Hybrid Pumped Hydro Storage Energy Solutions towards Wind ...
Transcript of Hybrid Pumped Hydro Storage Energy Solutions towards Wind ...
Hybrid Pumped Hydro Storage
Energy Solutions towards Wind
and PV Integration
Prof Helena M. Ramos
INTRODUCTION
The growing energy crisis and the excessive consumption of resources are raising concerns about
finding new alternative energy sources, enabling new production methods and/or making existing
ones more efficient
Methane (CH4-waste sector), nitrous
oxide (N2O-agricultural sector) and
halogenated compounds, namely
chlorofluorocarbons,
hydrofluorocarbons and
perfluorocarbons (F gases), in
addition to carbon dioxide (CO2-
energy sector) are the main causes
of increasing environmental
awareness and increased levels of
greenhouse gases.
Compared to 1990, the European Union intends to reduce its internal emissions by 80 % by 2050.
Regarding this, it appears that a reduction in CO2 emissions of around 70 % between 1990 and
2050 is likely to occur in the energy and industrial processes sector
INTRODUCTION
At the beginning of this century, Europe made huge investments in renewable energy. Advanced
EEA data (EEA 2017) show that, on average, the share of renewable sources in final energy
consumption has increased by 6.7 % per year since 2005 (slightly slowed in the last 2 years)
The objective of the EU is to
achieve the target of 20% use
of renewable energy in 2020.
The proportion is estimated to
be 17 % in 2016, so it is within
the plan
INTRODUCTIONSweden is undoubtedly the most
prominent of the 28 Member
States (with a 54 % share),
followed by Finland and Latvia (40
and 38 %). Portugal is ranked
seventh (28 %), contributing
positively to the European average
Portugal is one of the 9 EU
countries with significant
greenhouse gas emission
reductions (more than 10% from
2005 to 2015)
β Nowadays we seek to rationalize water and energy consumption and produce non-
pollutant energy by implementing clean, hybrid, cost-effective solutions based on
renewable energy sources to meet the environmental issues of sustainability (e.g.
minimization of CO2 emissions).
β Moreover, many countries usually import most of the energy they need, suffering the
consequences of the increased consumption, on the price and on the availability
fossil resources, as well as they have to face the issue of greenhouse gases.
β Accordingly, it is necessary to develop integrated studies on water and energy
(WATER β ENERGY nexus) in order to implement innovative clean solutions through
effective strategic analyses.
β Contemporary societies are characterized by an extreme dependence on water and
energy.
Main objectives
β Water consumption has been growing at more than twice the rate of the population growth in the last century.It is estimated that the global population of nine billion people are consuming about 60% of available freshwater WWAP (2018). Water extraction are expected to increase by 50% by 2025 in developing countries, and 18% in developed countries.
β In 2025, 1 800 million of people will be living in countries or regions with absolute water scarcity, and two thirds of the world population might be under conditions of water shortage.
In 2010
β New paradigm: the increased consumption has been responded with
increased supply, which has led in some countries, unsustainable
levels of water and energy consumption, production of pollutants with
the well known reflex to the climate change problem.
Hydropower and Pumped storage
have a huge advantage of start-up and energy injection in the grid rapidly,
lesser than three minutes, while thermal plants require a minimum of
eight hours to start generating energy, being highly polluting
ENERGY PRODUCTION FROM RENEWABLE SOURCES
Regarding the production of energy from
renewable sources, Portugal exhibits enormous
potential: hydro, wind, bioenergy, solar, tides
and waves
At present, the first four are the most widely
used and contribute the most to the vast
majority of renewable energy produced
Solar
Bioenergy
Wind
Hydro
Fossil Cogeneration
Natural Gas
Coal
The use of RES
Wind and solar supporting pumped
hydropower storage solutions
New cases of Pumped Hydropower Storage in Portugal
However, they still lack some competitiveness because of their intermittency, and therefore there is
a need to resort to fossil energies
Despite the gradual increase in electricity production from renewable sources, it is a fact that 2017
brought a setback as it was marked by the presence of extreme drought conditions, reflected in
hydroelectric productivity, which decreased by just over 1/3 of 2016 production
As a result, only 44.3% (22 956 GWh) of mainland Portugal's total electricity consumption (51 839
GWh) comes from renewable sources
In the opposite direction was the production of fossil source, which supplemented with 31 567 GWh.
