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Microhydro training – Day 2
Mechanical, Electrical, Project
proposal
Myanmar Off-Grid
Renewable Energy
Demonstration Project
(ADB TA 8657 MYA)
1 – 4 Nov, 2016
Taunggyi, Shan State,
Myanmar
Day 2: system design, metering, tariffs, monitoring and
evaluation, and business models, grid interconnection
• Turbine options
• Reaction (Francis, propeller, etc) and impulse turbines (Pelton, Turgo, etc.)
• Head and flow curves
• Generator types
• Synchronous
• Induction
• Permanent magnet
• Load calculations (use spreadsheet to aggregate individual load data and create load
curve).
• Load controllers
• GridShare
• Metering and tariffs
• Interconnecting with the main grid
• Attributes of attractive projects
• Q&A
Confidential
Any questions from yesterday?
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0 30 60 90 120 150 180 210 240 270 300 330 360
Day
Flow [m3/s] 1986 1987
1988 1989
1990 1991
1992 1993
1994 1995
1996 1997
1998 1999
2000 2001
Watersheds
Micro-hydro turbine types
Pelton Turgo CrossflowPropeller/ Kaplan
Centrifugal pump
Francis
Turbine application
http://www.tycoflowcontrol.com.au/pumping/welcome_to_pumping_and_irrigation/home4/hydro_turbines/turbine_selection (April 18, 2003)
Efficiency and Flow
0.2 0.80.60.4 1.0Fraction of Maximum Flow
Effic
iency
50
%
00%
100
%Pelton and
Turgo
Crossflow
Francis
Propell
er
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
• Preferred turbine for hydro-power,
when the available water source
has relatively high hydraulic head at
low flow rates.
• Vary from 40 watts to 400 MW
Pelton turbines
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Pelton
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Turgo
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Turgo
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Turgo
Cross-flow turbines
Cross-flow turbines: Simple, affordable
The runner can easily be adapted to the flow, by changing its width.
Thus it is easily possible to build the turbine to fit precisely the site
conditions.
The simple design allows good
standardisation and manufacturing
without sophisticated manufacturing
facilities.
The costs are low compared
with other turbine designs.
Cross-flow turbine Entec T-15
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Crossflow
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Confidential
Confidential
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Propeller (Kaplan)
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Propeller
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Propeller
Francis turbine
Francis turbine
Francis
Pump as turbine – Mae Wei village, Tak Province
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Quality Measured in Water analogy
Power Watts (W)
Kilowatts (kW = 1000W)
Megawatts (MW = 1000 kW)
(power)
Voltage Volts (V)
Kilovolts (kV = 1000 V)
Pressure
Current Amps (A) Flow
Resistance Ohms (Ω) Resistance to flow
Electricity
Power = Voltage x current (Watts = volts x amps)
Generators
• Permanent magnet
• Wound rotor synchronous
• Induction (Asynchronous)
Permanent magnet
rotor
stator
Permanent Magnet Generator
Rotor has permanent magnetsAdvantagesNo brushes
Efficient
DisadvantagesGenerally limited in size to several kW
field not adjustable
Used in many all stand-alone applications.
Single phase up to 10 kW.
Three-phase up to 70,000 kW
Advantage:
Industrial standard
Frequency and voltage regulation
Disadvantage
Wound rotor – not tolerant to overspeed
Harder to connect to grid
(wound rotor) Synchronous Generator
(Wound rotor) Synchronous Generator
Most large machines use field coils to generate the magnetic field.
Rotating magnetic field induces alternating current in stator windings.
AVR
Rotor Field WindingExciter Winding
Exciter Field WindingStator Output WindingRectifier
(wound rotor) synchronous generator
Big50,000,000 watts
small2,000 watts
Asynchronous (Induction) Generator
Just an induction motor with negative slip.
Used with:
grid-tie system (up to 1 MW)
Off-grid stand-alone (often in ‘C-2C’ configuration)
Can be used with battery based systems
Induction motor/generator
Induction Generator
AdvantagesSimple and robust.
Tolerant to overspeed
Readily available
inexpensive
DisadvantagesFrequency regulation ‘loose’ in stand-alone applications
Requires external excitation
When used in off-grid,
an Induction Generator Controller
(IGC) ‘IGC’ controls voltage
Induction grid-tie example
1 MW Mae Ya
Selecting a Generator
Type (synchronous, induction, permanent magnet)• Stand-alone or grid-tie
Single or Three phase
Voltage• Loads• Transmission
RPM• 3000 rpm (single pole), 1500 rpm (double-pole), or 750 rpm (four-pole)
• Where possible, pick generator speed and turbine combination that avoids gears or belt drive to minimize friction losses and additional moving parts
Size
Selecting a generator: IP rating IP = Ingress Protection.
