Real-Time Automation Control of a Phase-Shifting Transformer Based on Mission Priorities

The Silicon Valley Power (SVP) system is connected to the area transmission system via one 230 kV interconnection and five 115 kV interconnections. To reduce the active power import from the 115 kV interconnections and increase the active power import from the 230 kV interconnection (and therefore reduce the cost of active power import), SVP installed a 420 MVA, 230/230 kV phase-shifting transformer (PST) at Substation A. The PST operation at SVP should satisfy N-1 contingencies in that a loss of any important transmission line within the SVP network should not overload any other lines. This paper presents mission-priority-based active power control (P control) of a PST to achieve the optimal cost of the active power import and satisfy predetermined N-1 contingencies. A mission priority is an established control algorithm for different preset conditions. The proposed mission-priority control is tested in a closed-loop environment to demonstrate its effectiveness.