Algorithm Research Of Reactive And Harmonic Current Detection Under The Complex Power Grid

New structural components and materials have been found constantly in recent years and widely used in various industries,which bringing a big development in the power electronic technology.Because the large number of power electronic devices connected to the power grid, a lot of harmonics have been produced to pollute the electricity net. At the same time producing a certain reactive power, which cannot make the power grid to operate safe effective and stable. Active power filter is a kind of current compensation device, which can reduce the impact of harmonics and reactive currents on the power grid by compensating a certain amount of electric current. Because the device has good real-time performance and good dynamic performance, it has been widely used.The classification, working principle and mathematical model of active power filter are explained in detail in this paper. This paper focuses on the application of parallel active power filter. The p-q and ip-iq current detection method can accurately detect the harmonic and reactive currents, but it will generate large error under the condition of non ideal power grid. According to the ip-iq current detection theory, a current detecting method of the positive and negative sequence decoupling network based on the complex filtering was proposed. Theoretical analysis and simulation results show that the proposed method not only has simple structure, good real-time performance and high detection accuracy, but also can adapt to the complex environment of power grid.Finally, based on the improved ip-iq current detection algorithm, This paper design a set of hardware circuit which take the TMS320F2812 as the control core,Hardware circuit design includes the main circuit design and control circuit design. The control circuit includes three-phase voltage and current acquisition and conditioning circuit, DC side capacitor voltage acquisition and regulating circuit,power supply circuit, the adjustment of the IGBT drive circuit, PWM signal generating circuit. This paper builds a mathematical modeling of APF compensation system by the simulation tool of matlab, first of all, A simulation is done to thecurrent detection algorithm before and after improvement in the case of three kinds of different power grid. The accuracy of the improved algorithm is verified by Fundamental distortion rate. Then using the Improved algorithm to simulating the whole APF compensation system. Simulation results show that the feasibility and effectiveness of the proposed APF compensation system.