Microgrids - Opportunities and Challenges Giri Venkataramanan University of Wisconsin - Madison giri@engr.wisc.edu

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?

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

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

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

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

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?

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

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. http://www.floatingsheep.org/2011/01/map-of-per-capita-mobile-phone.html

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: www.researchICTafrica.net, Alison Gillwald & Christoph Stork ICT access and usage in Africa Vol 1 2008 Policy Paper 2

How do fixed lines fare? If mobile phones can penetrate the market Top down approaches will not take us there From: www.researchICTafrica.net, Alison Gillwald & Christoph Stork ICT access and usage in Africa Vol 1 2008 Policy Paper 2 If mobile phones can penetrate the market Electricity can also…

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

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

Microgrid @ UW

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

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

AC microgrids

DC microgrids

Hybrid microgrids

Nested microgrids

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

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

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