Wave-to-grid (W2G) control of a wave energy converter

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...…”

“…To align the voltage outputs of power generators with the power grid, Voltage Source Converters (VSCs) must be connected to them [9][10][11][12]. Wave energy conversion utilizing Permanent Magnet Linear Synchronous Generators (PMLSGs) and AC/DC Voltage Source Converters (VSCs) enables efficient harnessing of wave energy and the generation of substantial electric power, which can be integrated into the electricity grid [13][14][15][16]. Controlling the motion of such a generator under waveinduced excitation is a non-trivial task that necessitates sophisticated nonlinear control algorithms [17][18][19][20].…”

Maximal electric power generation from varying ocean waves with RLC-tuned reactive PTO force

“…To reveal the fundamental M-E dynamics, we assume that the whole WEC system is linear, the water is homogeneous, inviscid, irrotational and incompressible and the waves are sinusoidal, so the waves are describable by potential-flow theory [1], [3]; the added mass corresponding to the radiation force is constant [17], [23]; the shaft is rigid and lossless, and hence the buoy and translator (BT) and its added fluid mass move together as a single mass and all the masses are lumped into the system total mass M m . These assumptions encapsulate the essential traits of WECs and are commonly employed in the analysis and design of WECs [24], [25].…”

“…where B m is the radiation damping constant due to the interaction of the buoy motion and surrounding water. The hydrostatic stiffness force f h (t) is described as [23], [28] f…”

“…1) When ω = ω 0 , disconnect C and L to make C = 0 and L = ∞ in ( 9) and hence M ei = 0 and K ei = 0 in (23). 2) When ω < ω 0 , disconnect L to make K ei = 0 and tune C to make (23). From ( 9), the C (in Farad, F) thus tuned is given by…”