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On Load Tap Changer (OLTC) Regulating Transformer Using Variable-Ratio Transformer Blocks

This example illustrates the use of an On Load Tap Changer Transformer (OLTC) to regulate positive-sequence voltage at a 25-kV bus in a transmission network.

Description

This example illustrates the use of an On Load Tap Changer Transformer (OLTC) to regulate positive-sequence voltage at a 25-kV bus in a transmission network. During the simulation we can observe OLTC reaction for a 1.1 pu over-voltage in 120 kV network, a 0.95 pu under-voltage in 120 kV network, and a 0.2 sec single-phase fault at the 25 KV bus.

Simulation

Reference voltage is set at 1.0 pu. Observe OLTC reaction for the following 3 events: * 1.1 pu over-voltage in 120 kV network at t = 2 sec. * 0.95 pu under-voltage in 120 kV network at t = 10 sec. * 0.2 sec single-phase fault at B2 bus at t = 20 sec. OLTC does not react because under-voltage duration is lower than the specified Delay (0.4 sec).