IP rating is used to specify the strength
of the enclosure that surrounds
electronic equipment
Micro-hydro: IP44
Voltage and Frequency Regulation
Confidential
Voltage Regulation
230 volts
Voltage and frequency control
• Controlled by generator’s Automatic
Voltage Regulator (AVR)
• Controlled by Electronic Load
Controller (ELC)
Confidential
Confidential
Electronic load controller (ELC)
Turbine &
generator
Electronic Load
Controller (ELC)
Load
Ballast
Electronic Load Controller
Mechanical Governing
As load varies, mechanical control keeps frequency constant by
varying water flow
Advantage:
Saves water
Disadvantage:
Electro-mechanical moving parts
Slower reacting
More expensive
Confidential
Determining load
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Load aggregation – household example & Excel lesson!
Detailed analysis for MHP systems >30 kW
demand estimate for a typical representative household (domestic use)
to be filled in
to be calculated
5:0
0
6:0
0
7:0
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1985
1988
1991
1994
1997
2000
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1000
2000
3000
4000
5000
6000
7000
Watts
Time of day
Year
Hourly load curve, by year from 1985 to 2000. Graph based on an appliance usage survey of 35 families in Mae Kam Pong village, April and June 2001.
Demand estimate for social infrastructure
Demand estimate for productive end use
Confidential
total demand
Typical load curve over the day
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5
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30
1 3 5 7 9 11 13 15 17 19 21 23
Time [h]
load
[kW
]
Productive use
Social Infrastructure
Domestic use
Detailed analysis for MHP systems >30 kW
Confidential
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
200,000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Year of MHP Operation
En
erg
y D
em
an
d [
kW
h]
Demand growth
productive use
Demand growth
social infrastructure
Demand growth
domestic use
0
10
20
30
40
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Year of MHP Operation
Peak D
em
an
d [
kW
]
Projection of demand growth
Confidential
Gridshare – a technology to share limited micro-hyropower
ELC keeps electricity stable when there is surplus…
GridShare can help when there isn’t enough
Rukubji Micro-Hydro System
• Installed 1986• Rated at 40 kW
Limitations of Mini-Grids
Rukubji’s isolated micro-hydroelectric
system experienced daily brownouts
during times of peak loading.
Peak loads consisted
of resistance-heating
kitchen appliances
used at meal times.
Power supply transformer Voltage regulator
Relay
Current transformer
Micro-controller
Voltagedivider
Smoothing capacitor
Image credit: Tom Quetchenbach
GridShare Circuit Breaker
Utility Meter
GridShare Final Design
Three-Prong Approach to Shift Demand
FeedbackGreen light: low demandRed light: brownout
EnforcementDuring brownouts, prevents the use of large appliances
EducationHelp residents understand their electrical system and discuss ways to alleviate brownouts
GridShare Installation 2011
GridShare Results
•Electrical data indicated a reduction of over 90% in severe brownouts
•LED lights helpful and appreciated
•Reduced spoiled rice, residents stated the grid was more predictable
•Some expressed frustrations with restrictions of red LED
•Community decided to keep GridShares installed
Confidential
Metering and tariffs
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
• Mechanism for providing revenue to pay for project and keep it operating
• Can encourage energy conservation
• Can encourage use of electricity at times when there are surpluses
Metering: purposes
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1988
1991
1994
1997
2000
0
1000
2000
3000
4000
5000
6000
7000
Watts
Time of day
Year
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Tariff type #1: everyone pays the same
Advantages Disadvantages
Simple No incentive to conserve or
load-shift
Not fair (people who use
more should pay more)
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Tariff type #2: based on appliances & lights
Advantages Disadvantages
Simple No incentive to conserve
Easy to cheat
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Tariff type #3: subscription tariff – load limiter
Advantages Disadvantages
Simple Still have to collect monthly
payments
Fair Inconvenient to consumers
when load shuts off
Some incentive to load-shift
Inexpensive
Subscription tariff example:
0.25 Amp (60 watts) = 3000 kyat/month
0.50 Amp (120 watts) = 7000 kyat/month
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Tariff type #4: conventional kWh meter
Advantages Disadvantages
Simple Requires monthly meter
readings
Fair Does not encourage load
shifting
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Tariff type #4: pre-pay meter
Advantages Disadvantages
Simple Meters are more expensive
Fair
Can be programmed to be
cheaper in off-peak time
(time of use – TOU rate).
