Model Predictive Control-based Power take-off Control of an Oscillating Water Column Wave Energy Conversion System

Rajapakse, Gimara; Jayasinghe, Shantha Gamini; Fleming, Alan; Shahnia, Farhad

doi:10.1088/1755-1315/73/1/012010

Cited by 4 publications

(18 citation statements)

References 8 publications

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“…The active and reactive power of the generator output in the αβ reference frame, assuming a balanced three-phase system are given as [3,31]: …”

Section: Pmsg and Grid Modelmentioning

confidence: 99%

“…The space vector models of the three-phase source voltage ( → v ) and source current ( → i ) derived from the phase voltages (v sa , v sb , v sc ), and currents (i sa , i sb , i sc ) can be represented by [3,32]:…”

Section: Pmsg and Grid Modelmentioning

confidence: 99%

“…The mathematical model of the variable speed multi-pole permanent magnet synchronous generator (PMSG) in the dq synchronous rotating reference frame, assuming symmetrical stator windings, negligible stator slots' effect on the rotor inductances with rotor position, negligible magnetic hysteresis and saturation effects, and constant power losses in windings can be given by [3,[33][34][35]:…”

Section: Pmsg and Grid Modelmentioning

confidence: 99%

“…Wave energy is a vast, sustainable and low environmental impact renewable energy source which is gaining popularity among the research community [1][2][3][4]. Numerous studies have been conducted and various technologies have been developed to convert wave energy into electricity since mid-twentieth century [5].…”

Section: Introductionmentioning

confidence: 99%

“…Amidst the drawback of power pulses, WSE and other companies commissioning similar types of commercial scale projects believe that the OWC system will be reliable, require less maintenance and be cost effective compared to other onshore renewables and fossil fuels in coming years [3,6,7,10]. To achieve these objectives and promote WEC as a competitive renewable energy technology, it is essential to achieve the maximum overall efficiency from wave to wire and comply with the grid codes applicable to the WEC system.…”

Section: Introductionmentioning

confidence: 99%

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A Model Predictive Control-Based Power Converter System for Oscillating Water Column Wave Energy Converters

et al. 2017

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Abstract:Despite the predictability and availability at large scale, wave energy conversion (WEC) has still not become a mainstream renewable energy technology. One of the main reasons is the large variations in the extracted power which could lead to instabilities in the power grid. In addition, maintaining the speed of the turbine within optimal range under changing wave conditions is another control challenge, especially in oscillating water column (OWC) type WEC systems. As a solution to the first issue, this paper proposes the direct connection of a battery bank into the dc-link of the back-to-back power converter system, thereby smoothening the power delivered to the grid. For the second issue, model predictive controllers (MPCs) are developed for the rectifier and the inverter of the back-to-back converter system aiming to maintain the turbine speed within its optimum range. In addition, MPC controllers are designed to control the battery current as well, in both charging and discharging conditions. Operations of the proposed battery direct integration scheme and control solutions are verified through computer simulations. Simulation results show that the proposed integrated energy storage and control solutions are capable of delivering smooth power to the grid while maintaining the turbine speed within its optimum range under varying wave conditions. Keywords: active front end rectifier; finite control set-model predictive control (FCS-MPC); two-level voltage source inverter; wave energy conversion (WEC)

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“…The active and reactive power of the generator output in the αβ reference frame, assuming a balanced three-phase system are given as [3,31]: …”

Section: Pmsg and Grid Modelmentioning

confidence: 99%

Section: Pmsg and Grid Modelmentioning

confidence: 99%

Section: Pmsg and Grid Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Model Predictive Control-Based Power Converter System for Oscillating Water Column Wave Energy Converters

et al. 2017

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Grid Integration and Power Smoothing of an Oscillating Water Column Wave Energy Converter

