A New Control Strategy for Harmonic Mitigation Using Open UPQC in Modern LV Networks

The higher penetration of both renewable generation units and nonlinear loads is leading to higher levels of harmonics in microgrids and modern distribution systems. Accordingly, the operation of the sensitive loads in the grid can be affected by the low quality of the power delivered to the customers. Moreover, the higher harmonic levels lead to an increase in losses and lower energy efficiency in the grid. Hence, the harmonics in the grid are regarded as a great challenge by both the customers and Distribution System Operators (DSOs). Accordingly, the researchers have widely focused on minimizing the harmonics of the modern grids using Custom Power Devices (CPDs) in recently published papers. Among the devices incorporated in previous studies, the Open-UPQC is found as an effective and applicable solution for power quality improvement in microgrids and modern distribution systems which can provide benefits for both customers and DSOs. In this paper, a new coordination strategy is proposed for the Open-UPQC to provide the highest harmonic elimination capability besides the voltage improvement in the grid. In order to evaluate the effectiveness of the proposed method, the control strategy is applied to a sample modern distribution system which is formed by adding harmonic-injecting loads to a grid with real data. The results of simulations verified that applying the proposed control strategy to the Open-UPQC provides the effective harmonic reduction in the grid by using the improved coordination of the shunt units.