This reversal resulted in an increase of more than 25% in carbon dioxide emissions compared to the
previous year, which amounted to approximately 15 x 10^6 tonnes of CO22
ENERGY PRODUCTION FROM RENEWABLE SOURCES
In any case, the variation in the production of renewable energy throughout the year can be
analyzed, i.e., although it is always different during homologous periods, it presents the same
annual patterns
Hydropower production was the
highest in the first quarter, and
in the summer months it was
three to four times lower. Wind
energy production is more
regular, but it also has the
same pattern as hydro (with
higher production in winter and
lower production in summer)
ENERGY PRODUCTION FROM RENEWABLE SOURCES
Since wind speed and water
inflows have average year-
round variations with a high
correlation, production is
expected to be simultaneous
In contrast, in the summer
months, solar energy
production is at its peak
In this way, it is possible to
complement the production of
energy throughout the year with
the other two sources
ENERGY PRODUCTION FROM RENEWABLE SOURCES
There is a correlation between energy consumption and production from renewable sources, the
higher the output. The relationship between the energy source and the selling price of electricity
also exists in terms of costs, i.e. the greater the representativeness of the renewable energy source,
the lower the market price
A certain increase
in energy
consumption could
be a sign of a
recovery in the
economy
ENERGY PRODUCTION FROM RENEWABLE SOURCES
Correlation of the market price and the
renewable production
DemandRenewable energy production Market price
Specific emissions of the electric sector in Portugal 1999-2030
The penetration of Renewable
Energy Sources (RES) in existing
power systems, namely wind,
showed a considerable growth
since 2000, not only in terms of
installed capacity, but also the
total electricity share
ENERGY PRODUCTION FROM RENEWABLE SOURCES
In small and isolated systems,
without interconnections, the impact
of RES tends to be higher than in
interconnected power systems,
where the RES variability effect can
be smoothed
ENERGY PRODUCTION FROM RENEWABLE SOURCES
Due to the growing awareness
about environment, climate
changes, pollution and waste
footprint, clean and renewable
sources of energy are being
encouraged and used globally.
ENERGY PRODUCTION FROM RENEWABLE SOURCES
With these growing trends of using
intermittent renewable sources of
energy, there will be a greater need
to make flexible the modern energy
production and distribution
systems
For instances a rate of 56 % incorporation of renewable energy sources (RES) into electricity
generation was recorded in 2019, equivalent to 27.3 TWh of electricity generation, out of a total of
48.8 TWh in Portugal. The remaining 44 % represented fossil fuels, corresponding to 21.4 TWh
In electricity generation, there was a
3.1% increase in renewables
representation compared to 2018.
In fact, hydroelectric generation was
reduced due to a shortage of water
resources during the summer, which
was filled during the winter
ENERGY PRODUCTION FROM RENEWABLE SOURCES
The use of self-consumption devices (e.g. photovoltaic panels) is a factor in the development of a
number of clean technologies and the promotion of more active consumer behaviour, which is
also increasingly facilitated by the design of more efficient control appliances and systems
ENERGY PRODUCTION FROM RENEWABLE SOURCES
Although renewable sources of energy are practically inexhaustible and environmentally friendly, as
they depend on atmospheric conditions, they are also unpredictable and have variable availability
This often creates an imbalance
between energy demand and supply, but
the full potential of the use of renewable
energy can not be eliminated. This
imbalance may occur when there is a
shortage of energy sources, as is in
times of drought, when dams are losing
their capacity due to a lack of rainfall
and, consequently, without sufficient
storage for hydropower generation
BALANCE BETWEEN ENERGY SUPPLY AND DEMAND
Visualization of 30 days of superimposed power demand time series data (red), wind energy generation
data (blue), and solar insolation data (yellow). Average values are in color-highlighted black lines
But the opposite may also be the case, i.e., there are times when supply is greater than demand, so
all that unused excess energy is either exported or wasted
BALANCE BETWEEN ENERGY SUPPLY AND DEMAND
Three possible strategies to ensure a balance between energy supply and demand are as follows:
1) Limiting the generation of
renewable energy sources (avoiding
the waste of these resources) and
increasing the generation of
thermoelectric power. This solution is
not sustainable and does not fulfill the
objective of making energy production
more efficient
BALANCE BETWEEN ENERGY SUPPLY AND DEMAND
3) Store the surplus of electricity
produced to be used later in higher
consumption periods. This is the most
effective way to control the variation in
supply / demand.
BALANCE BETWEEN ENERGY SUPPLY AND DEMAND
2) Exporting the surplus to
neighboring countries is a solution
that depends on the external
absorption capacity, although it has
already been done;
incompatibility
PUMPED HYDRO STORAGE systems (PHS)
The introduction of PHS in the
Madeira Island (Socorridos)
Portugal, or in Canary Islands,
Spain, concludes that this type of
energy storage contributes
positively to the increase in wind
energy penetration
Pumped Hydro Storage systems (PHS) are one of the well-known and studied types of energy
storage that can be introduced with success in small/large and/or isolated systems, showing a
positive outcome in terms of increased wind energy absorption, while maintaining the economic
feasibility of the investment project.
In classical type of system, low cost electric power (electricity in off-peak time) is used to run
the pumps to raise the water from the lower reservoir to the upper one.
