Abstract
Modular Multilevel Converters in High Voltage Direct Current (MMC-HVDC) systems with Synchronous Reference Frame-Phase-Locked Loops (SRF-PLLs) have been extensively studied for power transmission networks. This paper investigates the impact of the Short Circuit Ratio (SCR) and SRF-PLL bandwidth on the small-signal stability of grid-connected MMC-HVDC systems. Small-signal state-space models of the systems were established, through which the impedance/admittance of the MMC-HVDC and power grid were calculated. An impedance/admittance-based stability analysis with generalized Nyquist stability criterion was then applied. The analysis results were compared and verified through non-linear time-domain simulation in PSCAD. This analysis demonstrates that the SRF-PLL bandwidth range that maintains stability is narrower for lower SCR conditions. This range is further constrained when there is a higher current output from the MMC-HVDC.
| Original language | English |
|---|---|
| Title of host publication | IET Powering Net Zero Conference 2024 |
| Publication status | Accepted/In press - 28 Jun 2024 |
Keywords
- GENERALIZED NYQUIST STABILITY CRITERION (GNC)
- MODULAR MULTILEVEL CONVERTER
- PHASE-LOCKED LOOP (PLL)
- SMALL-SIGNAL STABILITY
