Voltage harmonic control of weak utility grid through distributed energy systems

This paper proposes a closed loop control method to reduce the voltage harmonics of the weak utility grid through distributed energy systems (DES). It is desired to have uniform voltage and frequency around grid. The grid voltage gets distorted due to the nonlinear behavior of the distributed loads and sources. It is possible to correct the distorted utility grid locally at the point of connection with the DES. The proposed method adds to the responsibility of the DES in estimating the grid voltage harmonics and injecting additional current to rectify the grid voltage pollution. Recursive Least Squares Estimation (RLSE) technique has been implemented to estimate the grid voltage harmonics, which works harmoniously with closed loop harmonic voltage controller. DES with the proposed control technique reduces the voltage harmonic in addition to providing the sustainable energy to the utility grid. The results are verified with the simulation and experimental tests on a 5 kW utility interactive energy conversion system.