During the periods of high power demand, the stored water is released through hydro turbines
to produce power. Reversible turbine-generator groups act as pump or turbine modes, when
necessary
During peak
times, water is
released from
upper
reservoirs,
generating
energy as it runs
through turbines
to the lower
reservoir
PUMPED HYDRO STORAGE TECHNOLOGIES
Case Study: Multiple Purpose Socorridos System
The Multiple Purpose Socorridos System started operating in
1995 under its initial configuration:
β’ 16 km long string of hydro tunnels and canals, allowing the transfer of water
collected on the higher altitude and more raining northern side of the island, to
the southern side of the island
β’ Loading chamber in CovΓ£o with a maximum capacity of just 7 500 m3
β’ Hydroelectric station with three Pelton turbines with 8 MW of capacity and a
flow of 2 m3/s each
β’ Connection to the StΒͺ QuitΓ©ria mini hydropower station, equipped with a single
Pelton turbine with a nominal flow of 1 m3/s
Case Study: Multiple Purpose Socorridos System
Initial Configuration: only Hydropower Station
Case Study: Multiple Purpose Socorridos System
Current Configuration: plus with Pumping Station
Operation in turbine mode
In pump mode
- the load diagram is further smoothed out with increased RES penetration possibility, of up to 30%
of the electricity production share, and reduced need for spinning reserves.
- this results in the avoidance of 100 ktonnes of fuel oil importing, which corresponds to a 4 Mβ¬
savings per year, and to an avoided emission of 300 ktonnes of CO2.
- how the Socorridos System affects the daily load diagram, showing how wind penetration is maximized
due to pumping in low peak demand hours, and thermal generation is replaced by hydro production in
peak hours
Madeira pumped-hydro-storage system operation
1- Transformation in a reversible power station maximizes the hydropower production;
2- Allows overcoming the limitations imposed by the water scarcity;
3- Allows a greater penetration of clean and renewable energies (such as the wind and solar energies).
Movie
Currently are under construction several hydro-schemes in around 130
countries, and many others in design, adaptation and rehabilitation.
International overview
Hydropower Potential
~ Continents
Theoretical
Potential Installed Power
Production in
average year
To be installed (under
construction) Planned Power
(GWh/year) (MW) (GWh/year) (MW) (MW)
Africa > 2 461 967 23 482 97 519 5 222 27 868 - 91 723
Asia + Russia and Turkey > 19 716 941 401 626 1 514 198 125 736 205 156 - 340 453
Australia + Oceania ~ 657 984 13 370 37 138 67 420 - 2 768
Europe > 2 817 477 179 152 541 908 3 028 15 793 - 18 516
North America > 7 600 775 169 105 689 314 7 798 34 784 - 52 001
South America > 6 639 249 139 424 670 780 19 555 78 445 - 96 103
World > 39 894 392 > 926 159 > 3 550 856 > 161 406 362 466 - 601 565Based on: H&D (Hydropower and Dams) World Atlas, 2010; ICOLD β International Commision on Large Dams; ESHA β European Small Hydro Association; IWRA β International Water
Resources Association, IWA β International Water association; IWMI β International Water Management Institute; UNEP β United Nations Environment Programme; UNESCO-IHE β Institute
of Water Education; Water Aid.
World hydropower technical potential
The highest percentage of undeveloped potential is located in Africa (92%), followed by Asia (80%), and
Latin America (74%), even though this region is also characterized by two of the top ten hydropower
producers (in 2018)
Energy security (classic approach)
Base load β minimum level of consumption throughout the day
β’ Power plants that operate at low cost during the 24 hours
of the day throughout the year (coal or nuclear)
Intermediate load β predictable variation of consumption
throughout the day
β’ Power plants that are capable of working within minutes
with moderate costs (renewables and natural gas )
Peak load β sudden increase in consumption
β’ Highly flexible power plants that are capable to go to full
capacity within seconds (hydro)
Spinning reserves β power plants that are active and ready to be connected to the grid.
Pumped Hydro Storage
In PHS systems, energy is transformed into
potential energy that is stored in the form of
water level, by pumping water from a lower
reservoir to a higher level reservoir
In a traditional configuration PHS systems take
advantage of the difference between low and
high demand period of electricity prices to
generate its revenues
Hydropower systems
With the highest flexible technology for power generation. Hydro reservoirs provide built-in energy
storage, and the fast response time of hydropower enables to optimise electricity production across
grids and meeting sudden fluctuations in demands
Pumped Hydro Storage
System ImprovementsDouble Penstock
The use of a separate penstock for the pump and turbine increases the systemβs flexibility and
reduces the time lag between storing and generating operation switch.
In isolated grids it allows for the storage of a highly variable energy source while at the same time
providing a stabilized energy for consumption.
Advantages:
- to store energy
- to firm variability of energy generated by
intermittent renewable sources
- to compensate the fluctuations of the loads
Construction of new
hydropower plants
+
Upgrade projects of
existing hydropower
plants
Portugal doubled the
installed capacity in few
years
Relevant Remarks
The high complementarity between renewable sources is the utmost advantage;
Pumping storage is an effective solution to address intermittent renewable energy
failures;
Hydraulic machines of Francis or PAT best suited for reversible hydroelectric systems
as they can also perform the power production and the pumping with good
efficiencies;
The use of the ocean as a lower reservoir saves the construction costs for the lower
reservoir.
