Patent ID: 8271215

Claim:
Method of measurement of the imbalance power of an electrical facility or system which comprises: i) acquiring instantaneous values of voltage (v A , v B , v C ) and current (i A , i B , i C ) of each of the phases A, B, C of the electrical facility or system, and decomposing them into their components at fundamental frequency (v A1 , v B1 , v C1 ), (i A1 , i B1 , i C1 ); ii) obtaining effective values of voltage (V A1 , V B1 , V C1 ) and current (I A1 , I B1 , I C1 ) and angles of initial phase displacement (φ A1 , φ B1 , φ C1 ) between voltage and current, for the fundamental frequency; iii) starting from the active and reactive powers, an imbalance power phasor (Ā U ) is obtained ( 4 ) according to the following expression: Ā U =√{square root over (2)}( p ·|P A +a 2 P B +aP C |+ q ·|Q A +a 2 Q B +aQ C |) wherein a=1 |120° and p and q are orthogonal unit phasors and wherein said active powers (P A , P B , P C ) and reactive powers (Q A , Q B , Q C ) are obtained starting from the effective values for the fundamental frequency obtained in step ii), for each one of the phases according to the following expression: P A =V A1 ·I A1 ·cos φ A1 Q A =V A1 ·I A1 ·sin φ A1 P B =V B1 ·I B1 ·cos φ B1 Q B =V B1 ·I B1 ·sin φ B1 P C =V C1 ·I C1 ·cos φ C1 Q C =V C1 ·I C1 ·sin φ C1 or starting from the effective values for the fundamental frequency obtained in step ii), obtaining effective values of positive sequence and fundamental frequency voltage (V A1+ , V B1+ , V C1+ ) and phase displacement angles (φ A1+ , φ B1+ , φ C1+ ) between voltage and current for the fundamental frequency, for each one of the phases according to the following expression: P A =V A1+ ·I A1 ·cos φ A1+ Q A =V A1+ ·I A1 ·sin φ A1+ P B =V B1+ ·I B1 ·cos φ B1+ Q B =V B1+ ·I B1 ·sin φ B1+ ; and P C =V C1+ ·I C1 ·cos φ C1+ Q C =V C1+ ·I C1 ·sin φ C1+ iv) starting from the active and reactive powers, an imbalance power phasor (Ā U ) is obtained ( 4 ) according to the following expression: Ā U =√{square root over (2)}( p ·|P A +a 2 P B +aP C |+ q ·| Q A +a 2 Q B +a Q C |) where a=I |120° and p and q are orthogonal unit phasors.