Optimal Control of Wave Energy Converters

Zou, Shangyan

doi:10.37099/mtu.dc.etdr/702

Cited by 6 publications

(23 citation statements)

References 93 publications

(116 reference statements)

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“…A comparison is drawn between this study and Ref. [17] for cases 1 and 2. Since case 3 uses the fitted non-periodic function, no comparison is made with Ref.…”

Section: Casementioning

confidence: 94%

“…These cases are selected to represent a range of possible scenarios for the WEC problem and allow us to compare the results with those reported in Ref. [17]. For the WEC problem m is 2×10 5 kg, k is 1.2×10 5 kg/s 2 , and c is 10 5 kgm 2 /s 3 .…”

Section: Wave Energy Converter Problem Formulation and Solution Processmentioning

confidence: 99%

“…Since case 3 uses the fitted non-periodic function, no comparison is made with Ref. [17], which uses non-periodic data from real experiments. In addition, brute-force application of methods that use variants of direct optimization methods fails for problems with singular control arcs unless remedial actions are taken.…”

Section: Casementioning

confidence: 99%

See 2 more Smart Citations

Optimal Control of Wave Energy Converters Using Epsilon-Trig Regularization Method

Mall,

Taheri

2019

Preprint

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The wave energy converter (WEC) devices provide access to a renewable energy source. Developing control strategies to harvest maximum wave energy requires solving a constrained optimal control problem. It is shown that singular control arcs may constitute part (or the entire) of extremal trajectories. Characterizing the optimal control structure, especially with the possibility of many switches between regular and singular control arcs, is challenging due to lack of a priori information about: 1) optimal sequence as well as number of the regular and singular control arcs, and 2) the corresponding optimal switch times (from a regular to a singular arc and vice versa). This investigation demonstrates the application of a recently developed construct, the Epsilon-Trig Regularization Method (ETRM), to the problem of maximizing energy harvesting for a point-absorber WEC model in the presence of control constraints. Utility of the ETRM for the WEC problem is demonstrated by comparing its high-quality results against those in the literature for a number of test cases.

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“…A comparison is drawn between this study and Ref. [17] for cases 1 and 2. Since case 3 uses the fitted non-periodic function, no comparison is made with Ref.…”

Section: Casementioning

confidence: 94%

Section: Wave Energy Converter Problem Formulation and Solution Processmentioning

confidence: 99%

See 1 more Smart Citation

Optimal Control of Wave Energy Converters Using Epsilon-Trig Regularization Method

Mall,

Taheri

2019

Preprint

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show abstract

“…Inserting ( 25) into ( 22) and replacing 𝑢𝑢 𝑑𝑑 (𝑠𝑠) by ( 27) yields a first-order closed loop transfer function for the daxis in (29). The PI compensator𝑐𝑐 𝑝𝑝 (𝑠𝑠) is defined in (34) for d-axis compensation.…”

Section: 𝐺𝐺(𝑠𝑠) =mentioning

confidence: 99%

“…The energy absorption of a WEC in regular and irregular waves can be influenced by a declutching control in [29]. A study about constrained and unconstrained optimal control of a heaving pointabsorber was investigated in [30].…”

Section: Introductionmentioning

confidence: 99%

Comparative Analysis of Linear and Nonlinear Control of Wave Energy Converter for a Force Control Application

et al. 2020

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The aim of wave energy converters (WECs) is to harvest the energy from the ocean waves and convert into electricity. Optimizing the generator output is a vital point of research. A WEC behaves as a nonlinear system in real ocean waves and a control that approximates the behaviour of the system is required. In order to predict the behaviour of WEC, a controller is implemented with an aim to track the referenced trajectory for a force control application of the WEC. A neural model is implemented for the system identification and control of the nonlinear process with a neural nonlinear autoregressive moving average exogenous (NARMAX) model. The neural model updates the weights to reduce the error by using the Levenberg-Marquardt back-propagation algorithm for a single-input-single-output (SISO) nonlinear system. The performance of the system under the proposed scheme is compared to the same system under a PI-controller scheme, where the PI gains have been tuned accordingly, to verify the control capacity of the proposed controller. The results show a good tracking of dq (direct-quadrature) axes currents by regulating the stator currents, and hence a force control is achieved at different positions of the translator. The dynamic performance of the control is verified in a time domain analysis for the displacement of the translator.

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Power maximising control of a heaving point absorber wave energy converter

Ding

Sergiienko

et al. 2021

IET Renewable Power Gen

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Control systems play a critical role in improving the economic viability of wave energy converters (WEC). This paper presents a framework for a causal power-maximising feedback controller inspired by Phi method. Quadratic damper control and PID control are combined to collectively achieve the optimal power absorption conditions for the peak wave periods, which results in a nonlinear controller being suboptimal in irregular waves. The proposed controller is tested on a fully submerged heaving spherical point absorber in regular and irregular wave conditions in time domain. The tuning of the PID gains are investigated in frequency-domain from a stability and control bandwidth perspective. The modelled WEC dynamics includes linear hydrodynamic forces (excitation and radiation) and the nonlinear viscous drag force. The main benefits of the proposed controller are (i) it does not require any time-consuming optimisation either online or offline; (ii) has a wider bandwidth and better power absorption performance as compared to the conventional spring-damper (PI) controller; and (iii) easy to implement in practice like standard PID control.

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Optimal Control of Wave Energy Converters

Cited by 6 publications

References 93 publications

Optimal Control of Wave Energy Converters Using Epsilon-Trig Regularization Method

Optimal Control of Wave Energy Converters Using Epsilon-Trig Regularization Method

Comparative Analysis of Linear and Nonlinear Control of Wave Energy Converter for a Force Control Application

Power maximising control of a heaving point absorber wave energy converter

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