FYP Report up to date COMPLETE

Pumped Hydro
Storage
By
Mr. Steven Sweeney
A project submitted in partial fulfilment requirements
For a
B.Sc. Renewable and Electrical Energy Systems
Limerick Institute of Technology
Submitted: 12/04/15
Supervisor: Mr. Ed Mullen

Pumped Hydro Storage Steven Sweeney K00181764
Renewable & Electrical Energy Systems 3rd Year FYP Page 2
Declaration
I Steven Sweeney declare that this thesis on the research and build of a Pumped
Hydro Storage demonstration is my own work, and has not been submitted in any
other form for another award at any institution of education. Information taken from
the published or unpublished work of others has been acknowledged in the text and
a list of references is given.
Signed: ____________________ Signed: _________________
Steven Sweeney Ed Mullen
(Candidate) (Supervisor)
Date: ______________________ Date: ___________________
Dedication & Acknowledgements
I would like to dedicate this thesis to all the members of my family and my Fiancée
for all their support throughout the process of completing this final year project. I
would also like to thank my supervisor Mr. Ed Mullen and lecturers Mr. Pat Grace
and Mr. Keith Moloney for their much appreciated help and advice.

Abstract
This project was completed to give the reader an in-depth understanding of the
operation of Pumped Hydro Storage and how valuable it can be as a storage hub for
different types of renewable energy resources. Ireland has not reached its full
potential in tapping into its own offshore wave and wind resources but has among the
best in Europe. The problem with renewable energy resources like wind and wave is
that they are highly variable and a lot of times are not in sync with demand. Therefore
instances such as curtailment come about and power is dumped because there is no
demand for it. This is where it is believed Pumped Hydro Storage can play a crucial
part in stopping power being dumped by simply using that surplus power to pump
water from a lower reservoir to an upper reservoir to be stored as potential energy for
use when required. This is a conversion of the over produced electrical energy into
potential energy which is then converted back to electrical energy but at a time when
needed.
In this thesis the research section chapter 2, goes into a lot of detail surrounding the
operation of a Pumped Hydro Storage plant; its different applications and a small
case study on Ireland’s only plant, “Turlough hill”. Chapter 3 gives an insight into how
a small build demonstration was planned out to perform as much of the same
features as a real Pumped Hydro Storage plant within certain size limitations. It also
showed the plans for the wiring requirements along with the PLC ladder code used to
control the process. Chapter 4 was the build phase, which shows how the
demonstration was put together from start to finish along with any challenges and
trade-offs that were faced. The demonstration was tested in chapter 5 and it was
discovered that the small DC generator was only producing 0.14W of power.
However, to find the relevant efficiencies the same principals were applied to testing
this project as would be applied in a real plant. The overall efficiency was very poor
because of a number of factors such as head height, the type of turbine and the
efficiency of the generator. This project did however meet its goal by successfully
lighting 3 LEDs totally independent of any other power source. Chapter 6 provided a
brief break down of some of the risks that could happen when demonstrating this
demo rig. The conclusion of this thesis offers some of the problems faced throughout
with some recommendations that would have further advanced this project.
.

Contents
Declaration................................................................................................................ 2
Dedication & Acknowledgements .............................................................................. 2
Abstract..................................................................................................................... 3
1 Introduction ........................................................................................................ 8
2 Background Information (Research)................................................................... 9
2.1 Hydro Power ............................................................................................... 9
2.2 Why choose Pumped Hydro Storage?....................................................... 10
2.3 How Pumped Hydro Storage works........................................................... 11
2.4 Irelands Potential for Pumped Hydro Storage............................................ 12
2.5 Typical 24hr power demand in Ireland....................................................... 13
2.6 Pumped Hydro Storage’s different applications ......................................... 14
2.7 Advantages of Pumped Hydro Storage ..................................................... 14
2.7.1 A black start ....................................................................................... 14
2.7.2 Disadvantages of Pumped Hydro Storage.......................................... 15
2.8 Europe’s largest Pumped Hydro Storage plant.......................................... 15
2.9 Ireland’s only Pumped Hydro Storage plant............................................... 15
2.10 Small Case Study on Turlough Hill ............................................................ 16
2.10.1 Environmental Impact......................................................................... 16
2.10.2 Generating Power .............................................................................. 17
2.10.3 The Reversible Turbine ...................................................................... 17
2.10.4 The Irish electricity grid....................................................................... 18
2.10.5 Hydro Electric Control Centre for Ireland ............................................ 19
2.10.6 How Turlough Hill Controls Ireland’s Hydro Generation...................... 19
2.11 Pumped Hydro Storage demo (build & control).......................................... 20
2.11.1 Controlling the Process ...................................................................... 20
2.12 The DC generator...................................................................................... 21
2.13 The Pelton turbine runner.......................................................................... 22
2.14 Programmable Logic Controller................................................................. 22
2.14.1 The PLC internal components ............................................................ 23
2.15 Supervisory Control and Data Acquisition (SCADA) .................................. 25
2.16 PLC based system .................................................................................... 26
2.17 The importance of variable tags in SCADA................................................ 27
3 Project finalised design..................................................................................... 28
3.1 The method of the project.......................................................................... 28
3.1.1 Flow chart of finalised design ............................................................. 29

3.2 Inputs & outputs list (I/O list)...................................................................... 30
3.3 The PLC ladder program........................................................................... 31
3.4 The selected components ......................................................................... 34
3.5 PLC wiring diagram................................................................................... 37
3.6 Material required & costing........................................................................ 38
4 The build process............................................................................................. 39
4.1 Creating the upper & lower reservoirs ....................................................... 39
4.2 The movable frame ................................................................................... 40
4.2.1 Constructing the frame ....................................................................... 40
4.3 Attaching the limit switches........................................................................ 41
4.3.1 The actual volume of water in the upper tank ..................................... 41
4.4 The plumbing phase.................................................................................. 42
4.4.1 Editing key areas of plumbing phase.................................................. 43
4.5 Constructing the turbine unit...................................................................... 44
4.5.1 Testing the generator and attaching all necessary parts..................... 44
4.6 Electrical Phase......................................................................................... 46
4.6.1 Wiring the control panel & PLC........................................................... 46
4.6.2 Wiring the demo rig’s devices............................................................. 47
4.7 Installing the serial to USB PLC software .................................................. 49
4.8 Connecting the level sensor ...................................................................... 49
4.9 Supplying the LED load............................................................................. 51
4.10 The complete build design......................................................................... 51
4.11 Implementing Citect SCADA...................................................................... 52
4.12 Skills developed & challenges ................................................................... 55
5 Project testing................................................................................................... 56
5.1 Determining the average flow rate............................................................. 57
5.1.1 Generating efficiency.......................................................................... 57
5.1.2 Energy capacity storage..................................................................... 58
5.1.3 Pumping efficiency ............................................................................. 58
5.1.4 Overall efficiency of the project........................................................... 58
6 Risk assessment .............................................................................................. 59
7 Conclusion ....................................................................................................... 60
8 References....................................................................................................... 62
9 Appendices ...................................................................................................... 65
9.1 Appendix A: Irelands Grid Network............................................................ 65
9.2 Appendix B Material and quotation sheet from MIKO Metals ..................... 66

9.3 Appendix C Solenoid valve data sheet and quotation................................ 67
9.4 Appendix D The data sheet for Etape level sensor .................................... 70
9.5 Appendix E Information on the water pump............................................... 72
9.6 Heat merchants quotation ......................................................................... 73
9.7 Appendix F Extra pages in SCADA ........................................................... 73
9.8 Appendix G Meeting minutes..................................................................... 75
Figure 1: Irelands mixed use of fuel generation ....................................................... 10
Figure 2: A Pumped Hydro Storage Plant in operation ............................................ 11
Figure 3: Ireland’s wave & wind resource ................................................................ 12
Figure 4: Typical graph of the power demand for a day in October.......................... 13
Figure 5: Arial view of Turlough Hill ......................................................................... 16
Figure 6: Reversible Turbine Design ....................................................................... 17
Figure 7: Construction of a Francis Turbine............................................................. 18
Figure 8: A typical Control System as used in Turlough Hill..................................... 19
Figure 9: Project design & Equivalent CAD Drawing................................................ 20
Figure 10: Construction of a DC generator .............................................................. 21
Figure 11: The Pelton turbine runner ....................................................................... 22
Figure 12: Mitsubishi FX2C PLC.............................................................................. 22
Figure 13: FX-4AD Module...................................................................................... 23
Figure 14: Basic layout of a PLC’s components....................................................... 23
Figure 15: Internal Opto-isolator.............................................................................. 24
Figure 16: SCADA programming ............................................................................. 25
Figure 17: 5 tasks of SCADA................................................................................... 25
Figure 18: PLC based SCADA system .................................................................... 26
Figure 19: SCADA graphics..................................................................................... 27
Figure 20: The submersible water pump.................................................................. 34
Figure 21: Automatic valve Vs manual valve ........................................................... 34
Figure 22: The Milone eTape level sensor............................................................... 35
Figure 23: The DC generator................................................................................... 36
Figure 24: The 3 LED’s supplied by generated power ............................................. 36
Figure 25: PLC wiring layout.................................................................................... 37
Figure 26: The FX-4AD wiring diagram.................................................................... 37
Figure 27: Fitted the limit switches........................................................................... 41
Figure 28: Connecting the valve & the pump ........................................................... 42
Figure 29: Bending & offsetting the pipe work.......................................................... 42
Figure 30: Testing the pump.................................................................................... 42
Figure 31: Making the necessary changes to the penstock...................................... 43
Figure 32: Fitting a shield over the turbine............................................................... 43
Figure 33: Making the runner................................................................................... 44
Figure 34: Attaching all the turbines components .................................................... 44
Figure 35: Turbine in position .................................................................................. 45
Figure 36: Arranging the control panel's components .............................................. 46
Figure 37: Terminating the inputs & outputs ............................................................ 46
Figure 38: Control panel complete........................................................................... 47

