INIGRID - SMART BREAKER: AN INNOVATIVE COMPONENT FOR FUTURE LOW 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 semiconductor switch (SS) element in parallel. A serial disconnector (galvanic separation relay, GSR) provides the required galvanic separation between line and load side. ADVANTAGES: • Fast interruption and protection • Added intelligence, features (IoT) CHALLENGES: • Requires dedicated power electronic switching module • Needs ultra-fast mechanical switching mechanism • 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 Contact Smart Meter SmartBreaker Circuit Breaker + Residual Current Device (RCD) Integrate into ONE product THE ALGORITHM: • For switching criteria, the current ( ) and its time integral ( ) 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 operation short circuit detected − 0 2 2 + − 0 2 2 ≤1 ∙ 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: Short circuit current interruption 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 (t int ), of SmartBreaker (see Table 1 and Figure 3). The let-through energy (I 2 t) of SmartBreaker (green line, Figure 3) is only 5% of I 2 t 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 I 2 t (kA2s) t int (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. 1 st Prototype of SmartBreaker with nominal current of = 45 and short circuit current breaking capacity of = 10 . 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.