Pre-pay means no need for
bill collection
Users buy electricity in advance like pre-pay cell phone minutes
Confidential
Interconnection to the main grid
Mwenga 4 MW hydro800 households in 15 villages (expanding to 4000) & sells
to the grid
Tanzania
76
Large Plants
Customers
Mini-Grid
Customers
NationalGrid
Small Power Producer
M
M
M
Key: = power from utility = power from SPP = meterM
M
M
M
Before the grid arrives
77
Large Plants
NationalGrid
Customers Customers
Mini-Grid
Small Power Producer
M
M
M
MM
M
M
Key: = power from utility = power from SPP = meterM
Small Power Distributor (SPD)
78
Large Plants
NationalGrid
Customers
Small Power Producer
Customers
Mini-Grid
M
M
M
MM
M
M
Key: = power from utility = power from SPP = meterM
Small Power Producer (SPP)
79
Both SPP and SPD
80
Large Plants
NationalGrid
Customers
Small Power Producer(may operate as emergency
backup plant)
Customers
but with backup electricity provided by old generator
Mini-GridM
M
MM
M
M
Key: = power from utility = power from SPP = meterM
Buyout option
81
Co-existence
Large Plants
NationalGrid
Customers Customers
Extension of
NationalGrid
Small Power Producer
Assets abandoned
83
Induction generator connecting at 380/220 volts
Utility distribution system 22 or 33 kV
Utility distribution transformer
Utility distribution system 380/220 volt
Zone of utility responsibility
Zone of VSPP responsibility
Other Customer
load
Circuit breaker at
interconnection
point
Load of
VSPP
Relay function Details Location
27/59 Undervoltage/Overvoltage Trip CB-A
81 Underfrequency/Overfrequency Trip CB-A
Confidential
Initial micro-hydro assessment
Form NEP-9: Components of Mini-Grid Project Proposal
Confidential
ADB Myanmar Off-Grid Renewable Energy Demonstration Project
Myanmar National Electrification Program
Form NEP-9 Components of Mini-Grid Project Proposal
Mini-grid project proposals should be 10 pages or less, and provide succinct summaries of the following:
1. Village location (including state/region, township, village, and GPS coordinates) and distance away from the
nearest existing medium voltage distribution network (a minimum of 10 miles).
2. Number of households to be served (a minimum of 50 households required)
3. Description of village loads including description of any productive use loads (kW and hours of operation)
4. Estimated daily demand in kWh, including residential, business and public facilities (schools, clinics,
religious buildings, etc)
5. Planned mini-grid fuel type (e.g. micro-hydropower, solar/diesel, biomass, wind, etc.)
6. Measurement of planned renewable energy resource (e.g. flow, head for hydropower)
7. Planned mini-grid capacity (kVA)
8. Description of existing mini-grids (diesel, micro-hydro, etc. – if any) and opportunities to make use of these
assets.
9. Village map showing planned powerhouse and mini-grid, if available
10. Evidence of willingness to pay tariffs by users.
11. Prior experience of the developer in minigrid
Page 87
Assessment of Attractiveness of Project
What makes a potential project attractive?
Page 88
Technical Characteristics of Promising Projects
A micro hydro power site is more likely to be technically attractive, if one or several of the
following criteria are fulfilled:
1. Pressure head: Pressure head is more than 40m.
Explanation: low (<20m) and lower medium head schemes (<40m) tend to be
less attractive because all the hydraulic structures need to be designed for large
quantities of water and have thus considerable size.
This is not only a question of costs but also of complexity and engineering risks.
Exceptions are hydropower plants on irrigation channels (drops), which can be
attractive with heads of down to 7m.
Page 89
2. Site layout: slope of water conductor system or ratio of water head to canal
length is 10% or better.
Explanation: the shorter the canal length required to generate a certain water
head, the more attractive the site is as cost and risks involved will be smaller.
3. Flow: firm capacity is more than demand estimate.
Explanation: firm capacity may be defined here as the power output which can
be generated with the dry season flow. Sites where firm capacity cannot meet
the demand are less attractive because an alternative source of energy would
have to be added.
Page 90
4. Technical risks: low degree of difficulty/risks.
Explanation: a scheme in mostly difficult topography (steep river banks and hill
sides with no space for hydropower structures), in a large and/or meandering
river, in difficult geo-technical conditions (unstable slopes), and with no road
access to or near the site is considered to be of high risk and is thus a less
attractive project.
The degree of difficulty is estimated by assigning the terms high/medium/low
degree of difficulty.
Page 91
5. Distance: Distance of powerhouse to load center/grid connection point is
less than 1 km per 100 kW installed capacity.
Explanation: A small hydro power project with a considerable distance to the
load center/grid connection point is less attractive because of the cost of the
required transmission lines.
6. Consumer density in case of isolated systems: Consumer density is
greater than 30 connections per 1km of transmission and distribution lines.
Explanation: a higher consumer density means that the specific cost for
transmission and distribution facilities are lower.
Page 92
General Characteristics of Promising Projects
Note: Technically attractive projects are not necessarily promising projects! Economic,
financial, social, political and institutional aspects are equally important as purely technical
aspects of Small Hydropower projects.
Broad perspective required to identify promising projects
Promising projects usually have at least 2 of the following characteristics:
• Limited number of technically critical parts
• Synergies with other projects or installations, e.g. irrigation
• Equipment requirement can be manufactured locally
• Substantial equity contribution to project cost is available
Page 93
Promising projects fulfill all of the following criteria:
• Broad political support at all relevant levels can be secured
• No social conflicts due to project implementation to be expected
• No major adverse environmental impacts to be expected
Criteria that further increase the attractiveness of a project:
• Part of the project cost can be covered by a grant or a soft loan
• The project can be linked to other projects to generate synergies
Page 94
Considerations when introducing end uses:
• What is the peak load?
• Can you control peak load? If it is spread amongst many consumers most
likely not
• Is there the possibility to centralize end uses and supply via an independent
transmission? This is preferable?
• Do you have a reliable control system which can handle varying electrical
loads?
Confidential
Thank you!
Contact information
Chris Greacen, Micro-hydro consultant, ([email protected])
Tin Myint Deputy Team Leader (Yangon) ([email protected])