I don't know the keyboards to be definitive, but I don't think so. However, it's worth
checking the manual to see what you can discover. I've printed off some schematics for
Joystick port adaptors and none of those included power so it might have been specific to
the keyboard and cable. I've found a link to the manual here.
It only mentions a standard power supply, no mention of
power over MIDI.
I know a few MIDI pedal boards had the option for MIDI power,
but they were clearly defined as non-standard MIDI devices. Although the MIDI standard
uses a 180 degree 5 pin DIN connector, the cable is a twisted pair and screen with 2 pins
at the connector unused. And those MIDI pedals took advantage of the unused pair of
connectors to deliver power to the unit.
If you REALLY wanted a remote power
supply through the MIDI cable you could do it. But you need to make a couple of boxes, one
to input the power into the cable and another to break it out, and get some cables with
all 5 pins connected. Would make things nice and neat, but at the expense of having to
carry non-standard MIDI cables for spares.
When the going gets weird, the Weird turn Pro.