Predictive Power Control of PMSG based WECS: Development and Implementation for Smooth Grid Synchronisation, Balanced and Unbalanced Grid

In this paper, the distributed generation unit is controlled to operate in both stand-alone (SA) and grid-connected (GC) modes and offers a smooth transition between these modes using the model predictive control scheme. The permanent magnet synchronous generator (PMSG), along with a 2-level back-to-back converter, is named a DGU. A simple and intuitive approach using predictive control is presented in a stationary reference frame for a load-side converter (LSC). A voltage control loop is used during SA mode to fix the voltage and frequency at the load end. The smooth synchronization technique is developed without a phase-locked loop. During GC, a predictive power control regulates active and reactive power during the symmetry and unbalanced grid voltage conditions. The designed strategy makes the power factor improvement, reduction of grid current harmonics, and elimination of twice grid frequency ripple from power during grid unbalance possible. This work has proposed a solution to reduce the overall computational burden on the processor by eliminating the state prediction in each sampling period. The machine-end converter control is formulated in the rotor flux reference frame to keep the power flow across the dc-link capacitor constant. Comprehensive experiments are conducted with the designed scaled laboratory prototype to successfully validate the control's theoretical claim. & COPY; 2023 International Association for Mathematics and Computers in Simulation (IMACS). Published by Elsevier B.V. All rights reserved.

Automated summary

This paper presents a control scheme for distributed generation units to operate in stand-alone and grid-connected modes, with a smooth transition between the two. The control strategy includes predictive control for voltage and frequency regulation in stand-alone mode, and power control for symmetrical and unbalanced grid voltage conditions in grid-connected mode. The proposed control method improves power factor, reduces grid current harmonics, and eliminates grid frequency ripple.