Figure 39: Attaching the trunking & junction box...................................................... 47
Figure 40 Termination box....................................................................................... 48
Figure 41: Soldering the connection points.............................................................. 48
Figure 42: Downloading the brain box serial to USB software.................................. 49
Figure 43: Soldering components to a Vero board................................................... 49
Figure 44: Checking the level sensor works before installation................................ 50
Figure 45: Securing the level sensor ....................................................................... 50
Figure 46: Checking to see if it is best to wire LED’s in parallel or series................. 51
Figure 47: The completion of the build..................................................................... 51
Figure 48: Setting up the users & roles in SCADA................................................... 52
Figure 49: Setting up clusters and servers............................................................... 52
Figure 50: Setting up the I/O device ........................................................................ 53
Figure 51: Example of a variable tag (Integer)......................................................... 53
Figure 52: Building the graphics page...................................................................... 54
Figure 53: The completed graphics page................................................................. 54
Figure 54: Voltage and current output from the generator........................................ 56
Figure 55: Measuring the average flow rate............................................................. 57
Table 1: I/O list for the different devices................................................................... 30
Table 2: Price list for components used................................................................... 38
Table 3: Risk assessment break down .................................................................... 59

1 Introduction
This project was based on the principal of how a Pumped Hydro Storage plant
produces and distributes electricity. A Pumped Hydro Storage plant recycles a
specific volume of water between an upper reservoir and lower reservoir as part of
the process to generate power when needed. This project was designed to convert
the hydraulic potential energy of the water stored in the upper reservoir into
mechanical energy to turn a small DC generator to create electrical energy sufficient
enough to drive a small load. This load represents a consumer requiring power
during specific times of day when power is in high demand, known as peak time
demand. Peak demand is when power is at the best price for the supplier to sell, as
price increases with demand. When off peak time commences, usually late at night
or early morning there is an excess generation of power being produced by power
generation stations and wind farms all around the country with a limited requirement
for power by consumers. Off-peak time is the best time to purchase power, as power
is at a lower tariff rate. This continuously varying demand for power is a key aspect in
the operation of a Pumped Hydro Storage plant and is what led it to be such a
commercial success. In a Pumped Hydro Storage plant the generator that supplies
power at peak time changes into reverse to become a motor (pump) and consumes
power at off-peak time. The motor now pumps water from a lower reservoir back to
an upper reservoir. This process consumes power from the grid at the off peak time
tariff. By understanding the theory of how a Pumped Hydro Storage plant operates, a
small scale Pumped Hydro Storage demo rig was constructed to show how Pumped
Hydro Storage works with a level of control that would be something similar to a real
plant.
This project was chosen because it is a very interesting topic and deserves the
recognition to show the potential it has to be part of the future progression of
renewable energy systems and improving the efficiency of conventional generation
systems. A Pumped Hydro Storage plant has the potential to become a store for
surplus power currently being produced everyday from conventional power
generation plants. A Pumped Hydro Storage plant can become the main hub in a
network to store the over production of energy from other types of renewable sources
that aren’t capable of commercially storing large amounts energy themselves. The
Pumped Hydro Storage demo rig constructed for this project was controlled by a
programmable logic controller (PLC) which helped provide a good learning and
understanding of how to control and fully automate a project very similar to one seen
in industry. The PLC used was a Mitsubishi FX2C. The ladder logic diagram was
created using GX works2 software and transferred to the PLC once complete. The
entire project was mounted on a movable frame with four wheels that lock to give it
stability. This system was fully automated using SCADA to show the entire process
clearly on a computer screen. This report along with the build demonstration and
three presentations at different phases throughout the project will give a clear
understanding of how Pumped Hydro Storage works and how beneficial it can be as
an energy storage facility.

2 Background Information (Research)
This section will provide background information relevant to Pumped Hydro Storage.
Research was sought through various different sources and combined together
throughout chapter 2.
2.1 Hydro Power
Hydro power is the conversion of water falling or moving downhill due to gravity into a
useful form of mechanical energy to turn a turbine. The mechanical energy of the
turbine is then converted into electrical energy that gets distributed by transmission
lines. As is normal with every conversion there are losses and factors that will have
an impact on the efficiency which in turn will have an impact on the power output.
The equation listed below shows how the output power can be calculated.
 P = Power in Watts
 η = Efficiency of the turbine
 ρ = The density of water in kilograms per cubic metre
 Q = The flow in cubic metres per second
 g = The acceleration due to gravity
 h = The height difference between inlet and outlet in metres
(Wikipedia, 2014)
Hydropower is a well established, proven technology that has been around for over
100 years and accounts for 90% of all renewable energy sources that contribute to
the world’s energy supplies. Hydroelectricity can give a variable output with the
changing of seasons i.e. more rain in winter than in summer. This means that careful
planning is required in sizing a system to get the maximum output from a selected
turbine (Boyle, 2004).
Pumped Hydro Storage is a form of Hydroelectricity that is unique in the way it
provides a constant controlled output irrelevant of the time of year.

2.2 Why choose Pumped Hydro Storage?
Pumped Hydro Storage is currently the only commercially viable and economic way
of storing large quantities of electrical energy. This makes it extremely important to
the renewable energy sector and to the continual growth of renewable energy in
Ireland. Ireland is a very small country with a lot of natural energy resources at its
disposal. As Ireland is part of the European Union it must comply with some of the
targets set out by Europe to help lower the world’s contribution to climate change by
reducing Carbon emissions. Ireland has identified the generation of electricity by its
many power stations as a key area that needs changing. Ireland has set targets to
supply 40% of its gross electricity demand by renewable energy sources by the year
2020 to meet Europe’s requirements (Boyle, 2004) (Sustainable Energy Authority of
Ireland, 2014).
The concept of having so much of Ireland’s demand for power met by renewable
resources is a massive step in the right direction. The downside however is that
Ireland’s energy resources are highly variable and sometimes the many wind farms
now in operation are not in sync will the Country’s peak load demand. If a wind farm
is not receiving enough energy from the wind to produce the power required, then
power must be sourced elsewhere by other generation stations or indeed a Pumped
Hydro Storage plant. Another key aspect of how Pumped Hydro Storage
compliments wind energy in Ireland is by avoiding curtailment (which is when wind
energy is available to the grid from a wind farm but the grid doesn’t require it and
therefore must be dumped with the wind farm being compensated). A Pumped Hydro
Storage plant plays a pivotal role in avoiding unnecessary costs of curtailment by
being an energy store for Irelands many wind farms that have surplus power
available (Sustainable Energy Authority of Ireland, 2014).
Figure 1: Irelands mixed use of fuel generation
As seen in figure 1, Ireland is heavily dependent on importing fossil fuels to generate
electricity which is costing the economy €6.7 billion annually. Due to this high
dependence, Irish citizens are exposed to prices set by external means in the global
market and can cause a lack of security of supply. Renewable generation in Ireland
has been increasing year on year and in January 2015 wind generation reached
33%, which is one of the highest in the world. However variability is a key factor in
renewable generation when trying to match supply with demand or having to come
up with a means of energy storage. Pumped Hydro Storage is an ideal application to
keep renewable generation in Ireland on the upward trend for the future (Lumcloon
Energy , 2015).

2.3 How Pumped Hydro Storage works
Figure 2: A Pumped Hydro Storage Plant in operation
(Boyle, 2004)
Figure 2 illustrates how a Pumped Hydro Storage plant operates at different times
over the course of a day. A Pumped Hydro Storage plant is a way to store energy. It
consists of two reservoirs, one upper and one lower and a reversible turbine. As seen
in picture B. Power is produced during the day to supply consumer requirements,
known as peak time and is the best time to be generating power because power is at
its most expensive rate to buy. Power is produced by opening the intake gate to allow
the stored potential energy in the water to flow down the penstock and rotate the
turbine that then drives the generator. Most of the energy of the water goes in to
rotating the turbine and then collects in the lower reservoir below.
Picture A shows the operation during the night, which is known as off peak time. This
is the time of day when there is very little demand for power but there is an over
production due to the fossil fuel power stations being run at full output all the time
and due to the variability of the wind farms overproducing with nowhere to store their
surplus power. Off peak time is also when power is at its cheapest rate to purchase
and is the time when a Pumped Hydro Storage plant is most beneficial by changing
its reversible turbine into a pump that now consumes the surplus power readily
available at a reduced cost. The reversible turbine takes the water earlier deposited
in the lower reservoir and returns it back to the upper reservoir to be stored once
again as potential energy. It could be said that a Pumped Hydro Storage plant works
on the same principal as charging a battery. The whole plant is controllable and can
be up and running at full output in a matter of seconds, making it really beneficial to
the electricity grid (Energy Storage Association, 2014) (Boyle, 2004).

