4–84 889 GENERATOR PROTECTION SYSTEM – INSTRUCTION MANUALSYSTEM CHAPTER 4: SETPOINTSPhase Shift CompensationFrom the transformer example, the phase reference winding is winding 2 (i.e.,wf = 2). Thephase compensation angle for each winding is then calculated as follows (Rotation =“ABC”):φcomp[1] = -30°– 0° = -30° = 30° lagφcomp[2] = -30° – (–30°) = 0°The non-reference Wye winding will be rotated by -30° degrees to be in-phase and matchthe currents from the Delta winding.Per figure: Two-winding transformer connections for phase compensation angle of 30 lag,the relay will use the following phase and zero-sequence compensation equations:Winding 1 (Wye – grounded neutral):IAp [w]= (1/√3)IA [w] - (1/√3)IC [w]IBp [w]= (1/√3)IB [w] - (1/√3)IA[w]ICp [w]= (1/√3)IC [w] - (1/√3)IB [w]Winding 2 (Delta):IAp[w] = IA [w]IBp[w] = IB [w]ICp[w]= IC [w]The complete compensated winding 1 and winding 2 currents would be as follows:The differential and restraint currents would be as follows:Differential currents:IdA = 0 x CTIdB = 0 x CTIdC = 0 x CTRestraint currents:IrA = 0.209 x CTIrB = 0.209 x CTIrC = 0.209 x CT
