학술논문

Resolving Current Transformer Partial Saturation Problem: An Analytical Approach to Design the Flux Equalizing Winding
Document Type
Periodical
Source
IEEE Transactions on Power Delivery IEEE Trans. Power Delivery Power Delivery, IEEE Transactions on. 37(5):4145-4153 Oct, 2022
Subject
Power, Energy and Industry Applications
Current transformers
Relays
Windings
Conductors
Transformer cores
Magnetic flux
Circuit faults
CT error
equalizing winding
partial saturation
relay maloperation
stray flux
Language
ISSN
0885-8977
1937-4208
Abstract
Stray fluxes passing through the current transformer (CT) core produced by adjacent bus-bars and conductors or eccentric installation of primary conductors results in asymmetric magnetic flux distribution along the core. This may lead to exceeding the magnetic flux from its appropriate saturation level in some parts of the core, which is called partial saturation (PS) phenomenon. Under such a condition, CT error increases, and some relays maloperations may take place. This paper proposes a novel analytical approach to design flux equalizing winding (EW) for resolving such a problem. Moreover, PS occurrence in a core balance CT (CBCT) is analyzed using the finite element method (FEM), and its negative influence on a sensitive earth fault (SEF) relay is scrutinized as a case study. Simulation studies reveal that the proposed approach can prevent PS-related undesirable effects in a real power system.