A Robust Frequency Control Technique for Wind Power Conversion with Two-Level Structure Predictive Method

Abstract

In modular and scalable matrix converters, which are deployed to interface the medium/high-power grids, there is huge interest to enhance the high computational burden of prevalent control schemes, such as model predictive control (MPC). In this paper, the operational performance of the Modular Multilevel Matrix Converter (M3C) is studied to transfer power generated by offshore wind farm and to interconnect the three-phase AC grid. The two-level structure control design is realized, of which a first-level predictive controller based on a Finite Control-Set Model Predictive Control (FCS-MPC) generates an initial controlled variables to regulate the converter branch voltages and currents. The second-level iterative controller is embedded into an integrated perturbation analysis and sequential quadratic programming (IPA-SQP) algorithm for handling uncertainty and updating weighting factors. The complete control scheme aiming to reduce sampling time and optimization of variable constraints, thus its optimality is proved through simulation analysis for a designed system with an equal or low operating frequency at the input or output AC systems for a M3C with 9-levelline-to-line voltage.