RTDS News for Spring 2020

Exciting new models and features to check out in RSCAD®

Faulted transformer model

Our new faulted transformer model is based on a terminal duality equivalent. Common engineering challenges are addressed by replacing the popular star equivalent circuit with an equivalent based on terminal duality principles. 

The new model is a more realistic and practically accurate representation of a transformer’s magnetic circuit, including the representation of real physical leakages. It allows for a more accurate prediction of the magnetic inrush current, as well as full representation of the mutual coupling between branches, allowing for better model performance at the terminals. Under asymmetrical conditions, the model allows for the accurate evaluation of short circuit reactance by decomposing the leakage flux into axial and transverse components.

The new model is a game-changer in representing the transient behaviour of transformers and enabling the comprehensive closed-loop testing of transformer protection.

Small timestep to substep conversion tool

Our new Small Timestep to Substep conversion tool allows users to migrate cases that were developed in small timestep subnetworks to the new Substep environment. Substep has several advantages for power electronic simulation, including no hard limit on the quantity of resistive switches, the option to avoid fictitious losses at higher switching frequencies without decoupling VSCs from the rest of the network, and more nodes allowed per subnetwork.

Frequency scan component

Our new frequency scan component provides an analytical, offline impedance
scan of the simulated network. A new button in the Draft module allows the
user to invoke a frequency scan (DC – 1 MHz) prior to running the simulation.
This executes a partial compile and computes the system impedance seen from the scanning point over the specified frequency range. Built-in frequency scanning allows the RTDS Simulator to conveniently aid in identifying and reporting system resonance conditions.

Harmonic scan capability

Our new harmonic scan capability provides a white noise injection into the
network during the simulation. Harmonic waveforms of a frequency range
specified by the user (up to 9 kHz) are superposed and applied to the system.
The impedance response of the system in the frequency domain is then calculated by the component. A module for conveniently creating Bode plots and determining eigenvalue-based Nyquist stability criterion for the system is currently under development.

Sample cases for flywheel and pumped storage

RSCAD now features fully documented flywheel and pumped hydro storage sample cases, which provide a launch point for users looking to explore mechanical energy storage applications. The pumped hydro storage case is based on a variable speed doubly-fed induction machine system, with the machine, converters, and PWM firing pulse generation modelled in the Substep environment. The flywheel case models an additional mass added to the rotor of a permanent magnetic synchronous machine, and includes a back-to-back converter and firing pulse generator in the Substep environment. Both cases have average value model (AVM) versions, which reduce the quantity of simulation hardware required to run the case. The new cases can be found in the Samples directory.

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