2.4 Irelands Potential for Pumped Hydro Storage
Figure 3: Ireland’s wave & wind resource
(Finfacts Ireland, 2011)
Ireland has one of the best wind and wave energy resources in Europe as seen in
figure 3. In particular, off the west coast of Ireland a proposal is currently in the
planning process to build a 1200MW Sea Water Pumped Hydro Storage plant at
Glinsk Mountain near Bellmullet off the North coast of Mayo. There is potential at this
site to generate 25000MW of electricity with combining energy sources from onshore
wind farms, offshore wave farms and the Sea Water Pumped Hydro Storage plant
itself. If this project does go ahead it will create an energy storage hub that will
accept surplus energy from these local energy producing farms and use that energy
to raise sea water from the Atlantic Ocean to the upper reservoir at the top of Glinsk
Mountain. The upper reservoir will have to be excavated to create a manmade lake
out of the boggy land that currently exists there, while the lower reservoir already
exists in the form of the Atlantic Ocean (B.E., James J. Nolan, 2012).
This project is scheduled to be completed by July 2018 and plans to export power to
supply 1.5% of the United Kingdom’s power requirements as well as providing a
much needed upgrading of the electrical infrastructure in the North West of Ireland
(see appendix A). This will create a window of opportunities to connect a network of
renewable energy systems together and help speed up the development of wind
farms near this area that have already received the necessary planning but do not
have the electrical infrastructure to deal with the amount of electricity that will be
generated. The Glinsk Sea Water Pumped Hydro Storage system works by
accepting excess wind power to pump sea water to the upper reservoir on the
mountain. The stored energy can now be used when demand is high or to help the
grid start up its generation power plants if a generation emergency occurs from
adverse weather conditions (Organic Power Ltd, 2014).

2.5 Typical 24hr power demand in Ireland
Figure 4: Typical graph of the power demand for a day in October
(Eirgrid, 2014)
The graph in figure 4 shows the variation in consumer demand for power in Ireland
over a typical day (24th
October 2014). It begins at 12:00 A.M were there is 2545MW
of power being consumed. This gradually decreases to the lowest consumption point
of 2110MW at 3:45 A.M. Unfortunately there is excess power being produced at this
time by Ireland’s fossil fuel power plants and wind farms which is not being utilised
due to the lack of demand known as off peak time. It is here that the Pumped Hydro
Storage plant would use that surplus power to supply its reversible turbine to pump
water into the upper reservoir to increase its storage capacity for later use that day.
From 06:00 A.M onwards the demand for power begins to increase and at 08:15 A.M
it rises to 3425MW of power being consumed. This is due to people waking up and
having breakfast before going to work. The power demand remains reasonably
constant until 4:00 P.M were the demand increases rapidly from 3296MW to
3743MW which is a total increase of 447MW in just three hours. It is this sudden
draw on the grids power supply that the Pumped Hydro Storage plant is usually
brought online. The Pumped Hydro Storage plant is hugely beneficial at this time as it
can be up and running at full output in less than one minute meaning that it is an
extremely useful acid to have in cases of sudden spikes in demand.

2.6 Pumped Hydro Storage’s different applications
Pumped Hydro Storage plants can be designed for several different uses. They can
be used only for emergency situations, such as the one in the Catskills Mountains in
the State of New York USA, called the Blenheim-Gilboa Pumped Storage Power
Project. In emergency situations such as damage to the electrical transmission
network caused by bad weather, earth quakes, blackouts or temporary loss of a
particular generating system, this project can be brought on line in the space of two
minutes in the event of any of these disasters occurring (New York Power Authority,
1996-2012).
Pumped Hydro Storage plants can also be used to offset a sudden spike in demand
for power such as Dinorwig in Wales. An everyday day example of a spike like this
happening would be something as simple as a very popular T.V program which
would attract a large audience watching it. When this T.V program cuts to a
commercial or finishes, the people watching usually put on their kettles to make tea.
That could potentially mean millions of kettles turned on simultaneously causing a
huge demand on the generating power plants that supply the network. This is when
having a Pumped Hydro Storage becomes Invaluable as, unlike Coal and Nuclear
Power stations a Pumped Hydro Storage plant can go from a complete standstill to
full load output in a matter of seconds. Although the Pumped Hydro Storage plant
may only have enough water in the upper reservoir to produce electricity for 5 to 6
hours before all that potential energy is exhausted, this time frame is usually
adequate enough to aid the grid dealing with these sudden spike’s in consumer
demand (The GreenAge, 2014).
2.7 Advantages of Pumped Hydro Storage
Pumped Hydro Storage is a relatively inexpensive source of generating electricity as
it doesn’t require fossil fuels for generation. It is a carbon neutral, emission free
renewable energy source that if carefully planned out can have a low environmental
impact. It is fast acting to meet consumer demand and has a controllable output with
a fast response time. In some cases a Pumped Hydro Storage plant can also be
used to help out the supply network in the event of a black start (NHA’s Pumped
Storage Development Council, 2012).
2.7.1 A black start
This is the method taken to recover complete or temporary loss of the power
transmission system which is usually caused by the failure of a power generating
station that is grid tied. This loss failed power station will now be isolated from the
grid and will require an electrical supply to restart. Some power stations do not have
the capability of providing an electrical supply from their own power plant and instead
rely on external means such as diesel generators. A Pumped Hydro Storage plant is
unique as it can keep a reserve of potential energy stored in the upper reservoir to
only use when the event of a black start occurs. This reserve can also be used to
restart a neighbouring power generating plant after the initial problem that forced that
plant to be taken off line has been resolved (The GreenAge, 2014).

2.7.2 Disadvantages of Pumped Hydro Storage
A pumped Hydro Storage plant has a high initial cost because sometimes one or
both reservoirs must be excavated; this can have a severe environmental impact. A
Pumped Hydro Storage plant is site specific because it need’s mountainous areas for
a head height to drop the water. Also the best location for installation is usually
located in remote areas which are far from the main source of the power demand.
Therefore there is a high cost installing the infrastructure because of long and large
transmission lines and electrical equipment. It is also not uncommon for a Pumped
Hydro Storage plant to consume more power than it produces (DUKE ENERGY,
2014).
2.8 Europe’s largest Pumped Hydro Storage plant
In the United Kingdom, Wales has the largest Pumped Hydro Storage plant in
Europe known as Dinorwig. Dinorwig took ten years to complete and is also the
largest man made cavern in Europe. It produces 1728MW of electricity when its six
reversible Francis turbines are in operation. Dinorwig was chosen because of the
naturally occurring high vertical drop between both its reservoirs. This meant a
massive saving on civil works. Dinorwig can go from complete stand still to full
operation in just 12 seconds. This is very significant to the United Kingdom’s grid as it
would take a coal burning power plant or a nuclear power plant at least twelve hours
to reach full output. Dinorwig produces power for a total of five hours and consumes
power for seven hours when the reversible turbines return the water back to the
upper reservoir, meaning that returning the water to the upper reservoir is more
energy intensive than what Dinorwig can produce. Dinorwig consumes 33% more
electricity than it produces. However looking at the bigger picture, the main focus is
to protect the grid’s many power generating stations by meeting the spike in
consumer demand to relieve the stresses on the supply network. Dinorwig more than
compensates for this inefficiency of consuming more than it produces with its fast
reacting response time and guaranteeing everyday controllable on demand electricity
to the United Kingdom’s grid (The GreenAge, 2014).
2.9 Ireland’s only Pumped Hydro Storage plant
In Ireland there is currently only one Pumped Hydro Storage plant in operation called
Turlough Hill located in Co. Wicklow. Turlough hill is owned and operated by the
Electrical Supply Board (ESB).
As seen earlier in section 2.4 there are plans being put in place to try and build
another Pumped Hydro Storage plant located on the west coast of Ireland.

2.10 Small Case Study on Turlough Hill
Figure 5: Arial view of Turlough Hill
Turlough hill was commissioned back in 1974 taking 8 years to complete and costing
22 Million Irish pounds (28 Million Euro). The upper reservoir was artificially made to
produce a storage capacity capable of storing 2.3 Million cubic metres of water.
Turlough hill already has a naturally occurring lake at the bottom of the mountain
called Lough Nahanagan, which was used as the lower reservoir (see figure 5). The
Hydraulic head height separating both these reservoirs is 549 Metres with an
effective head height of 285M to reach the turbines. A large underground chamber
was excavated deep inside the mountain to house the power station. Turlough hill
slightly differs from most other Pumped Hydro Storage plants because the volume of
water travelling in the penstock travels down first before rising up 15M to reach the
turbines. This would result in some friction losses and the loss in effective head
height from 300M to 285M (A.Ter-Gazarian, 2008) (ESB Ireland, 2014).
2.10.1 Environmental Impact
The environmental impact resulting from constructing Turlough hill was kept as low
as possible with some people even referring to it as invisible. This was achieved by
carefully planning and designing the upper reservoir, housing of the turbines, the
generators and the penstock to blend in with the natural surroundings of the Wicklow
mountains (ESB Ireland, 2014).

