Voltage Regulation & Sensing - Prime Power Generators

[FreddyNurk]

Folks,

My current employment consists of looking at isolated grid prime power stations, normally powered by diesel generators of sizes ranging from 50kW up to about 1.5MW, with various configurations onsite.

We normally use Basler SR4 AVRs for our larger stations, with a few Stamford units in certain locations. The policy here (which had been set long before I arrived) was to only use single phase sensing, (i.e. Stamford MX341) which gives a certain voltage regulation capability.

In previous employment we always specified the 3 phase sensing units, along with control of the voltage / VAr sharing via load panels. Currently we use cross current compensation, with no control of voltage / VAr sharing carried out by the generator automatics.

Clearly there is more than one way to achieve something, and thus I'm curious as to what benefits there are in better voltage regulation in such systems, as clearly some of my prior clients wanted the 3 phase sensing, whereas currently it doesn't appear to be as important.

Does anyone have reasons as to why such tighter voltage regulation would be important?

 

[catserveng]

Connected load dynamics and power quality, UPS systems, DC drives, and many lighting systems have harmonics that can cause problems for single phase sensing AVR's.

Newer AVR's have better protecttion capabilites, and ability to communicate faults to a supervisory system if desired.

Cross current compensation can work well in certain situations, but in mixed plants, or sites with certain transient conditions active VAR/PF control may provide better response and stability.

Better customer metering/monitoring can identify poor regualtion where in the past older analog meters with low resolution may have not indicated any problems. Funny how when some generator panel came out with digital metering how much the number of complaints went up for "instability" or "poor regulation".

My 2 cents worth.

Mike L.

 

[FreddyNurk]

Your comments make sense, my prior employer installed generators in weak grids, in conjunction with large (at least compared to the size of the generator) inverters and with likelyhood of large step loads (they did renewable integration) whereas my current employer seems to have far less transients in their networks, and no large inverters either.

I have a suspicion that every time they go to site to service the generators they reset the voltage on each set again too.

Thanks for the comments.