New projects of pumped-storage systems in Portugal:
Baixo Sabor Power Plant:
- 4 reversible groups
- P = 171 MWCarvΓ£o-Ribeira:
-2 reversible groups
- P = 256 MWExamples of upgrade
Projects:
- Alqueva II
- Bemposta II
- Venda Nova III
In Portugal was increased in
pumped-storage hydropower
systems from 5 GW to 7 GW by
2020
Portugal currently leads in Europe, the countries
that will invest more in hydropower and solutions
with pumped storage (World Atlas, 2010)
Alto RabagΓ£oThe opportunity lies in using the dam reservoir of hydroelectric facilities
Floating Solar Pannels
Converting solar energy into electricity through photovoltaic technology is an increasingly
cheap and efficient process. Portugal has one of the highest solar resource levels of
European countries, but using it means occupying very significant geographical areas.
The opportunity lies in using the dam reservoir of hydroelectric facilities. Thanks to this the
occupation of other areas of recognized utility (for agriculture, for example) can be avoided
and it's possible to make use of the connection to the already installed electrical network
that hydroelectric stations do not use constantly. Because there is more sunlight when there
is less rain and vice versa.
Recognizing this context and this opportunity, EDP opened, a floating solar photovoltaic
power plant at the dam reservoir of RabagΓ£o river in Montalegre and the Alqueva Floating
Photovoltaic project.
β Alto RabagΓ£o
β A pioneering project at the European level, the floating photovoltaic solar power plant at the
RabagΓ£o river basin, in Montalegre, tests the cooperation between solar energy and hydro,
as well as the environmental and economic advantages of this new technology.
β With 840 solar panels occupying an area of 2500 square meters, the platform, which
results from a partnership between EDP Produção, EDP Renewables and EDP Comercial,
has an installed capacity of approximately 220 kWp and an estimated annual production of
around 300 MWh.
β EDP has invested 450.000 euros to move forward with the installation of this pilot unit,
which will help in assessing the implications, advantages and disadvantages of the
installation on floating platforms of the photovoltaic conversion panels and their exploitation
together with the hydroelectric production. It is also intended to prove that this solution has
clear environmental benefits in the water body, and because it reuses existing installations,
avoiding the construction of new transport lines.
https://youtu.be/bFevGbcHq8M
Alqueva Dam:
- Guadiana river
- started operating in 2004
Objectives:
- electricity supply;
- public water supply;
- irrigation of 115 000 ha of agricultural land;
- implementation of leisure and tourism
infrastructures.
2 reversible groups with Francis turbines
P= 256 MW
Improvements in the
wind and solar
energy sectors
Upgrade Project+ 2 reversible groups
+ 256 MW
Alqueva II
https://youtu.be/_EEtXr73N5U
Upgrade Project Alqueva II
Regulation of the
grid:
- Hours of low
demand and low
electricity price
- Hours of high
demand and high
electricity price
PUMP
TURBINE
Upgrade Project Alqueva II
Simulating the operation PedrΓ³gΓ£o-Alqueva:
-Average level in Alqueva ~ 147m
-Level in PedrΓ³gΓ£o ~ 82,5 m
(half of the capacity)
- H = 64,5 m
- Qt = 192 m3/s
- Qp = 162 m3/s
Daily cycle: 5 hours β turbine
6 hours β pump
Qt/Qp= 1,19
Optimization: opportunity in energy tariff
= maximum profitability
= minimum level of energy price
Pure reversibility cycle:
Qt x Tt = Qp x Tp
Qt: turbine discharge
Qp: pump discharge
Tt: Time of operation of turbine
Tp: Time of operation of pump
Pumped-Storage using Seawater Pumped-Storage Power Stations
Seawater Pumped-Storage:
- 1st Seawater Pumped-Storage Power Station: Okinawa, JapΓ£o (1999)
- Lower reservoir = SEA
- Volume of the reservoir and volume of water unlimited
Some cares:
- Corrosion
- Adhesion of marine organisms
Remarks about Pumped-storage and hydro solutions
53
- improves energy efficiency
- generates clean energy:
-withou CO2 emissions
-without harming the environment
-allowing to overcome the scarcity of resources
(reutilization of the same hydrological source)
-without contributing to global warming
Renewable energies (subject of particular relevance in developed and developing countries)
Need of a good and competitive option to store energy generated by intermittent sources:
Pumped-Storage:Without storage, the energy
produced, may be wasted,
if not needed.
