Figure 4.2 The power part of a synchronverter is a basic inverter.
Figure 4.3 The electronic part of a synchronverter without control.
Figure 4.4 The electronic part of a synchronverter with the function of frequency and voltage control, and real and active power regulation.
Figure 4.5 Operation of a synchronverter under different grid frequencies (left column) and different load conditions (right column).
Figure 4.6 Experimental setup with two synchronverters.
Figure 4.7 Experimental results in the set mode: output currents with 2.25 kW real power.
Figure 4.8 Experimental results in the set mode: output currents (left column) and the THD of phase‐A current (right column) under different real powers.
Figure 4.9 Experimental results in the droop mode: primary frequency response.
Figure 4.10 Experimental results: the currents of the grid, VSG, and VSG2 under the parallel operation of VSG and VSG2 with a local resistive load.
Figure 4.11 Real power P and reactive power Q during the change in the operation mode.
Figure 4.12 Transient responses of the synchronverter.
Figure 5.1 Structure of an idealized three‐phase round‐rotor synchronous motor.
Figure 5.2 The model of a synchronous motor.
Figure 5.3 PWM rectifier treated as a virtual synchronous motor.
Figure 5.4 Directly controlling the power of a rectifier.
Figure 5.5 Controlling the DC‐bus voltage of a rectifier.
Figure 5.6 Simulation results when controlling the power.
Figure 5.7 Simulation results when controlling the DC‐bus voltage.
Figure 5.8 Experimental results when controlling the power.
Figure 5.9 Experimental results when controlling the DC‐bus voltage.
Figure 6.1 Integration of a PMSG wind turbine into the grid through back‐to‐back converters.
Figure 6.2 Controller for the RSC.
Figure 6.3 Controller for the GSC.
Figure 6.4 Dynamic response of the GSC.
Figure 6.5 Dynamic response of the RSC.
Figure 6.6 Real‐time simulation results with a grid fault appearing at t = 6 s for 0.1 s.
Figure 7.1 Conventional (DC) Ward Leonard drive system.
Figure 7.2 AC Ward Leonard drive system.
Figure 7.3 Mathematical model of a synchronous generator.
Figure 7.4 Control structure for an AC WLDS with a speed sensor.
Figure 7.5 Control structure for an AC WLDS without a speed sensor.
Figure 7.6 An experimental AC drive.
Figure 7.7 Reversal from a high speed without a load.
Figure 7.8 Reversal from a high speed with a load.
Figure 7.9 Reversal from a low speed without a load.
Figure 7.10 Reversal from a low speed with a load.
Figure 7.11 Reversal at an extremely low speed without a load.
Figure 7.12 Reversal from a high speed without a load (without a speed sensor).
Figure 7.13 Reversal from a high speed with a load (without a speed sensor).
Figure 8.1 Typical control structures for a grid‐connected inverter.
Figure 8.2 A compact controller that integrates synchronization and voltage/frequency regulation together for a grid‐connected inverter.
Figure 8.3 The per‐phase model of an SG connected to an infinite bus.
Figure 8.4 The controller for a self‐synchronized synchronverter.
Figure 8.5 Simulation results: under normal operation.
Figure 8.6 Simulation results: connection to the grid.
Figure 8.7 Comparison of the frequency responses of the self‐synchronized synchronverter (f) and the original synchronverter with a PLL (f with a PLL).
Figure 8.8 Dynamic performance when the grid frequency increased by 0.1 Hz at 15 s (left column) and returned to normal at 30 s (right column).
Figure 8.9 Simulation results under grid faults: when the frequency dropped by 1% (left column) and the voltage dropped by 50% (right column) at t = 36 s for 0.1 s.
Figure 8.10 Experimental results: when the grid frequency was lower (left column) and higher (right column) than 50 Hz.
Figure 8.11 Experimental results of the original synchronverter: when the grid frequency was lower than 50 Hz (left column) and higher than 50 Hz (right column).
Figure 8.12 Voltages around the connection time: when the grid frequency was lower (left column) and higher (right column) than 50 Hz.
Figure 9.1 Controlling the rectifier DC‐bus voltage without a dedicated synchronization unit.
Figure 9.2 Controlling the rectifier power without a dedicated synchronization unit.
Figure 9.3 Simulation results when controlling the DC bus voltage.
Figure 9.4 Grid voltage and control signal.
Figure 9.5 Grid voltage and input current.
Figure 9.6 Simulation results when controlling the real power.
Figure 9.7 Experiment results: controlling the DC‐bus voltage.
Figure 9.8 Experiment results: controlling the power.
Figure 10.1 Typical configuration of a turbine‐driven DFIG connected to the grid.
Figure 10.2 A model of an ancient Chinese south‐pointing chariot (Wikipedia 2018).
Figure 10.3 A differential gear that illustrates the mechanics of a DFIG, where the figure of the differential gear is modified from (Shetty 2013).
Figure 10.4 The electromechanical model of a DFIG connected to the grid.
Figure 10.5 Controller to operate the GSC as a GS‐VSM.
Figure 10.6 Controller to operate the RSC as a RS‐VSG.
Figure 10.7 Connection of the GS‐VSM to the grid.
Figure 10.8 Synchronization and connection of the RS‐VSG to the grid.
Figure 10.9 Operation of the DFIG‐VSG.
Figure 10.10 Experimental results of the DFIG‐VSG