“…To get the theoretical model, some assumptions have to be given as follows , and then a simplified model of the water tank system can be obtained.Assumptions. - The time‐lag of the electric control valves is ignored.
- The coupling between the inlet flows of Tank I and Tank II is ignored.
- α 1 and α 2 in (2) are simplified as constants.
- β 1 and β 2 in (3) are also simplified as constants.
First, considering the mass balance , the dynamic equation of each tank can be given as where y 1 and y 2 are the liquid levels, S 1 and S 2 are the cross‐sectional areas, Q i 1 and Q i 2 are the inlet liquid flow rates, Q o 1 and Q o 2 are the outlet liquid flow rates of Tank I and Tank II, respectively. According to Bernoulli's law for a non‐viscous, incompressible fluid in steady flow, the following simplified equations can be obtained under the assumptions above where u 1 (0% ~ 100%) and u 2 (0% ~ 100%) are the opening of the electric valves Ev I and Ev II, respectively; α 1 , α 2 are proportionality factors that depend on the coefficients of the electric control valves Ev I and Ev II, the pumping frequency, and the liquid level in Tank III, etc; and …”