BROG series active filter adopts three-level topological structure and applies advanced control algorithm, with high power density, high efficiency, low cost, low noise, and other apparent advantages. It can be used for multiple purposes, takes harmonic control as the main function, and is optical for reactive power compensation and three-phase unbalanced compensation functions. Single module can run independently with high reliability; the convenient capacity expansion, parallel connection and plug-in modular design can support expansion of different capacities, online capacity expansion and maintenance; in case of multiple compensation, the failure of one device does not affect the normal operation of other modules, and is of high reliability.