et al. 2018

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This paper applies model predictive control (MPC) for the power processing of an oscillating water column (OWC) wave energy conversion (WEC) system to achieve smooth power delivery to the grid. The particular air turbine design adopted in this study produces large power pulses ranging from 0 to 1 MW in magnitude, and thus, direct connection to the grid is practically impossible, especially in weak grid conditions. Therefore, energy storage is an essential element that should be integrated into this particular WEC system in order to absorb power pulses and thereby ensure smooth delivery of power to the grid. Taking into account the repetitive nature, duration, and magnitude of the power pulses, this study has chosen "supercapacitor" as the suitable energy storage technology. The supercapacitor energy storage (SCES) is integrated into the dc-link of the back-to-back power converter of the WEC system through a bidirectional dc-dc converter. In order to achieve the desired operation of this complex power converter arrangement, a finite control set MPC strategy is proposed in this paper. Performance of the proposed energy storage system (ESS) and control strategy are evaluated through computer simulations. Simulation results show that the proposed SCES system and the control strategy are able to achieve smooth power delivery to the grid amidst power pulses coming from the generator. exhale and inhale air streams through the open end of the chamber. Energy of the air stream is then converted into electricity with the aid of a turbine coupled generator. The commonly used turbines are bidirectional which extract energy from both the inhale and exhale streams.The Australian maritime college, in collaboration with the Wave Swell Energy Ltd., has developed a new OWC air turbine technology, which has been recognized as an efficient and simple design compared with many other OWC technologies [6,7]. This particular configuration has passive, non-return air flow valves built into its chamber, which activate during the exhale stage and equalize the pressure inside the chamber to the atmosphere, which allows the rising water column to reach its maximum height. This creates a higher differential pressure during the inhale stage resulting in high velocity air stream through the turbine. Since this particular air turbine extracts energy only during the inhale stage, the output power inherently becomes discrete pulses. These large and discrete power pulses create major operational issues, such as frequency deviations, voltage sags/swells, and instabilities if delivered to the grid without smoothing. Therefore, energy storage is an essential feature that should be incorporated into the power converter of the WEC system. Nevertheless, in contrast to wind energy or tidal energy turbines, where the rotational speed should be changed according to the wind speed or tidal flow speed, the unidirectional air-turbine used in this study does not necessarily require variable speed operation. Therefore, according to [8], the turbine speed can be ...

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Numerical Simulation Method of Hydraulic Power Take-Off of Point-Absorbing Wave Energy Device Based on Simulink

Jing,

Wang,

Sant

et al. 2024

Energies

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Wave energy has a high energy density and strong predictability, presenting encouraging prospects for development. So far, there are dozens of different wave energy devices (WECs), but the mechanism that ultimately converts wave energy into electrical energy in these devices has always been the focus of research by scholars from various countries. The energy conversion mechanism in wave energy devices is called PTO (power take-off). According to different working principles, PTOs can be classified into the linear motor type, hydraulic type, and mechanical type. Hydraulic PTOs are characterized by their high efficiency, low cost, and simple installation. They are widely used in the energy conversion links of various wave energy devices. However, apart from experimental methods, there is currently almost no concise numerical method to predict and evaluate the power generation performance of hydraulic PTO. Therefore, based on the working principle of hydraulic PTO, this paper proposes a numerical method to simulate the performance of a hydraulic PTO using MATLAB(2018b) Simulink®. Using a point-absorption wave energy device as a carrier, a float hydraulic system power-generation numerical model is built. The method is validated by comparison with previous experimental results. The predicted power generation and conversion efficiency of the point-absorption wave energy device under different regular and irregular wave conditions are compared. Key factors affecting the power generation performance of the device were investigated, providing insight for the subsequent optimal design of the device, which is of great significance to the development and utilization of wave energy resources.

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Model Predictive Control-based Power take-off Control of an Oscillating Water Column Wave Energy Conversion System

Cited by 4 publications

References 8 publications

A Model Predictive Control-Based Power Converter System for Oscillating Water Column Wave Energy Converters

A Model Predictive Control-Based Power Converter System for Oscillating Water Column Wave Energy Converters

Grid Integration and Power Smoothing of an Oscillating Water Column Wave Energy Converter

Numerical Simulation Method of Hydraulic Power Take-Off of Point-Absorbing Wave Energy Device Based on Simulink

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