Switched Shunt Model: FACRI_SS
AutoCorrection Properties
To be documented.
Model Equations and/or Block Diagrams
Parameters:
| uv1 | Switching Group 1 under voltage level 1 (pu) |
| uv2 | Switching Group 1 under voltage level 2 (pu) |
| uv1td | Switching Group 1 time delay level 1 (sec) |
| uv2td | Switching Group 1 time delay level 2 (sec) |
| inttd | Switching Group 1 first switch time delay, initial time delay (sec) |
| uv3 | Voltage at terminal bus that triggers Switching Group 2 switching logic (pu) |
| uv4 | Switching Group 2 under voltage low level (pu) |
| uv5 | Switching Group 2 under voltage high level (pu) |
| td1 | Switching Group 2 time delay for loop 1 (sec) |
| td2 | Switching Group 2 time delay for loop 2 (sec) |
| td3 | Switching Group 2 time delay for loop 3 (sec) |
| td4 | Switching Group 2 time delay for loop checks (sec) |
| td5 | Duration of time that conditions are checked Monitored Bus b while in each loop (sec) |
| Extra Object 1 | Capacitor 1 – Switching Group 1 |
| Extra Object 2 | Capacitor 2 – Switching Group 1 |
| Extra Object 3 | Reactor 1 – Switching Group 1 |
| Extra Object 4 | Reactor 2 – Switching Group 1 |
| Extra Object 5 | Reactor 3 – Switching Group 1 |
| Extra Object 6 | Capacitor a1 – Switching Group 1 |
| Extra Object 7 | Capacitor a2 – Switching Group 1 |
| Extra Object 8 | Reactor a1 – Switching Group 1 |
| Extra Object 9 | Monitored Bus b – Switching Group 2 |
| Extra Object 10 | Reactor b1 – Switching Group 2 |
| Extra Object 11 | Capacitor b1 – Switching Group 2 |
| Extra Object 12 | Capacitor b2 – Switching Group 2 |
The following pseudo code describes how the inputs are used to determine switched shunt operation:
Switching Group 1 Switching Logic
Each time that voltage and time delay conditions are met for Switching Group 1, the reactors and capacitors are checked in the following order until a device is found that can be switched. Reactors are tripped and capacitors are closed. Only one device is switched each time switching is required.
(1) Reactor 1
(2) Reactor a1
(3) Reactor 2
(4) Reactor 3
(5) Capacitor 1
(6) Capacitor a1
(7) Capacitor 2
(8) Capacitor a2
Switching Group 2 Switching Logic
Each time that voltage and time delay conditions are met for Switching Group 2, if the reactor is online it will be tripped first before any capacitor switching. Depending on voltage conditions, capacitors may or may not be turned on. When capacitors are switched, they are checked in the following order until a device is found that can be switched. Only one capacitor is switched each time switching is required.
(1) Capacitor b1
(2) Capacitor b2
If (Reactor online) Then Begin
Trip Reactor
If (VoltMeasBusb <= uv4) Then Begin
Do capacitor switching
End
End
Else If (not Reactor online) Then Begin
If (VoltMeasBusb <= uv4) or (VoltMeasBusb <= uv5) Then Begin
Do capacitor switching
End
End
Initialization at the start of transient stability run
FirstSwitchComplete = False
Initialize Switching Group 2 Loop Trackers
Operations performed at each time step
VoltMeas = Voltage at the terminal bus of the switched shunt to which this model is assigned
// If voltage falls below specified thresholds, timers are started to record how long the voltages remain below these thresholds.
// The specific timer pseudo code is not shown here.
If (not FirstSwitchComplete) and ( (VoltMeas < uv1 for inttd) or (VoltMeas < uv2 for inttd))
Then Begin
Check Group 1 Switching
FirstSwitchComplete = True
End
If (FirstSwitchComplete) Then Begin
If (VoltMeas < uv1 for uv1td)
Then Begin
Check Group 1 Switching
Reset Group 1 Timer
End
If (VoltMeas < uv2 for uv2td)
Then Begin
Check Group 1 Switching
Reset Group 1 Timer
End
End
If (VoltMeas > uv1) Then Begin
Reset Group 1 Timers
FirstSwitchComplete = False
End
// The condition of VoltMeas < uv3 triggers the checking of voltages at Monitored Bus b. This latches on for the duration specified by
// td4. The specific timer pseudo code is not shown here, but Group2Timer will be used to keep track of this.
VoltMeasBusb = Voltage at Monitored Bus b
If (VoltMeas < uv3) and (Group2Timer < td4) Then Begin
If (Group2Timer > td1) and (not Group2Loop1Done) Then Begin
Check Group 2 Switching
Group2Loop1Done = True
// Continue doing Check Group 2 Switching for td5 until some switching done
End
If (Group2Timer > td2) and (not Group2Loop2Done) Then Begin
Check Group 2 Switching
Group2Loop2Done = True
// Continue doing Check Group 2 Switching for td5 until some switching done
End
If (Group2Timer > td3) and (not Group2Loop3Done) Then Begin
Check Group 2 Switching
Group2Loop3Done = True
// Continue doing Check Group 2 Switching for td5 until some switching done
End
End
Else If (Group2Timer > td4) Then Begin
Reset Group 2 Timers
Reset Group 2 Loop Trackers
End