Low-Voltage Ride Through of a Grid-Forming Converter using the Per-Phase Power Control

The paper describes a technique for safe low-voltage ride-through of grid-forming converters that use the per-phase power control. The per-phase power control features active and reactive output power tracking for each of the three phases of a power electronic inverter during grid-connected operation and smooth transitions and operation in islanded conditions. As with any other grid-forming technique, dedicated provisions must be applied to ensure safe and stable operation across a voltage dip imposed at its output terminals. The technique devised and demonstrated herein allows to i) limit the output currents during voltage disturbances; ii) avoid transient instability and reduce post-fault transients; iii) preserve the voltage regulation performances; iv) support the islanded operation. These features are demonstrated by means of simulation results, and validated in experimental tests involving a 3 kVA grid-forming converter.