Abstract: Mine Hoist plays a vital role in the coal mine production, but with current harmonics at same time. This paper presents a new three-level NPC parallel active filter, which has a funtion of the DC hoist load harmonic compensation, while the limit on harmonic load does not meet the compensating device capacity, both reactive power compensation. The simulation studies have demonstrated the feasibility and benefits of secondary programs. For NPC three-level active filter key technologies are discussed. Propose a new voltage PLL technology, in the coal mine power grid transients and other environmental imbalances and still have an excellent lock capacity, improve system stability.

Key words: APF, PLL, NPC three level, Mine