Oxygen control in a wastewater treatment plant using adaptive predictive controllers
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Oxygen control in a wastewater treatment plant using adaptive predictive controllers Gregor Kandare, Jozef Stefan Institute, Slovenia
description
Oxygen control in a wastewater treatment plant using adaptive predictive controllers. Gregor Kandare, Jozef Stefan Institute, Slovenia. Adaptive predictive control. Process description. 6 pools with butterfly valves and 2 dissolved oxygen sensors each. - PowerPoint PPT Presentation
Transcript of Oxygen control in a wastewater treatment plant using adaptive predictive controllers
Oxygen control in a wastewater treatment plant using adaptive
predictive controllers
Gregor Kandare, Jozef Stefan Institute, Slovenia
Adaptive predictive control
SET POINTDESIREDOUTPUT
PROCESSOUTPUT
CONTROLSIGNAL
DRIVER CONTROL
BLOCKBLOCKPROCESS
ADAPTIVE
MECHANISM
EXPERT
BLOCK
Process description
6 pools with butterfly valves and 2 dissolved oxygen sensors each.
4 blowers with diffuser for pressure control.
Process description
Process description
Control issues
Biological dynamics of the process Aleatory operation context Lack of process information Interactive nature of the process
Control objectives Maintain the dissolved oxygen signal at its
setpoint by manipulationg the aeration with butterfly valves.
Maintain the air pressure in the main air conduct at a setpoint that minimises energy consumption and assures good oxygen control.
Control strategy
6 controllers – one for each pool
Adaptive predictive controller
Biological reactor
Oxygen setpoint
PV: Oxygen
Measured disturbance:air flow
Valve opening
PID control
Oxygen and valve opening
PID control
Air pressure and airflow
Adaptive predictive control
Oxygen and valve opening
Adaptive predictive control
Air pressure and airflow
Oxygen control evaluation
Reactor PID AP Factor
1 0.3974 0.1863 2.13
2 0.6632 0.2528 2.62
5 0.5221 0.1432 3.65
6 0.9138 0.151 6.05
Energy optimisation
Objectives: Maintain air pressure at a minimal level which
still permits satisfactory oxygen control. Maintain dissolved oxygen setpoints at a
minimal level that ensures required effluent
water quality.
Pressure optimisation
Pressure optimisation
Pressure optimisation
Pressure optimisation
Change PID – adaptive predictive
Energy consumption estimation
dVpdW W – energy, p – pressure, V - volume
VpdtdV
pdtdW
P P – power, ΦV - airflow
1
0
)()()( 1
t
t
V dtttptW W – consumed energy in each pool ina time interval [t0,t1]
Consumption reduction
Pool
Average power consumed with PID control
Average power consumed with AP control with pressure optimisation
Average energy savings [%]
Pool 1 51.36 42.25 17.74
Pool 2 61.55 34.97 43.18
Pool 5 67.63 52.28 22.70
Pool 6 54.47 41.98 22.93
Total 235.01 171.489 27.03
Conclusions The adaptive predictive controllers stabilise the
process and maintain oxygens at therir setpoints
More stable oxygen control and pressure setpoint optimisation decrease energy consumption by 15-23 %
