analysis of protection malfunctioning in meshed distribution grids
DESCRIPTION
Analysis of Protection Malfunctioning in Meshed Distribution Grids. Evita PARABIRSING Dr. Edward COSTER Dr. Marjan POPOV Stedin- The Netherlands Stedin – The Netherlands TU Delft – The Netherlands - PowerPoint PPT PresentationTRANSCRIPT
Frankfurt (Germany), 6-9 June 2011
Analysis of Protection Malfunctioning in Meshed Distribution Grids
Evita PARABIRSING Dr. Edward COSTER Dr. Marjan POPOVStedin- The Netherlands Stedin – The Netherlands TU Delft – The [email protected] [email protected] [email protected]
Paper 0374
Frankfurt (Germany), 6-9 June 2011
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
Presentation Overview
Frankfurt (Germany), 6-9 June 2011
Introduction Problem definition:
Short Circuit
If = If_1 + If_2
If
If_1
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% 100%
Short Circuit
k
If
kZ1 (1-k)Z1
Cable length = 1.97
km
Frankfurt (Germany), 6-9 June 2011
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2x 10
4
Fault Location (0%<k<100%)
Thre
e p
hase s
hort
circuit c
urr
ent,
If
IfIf2b
(If - If2b)
0% 100%
18 kA
3,2 kA
14,5 kA
30%
If – If_2b If_2b
I> 840 A
“Dead Zone”
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
Three Phase Faults0% < k < 8% ~ 160 m of 1,97 km
Double Phase Faults0% < 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
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
V Z net
Load
IOC
IOC
IOC
DIR
DIR
DIR
Z1
Z2
Z3
Z4
Z5
I>> 14 kAt>> 0.3 secIe>> 1.2 kAte>> 0.3 secI> 840At> 2 secIe 120Ate 2 sec
I> 840At> 0.5 secIe 120Ate 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 Dr. Edward COSTER Dr. Marjan POPOVStedin- The Netherlands Stedin – The Netherlands TU Delft – The [email protected] [email protected] [email protected]