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 // [email protected] // MICHAEL BARTONEK // [email protected] // MARK STEFAN // [email protected]
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.