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Non-Synchronous Microgrids
for Resiliency and Utility Integration
Shalom Flank, CTO & Microgrid Architect
October 10, 2013
RPI WORKSHOP ON MICROGRID TECHNOLOGY & APPLICATIONS
What’s Different about
Non-Synchronous Microgrids?
Utility Integration: Connect Unlimited DG Anywhere
Autonomy: Always Islanded, Yet Always Connected
Generators: Stable Operation for Multiple Distributed Resources
Grid Resiliency: A Benefit, not a Burden
Cost: Pre-Packaged Solution at Lower First-Cost
Radial & Networked Grids:
DG Can Exceed Fault Current Limitations
For a parallel generator interconnection, either rotating or inverter based, there will always be some fault current contribution to an existing system, even if the net energy is consumed on-site and not exported to the grid.
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0What if DG and Grid Power were not
Synchronized with One Another?
As long as no net energy flows backwards into the host utility, the microgrid appears as a load to the feeder, and so any amount of generation can be connected
Back-to-Back Inverters: Integrate Multiple
Sources with a Common DC Bus
The Consequences of Delayed Islanding of On-Site Power:
Bradley Airport October 2011 Power Outage
On-Site CHP System Took Many Hours to Island
FAA Report on Bradley Outage:…20 inches of snow fell at Bradley International. It caused a widespread commercial power failure, which caused communications problems in the airport. Luggage belts and cargo belts and elevators stopped working. There was difficulty refueling airplanes. There was difficulty de-icing aircraft. We all know that when you can’t de-ice your aircraft in those conditions, you might as well weld your plane to the ramp. You’re not going anywhere.
Source: http://www.faa.gov/news/speeches/news_story.cfm?newsId=13252
Not the only recent outage at Bradley:“A power outage occurred on March 6 on 8:15 p.m. that was caused by a blip on the C L & P grid and a switch that did not operate as it should have at the Airport's cogeneration plant.”(Bradley Airport Minutes, March 2011)
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Islanding the UC San Diego Microgrid:
September 2011 SDG&E Outage
3:40pm
Loss of Utility Grid. lmporting-10.5MW;
Total Campus Load- 37.5MW. Total loss of
power to entire campus
3:40 pm -
4:30pm
Stabilize Central Plant Equipment via Diesel
Generation; Assess Situation; Natural Gas
available at normal pressure; Begin Black
Starting Cogen Plant
6:30 pm-
7:00 pm
Unit 1 online (13MW capacity); Begin adding
campus load manually; Unit 1 tripped on
boiler water safety; Restarted and stabilize
turbine at 11 MW
7:00 pm-
8:45 m
Start Central Plant Steam Turbine Generator,
Steam Turbine Chiller and Unit 2; Bring Unit
2 online; Generators do not parallel, both
units trip; Total loss of Power to entire
campus.
8:45pm-
9:45pm
Restart Unit 1 and Bring Online; Restart Unit
2, Steam Turbine Generator and Steam
Turbine Chiller; Parallel Manually and
Stabilized at approx 6MW each
9:45 pm-
10:30pm
Manually close distribution breakers, Campus
stabilized at approx 27MW
1:30am
Sept 9th
Utility Grid available and stabilized;
Manually Paralleled to Utility Grid; Released
all controls to automatic
GridLink™
Easy Integration of Multiple Sources of Local Power
Fuel Cells
Existing Backup Gensets
Local Distribution Microgrid
GeothermalEnergy Storage
Parking Canopy PV
Combined Heat & Power
Wind Turbines(Bldg Integrated & Remote)
Incoming Utility Power
Grid Resiliency:
A Benefit, not a Burden
Zero fault current / voltage instability / penetration depth issues
Well-behaved sinusoidal load with limited harmonics
Ride-Through: Generators don’t trip off when needed most
Loads de-coupled from distribution system
Real-time adjustment of export levels, with hard limits
Ancillary services: dVAR, frequency regulation
Export into sectionalized grid during outages
GridLink: Packaged Solution for
Non-Synchronous Microgrids
Energy Improvement Districts
Patented Non-Synchronous interconnection technology enables an always-islanded
Microgrid with the ability to plug and play multiple distributed energy resources and to
provide uninterrupted power during utility grid power outages at below grid rates, with
governance by the Microgrid energy users.
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