Emulation of grid-forming inverters using real-time PC and 4-quadrant voltage amplifier

A test bed for the evaluation of novel control methods of inverters for renewable power generation is presented. The behavior of grid-following and grid-forming control in a test scenario is studied and compared.

Using a real-time capable control platform with a cycle time of 50?µs, control methods developed with Matlab/Simulink can be implemented. For simplicity, a three-phase 4?quadrant voltage amplifier is used instead of an inverter. Thus, the use of modulation and switched power semiconductors can be avoided. In order to show a realistic behavior of a grid-side filter, passive components can be automatically connected as L?, LC- or LCL-filter. The test bed has a nominal active power of 43.6?kW and a nominal voltage of 400?V.

As state-of-the-art grid-following control method, a current control in the d/q-system is implemented in the test bed. A virtual synchronous machine, the Synchronverter, is used as grid-forming control method. In combination with a frequency-variable grid emulation, the behavior of both control methods is studied in the event of a load connection in an island grid environment.