2.10.2 Generating Power
Turlough hill works on the same principal as any other Pumped Hydro Storage plant
in the way it generates power for consumers at peak time (see figure 2). Turlough hill
has four 73MW generators that are driven by a reversible Francis Turbines. The
generators between them are capable of producing 292MW of power and operate all
year round. Turlough hill is brought online usually around 5pm every day as this has
been identified as the start of Ireland’s peak demand load. The entire generating
process is capable of ramping up to full output in 70 seconds to deliver its 292MW
power constantly for 5 hours to the Irish grid until all of the stored potential energy is
used up (The Irish Times, 2014).
When Turlough hill reaches 5pm, peak time commences and the water residing in
the upper reservoir is released using large sluice gates. Water now falls 285M and
rotates its 4 reversible Francis turbines that in turn rotate the generator to produce
power lasting for 5 hours. Then at off peak time power is supplied from the grid to
reverse the Francis turbine and pump the water back up to the upper reservoir to be
stored for use the following day.
2.10.3 The Reversible Turbine
Figure 6: Reversible Turbine Design
(Eve Cathrin Walset, 2010)
The reversible turbine sits between both reservoirs and is directly coupled to the
generator/ motor as seen in figure 6. The reversible turbine runs in generating mode
when peak demand requires it to produce power. The reversible turbine then
reverses to become a motor to commence pumping mode when off peak demand
requires it to make use of the surplus power being produced on the grid. The most
commonly used reversible turbine is the Francis turbine.

2.10.3.1 The Francis Turbine
Figure 7: Construction of a Francis Turbine
Francis turbines are the best suited turbines for Pumped Hydro Storage. They can be
used in applications with head heights up to 300m. The Francis turbine is a reaction
turbine which means it is completely submerged in water and is enclosed inside a
pressure casing as seen in Figure 7. Water flows in at the inlet of the penstock and
rushes down to the spiral casing which is shaped like a snail’s shell. Inside this
casing is the runner which has specifically designed blades that allow water to flow
over them. This produces a low pressure on one side and a high pressure on the
other side and it is this pressure difference that causes the rotation. The runner is
connected to the generator through a mechanical shaft and this produces the
electricity (Boyle, 2004).
2.10.4 The Irish electricity grid
The Irish electricity grid is currently being operated by Eirgrid’s National Control
Centre (NCC) which is based in Dublin. Eirgrid’s Engineers exercise energy
management and have the task of forecasting an estimating the amount of electricity
that is required at certain times, that following day. It is important that these figures
are as accurate as possible because the load demand can vary without warning.
Therefore a lot of research must be attained on upcoming events such as football
matches and concerts around the country which might cause a change in the
demand that was not foreseen in the records from the previous year. Critical to
Eirgrid’s work are all the power generating stations which are monitored by the
Distribution Control Centres (DCCs) and the Hydro Electric Control Centre which is
located inside in Turlough hill. To monitor all these power generating stations
simultaneously the NCC requires a vast amount of online information. To make this
possible data must be collected by each power station which is achieved by using
Remote Terminal Units (RTUs) that transmit the required information back to Eirgrid
to ensure minute by minute operation of the entire Irish electricity grid (Eirgrid, 2013)
(Energy-Co-operatives Ireland Ltd, 2014).

2.10.5 Hydro Electric Control Centre for Ireland
Turlough hill has a major part to play in the Irish grid as well as being able to respond
quickly to changes in power demand. It is also the centralised hub that controls the 6
major Hydro power plants in Ireland including itself.
2.10.6 How Turlough Hill Controls Ireland’s Hydro Generation
Figure 8: A typical Control System as used in Turlough Hill
Turlough hill has now become the central control centre for all Hydro generation in
Ireland, known as the Hydro Control Centre (HCC). As seen in figure 8, it is a state of
the art control system that has provided improvements in control communication
technology developed in the last 20 years. Turlough hill has to have an operator
present all the time because of its importance to the grid when switching online and
offline as needed. This is one of the main reasons the HCC decided to set up
operations at Turlough hill. This allowed all the other Hydro plants around the
Country such as Cathleen’s falls and Cliff power station in Co. Donegal to only
operate locally on a daily 12 hour shift. These improvements in control engineering
meant at the end of a 12 hour shift the complete control of these Hydro power plants
is handed over to the HCC in Turlough Hill during the night were an operator is
always present anyway. For this level of control to be achieved each independent
Hydro plant that already has an existing level of Supervisory Control and Data
Acquisition (SCADA) present must also hand over their relevant Electronic Dispatch
Information Logging (EDIL) to the HCC in Turlough Hill. This means whenever the
National Control Centre (NCC) sends a command to any one of these Hydro plants it
will always be passed through Turlough Hill first and sent on from here. In the event
of a minor fault occurring at any one of these hydro plants when no operator is
present which is during the night, Turlough Hill’s shift manager can login at home
using a lap top and deal with the fault from there. If a major fault occurs then the
controls are handed back to the local hydro plant immediately and the problem is to
be addressed by staff locally on site (ESB, 2008).

2.11 Pumped Hydro Storage demo (build & control)
This demonstration is based on the principal operation of Pumped Hydro Storage
and due to its small size it was not possible to replicate the same system as the one
being utilised at Turlough hill. The alternative method and the one chosen for this
project is too use a separate pump and turbine. The majority of Pumped Hydro
Storage plants around the world use a sophisticated level of control. This
demonstration will use a programmable logic controller (PLC) to operate all
necessary functions locally from a control panel with all the relevant inputs and
outputs. To further advance this project and make it more realistic supervisory control
and data acquisition (SCADA) was implemented to allow the whole process to be
controlled online by a laptop. SCADA provides a clear visual interface on a computer
screen showing the project operating and what stage it is at, whether it is consuming
or producing power and the level in the upper reservoir. The PLC will control the
process (see figure 9).
2.11.1 Controlling the Process
Figure 9: Project design & Equivalent CAD Drawing
As seen in figure 9, the Computer Aided Design (CAD) drawing shows how the
project is to be controlled. When the water is stored as potential energy in the upper
reservoir, meaning the process is in standby and is waiting for a signal to allow peak
time to commence. This signal is received from a limit switch located in the upper
reservoir whenever the water reaches a specific level. The PLC now tells the
solenoid valve to open and allow water to flow down the penstock to rotate a turbine
and drive a small D.C generator to produce enough power to supply an LED load.
This process continues until all the water is discharged into the lower reservoir. There
will then be a 15 second time delay now to simulate the passing of roughly 6 hours.
This time delay will be provided by a on delay timer located internally in the PLC.
When the timer operates and the limit switch in the lower reservoir is operated
suggesting there is water in the reservoir, then off peak time has commenced and the
pumping process can begin. The pump now activates until all the water has been
returned back to the upper reservoir again.

2.12 The DC generator
A DC generator is an electrical machine that converts mechanical energy into useful
electrical energy in the form of DC voltage and current by using magnetic induction.
The output power produced by the generator depends on the speed of rotation of the
shaft in revs per minute (rpm) and the electrical load that is connected to its output
terminals. A typical application of a DC generator could be a hydro power battery
charging system. The generator’s action is based on Faraday’s law of
electromagnetic induction, which states that an electromotive force (voltage) will be
induced in a conductor when the conductor passes through a varying magnetic field
(Alternative Energy Tutorials, 2013).
Figure 10: Construction of a DC generator
As seen in figure 10 the wire coil (or conductor) is positioned in such a way that when
it is rotated by a turbine for example. The wire coil will rotate and cut through the
magnetic flux which has been set up by the North and South Pole magnets. The
commutator rotates with the wire coil and delivers the voltage to the generator’s
stationary output terminals via two carbon brushes. All DC generators have two parts
called the stator and the rotor. The stator is the part of the generator that is fixed or
stationary and it is the part where the magnetic field is produced. The rotor is the
part of the generator that moves or rotates and is the part where the power
generating coil winding cuts the magnetic flux to produce a voltage (Alternative
Energy Tutorials, 2013).

