Research On Harmonic Detection Method Of Shunt Active Power Eilter

It is necessary for ideal power supply to ensure the sustained and rapiddevelopment of the national economy. But the power electronic devices are widely usedin recent years, lots of harmonic do harm to the power grid and result in more and moreelectric energy loss. To improve power quality, it must take corresponding measure toreduce harmonic content. APF is recognized as an effective means of harmonicsuppression. New topology and harmonic current detection method and control strategyis the key to restrain the harmonics. The paper focus on the harmonic current detectionmethod, as follows:Firstly, the APF’s topology is classified in the paper, and the basic structure,working principle and compensation characteristics of shunt active power filter has beenstudied in detail particularly.Secondly, the improved ip–iqmethod based on average theory is studied in the idealsteady state by contrast to the traditional ip–iqmethod based on instantaneous reactivepower theory. Simulation results show that the average method has the characteristics oflow delay and high detection accuracy. To aim at the inherent shortcoming of theaverage method in the transient state, the paper proposed a new filter structure whichcombined butterworth low pass filter and average filter, the simulation verified that theimproved method can reform the detection performance of the average method.Thirdly, the mathematical model of three-phase shunt active power filter isestablished, then analyzing the main parameters selection principle of the main circuit.The common current tracking control strategy of APF is described, and the HCC controlstrategy is selected. The reason of DC voltage fluctuation is described, using the PIcontrol strategy could stabilize the DC voltage.Finally, the paper build a APF system model which contain each functionalsub-module in the simulink platform. Then the system simulate in the steady state andtransient state combined harmonic current detection method with HCC and PI controlstrategy, the results furtherly verified that the two improved ip–iqmethod both own afine detection performance.