Non-linear coordinated control of LPMG-based direct drive wave energy conversion system with supplementary energy storage system based on feedback linearization

Abstract

The linear permanent magnet generator (LPMG)-based direct drive wave energy conversion system (DDWECS) works under perpetual fluctuations of ocean waves. Short-term energy storage, such as electrochemical energy storage, is usually adopted in a supplementary energy storage system (SESS) to buffer power fluctuations. Since the investigated DDWECS consists of various non-linear components such as insulated gate bipolar transistors (IGBTs)-based power electronic converters, the unremitting changes of system working conditions caused by ocean wave effects will degrade the dynamic performance with conventional linear controllers which are implemented via local linearization around a single working condition. This paper proposes the multiple feedback linearization based non-linear coordinated control (MFLNCC) scheme for coordinating non-linear plants in DDWECS with SESS such as the machine-side converter (MSC), the grid-side converter (GSC) and DC/DC converter in SESS. The enhanced dynamic performance of the proposed MFLNCC in DDWECS with SESS is validated under different scenarios.