2.13 The Pelton turbine runner
Figure 11: The Pelton turbine runner
The Pelton turbine is best suited for applications with high head and a low flow rate. It
is also a very efficient turbine as it extracts practically all of the energy from the water
jet delivered to it and has a very simple design. Water enters the penstock and builds
up pressure from a high head. This water then passes through a nozzle known as a
spear valve which converts the water under pressure into a high velocity jet. The
Pelton turbine’s runner is made up of a number of split buckets which are specifically
designed so that the high speed water jet hits them tangentially. Once water makes
contact with the split buckets, the notch in the middle of these buckets splits the jet of
water and deflects it back roughly at 180⁰. This is done to prevent the deflected water
interfering with the incoming water jet and allows all the water’s energy to go into
rotating the runner. The deflected water with zero energy left falls to the discharge
channel below. The Pelton turbine is a impulse turbine which means it is free to
rotate in air (Moloney, 2013).
2.14 Programmable Logic Controller
Programmable logic controllers (PLC’s) were designed to eliminate the need to
rewire and hard wire in different devices such as relays, timers and counters. A PLC
continuously monitors the state of its inputs and makes a decision based on the
implemented program wrote to it and will decide to turn on or off different output
devices. A PLC has two key advantages; one is it makes it easy to change or
replicate a process and the other is it is modular meaning it is possible to custom
build a PLC to suit a specific application. By using the GX-Works 2 software package
that is designated to Mitsubishi, it is possible to program and reprogram this PLC to
run a sequence of events such as the Pumped Hydro Storage demo rig. There are
two different types of programming languages that can be implemented to cater for
this project’s sequence; either sequential function chart (SFC) or ladder program.
Figure 12 Shows the Mitsubishi
FX2C PLC. This is the PLC that was
used to control the Pumped Hydro
Storage demo rig. The terminals
located on the top are the inputs
which are represented with an X0,
X1 etc. Located on the bottom are
the output terminals which are
represented using y0, y1 etc.
Figure 12: Mitsubishi FX2C PLC

Figure 13: FX-4AD Module
2.14.1 The PLC internal components
(mikroElektronika, 2003)
Figure 14: Basic layout of a PLC’s components
Figure 14 shows that a PC or laptop is required to write a program using the
necessary software and send it to the PLC. It is also useful to put the PC into monitor
mode to see that devices are switching low and high and that any timers or counters
that have been implemented are working properly (Mullen, 2014).
2.14.1.1 The central processing unit (CPU)
The CPU carries out the downloading and uploading of ladder programs and stores
and executes these various programs. The CPU is always in charge of interfacing
with other units in the PLC system such as the input-output circuitry and the memory.
The CPU is also in charge of monitoring in real time the operation of the uploaded
ladder program, it does this by doing checkups for errors. An error is easily detected
by an operator as an error LED will light on the front of the PLC (Mullen, 2014).
Figure 13 shows the Fx-4AD module. This
device attaches to the main PLC via a data
ribbon cable and its sole purpose is to
receive analog signals (0-10V) and convert
them into digital signals (1 or 0). For the
purpose of this project a level sensor
located in the upper tank will send a
variable voltage signal from 0-10V to
channel 2 on the FX-4AD module. It will
then display the level of the water in the
tank on the SCADA graphics screen.

2.14.1.2 Input unit
The input unit enables external input signals from field devices such as switches and
sensors to be hardwired to the PLC’s terminals to then be processed by the CPU.
Inputs can be digital or analog; a digital input is a switch i.e. open or closed (1 or 0)
and an analog input is variable i.e. from 0 to 1 (0-100%). An example of an analog
input would be to measure the variable level in a tank using a level sensor (Mullen,
2014).
2.14.1.3 Output unit
The output unit is connected to externally operated devices such as motors, pumps,
valves etc. Like an input, an output can also be digital i.e. on/off or analog which is 0
to 1. A digital output example would be an indicator lamp and an analog output would
be a motor that can run at various speeds (Mullen, 2014).
2.14.1.4 Power supply unit (PSU)
The PSU in a PLC is supplied directly from a 230V AC supply. The PSU then delivers
5V DC to its own internal electronics and supplies 24V DC to output devices such as
an LED indicator lamp on the control panel’s door. Alternatively, if field devices
require 24V DC or there are a lot of indicators to be supplied, then an external supply
can be used similar to the one chosen for this project (see figure 39)
(PLC System & Applications, 2014).
2.14.1.5 Opto-isolation in a PLC
Figure 15: Internal Opto-isolator
An Opto-isolator is an electronic component that transfers electrical signals from one
circuit to another using light. This is done to prevent high voltages (up to 10kV) that
might have superimposed themselves onto the cable connected to the PLC’s input
terminals causing damage to the CPU. All PLC inputs are isolated by Opto-isolators
to prevent chattering or other forms of electrical noise. The most common type of
Opto-isolator is a combination of an LED shining on to a photo transistor all enclosed
in the same package as seen in figure 15.There are three different types of outputs
that work on this same principal; the relay, the triac and the transistor. The relay is
the most common output and is used to switch DC and AC loads. The triac is used
for switching AC loads at voltages between 85-240V and can switch off fast. The
transistor is used in applications that require the fast switching of DC loads (PLC
System & Applications, 2014).

2.15 Supervisory Control and Data Acquisition (SCADA)
Figure 16: SCADA programming
SCADA is an industrial control system that is utilised in many applications with four
different types of distributed control systems. The power generation industry such as
Turlough hill uses the plant distributed control system (DCS). The HVAC industry
uses the direct digital control system (DDC). Water treatment plants which are
usually very large and spread out, use remote terminal unit based SCADA. The most
common type system and the one used in this project was the PLC based system
(See figure 16). A SCADA system allows total control and monitoring of a plant as
well as the gathering of data to be processed. Also there is direct communication
between the SCADA system and field devices such as level sensors and thermostats
that continually update the information presented on the graphics page. There are
many types of SCADA software and for this project Citect SCADA by Schneider
Electric was used (Inductive Automation, 2014).
Figure 17: 5 tasks of SCADA

There are five tasks that exist in every SCADA system and each one performs a
different process. As seen in figure 17 the display client manages all the data
necessary to be monitored by the operator and any control action that is requested
by that operator. The alarm server manages all the alarms by detecting digital alarm
points as well as comparing the values of analog control points with alarm thresholds.
The report server produces reports from the plants data and these reports can be
triggered by the operator, periodically or event triggered. The trend server collects
the data to be monitored over time. The input/output server is the interface between
the plant floor and the control/monitoring system (SCADA Communications &
Architecture, 2015).
2.16 PLC based system
(Wikipedia, 2015)
Figure 18: PLC based SCADA system
As seen in figure 18 the SCADA system reads the level in the tank from PLC2. PLC 2
will now close the control valve whenever the tank is empty. PLC 1 will now send a
signal to bring on the pump and the flow rate of the fluid being pumped around is
recorded by a flow meter also connected to PLC 1.

(Wikipedia, 2015)
Figure 19: SCADA graphics
Figure 19 shows how a typical SCADA graphics screen would display the devices
seen in figure 18. When building the graphic’s useful prompts to let an operator know
there is a faulty valve can be designed to change the valve’s colour to red. Also a
pump that is healthy and running can be given a colour green. Also in figure 19 the
tank has a slot cut away to expose the fluid inside. The light blue colour is the fluid
and the dark blue colour is the shadow caused by the empty space. It is always
advised to build a nice simple graphics screen with a neutral background and make
sure all the text is clearly visible.
2.17 The importance of variable tags in SCADA
Variable tags are references to memory addresses that are stored in the PLC’s
registers I/O devices. These references are in English and are set up at the start,
once the I/O is determined and before building the graphics begins (SCADA
Communications & Architecture, 2015).

3 Project finalised design
Originally this project was designed to be fully automated using both PLC and
SCADA control. However due to the limitations of having to work within a very small
head height and the pressure drop across the solenoid valve was extremely large.
Therefore the force of the water hitting the turbine wasn’t sufficient enough to turn it.
For this reason the solenoid valve was taken out and replaced with a manual gas
level valve. To let the operator know when to open or close this valve a green
indicating lamp was installed on the demo rig to prompt the operator to open when
the lamp is lit and close when the lamp isn’t lit. Initially it was planned to install 3
LEDs that could switch off one by one as the voltage generated decreased due to the
level in the upper reservoir decreasing. However it was decided insted to install three
different coloured LEDs in parallel that would all light at the same time to display the
generated power.
3.1 The method of the project
The demo rig always starts when the upper reservoir is full (Peak time generation).
Therefore by pressing the start button and if the upper limit switch located in the
upper reservoir is activated then manually open the lever valve to start the generation
to produce peak power. Now if the lower limit switch located in the lower reservoir is
activated, turn off the valve and start a 15 second time delay to simulate the change
over from peak to off-peak time. If this time change is complete then the pump turns
on to start the off-peak filling of the upper reservoir. When the upper limit switch is
then reactivated the sequence will restart all over again. This can be seen outlined
clearly in the flow chart below in section 3.1.1.

