Frankfurt (Germany), 6-9 June 2011 Analysis of

Frankfurt (Germany), 6-9 June 2011 Analysis of Protection Malfunctioning in Meshed Distribution Grids Evita PARABIRSING Stedin- The Netherlands [email protected] Dr. Edward COSTER Stedin – The Netherlands [email protected] Paper 0374 Dr. Marjan POPOV TU Delft – The Netherlands [email protected]

Frankfurt (Germany), 6-9 June 2011 Presentation Overview Introduction Analysis of Short Circuits and Protection Relay Detection in a 25.6 kV Meshed Grid Section Possible Solution Strategy Conclusions Evita N. Parabirsing – The Netherlands – RIF Session 3 – Paper 0374

Frankfurt (Germany), 6-9 June 2011 Introduction Problem definition: Short Circuit If 1 If If 1 If 2 If If 2 Directional Relay (DIR) mal-operation occurs in networks with similar construction

Frankfurt (Germany), 6-9 June 2011 Analysis of Short Circuits and Protection Relay Detection in a 25.6 kV Meshed Grid Section 25.6 kV Meshed grid section IOC overcurrent relay DIR directional relay

Frankfurt (Germany), 6-9 June 2011 Analysis of short circuits and circulating fault currents If Short Circuit 0% 100% kZ1 (1-k)Z1 k Cable length 1.97 km

Frankfurt (Germany), 6-9 June 2011 0% 100% 30% If 2b If – If 2b f T hree phas e s hort c irc uit c u rrent,I 4 I 840 A “Dead 2 x 10 18 kA 1.8 1.6 14,5 kA 1.4 1.2 1 0.8 0.6 0.4 If If2b 3,2 kA 0.2 0 (If - If2b) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Fault Location (0% k 100%) 0.8 0.9 1

Frankfurt (Germany), 6-9 June 2011 For all types of short circuits there are certain ‘dead zones’ available in the network, caused by low fault currents which are detected by the directional relay (DIR) System Fault Dead Zone Cable Length 0% k 8% 160 m of 1,97 km 0% k 9% 180 m of 1,97 km Single Phase to Ground Faults 0% k 15% 300 m of 1,97 km Double Phase to Ground Faults 0% k 8% 160 m of 1,97 km Three Phase Faults Double Phase Faults

Frankfurt (Germany), 6-9 June 2011 Overview of ‘dead zones’ in the studied network

Frankfurt (Germany), 6-9 June 2011 Possible solution strategy Is there a possibility that faults within the ‘dead zone’ could be detected by the I , Ie settings of the IOC relays ? Step 1: Detected fault currents for faults within ‘dead zone’ System Fault Within Dead Zone If(IOC) Three Phase Faults 0% k 10% 15.6 kA If(IOC) 16 kA

Frankfurt (Germany), 6-9 June 2011 Step 2: Detected fault currents for faults outside the protected area System Fault Outside Dead Zone If(IOC) Three Phase Faults 0% k 10% 11.4 kA

Frankfurt (Germany), 6-9 June 2011 Proposed I , Ie and t , te settings of the IOC relays: System Fault Inside Dead Zone Outside Dead Zone Three Phase Faults 15.6 kA If(IOC) 16 kA If(IOC) 11.4 kA I Ie t , te 11.4 kA ( I ) 15.6 kA 0.99 kA (Ie ) 1.36 kA 0.3 seconds IOC V Z net DIR Z2 IOC I 14 kA t 0.3 sec Ie 1.2 kA te 0.3 sec I 840A t 2 sec Ie 120A te 2 sec Z1 Z3 DIR Z4 IOC Load DIR Z5 I 840A t 0.5 sec Ie 120A te 0.5 sec

Frankfurt (Germany), 6-9 June 2011 conclusions Analysis and Simulation results show that there exist ‘dead zones’ within the protected zones of the studied network ‘Dead zones’ will always be available in network sections with single point of supply. The ‘dead zones’ are caused by the low magnitude of the fault current through the Directional relay By activating and adjusting the I , Ie and t , te settings of the overcurrent protection relays in this study case, selective switching can be achieved for short circuits within ‘dead zones’

Frankfurt (Germany), 6-9 June 2011 Thank You Paper 0374: Analysis of Protection Malfunctioning in Meshed Distribution Grids Evita PARABIRSING Stedin- The Netherlands [email protected] Dr. Edward COSTER Stedin – The Netherlands [email protected] Dr. Marjan POPOV TU Delft – The Netherlands [email protected]