The influence of current transformer saturation on the longitudinal differential protection of transmission lines

AbstractThis paper presents a phasor-distance based faulty phase detection and fault classification technique for parallel transmission lines. Detection and classification of faulty phase(s) have been carried out by deriving indices from the change in phasor values of current with a distance of one cycle. The derived indices have zero values during normal operating conditions whereas the index corresponding to the faulty phase exceeds the pre-defined threshold in case of occurrence of a fault. A separate ground detection algorithm has been utilized for the identification of involvement of ground in a faulty situation. The performance of the proposed technique has been evaluated for intra-circuit, inter-circuit and simultaneous faults with wide variations in system and fault conditions. The suggested technique has been evaluated for over 23,000 diversified simulated fault cases as well as 14 recorded real fault events. The performance of the proposed technique remains consistent under Current Transformer (CT) saturation as well as different amount and direction of power flow. Moreover, suitability to different power system network has also been studied. Also, faults having fault current less than pre-fault conditions have been detected accurately. The results obtained suggest that it is able to detect faulty phases as well as classify faults within quarter-cycle from the inception of fault with impeccable accuracy. Besides, as modern digital relays have been already equipped with phasor computation facility, phasor-based technique can be easily incorporated with relative ease. At last, a comparative evaluation suggests its superiority in terms of fault classification accuracy, fault detection time, diversify fault scenarios and computational requirement among other existing techniques.

Download Full-text

Design and optimization for current transformer core based on magnetic field analysis

Journal of Computational Methods in Sciences and Engineering ◽

10.3233/jcm-204849 ◽

2021 ◽

pp. 1-14

Author(s):

Guoyong Zhang ◽

Jing Luo ◽

Lifu He ◽

Xiudong Zhou ◽

Shaosheng Fan

Keyword(s):

Transmission Lines ◽

Great Influence ◽

Current Transformer ◽

Magnetic Core ◽

Field Analysis ◽

Core Material ◽

Design And Optimization ◽

Magnetic Field Analysis ◽

Acquisition Device ◽

On Line

In order to ensure the safety and reliability of power system, more and more monitoring and maintenance equipment on transmission lines are being used. However, these equipment would not work without the supply of power. At present, the current transformer has been widely used in the on line power acquisition device. As an important part of the current transformer, the performance magnetic core has great influence on the power acquisition. In this paper, the core parameters of the current transformer in the on-line power acquisition device are designed, and the parameters such as core material and air gap length are optimized and verified by simulation as well.

Download Full-text

New current transformer for bus differential protection

Electrical Engineering ◽

10.1109/ee.1941.6434603 ◽

1941 ◽

Vol 60 (12) ◽

pp. 1180-1187

Author(s):

L. F. Kennedy ◽

A. T. Sinks

Keyword(s):

Current Transformer ◽

Differential Protection

Download Full-text