A 7.2 kV experimental setup of a third harmonic hybrid active filter for medium voltage utility applications

A practical third harmonic hybrid active filter capable of cost-effectively suppressing third harmonic currents in medium voltage distribution systems was proposed in [1]. The design of the proposed filter was driven by strict utility requirements - reliability, cost, and system impact. This paper extends the previous work by designing, building, and testing a 7.2 kV medium voltage experimental implementation of the proposed filter. Extensive simulations were performed to ensure safe operation of the experimental setup under normal operating conditions and during faults/shutdown of the filter. Experimental results are presented which demonstrate the performance of the proposed filter. The impact of a distributed filtering solution based on the proposed filter on a typical residential/small commercial distribution system was analyzed using actual utility data. The simulation results show considerable third harmonic neutral current and neutral-to-earth voltage reduction by deploying the proposed filter.