the planning studies conducted in the development of a transmission line proposal to supply power to several remote mines located in northern Saskatchewan. Because the required length of transmission line will be extensive, with large induction motor loads concentrated near the line end, the potential exists for extremes in voltage, both in steady state and during contingencies. The studies discussed principally address these possible voltage control problems. A 138 kV, uncompensated Island-Falls-to-Points-North (IF-PN) transmission line, with 477 kcmil conductor, was recommended for this system. The steady-state studies conducted show that series or shunt compensation would be necessary to supply the peak system load condition for 115 kV operation. Avoiding the need for series compensation on the 138 kV system will allow more capacity for upgrading the system in the future. Even though an additional transformation would be required for 138 kV operation, the reduced losses associated with 138 kV operation would represent a cost advantage compared with a 115 kV compensated system. Dynamic simulation studies confirmed that a 138 kV uncompensated IF-PN transmission system would satisfy the requirements for fault recovery, motor starting, and overvoltage control