Smart Grid Research at The Ohio State University

Jin Wang, Mahesh Illindala wang.1248@osu.edu

November 28, 2016

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Renewable energy based charging facility

Vertically Integrated Research Topics

New switching devices

Circuits and control

System integration

Two Junction points

kk-1

(K)dcV

k+1=kS k+1S

kS k+1S

(K-1)dcV

Reference

Waveform

m1A

2A

21 AA kS

k+1S= k

k+1

Two Junction points

kk-1

(K)dcV

k+1

kS k+1S

(K-1)dcV

Reference

Waveform

m1A

2A

21 AA

300 kW Inverter for the Integration of Renewable Energy

Optimal PWM for Multilevel Inverters

SiC and GaN Devices

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Desired Features for Smart Grid Power Electronics

► Higher reliability

► Higher efficiency

► Lower cost

► Better stability in spite of constant

power loads

► More comprehensive system level fault detection and protection for microgrid

and dc networks

► Reduced complexity of High Voltage DC (HVDC) and Flexible AC Transmission

Devices (FACTs) with medium voltage SiC devices

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Research Project Examples and Research Platform

► SiC based Power Electronics for Utility Applications

► CERTS Microgrid

► Flexible Distributed Energy Resources

► Real-time simulation platform

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Example 1: SiC Devices for Utility High Voltage Applications

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The Need for High Voltage DC (HVDC) Systems

Source: Siemens, HVDC and Trans Bay Cable, 2005

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Evolution of Switching Devices

Dr. kamel Madjour, Silicon Carbide Market Updates, PCIM May 2014

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Trans Bay Cable Project

The world’s first IGBT based HVDC project (Yr. 2010).

Circuit topology: 200 kV DC, 600 MW, IGBT based Modular Multilevel Converter

(MMC)

In North America, four IGBT based HVDC projects have been approved or

commissioned.

Source: Siemens, HVDC and Trans Bay Cable, 2005

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Thyristor GTO, and IGBT based Solutions

Source: Siemens, HVDC Plus Basics and Principle

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The Rise of SiC Power Devices

Dr. kamel Madjour, Silicon Carbide Market Updates, PCIM May 2014

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SiC Based Medium Voltage MMC Project at OSU

►Team

• Longya Xu, Jin Wang, Fang Luo (OSU)

• Julia Zhang (Oregon State University)

• National Renewable Energy Laboratory (NREL)

• More than 10 students

►Idea

• White House Initiative to improve efficiency and reduce footprint of industrial MV drive systems

►Objective

• To build 1 MVA medium-voltage Modular Multilevel Converter and using SiCswitching devices

Compared to Si based solutions, SiC based solution will provide better

power quality and lower power loss.

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►Specifications

• Rated power of 1 MVA

• Up to 4160 V rms line-line

• Motor current up to 140 A rms

• Fundamental frequency up to 1000 Hz

►Results in the first two quarters

• Market survey of MV drives and SiC devices

• Characterization of two 1.7kV SiC devices

• Design and fabrication of gate drive board

• Design of main circuit components (capacitors, inductors)

• Design of DSP and FPGA controller boards

• Offline system simulations using MATLAB

Gate

Driver

Board

Load

Inductor

Coaxial Current

Shunt

Decoupling-

Capacitors

DC-link

Capacitor

Laminated

Bus Bar

DPT FixtureSiC Module

Vgs: 25 V/div

4 µs/div

Id: 100 A/div

Vds: 250 V/div

Hard switching waveform at 1160 V/300 A

Vds voltage overshoot is 100 VSingle Submodule Single MMC Arm

SiC Based Medium Voltage MMC Project at OSU

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Example 2: Modeling and Control of CERTS Microgrid

14Aerial View of the CERTS Microgrid

The first utility microgrid test bed with distributed energy sources and

storage devices.

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Vs

To gain a better understanding of the mechanical & electrical limiting conditions of distributed energy resources (DER)

Inverter-based DERs Synchronous

generator-based DERs

Any islanded microgrid can be subjected to its limiting conditions for overloads.

Project Objective

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Source: Datasheet of GM 8.1L engine, 8.1L, 8 cylinder – 496 cubic inches, General Motors

Mechanical torque limit, Tlim

Mechanical power limit, MPmax

Role of Fuel Map on the Mechanical Power Limit of DER

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Modeling Approach

Physics-based modeling of DERs without infringing

on confidential information of manufacturers

Modeling of essential characteristics to represent

the general behavior of DERs from a broad range of

manufacturers

Limiting conditions are not observed in scaled-down

laboratory microgrid experiments emulating engine

prime-mover by alternative means

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Synchronous Generator-based DER Model

Engine fuel map sets the

mechanical torque limit

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Mechanical power limit: Torque limit of the prime-mover Tlim

gets reflected as MPmax line on the P-f characteristics

Step load

0-80 kW

Mechanical Power Limit on the Synchronous Generator-based DER

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Mechanical torque limited at Tlim

Step load 0-80 kW

Impact of Limiting Conditions on the Synchronous Generator-based DER

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Inverter-based DER Model

Engine fuel map sets the

mechanical torque limit

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Mechanical power limit: Torque limit of the prime-mover Tlim

gets reflected as MPmax line.

