Grid changes
Changes, like the change of a switching state or the change of an electrical parameter, occur every day. But not all changes are electrically relevant. Some values, like the name field, are purely descriptive; other fields, like the operational voltage of network feeders, are calculated automatically based on the power flow of the overlaying grid. Our change detection tries to identify relevant changes while ignoring changes that are so small that their electral implication can be considered irrelevant.
Implications
The implications of a grid being considered "changed" are various:
- In .Mon, it triggers a full re-simulation (if configured).
- In .Connect, it triggers the re-calculation of the hosting capacity.
- In .Sim, it triggers the grid-has-changed warning message.
- In short circuit, it triggers a recalculation (invalidation of cached result).
Threshold
We use the following threshold for fields representing electrical parameters. Any change below the threshold is ignored
| Grid Element | Property | Threshold |
|---|---|---|
| Bus | Voltage | 1 V |
| Bus | Self time | 1 ms |
| Connection | Resistance/reactance | 1 mΩ |
| Distance Protection | Final time | 1 ms |
| Distance Protection | Overcurrent | 1 A |
| Distance Protection | Min. grid impedance | 1 mΩ |
| Load/Generator | Power | 1 W/1var |
| Load/Generator | Annual consumption | 1 Wh |
| Load/Generator | Cos(phi) | 0.1 % |
| Line | Resistance/reactance | 1 mΩ/km |
| Line | Length | 1 cm |
| Line | Max. current | 1 mA |
| Line | Max. short circuit current | 1 A |
| Line | Capacitance | 1 nF/km |
| Network Feeder | Operational voltage | 0.1 % |
| Network Feeder | Operational angle | 0.01 rad |
| Network Feeder | Short circuit capacity a) | 1 kVA, 1 A, 1 mΩ |
| Network Feeder | X/R ratio | 1 % |
| Switch | Max. short circuit current | 1 A |
| Transformer | Rating | 1 kVA |
| Transformer | Short circuit voltage | 0.01 % |
| Transformer | Copper losses | 0.001 % |
| Transformer | Rated voltage at bus1/bus2 | 1 V |
| Transformer | Grounding resistance | 1 mΩ |
| Transformer | Grounding inductance | 1 mH |
| Tap changer b) | Setpoint | 0.1 % c) |
| Tap changer b) | Tap size | 0.1 % c) |
| Tap changer b) | Dead-band | 0.1 % c) |
| All elements | Name, Description, Year, … | Value ignored |
a) Value can be entered as power, current or impedance
b) Found in "Transformer" and "Voltage Regulator"
c) Relative to nominal voltage