Transcript
PTCC Automation OverviewFor Automatic Circuit Reclosers and Load Break Switches
Automation Features
Automatic Protection Group Selection
Generator Control
Automatic Change-over
Loop Automation
Automatic Protection Group Selection
Automatic Protection Group Selection (APGS) allows the appropriate Protection Group to be selected automatically without the need for operator intervention.
It works by automatically changing between Protection Groups depending on the direction of power flow.
Source Load
Forward Power Flow
Protection Group A
Reverse Power Flow
Protection Group B
Where is APGS used?
Sometimes a circuit breaker is used at a location in a supply network where the power flow can be in either direction depending on the configuration of the rest of the network.
One example of this is a network tie point where the operator may have to select a different group of protection settings to compensate for a change in power flow when changing the network configuration.
Emergency switching configurations may require more than one pair of Protection Groups.
Fdr 1
Fdr 2
The Selection Rules
Each pair of Protection Groups (A&B) (C&D) (E&F) (G&H) (I&J), contains one Primary and one Alternate Protection Group.
The number of APGS pairs depends on how many Protection Groups have been configured.
When the power flow is in the positive direction (source to load) Primary Protection Group A,C,E,G or I is used.
When the power flow is negative, Alternate Protection Group B,D,F,H or J is used.
For APGS to generate a change from Primary to Alternate Protection Group, the power flow must be >50kW in the negative direction for longer than the set period.
To Revert to Primary Protection group the power must be >50kW in the positive direction for longer than the set period.
Protection Groups
A B C D E F G H I J
Pri Alt
A B
C D
E F
G H
I J
Generator Control
Generator Control Operation
The Generator Control option can disconnect the normal source of supply when it fails and automatically start a standby generator to supply the load.
When the normal source of supply is restored, the generator is automatically shut down and the supply reconnected.
Generator start-up
Generator
IOEX
ACR
Source & Load side
LIVE
Source & Load side
DEAD
Switch
OPEN
Generator
START Request on
Generator
RUNNING
CB
Generator
IOEX
ACR
Power restoration
Generator
RUNNING
Source & Load side
LIVE
Generator
START Request off
Generator
OFF
Switch
CLOSED
CB
Summary of Operation
Starts generator Senses loss of source side supply. Isolates normal supply line. Operates generator via IOEX output. Keeps generator running till power supply
is restored.
Reverts to normal supply Senses restoration of normal supply. Turns generator off. Reconnect to normal supply.
Safety Closing of switch is disabled when
generator supply is active.
Generator Control settings
HV Dead Time Amount of time source side bushings are
“dead” before any action performed by Generator Control.
Also used to detect when the generator has stopped.
Range: 1 to 600 sec
HV Live Time Amount of time source side bushings are “live”
before any action performed by Generator Control.
Also used to detect when a generator is running.
Range: 1 to 600 sec
Control State: What Generator Control is doing.
Configuration in WSOS
Automatic Change-Over
Automatic Change-Over
The Automatic-Changeover (ACO) scheme enables supply from either of two sources in support of a single load.
This scheme is normally used in support of a critical load such as a hospital to ensure that alternate supply is always available in the
event of power failure.
Automatic Change-over Operation
Preferred Alternative
Automatic Restoration
Supply may be automatically restored using either of the following principles depending on the compatibility of the supply at each feeder.
Break Before Make In this mode the Master device will instruct
the Slave device to open and then wait until the Master switch’s load side bushings are confirmed as dead before closing itself and connecting to the load. This will cause a short interruption of supply to the load during the confirmation period.
Make Before Break In this mode the Master will close onto an
energised load and then instruct the Slave to open after confirming the presence of HV for a specified period, without interruption of supply to the load.
Make Before Break Restoration
Preferred Alternative
Break Before Make Restoration
Preferred Alternative
Automatic Change-over Communications
Preferred Alternative
Control Centre
DNP3
ACO
Auto-Changeover – Important Points
Auto-Changeover cannot be made available if other automation features are available.
Auto-Changeover can only be used when DNP3 or another suitable protocol is available.
