-Distributed Generation -
A Reliable Power Solution For The Digital Age?
Dustin T. Smith
Project Development
Manager
Sure Power Corporation
2002
Power System 2002 Conference
Impact of Distributed Generation
Clemson, SC
March 13-15, 2002
Today

Today: Key macro-economic trend – Everything is digital (digital economy)



Components that have been addressed: IT (networks &
software)/Telecommunications (networks & software)/Equipment Manufacturers
(reliability of components). Components that have not been addressed: Power
What Do We Want To Accomplish?

Collectively have a better understanding of Applying DG to Mission Critical
Facilities.

Reinforce the definitions of common metrics.

Challenge barriers to wide spread use of Distributed Generation. Encourage
evaluating Distributed Generation as an option.
Topic Items

Appropriate Use Of Metrics – Reliability vs. Availability vs. Quality

Power Issues Of The Digital Age

Critical Elements Of DG High Availability Power – Mission Critical Applications

Example Schematic - DG Mission Critical Application

Summary - Concepts To Remember
Power Issues Of The Digital Age


Electric Utility

Built for the Industrial Age (light bulbs and motors).

Ability to support Mission Critical facilities is different in every location.
Facilities

Facilities supporting digital commerce are a critical component of the final
product (Integrate the value of Availability into Marketing Plan).


Demands – Volume, Availability & Quality


Integration of Product Marketing and Facilitates Planning/Design
Groups in conjunction with the Business Plan – Complex Project.
Scaleable, High Availability (5 9s or greater), CBEMA grade (IEEE 4461987) power.
Vulnerabilities - Complex systems are much weaker than their weakest link.

Digital equipment power sensitivity (example: eight milliseconds
outside voltage curve for microprocessors & more than a 20% voltage
deviation for four cycles for semiconductor fabrication = SYSTEM
FAILURE). Even short down times equals huge losses. On-Going
operations & maintenance are crucial.
Quality - CBEMA Curve
Typical Design Goals of Power Conscious Equipment
Manufacturers - CBEMA CURVE
(IEEE 446-1987)
400%
Voltage Excursions (%)
Nominal = 100%
350%
300%
250%
Half Cycle
200%
150%
100%
50%
0%
0.001
0.01
0.1
0.5
1
10
Time in electrical cycles - Logarithmic Scale
100
1000
Reliability
Reliability

The Probability that a system or even a component will operate for a given
period of time. Quality is a component of this metric.

Over time, reliability tends toward 0 (all components eventually fail).

For complex systems: Mission length must be known and is most
useful for analysis of missions during which equipment may not be
repaired or down for maintenance (missions of shorter duration).

R = 1 - Pf (Probability of Failure)
Over Time - All Components Fail
1
Reliability

0
0
0.5
1
1.5
2
2.5
Time
3
3.5
4
4.5
5
Reliability Example
Reliability of Emergency Diesel Generators
1
0.95
0.9
0.85
0.8
0.75
1/2 hour
8 hours
24 hours
– Emergency Diesel Engine Generator Power System Reliability 1987-1993
Grant, G.M., et. al., Idaho National Engineering Laboratory, INEL-95/0035,
February 1996
Availability

Availability (Unavailability=Q=1-A)


The probability that a system will function at a future instant in time. Quality and
Reliability are components of this metric.

Most useful in the analysis of complex, repairable systems with longer
mission durations (does not necessarily require defined mission
length).

Probabilistic Risk Assessment – Most useful tool in defining
Availability (Redundancy/Spare Parts Inventory/SLAs/Staffing).

Utilizes historical performance data for individual components.

Provides specific probability of system availability in the future.

Over time, calculated results have been extremely accurate (I.e.
nuclear industry).
Availability is the most useful metric for identifying power performance
parameters for mission critical applications.