3.1.1 Flow chart of finalised design
Start Button
Is upper limit
switch
activated?
Is lower limit
switch
activated?
Is the time
delay over?
Open lever valve
Turn off valve and start the
delay on timer
Turn on the pump
Yes
No

3.2 Inputs & outputs list (I/O list)
This is a list that shows the devices used with addresses and a brief description of
what each device does.
Table 1: I/O list for the different devices
Device Address Tag
Name
Action
Start P.B N/O X0 S1 Process starts running (control panel)
Stop P.B N/C X1 S2 Process stops running (control panel)
Start P.B SCADA M16 S1 Process starts running (SCADA)
Stop P.B SCADA M15 S2 Process stops running (SCADA)
Upper limit switch
N/O
X2 B1 Indicates upper tank is full
Lower limit switch
N/O
X3 B2 Indicates lower tank is full
Lever valve Y1 H1 Releases water to start generating
Pump Y2 H2 Pumps water back up to upper tank
Change over
Indicator lamp
Y5 L1 Simulates time delay from peak to off
peak-time
Off-Peak time
Indicator lamp
Y6 L2 Off peak time has begun start pumping
water up
Peak time
Indicator lamp
Y7 L3 Peak time has begun start generating
power

3.3 The PLC ladder program
The following ladder diagram was drawn up in GX-Works 2.
The first branch consists of three elements in parallel which is the start button on the
control panel (PB Start), the start button on the SCADA screen (SCADA Start) and
the hold on contact from the memory relay. The next elements are the stop button on
the control panel (PB stop) and the stop button on the SCADA screen. If either start
button is activated or none of the stop buttons are activated, then the memory relay
(M8) turns on with a hold on contact.
When the memory relay (m8) is high and both the lower limit switch and pump are
not activated then open the valve and turn on the red peak time indicator lamp.

Again, with M8 high and the lower limit switch has been activated then turn on the
green time delay lamp and start an off-delay timer for 15 seconds. Once timer has
been timed out, turn off the green indicating lamp.
When timer is high and neither the upper limit switch nor the valve is open and M8 is
high, then turn on the pump and the orange off-peak indicator lamp. The pump also
provides a hold on to keep the pumping process going.

This is the code required to allow the PLC to read the variable analog input from the
FX-4AD module. The first part is a cross check for good practice to ensure the
analog module is being read correctly. When M8000 (always 1 when PLC in run
mode) is high, function block K0 is read from BFM K30 in the same function block
and the value is stored in data register D4. This is then compared to check that the
block is an FX-4AD and if so, M1 is turned on. The input channel 2 (CH2) is used in
this project and is selected by writing H3300 to BFM K0 of the FX-4AD. The number
of averaged samples for CH2 is set to 4, by writing 4 to BFM K1 and K2. The
operational status of the FX-4AD is read from BFM K29 and if there are no errors the
value is read from K6, converted into the base units and stored in data register D20.
The value in D20 will continuously vary as the level in the upper tank changes. It is
this value that is used to show the position of the water in the upper reservoir.

3.4 The selected components
There were 5 key devices located on the movable demo rig (See figures 19-23
below). These devices used where small in size but were selected specifically to
operate at the extra low voltage band (2-24VDC). Therefore a 24V power supply was
used to supply the devices on the demo rig itself and the PLC’s own 24V power
supply supplied the lamp indicators on the front door of the panel.
(Ebay, 2014)
Figure 20: The submersible water pump
Figure 21: Automatic valve Vs manual valve
The first design included the solenoid valve, but with the reduced water pressure it
had to be changed for a manual valve. It would have been preferred to use the
solenoid valve but with its design it just didn’t suit this project. The gas valve released
the water at a greater rate and therefore was selected an installed with the down side
of having to open it manually.
Figure 20 shows the small 24V DC
submersible pump that is typically used in
transporting diesel to fill up a car. This
pump has a flow rate of 30L/min (see
appendix E). However for this application it
took over two minutes to pump up 36L
because the pump had to overcome a head
height of 1.2M and a 90 degree bend in the
pipe.

Figure 22: The Milone eTape level sensor
This sensor was vertically installed in the upper reservoir to measure the level. The
water must be allowed to touch both sides of the sensor to allow compression by the
hydrostatic pressure that’s associated with water. This hydrostatic pressure changes
the level sensors resistance which corresponds with the distance from the top of the
sensor to surface of the water. The resistance change is inversely proportional to the
level of the water. The level sensor required a supply of 10V across its 2 inner
terminals and therefore the voltage divider rule was applied to find the correct resistor
(Rref) to put in series to drop the voltage from 24V down to 10V (see figure 22) (see
appendix D).
 Level sensor (R2) = 2200Ω
 Reference resistor (R1) =?
 Supply voltage (Vs) = 24V
 Voltage at the analog to digital converter (VADC) = 10V
VADC = * Vs = 10V= * 24V
R1 = = 3080Ω
Therefore a 3300Ω resistor was sufficient.

Figure 23: The DC generator
Figure 24: The 3 LED’s supplied by generated power
The main objective set out at the beginning of this project was to supply a load from a
renewable source. This was achieved by connecting 3 different coloured LEDs in
parallel with each other and connecting them across the generator’s output directly
with no protective resistor required as seen in figure 24.
The small DC generator as seen in figure 23
was one of the most crucial parts in ensuring
the success of this project. It was the output
power of the generator that would make the
decision on the size and type of load that could
be supplied. The generator could supply 2.5V at
a current of 55mA to give an output power
supply of 0.14 Watts. This was a tiny amount of
power but was sufficient enough to light 3 LED’s
for demonstration purposes.

3.5 PLC wiring diagram
Figure 25: PLC wiring layout
Figure 25 shows the layout of the PLC which was drawn up in Auto CAD Electrical.
Located across the top are the inputs and on the bottom are the outputs. Refer to
table 1 for the complete I/O list. A 24V power supplied was used to supply the pump
and the valve (valve indicator lamp) on the demonstration. An emergency stop button
was added to the circuit for safety and once activated; all the outputs are isolated
from supply.
Figure 26: The FX-4AD wiring diagram
Figure 26 shows the FX-4AD module. The
level sensor was connected directly across
both the V+ and Com terminals. A 0V to 10V
signal is then read on channel 2 via the level
sensor and changed to a bit format that is
read by the PLC. The dial was moved to
channel 2 and when the upper reservoir was
full the gain button was pressed and the
corresponding bit value recorded. When the
upper reservoir was empty the offset button
was pressed and that bit value was
recorded. The dial was they moved back to
ready for normal operation. The bit values
where then used in SCADA for the variable
tags (integer) to show the changing level of
the upper reservoir.

3.6 Material required & costing
This was a very important part of the project and after the initial design was agreed
on, a materials list was drawn up to be requested from the college. This was all done
in late December at the very start to avoid delay on parts later on that might have had
an effect on getting the project completed before the deadline. Sourcing these
materials was a good chance to communicate with wholesalers in various types of
industries such as electrical, mechanical and plumbing in order to get quotations for
various parts. Once all quotations were gathered they then had to be signed off by
the supervisor and sent in to the college to try and get the required funding
necessary to purchase these parts. To try and keep within a budget as much as
possible some of the technicians in the college were asked to see if they had any
parts available from previous projects. This worked well as only some parts of this
project had to be sourced from outside the college which helped reduce the cost and
meant work could start right away. A full list of these items can be seen in table 2
below with some quotations in the appendix.
Table 2: Price list for components used
Item Use Source Price (€)
Metal The frame Miko Metals 135
Pump Pumping water Ebay 10
Solenoid valve Releasing water RS Radionics 68
Gas valve Replacing solenoid valve Woodies DIY 10
Water butt 2 Reservoirs Shannon Airport 10
Piping and fittings Distribute water Heat Merchants 40
DC Motor Generator Home 0
Turbine Spinning the generator Amazon 8
Limit switches Switching on/off pump College 0
Level sensor Measuring tank level College 30
Control panel Controlling the project College 0
Control panel’s parts Operating the demo College 0

4 The build process
After carrying out some detailed research to gain knowledge about the background of
Pumped Hydro Storage, it was now time to put a clear outlined plan into effect by
building a movable demonstration rig.
Figure 27: Making the upper & lower reservoir
4.1 Creating the upper & lower reservoirs
After a lot of searching the internet for tanks that would be a suitable choice for the
reservoirs at a reasonable price, it was discovered that the best fit was to buy a 55
gallon water butt that was sealed at both ends and cut it in half. This was purchased
for 10 euro, which saved a portion of the budget that could be used else were in the
project. The tanks were cut in half using a grinder which left a nice smooth finish (see
figure 27).
Figure 28: Tanks fitted
The tank’s dimensions were 23 inches wide by 35
inches high. Therefore cutting the tank in half would
in theory allow a storage capacity of 22.5 gallons or
85 litres of water. In a rough estimate done previous
a tank with a capacity of 60 litres would have been
enough to simulate power generation for 1 minute
(1L/S flow rate). The completed demonstration is
intended to be stored away for later use in future
years; therefore it required a way of draining the
water down after use. As seen in figure 27 there are
2 threaded bungs at the bottom of the tank that can
be opened to allow water to escape out in a short
period of time. Therefore for this reason that
particular tank was chosen for the lower reservoir
and placed at the bottom. Figure 28 shows the
completed frame with the tanks fitted in position.

4.2 The movable frame
This next part of the build was to construct a solid and sturdy movable frame that
would allow the demonstration to carry all the weight from the water residing in the
upper tank. It had a specific height restriction so that it could fit through an average
door frame. Choosing the frames height however was a trade-off which meant that
for safety and for practicality of demonstrating the head height was kept to a
minimum, which therefore meant that power generation was reduced.
4.2.1 Constructing the frame
Figure 28: Assembling the frame
As seen in figure 28, the frame was assembled from 25mm aluminium box which was
purchased from Mico Metals in Co. Cork (see appendix B). The wheels for the project
where salvaged from a previous project that the college had in storage. The frame
had to be made to a specific size to allow for the diameter of the rounded tank to fit
into place. Once all pieces were cut and filed, it was then a matter of attaching the
plastic inserts and slotting all the pieces in to their correct positions. To prevent any
dents or damage to the frame a mallet was the best tool for assembling. The
brackets used to support both tanks in position were also fitted at this stage using a
cordless drill and a ratchet set.

