| 摘要 |
PROBLEM TO BE SOLVED: Toenable control of higher-order harmonic current which was impossible in prior out. SOLUTION: There is control delay in the control system of an active filter. Higher-order harmonic current can be controlled by controlling current early by a time equivalent to the control delay. In general, harmonic current component which flows to a load in a power system slowly varies, and the waveform does not vary so much up to the preceding several periods. Therefore, current can be controlled by using as a current command value data (n-α) periods ago, obtained by making the phase of the current detection data n periods ago (n: 1, 2, 3,...8 or so) by an amount equivalent to the control delay α(1>α>0). For this reason, a ring buffer is placed between a compensation current detection system and the current control system. The compensation current detection system writes the compensation current into the ring buffer, and the current control system reads the current waveform of a pointer (n-α) periods ago, that is, with its phase advanced by αperiods on the ring buffer, as a current command value ahead by α. Thus feed forward-like current control is exercised. |
