SMALL SIGNAL PERTURBATION ANALYSIS FOR PARALLEL MICRO GRID INVERTERS

The paper orients to evolve a framework for ensuring the stable operation of the inverters connected in parallel within a Micro grid. It develops a model of the N parallel inverter system through the use of the state space averaging technique and introduces the theory of linearized perturbation technique to arrive at the equilibrium state around the chosen quiescent point. The system operates from a solar source and it has a SEPIC (Single Ended Primary Inductor Converter) which exploits the use of the maximum power and in turn support the parallel inverters. It engages the design of a linear quadratic regulator (LQR) controller in an effort to increase the power quality indices of the output voltage. It examines the performance using MATLAB based simulation from where it offers a regulated output voltage and a reduction in the total harmonic distortion (THD) and the harmonic spread factor (HSF) across the operating range. The experimental readings obtained from the prototype fabricated using AT Mega 8 processor serve to validate the simulation results and establish the suitability of the use of the system in real world applications. The frequency domain plot assuages the steady state stability and claims a space for its use in the stand alone utility grids.