Consult regarding the sequence for putting \"vessel three-inertia control\" and \"heating furnace cascade control\" into automatic mode
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1. The drum level is controlled using a \"three-element feedback system\", which consists of \"water inflow rate\", \"steam output\", and \"level\". The liquid level is the primary parameter, while it is a secondary parameter during water intake. So when switching to automatic mode, should the primary parameter be set first or the secondary parameter? 2. For the cascade control of the heating furnace, when switching to automatic mode, should the \"internal setpoint\" be set first or the \"external setpoint\"? Please give some advice from experts!
When putting a cascade control system into operation, it is generally done in the order of the secondary system first and then the primary system, and it is necessary to ensure a disturbance-free switchover (this point mainly applies to older electric Type II instrument systems)
In terms of drum three-parameter control, it is generally a single-stage control, that is, one controller is used, and there is no issue regarding the selection of primary and secondary parameters； If cascade control is used, it is similar to the cascade control in a heating furnace: the inner loop setpoint is used first, and once the situation becomes more stable, the outer loop is activated.
Three-input systems are generally feedforward-feedback or feedforward cascade control systems; the liquid level should be controlled directly via water flow, while steam flow is used to prevent \"false liquid levels\". Therefore, the primary parameters should be set first, and only after the system reaches equilibrium should the secondary parameters be adjusted.
Regarding what was mentioned upstairs about the three impulses of the steam drum, are there primary and secondary parameters?