Abstract:In order to compensate for the delay of low pass filter on harmonic detection,the instantaneous reactive theory is analyzed by using current average method.Since traditional current average method has its defect,an improvement current average method is put forward.The method adopts different integral periods when filtering instantaneous AC component,which enhances response speed and detective precision and can detect the harmonic current accurately.Simulation results and analysis show that the active power filter adopting the improved average algorithm can detect and compensate for load harmonic current in real time,and reach perfect filtering effect,which is especially suitable for consumers demand of higher power quality.