Design and operation of cascaded active power filters for the reduction of harmonic distortions in a power system

To solve the rated power problem of active power filters, more than one active power filter can be connected in cascade, where each of the active power filters operates at different switching frequencies and contains a different power rating. A novel control algorithm that is efficient for controlling these cascaded active power filters is proposed. In the proposed algorithm, only one reference current calculation circuit and four current sensors are required for the three-phase three-wired applications. Simulations have been made to compare the performance of the proposed algorithm with other control algorithms. The laboratory prototype that contains two three-phase three-wired active power filters was also completed. These test results have demonstrated the feasibility and practicality of the proposed method for the applications considered