Inside a Grid-Following Inverter: The Control Loops
Grid-following inverter control: the cascaded PLL, current and outer loops, dq decoupling, IMC tuning, and why fault current is limited. With worked math.
Inside a Grid-Forming Inverter: Droop, VSM and Power Synchronization
Grid-forming control: droop, virtual synchronous machine and power synchronization, the shared voltage/current cascade, with worked droop and inertia math.
Grid-Forming Inverter Requirements: Specs and Compliance Testing
Grid-forming inverter requirements explained: GC0137, AEMO, IEEE 2800.2 and UNIFI specs, the key tests, and a worked phase-jump current-limit example.
Stability Screening for IBR-Rich Systems Using SCR, RMS, and EMT
Stability screening for IBR-rich systems: SCR and WSCR limits, when to escalate from RMS to EMT, with a worked WSCR example and real ERCOT and AEMO cases.
SRF-PLL Design: Synchronizing an Inverter to the Grid
SRF-PLL design for grid synchronization: the structure, second-order Kp and Ki tuning, the bandwidth trade-off, weak-grid limits, and DSOGI variants.
