Transient modeling of saturated core fault current limiters

A saturated core fault current limiter (FCL) essentially

utilizes the dynamic and nonlinear magnetic behavior of

steel cores to operate as a variable reactor. However, the nonlinear

characteristic of magnetic materials has made modeling this

unique device a difficult task. Hence, experimental measurements

and finite-element method (FEM) analysis are the most common

techniques used to characterize the transient behavior of the

device. Both of these techniques, while accurate, cannot be used

to analyze the transient electrical behaviour of FCLs in complex

power systems, particularly when investigating power system

switchgear behavior during fault events. FEM-based FCL modelling,

despite its usefulness as a design verification tool, cannot

be easily coupled to all electromagnetic transient programs that

are in use today. This paper presents two modeling approaches to

represent the saturated core FCL in transient network simulators:

1) the nonlinear reluctance model and 2) the nonlinear inductance

model. Both models are implemented in PSCAD/EMTDC and are

validated by experimental results of a single-phase prototype

saturated core FCL, where excellent agreement between the

experimental and the modelling approaches is achieved.