INIGRID - SMART BREAKER: AN INNOVATIVE COMPONENT FOR FUTURELOW VOLTAGE POWER DISTRIBUTION

AIMS OF INIGRID

1. Develop innovative sensors and actuators for the

customer and distribution grid domain

2. Integrate these into future-proof automation architecture

and protocols

3. Perform cost benefit analysis for selected grid integration

approaches with and without iniGrid technology

4. Ensure flagship character by interlinked field trials in

customer and grid operation domain

USE CASES:

Use case a: Energy management at prosumer level / electric mobility

Use case b: Low voltage network optimization

Use case c: Medium voltage network optimization at substation level

Use case d: Medium voltage network optimization at management system level

Use case e: Distribution optimization across voltage levels

TECHNOLOGY BENEFITS:

• Very fast current switch off

• “Arc free” switching

• High number of switching cycles

• Remote control

• AC/DC capability

BENEFITS FOR CUSTOMERS:

• Remote control

• Communication enabled

• Metering capabilities

• Enhanced protection

• Smart Grid, AC/DC Microgrid,…

HYBRID CIRCUIT BREAKER

Comprises of an electromechanical contact(bypass relay, BPR) and a semiconductorswitch (SS) element in parallel. A serialdisconnector (galvanic separation relay,GSR) provides the required galvanicseparation between line and load side.

ADVANTAGES:

• Fast interruption and protection

• Added intelligence, features (IoT)

CHALLENGES:

• Requires dedicated power electronicswitching module

• Needs ultra-fast mechanical switchingmechanism

• Fast fault current detection (<100µs)

REQUIREMENTS:

• Fast short circuit

detection, to limit

current through

semiconductor

(junction temperature

is the limiting factor)

• Reliable detection of

“non–short circuit

events” ( e.g.: motor

start-up current,

transformer-inrush

current, capacitive

inrush current, abrupt

load changes, …)

WOLFGANG HAUER // wolfganghauer@eaton.com // MICHAEL BARTONEK // michaelbartonek@eaton.com // MARK STEFAN // mark.stefan@ait.ac.at

1, 2 Eaton Industries (Austria) GmbH, Vienna.

3 AIT Austrian Institute of Technology GmbH, Center for Energy, Vienna.

Under-/

Overvoltage

Release Contactor

Reclose

Unit

Auxiliary

ContactSmart Meter

SmartBreaker

Circuit Breaker

+

Residual Current

Device (RCD)

Integrate into ONE product

THE ALGORITHM:

• For switching criteria, the

current ( 𝑖 ) and its time

integral ( 𝑖 𝑑𝑡) are used.

• Maximum integration time

may be over one period of 50

Hz

• A locus curve that encloses

all circular diagrams possible

in a normal operation is

derived.

• Short circuit is detected for

values that are outside of the

locus curve.

normal operationshort circuit detected

𝑖 − 𝑦02

𝑎2+𝑖 − 𝑥0

2

𝑏2≤ 1

𝑖∙𝜔𝐼 𝑛

Load current flows across BPR and GSR

BPR opens and SS takes over short circuit current

GSR opens

Normal operation:

Short circuit:

Fault isolation:

Short circuit interruption:

Sho

rt c

ircu

itcu

rre

nt

inte

rru

pti

on

SS is switched off

Bypass

relay

(BPR)

Galvanic

separation

relay

(GSR)

Semiconductor

switch

SS

BPR GSR

Main control block

HMI & RF-Interface

Hybrid

Switch

Hybrid

Switch

RCD

Unit

SHORT CIRCUIT BREAKING CAPABILITY:OVERLOAD AND SHORT CIRCUIT DETECTION A comparison of breaking capabilities of

molded case circuit breaker (MCCB),

miniature circuit breaker (MCB), and

SmartBreaker clearly demonstrates high

current limiting capability and short

interruption time (tint), of SmartBreaker

(see Table 1 and Figure 3).

The let-through energy (I2t) of

SmartBreaker (green line, Figure 3) is

only 5% of I2t of MCB (blue line) and

0,2% of MCCB (red line). This means

less stress to fault loads and supply

lines. The black line represents the

prospective short circuit current of 10 kA

to which all breaker types were subjected

to.

This is achieved by fast fault detection,

and high short circuit turn–off capability

of semiconductor switch.

SMART BREAKER DEMONSTRATOR:

Breaker Type I2t (kA2s) tint (ms)

MCCB 276,7 8,95

MCB 10,4 5,06

SmartBreaker 0,5 0,64

Table 1: Interruption times and let-through energies of different

circuit breaker types.

Fig. 3. Oscillogram of interruption current during successful

10 kA short circuit interruption of MCCB, MCB and SmartBreaker.

Fig. 4. 1st Prototype of SmartBreaker with nominal current of

𝐼𝑛 = 45 𝐴 and short circuit current breaking capacity of 𝐼𝑠𝑐 = 10 𝑘𝐴.

Fig. 2. 2D locus curve criterion of overload and short circuit detection algorithm.

Fig. 1. SmartBreaker concept including monitoring, remote control,

and protection functionality all in one device.

Fig. 1. Turn off sequence of SmartBreaker during short circuit fault

This work is based on findings of the

project iniGrid, commissioned as

flagship project by Österreichische

Forschungsförderungs-gesellschaft

mbH (FFG) as part of e!MISSION.at 4th

call for proposals.