Transient Synchronization Stability Analysis of Wind Farms with MMC-HVDC Integration Under Offshore AC Grid Fault

TL;DR

This paper analyzes the transient synchronization stability of offshore wind farms with MMC-HVDC during faults, proposing a new stability index and comparing stability improvement methods through simulations.

Contribution

It introduces a novel stability index for assessing transient synchronization stability and evaluates various stability improvement methods under fault conditions.

Findings

The stability index effectively predicts wind turbine resynchronization.

Four stability improvement methods are thoroughly compared.

Simulation results validate the effectiveness of the proposed index.

Abstract

The MMC-HVDC connected offshore wind farms (OWFs) could suffer short circuit fault (SCF), whereas their transient stability is not well analysed. In this paper, the mechanism of the loss of synchronization (LOS) of this system is analysed considering the whole system state from the fault-on to the post-fault, and the discussion on fault type and fault clearance is addressed as well. A stability index is proposed to quantify the transient synchronization stability (TSS) of the system, which is capable to not only estimate whether the wind turbine generators (WTGs) be able to get resynchronized with the offshore MMC after the fault is cleared, but also to evaluate the performance of stability improving methods as well. Finally, a scenario of six cases is tested on the PSCAD/EMTDC simulation platform, where the performances of four existing stability improving methods are thoroughly compared via both numerical simulation and the proposed stability index.