Public Service Company of New Mexico (PNM) has a 345 kV series-compensated transmission line that was bisected by a new substation. The location of this substation resulted in one of the new line segments being overcompensated by 170 percent. Because of this, the line protection scheme applied by PNM included both phasor-based and ultra-high-speed (UHS) protection using incremental- and traveling-wave-based principles. This marked the first time that a relay based on traveling-wave protection principles was applied to protect a high-voltage transmission line with the trip circuits live to the breakers. This event was made possible with the use of the new Traveling Wave Relay Testing (TWRT™) capability in the Real Time Digital Simulator (RTDS®).
Jordan Bell, Schweitzer Engineering Labs