4.3 Attaching the limit switches
The limit switches used were basic extra low voltage 24V normally open contacts.
When the water reaches the required level the limit switches contact changes state
and closes. This action will now input a signal to the PLC to take a course of action. If
the upper limit switch activates the pump turns off as the required level has been
reached. If the lower limit switch has been activated then the valve shuts off as the
correct volume of water has been released from the upper reservoir. Neither of these
limit switches will be operated at the same time.
Figure 27: Fitted the limit switches
As also mentioned in section 4.1, the level of the water is a key factor in the
demonstration with regards to simulation time. Roughly estimating for a flow rate of
1L/S then the tank needs a storage capacity of 60 litres so it can deliver water to the
turbine for 1 minute (60 seconds). Also to allow the demonstration to be moved
around without spilling any water the limit switches were fitted at 12 inches in height
to achieve the 60 litres but also give a clearance of 7.5 inches from the surface of the
water to the rim of the tank (see figure 27).
Half tank = 85 litres @ a height of 17.5 inches
Therefore for 1 inch in height = = 4.86L/Inch
Height of 60 litres = = 12.34 Inches
4.3.1 The actual volume of water in the upper tank
A revised plan was done on the upper reservoir because instead of an average flow
rate of 1L/S as was initially estimated the best that could be gained from the rig was
0.3L/S. Therefore the upper limit switch was moved down from 12.34 inches to 7.5
inches which allowed 36L to reside in the upper reservoir.

4.4 The plumbing phase
There was a certain amount of plumbing required for this project. Once the tanks
were fitted in place the plumbing phase could begin.
Figure 28: Connecting the valve & the pump
As seen in figure 28, the first part was to bore a hole at the bottom of the tank. A
stepped cone cutter was used with a lot of care to ensure the hole was not drilled out
too big for the fitting. The copper inserts were then installed for the valve and the
pump was attached to a flexible pipe and held in position using a jubilee clip.
Figure 29: Bending & offsetting the pipe work
Figure 30: Testing the pump
Figure 29 shows how the copper pipe was bent. This
was the pipe that was required to return the water back
to the upper reservoir. At one end a 90 degree swan
neck bend was formed and at the opposite end there
was a 30 degree off set. The offset allowed the pipe to
be placed inside the lower reservoir so the flexible pipe
could be attached to it. This was done in case the
flexible pipe became detached during operation,
causing a leak. Figure 30 shows a quick test carried out
on the pump before it was fitted and it emptied a basin
of water in 3 seconds proving it was more that capable
for the job of pumping up 1.2M.

4.4.1 Editing key areas of plumbing phase
The original plumbing phase had to be edited due to the solenoid valve failing to
allow the water through at a flow rate that was sufficient enough to turn the turbines
runner (see appendix C).
Figure 31: Making the necessary changes to the penstock
As seen in figure 31, the first change that was made was to increase the size of the
copper pipe from ½ inch to ¾ inch. Then the solenoid valve was taking out and
replaced with a gas lever valve. The lever valve unfortunately had to be manually
operated but had the advantage of allowing the flow rate to be increased from
negligible to 0.3 litres per second. Also as an added improvement an end nozzle
reducer was fitted to increase the velocity of the water hitting the turbines runner.
Figure 32: Fitting a shield over the turbine
With the increase in velocity helped by the nozzle, the water was then reflecting back
of the runner and was splashing out on to the floor which caused a slipping hazard.
Therefore as seen in figure 32 a Perspex shield angled a 45 degrees was attached to
prevent this from happening.

4.5 Constructing the turbine unit
This was undoubtedly the most ambitious and challenging part of the project. The
size restriction on this demonstration meant it was difficult to find a suitable runner
that could be attached to the generator to create power. Therefore after careful
consideration it was decided that an edited homemade version of a Pelton turbine
was the most suitable for a generator of this size.
Figure 33: Making the runner
The runner was created using 2 fan blades as seen in figure 33. These fan blades
are usually attached to the shaft of a 3 phase motor for cooling purposes. Although
both these blades were purchased on line from the same manufacturer the slots in
the centre bore-hole of each one did not match up exactly with each other. After
some delicate drilling and filing this problem was resolved and the blades were super
glued together to make the complete runner. The runner created was more like a
paddle wheel and does not resemble a regular Pelton turbine blade that has a
special curve like design as seen in figure 11.
4.5.1 Testing the generator and attaching all necessary parts
Figure 34: Attaching all the turbines components

To find the correct DC generator to use was a matter of trial an error. As seen in
figure 34, the picture on the left shows a test carried out using an 18 V cordless drill
in first gear to mimic the speed that the turbine’s runner would be rotating at. The DC
generator was normally used as a DC motor that changed electrical energy into
mechanical energy. If that process is reversed by attaching a runner to the motors
shaft to spin it in reverse, then mechanical energy will be converted into electrical
energy.
There was 2 motors tested; the first motor selected had a rated speed of 500rpm and
was normally used to open and close window blinds, meaning it required more torque
at less speed. This motor when run in reverse by the drill only delivered 0.5V,
meaning it was not suitable and was left to one side. The next DC motor was
removed from a toy car and had a rated speed of 2000rpm with very little torque,
which became clear as the shaft was very easily turned, even by hand. When put to
the same test using the drill, this motor in reverse achieved 6V and therefore was the
most suitable motor to use as a generator for the project.
In figure 34, the picture in the centre shows all the components that were required in
attaching the runner to the DC generator. The extension piece required to connect
the generator shaft to the turbine’s runner was machined using one of the lathes in
the college. This rotation was made possible using a bearing which was housed in a
solid aluminium bar and can also be seen in the centre picture above.
Figure 35: Turbine in position
The turbine and generator was
then attached to a bracket which
was also made from aluminium as
seen in figure 35. The entire unit
was placed in the demonstration
and ready for the real test using
water. Aluminium was the metal
mainly used as it is much lighter
than mild steel.

4.6 Electrical Phase
Before the wiring process could begin it was important to have a clear understanding
of how many inputs and outputs are required in the project, their voltages and how
they are to be wired. Therefore the first step was to draw up an electrical plan in Auto
CAD electrical (See figure 25).
4.6.1 Wiring the control panel & PLC
Once the control panel and all the necessary components were sourced it was time
to start putting everything into place. For the size of the panel 2 rows was all that
could be used.
Figure 36: Arranging the control panel's components
The first step was to install the din rail and cable trunking. Then for best fit the 24V
PSU, PLC and the FX-4AD module were installed on the top row. On the second row
an isolator, control fuse and the required amount of terminal blocks were fitted. The
last part before the wiring could start was to drill out the holes on the control panel’s
door for the 2 push buttons, the emergency stop button and the 3 indicator lamps
shown in figure 36.
Figure 37: Terminating the inputs & outputs
As seen in figure 37, for best practice and to allow easy traceability each terminal
block was labelled with its correct I/O tag. The cable used was single core 0.75mm2
.
The red cable was used for 24V and the black cable was used for 0V. The end of
each cable was paired off using a snips and a boot laced Ferrell was crimped to
allow a good safe termination.

Figure 38: Control panel complete
The control panel could now be fixed in its permanent position to make it easier to
work on and for displaying when it came to demonstration time at the end.
4.6.2 Wiring the demo rig’s devices
Figure 39: Attaching the trunking & junction box
On the demonstration’s frame as seen in figure 39, each frame was 25mm wide,
which meant 25mm PVC trunking fitted perfectly and provided adequate protection
for the cables brought out to each device. The original plan was to mount the control
panel directly to the movable frame which would have caused an unbalance due to
excess weight on one side. Therefore it was just fixed to the wall in the work shop.
Figure 38 shows the control panel
completely wired with the PLC’s
inputs and outputs and the analog
module’s inputs all connected to
their designated terminal blocks. The
next stage was to start wiring from
the control panels terminal blocks to
the inputs and outputs located on
the demo rig.

Figure 40 Termination box
Figure 41: Soldering the connection points
In figure 41, the picture on the left shows a female serial point before it was soldered.
The picture in the middle shows the wires being soldered in to each of the different
slots. This was very tedious, precise work and it was found that attaching the male
lead to hold things in place made it easier to get a good soldered termination. The
picture on the right shows the finished connection. All that had to be done now was
attach another female serial point on the control panel and make sure the numbers
on both of these points correspond with each other. This meant that the demo rig
was now portable, as the only link between the rig and control panel was through a
detachable serial cable.
An 8X6 inch junction box was fixed to the corner
of the frame. A small piece of din rail was then
fitted to the inside of the box to allow the terminal
blocks to fit securely in place. A slot was then cut
out of the 25mm trunking that ran across the top
of the box to allow cables inside to be terminated.
As seen in figure 40 a female serial connection
point was also drilled out and fitted to allow
connection between the junction box and the
control panel.