According to experts in the science of Probabilistic Risk Asseement1,
achieving availability levels (in practice) above four 9s (99.99%), likely
requires on-site distributed generation.
[1] Steve Fairfax, President of Mtechnology, Saxonville, Massachusetts, USA
Application of the Nines
The PRA gives us an Availability Design Criteria. How do we apply it?
In The Digital Economy, Unavailability (1-Availability)
does not equal Down Time (Facility outage may be a magnitude
longer than the original power outage).
Nines
"one nine"
"two nines"
"three nines"
"four nines"
"five nines"
"six nines"
Availability Unavailability
90%
99%
99.9%
99.99%
99.999%
99.9999%
10%
1%
1.0.E-3
1.0.E-4
1.0.E-5
1.0.E-6
Downtime
876
87.6
8.76
53
5.3
32
hours
hours
hours
minutes
minutes
seconds
We must convert the system Availability/Unavailability
to a specific Probability of system failure!
Availability & Probability of Failure
Cumulative Probability
of at least 1 Failure
100
90
Assumptions:
80
16 hour mean time to repair
70
60
20-year operating life
50
40
30
20
10
0
99% 99.9% 99.99%
10-2 10-3 10-4
99.999%
10-5
Availability
Unavailability
99.9999%
10-6
The Traditional Approach
Utility
Substations
Normal
Load
HVAC
Systems
Essential
Load
Standby
Gensets
Note: System availability 99.9% to 99.99%
- Grid is prime source of power
- Battery is short-term backup
- Gensets are secondary source of power
UPS
System
Battery
Backup
Critical
Load
High Availability DG System
Chiller System
Normal
Load
Utility
( if available )
On-Site
Power
System
Note: Desirable System availability: 99.9999%
- Prime source of power
- Grid is secondary source of power
Essential
Load
Critical
Load
Critical Elements Of DG High Availability

Basic elements of a high availability power system:

Redundancy


Energy Storage


Maintains power flow to the critical load while additional power
sources are dispatched during prime mover failure.
Switching


Allows system to operate when individual components fail.
Detects failures in components (or even subsystems), and connects
replacements (very complex and difficult).
All High Availability Designs must use these elements to achieve near-perfect operation
with imperfect, real-world components.

Probabilistic Risks Assessment is a proven tool for determining the best
balance of these elements and effecting the real-world system performance.

Mission Critical DG systems must be designed from the ground up with the
goals, objectives and elements of High Availability in mind, not modified afterthe-fact (pound-to-fit).
Additional Elements Of DG High Availability

Additional system performance requirements include:

Precise end user goals and objectives identified.

No single Point of failure


Independent redundant power paths


All generation available to all of the load, all of the time without
switching.
No generation inter-dependencies


Example: RAID (Redundant Array of Independent Devices)
Eliminate all potential cascade failures
Design must allow for maintenance and repair (both routine and emergency)
without disruption of power to the critical loads.
Benefits of DG In Mission Critical App.

Benefits of Distributed Generation in Mission Critical Applications

Dedicated operations and maintenance staff

Allows End User to manage their overall operational risk by allowing experts to
handle the on-going production and delivery of Mission Critical power

True system High Availability

Efficiency (CHP Process)

Reduction in Environmental emissions

Capitol management (paying for on-site assets, not the Utilities transmission
lines

Security

Autonomy/Control
Concepts To Remember

“Availability” is the most useful metric for evaluating the application of Distributed
Generation power systems with respect to Mission Critical Facilities.

A formal, reviewable, rigorous design process such as Probabilistic Risk
Assessment will dictate a design that ensures actual system performance meets
the End Users long term system performance expectations (as well as meet
business plan marketing objectives).
Table Reference: A Technical and Market Assessment of Premium Power in the Haverhill
Cyber-District, Prepared For: Massachusetts Collaborative, Prepared By Planet-TECH
Associates, January 2002
Concepts To Remember Continued

“Availability” - Continued

These types of systems cost lest than the systems that do fail.
Table Reference: A Technical and Market Assessment of Premium Power in the Haverhill
Cyber-District, Prepared For: Massachusetts Collaborative, Prepared By Planet-TECH
Associates, January 2002

Once a system achieves High Availability in design, real-world limits such as
common cause failures can be addressed.
First National Bank of Omaha
[Only DG - Mission Critical Installation with 3rd Party PRA Certification (Availability Higher than Grid + Back-up]
© Copyright First National Bank of Omaha 1999
The reliability of the ‘six 9s’ computer grade electricity that Sure Power
delivers isn’t a luxury for us at First National Bank of Omaha, it’s a critical
difference over existing power arrangements that will substantially increase
our computer uptime. The result is a tremendous leap in our competitive
advantage. With Sure Power, First National can raise our customer’s service
expectations while generating higher revenues.
United States Patent 6,288,456 B1
Date of Patent September 11, 2001
Dennis C. Hughes
Director of Property Management
First National Buildings, Inc.
The End
“Powering Mission Critical Enterprises”
Sample Sure Power Solution
Sure Power System Rendering