Hybrid series active, parallel passive, power line conditioner for harmonic isolation between a supply and a load

A power line conditioner, comprising:

• an active filter connected in series to a power distribution network, said power distribution network including a voltage source and a load, said voltage source inducing unbalanced supply currents in said power distribution network;
• a passive filter coupled, in parallel, to said power distribution network;
• and
• an active filter controller coupled to said active filter and said power distribution network, said active filter controller including
• means for identifying a negative sequence fundamental component signal and a positive sequence fundamental component signal in said unbalanced supply currents,
• means for adding said negative sequence fundamental component signal and said positive sequence fundamental component signal to form an active filter reference signal, and
• means for applying said active filter reference signal to said active filter, causing said active filter to operate as a harmonic isolator between said voltage source and said load.

A method of operating a power line conditioner of the type including an active filter connected to a power distribution network, and an active filter controller connected to said active filter and said power distribution network, said power distribution network including a voltage source inducing an input current at a first end of said power distribution network and a load at a second end of said power distribution network, said input current having unbalanced components, said method comprising the steps of:

• identifying a positive sequence fundamental signal within said input current;
• distinguishing a negative sequence fundamental signal within said input current;
• combining said positive sequence fundamental signal and said negative sequence fundamental signal to form an inverter reference signal;
• and
• applying said inverter reference signal to said active filter to harmonically isolate said active filter from said voltage source.