1. Microgrids - Opportunities and Challenges
Giri Venkataramanan
University of Wisconsin - Madison

2. Microgrids - Objectives
What is a microgrid?
What is the status of microgrid technology?
How will it impact our future?
What are the challenges?
What are the opportunities?
How does it fit with sustainability goals?

3. Dominant Electricity Paradigm
Central generation – Variety of prime sources
Bulk transmission – HVAC/HVDC
Distribution – Medium/Low voltage, single and three phase
Largely regulated revenue processes at the retail level
Traded at bulk utility level and very large customer level

4. Dominant Electricity Paradigm
Top-down hierarchal control
Complex and large synchronized system
Supply (Generation) and Demand (Loads) have to be matched within short intervals of time
Loss of system interconnectivity requires days and weeks to bring back to synchronims

5. Challenges in Established Markets
Habit of plenty
Aging public service infrastructure
Stingy investment community
Uncertain economic projections
Poor resilience
Slow growing electricity needs
May be shaped by EV adoption
Changing demographics

6. Challenges in Growing Markets
Large gap between supply and demand
Insufficient infrastructure
Inadequate investments
Challenging operational arrangements
Uncertain and inefficient responsibility centers

7. On the ground - India
Traditional generation growing, but cannot keep up with demand growth
Established wind integration and emerging PV integration
Load shedding, outages, brown-outs…
~$ 2Bn/year market for reciprocating engines
~$1.5Bn/year market for UPS systems
~$1.5Bn/year market for back-up inverter systems
Rural/Urban divide
Will a reliable grid ever reach the unserved and underserved 100s of millions?

8. Challenges in Unserved Markets
Practical absence in demand
Primitive infrastructure
Unfamiliar economic territory
Inefficient investment models
Challenging operational arrangements
Uncertain and inefficient responsibility centers

9. Mobile phone penetration
Figure 5
Scatter plot of (A) infant mortality and (B) life expectancy vs consumption per person
Drawn from data compiled in references 30 and 31. Symbol sizes are proportional to country populations. Kg of oil equivalent=energy equivalent to that produced by combustion of kg of oil.

10. Mobile phone expenses in Africa
Figure 5
Scatter plot of (A) infant mortality and (B) life expectancy vs consumption per person
Drawn from data compiled in references 30 and 31. Symbol sizes are proportional to country populations. Kg of oil equivalent=energy equivalent to that produced by combustion of kg of oil.
From: Alison Gillwald & Christoph Stork
ICT access and usage in Africa Vol Policy Paper 2

11. How do fixed lines fare? If mobile phones can penetrate the market
Top down approaches will not take us there
From: Alison Gillwald & Christoph Stork
ICT access and usage in Africa Vol Policy Paper 2
If mobile phones can penetrate the market
Electricity can also…

12. Source/storage integration
Micro Turbine
Wind Turbine
PV Array
GenSets
Interconnect
Switch
Fuel Cells
Plug-In Hybrid
Battery Storage
Flywheel
Microgrids provide a framework for integrating large amounts of distributed sources into the power grid
Particularly important for renewable energy sources
Microgrids open the door to significant system efficiency improvements by integrating with system energy needs

13. MicroGrid Features Clustering sources with loads
Smooth transfer between grid
and island modes
No explicit communication
system
Peer-to-peer source model
Plug & Play model
CHP to improve efficiency
Scalable system
PCC
Switch DR DR DR
Local
Loads
Grid
Third party
Loads

14. UW

15. Wisconsin μgrid Technology Base
3 MW Santa Rita Cor. Facility Test Site
100 kW AEP/CERTS Microgrid Test Site
UW-Madison faculty have been developing robust microgrid technology during past 10+ years

16. Viability of microgrids employing diverse sources
What do we know?
Viability of microgrids employing diverse sources
Classical synchronous machine
Squirrel cage machine + active excitation
Inverter based 1f and 3f
Careful application of control
Compatibility
interruptible grid
storage
current fed systems (PV, Wind)
At least one grid forming unit per microgrid
hierarchal topology
optimizing dispatch

17. AC microgrids

18. DC microgrids

19. Hybrid microgrids

20. Nested microgrids

21. What do we not know?
Definitive stability studies
Strategies for matching supply and demand
Bidirectional power flow at PCC
Anti-islanding at the PCC
Protection/coordination challenge
Who is responsible
Metering, regulatory and commercial aspects

22. What is going on today?
Connecticut governor announced a project to develop microgrids
DoD has initiated large scale programs for forward operating bases

23. What does this mean for sustainability?
Lowest cost opportunity
Fuel neutral technologies
Microgrid business package
Modular design of generation/distribution/operation components
Metering/revenue packages
Business model development
Unintended consequences