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Automatic generation control and monitoring the mechanism of micro hydro
power plant with impulse turbine and synchronous generator
Conference Paper · November 2016
DOI: 10.1109/ICRAI.2016.7791249
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World University of Bangladesh
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Automatic Generation Control and
Monitoring the mechanism of Micro Hydro
Power Plant with Impulse Turbine and
Synchronous Generator
Nazib Sobhan, arnob.ottoman@gmail.com, +88 01764367591
The classification of hydropower scheme is given below
[9]:
Abstract: This paper presents automatic generation
control and monitoring operation of Micro Hydro
power plant (MHPP), based on Impulse Turbine,
synchronous motor with permanent magnet and a servo
control spear valve. The key objective of this system is
to show the benefits of automatic generation control and
Human Machine Interface (HMI) for MHPP. Mainly,
turbine governing system covers the automatic
generation part. A deflector and a servo valve are used
for turbine governing system and PID controller is used
to adjust with the generator output. The PID controller
is used for the deflector and servo valve. The PLC is
used to control the whole mechanism and SCADA is
combined with PLC for monitoring and supervising the
system. The proposed scheme is verified with severe
MATLAB simulation result and finally a small project
confirmed the feasibility of this model. The output
results of both simulation and real model proves that
this model can work properly in real system.
Generation
Large
Small
Mini
Micro
Pico
1.
2.
3.
4.
5.
INTRODUCTION
Can be used for rural area electrification which area
are far from national grid
The construction of Dam or weir is not costly as large
dam
The low environmental impact
The plant installation can be done in a short time and
also not complicated
The equipment cost is not high compare to other
hydro project.
Now a days, PLC is used for computer based automatic
control and supervising the micro hydro power plant. The
concept is taken from Mae-Ngat hydro power plant under
responsibility of the Electricity Generating Authority of
Thailand (EGAT) [8]. The basic difference of existing
model and proposed model is the type of turbine. In Mae
Ngat the Kaplan turbine but in proposed model Pelton
wheel type Impulse Turbine is used. This turbine is much
easier to control than Kaplan Turbine. The PLC and
SCADA is applied on an existing model built by both AIT
Water Engineering Management (WEM) and Energy
Department. The several experimental results from the
existing model data indicate that the proposed turbine
control system can work properly.
Hydro power technology is the most widely
technology among others renewable energy. More
than 19% of the world’s electricity is coming from this
sector. However, a large potential of hydropower
scheme remains unexploited. This is because,
implementation of mini hydro schemes with
conventional hydraulic, electrical equipment and
controllers are very expensive and uneconomical. To
solve this problem alternative options and new designs
have been developed by the engineers and researchers.
The application of this modified new design would
reduce the cost of mini hydro schemes.[1,2,3,4,12] As
a result, many developing countries like Thailand,
Laos and Bangladesh can use this scheme for rural
electrification where interconnection of transmission
line from electrical grid is uneconomical. For this, it
would be now possible to use more renewable energy
sources than before.
978-1-5090-4059-9/16/$31.00 ©2016 IEEE
Transmission
National Grid
National Grid
Micro Power Grid
Micro Power Grid
Only for Domestic
Use
Among them Micro Hydro Scheme is more popular. The
benefits of Micro Hydro Scheme are given below:
Keywords: Impulse Turbine, Servo Valve, PLC, HMI
and PID
I.
Capacity
1000 MW <
Up to 25 MW
Below 1MW
6kW -100KW
5 KW>
II.
175
Plant Model Description:
Like every power plant this model includes
impulse turbine, synchronous generator and servo
valve as controlling equipment. Moreover, there
is other equipment that is not described in this
paper. The proposed schematic model is given
below:
The Impulse Turbine model is given below:
Fig.2 Mathematical model of Turbine
The mathematical formulation of Impulse Turbine is given
below in details:
The Input Power Coefficient is,
Fig.1 The proposed Plant Model
Cin =
2'PQ
{ρ(v +U 2 )blrb N rb v}
2
Efficiency,
At first the water is flowing to the turbine from the source
(River, Fall) through the Dam or Weir. Then water energy
is converted to water energy to mechanical energy. The
formula of this conversion is given below:
η=
Tω
ΔPQ
I=
v
U
Flow coefficient,
Pw= (1/2)
ρAV3
Where,
Here,
T=Torque, ρ=Density, v=Inlet velocity, U=
Circumferal velocity, P=Pressure, Q=Flow rate, ∆P=Total
Pressure Drop, r=Radius of the turbine, l=total length,
N=Number of blades=blade height, k=Torque Constant.
ρ =Water Density (1000 kgm-3),V= Water Speed (ms-1),A=
water turbine rotor swept area (m2)
and
Cp=
Tt u Z
0.5 u A uV 3
The initial output curve of the turbine is given below:
Cp= Power Coefficient of performance
The water turbine torque is given by,
P
T =
S W
s
Input
Power
Fig.3 The Output curve of Turbine Model (Impulse
Mode)
Ts=Torque of water turbine
Generator Model:
Most of the small or micro hydro sites, synchronous
generator is most preferable, because it has stable, good
characteristics during normal operation and they do not
need an additional DC supply for the excitation.
P= Power of water turbine
Ws=rotor speed of water turbine
1.
Turbine Model:
The generation capacity of hydropower plant
depends on the turbine efficiency. Hence, choose
of turbine in hydro power site is very important
[8]. Recently, a new design of Impulse turbine
model is invented that gives more flexibility and
reliability.
