PSIM is a powerful simulation tool for power electronics, known for its fast performance. However, when simulating systems with lots of power converters, the overall simulation time can become significantly long. To address this, we are exploring methods to simulate multiple converters more efficiently, including AI reduced order modeling techniques, without compromising the accuracy of the results.
Active & Reactive power control
The application we 're working on involves active and reactive power regulation to a RL load using two T-type converters, as indicated in the schematic below.
A small mismatch in converter voltages leads to unequal active power sharing, while a mismatch in voltage output frequency results in unequal reactive power sharing at the load. As shown in the following figures, when the voltage control targets of the two inverters are identical, both converters supply the same active power.
However, when there is a slight difference between the voltage targets, the active power delivered by each converter to the load becomes unequal.
System modeling using romAI
romAI is a plug-and-play tool that enables the development of a neural network capable of predicting a system’s output based on training data.
The trained romAI model can then be deployed in Twin Activate, an 1-D simulation tool that allows the simulation of an entire system.
On our way to achieve less simulation time, we will use romAI models that will replace the T-type inverters, and they will be able to predict the output voltage without solving switching simulations on the background. If you have not experimented with romAI training before, you can read the following articles first.
For improving simulation speed, we created a Twin Activate model that can replace the above PSIM schematic. In the attached Twin Activate model:
- The 'romAI inverter' Superblocks include one T-type romAI inverter each.
- The 'Load' Superblock includes the electric load supplied by the romAI inverters
Using the attached setup we are able to compare romAI outputs with the PSIM ones, and this could be a kind of results validation
The active power is shown at the diagram below, and we can see how accurate the romAI models are, compared to the PSIM one.
Observing the above power plot, we see that the active power the converters supply to the load differ and start becoming equal at t = 1 sec. This is why at first the converters' voltage target is slightly different and become equal at t=1 sec.
The PSIM calculation produces the switching waveform, whereas the romAI result is smoother. In this case, we accept omitting switching ripple while still providing realistic transients, in exchange for much faster simulation performance. Furthermore the romAI models will not have unlimited bandwidth and it has the ability to act as a more realistic plant model than the average inverter but solving much faster than the switching one.
The romAI simulation is approximately three times shorter than the PSIM one, and this is going to be enhanced as the romAI deployment in PSIM is under development and will be available in PSIM next versions as a DLL.
In conclusion, romAI can lead to great results that are closely enough to PSIM ones in much less simulation time.
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