Improving The Active Power Filter Performance With Control Delay And Dead-Time Effect Compensation

With the widely use of power electronic device the problem of harmonic distortion in power system becomes ever more important. Because of the good dynamic performance and compensation characteristic, active power filter (APF) gets the rapid development and in-depth research. Along with the research, we discovered that control delay and dead-time effect inevitably exist in the control of the APF. They are harmful to the compensation performance. In order to improve the APF performance, this paper traverses the formation cause and negative affection of control delay and dead-time effect, and brings forward the compensation method for them respectively.Performing the digital control algorithm, sampling the measurement signals and the PWM control, mainly causes the control delay. Because of this, the control is always late and the control system cannot react fast enough to rapid changes in the current reference. Consequently the performance of APF deteriorates. The scheme of hybrid active power filter with control delay compensation combines the hybrid filter and control delay compensation together. It is proposed to lead a control delay compensation module into the control system of APF, in the mean time a high-pass reactive filter is connected in parallel with the APF. By use of the high-pass filter the higher-order harmonics which sensitive to the control delay are restrained, and the negative affection of control delay is abated by control delay compensation module.