Technologies that Empower Distributed Generation for Rural

Electrification:

Options for Myanmar

Yangon, Myanmar

Dr. Chris GreacenSeptember 5, 2013

Outline

• Mini-grids and conventional grid extension– What happens when the grid arrives?

• Low cost pre-electrification (solar micro-grid)

• Lowering distribution cost for low-density rural electrification (SWER)

• Technologies to help spread out peak loads on mini-grids (MCBs, Gridshare)

2

Electricity for whom?

3

Large Plants

Customers

Small Power Producer

Mini-Grid

Customers

Extending the grid and rural mini-grids

NationalGrid

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Electrification: 26%

5

Electrification: 50%

6

Electrification: 75%

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Rice husk gasifierMyanmar – Kayuklot Township

electricity to 500 households

What to do when the “big grid” expands to reach the “little grid”?

• Option 1: formerly off-grid generators connect to the grid to sell electricity– DC sources (e.g. solar)

• Grid-connect inverter required

– AC generators (e.g. hydro)• Digital relay required

Chris Greacen, Richard Engel, and Thomas Quetchenbach, A Guidebook on Grid Interconnection and Island Operation of Mini-Grid Power Systems Up to 200 kW (Schatz Energy Research Center and Palang Thai, LBNL--‐6224E).

What to do when the “big grid” expands to reach the “little grid”?

• Option 2: purchase electricity from national grid for distribution on mini-grid. – Mini-grid must be built to

acceptable standards

What to do when the “big grid” expands to reach the “little grid”?

• Option 1 + 2: both!

• Mae Kam Pong, Chiang Mai, Thailand• Built by government & community• 40 kW• Used to be off-grid;• Making arrangements to sell electricity to

grid

4 MW hydro - Tanzaniaelectricity to 4000 households in >15 villages & sells to the grid

Affordable pre-electrification

• Pre-electrification is:– safe lighting– cell phone charging– small appliances

• Pre-electrification is generally not:– Agricultural milling– Power tools (electric saws, etc.)– Water pumping

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Pre-electrification solar micro-grid Devergy in Tanzania

www.devergy.com

Devergy

• Every household that wants electricity gets an electronic pre-paid meter

• Electricity paid with cell phone• About $7 per month

Devergy pre-electrification technology

•Every 5-6 households served by an “Enbox”

•60 watts of PV•24 volt, 20 Amp-hr battery•ZigBee wireless electronics, networked to metered households and other Enboxes

•The micro-grid sends update on status of all meters, voltage & current of all Enboxes via cell-phone (GPRS) carrier to internet every 5 minutes.

Single Wire Earth Return (SWER)

• Single wire system using ground as return conductor

• It is used for low cost rural electrification

18Source: Tulloch & Davies, 2006. SWER: New Zealand & Australian Experience. http://siteresources.worldbank.org/EXTENERGY/Resources/336805-1137702984816/2135734-1142446048455/SWERIan.ppt

How it all started• Lloyd Mandeno invented SWER in

New Zealand in 1925.• Seen in 1940’s as preferred

solution for remote, sparsely populated areas.

• 200,000 km of SWER now in NZ and Australia.

• Successfully used in NZ, Australia, Canada, India, Brazil, Africa and Asia for sparsely populated areas

Source: Tulloch & Davies, 2006. SWER: New Zealand & Australian Experience. http://siteresources.worldbank.org/EXTENERGY/Resources/336805-1137702984816/2135734-1142446048455/SWERIan.ppt

How does it work?

Resistance R1 = R (conductor) + R (earth return path)Allow 0.05 ohms/km at 50 Hz for earth return path.

Source: Armstrong. Single Wire Earth Return www.ruralpower.org/oldsite/images/rubberdocs/019_SWER.ppt

Advantages of SWER• Cost Reduction

– One conductor, less pole top equipment– Long, hilltop to hilltop spans– Fewer switching and protection devices– In Australia & NZ:

• Capital cost 50% less than 2-wire, single-phase• 70% less than 3-wire, 3 phase

• Design Simplicity• Reduced maintenance costs

• Estimated 50% maintenance cost saving

• Reduced bushfire hazard – avoid conductor clashing

Source: Armstrong 2002. Single Wire Earth Return

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Limitations of SWER• Restricted load capacity• Requirement for reliable low resistance

earthing at isolating and distribution transformers

• Possible interference with metallic communications systems

• Higher losses due to charging currents

Source: Tulloch & Davies, 2006. SWER: New Zealand & Australian Experience. http://siteresources.worldbank.org/EXTENERGY/Resources/336805-1137702984816/2135734-1142446048455/SWERIan.ppt

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Technologies to help reduce peak loads on micro-hydro

mini-grids

Voltage drops

5am

7am

9am

11am

1pm

3pm

5pm

7pm

9pm

11pm

S1

0

100

200

300

400

500

600

wat

ts

Miniature Circuit Breakers (MCBs) or PTCs to limit peak loads

Mini-circuitbreakerMini-circuit breaker can encourage peak load reduction

kWh meter

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CASE STUDY - LOAD MANAGEMENT

Source: Schatz Energy Research Center

Voltage drops

• A 35 kW micro-hydro plant in Rukubji, Bhutan

• Lighting, TVs, rice cookers and water boilers are the common loads

As on many mini-grids, when load exceeded generation capacity, brownouts occurred

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GRIDSHARE LOAD MANAGEMENT TECHNOLOGY • Humboldt State University team, in

partnership with Bhutan Power Corporation and Bhutan DOE developed the GridShare.

• The GridShare, installed in each household, limits household load only during a brownout or voltage drop.

• The device is intelligent enough to detect rice cookers, and keeps them turned on for people to finish cooking their rice.

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GRIDSHARE LOAD MANAGEMENT TECHNOLOGY

Reduced spoiled rice

and

Residents stated:

“the grid is more predictable”

Electrical data indicated a reduction of over 90% in severe brownouts

Conclusions

Technology Application Impact

Interconnection relays mini-grid connect to main-grid

Lowers risk to developers of isolated mini-grids

Solar pico-grid Affordable pre-electrification

deliver small amounts of electricity, deploy quickly, inexpensively

ZigBee & GPRS internet connecctivity

monitoring of remote mini-grids

Lowers repair costs by catching problems early on.

SWER Low cost grid extension Reduced hardware cost

MCBs and GridShare Management of peak loads

Fewer brownouts

Chris Greacen

Palang Thai

chris@palangthai.org

www.palangthai.org