One of the most exciting features of the current RTDS generation of real-time simulation hardware – NovaCor 2.0 – is the new large non-real-time (LNRT) simulation capability. LNRT allows users to study much larger networks than would normally be possible by switching from real-time to non-real-time simulation mode. NovaCor 2.0 hardware and software version RSCAD FX 2.2 or above are required for LNRT simulation.

Non-real-time simulation, in which the execution time differs from the simulation timestep and the simulation runs slower – or less commonly, faster – than real-time, has always been possible with the RTDS Simulator. In the past, the allowed network size did not change when switching to non-real-time mode (i.e. power system node and load unit limits remained the same). The novel aspect of the new LNRT feature is the fact that the maximum network size increases drastically when in non-real-time mode. In LNRT mode, the simulated circuit can be approximately 10 times larger than it can be in real-time mode:

• LNRT accommodates 360 single-phase nodes per licensed core of the NovaCor 2.0 platform.
• Each licensed core can also contain components totalling up to 3,600 load units.

This means that a fully-licensed NovaCor 2.0 chassis (with 10 licensed cores) is capable of simulating up to 1,200 three-phase buses in full electromagnetic transient (EMT) detail using LNRT mode. This feature offers unprecedented access to the simulation of larger-scale networks with the RTDS Simulator without sacrificing the detail needed to de-risk the integration of inverter-based resources and study their control.

Typical performance in LNRT mode is 4-5 times slower than real time. Regardless of computational load, the minimum execution time per timestep in LNRT mode is 200 µs – for a simulation timestep of 40 us, that’s 5 times slower than real time. Customers using standard offline EMT simulation tools for power system studies can expect a given case to run at least 20 times faster using LNRT. These efficiency gains can make a big difference for institutions running large, complex cases and/or doing iterative testing.

Substep subnetworks for power electronics simulation can be included in LNRT mode. To optimize processing resources, manual allocation mode can be used to assign several Substep hierarchy boxes to a single core in LNRT mode. GTSOC V2 black box control models are also supported; black-boxed vendor controls for inverter-based resources and other assets can be integrated into the large-scale non-real-time simulation. LNRT mode does not support I/O.

For more details on LNRT, set the Hierarchy Box component in RSCAD FX 2.2 or above to LNRT mode, and then check the Help file in the component for documentation.