10-26 L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUALDISTANCE ELEMENTS CHAPTER 10: THEORY OF OPERATION10Table 10-4: Directional quadrilateral ground distance functionsTable 10-5: Non-directional mho phase distance functionsTable 10-6: Non-directional mho ground distance functionsTable 10-7: Non-directional quadrilateral phase distance functionsTable 10-8: Non-directional quadrilateral ground distance functions10.3.4 Fast distance algorithmIn order to improve operating speed of the phase and ground distance zone 1 and zone 2 elements under CVT transientconditions for high SIRs up to 60, a fast distance algorithm is implemented in the relay. This algorithm uses a weightedaverage digital filtering technique and runs in parallel with a regular distance algorithm, which uses a fixed digital CVTfiltering technique. The fast distance algorithm applies the same comparators as a regular distance algorithm.Characteristic Comparator inputs Limit angleReactance I × Z – V j × I_0 × e jΘ or j × I_2× e jΘ COMP LIMITDirectional I_0 × Z D V_1M DIR COMP LIMITDirectional I_2 × Z D V_1M DIR COMP LIMIT (removed when 3I_0 > OC SUPV and I_2 < CUTOFF)Right Blinder I × Z R – V I × Z R 90°Left Blinder I × Z L – V I × Z L 90°Fault-type I_0 I_2 50° (removed during open pole conditions or when 3I_0 > OC SUPVand I_2 < CUTOFF)Zero-sequence I_0 × Z D –V_0 90° (zones and higher only; removed for zones 2 and higher duringopen pole conditions)Characteristic Comparator inputs Limit angleOffset mho I × Z – V V-I × Z REV COMP LIMITFault type NOT SLG See the Fault Type Characteristic section Removed during open pole conditionsCharacteristic Comparator inputs Limit angleOffset mho I × Z – V V-I × ZREV COMP LIMITFault-type I_0 I_2 50° (removed during open pole conditions or when 3I_0 > OCSUPV and I_2 < CUTOFF)Characteristic Comparator inputs Limit angleForward Reactance I × Z – V I × Z COMP LIMITReverse Reactance I × Z REV – V I × Z REV COMP LIMITRight Blinder I × Z R – V I × Z R 90°Left Blinder I × Z L – V I × Z L 90°Fault type NOT SLG See the Fault Type Characteristic section Removed during open pole conditionsCharacteristic Comparator inputs Limit angleForward Reactance I × Z – V j × I_0 × e jΘ or j × I_2× e jΘ COMP LIMITReverse Reactance I × ZREV – V –j × I_0 × e jΘ or –j ×I_2 × e jΘ COMP LIMITRight Blinder I × ZR – V I × Z R 90°Left Blinder I × ZL – V I × Z L 90°Fault-type I_0 I_2 50° (removed during open pole conditions or when 3I_0 > OCSUPV and I_2 < CUTOFF)
