Centralised model-predictive decoupled active–reactive power control for three-level neutral point clamped photovoltaic inverter with preference selective index-based objective prioritisation

• Published in: IET power electronics Vol. 12; no. 4; pp. 840 - 851
• Main Authors: Bonala, Anil Kumar, Sandepudi, Srinivasa Rao
• Format: Journal Article
• Language: English
• Published: The Institution of Engineering and Technology 10.04.2019
• Subjects: active–reactive power tracking; centralised model predictive control; centralised model‐predictive; classical proportional–integral‐based model predictive control; CMPC; control approach; control objectives; DC‐link capacitor voltage balancing; DC‐link voltage control loop; DC‐link voltage regulation; decoupled active‐reactive power control; dynamic tracking performance; electric current control; invertors; maximum power extraction; optimal control; optimal control action; photovoltaic inverter; photovoltaic power systems; PI control; power grids; predictive control; preference selective index‐based dynamic weighting factor selection approach; preference selective index‐based objective prioritisation; reactive power control; reactive power exchange; Research Article; single objective function; single‐stage grid‐tied three‐level; steady‐state; three‐level neutral point; voltage control; CMPC; optimal control action; electric current control; classical proportional–integral-based model predictive control; DC-link capacitor voltage balancing; invertors; reactive power exchange; dynamic tracking performance; single objective function; active–reactive power tracking; control objectives; power grids; DC-link voltage control loop; maximum power extraction; control approach; PI control; steady-state; photovoltaic power systems; decoupled active-reactive power control; centralised model-predictive; optimal control; photovoltaic inverter; DC-link voltage regulation; preference selective index-based objective prioritisation; reactive power control; centralised model predictive control; predictive control; single-stage grid-tied three-level; three-level neutral point; preference selective index-based dynamic weighting factor selection approach; voltage control
• ISSN: 1755-4535; 1755-4543
• DOI: 10.1049/iet-pel.2018.5825

This study presents a single-stage grid-tied three-level neutral point clamped photovoltaic inverter with a centralised model-predictive decoupled active–reactive power control. The proposed centralised model predictive control (CMPC) incorporates the constraints of maximum power extraction, dc-link capacitor voltage balancing and active–reactive power tracking in a single objective function. The dc-link voltage of the inverter is regulated to its reference for extracting the maximum power. In order to eliminate the impact of reactive power exchange on floating dc-link voltage regulation, a decoupled active–reactive power control is used in the CMPC. Furthermore, a preference selective index-based dynamic weighting factor selection approach is introduced to maintain the relative importance between the power tracking and dc-link capacitor voltage balancing. The proposed control approach eliminates the outer dc-link voltage control loop and also, the empirical approach required for the selection of weighting factors. As a result, it ensures an optimal control action in each sampling period to improve the steady-state and dynamic tracking performance of the control objectives. The proposed control approach is experimentally verified by using a 1.2 kW laboratory-scale prototype and the results are presented to demonstrate its effectiveness compared to the classical proportional–integral-based model predictive control.