SMART PUMPED HYDRO SYSTEMS (PHS) β integrated solution
It also contributes to fossil fuel
savings, without jeopardizing the
reliability of the electrical system
and maintaining end-user
satisfaction indexes for electricity
The challenge of using renewable sources such as hydro, wind and solar power is their variability,
intermittency, unpredictability, and dependence on the weather
Combining renewable energy resources is the best way to overcome energy shortcoming, which not
only provides more reliable power systems increasing the storage capacity but also leads to the
reduction in climate change effects
Through proper
management of both
resources, it is possible
to guarantee a uniform
power supply to the grid
PUMPED HYDRO SYSTEMS (PHS)
Renewable-based technologies can make water-energy accessible for domestic, industry and
agricultural purposes, improving supply security while decoupling growth in energy from fossil fuels
RENEWABLE ENERGY TECHNOLOGIES
Renewable energy technologies offer opportunities to address trade-offs and to leverage on
synergies between sectors enhancing the water and energy nexus
However, connecting renewable power plants to the grid can cause dynamic controlling problems if
the electricity network is not prepared for handling such variations due to the intermittency of
renewable sources availability
Problem
Therefore, a continuous and reliable power supply is hardly possible without energy storage. Using
an energy storage system, the surplus energy can be stored when the power generation exceeds
the demand and then be released to cover the rest hour periods when the net load exists, providing
a robust flexible back-up for intermittent renewable sources
Solution
This has the advantage in
increasing the system flexibility
and reliability, decreasing the
variability of renewable sources
availability, since the variable
power output can be levelled
out due to a complementary
nature between renewable
resources through their
integration in the hydropower by
a pumped storage solution
RENEWABLE ENERGY TECHNOLOGIES
The problem of designing a PHS system is complex and, although it could be done on an iterative
procedure, by defining several possible scenarios and comparing the technical and economical
results, this would be a time-consuming approach, possibly not leading to the optimal results.
Therefore, it is important to have a more systematic approach
RENEWABLE ENERGY TECHNOLOGIES
DESIGN OF A HYBRID SYSTEM
Undersized hybrid
system is more cost-
effective, but may
not be able to meet
the load demand and
viability studies
HYBRID SYSTEM
SIZED
Oversized hybrid
system satisfies the
load demand, it can be
an unnecessarily
expensive solution
Optimum size of the hybrid renewable
energy power system depends on several
simulations based on specific mathematical
models and system components management
towards the best solution
HYBRID AND PUMPED HYDRO STORAGE TECHNOLOGIES
Different energy resources can be combined building an integrated hybrid energy system that
complements the drawbacks existing in each individual energy solution
Therefore, the design goals for hybrid power systems are the minimization of power production
cost, purchasing energy from the grid (if it is connected), the reduction of emissions, the total life
cycle cost and increasing the reliability and flexibility of the power generation system
The pumped hydro storage can be seen
as the most promising technology to
increase renewable energy levels in
power systems
In some locations, the
solar and wind resources
have an anti-correlation,
complementing each
other and giving a
combined less variable
output than
independently
Hydro, wind, solar and pumped hydro storage (PHS), as hybrid power solutions, constitute a
realistic and feasible option to achieve high renewable levels, considering that their
components are properly sized
HYBRID AND PUMPED HYDRO STORAGE TECHNOLOGIES
The distribution of daily-mean wind
(green) and solar PV (red) power output
each month, both scaled by their long-
term all-year average
PHS schemes currently provide the most commercially important means of large-scale grid
energy storage and improve the daily capacity factor of the generation system
Pumped hydropower energy
storage stores energy in the
form of potential energy
that is pumped from a
lower reservoir to a higher
one putting the water
source available to turbine
to fit the energy demand
HYBRID AND PUMPED HYDRO STORAGE TECHNOLOGIES
The principle of PHS is to store electrical
energy by utilizing the potential energy of
water.
β’ In periods of low demand and high
availability of electrical energy the water
will be pumped and stored in an upper
reservoir/pond.
β’ On demand the energy can be released
respectively transformed into electrical
power within a short reaction time.
Therefore PHS can adjust the demand supply
to balance respectively, reducing the gap
between peak and off-peak hours, and playing
an important role of levelling other power
generation plants and stabilizing the power
grid.
HYBRID AND PUMPED HYDRO STORAGE TECHNOLOGIES
Basically there are four types of PHS concepts which are distinguished by the water regime
Off-stream, this type consist of an upper and lower reservoirs
connected by a power waterway. Off-stream are PHS mainly
divided in single purpose (pure pumped storage) or multiple
purpose usage
Pump-back, reversible units installed at an on-
stream hydropower plant to firm up peaking capacity
during occasional periods of low flow
HYBRID AND PUMPED HYDRO STORAGE TECHNOLOGIES
Diversion type or so called water transfer PHS divert water
from one river basin to another
Seawater, (the Okinawa Seawater demonstration
plant) by utilization of seawater for the lower
reservoir has been built in Japan
HYBRID AND PUMPED HYDRO STORAGE TECHNOLOGIES
This system is equipped with a
photovoltaic (PV) system array, a wind
turbine, an energy storage system
(pumped-hydro storage), a control
station and an end-user (load)
A typical conceptual pumped hydro storage system with wind and solar
power options for transferring water from lower to upper reservoir:
This whole system can be isolated from
the grid, i.e., as a standalone system or
in a grid connection where the control
station can be the grid inertia capacity.
