Project 1.4
Operational Strategies and Storage
Technologies to Address Barriers for Very High
Penetration of DG Units in Intelligent Microgrids
Dr. Géza Joós
Student: Michael Ross
www.smart-microgrid.ca
Purpose and Challenges
• Create a general framework for energy
management of Microgrids with large
amounts of renewables
– Controlling a Microgrid with a high level of
uncertainty and variability (e.g., stochastic
nature of renewable generation).
• The methodology will be implemented for
different renewable energy portfolios and
power system configurations
– Developing an operation strategy that maximizes
economic considerations
– Incorporating various DER
www.smart-microgrid.ca
• Identify barriers associated for large number of renewable DGs
& research energy management strategies
2011
2012
• Establish performance metrics considering cost optimization
• Evaluate Storage technologies, modes of operation, ancillary
service functions and values
2013
2014
• Research and develop controlling strategies and algorithms
2015
• Evaluate performance of strategies
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Cutting edge
research
Industrial
experience
Enhancement
for Canada’s
future power
system
www.smart-microgrid.ca
Projects 2.2 & 2.4
Energy & supply
security and
Integration design
Projects 1.1 & 1.2
Projects 3.1 & 3.2
Control, operation
and power
management
Communication
infrastructure and
Grid integration
Project 1.4
Operational
Strategies & Storage
Technologies for a
large penetration of
renewable DGs
www.smart-microgrid.ca
Barriers for Large Number of
Renewable DGs
•
•
•
•
•
•
Bi-Directional Power Flow
Protection Coordination
System Grounding Issues
Unintentional Islanding
Power Balancing
Ancillary Services
www.smart-microgrid.ca
Bi-directional power flow
• There may be times of high input power
and low consumption, and other times of
high demand but low generation.
– This is a problem since the voltage regulation is
difficult to control (voltage rise effect).
• Power can be exported as well as imported
• A fault on a lateral feeder can be “seen” on
a healthy feeder, causing it to trip
Source: NRCan
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Protection Coordination
• Loss of coordination (fault currents can be
larger, which means that some protective
equipment can trip simultaneously)
• Loss of sensitivity (if the fault is located
downstream of the DG, the utility might not
be able to detect that a fault occurred).
• Nuisance fuse blowing
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Protection Coordination
• Fault currents can vary widely based on
whether microgrids are connected to the
grid, or disconnected
– Protection equipment must know when the
microgrid is isolated or grid-connected
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System Grounding Issues
• Grounding issues of the DG and
interconnecting transformer can cause
either overvoltages in a line-single toground fault, or it can increase the short
circuit current by allowing a path for zerosequence currents to flow
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Unintentional Islanding
• The DG can reconnect out of phase with the
utility
• The DG can be damaged in a fault condition
• There is a risk to personnel who may
operate on an energized feeder
• DGs may not have voltage or frequency
support
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Power Balancing
• Load following controls must be in place
when the DG is large enough such that
many loads on the feeder are supplied with
power from the DG, or when operating as a
microgrid.
• This is particularly difficult with renewable
DGs since the input power is intermittent.
www.smart-microgrid.ca
Ancillary Services
• The feeder cannot rely on generator inertia
(if interfaced through power-electronics)
with dynamic changes in load
– Must rely on other sources (energy storage, for
example) to ensure inertial frequency response
for the initial energy balance when a new load
comes online/offline
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Current Interconnection
Standards
• IEEE 1547
• Requirements for the Interconnection of
Distributed Generation to the Hydro-Quebec
Medium-Voltage Distribution System
• BC Hydro Interconnection Requirements for
Power Generators
• Hydro One Distributed Generation Technical
Interconnection Requirements
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Energy Management Strategies
• Load curtailment
– Demand response
– Direct load control
• Generation curtailment
– Including dump loads
• Energy Storage Systems
–
–
–
–
Batteries
Flywheels
Supercapacitors
Etc.
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Gaps:
- Other barriers for high
penetration renewable DGs?
- Other interconnection
standards?
- Energy management strategies?
www.smart-microgrid.ca
Project 1.4
Operational Strategies and Storage
Technologies to Address Barriers for Very
High Penetration of DG Units in Intelligent
Microgrids
For further information contact:
Michael Ross
michael.ross2@mail.mcgill.ca
www.smart-microgrid.ca