Pre-research On Hybrid Cascaded Active Power Filter

Comparing with passive power filter, in terms of harmonic suppression of power system, active power filter has remarkable advantages of dynamic continuous real-time compensation.The research of low-voltage active power filter is comparatively mature, comparing with low-voltage APF, the research emphasis of high-voltage APF is not the method of harmonic and reactive current detection, but the topology and control algorithm, which needs to be improved.Aiming at the defects of can not possess high power and high frequency at the same time when suppressing high power system harmonic pollution., comparing with the topologies of the other high-voltage APF, this paper adopts a new hybrid cascaded multi-level topology, it can enhance output power and increase the switching frequency, so as the effect of compensation.This active power filter consists of two parts that can be equivalent to voltage source and current source, respectively, they are connected in series, the current source is constituted by PWM converter, and the extraction and tracking of harmonic and reactive current is achieved by DSP. The voltage source is constituted by three cascaded H-bridge converters, and the generation and calculation of 27-level voltage driving signal is achieved by FPGA, the fundamental component of its output voltage counteracts grid voltage, so the current source can work in the environment of low voltage, so it can increase the switching frequency of PWM converter, the compensation characteristic is better, the control strategy is simple and easy to implement.As the pre-research of high-voltage active power filter, an experiment platform of 220V/10kVA is built, MATLAB simulation and the experiment results show the availability and practicability of the topology.