This is currently the most cost-effective
means of storing large amounts of
renewable energy, based on decisive
factors, such as, capital costs, suitable
topography and climate changes
challenges
HYBRID AND PUMPED HYDRO STORAGE TECHNOLOGIES
The design criteria are mainly derived by the power market demands and actual site characteristics
HYBRID AND PUMPED HYDRO STORAGE TECHNOLOGIES
To develop a PHS project the design criteria have to be transferred into a technical concept
There is no common approach to transfer
design criteria to develop a PHS project
It is a βpuzzleβ of engineering judgment
and knowledge transfer as well as
experience
HYBRID AND PUMPED HYDRO STORAGE TECHNOLOGIES
The layout of the HPHS project will be developed based on the site existing
characteristics
Desirable site characteristics:
β’ Geological conditions should be suitable;
β’ Head is proposed to be as high as suitable;
β’ Length of the penstock should be not too
much long;
β’ Suitable size for sufficient power installation;
β’ Site should be located reasonable closely to
load centers or transmission corridors
HYBRID PUMPED HYDRO STORAGE
Machine types differ in their flexibility to participate in the reserve markets
and in their investment cost
HYBRID PUMPED HYDRO STORAGE
Ternary set systems allow to significantly reduce transition time
compared to conventional reversible turbines. A ternary set consists
of a separate turbine and pump on a single shaft with an electric
machine that can operate as either a generator or a motor
The main available solution to realize variable speed operations are
doubly fed induction machines (DFIMs) and converter fed
synchronous machine (CFSM)
In the DFIM the stator is directly connected to the grid, while the
rotor windings are connected via a power electronic converter using
slip rings. Through frequency control of the rotor current, it is
possible to have variable-speed operation while the stator frequency
and voltage remain constant. In CFSM a synchronous machine is
connected to the grid via a full-rated converter. Therefore, the
frequency of the motorβgenerator can vary from the grid
Machine types differ in their flexibility to participate in the reserve markets
and in their investment cost
HYBRID PUMPED HYDRO STORAGE
The power market demands determine the machine configuration and the
storage volume
β’ How much additional
pumped storage fits to
the energy market?
β’ How much flexibility is
required in todayβs
market?
β’ Which machine type
should be applied?
β’ What is the market
optimal capacity and
storage reservoir size?
HYBRID PUMPED HYDRO STORAGE
The power market demands determine the machine configuration and the
storage volume
HYBRID PUMPED HYDRO STORAGE
Transient analysis during pumping must be evaluated as characteristics differ
significantly from turbine mode
Hydraulic transient events are disturbances in the
water conduit cased during changes in the state
from flowing to non flow conditions and vice versa
Typical cases are:
β’ Turbine/Pump start up or shut down,
β’ Valve opening and closing (variation in cross-
sectional flow area),
β’ Changes in boundary conditions (e.g. adjustments
in the water level at reservoirs)
β’ Rapid changes in demand conditions,
β’ Changes in transmission conditions, and
β’ Pipe / tunnel filling or draining
The main design techniques are used to
mitigate transient conditions such as:
β’ Alteration of pipeline characteristics
β’ Improvement in valve, turbine and
pump control procedures, and
β’ Design and installation of surge
protection devices
HYBRID PUMPED HYDRO STORAGE
Transient analysis
Special attention must be given to
the extremes: the maximum and
minimum energy heads, discharges,
power, maximum changes of load
from speed (full load rejection, to
partial or full load)
Pump / Turbines normal operating
conditions represent all 15 lines.
Normal modes of operation for hydro power plants
HYBRID PUMPED HYDRO STORAGE
Transient analysis Normal modes of operation for hydro power plants
Colored lines 14 and 15 are cases
when control and protection system
trigger emergency shut-down at
overspeed and overflow
If not properly designed these 14 and
15 cases are sources of troubles and
accidents
The turbine over speed signal was
reached and emergency stop level
close the guide vanes which has been
enough to result in an accident
HYBRID PUMPED HYDRO STORAGE
Transient analysis
An installation having unstable
characteristics, in a trial/error
corrector mode (PID) operation,
pump turbine excited penstock
resonance and resulted in
penstock rupture and casualties.
We can see the measured
pressure resonance in this
operation prior to penstock rupture
HYBRID PUMPED HYDRO STORAGE
Transient analysis
Preliminary analyses and the engineerβs experience are useful for deciding whether additional
devices will be needed for diminishing the amplitudes of the pressure surges or preventing
pressure surges
Those devices might be surge tank(s), pressure regulator valves, air injection, governor controls,
or air chambers. If the system includes any of those devices, assume that the devices will
function correctly when making the analyses for the normal cases
Reducing the rate at which valves or wicket gates close also can diminish or prevent pressure
surges. Analyze the various cases to find which initial conditions, together with the various
transient conditions, result in the most extreme high or low pressures or the most extreme high or
low rotating speeds
HYBRID PUMPED HYDRO STORAGE
https://youtu.be/yfZoq68x7lY
Multi-criteria tool
An electrical generating system composed primarily
by wind and solar technologies, with pumped-storage
hydropower schemes, is defined, predicting how
much renewable power and storage capacity should
be installed to satisfy renewables-only generation
solutions
It explores the combined
production of hydro, solar and
wind, for the best challenge of
energy storage flexibility,
reliability and sustainability
Technique based on a multi-
criteria evaluation, for a
sustainable technical solution
based on renewable sources
integration
MULTI-CRITERIA TOOL
OPTIMAL DESIGN OF A HYBRID SYSTEM
The purposed mathematical model can predict how much wind, solar power and pumped hydro-
storage energy capacity should be installed to satisfy a hybrid renewable solution
As for solar energy although less
fluctuating, it only works during day light
hours. It offers more reliable power and
can be committed and managed, using
relatively smaller energy storage systems
to provide continuous and quality power
Wind is highly fluctuating meteorological
parameter changing every hour and
annually. Therefore, to connect wind power
with the grid and assure quality power
supply, large energy storage systems are
required
Pumped hydropower storage plants have several advantages:
(1) flexible start/stop and fast response speed,
(2) ability to track load variations and adapt to severe load changes,
(3) capacity to modulate the frequency and maintain voltage stability and
face climate change and reduce footprint effects on an integrated solution.
