Power Electronics-Enabled Autonomous Power Systems. Qing-Chang Zhong

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 co...Figure 11.4 A conventional half‐bridge inverter. (a) Topology. (b) Average cir...Figure 11.5 A transformerless PV inverter. (a) Topology. (b) Average circuit m...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...

      12 Chapter 12Figure 12.1 STATCOM connected to a power system. (a) Sketch of the connection....Figure 12.2 A typical two‐axis control strategy for a PWM based STATCOM using ...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. (a)

. (b)

. (c) Real power. ...Figure 12.7 Simulation results of the STATCOM operated in different modes. (a)...Figure 12.8 Transition from inductive to capacitive reactive power when the mo...Figure 12.9 Simulation results of the STATCOM operated with a changing grid fr...Figure 12.10 Simulation results of the STATCOM operated with a changing grid v...Figure 12.11 Simulation results with a variable system strength. (a)

. (b)

....

      13 Chapter 13Figure 13.1 Per‐phase diagram with the Kron‐reduced network approach.Figure 13.2 Phase portraits of the controller. (a) The frequency dynamics. (b)...Figure 13.3 The controller to achieve bounded frequency and voltage.Figure 13.4

surface (upper) and

surface (lower) with respect to

and

.Figure 13.5 Illustration of the areas characterized by

lines and

lines.Figure 13.6 Illustration of the area where a unique equilibrium exists. (a) Wh...Figure 13.7 Real‐time simulation results comparing the original (SV) with the ...Figure 13.8 Phase portraits of the controller states in real‐time simulations....

      14 Chapter 14Figure 14.1 The controller of the original synchronverter.Figure 14.2 Active power regulation in a conventional synchronverter after dec...Figure 14.3 Properties of the active power loop of a conventional synchronvert...Figure 14.4 VSM with virtual inertia and virtual damping.Figure 14.5 The small‐signal model of the active‐power loop with a virtual ine...Figure 14.6 Implementations of a virtual damper. (a) Through impedance scaling...Figure 14.7 A VSM in a microgrid connected to a stiff grid.Figure 14.8 Normalized frequency response of a VSM with reconfigurable inertia...Figure 14.9 Effect of the virtual damping (

s).Figure 14.10 A microgrid with two VSMs.Figure 14.11 Two VSMs operated in parallel with

s.Figure 14.12 Two VSMs operated in parallel with

s and

s.Figure 14.13 Simulation results under a ground fault with

s. (a) Normalized ...Figure 14.14 Experimental results with reconfigurable inertia and damping. (a)...Figure 14.15 Experimental results from the original synchronverter for compari...Figure 14.16 Experimental results showing the effect of the virtual damping wi...Figure 14.17 Experimental results when two VSMs with the same inertia time con...Figure 14.18 Experimental results when two VSMs with the same inertia time con...Figure 14.19 Experimental results when two VSMs with different inertia time co...Figure 14.20 Experimental results when the two VSMs operated as the original S...

      15 Chapter 15Figure 15.1 Block diagrams of a conventional PLL. (a) Operational concept. (b)...Figure 15.2 Enhanced phase‐locked loop (EPLL) or sinusoidal tracking algorithm...Figure 15.3 Power delivery to a voltage source through an impedance.Figure 15.4 Conventional droop control scheme for an inductive impedance. (a) ...Figure 15.5 Conventional droop control strategies. (a) For resistive impedance...Figure 15.6 Linking the droop controller in Figure 15.4(b) and the (inductive)...Figure 15.7 Droop control strategies in the form of a phase‐locked loop. (a) W...Figure 15.8 The conventional droop controller shown in Figure 15.4(a) after ad...Figure 15.9 The synchronization capability of the droop controller shown in Fi...Figure 15.10 Connection of the droop controlled inverter to the grid.Figure 15.11 Regulation of the grid frequency and voltage in the droop mode.Figure 15.12 Robustness of synchronization against DC‐bus voltage changes. (a)...Figure 15.13 System response when the operation mode was changed.

      16 Chapter 16Figure 16.1 A single‐phase inverter. (a) Used for physical implementation. (...Figure 16.2 Controller to achieve a resistive output impedance.Figure 16.3 Controller to achieve a capacitive output impedance.Figure 16.4 Typical output impedances of L‐, R‐, and C‐inverters.Figure 16.5 Two R‐inverters operated in parallel.Figure 16.6 Conventional droop control scheme for R‐inverters.Figure 16.7 Experimental results: two R‐inverters in parallel with conventio...Figure 16.8 Robust droop controller for R‐inverters.Figure 16.9 Experimental results for the case with a linear load when invert...Figure 16.10 Experimental results for the case with a linear load when inver...Figure 16.11 Experimental results for the case with the same per‐unit impeda...Figure 16.12 Experimental results with a nonlinear load: with the robust dro...Figure 16.13 Robust droop controller for C‐inverters.Figure 16.14 Experimental results of C‐inverters (left column) and R‐inverte...Figure 16.15 Experimental results of C‐inverters (left column) and R‐inverte...Figure 16.16 Robust droop controller for L‐inverters.Figure 16.17 Experimental results of L‐inverters with a linear load: with th...Figure 16.18 Experimental results of L‐inverters with a nonlinear load: with...

      17 Chapter 17Figure 17.1 The model of a single‐phase inverter.Figure 17.2 The closed‐loop system consisting of the power flow model of an ...Figure 17.3 Interpretation of transformation matrices

and

. (a)

. (b)

....Figure 17.4 Interpretation of the universal transformation matrix

.Figure 17.5 Universal droop controller.Figure 17.6 Rel‐time simulation results of three inverters with different ty...Figure 17.7 Experimental set‐up consisting of an L‐inverter, an R‐inverter, ...Figure 17.8 Experimental results with the universal droop controller. (a)

...

      18 Chapter 18Figure 18.1 The self‐synchronized universal droop controller.Figure 18.2 Experimental results of self‐synchronization with the R‐inverter...Figure 18.3 Experimental results when connecting the R‐inverter to the grid....Figure 18.4 Experimental results with the R‐inverter: performance during the...Figure 18.5 Experimental results with the R‐inverter: regulation of system f...Figure 18.6 Experimental results with the R‐inverter: change in the DC‐bus v...Figure 18.7 Experimental results of self‐synchronization with the L‐inverter...Figure 18.8 Experimental results with the L‐inverter: connection to the grid...Figure 18.9 Experimental results with the L‐inverter: performance during the...Figure 18.10 Experimental results with the L‐inverter: regulation of system ...Figure 18.11 Experimental results with the L‐inverter: