Summary
The widespread integration of DERs through power-electronics-based converters introduces significant challenges during fault scenarios. Asymmetric faults — the predominant fault type in distribution systems — cause severe voltage disturbances at the DER point of common coupling (PCC), potentially triggering cascading disconnections. Existing LVRT strategies, including those specified in recent grid codes (VDE-AR-N 4120, GB/T 29319-2024), suffer from two critical limitations: neglecting cross-sequence coupling effects, and lacking communication-free multi-converter coordination capability.
Read more Read lessThis paper addresses these limitations through three contributions: 1) coupled sequence network models for three asymmetric fault types, incorporating sequence coupling and multiconverter cooperation dynamics; 2) an equality-constrained RLS-based online parameter estimation method enabling communication-free coordination, with convergence within approximately 20 ms; and 3) a Sequence-Coupled Coordinated Voltage Support (SCCVS) strategy optimizing dual-sequence current references to maximize PCC voltage support.
Simulation validation on a modified IEEE 33-bus system demonstrates that the proposed
SCCVS strategy achieves superior voltage support performance compared to existing LVRT strategies and Balanced Positive Sequence Control (BPSC) across all three asymmetric fault scenarios, with significantly improved voltage balance by simultaneously addressing sequence coupling and multi-converter coordination. Topology analysis further confirms that while radial networks achieve better voltage support than ring configurations, the SCCVS strategy consistently outperforms existing methods in both cases. Practical considerations including R/X ratio, fault severity, and measurement noise are discussed, with future Power
Hardware-in-the-Loop (PHIL) validation planned.
Additional informations
| Publication type | Session Materials |
|---|---|
| Reference | C6_12507_2026 |
| Publication year | |
| Publisher | CIGRE |
| Country | China, People's Republic of |
| Study committees | |
| File size | 3 MB |
| Price for non member | 30 € |
| Price for member | 30 € |
Authors
QIU Rui - Wuhan University; LIU Chengxi - Wuhan University
Keywords
Asymmetrical Faults, Voltage Support, External System Estimation
