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Microgrid Deployment to Benefit DER Integration
Presented By
Ratan Das Vahid Madani Sakis Meliopoulos
i-PCGRID Workshop 2017, San Francisco, CA USA, March 29 - 31
05 April 2017 2
Evolving Electric Grid
Active Distribution Network
DER Integration Challenges
Asynchronous Microgrid Interconnection
Microgrid Benefit for DER Integration
Centralized Protection & Control (CPC)
Microgrid Management System Using CPC
Estimation Based Protection & Centralized Grid Protection
Summary
Outline
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Evolving Electric GridPower Plants
Smart Grid functionality restores the balance Hydro Power Plants
Nuclear Power Plants
Natural Gas Generators
Transmission Lines
Distribution Substations
Plug-in Electric Vehicles
Rooftop Solar
Solar Farms
Wind Farms
Electric Grid Customers
Utility-scale Storage Distributed Storage
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Active Distribution Network
GS
Generators
Transformers
Transmission Lines
Transformers
Distribution Lines
Sub-transmission Lines
Transformers
Utility 1 Control Center
Utility 1/A Distribution
Control Center (DMS)
Generation
Sub
Transmission
SubUtility 2 Control Center
ISO
DERDER DER
DER
PV
ES
EV
Distribution
Sub
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Active Power Control Frequency
Reactive Power Control Voltage
Voltage and Frequency Ride-through
Protection
Power Quality Issues• Rapid voltage Changes and Flicker• Harmonic current and voltage distortion• Temporary/transient overvoltage• Supraharmonics (2 kHz -150 kHz) and Interharmonics• Changes and multiplicity of resonance frequencies due to the large
capacitor in the DER inverter on the system side
DER Integration Challenges IEEE 1547 StandardIEEE 1547 Standard
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Microgrid Definition
A group of interconnected loads and distributed energy resources (DER) with clearly defined electrical boundaries; which can be operated as a single standalone controllable entity or can be operated in either grid connected or island mode. Microgrids are typically connected to distribution or sub-transmission voltage levels. The maximum capacity of the microgrid is limited by the associated equipment current and operating voltage ratings. Some examples of microgrid include university campus, industrial parks, small community, defense establishment, and medical facilities with ratings from kW to MW range.
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Microgrid Example
From IIT Website
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Asynchronous Microgrid Interconnection
Microgrid11
Microgrid12
Microgrid13
Microgrid1n
ActiveDistribution Network 1
‐‐‐‐‐‐‐‐
back-to-back dc
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Back-to-back dc main grid connection (asynchronous)
No resynchronization issues
Active power control within the microgrid• Manages frequency within the microgrid
• Opportunity to define new frequency profiles in PQ standard
Reactive power control within the microgrid• Manages voltage profile within the microgrid
• Opportunity to define new voltage profiles in PQ standard• No reactive power management issue within a dc microgrid
Real and Reactive power control at PCC (service to grid)
Microgrid Benefit for DER Integration
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Centralized Protection and Control (CPC)
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Microgrid Control (IEEE 2030.7 & 2030.8)– Active Power Control
– Reactive Power Control
Microgrid Protection – Directional overcurrent
– Over/under - voltage & frequency
– Dynamic State Estimation based protection
– Assist Differential protection of feeders
Microgrid Management System Using CPCRD1
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Estimation Based Protection and Centralized mGrid Protection
Limitations of Legacy Protection as Applied to Grid– No separation between fault and load current
(especially in islanded mode)– Inverter based systems– Asymmetries and grounds
Characteristics of Grid– Low Voltage – inexpensive sensors– Confined Geographical extent– Ideal for application of estimation based protection– Supervision of protection infrastructure (Grid
Centralized Protection)
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Dynamic State Estimation Based Protection• Setting-less protective relay
• Sampled Value based dynamic state estimation
• Fast fault detection and locating (sub ms)
• High Impedance Fault D&L
• Power Quality Analysis
Estimation Based Protection of Grid Components
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Centralized Grid Protection and Control
Low cost merging units (600V class)
Each component is protected with a setting-less relay (EBP)
Each EBP is supervised by a centralized Grid Protection system, GridCP.
