Control System And Software Design Of Power Electronics Filter

In modem electric power systems, due to the use of large scales of non-linear loads, the impact caused by harmonics and reactive power is becoming an increasingly serious problem. Power electronics filter can suppress harmonics and compensate reactive power, with fast response and a good dynamic compensation effect. Therefore, power electronics filter has become a hotspot in power electronics researching because of its superior compensation performance.First of all, the parallel power electronics filter can be divided into two types-with or without harmonic detection. Then, this paper explains the function of power electronics filter with harmonic detection and briefly analyses its advantages also the facing problems, which leads to the method and principle of power electronic filter without harmonic detection.Secondly, this paper particularly introduces the key technologies involved in the design of power electronics filter and their principle, including phase-locked loop, SVPWM and PI control. This paper has analyzed the model of phase-locked loop and made certain improvements in PLL by designing the parameters of low-pass filter within phase-locked loop, making the phase-locked characteristics better. On considering the feature of power electronic filter, that is its input and output signals are AC signals, this paper introduces PR control in current loop so that it can make comparison between PR and PI control over the control effect. The following is parameter design of dual closed-loop controllers towards single and three phase power electronic filters. After that, this paper use MATLAB simulation to verify the effectiveness of the controllers designed.Then, this paper carries out software programming for single and three phase power electronic filters. The whole programming is separated and packaged into several software modules. This programming method not only facilitates program transplantation, also is easier to update and maintain during the future. Furthermore, false warning is also added into the software programming for the sake of protecting devices.Finally, according to the specifications, this paper has built a hardware platform in order to test the validity of single and three phase power electronics filter designed above. In accordance with the characteristics of non-linear loads, the experiments will be divided into two groups-inductive and capacitive. The results show that power electronics filter designed has good control effects over response speed, stability and following performance. And no matter what the characteristic of non-linear loads is, power electronics filter has a good capability to eliminate harmonics. Therefore, it can efficiently improve the grid’s power factor.