Comparative assessment of four low voltage fault ride through techniques (LVFRT) for wind energy conversion systems (WECSs)

This paper presents a comparative assessment of four low voltage fault ride through (LVFRT) techniques that alleviate the effects of power imbalance during AC network faults for voltage source converter (VSC)-based wind energy conversion systems (WECSs). The techniques appraised include a software-based coordinated control (CC) technique, commercially available dumping resistor (DR) technique, and two energy storage techniques, namely, superconductive magnetic energy storage (SMES) and supercapacitor energy storage (SCES). The techniques presented are technically viable solutions for alleviating impacts of AC network faults on the WECS. The techniques have previously been assessed by performance-based metrics, whereas this paper aims to form a more comprehensive assessment by expanding the scope from the performance-based comparison to include economic considerations and practical limitations. Based on qualitative review of technically viable designs, this study presents quantitative substantiation with time-domain simulations of symmetrical and asymmetrical AC network faults. The comparative assessment is formulated based on assessing key performance metrics including grid code compliance, electrical and mechanical stress reduction, LVFRT response speed, hardware implementation, system efficiency and investment reduction. The assessment findings suggest that a performance-based study fails to highlight the potential financial and practical barriers that may exist regarding the implementation of the LVFRT solutions especially with energy storage-based techniques. However, the flexibility, benefits and increasing feasibility regarding energy storage systems may make them a preferred option for LVFRT of critical WECSs.