This circuit shows how to use the SSN Iterative MOV algorithm to simulate a series compensated transmission systems (single-phase).

The case is a single-phase one consisting of a 15 GVA source connected to a 200 km line and a load of 2GW with a reactor of 330MVA. The line is compensated in the middle by a series capacitor set at 40% of the total line reactance. Both the capacitor and load reactor are protected by MOVs.

In the test, a fault is made at the load. Shortly after, the 2GW load is disconnected. The fault initially creates large voltage swings on the series capacitor which are mitigated by MOV1 in the diagram. When the load is dropped, resonance occurs between the capacitor and the load inductance. Load overvoltages are mitigated by MOV2.

From a simulation point of view, it is well-known that MOV1 will be quite stable because it is connected across a large capacitor. MOV 2, however, is more prone to numerical instability and inaccuracies.

Hypersim at 50 µs, also an iteration capable real-time simulator, cannot achieve the accuracy of SSN with art5 solver at the same time step. The later response really matches well with the 1 µs reference simulation. The SSN art5 solver is an order 5 L-stable matrix exponential approximant unique to ARTEMiS-SSN.

**Note:** this model was used for the following paper: C. Dufour, O. Tremblay, "Iterative Algorithms of Surge Arrester for Real-Time Simulators", 18th Power Systems Computation Conference (PSCC'14), Wroclaw, Poland, August 18-22, 2014.