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.

CO

NF

IDE

NT

IAL

FO

RD

ISC

US

SIO

NP

UR

PO

SE

SO

NLY

PA

GE

4O

F4

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)

CO

NF

IDE

NT

IAL

FO

RD

ISC

US

SIO

NP

UR

PO

SE

SO

NL

YP

AG

E7

OF

40

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.