Study On The Design And Parallel Strategy Of Active Power Filter

With the rapid development of China’s industrialization, nonlinear loads are widely applied to the power grid, which produce a lot of reactive and harmonic current caused serious pollution to the power grid. Active power filter(APF), as a kind of power electronic device which effectively suppress harmonic and compensate reactive power, has attracted more and more attention. Though the compensation rate of single APF is high, the capacity of single APF is small. In order to increase the capacity of parallel system, the Current research trend is to connect multiple APF as a system.However, the traditional strategy of shunt active power filter control system does not consider the power loss and service life of the parallel system. In the condition of smaller harmonic current, the APFs in the parallel system may run in no load or small load condition, this will cause a lot of meaningless power and life losses. Therefore, exploring an effective multi APF parallel strategy, to make the life loss of the whole system minimum at the same time, is a very meaningful direction.This paper based on the study of the single active power filter, puts forward a kind of multi APF parallel strategy, solve the problem of power and life losses of multi APF parallel system.First, this paper describes the basic working principle and control system of active power filter, introduces the hardware and software design scheme of three level I type APF, develops a prototype of 100 A three level active power filter.Secondly, compares the common APF parallel control strategy, analyzing the advantages and disadvantages of different strategies. Put forward a new kind of APF parallel control strategy, which not only ensures the compensation performance but also minimize the parallel system power loss and make each APF has the same running time though the optimization. This paper models the APF parallel system in the MATLAB environment, the speed and reliability of the parallel system in dynamic load and hot plug state is simulated and the experimental results proved the reliability of the parallel system.At last, Uses YALMIP toolbox to establish power and service life losses simulation model based on the actual test of single APF. The simulation model uses the harmonic of electric arc furnace of steelmaking plant as a harmonic source. The simulation results show that the parallel strategy can effectively reduce the power loss and the operation time of parallel system and proves the validity of this parallel strategy...