Digital low-impedance bus differential protection with reduced requirements for CTs

Considerations for differential protection in LV buses

“…They provide the following advantages: • No need for dedicated CTs • Automatic CT ratio compensation • Advanced algorithms supplement the percent differential protection function making the relay very secure • Able to protect re-configurable busbars as the dynamic bus replica (bus image) can be accomplished in software without physically switching secondary current circuits • Integrated Breaker-Fail (BF) function for back-up protection • Distributed communication based system architectures replaces CT wires with fiber or Ethernet type wiring Algorithms for bus bar protection [1] are implemented by sample by sample comparison or comparison of calculated current phasors. The main difficulty in bus differential protection is that significant differential current may appear due to saturation of CTs on large external faults .…”

Incoming and Outgoing Ct Readings Based Ai Techniques for Bus Bar Differential Protection Faults Analysis

“…The testing will be on different faults types, faults resistances, fault inception time and different fault location. The results are recorded and presented in Table ( Tables (3), (4), (5) and (6) show the output of ANFIS and ANN controllers when the power system parameters changed. The ANFIS and ANN outputs for all testing fault cases were 1 for internal fault and 0 for external fault.…”

“…Slow fault clearing results additionally in extensive damage at the fault location as a consequence of the generally high concentration of short circuit power at station buses. More than with other circuit protection methods intensified emphasis is therefore put on the essential requirements of speed and stability [3] .A further important point to consider is through -fault stability with current transformer saturation as illustrated in [4][5][6][7]. The successful protection can be achieved subject to compliance with the following as presented in [8,9] : a) Selectivity, trip only the faulted equipment.…”

“…A low -impedance bus bar protection operates during CT saturation by using a principle, which discriminates between saturated and un saturated wave forms. Recently, many novel differential techniques have been proposed to overcome CT saturation [4][5][6][7]. For external faults, the differential current should be zero, but errors caused by CT saturation can result in a non zero value.…”

Development of a New Bus Zone Identification Algorithm Based on Phase Angle Comparison Using Sequence Components of Currents

“…which increases its complexity and cost. Kasztenny et al [12] and Kasztenny and Cardenas [13] proposed low impedance directional protection and phasesegregated digital busbar protection solutions. Narendra et al [14] presented a scheme based on combination of phase angle comparison and differential current for busbar and transformers.…”