Impact of DFIG‐based wind turbine's fault current on distance relay during symmetrical faults

Abstract

As a new highly penetrated power source of modern power systems, doubly fed induction generator (DFIG)-based wind turbine (WT) has a different fault current contribution when compared with a synchronous generator. DFIG-based WT's fault current has significant impacts on distance relay's performances and may result in maloperation. In this study, the impacts of DFIG-based WT's fault current on the dynamic performances of two typical distance protection elements, mho and polarisation, are studied in terms of EMTP simulations and fault current expressions in symmetrical fault scenarios. It is discovered that the zone-1 distance relays of the lines connecting to DFIG-based wind power plants tend to overreach. Also, the following analysis indicates that the transient components of DFIG-based WT's fault current and the phasor estimation unit are the underlying reasons. With those understanding, this study is expected to help design new setting methods and for distance protection in power systems integrating wind power plants to prevent this kind of possible overreach. System description and relay settings System overviewThe power system studied in this paper is shown in Fig. 1. It is a typical scenario that the DFIG-based wind power plant connects with a high-level power grid through double-circuit lines. The dynamic performance of the digital distance relay DR1-2 is the main focus of the following studies.

Short-Circuit Modeling of DFIG-Based WTG in Sequence Domain Considering Various Fault- Ride-Through Requirements and Solutions

“…The fault behavior of DFIG-based WTGs is more complex than that of conventional synchronous generators (SGs) [3] and varies when adjusted to comply with grid codes [4]. This different fault current response introduces technical challenges in short circuit analysis leading to maloperation and miscoordination [5]- [8] when assumed to behave like a conventional source. The development of accurate models for the DFIG-based WTG is a critical step to perform accurate short circuit studies in modern Y. Chang and I. Kocar are with the Hong Kong Polytechnic University, Hong Kong SAR, China (e-mail: yuanzhu.chang@polyu.edu.hk; ilhan.kocar@polyu.edu.hk).…”