An Enhanced Grid Current Compensation Technique for Distributed Generation Systems

This paper has proposed an intelligent current control strategy for the grid-connected DG to simultaneously eliminate the effect of grid voltage distortion and nonlinear local load on the grid current. The simulation results established that the DG with the proposed current controller can sufficiently transfer a sinusoidal current to the utility grid, despite the nonlinear local load and distorted grid voltage conditions. The proposed current control scheme can be implemented without the local load current sensor and harmonic analysis of the grid voltage; therefore, it can be easily integrated in the conventional control scheme without installation of extra hardware. Despite the reduced number of current sensors, the quality of the grid current is significantly improved: the THD value of the grid current is decreased considerably compared with that achieved by using the conventional current controller like PI. In addition, the proposed current controller also maintained a good quality of grid current under grid frequency variations and total harmonic distortion (THD) decreases. Moreover, the dynamic response of the grid current controller with fuzzy logic was also greatly enhanced compared with that of the traditional PI-RC topology.

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