Control Strategies for Resilience Enhancement in Networked...
Transcript of Control Strategies for Resilience Enhancement in Networked...
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Control Strategies for Resilience Enhancement in Networked Microgrids
Professor Mohammad ShahidehpourGalvin Center for Electricity Innovation
Illinois Institute of Technology
Outline
• Distributed Power Systems
• Applications of Distributed Power Systems
• Microgrids in Power Systems
• Networked Microgrids
• Conclusions
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Edison Transformation
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Building Block of Smart Grid: Microgrids
Locally integrate renewables and other distributed generationsources and provide reliable power to customers.
Protect critical infrastructure from power outages in theevent of physical or cyber disruptions in the bulk electric grid.
Ensure that critical operations can be sustained duringprolonged utility power outages.
Electric power grid will be the “grid of grids” in the future.
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Solar Canopy, Flow Battery
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Loop‐based microgrid topology introduces additional benefits in enhancing the reliability and resilience of energy supplies.
AC/DC Nanogrid at IIT
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Multi‐Microgrid In Chicago
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Frequency Domain Analysis
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IndependentOperation of Microgrids
CoordinatedOperation
Loci of dominant eigenvalues when ‐P droop gains increase
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Weather‐Related Power Outages
• The climate change has increased both the frequency and the severity of adverse weather throughout the world.
• There were as many as 10 times more massive blackouts each year in the 2000s compared to those reported each year in the 1980s and early 1990s.
• In 2018, the United States suffered six weather‐related disasters, including 4 severe storm events and 2 winter storm events, each of which incurred economic losses exceeding $1 billion.
Blizzard Hurricane
Flood Earthquake
Emergency Microgrid Operations
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Normal Degraded Normal
Extreme event occurrence
Conditiondeterioration
Restorationinitiation
On Outage Degraded
Restorationcompletion
Before During AfterTime
Normal Degraded Normal
Extreme event occurrence
Disconnectionfrom main grid
Sustained
Before During AfterTime
Reconnectionto main grid
withoutMicrogrid
withMicrogrid
Time
Robustness
Preparedness
Recoverability
Rapidity
Before During After
Perception Comprehension Projection
Situational Awareness
Elements of Resilience
Extreme Events
Hurricane Flood Solar Flare... Earthquake Cyberattack
Responsiveness
Survivability
Distributed Power System Operation: Division and Unification
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Designated MC
... ... ......
... .........
(a)
(b)
...
Data FlowDERCoordinator
MG0 MG1
Utility
AC main bus
IC1
MGj
ICj ICN
MGN
MC0 MC1 MCj MCN
CMC
Utility feeders
IC0
• The networked microgrid system can switch between two distinct modes for enhancing the power system resilience by exploiting the system operational flexibility in critical conditions.
‐ The division mode helps the networked microgrid system prepare more adequately for perceived extreme events by ensuring the operational flexibility of individual microgrids. In division mode, each microgrid can be islanded from or resynchronized with the system with limited impacts on the remaining system.
‐ The unification mode allows the system to adapt to changing conditions and incidental disturbances by the cooperation among participating microgrids. Accordingly, the operational flexibility of the entire system is improved as available resources are shared among participating microgrids.
‐ The switching between the two modes does not require additional communication and control infrastructures, indicating that the power system resilience is improved in a cost‐effective way
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Division and Unification of Networked Microgrid
Dynamic Islanding Schemes
• In each aggregated island, interconnected microgrids are enabled totransact energy directly and flexibly for surviving utility grid disruptions.
• The islanding scheme could be adjusted on an on‐going basis accordingto temporal operation characteristics of individual microgrids and theprogression of failures in the utility grid.
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Upstream Network
Microgrid 1 Microgrid 2
Microgrid 3 Microgrid 4
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Single Island
Upstream Network
Microgrid 1 Microgrid 2
Microgrid 3 Microgrid 4
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Island 1
Island 2
Upstream Network
Microgrid 1 Microgrid 2
Microgrid 3 Microgrid 4
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Island 1 Island 2
Island 3 Island 4
Decision for Optimal Islanding
• Transactive energy facilitates the formation of aggregated islands ofmultiple microgrids, boosting the flexibility of the islanding process.
• DSO determines and triggers the islanding of networked microgrids in aholistic manner by considering the role of transactive energy, instead offorcing islanded microgrids to rely solely on themselves.
