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 during synchronization process.
Figure 10.11 Experimental results during the normal operation of the DFIG‐VSG.
Figure 11.1 Three typical earthing networks in low‐voltage systems.
Figure 11.2 Generic equivalent circuit for analyzing leakage currents.
Figure 11.3 Equivalent circuit for analyzing leakage current of a grid‐tied converter with a common AC and DC ground.
Figure 11.4 A conventional half‐bridge inverter.
Figure 11.5 A transformerless PV inverter.
Figure 11.6 Controller for the neutral leg.
Figure 11.7 Controller for the inverter leg.
Figure 11.8 Real‐time simulation results of the transformerless PV inverter in Figure 11.5(a).
Figure 12.1 STATCOM connected to a power system.
Figure 12.2 A typical two‐axis control strategy for a PWM based STATCOM using a PLL.
Figure 12.3 A synchronverter based STATCOM controller.
Figure 12.4 Single‐line diagram of the power system used in the simulations.
Figure 12.5 Detailed model of the STATCOM used in the simulations.
Figure 12.6 Connecting the STATCOM to the grid.
Figure 12.7 Simulation results of the STATCOM operated in different modes.
Figure 12.8 Transition from inductive to capacitive reactive power when the mode was changed at t = 3.0 s from the Q‐mode to the V‐mode.
Figure 12.9 Simulation results of the STATCOM operated with a changing grid frequency.
Figure 12.10 Simulation results of the STATCOM operated with a changing grid voltage.
Figure 12.11 Simulation results with a variable system strength.
Figure 13.1 Per‐phase diagram with the Kron‐reduced network approach.
Figure 13.2 Phase portraits of the controller.
Figure 13.3 The controller to achieve bounded frequency and voltage.
Figure 13.4 E+ surface (upper) and E− surface (lower) with respect to Ps and Qs.
Figure 13.5 Illustration of the areas characterized by E+ lines and E− lines.
Figure 13.6 Illustration of the area where a unique equilibrium exists.
Figure 13.7 Real‐time simulation results comparing the original (SV) with the improved self‐synchronized synchronverter (improved SV).
Figure 13.8 Phase portraits of the controller states in real‐time simulations.
