Charlie Salamone

Cape Power Systems ConsultingPresented at the Northeast Sustainable Energy Association’s Wind

Project Development Strategies for New England Workshop

3/7/06

Wind Generator Basics

Introduction

• Physical interconnection guide– Typical wind unit and utility characteristics

• Informal utility meeting– Information to ask about

• Do your homework– Energy Balance Analysis

Physical Interconnection GuideLarge plants must interconnect to the transmission grid (generally 20 MW or larger)

Small units (less than 20 MW) can connect to the distribution system through a step up transformer or (for much smaller units) through a customer service connection

Typical transmission voltages range from 115 kV to 345 kV

Typical distribution voltages range from

69 kV to 4 kV

Typical supply voltages range from

480 v to 120 v

Physical Interconnection Guide

• Output ranges– Many units available on the market with outputs ranging from 100 watts

to 3.6 MW

– Output voltages range from 12 volts dc (battery charging units) to 480 volts ac

– Units with output voltages of 240 volts ac are usually best for customer service connections

• Typical interconnection

components

Informal Utility Meeting• NOT required but can be helpful

– Conducted before any formal meetings or studies are performed– Will provide an overview of the process and economics involved

• What to ask:– Interconnection requirements and procedure description– Type of supply being provided (I.e. voltage, transformer size, shared

or single customer connection)– Availability of hourly use data in electronic format– Electrical facilities in close proximity to facility– Rates and tariffs applicable to generators (particularly stand-by rate

information)– Options for utility to purchase excess power– Options for sale of excess power into market system

Informal Utility Meeting

• What to expect:– Specific information concerning the process

and your service– General information concerning timeframes and

interconnection costs– Very general information concerning near by

facilities and their capacities

Informal Utility Meeting

• What not to expect:– Don’t expect any information to be binding or

guaranteed– Don’t expect any specifics concerning viability of an

interconnection point or associated costs– Don’t expect any advice or recommendations

concerning excess energy sales– Don’t expect any information that would require

studies or analysis– Don’t expect any recommendations concerning unit

sizes, designs or construction requirements

Do Your Homework• Energy use versus energy

output might be a simple calculation if you lived in Aruba– Wind blows between 10 and

15 mph 24 hrs/day almost all year long

– A 600 kw wind turbine could expect to produce 3,942 mwh annually (500x8760x.90) and reduce demands by at least 500 kw.

• US sited units aren’t quite so easy

Energy Balance Analysis

• Analysis that estimates energy costs and savings for a prior year based on actual customer use data and publicly available wind data – along with a bunch of assumptions.

• Customer use data– Use data is usually available from utility on an hourly

basis for an entire year in spreadsheet format– Some data manipulation is required to format data into a

monthly billing quantity compatible layout– Billing rates and monthly billing cycle dates are also

needed

Energy Balance Analysis

• Typical customer load profile data:

KW Load

0

100

200

300

400

500

600

700

1 40

79

118

157

196

235

274

313

352

391

430

469

KW Load

Energy Balance Analysis

• Publicly available wind data– Does not replace the need for site specific meteorological

data– May be used as a very general proxy for required data

prior to more in-depth analysis– Public sites where information on wind generation can be

found: http://seaboard.ndbc.noaa.gov/Maps/northeast_hist.shtmlhttp://cdo.ncdc.noaa.gov/ulcd/ULCDhttp://www.uwig.org/http://www.awea.org/faq/index.htmlhttp://www.ibew.org/articles/05journal/0509/p14_windmill.htm

Energy Balance Analysis

• Wind power generation calculation is highly complex but some simplifications can be made

• Translation of wind data into energy output will be required (this is the toughest part)

• Once data has been converted it can be merged with use data to derive an approximation of:– Energy use reduction and avoided energy

costs– Demand reduction and avoided demand

charges– Excess energy production and sales value

Example Wind Data ResultsWind Speed vs Output

100 KW Unit

05

1015202530354045

1

30

59

88

11

7

14

6

17

5

20

4

23

3

26

2

29

1

32

0

34

9

37

8

40

7

43

6

46

5

49

4

Intervals

(KW

- M

/S)

Wind Spd m/s Output

Energy Balance Analysis

• Results can provide a high level estimate of economic benefits versus costs of wind unit installation for your use characteristics

• Will only provide an indication of whether a more detailed analysis is worth the time and expense

Results of AnalysisWind Generator Estimate

1.5 MW Unit

-200

0

200

400

600

800

KW

Customer Load Wind Output Net Load/Gen

Use= 204972 kwhExport= 262 kwhReduced Use= 185764 kwhSavings= 19208 kwh