The optimal design of a hybrid solarβwind-
system supported by a pumped-based hydro
scheme can significantly enhance the technical
and economic performance for efficient energy
harnessing
The multi-variable techniques are also known
for their accuracy and simplicity when
encountering complicated optimization
problems
The main objective is to analyze the
capacity of such a system to be able to
store the excess of wind/solar energy, at
times when energy demand is lower, and
provide reserves in the form of hydropower
at times when consumption exceeds the
wind/solar production or, alternatively,
making the system self-sufficient
Multi-criteria tool
OPTIMAL DESIGN OF A HYBRID SYSTEM
πΈππ‘, πΈπ
πdepend on the tri-time tariff
Multi-criteria tool
Vi is for water volume at time (i)
Ei is for energy at time (i)
Di is the demand at time (i)
Hi is for hybrid power/energy available
at time (i)
Si is the solar energy at time (i)
Wi is for wind energy at time (i)
The superscripts (p, t, res) are assigned
for pump, turbine and reservoir
If π π
Yes
Start
Input demand data of energy demand (D), wind (W) and solar (S) along the time
Use dimensionless values, depending on the arbitrated peak consumption and the installed wind and solar power (using peak factors ( ))
e.g.,Wind , Solar , , Storage ,
No
Calculate the wind/solar hybrid power/energy
available: π π π
No
πΈππ
ππ
πΈππ‘
ππ‘
No
No No
π π= πΈππ
ππ πΈπ
π π
πΈππ‘ π π
ππ‘ πΈπ
π‘ π‘
YesYes
π π
ππ‘ π
π
π π
ππ‘ π
π π
ππ
YesYes
ππ π
π π
ππ‘ π‘
π‘ π‘
πΈππ‘, πΈπ
π π
π‘ π π π
Qtmax is the maximum turbine flow
is the maximum pumped flow Qpmax
is the maximum pumped volumeVpmax
Vtmax is the maximum turbine volume
Vpi is the pumped volume at time (i)
Vti is the turbine volume at time (i)
is the maximum pumped energyEpmax
Etmax is the maximum turbine energy
Epi is the pumped energy at time (i)
Eti is the turbine energy at time (i)
OPTIMAL DESIGN OF A HYBRID SYSTEM
If π π
Yes
Start
Input demand data of energy demand (D), wind (W) and solar (S) along the time
Use dimensionless values, depending on the arbitrated peak consumption and the installed wind and solar power (using peak factors ( ))
e.g.,Wind , Solar , , Storage ,
No
Calculate the wind/solar hybrid power/energy
available: π π π
No
πΈππ
ππ
πΈππ‘
ππ‘
No
No No
π π= πΈππ
ππ πΈπ
π π
πΈππ‘ π π
ππ‘ πΈπ
π‘ π‘
YesYes
π π
ππ‘ π
π
π π
ππ‘ π
π π
ππ
YesYes
ππ π
π π
ππ‘ π‘
π‘ π‘
πΈππ‘, πΈπ
π π
π‘ π π π
Multi-criteria tool
This model was
developed for a time
scale of one average
year, assuming hourly
variations, where
dimensional data
regarding variations in
electricity demand and
wind/solar energy
production
OPTIMAL DESIGN OF A HYBRID SYSTEM
The proposed dispatch model selects the best combination of peak factors to reach the optimal
solution in terms of efficiency, energy exploitation, cost, and footprint
The peak factor is the ratio of the total flow to the average daily flow in a water system and is
important in the study of a water system to determine potential water consumption values
The pumping process is done during the empty hours (i.e., of lower demand) and the hydroelectric
generation through peak hours (i.e., for highest demand)
The consumption during the off-peak hours is satisfied exclusively by wind/solar, while in the
remaining period, the power generation is complemented by hydro, if insufficient wind/solar
production is verified
Excess wind/solar energy that is not used for consumption in the system is used for pumping. In this
way, it is possible to reduce the purchase costs of electricity from the grid
OPTIMAL DESIGN OF A HYBRID SYSTEM
Operating Principles and Important Restrictions
π½ππππππ > π.πππ½πππ
πππ
π½ππππ = π½π π
πππ + π½ππ π½π
π
π½ππβ₯
πΈππππ
πΈππππ π½πππ
π, π½π
π β₯πΈπππ
π
πΈππππ
π½ππππ
βπ¬π = π―π π«π
π°π π½ππππ β₯ π½πππ
πππ β π½ππ
= π
π¬πππ π½ππ
= π¬πππΌπ πππ― Γ ππππ
π°π π½ππππ β€ π½πππ
πππ β π½ππ = π
π¬πππ π½ππ = π¬π
π πππ―πΌπ Γ ππππ
π°π ππππ = πππππππ ππππππ β π¬ππ
= π·πππ πππππ πππππππππ , π¬ππ = π
π¬πππ π¬ππ
= π , π¬ππ = βπ¬π
OPERATING CONDITIONS RESTRICTIONS CONSIDERED
π¬ππ π·πππ πππππ π ππππππ
OPTIMAL DESIGN OF A HYBRID SYSTEM
As the pumping system works in the early hours of the day (0-7h) the system presents sufficient
reserves to be able to assist intermittent renewable energy production failures during the remaining
period
πΈππ‘, πΈπ
πdepend on the tri-time tariff
The daily cycle for electricity supply, dictated by
the tri-time tariff applied in mainland Portugal
TARIF PERIOD WINTER SUMMER
WORKDAYS
Peak 5h/day 3h/day
Half-peak 12h/day 14h/day
Normal off-peak 3h/day 3h/day
Super off-peak 4h/day 4h/day
SATURDAYS
Half-peak 7h/day
Normal off-peak 13h/day
Super off-peak 4h/day
SUNDAYS Normal off-peak 20h/day
Super off-peak 4h/day
1
The pumped hydro storage (PHS) is the energy
