Unit Force Derating Level #1

Derating meaning if a unit of power plant can't supply electrical as load demand more than 2% from dispatch. For example if a unit demand of power plant are 660MW and somehow got one of five pulverize get trip and the unit get runback to 500MW it call unit derating status level 1 160MW(FD#1 660-500=160MW) but if it less than 30 min can recovery back to 660MW, the status of FD#1 is cancelled.

Derating status can be release if unit of power plant can recovery as dispatcher demand. For example if a unit of power plant as above after fix the trouble should be inform to dispatcher soon. If the dispatcher order to keep the load demand, at that right time the derating status is release but if dispatcher order to increase the load until 660MW, the derating status will release until unit load reach 660MW as animation below (FD#1 for 40min).

Derating level #1 (FD1) is the lowest categorize and frequently happen and following with unit runback. If the operator can detect abnormal condition early, we can avoid status FD1 as below.

PD Plant Derating is scheduled derating last month before.
MD Maintenance Dearating is scheduled derating last week before Thursday.
FD1....
FD2 Force Derating level #2 is unscheduled derating but can be wait until 6 hours letter.
FD3 Force Derating level #3 is unscheduled derating but can be wait more than 6 hours.

Runback
Every unit runback of course created derating status. Runback can be categorize four kind.
1. 75% runback.
If get get one of five pulverize trip.

2. 50% runback.
If we get one of two Induce Drive Fan trip.
If we get one of two Force Drive Fan trip.
If we get one of two Primary Air Fan trip.
If we get one of two Air Heater trip.
If we get one of two Boiler Feed Pump trip.
If we get one of two Circulating Water Pump trip.

The key of these are operators must give information to dispatcher as soon as possible if we have the progress of the unit status.