Design of a New LCL-LCL Harmonic Filter for High Attenuation in PV Array System

The use of Distributed or Disperse Generation is rapidly increasing in the modern distribution networks because of their potential advantages. They need DC/AC converter in order to interface to the grid .These type of active rectifiers/inverters are used more frequently in regenerative systems and distributed power systems. The switching frequency of these converters is generally between 5 kHz to 20 kHz and causes high order harmonics that can disturb other EMI sensitive loads/equipment on the grid side. Choosing a high value for the line-side inductance can solve this problem, the main goal is to ensure a reduction of the switching frequency ripple at a reasonable cost and, at the same time, to obtain a high performance active rectifier. As a drawback these LCL filters have very high gain at the filter cut-off frequency. As a result system becomes highly sensitive to outside disturbances. One way of reducing the resonance oscillation in current & voltage of the system is by adding a passive damping circuit to the filter. In which LCL-LCL filter which has high frequency and high attenuation than previous and better response at high frequency.