METHOD FOR MEASURING REACTIVE POWER IN THREE-PHASE SYMMETRIC ELECTRICAL CIRCUIT Russian patent published in 2017 - IPC G01R21/06 

FIELD: measuring equipment.

SUBSTANCE: method for measuring reactive power in a three-phase symmetric electrical circuit involves the measurement of instantaneous currents and voltages at each phase. The measured instantaneous values of phase currents and voltages are scaled, then converted from the natural three-phase coordinate system to a two-phase α-β coordinate system. Based on the obtained current projections I_α, I_β and the stresses U_α, U_β at the coordinate α-β system is formed by the current vectors I_s and the voltage U_s: then the vector product is determined between the vectors I_s and U_s: Q_γ=I_S×U_S. The obtained projections of currents and voltages in αβ the coordinate system are multiplied Q₁=I_α⋅U_β and Q₂=-I_β⋅U_α, then they are added and multiplied by the number of phases: where is the estimate of the reactive power of the three-phase circuit. The transformation of phase currents and voltages from the natural three-phase coordinate system to the two-phase system is carried out according to the following expressions: where I_A, I_B, I_c - instantaneous phase currents; I_α, I_β - the projection of currents in the α-β coordinate system; U_A, U_B, U_C - instantaneous phase voltages; U_α, U_β - the projection of stresses in the α-β coordinate system.

EFFECT: improving the measurement accuracy.

2 cl, 2 tbl, 7 dwg