Understand dynamic and GFM mode

[NILOY BARUA]

Hello,

I have the below attached circuit. I am having below issues. Would appreciate if anyone could share some thoughts on the below points.

1. While running the circuit in static mode, the loads are not consuming their maximum load. Is it normal or each load should draw loads as per their mention rating?
2. While running in a dynamic mode, if I open and reclose the DG breaker (F1G) there is a swing in the system after reclosing. This impacts all over the system and never stabilizes. I have read some posts here and put H=3 and D=0 or 1. Stil,l it is not working. How can we stabilize the system, is it possible or adding a DG will always have this swing?
3. Now, lets consider GFM mode. If we close 108 breaker (which is open in the diagram) and put battery there(BUS204) .
   My questions are - 1. Can we run the circuit for ms time range or whole day?
   2. Wy cant we start dynamic mode before islanding mode?
   3. Why and what does this line stand for "edit Storage.Battery ControlMode=GFM SafeVoltage=0"? And why we need to write it after opening breaker? I tried to place it before breaker opening but it is not working.
   4. Can we put PV as well under Bus105? Hence, can we have PV and battery both as GFM mode and both act as GFM?

For GFM mode my queries are based on the below instruction.
! Creating Island mood by opening SW102
open Line.SW102 terminal=1
solve

Solve mode=dynamic number=200 stepsize=0.0001
set loadshapeclass=daily
solve

edit Storage.Battery ControlMode=GFM SafeVoltage=0 State=Discharging

close Line.SW102 terminal=1
solve

Note- Question 1 and 2 are based on original circuit which attached.

[Davis Montenegro]

Hello,

Regarding your questions:

1. While running the circuit in static mode, the loads are not consuming their maximum load. Is it normal or each load should draw loads as per their mention rating?

Of course, that's why it is called snapshot, in this simulation mode it does not follow any load shape or reference (unless specified through commands like "set LoadShapeClass").

2. While running in a dynamic mode, if I open and reclose the DG breaker (F1G) there is a swing in the system after reclosing. This impacts all over the system and never stabilizes. I have read some posts here and put H=3 and D=0 or 1. Stil,l it is not working. How can we stabilize the system, is it possible or adding a DG will always have this swing?

When having sustained oscillations on a system it is time to consider damping. Damping can be provided normally by the circuit and its a natural feature, this is, it can be controlled using linear elements in most cases. You can try to add damping using the machine as you have been trying so far, but I don't think it will work, probably your machine is too small. Instead, try with a passive element. Remember the analogy of the RC circuit for charging and discharging...

3. Now, lets consider GFM mode. If we close 108 breaker (which is open in the diagram) and put battery there(BUS204) .
My questions are 
- Can we run the circuit for ms time range or whole day?

Both. But for dynamics you need a small integration step (ms). YOu can simulate a whole day using ms, but it will take time.

-. Wy cant we start dynamic mode before islanding mode?

Yes you can, who said you cannot?

-. Why and what does this line stand for "edit Storage.Battery ControlMode=GFM SafeVoltage=0"? And why we need to write it after opening breaker? I tried to place it before breaker opening but it is not working.

Of course, if you understood the GFM concept correctly, you'll notice that GFM mode cannot work when connected to the grid since GFM does not have PLL and serves as reference. Even though there is some literature talking about multiple GFM in the same system, the model in OpenDSS is recommended for only 1 GFM per island/system. Otherwise, you'll have to guarantee a phase angle of 0 at the terminals of the GFM device to prevent a short circuit. However, you can start with the model connected in GFL and then when the island is formed change to GFM.

-Can we put PV as well under Bus105? Hence, can we have PV and battery both as GFM mode and both act as GFM?

Same as above.

Best regards,

[NILOY BARUA]

Hello Davis,

Thank you for clarifying all the points. Would appreciate if you could share your thoughts on the below points.

1. In case of dynamic, as the DG swing is not stabilizing even if after considering Damper value. If we use MVA size generator than it stabilizes. But practically for load like this considering MVA size generator is not sensible. However, if we use dynamic equation and generator model=7 the system stabilizes. Do you have any thoughts on that!
2. I have considered battery in BUS=204 and PV in place of generator (from the attached circuit). Here, Battery is initially charging and in GFM mode and PV is in GFL mode (by default). I have written the below code and attached are the outcome.
   My queries are-
   a) The Battery was initially in charging condition but here its zero and after breaker reclosing the breaker starts supplying. Which is not following GFM mode.
   b) The PV initially provides power and after Breaker closing it never supply. Unable to understand why.

Code -
// Define daily load shape
New LoadShape.MyLoadShape npts=24 interval=1 mult=(1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0)

// Define a simple load shape for the PV system
New Loadshape.PVShape npts=24 interval=1 mult=(1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1)

// Link the load shape to the PV system
Edit PVSystem.SolarPV daily=PVShape

// Define Battery
New "Storage.Battery" phases=3 conn=delta bus1=204 kV=13.8 kva=500 kWrated=500 kWhrated=2000 %stored=50 %reserve=20 // 204 BUS
~ %EffCharge=80 %EffDischarge=80 %IdlingkW=1 %R=50 %X=50 State=Charging kP=0.3 KVDC=0.700 PITol=0.1

// Define Solar panel
New "PVSystem.SolarPV" phases=3 conn=delta bus1=LDG kV=13.8 kva=500 pmpp=500 daily=pvshape %R=50 %X=50 kP=0.1 KVDC=0.700 PITol=0.1

! Grid forming inverter mode requires an InvControl for monitoring the current
New InvControl.StoCtrl DERList=[Storage.Battery] mode=GFM !eventlog=yes

New Monitor.Feederpower element=Line.Line1 terminal=1 mode=1 ppolar=no
New Monitor.SolarPQ Element=PVSystem.SolarPV Terminal=1 Mode=1 ppolar=no
New Monitor.BATTPQ Element=Storage.Battery Terminal=1 Mode=1 ppolar=no
New Monitor.101PQ Element=Line.Line5 Terminal=1 Mode=1 ppolar=no
New Monitor.105PQ Element=Line.Line6 Terminal=1 Mode=1 ppolar=no

set voltagebases = [13.8 4.16 .48 0.208]
calcvoltagebases

BusCoords CSVFile="E:\Course details\Spring 2024\OpenDSS\Banshee One feeder\BusCoords Banshee_BusXY.csv"

Solve
!Dynamic mode
Solve mode=dynamic number=200 stepsize=0.001
! Creating Islanding mode by opening SWFeeder (main breaker)
open Line.SWFeeder terminal=1
solve number=1000

edit Storage.Battery State=Discharging ControlMode=GFM SafeVoltage=0

close Line.SWFeeder terminal=1
solve number=5000