Make Before Break can only be used for restoration when the preferred and alternative supply are compatible.
When the Auto-Changeover scheme is installed the SLAVE device must be installed, configured and checked first before the MASTER device is configured.
Loop Automation
Loop Automation – An Overview
Loop Automation is a Distributed System Automation (DSA) scheme that will restore supply to fault free sections of a network if they have been disconnected because of a fault in another section of the network.
Loop Automation can also restore the normal network configuration automatically when the faulted section is repaired.
The distributed intelligence embedded in the reclosers operates the scheme without communications or operator intervention by using the built-in voltage detection of Nu-Lec reclosers.
No additional equipment is required.
Loop Automation Operating Principal
Loop Automation reconfigures a network to restore supply to fault free sections of a network.
It achieves this through a number of steps:
Isolate faulted section.
Reconfigure network so that unfaulted sections receive supply.
Automatically restore the normal configuration when the fault is removed.
Types of Recloser
Loop Automation defines 3 “types” of reclosers. Feeder recloser
– Recloser closest to the substation. Tie recloser
– Normally Open point where two feeders meet.
Mid-point recloser
– Reclosers anywhere on network between Feeder and Tie reclosers.
TieRecloser
FeederReclosers
Mid-pointReclosers
Loop Automation re-configuration rules
Rule A: The Feeder Recloser trips when it loses
supply. Rule B:
Mid-point Reclosers changes to “B” Protection group and activates single shot mode when the source supply is lost.
Rule C: Tie Recloser closes when supply is lost on
one side only. i.e. Other supply is available.
FeederReclosers
Mid-pointReclosers
TieRecloser
Loop Automation re-configuration - Example
Rule B: Mid-point Reclosers changes to “B”
Protection group and activates single shot mode when the source supply is lost.
Rule C: Tie Recloser closes when supply is lost on
one side only. i.e. Other supply is available
FeederReclosers
Mid-pointReclosers
TieRecloser
A Prot GroupB Prot Group Single Shot
Loop Automation Restoration Rules
Rule D: The Feeder Recloser closes when source
supply is restored and it was tripped by LA, or When supply is restored on both sides.
Rule E: Mid-point Reclosers closes when supply is
restored to both sides. Rule F:
Tie Recloser trips when power flow reduces by 50%, or
Power flow direction reversal.
FeederReclosers
Mid-pointReclosers
TieRecloser
B Prot Group Single Shot
Loop Automation restoration – Mid-Point
Rule E: Mid-point Reclosers closes when
supply is restored to both sides.
FeederReclosers
Mid-pointReclosers
TieRecloser
B Prot Group Single Shot
Loop Automation restoration – Tie
Rule F: Tie Recloser trips when power flow
reduces by 50%, or Power flow direction reversal
FeederReclosers
Mid-pointReclosers
TieRecloser
A Prot GroupB Prot Group Single Shot
Supply Auto-Changeover
In addition to improving the quality of a supply in a network, Loop Automation can also be used to provide a secure supply to a critical load by implementing an Auto-Changeover (ACO) scheme.
Loop Automation as Supply Auto-Changeover
FeederRecloser
TieRecloser
Rule C:Tie Recloser closes when supply is lost on one side only. i.e. Other supply is available
Rule A:The Feeder Recloser trips when it loses supply.
Loop Automation as Supply Restoration
FeederRecloser
TieRecloser
Rule D:The Feeder Recloser closes when source supply is restored and it was tripped by LA, orWhen supply is restored on both sides
Rule F:Tie Recloser trips when power flow reduces by 50%, orPower flow direction reversal
Considerations when using Loop Automation in a Auto Change-over scheme
Advantage
No communications required between reclosers.
Disadvantage
Only Make before Break restoration is available.
Automation Overview
A couple of points to note if you are considering using automation features:
Loop Automation is a licensable feature and will only work with controllers which have their CAPM4/5 serial numbers embedded into the software.
Loop Automation, Auto Changeover and Generator Control are mutually exclusive features.
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