LLCL filtering-based active power filter compound control method

The invention discloses an LLCL filtering-based active power filter compound control method. Unstable pole locations of an LLCL filter are configured through inherent time delay of a digital system, so that non-damping resistance self-stabilized control of the LLCL filter is realized. The LLCL filter is connected with a power grid directly in specified configuration, so that total induction volume is reduced, system cost and harmonic wave output capability are decreased. Also, addition loss of traditional passive damping and that active damping needs external sensors or is affected by model precision are avoided. The compound control method is very suitable for being applied to large power inverters.