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

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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

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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.