INSTANTANEOUS REACTIVE CURRENT DETECTOR

PURPOSE:To detect an instantaneous reactive current with a simple circuit by finding the instantaneous reactive current of a 3-phase power supply and multiplying the product of the current and a coefficient by a 3-phase sinusoidal wave. CONSTITUTION:A sinusoidal wave generator SG uses a synchronizing pulse to obtain a pulse mu voltage theta and generates a 3-phase sinusoidal wave of costheta, cos(theta-2/3pi) and cos(theta-4/3pi). An adder A1 obtains a current -(iu+iv)=iw by addition. The three-phase current and the 3-phase sinusoidal wave are multiplied by multipliers M1-M3, the result is added by an adder A2, the result is multiplied by a coefficient, and costheta and cos(theta-2/3pi) are multiplied by multipliers M4, M5, then 2-phase instantaneous reactive currents iuq, ivq are obtained, the both are added by an adder A3 to invert the polarity, then the 3-phase instantaneous reactive current is obtained.