CNISOGI and VSSMCLMS Filters for Solving Grid and Load Abnormalities for a Microgrid With Seamless Mode Transfer Capability

A cascaded non-identical second-order generalized integrator (CNISOGI) and a variable step size modified clipped least mean square (VSSMCLMS) adaptive filter are proposed for a microgrid to solve the grid and load abnormalities. The CNISOGI filter estimates the positive sequence components (PSCs) from polluted (unbalanced/distorted) grid voltages. Hence improved quality grid currents are realized even though the grid voltages are polluted. Moreover, the CNISOGI filter estimates the accurate phase angle and frequency of voltages; thus, seamless transition of the microgrid is achieved between different modes. The comparative performance of the CNISOGI filter is studied over different control techniques and it demonstrates the better filtering capability of the proposed control. The microgrid is connected to the grid or a diesel generator (DG) set in subject to the availability of energy sources and the load demand to supply uninterrupted electricity to loads. Therefore, it provides an attractive solution for powering critical loads. The load compensation is achieved with the help of a VSSMCLMS filter. It estimates the active fundamental component of the load currents with faster response and lesser weight oscillations. The comparative performance of the VSSMCLMS filter is studied over conventional filters in MATLAB/Simulink and under laboratory conditions to ascertain its superiority in the filtering process.