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Flexible Energy Trading
Upper-Level Problem (DSO)
Determine: Optimal Islanding Scheme
Constrained by: Security of Distribution System Operations
Lower-Level Problem (Networked Microgrids)
Determine: Minimized Generation and Load Shedding Costs
Constrained by: Transactive Energy Principles
Distribution System Configuration
Total Operation Costs
Two‐Layer Decision‐Making Scheme
Upstream Network
Microgrid 1 Microgrid 2
Microgrid 3 Microgrid 4
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Island 1 Island 2
Island 3 Island 4
The networked microgrid system is composed of three interconnected microgrids, including MG1 (containing DERs 1‐3), MG2 (containing DERs 4‐7), and MG3 (containing DERs 8‐9). The loads are located at Buses 1, 9, 12, 14, 18, 21, 25, 27, 30, and 32, respectively. The corresponding communication network is depicted, which is a fully connected graph. The rated frequency and voltage are set as 60Hz and 1 p.u.
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Case Study
1 2 3 4 5 6 7 8 9 10 11 12 13 14
23 24 25 26 27 28 29 30 31 32 33
15 16 17 18
DER1
S12
19 20 21 22
S23S13
DER2
DER3
DERs Loads Closed switch Opened switch
DER7DER6
DER4 DER5
DER8 DER9
MG1 MG2
MG3
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6 5
1
2 3MC1
4
8 9
MG1
MG2 MG3
DER Pinned DER
Pinning control signal
MC
MC3
MC2
Intra-communication linkInter-communication link
33‐bus distribution system composed of three interconnected microgrids
Communication network of the networked microgrid system
(1) At t = 10s, the networked microgrid system runs in division mode when the system operation is divided into several self‐controlled entities with different active power sharing strategies while all the MGs are still interconnected in terms of power and communication networks;
(2) At t = 30s, an additional load (135 kW+j15kVar) is added to the MG1 and an additional load (120 kW+j15kVar) is added to MG2;
(3) At t = 50s, MG2 is islanded from the distribution network and operated in islanded mode;
(4) At t = 70s, MG2 is resynchronized with the distribution network.
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Case Study: Division Mode
10 20 30 40 50 60 70 80Time(s)
0.5
1
1.5
2
10 20 30 40 50 60 70 80Time(s)
59.4
59.6
59.8
60
60.2
60.4
Freq
uenc
y (H
z)Po
wer
Sha
ring
(miP
i)
(a)
(b)
DERs in MG1
DERs in MG2
DERs in MG3
DER1DER2DER3
MG1:DER4DER5DER6DER7
MG2:DER8DER9
MG3:
DER1DER2DER3
MG1:DER4DER5DER6DER7
MG2:DER8DER9
MG3:
10 20 30 40 50 60 70 800.9
0.95
1
1.05
Time(s)
Vol
tage
(p.u
.)
(c)
DER1DER2DER3
MG1:DER4DER5DER6DER7
MG2:DER8DER9
MG3:
(5) At t = 90s, the networked MGs system is switched to the unification mode which allows all DERs in participating MGs work together for maintaining the unified active power sharing and rated operating frequency;
(6) At t = 110s, an additional load (150 kW+j15kVar) is added to the distribution network;
(7) At t = 130s, DER9 is disconnected from MG2 with the loss of communication links 3‐9 and 8‐9;
(8) At t = 150s, DER9 is reconnected to MG2.
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Case Study: Unification Mode
80 90 100 110 120 130 140 150 160Time(s)
1
1.5
2
80 90 100 110 120 130 140 150 160Time(s)
59.6
59.8
60
60.2
60.4
Freq
uenc
y (H
z)Po
wer
Sha
ring
(miP
i)
(a)
(b)
DER9 is disconnected
DER1DER2DER3
MG1:DER4DER5DER6DER7
MG2:DER8DER9
MG3:
DER1DER2DER3
MG1:DER4DER5DER6DER7
MG2:DER8DER9
MG3:
80 90 100 110 120 130 140 150 1600.9
0.95
1
1.05
Time(s)
Vol
tage
(p.u
.)
(c)
DER1DER2DER3
MG1:DER4DER5DER6DER7
MG2:DER8DER9
MG3:
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• The myriad of extreme events such as severe weather conditions and potential cyber‐attacks have posed great challenges to the power system resilience.
• The proliferation of microgrids, which could play a key role in resilience enhancement, has changed the paradigm in power system operations.
• The networking of geographically close microgrids is a promising and all‐encompassing solution to accommodate more DERs and further enhance the power system resilience.
• Flexible control strategy could enhance the networked microgrid system resilience against extreme events which is essential for the operation of power distribution systems.
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Conclusion
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Thanks
Dr. Mohammad Shahidehpour