Performance Analysis of the Level Control with Inverse
Response by using Particle Swarm Optimization
I.M.Chew
1
, F.Wong
2
, A.Bono
2
, J.Nandong
1
, and K.I.Wong
1
1
Curtin University Malaysia, Sarawak, Malaysia
2
Universiti Malaysia Sabah, Sabah, Malaysia
chewim@curtin.edu.my
Abstract. Boiler is an important utility system to support operations in the indus-
try. The control of water level in the steam drum is a complicated task due to the
non-minimum phase (NMP), which possibly will cause instability to the con-
trolled water level in the steam drum. Process identification and controller design
are difficult tasks for the steam drum because of non-minimum phase. Following
the previous literature, this paper proposed process identification to 3
rd
order
transfer function and optimization of Proportional-Integral-Derivative (PID) tun-
ings of the water level by using Particle Swarm Optimization (PSO). A Graphical
User Interface (GUI) has been developed to provide a direct platform to deal with
these tasks. The result of PSO is compared with other tuning methods in terms of
performance indicator and index. An analysis of the performance curve in 3-di-
mension graphs is also presented to visualize the output performance of various
proportional and integral gain settings. The study has concluded that PSO pro-
vided better PI tunings for the best control of the Heat Exchanger function in the
LOOP-PRO software.
Keywords: Non-minimum phase, PID, Process Identification, Particle Swarm
Optimization, Optimum Tuning.
1 Introduction
In the industry, boiler plant is widely used to support the process’s operation. It provides
heated and pressurized steam to rotate turbines for generating electricity as well as
heated steam to many downstream processes. Controlling water level is the primary
objective to ensure stable operations. However, rapid changes in the steam load and
feedwater supply to the steam drum causes high volatility of the water level.
When steam load has decreased, the pressure in the steam drum is increased and
thus, reduces the volume of the entrained vapour bubbles and thereby decreases the
water level known as the shrink effect. Whereas, the increase of the steam load causing
more volume of entrained vapour bubbles and creates the swell effect.
Apart from it, feedwater load also creates the swell and shrink effect in the steam
boiler drum. The increment of feedwater load causes decreasing of water’s temperature
and reduced the volume of entrained bubbles [1]. With the constant heat supply, the
water level will start the volume of entrained bubbles increases back to be a part of the
© Springer Nature Singapore Pte Ltd. 2020
R. Alfred et al. (eds.), Computational Science and Technology,
Lecture Notes in Electrical Engineering 603,
https://doi.org/10.1007/978-981-15-0058-9_6
55