| 摘要 |
PURPOSE:To detect a reactive power quickly by adding a ripple component of an effective power value produced by the multiplying the voltage with current after advancing the phase by 1/4 period of the ripple period to the reactive power value produced by the multiplying of the voltage wave form by 90 deg. and the current. CONSTITUTION:A line voltage is inputted as (es) to a phase shifter (ps) by a voltage transformer, whereby it is delayed by 90 deg. to (e's). Fluctuating current is transformed to (iL) by a current transformer, and is inputted to multipliers X1 and X2. The voltage (es) is inputted to the multiplier X2 as well. In the multiplier X1, the voltage (e's) and the current (iL) are multiplied, and the q(t) which is the result thereof is inputted to an adder A. The voltage (es) an the current (iL) are multiplied by the multiplier X2 and the p(t) which is the result thereof is inputted to a differentiator D. Only the ripple component of the p(t) is detected at 1/4 period advanced phase by differentiating the same, and this turns out that it is detected at 1/2 period advanced phase of the original ripple part of the q(t). These are added by the adder A, whereby the output Q(t) thereof is detected with the DC component. |
