This presentation introduces fast simulation methods for assessing harmonic compliance of inverter-based resource (IBR) plants that is necessary for receiving an energization (EON), interim (ION), and finale (FON), operational notification, for grid-connection of the IBR plants to the transmission grid. Generally, the harmonic compliance shall be proven by simulation studies applying harmonic impedance envelopes representing various operation regimes of the meshed transmission grid and provided by the grid operator.

The harmonic impedance envelopes may range from tens ohms up to several thousand ohms with a step by one ohm for each relevant integer harmonic and interharmonic order. Such studies shall be fully completed and approved by the grid operator prior to granting operational notifications.

Fastest-possible completion of the harmonic compliance studies and high accuracy of the results are essential for the IBR plant developers to obtain the operation notifications.

The first presented fast method allows expediting the simulation time by omitting slow processes by many repeated, embedded, load-flow and harmonic load-flow commands on large harmonic impedance envelopes with a required resolution. The method applies fast arithmetical operations on independent variables to identify the area within the harmonic impedance envelope with the largest harmonic voltages and then, reduce the number of the embedded commands to be executed. The first method reduces the simulation time up to 65 times with the largest benefit for the largest envelopes.

The second fast method applies interpolation through critical points within the envelope to calculate the largest harmonic voltage. The second method simulates up to 20 times faster than the first method.

The third fast method combines the two first methods. This presentation will demonstrate the three methods using anonymized, real-life, examples and propose possible areas of applications.