Step load

0-94 kW

Impact of Limiting Conditions on the Inverter-based DER

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Step load

0-94 kW

Impact of Limiting Conditions on the Inverter-based DER

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Example 3: Flexible Distributed Energy and Storage Resources

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Energy Saving Formations in Nature

Drafting

“Formation flight of birds improves aerodynamic efficiency. Theoretically, 25 birds could have a range increase of about 70% as compared to a lone bird ..”

- Lissaman and Schollenberger, Science, 1970.

Leading

Flying Geese

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Energy Saving Formations in Nature

“Pelicans flying in a ‘V’ can glide for extended periods using the other birds’ air streams ..”

- Weimerskirch, et al., Nature, 2001.

Weimerskirch, et al., Nature, 2001.

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Flexible Distribution of EneRgy and Storage Resources (FDERS)

Adjust formation by adjusting virtual impedance of the

inverter based generation units.

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Flexible Distribution of EneRgy and Storage Resources (FDERS)

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Real-time Simulation based Hybrid Microgrid Testbed

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Why Real-time Simulation?

Why is real-time simulation important?

Provide hardware-in-the-loop functions

Hardware-in-the-loop methodologies:

Control Hardware-in-the-Loop (CHIL)

Validation of control strategies, e.g.electric machine drive speed / flux control

Power Hardware-in-the-Loop (PHIL)

Validation of both electrical equipment and associated control strategies

System-in-the-loop (SITL)

Validation of communication strategies, e.g. cyber security

http://ww.opalrt.com

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Main Grid

Transformer11

Fuse11 CB11

Converter Inverter

Local Energy

Storage (LES)

CB21 Fuse21

PVConverter Inverter

PV31CB31Fuse31

PVConverter Inverter

PV32CB32Fuse32

Converter Inverter

PHEV1

CB41

Fuse41

Converter Inverter

PHEV2

CB42

Fuse42

CB51

Fuse51

Load1(Normal)

CB52

Fuse52

Load2(Nonlinear)

CB61

Fuse61

Power

Amplifier

Real Time Simulator

Virtual Microgrid

LCL21

LCL41 LCL42

LCL32

LCL31

LCL61

208 V

Microgrid

Control Center

OPNET

Communication Server

SwitchboxVoltage, Current, Power,

Circuit breaker Status,

DSP control command

PHIL

SITL

SCADA

Overview of the OSU Hybrid Microgrid Testbed

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Features of the Testbed

Flexible and reconfigurable electric power network with real-time

simulation based Power Hardware-in-the-Loop (PHIL) unit

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Main Grid

ACDC

ACDC

ACDC

ACDC

ACDC

Transformer

Power

Amplifier

PHEV I

PHEV II PV Panel II

PV Panel I

AC Load LES

ACDC

PV Panel III

ACDC

PHEV III

PHIL based Virtual Branches

Real Hardware Branches

ACDC

ACDC

ACDC

ACDC

ACDC

Power

Amplifier

PHEV I

PHEV II PV Panel II

PV Panel I

AC Load LES

PHIL based Virtual Grid

Real Hardware Branches

ACDC

ACDC

ACDC

ACDC

ACDC

Power

Amplifier

PHEV I

PHEV II PV Panel II

PV Panel

I

AC Load LES

Real Hardware Branches

Microgrid 1

Microgrid 2

Utility

PHIL based Virtual Microgrids and the

main utility lines.

- Simulate one or several subsystems of the Mircogrid

- Simulate a scaled-down utility grid, and study the interaction between a Microgrid and the utility

grid

- Simulate one or more scaled-down Microgrids, and study the interaction between different

Microgrids

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Features of the Testbed (Cont’d)

Flexible and reconfigurable communication network with System-in-

the-Loop (SITL) unit

Low latency real-time Supervisory Control and Data Acquisition

(SCADA) system with high speed data acquisition

- Accept real network traffic

- Simulate different types of communication networks at real time

- Controllable latency, loss of packets, and cyber attack, etc.

- FPGA based Data Acquisition

- Real-time operation system dedicated for communication

Communication

Network

SimulatorReal Network

TrafficReal Network

Traffic

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Experiential Setup

Hybrid Microgrid Testbed setup

PHIL Inverter Pack FPGA based

SCADA

PHIL Real-time

Simulator

Real-time Monitoring

and Control Center

LES Unit

LANProgrammable

AC Load

The Monitoring and Control Station

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Experimental Results

The PHIL system and LES system are operating together in grid-

connected mode

The SCADA system is collecting information from the testbed and

displaying it in HMI

10 ms/div

Vgrid: 250 V/div

IPHIL: 2.5 A/div

ILES: 10 A/div

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Conclusions

► Future Smart Grids require innovation in both hardware and control

►Power electronic and especially SiC based power converters will bring new circuit functions and improved performance

►DER based Microgrid control need address interactions between of mechanical systems and electrical systems

►New control strategies can be implemented to improve system reliability

►New test platforms are needed

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To save a life, be a doctor.

To save the world, be a power

electronics engineer!

Thank you!

Questions?