Distribution Companies –
Where the Network Meets the Load
Merlin Raab
Renewable & Energy Efficiency Sr. Consultant
Wisconsin Public Service Corporation
October 02, 2012
Agenda
•
•
•
•
•
Overview of Distribution Company
Distribution in the Value Chain
Responsibilities of Distribution Company
A Typical Day
Challenges
1
Distribution Companies – Where the Network Meets the Load
Electric Distribution Utility-1990
2
Distribution Companies – Where the Network Meets the Load
Electric Distribution Utility-2012
3
Distribution Companies – Where the Network Meets the Load
Physical Characteristics
• Electric distribution company begins at the
substation where the electricity is “stepped
down” to distribution voltage
• Lines feed out from the substation (typically in
the range of 7,200 to 25,000 volts)
• At customer locations, electricity is “stepped
down” again to a usable voltage – 120/240
volts for residential customers
4
Distribution Companies – Where the Network Meets the Load
The System Itself
• System has to be designed and constructed to:
– Ensure proper voltage levels
– Ensure equipment such as lines and transformers do not
overheat when peak flow occurs (hot summer day)
– Withstand the elements – weather, lightning, etc.
– Handle additional load such as new customers’ load or
existing customers adding load
• To do this, engineers develop computer models of the
distribution system to conduct load flow analysis
5
Distribution Companies – Where the Network Meets the Load
Distribution System Modeling / Analysis
Output from load flow analysis is used for:
–
–
–
–
–
–
–
–
6
Determining system efficiencies – present and future
Determining if equipment overload conditions exist
Determining high-loss line sections
System deficiencies during emergency switching or
temporary load transfers
Over-current protection plans
Feasibility of large load additions
Proper capacitor placement
Long-range planning – timing of substation reinforcements
Distribution Companies – Where the Network Meets the Load
Distribution System Modeling / Analysis
Increased emphasis on off-peak electricity usage
will change the shape of our typical load curve
and our computer model
– Electric vehicles charging during off-peak hours
– Customers shifting other appliance loads to
off-peak hours
7
Distribution Companies – Where the Network Meets the Load
Load Cycle of Substation Transformer
- Usually repeats every 24 hours
- Load fluctuates throughout the day
- Usually one peak period in the day
150%
Equipment Rating
100%
50%
Actual Load
12 PM
8
6 AM
NOON
6 PM
Distribution Companies – Where the Network Meets the Load
12 PM
Distribution in the Value Chain
• Supply produced at central plant or distributed
resources
• Central station supply is dispatched to the “Grid” and
then into one of three grids: ERCOT, WECC, and
Eastern Interconnection
• Transmission lines transmit energy to the market
• The market matches supply offers and load bids
• Control operators oversee transfer of energy to load
serving distribution companies
• Energy is “stepped down” to a distribution area and
then further “stepped down” to a customer site
9
Distribution Companies – Where the Network Meets the Load
NERC Interconnections
10
Distribution Companies – Where the Network Meets the Load
NERC Regions and Balancing Authorities
11
Distribution Companies – Where the Network Meets the Load
MISO Market in General
• Central bid/offer/settlement
MW
Schedules/Dispatch
MW Schedules
Bids
Offers
Generation
Generation
Generation
Generation
Generation
Generation
Generation
Generation
Distribution
Distribution
Distribution
Energy
Distribution
Distribution
Distribution
MISO Market
Energy
Dollars
Dollars
Prices
6,009 Generators
12
Distribution
Distribution Companies – Where the Network Meets the Load
264 Load Zones
Responsibilities of Distribution
Company – “Obligation to Serve”
• Retail Functions
• Meter to Cash
• Customer/Government
Relations
• Construction/maintenance
• Reliability
• Engineering studies
• Line clearance
• Storm restoration
• Power continuity/quality
• Safety
• Public
• Employee
13
• Economic Delivery
• Dispatch decisions
• “Cost per”
• Compliance
• PSC quality standards
• NERC reliability (Local
Balancing Authority)
• FERC
• OSHA
• Environmental and
Corporate Stewardship
• Environmental principles
• Hazardous waste/site runoff management
• Community outreach
Distribution Companies – Where the Network Meets the Load
A Typical Day in 1990
• Monitor system to ensure adequate amount of
generation to serve load; contract for additional
generation if needed
• Voluntary compliance with NERC & regional
reliability standards
• Build new and maintain distribution system
• Minimal number of customer-owned generators
putting power back to the grid
• Respond to power outages that are received via
phone from customers
14
Distribution Companies – Where the Network Meets the Load
A Typical Day in 1990 (continued)
• Customers who experience outage remain without power
until line electricians travel to the site to address cause
• Customer’s receive information on restoration times from
radio & TV
• Send out meter readers who bring back reads for use by
customer billing
• Customers generally not concerned with the timing of use
of electricity
• Appliances, such as dishwashers and refrigerators, run at
will
• The number of customers behind on their bill is small and
demographically homogeneous
15
Distribution Companies – Where the Network Meets the Load
A Typical Day in 2012
• Monitor system real-time and purchase power on the
MISO market to match load requirements or institute
demand control
• Limited customer-owned renewable generation putting
power onto the system requiring the distribution
company to adapt systems to handle it
• Systems used to proactively determine location of
outages and dispatch repair crews
• Customers receive restoration information via social
media
• Limited use of automated switches installed on
distribution system isolate faulted sections of line and
automatically restore power to a large portion of
customers without power
16
Distribution Companies – Where the Network Meets the Load
A Typical Day in 2012 (continued)
• Mandatory compliance with NERC & regional
reliability standards with threat of financial
penalties
• Meters read from a central location
automatically through communications network.
Customers have access to unbilled energy
consumption via web-portal
• Distribution system modernization technology
/smart meters allow customers to make full
advantage of time sensitive rates?
• The number of customers behind on their bill
growing and demographically diverse
17
Distribution Companies – Where the Network Meets the Load
Prices to Devices
Figure 1. Dynamic Energy Management Infrastructure for a Commercial Building
Source: EPRI
18
Distribution Companies – Where the Network Meets the Load
Challenges
Increased number of renewable source
generators on the distribution system & possibly
micro-grids
• Changes load flow analysis (computer model) due to
electricity flowing back to the system
• Requires modifications to equipment on those
circuits, such as over-current protection equipment
and conductors
• Requires modifications to operating procedures for
safety
• Net-metering: Who pays for maintaining the system?
19
Distribution Companies – Where the Network Meets the Load
Challenges
•Distribution companies will need to make significant
investments in equipment to accommodate increased
DG and increased off-peak usage
•Limited “Smart System” benefits to rural customers
•Regulatory Uncertainty regarding “Smart system
investments”
•Who bears the risks?
•Opt out vs. Opt. in pricing options
•Security & privacy issues
•EMF concerns
20
Distribution Companies – Where the Network Meets the Load
Challenges
• Customer
• Keep costs down (low rates) amid cost pressure
• Help understand rate vs. bill – energy optimization
• Shareholder
• Maintain attractive, risk-adjusted return
• Employee
• Graying of industry / training / retention /
cost reduction
21
Distribution Companies – Where the Network Meets the Load
22
Distribution Companies – Where the Network Meets the Load