Battery system Sizing
Battery system Sizing
(OP)
Guys,
I am sizing battery systems for an LNG plant. We are in the preliminary stage and we have not bought LV and MV breakers.
I am taking the conservative approach of considering 1 trip coil + 1 close coil for all LV and MV breakers shown in overall One line diagram.
Do you think this is a reasonable design or I am over-sizing the battery system?!
I am sizing battery systems for an LNG plant. We are in the preliminary stage and we have not bought LV and MV breakers.
I am taking the conservative approach of considering 1 trip coil + 1 close coil for all LV and MV breakers shown in overall One line diagram.
Do you think this is a reasonable design or I am over-sizing the battery system?!






RE: Battery system Sizing
Once you've cleared that worst case fault, a bus fault somewhere, you still have all the continuous DC loads and may still need to clear more further up stream. Eventually you'll need to be able to close something to get AC station service restored to the chargers. I see no reason to need to close everything on the battery without the chargers. Also, keep in mind that trips can be simultaneous, but closes will almost always be sequential.
RE: Battery system Sizing
Depending on what your client wants, we are asked to consider worst fault scenario during 1 minute. Usually a main TX or Gen fault. which includes breakers and air breaks to isolate the fault/bus.
Then for 478 minutes we are asked to consider steady load. These are the indicators that DavidBeach refers to, relays, SCADA etc.
then on the last minute we are asked to consider restoring the breaker (with the biggest closing current and motor starting current) at a time.
Again, these would change depending on your client. I remember one time we ha a fault during the weekend and we couldnt get a crew until monday. We had to have a guy run a gas generator to keep the system going. Poor guy spent the night in his truck. hahah
RE: Battery system Sizing
RE: Battery system Sizing
Also, IEEE 485 has good advice.
RE: Battery system Sizing
(Over time, all batteries lose capacity to deliver power, so you need to assume some loss factor (or some lifetime percent of use) that reduces your "initial purchase" capacity. )