978-1-5090-4059-9/16/$31.00 ©2016 IEEE
Model of Servo Valve:
Servo valve is main control element in micro hydro plant.
Mainly, this valve is used to control the water flow through
dam to turbine. As a result the output power of the prime
mover can be controlled [11].
176
The mathematical model of servo motor control valve is
given below:
The resultant monitoring panel is given below:
1. Home Screen Panel
Fig.4 Mathematical Model of Servo
Motor Control Valve mechanism
Where, Kv=Valve Gain, Tv=Time rate of valve
Results and Discussion:
The results and output are given in some matlab simulation
curves and the SCADA models. The respective parameters
of the plant is given below:
Turbine Flow rate,Q=0-0.11m3/s
Generator Speed range=0-1200 rpm
Output Power=0-4.8 KW Rated Speed (t) =1500 rpm
Input Torque,Tm=37.2 Nm
Damping factor, Kd=0.026
Rated Power,Pe=5.5 KW
Efficiency at rated speed, ƞ=0.9
Rated voltage, V=400V
Rated Current, I=7.9A
Fig.6 The main Home-Screen Panel of MHPP
2.The AGC panel is given below:
The final resultant curve is given below:
Over Voltage
Voltage
Gain
Normal
Operation
Under Voltage
Time
Fig.5 Load changing affect and frequency deviation of
the system
From , the swing equation it is shown that the change of
rotor speed is depend on the difference of input mechanical
power and output electrical power. The main variable is
turbine input power which is depend on water flow.hence,
in this model the governor is used to control the flow and
thus controlling flow is the prime mechanism of automatic
generation control (AGC).
978-1-5090-4059-9/16/$31.00 ©2016 IEEE
177
Fig.7 The various parameters of MHPP
3. The PID monitoring panel is given below:
RESULTS&DISCUSSION:
In this section, some of output graphs of the proposed
micro hydro model is given which describe the system
operation and analysis of the total system. Some of the
graphs are given below:
In this curve the change of input and output power analysis
in accordance to the flow rate is discussed. The power
analysis curve is given below:
Fig.8 The monitoring model of PID application
The proposed experimental set up is given below:
Figure The change of head water level
In this curve the change of input and output power analysis
in accordance to the flow rate is discussed. The power
analysis curve is given below:
Figure 9 The proposed experimental set up
This is the schematic diagram of the whole control system.
The following flow chart describes the whole control
mechanism:
The Input is coming
from Voltage &
Current from the
manual Circuit
The Valve
is finally
rotate by
stepper
motor and
makes
perfect
position
PLC OUTPUT is
connect with
ARDUNIO
Driver circuits
run the motor
with pulse
signal and
direction
coming from
the driver
circuit
978-1-5090-4059-9/16/$31.00 ©2016 IEEE
Figure Rate of change of power with input water flow
PLC
OUTPUT is
connect
with
ARDUNIO
ARDUNIO step
signal is used for
making proper
Pulse for the
Driver Circuit
The turbine and generator are connected with common
rotor. The output speed and frequency is significant for the
model. The speed analysis curve is given below
Speed and frequency changing Curve
178
6.
Duangsoithing T., Kongnam C. Renovation of
Turbine Control System Using PLC-Based for
Small Hydroelectric Power Generation. Brief
Report on Mae-Ngat Hydro power plant by
Electricity Generating Authority of Thailand
(EGAT).
7. Operational description of Pump as a turbine
from AIT-EHMF Collaborative Project on Micro
Hydro system at Asian Institute Of technology,
Thailand.
8. Turbine and hydropower modeling project by
SINTEF Energy Research in 2005.
9. Hydraulic Turbine and turbine Control Model for
system dynamic studies under IEEE system
dynamic performance. Established in 1977.
10. A. Williams (1996), “Pumps as turbines for low
cost micro hydro power”, Renewable Energy
Journal, Volume 9, Issues 1-4, pp.1227-1234.
11. Dolla and Vatti (2006), “ Automatic generation
control of an isolated small-hydro power plant”
Electrical power system research 76(2006) 889896.
12. Handmandlu and Goyal (2008), “Proposing a
new advanced control technique for micro hydro
power plants.” Electrical Power and Energy
Systems 30 (2008) 272-282.
CONCLUSION:
This paper is focused on the control technique of MHPS.
The automatic generation control which is formed by
computerized control technique recovers the faults and
crisis very quickly and effectively. This paper focus on
PLC as computerized tool for system control. For
validation, a small project is built as a real model.
However this model cannot be done in real hydro site due
to lack of budget. The simulation data is taken from the
output result of the experiment in a joint venture project of
Water Engineering Management (WEM) and Energy
Department in AIT. Finally, there are recommendations
like transformer connection and grid fault can be
considered in future work. Moreover, highly
communication devices like Ethernet and Optical fiber can
be used for Stand-alone MHPS.
REFERENCES
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5.
Kishor N., Singh N, Raghuvanshi A. (2006).
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Laghari J., Mokhils H., Bakar A., Mahammad H.
(2012).A comprehensive overview of new
designs in the hydraulic, electrical equipments
and controllers of mini hydro power plants
making it cost effective technology. Renewable
and sustainable Energy reviews,.
Li L., Ma R. (2012).Design and Analysis of
Comprehensive Control System for Hydro
turbines. AASRI Procedia,.
Marquez J, Molina M, Pacas J (2010).Dynamic
modeling, simulation and control design of an
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978-1-5090-4059-9/16/$31.00 ©2016 IEEE
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