| In smart grid,renewable energy is integrated through power electronic interface,which leads to the increase of various unstable loads.The exponential growth of Interharmonics has attracted great attention of power supply system.Due to the non ideal characteristics of voltage source,harmonic current will cause voltage distortion.All kinds of nonlinear loads and other asymmetric loads will bring huge disturbance to the power supply system.The relatively fast dynamic response and mature compensation method of active power filter are widely used,which can keep the harmonic interference at a reasonable level.In the aspect of harmonic and interharmonic current detection,the traditional PLL can not accurately lock the phase in the case of three-phase power grid distortion,harmonic and interharmonic imbalance.In this paper,a phase-locked loop in synchronous coordinates is designed,which has certain adaptability.The simulation results show that the influence of harmonic and interharmonic interference is reduced.In the aspect of harmonic and interharmonic current tracking control,space vector pulse width modulation(SVPWM)has the advantages of fixed switching frequency,high utilization rate of DC bus voltage and good control performance,which has been widely used in three-phase voltage source inverter.Active power filter(APF)is also a kind of current controlled inverter(VSI),which can form a reasonable match with space vector pulse width modulation(SVPWM)technology.Traditional active power filter(APF)based on space vector pulse width modulation(SVPWM)needs complex trigonometric calculation and sector identification to generate compensation signal,which has large amount of calculation and slow compensation response time.Based on the concept of effective time,an improved shunt active power filter based on SVPWM technology is proposed.The concept of effective time saves the trigonometric calculation and sector identification,thus reducing the amount of calculation.The simulation results verify the effectiveness of the active power filter based on the improved SVPWM control strategy. |