storage solutions, consisting on a separated
pump/motor unit and a turbine/generator unit
to manage the other renewable sources inputs
to face the energy demand
OPTIMAL DESIGN OF A HYBRID SYSTEM
The benefit in using medium-head pumped-storage plants is to shorten transmission lines from the
alternative energy sources to the hydro storage facility, thus minimizing grid overloading due to
energy transfer across a country
Moreover, it has the advantage of locating wind or solar farms in higher topographic zones
The proposed solution focuses on a
converter connected to a
motor/generator. The efficiency
considered can vary between 60%
and 80% for pump/turbine mode,
respectively
OPTIMAL DESIGN OF A HYBRID SYSTEM
Guidelines
GUIDELINES
PHS solutions demonstrate that technically the pumped-storage hydropower system integrating other
renewable sources is an attractive energy solution
The dynamic contribution of individual sources follow different patterns, due to the stability of hydro by
pumping and random variability of other energy sources and the energy demand
Employing the three technologies in a complementary and balanced manner, the hybrid system could
generate and store electricity at low cost, facing climate changes and reducing the footprint of electricity in a
self-sufficient solution
A consistent multi-criteria framework can be developed to optimize the availability and storage of renewable
energy, selecting the best combination of peak factors to achieve the optimum solution in terms of efficiency,
energy use, costs and footprint
Important considerations are highlighted and summarized from this multi-variable process:
The optimization showed that in a hybrid solution, turbines and pumps can be used at the same time
depending on the intermittency, availability and optimized variables, which include different renewable
sources, the storage capacity and the load demand.
The pumping system can be supplied by intermittent renewable sources when available, and at the
same time, can be guaranteed a constant power production by hydraulic turbines.
The only one pipe for the P/T solution requires different hours for each operation or the use of separate
pipes, which can offer more operating flexibility, where one is kept running, the other is stopped or in
operation, depending on the sourcesβ availability, constancy or intermittency, type of storage or type of
grid connection.
Three sources can be combined considering different pump/turbine installations, wind/solar powers
and different water batteries as volume capacities.
GUIDELINES
After selecting the best installation power for P/T, different conditions must be tested, changing the
wind/solar powers and the water storage capacity.
The results obtained show the process of selecting the best scenario is not straightforward, depending
on the final goal. Therefore, this type of analysis unfolds in important points:
For a specific condition, from the point of view of reliability and flexibility, there is a better use of
hydropower, specifically to accommodate the largest shares of other intermittent renewable (solar and
wind) energies with a better bridge and compensation between these energy sources
In addition, other hypothesis may involve an increase in the installed wind power from an operational
point of view, but there is an increase in satisfactory consumption
For the conditions where storage capacity increases, this does not make a significant contribution to
the best operation of the system. As a result, the reservoir is oversized to meet the satisfied
consumption, i.e., there is a dependency not only on the maximum daily energy use of the system but
also on the hydropower system
GUIDELINES
Thus, surplus energy from renewables produced at times of low demand (e.g., solar power in summer) can
be stored and ready for release when demand rises;
With more advantages and greater economic viability also in terms of CO2 emissions. The selected hybrid
solution is less expensive, considering the powers installed, with a lower initial capital cost
Additionally, it can be concluded that replacing fossil fuels by renewable energies requires:
(i) RES installations (e.g., wind turbines) widely;
(ii) using a range of different intermittent energy sources, especially those that are partially
complementary (e.g., sunny weather often means light winds and vice versa);
(iii) matching with suitable management of energy sources in periods of high demand. Still, there is
clear evidence of how all these modern integrated techniques for complementarity between
renewable sources can significantly reduce electricity tariffs and increase the reliability of the
energy supply as main targets of hybrid-energy solutions.
GUIDELINES