GridCP provides full state and model of the Grid at each cycle for full state feedback control.
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Time domain model and estimated data are converted into phasor domain for upstream use.
Measurement data are streaming from merging units to relays.
Dynamic State Estimation based protection (a.k.a. setting-less protection) for each protection zone (for example, circuit, transformers, PV, etc.).
Merging Unit provide GPS synchronized measurements.
Validated measurements (and model parameters) are streaming to microgrid control center (CC). If necessary validated data are also fed back to the setting-less relays.
The model and measurements for entire Gridare used to perform Grid wide state estimation. The procedure identifies bad measurements as well as the root cause of bad measurements. Bad measurements are removed, root causes are reported to microgrid control center (CC).
Centralized Grid Protection and Control
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μGrid Control and OperationsModel based ControlBasic Approach: Full State Feedback Control (requires new generation dynamic state estimator)
Key Features
• Autonomous Extraction of Real Time Model and State
• Self Regulating
• Self Managing (Operations Planning)
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Flexible AC-OPF: Look-Ahead PlanningFlexible AC-OPF: Multi-Time Step Optimization
• Multi-step AC-OPF problem with discretized device dynamics (five to ten minutes) – object oriented approach
• Stack of coupled AC-OPF problems (one per time step)
• Non-convex problem
• Accurate modeling of nonlinearities and full active-reactive dispatch
• Look-Ahead Horizon of 24 Hours
• Dispatch Horizon of one to two hours
05 April 2017 18
Charging During Solar Peak
PHEVCharge/ Discharge Schedule
Pre-Coolingphase
Turn-off phase
Thermostatic LoadTemperature of Cooled Space
Thermostatic LoadAverage Consumption Per Period
Pre-Coolingphase
Turn-off phase
The F-OPF guarantees non-intrusive load scheduling & considers network effects
Flexible AC-OPF: Sample Results
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Summary Evolving Electric Grid
Active Distribution Network
DER Integration Challenges
Asynchronous Microgrid Interconnection
Microgrid Benefit for DER Integration
Centralized Protection & Control (CPC)
Microgrid Management System Using CPC Estimation Based Protection & Centralized Grid Protection
05 April 2017 20
An Invitation…
May 1-2, 2017
Georgia Tech Fault and Disturbance Analysis
Conference
May 3-5, 2017
Georgia Tech Protective Relaying Conference
See you in Atlanta in May…
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Further Reading R. Das, V. Madani and A.P. (Sakis) Meliopoulos, “Leveraging Smart Grid Technology
and Using Microgrid as a Vehicle for DER Integration”, Accepted for presentation at the Eighth Conference on Innovative Smart Grid Technologies (ISGT), Washington DC, USA, April 23-26, 2017, Paper 0037.
M. Bollen, R. Das, S. Djokic, P. Ciufo, J. Meyer, S. Rönnberg and F. Zavoda, “Power Quality Concerns in Implementing Smart Distribution-Grid Applications”, in Proc. IEEE Trans. Smart Grid, Vol. 8, Issue 1, pp. 391-399, January 2017.
Working Group on Centralized Substation Protection and Control, IEEE Power System Relaying Committee, “Advancements in Centralized Protection and Control within a Substation”, in Proc. IEEE Trans. Power Delivery, Vol. 31, No. 4, pp. 1945-1952, August 2016.
R. Das, V. Madani, F. Aminifar, J. McDonald, S. S. Venkata, D. Novosel, A. Bose and M. Shahidehpour, “Distribution Automation Strategies: Evolution of Technologies and the Business Case”, in Proc. IEEE Trans. Smart Grid, pp. 2166-2175, July 2015.
V. Madani, R. Das, F. Aminifar, J. McDonald, S. S. Venkata, D. Novosel, A. Bose and M. Shahidehpour, “Distribution Automation Strategies Challenges and Opportunities in a Changing Landscape”, in Proc. IEEE Trans. Smart Grid, pp. 2157-2165, July 2015.