MMC : Mel System into Medium Voltage Distribution System ... · Contact: Janviere Umuhoza-...

𝑉𝐴𝐵,𝑚𝑎𝑥 = 0.612 𝑚 − 1 𝑉𝑑𝑐

Objectives

Progress

Approach Challenges

Future Plans

SiC-Based Direct Power Electronics Interface for Battery Energy Storage

System into Medium Voltage Distribution System (Project GR-17-03)

Janviere Umuhoza, Haider Ghazi Mhiesan , Kenneth Mordi, Chris Farnell, H. Alan MantoothNSF I/UCRC on GRid-connected Advanced Power Electronic Systems (GRAPES), University of Arkansas

The team is grateful for the financial support from the National Science

Foundation Industry/University Cooperative Research Center on

GRid-connected Advanced Power Electronic Systems (GRAPES).

Contact: Janviere Umuhoza- jumuhoza@uark.edu | H.Alan Mantooth - mantooth@uark.edu

Contact Information & Acknowledgments

• Using ≥ 10 kV SiC modules to build a power

electronics interface to integrate battery energy

storage into a medium voltage distribution system

• Transformerless interface, without the bulk step-up

60 Hz transformer

• Taking advantage of high break-down voltage of

SiC devices to minimize the number of modules

Medium Voltage

Distribution Line

DC/AC Three-Phase

Inverter

Step-up

60 Hz

Transformer

Medium Voltage

Distribution Line

DC/AC Three-Phase

MMC Inverter

Transformerless

MMC: Multililevel

Modular

Cascaded

• Multi-level Modular Cascaded H-bridge Inverter is used to realize a

transformerless power electronics interface

• The topology with H-bridge cells has a reverse blocking capability,

preventing AC-infeed into DC side short circuits

• Galvanic isolation and BIL requirement

• Active-power control of individual converter cells

• State of charge balancing

• Fault tolerance of the cascaded converter

• Control structure is highly centralized

• Complex system management

• Synchronization of PWM signals

Centralized Control Structure Decentralized Control Structure

• Proof of the concept Open loop simulation results

and testing results of the

topology

• Multi-carrier PWM

generation Phase-shifted PWM

• Active-power control

simulation Discharging the batteries

Charging the batteries

• Low-voltage prototype

• Signal conditioning board for closed loop controls

• On-going simulations in MatLab Simulink

• Galvanic isolation and BIL requirement

• AC filter design

• Design a fault tolerance scheme

• Implement the controls using CPLD/FPGA

• Build a high voltage prototype

Low voltage prototype A high voltage prototype

Topology with H-bridge cells

Open-loop testing results

Active power control

simulation results

1.2 kV, 50 A SiC

MOSFET module

SiC

Device

DC Bus

Voltage

# of

cells

AC 3Փoutput

1.2 kV 720 V 4 3. 525 kV

3.3 kV 1.98 kV 4 9.694 kV

10 kV 2.82 kV 4 13.8 kV

Hard switching, 40% safety

margin, amplitude modulation

ma = 1.

𝑉𝐴𝐵,𝑚𝑎𝑥 = 0.612 (𝑚 − 1) 𝑉𝑑𝑐Wℎ𝑒𝑟𝑒 𝑚 = 2𝑁 + 1, 𝑎𝑛𝑑𝑁 = # 𝑜𝑓 𝑐𝑒𝑙𝑙𝑠 𝑝𝑒𝑟 𝑝ℎ𝑎𝑠𝑒

Time (Sec)

Wat

tsV

olt

sA

mp

sV

olt

s

Vo

lts