An efficient procedure to design passive LCL-filters for active power filters

Variable high switching frequencies in grid-connected active power filters could lead to low harmonic performance and expose power systems to EMI issues too. A low-pass passive LCL-filter is usually used to interconnect a power electronic converter to a grid system. (This can also be done by using a passive L-filter.) Nevertheless, designing an LCL-filter is not simple because of high compensating bandwidth and variable frequency modulations involved in active filters. This paper examines various effective conditions on designing this kind of passive LCL-filters. Then it will propose a comprehensive design procedure in which both the outcomes of the active filter and the network obligations are taken into account. Principal advantages of this proposal are reduction of power losses of the passive filter, lowering the converter’s switching ratings and the simplicity of the suggested design algorithm. A typical grid-connected shunt active filter is considered, and the needed interconnecting LCL-filter is designed using the proposed method. Then, the whole system is simulated with SIMULINK to verify the discussed procedure. Simulations confirm substantial reduction in power losses and converter current ratings.