How to commission cascade control
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Level is the primary factor, flow rate is secondary – how can it be operated stably?
First, manually adjust the liquid level to stabilize it； First, activate the secondary circuit, that is, the flow control circuit, to check if it is working properly ； Reconnect to the main circuit, that is, the level control circuit.
First, observe whether the PID parameter settings for each regulator are appropriate, and whether the measurement parameters are accurate； Set the secondary circuit flow regulator to automatic mode, and enable cascade control for the primary circuit
To ensure stable operation right after it is put into use, it is necessary to manually adjust the flow rate to keep it stable. This can be done based on experience; for example, if the flow rate at this load level is 7 liters per unit time, then it should be adjusted to 7 liters per unit time. After observing for a while, once both the incoming and outgoing flow rates remain stable, the system will also be stable. At that point, cascade control can be activated.
Liquid level and flow rate in a cascade control system: simply put, it involves the relationship between the tank’s liquid level and the discharge flow rate. When the liquid level is high, the flow rate increases naturally. The cascade control can be set up in this way – the flow rate can be adjusted automatically (or manually) to maintain an appropriate level, thereby keeping the liquid level stable. It’s important to enable automatic or cascade control only when the system is already stable; otherwise, it will be difficult to achieve stability. The output related to the liquid level should match the set value for the flow rate; if not, adjustments should be made to bring them into alignment. After that, the flow rate control can be switched to cascade mode, while the liquid level control remains in manual mode to monitor whether the liquid level stays stable. Once stability is achieved, the liquid level control can be switched to automatic mode, completing the cascade control setup. Stability here refers to a relatively stable condition, with no significant fluctuations