Research On Current-source Active Power Filter And Its Control Methods

With the continuous advancement and development of science and technology,non-linear high-power loads have been increasing,and the reactive power and harmonic pollution problems brought about by it have become more and more serious.Therefore,the management of harmonics and reactive power has become an important issue in improving power quality.Active power filter(APF)is a common harmonic control device,which can filter out harmonics and compensate reactive power in the system.At present,the commonly used APF mainly adopts the voltage-type inverter structure.In comparison,the current-type inverter has the advantages of fast response,high reliability,and wide filtering range,especially with the development of conductive materials and its energy storage technologies,current-type APF presents a good application prospect.In this paper,based on the analysis of APF working principle and its mathematical model,the harmonic current detection algorithm based on instantaneous reactive power theory is studied,and the test results are verified by simulation.APF based on traditional PI indirect control and direct control were analyzed.At the same time,by analyzing the topology of the current-mode APF,a corresponding mathematical model is established.And based on the principle of space vector control,the SVPWM control principle and implementation process of the current-mode inverter are studied.Sliding mode variable structure control has advantages of response speed and robustness.In this paper,based on the structural characteristics of the current type APF,the system control strategy based on sliding mode variable structure is studied.In the control,the sliding mode control method using the power-reaching law.And by adjusting the parameters,the approaching process to the sliding surface is accelerated and chattering is reduced.Using PSCAD/EMTDC software to build current-type APF simulation model,and the sliding-mode variable structure control strategy for the current-type APF based on the power-reaching law proposed in this paper was simulated and analyzed.And the simulation results show that the control method has good active filter and reactive power compensation effects,and can effectively compensate for asymmetric loads.