Seeking advice on the commissioning of complex control systems
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I would like to ask everyone: in low-selectivity control for compressor management, which specific low value should be chosen? Also, how should one get started with setting the PID parameters for a simple cascade system?
“It’s kind of like a tongue-twister: “Which low selection should be chosen in the low-selectivity control of the compressor?” Typical automatic control systems operate when the production process is under normal conditions; in the event of abnormal conditions, automatic control is usually switched off and manual operation is adopted, with automatic control being reactivated once the conditions have largely returned to normal. Determine whether the operating conditions are normal, and make a choice between the two control systems. This is known as a selective control system, also referred to as replacement control or override control. “\"Which low value\" refers to the compressor inlet pressure; when this pressure drops to a certain level, the system switches to an inlet pressure control mode, closing the valves in order to keep the compressor inlet pressure above the safety limit ； When the inlet pressure rises, the pressure control circuit opens the valve wider, causing the compressor outlet pressure to increase; once it reaches a certain level, the system switches to an outlet pressure control system. Tuning method: 1. Two-step tuning method: First, tune the parameters of the secondary circuit, and then tune those of the primary circuit. 2. One-step tuning method: First set the parameters of the secondary circuit, and then determine the parameters of the primary circuit in one step. One tip: The auxiliary controller should eliminate disturbances quickly, which is reflected in the word \"quickly\"; the smaller the proportional band, the better. In other words, the larger K is, the faster the regulation occurs, so the auxiliary PID functions as a proportional controller. •For further discussions on “PID settings for cascade systems,” please refer to this post: PID parameter settings for cascade control of control valves http://bbs.hcbbs.com/thread-130209-1-1.html. This post was last edited by Mobei Yihai on 2009-3-25 at 11:58
1. Rely on inlet flow to prevent surge and ensure the safe operation of the unit. 2. Handle the secondary aspects first and then the main ones; refer to floor 3.