4.7 Installing the serial to USB PLC software
With the demonstration now wired down as far as the level sensor and LEDs it was
now time to upload the necessary software that would allow communication between
the PLC and the laptop. This would also prove very useful in testing what was done
so far and in calibrating the level sensor later on.
Figure 42: Downloading the brain box serial to USB software
As seen in figure 42 the software used was the Brain box serial to USB. The first part
was to install the software on the lap using a CD. Then when prompted insert the
USB to serial converter and once recognised by the laptop, the CD could be
removed. The ladder program could now be written and exported to the PLC through
Com 4 on the lab tops control panel.
4.8 Connecting the level sensor
Before the level sensor could be attached to the FX-4AD, some electronic circuitry
had to be put in place.
Figure 43: Soldering components to a Vero board
The middle picture in figure 43 shows a 3300Ω resistor in series with a test resistor.
The test resistor was to simulate a resistance value typical to the level sensor. Once
everything was soldered in position the test resistor was removed and replaced by 2
leads that were brought up to the level sensor in the upper reservoir. As seen in the
picture on the right, the same leads that were connected across the two inner
terminals of the level sensor where also the leads that would isplay the variable
voltage value (0-10V) across the FX-4AD converter.

Figure 44: Checking the level sensor works before installation
By simply half submerging the level sensor in water it could be seen clearly that the
voltage dropped from 10V to 6V as seen on the volt meter in figure 47. This was
consistent with the spec sheet (See appendix D) and therefore the level sensor was
installed in the upper reservoir.
Figure 45: Securing the level sensor
Initially as seen in figure 45 the picture on the left shows how the level sensor was
set up against a strip of plastic PVC trunking to allow the water to make contact with
both sides of the level sensor. However this did not work for two reasons. Firstly the
sensor was touching the trunking which gave a false reading of the depth of the
water and secondly the water being delivered back up by the pump caused a large
disturbance on the surface of the water which contributed to an unstable reading.
Therefore as seen in the picture on the right it was decided to install the level sensor
inside a waste pipe which had holes drilled in its sides to keep the surface
fluctuations to a minimum.

4.9 Supplying the LED load
The most rewarding part of the project was to see if a useable power output could be
delivered by the generator to supply a small load that would symbolise a consumer’s
power requirement. This was achieved by using 3 standard LED’s that switch on
between 1.9V and 2.1V, at a current of 20mA.
Figure 46: Checking to see if it is best to wire LED’s in parallel or series
Before the 3 LED’s were fitted in their housing on the demo rig it was important to
figure out the best way to wire them, either in series or parallel. As seen in figure 46,
wiring the LED’s in series meant only one shone brightly, whereas in parallel they all
lit but one was dimmer than the other two. Therefore it was chosen to wire them in
parallel.
4.10 The complete build design
Figure 47: The completion of the build
Figure 47 shows the completed project and control panel mounted upright on the
wall. Everything was now in position, working and ready for demonstrating.

4.11 Implementing Citect SCADA
When using Citect SCADA to monitor and control this demo rig it was very important
to set up the project properly from the very beginning.
Figure 48: Setting up the users & roles in SCADA
This part was setting up the role of the user (Engineer) and choosing which area they
can access (global privileges). It is also a requirement to set up a password at this
stage as seen in figure 48.
Figure 49: Setting up clusters and servers
In this part a cluster (project) was set up which required a name “hydro” as seen in
figure 49. Included in this cluster was three servers called alarm, report and trend
(see figure 17). It is important not to include the I/O server at this stage.

Figure 50: Setting up the I/O device
To set up the I/O device navigation must be made through the set up wizard first, to
choose the stand alone option. Then under communications, using the express
wizard the option for external I/O device was selected to allow communication via the
PC as seen in figure 50.
Figure 51: Example of a variable tag (Integer)
This was a very important step because it was assigning specific names to variable
tags in the project for later use when designing the graphic’s page. The tag for the
level sensor (analog) as seen in figure 51 was different to all the other tags which are
digital. The raw zero scale value represents the bits read from the PLC in monitor
mode via the FX-AD4 and corresponds to an empty tank (Eng Zero Scale = 0 %).
The raw full scale value was also read at -320 bits and corresponds to a full tank
(Eng Full Scale 100%). After the 10 records were completed, it was time to pack and
compile.

Figure 52: Building the graphics page
This was the part where each component was addressed with a variable tag selected
earlier in (see figure 51). It is always good practice to select the tag from the drop
down menu instead of typing it in because any change i.e. a change of spelling would
result in the tag required not being detected. Figure 52 also shows the part where the
animated text and different colours for devices (off/on, grey/green) are set up.
Figure 53: The completed graphics page
Figure 53 shows the completed graphics page showing the demo rig and control
panel. This page was kept as close to the real project as possible. The level in the
upper reservoir varies as the level in the real rig varies. The demo rig can be
controlled and monitored using this page. Login can also be done here.

4.12 Skills developed & challenges
When completing the building of this project there where many aspects that provided
many challenges and trade-offs to make things work. There were many skills
developed that supported the theory learned during the course of the year. For
example, the PLC and SCADA programming was extremely beneficial to see how
they can both be applied to a real application. Using the voltage divider law to find
the correct value of a resistor and then installing that resistor to make the level
sensor work was also nice to see in a real application. How the analog to digital
converter operates was a difficult part to understand from reading but when seeing it
in real life and to program and manipulate it to do a certain task made the operation
much clearer to understand. A lot of perseverance was required for this project
because of how ambitious it was to implement on such a small scale. The minute
meetings (see appendix G) were a vital part of learning because it gave a chance to
express any concerns and seek advice from the supervisor.
The learning achieved in SCADA was very beneficial in regards to the plant
information systems module. Extra pages where set up in SCADA such as an alarm
page, overview page, trend page and a hardware page. Also for added security
anyone wanting to run or change things to the graphics in this project had to login
with a user name and password and depending on the role name provided only
certain parameters were available to be changed (see appendix F).

5 Project testing
This was the part of the project that tested and analysed everything that was
undertaken so far. The main aim of this project was to deliver generated power from
a renewable source. Through a series of tests it was proved that a very small voltage
and current was generated.
Figure 54: Voltage and current output from the generator
As seen in figure 54 the voltage output from the generator was 2.5V with a current of
55mA. Therefore the power produced was 0.14W.
Power (W) = Voltage (V) * Current (A)
2.5V * 0.055A = 0.14W

5.1 Determining the average flow rate
Figure 55: Measuring the average flow rate
The very first step as seen in figure 55 was to fill the lower reservoir until the lower
limit switch was activated. There was enough water now in the lower reservoir not to
impede the turbines runner from spinning but also enough water in the lower
reservoir to keep the pump from running dry. This was because the upper limit switch
in the upper reservoir always operates before this can happen. It is this volume of
water that will determine the flow rate. The middle picture shows a water drum with a
maximum known volume of 10 litres of water with a minimum of 1 litre. The water
drum was placed under the pipe in the upper reservoir with all the water residing in
the lower reservoir.
The pump was then turned on until the water drum was filled with 10 litres of water
and emptied into the upper reservoir with the valve held shut. This process was
repeated until the correct volume of water was extracted from the lower to the upper
reservoir. It took 3.6 drums which meant a volume of 36 litres was recycled between
these reservoirs. The valve was then opened to release the water back down and
using a stop watch it was found that it took 2 minutes (120 seconds) to empty the 36
litres. Therefore this meant that every second 0.3 litres of water was leaving the tank
and this could be used as the average flow rate.
5.1.1 Generating efficiency
P = ƞ*Q*h*g
 Flow rate (Q) = 0.3L/s = 0.3Kg/s
 Output power (POUT) = 0.14W
 Head height (h) = 0.9M
 Acceleration due to gravity (g) = 9.81M/S2
 Efficiency ( ) =?
ȠGENERATING = = = 5.3% efficient

5.1.2 Energy capacity storage
Energy capacity storage is the amount of potential energy stored in the upper
reservoir, which is set by the mass of the water stored there.
E = ƞGEN*M*h*g
 Energy capacity (E) =?
 Generator efficiency (ƞGEN) = 5.3%
 Mass of water (M) = 36Kg
 Head height (h)
 Acceleration due to gravity (g) = 9.81 M/S2
E = 0.053*36kg*0.9M*9.81 M/S2
= 16.81Joules
5.1.3 Pumping efficiency
This efficiency is due to the energy lost in pumping the water back up.
ȠPUMPING = = * 100 = 0.4%
5.1.4 Overall efficiency of the project
This is the efficiency of the entire project and is the product of both the pumping and
generating efficiencies.
ȠOVERALL = ȠGENERATING * ȠPUMPING
ȠOVERALL = 5.3% * 0.4% = 2.12%
This is a really poor efficiency and in no way shape or form is directly related to the
efficiency of a typical Pumped Hydro Storage plant that could have efficiency greater
that 80%. However it was very useful to have this demonstration to allow these
calculations to be performed in such a practical way.

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