Cascaded control for LCL filter based grid‐tied system with reduced sensors

Abstract

This work implements a cascaded control for the LCL filter-based grid-connected neutral point clamped (NPC) inverter with the reduced sensor. The conventional three-loop control requires two current sensors for the inverter side, two voltage sensors for the voltage side, and two current sensors for the grid side in total for sensing. This work proposes a novel cascaded control scheme that allows a considerable reduction of grid-side current sensors and capacitor-side voltage sensors. Only two inverter-side current sensors are required for the same. The sensing point is implemented by the proposed estimation algorithm. As an outcome, the hardware complexity, weight, size, and implementation cost of the system are downsized. A comparative assessment is performed between the conventional technique and the proposed methodology. The system is analysed for grid inductance and LCL filter parametric variations in order to assure the robustness and stability of the system. In addition, the system is also investigated for the influence of digital control delay. The implemented system offers enhanced system stability and improved dynamic performance. In order to meet grid regulation, it offers an economical solution. The proposed system is justified by simulated results on the MATLAB/Simulink platform and verified by the experimental results.