High‐performance control for a permanent‐magnet linear synchronous generator using state feedback control scheme plus grey wolf optimisation

Abstract

This study proposes an optimal control scheme for a permanent-magnet linear synchronous generator (PMLSG) using the state feedback control (SFC) method plus the grey wolf optimisation (GWO) algorithm. First, A novel state-space model of linear PMLSG is established in order to obtain desired dynamics and enough power when used for the smooth wave energy. Second, the GWO algorithm is adopted to acquire weighting matrices Q and R in the process of optimising linear quadratic regulator (LQR). What is more, a penalty term is brought into the fitness index to reduce the overstrike of output voltage and keep the rate of work more stable. Finally, optimal LQR-based SFC with and without penalty term and proportionalintegral (PI) controllers are compared both in simulations and in experiments. Results clearly prove that the proposed optimal control strategy performs a better response when compared to other strategies.

Nonlinear Optimal Control for a PMLSG-VSC Wave Energy Conversion Unit

“…Overview of research results on control and optimization of WECS. [1][2][3][4] WECS consists of multi-phase AC generators and voltage source converters [5][6][7][8] Use of AC generators in connection to VSCs for wave energy conversion [9][10][11][12] Models and operation principles of generators and converters in WECS [13][14][15][16] Performance of wave-to-grid configurations of wave energy conversion units [17][18][19][20] Approaches to optimal control and optimized configuration of WECS [21][22][23] Control of converters for synchronizing WECS with the electricity grid [24][25][26][27] Control of power generation and power storage in wave energy conversion [28][29][30][31][32] Control for ensuring uninterrupted and maximized power supply from WECS [33][34][35][36][37] Modeling and control for optimizing power generation from WECS [38][39][40] New methods for nonlinear control of renewable energy systems and WECS The motion of the moving part (mover) of the PMSLG is given by: 𝑀𝑧̈= −𝑏 𝑔 𝑧̇− 𝑏 𝜔 𝑧̇− 𝑘 𝑠 𝑧 + 𝐹 𝑒 + 𝐹 𝑏𝑟 (1) where 𝑏 𝑔 𝑧̇ is the friction force that resists the motion of the moving part of the tubular PMLSG, 𝑏 𝑤...…”

“…Additionally, control of the integrated wave power generation systems, which comprise PMLSGs serially connected to VSCs, is a subtle task that should compensate for the complicated nonlinear dynamics and multivariable structure of these energy conversion units [24][25][26][27]. Among recent results in PMLSG and VSC-based wave power conversion systems, one can distinguish methods for maximizing the amount of wave power finally converted to exploitable electric power [28][29][30][31][32]. Several other results exist on the stabilization of WECs and on the VSC-based integration of these power units to the electricity grid [33][34][35][36][37].…”