Help me visualize...
Pelton? Francis? Kaplan? Deriaz?
If any of the last three, is the standing tailrace elevation such that when the wicket gates are closed to 0% pinch [and, in the case of a Deriaz unit, the blades are moved to minimum pitch] the draft tube vents will rapidly vent the runner so it rotates in air, or will tailrace suppression using compressed air be harnessed? I ask because detection of pressures and levels associated with these constraints can be, but are not always, employed as what are essentially interlocks to keep the operation of the the unit within its design envelope...
Generally expanding on that, I'd be looking to see that adequate controls are in place to ensure compliance with the unit's capability curve, not only of the alternator itself but also of the turbine and its mechanical limitations, such as which gate openings can/will cause cavitation, vibration, etc.; narrowing one's focus too exclusively can be detrimental to the equipment, not to mention to one's career...
Just for starters, off the top of my head, I'd be looking for the following, with design, validation of design, confirmation of correct construction/wiring/connection, and commissioning verification of correct function:
- controls on minimum excitation so as to prevent pole-slip / out-of-step operation, and protection schemes to trip unit off line if controls fail
- limited time and continuous rating overvoltage limits controls and trips
- "transient stability excitation control" / "field forcing" / "disturbance ride-through capability" are various names for approaches to the use of a synchronous machine to both stabilize system voltage during faults and ensure it remains stably connected to the system post-event
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
