algorithms are used. Additionally:
4.7.7RATE ADJUSTMENT
When the Slave dropout/return compensation parameter specifies a rate adjustment and a rate compensation event occurs (a slave leaves while firing, or a slave returns) then rate adjustment will alter the integrator value so that the commanded rate compensates for the added or lost capacity.
INTEGRATOR COMPENSATION
A
Whenever an override has occurred then, at the moment the override ends, the integrator is loaded with a value that causes the PID output to match the current rate, whenever this is possible within the integrator’s limits. The Lead Lag PID will implement similar behavior: The rate allocator will provide a trigger that causes the integrator's value to be recomputed and this trigger will activate whenever a rate allocation limit is released; that is, this event will occur any time the system transitions from the condition in which it is not free to increase the total modulation rate, to the condition where this rate may increase.
4.7.8IMPLEMENTATION
The examples below are ways in which this may occur, but in implementation what is necessary, first of all, is to use a rate allocator that assigns rate to each slave and can detect when all of the assigned rate is absorbed, or if there is excess requested rate that the firing stages could not absorb.
Then:
Whenever the system is rate limited, that is, when A) all firing stages are commanded to their respective maximums and also B) the PID is asking for more heat than that, note that this has occurred by setting a flag and also record total rate that the system absorbed (the total of the commanded maximums, not the PID's requested rate which might include excess).
Whenever the rate allocator completes an execution pass and detects that both conditions
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Date: 8-4-2010
Revision: 0
Form: 2396
of step 1 are no longer true (demand has decreased) then it clears the flag.
Whenever the rate allocator completes an execution pass and detects both conditions of step 1 are true, and it also detects that the total rate potentially absorbed by the system (the commands have not yet been sent) has increased from the value that was saved when the flag was set, then it
Examples include:
•The rate allocator has encountered a limit such as base load (for a "limited" rate allocation scheme) and this limit is released.
•All stages are at their maximum (base load, or max modulation) and one or more stages are
(This is indicated by the Slave Status "slave is modulating": the changing from false to true is not, itself, a trigger, but while it is true the rate allocator can assign to the slave only the firing rate that it is reporting; thus the release of this might allow more rate to be absorbed by the system. It also might not do this, if for example the slave was in anticondensation and thus the rate limit was maximum modulation rate.)
•All firing stages are at their maximum (base load, or max modulation) and a stage which was OnLeave returns in the firing state and is available for modulation.
•An
This also applies when the system is first starting up, that is, all firing burners are at their limits (zero) because non are firing, and thus when the
Lead Lag Burner Demand