Voltage harmonic control of weak utility grid through distributed energy systems

Abstract

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.

Improved weighted average current control of LCL grid‐connected inverter and analysis of its order reduction characteristics

“…The physical meanings of the parameters that appear in the diagram are listed in Table 1. It should be noted that there is an equivalent grid impedance Z g in the weak grid, in this study, we consider Z g only as inductance L g [21][22][23] in the most extreme situation.…”

An Enhanced Harmonic Voltage Compensator for General Loads in Stand-alone Distributed Generation Systems

“…However, the PI controller is unable to maintain a sinusoidal DG output voltage when unbalanced and/or nonlinear loads are connected to the PCC due to its limitation of the control bandwidth. In order to overcome this issue, several advanced control methods have been proposed such as PI controllers in [8], [9], predictive control [10], [11], adaptive control [12], multiple resonant controllers [13], [14], and repetitive control [15].…”

“…In [8], [9], to supply a pure sinusoidal output voltage at the PCC under a nonlinear load, a bank of PI controllers was used where each PI controller regulated the magnitude of a single harmonic voltage. In these control methods, many PI controllers and coordinate transformations are required to compensate all of the voltage harmonics, which makes this type of control strategy too complex.…”