Transcript Analysis of Protection Malfunctioning in Meshed Distribution Grids
Frankfurt (Germany), 6-9 June 2011
Analysis of Protection Malfunctioning in Meshed Distribution Grids
Evita PARABIRSING Stedin- The Netherlands Dr. Edward COSTER Stedin – The Netherlands TU Delft – The Netherlands [email protected] [email protected]
Dr. Marjan POPOV [email protected]
Paper 0374
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
0% kZ1 If Short Circuit 100% (1-k)Z1 k Cable length = 1.97 km
Frankfurt (Germany), 6-9 June 2011
0% 100% 30% If – If_2b If_2b
2 x 10 4 1.8
1.6
1.4
1.2
1 0.8
0.6
0.4
0.2
I> 840 A “Dead Zone” 0 0 0.1
14,5 kA 18 kA 3,2 kA
0.2
0.3
0.4
0.5
0.6
Fault Location (0% 0.8 If If 2 b (If - If 2 b) 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 Three Phase Faults Double Phase Faults Single Phase to Ground Faults Double Phase to Ground Faults Dead Zone 0% < k < 8% 0% < k < 9% 0% < k < 15% 0% < k < 8% Cable Length ~ 160 m of 1,97 km ~180 m of 1,97 km ~300 m of 1,97 km ~ 160 m of 1,97 km Frankfurt (Germany), 6-9 June 2011 Overview of ‘dead zones’ in the studied network Frankfurt (Germany), 6-9 June 2011 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 Three Phase Faults Within Dead Zone 0% < k < 10% If (IOC) 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 Three Phase Faults Outside Dead Zone 0% < k < 10% If (IOC) 11.4 kA Frankfurt (Germany), 6-9 June 2011 Proposed I>>, Ie>> and t>>, te>> settings of the IOC relays: System Fault Three Phase Faults Inside Dead Zone 15.6 kA < If(IOC) < 16 kA Outside Dead Zone If(IOC)= 11.4 kA I>> 11.4 kA < ( I>> ) < 15.6 kA Ie>> 0.99 kA < (Ie>>) < 1.36 kA t>>, te>> 0.3 seconds Z1 IOC DIR V Z net Z2 Z3 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 IOC Z4 Z5 DIR DIR Load I> 840A t> 0.5 sec Ie 120A te 0.5 sec Frankfurt (Germany), 6-9 June 2011 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 Paper 0374: Analysis of Protection Malfunctioning in Meshed Distribution Grids Evita PARABIRSING Stedin- The Netherlands Dr. Edward COSTER Dr. Marjan POPOV Stedin – The Netherlands TU Delft – The Netherlands [email protected] [email protected]Possible solution strategy
conclusions
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