Henk Polinder

Delft University of Technology | TU · Department of Maritime and Transport Technology (M&TT)

Wave-to-Wire models play an important role in the development of wave energy converters. They could provide insight into the complete operating process of wave energy converters, from the power absorption stage to the power conversion stage. In order to cover a set of relevant nonlinear effects, wave-to-wire models are predominately established in...

An adjustable draft point absorber was recently proposed as a novel approach to improve power absorption with constrained power takeoff (PTO) capacities. The key feature of the novel wave energy converter (WEC) concept is to adjust the buoy draft by regulating the ballast water inside the buoy, which aims to enable variation of the natural frequenc...

This paper presents a comprehensive literature review of the state-of-the art modeling and optimization methods for the power and propulsion systems of ships. Modeling is a tool to investigate the performance of actual systems by running simulations in the virtual world. There are two main approaches in modeling: physics-based and data-driven, whic...

This article gives an overview of challenges in primary distribution, protections and power scalability for shipboard DC systems. Given that DC technology is in development, several aspects of shipboard systems have not yet been sufficiently devised to ensure the protection and efficiency demanded. Several issues in DC systems arise from the lack o...

A crucial part of wave energy converters (WECs) is the power take-off (PTO) mechanism, and PTO sizing has been shown to have a considerable impact on the levelized cost of energy (LCOE). However, as a dominating type of PTO system in WECs, previous research pertinent to PTO sizing did not take modeling and optimization of the linear permanent magne...

The current focus of offshore wind industry and academia lies on regions with strong winds, neglecting areas with mild resources. Photovoltaic’s cost reduction has shown that even mild resources can be harnessed economically, especially where electricity prices are high. Here we study the technical and economic potential of offshore wind power in I...

A spectral domain model is established to analyze the performance of a recently proposed wave energy concept, namely the adjustable draft point absorber. The non-linear hydrostatic force is incorporated in the spectral domain model. To improve the accuracy of the proposed model, the incident wave elevation is considered in the statistic linearizati...

The Power TakeOff (PTO) rating of Wave Energy Converters (WECs) is generally much higher than the average extracted power. Scientific literature has indicated that downsizing the PTO capacity to a suitable level is beneficial for improving the techno-economic competitiveness. In this paper, a novel design, namely the adjustable draft system, is pro...

The significant increase in rotor diameters seen in modern wind turbines has pushed gearbox manufacturers to introduce technological innovations to increase the torque density of current designs. Driven by the need to lower the cost of energy from wind and size limitations imposed by logistic constraints in onshore wind, a trend has emerged to incr...

Accurate knowledge of the input torque in wind turbine gearboxes is key to improving their reliability. Traditionally, rotor torque is measured using strain gauges bonded to the shaft. Transferring the resulting signal from the rotating shaft to a stationary data acquisition system while powering the sensing devices is complex and costly. The magni...

The power take-off (PTO) system is a main component in wave energy converters (WECs), and it accounts for a notable proportion in the total cost. Sizing the PTO capacity has been proven to be significant to the cost-effectiveness of WECs. In the numerical modeling, the PTO size is normally represented by a force constraint. Therefore, to accurately...

This paper presents the state-of-the-art technologies and development trends of wind turbine drivetrains – the system that converts kinetic energy of the wind to electrical energy – in different stages of their life cycle: design, manufacturing, installation, operation, lifetime extension, decommissioning and recycling. Offshore development and dig...

Ships can avoid to be detected by magnetic mines by reducing their magnetic signature with degaussing coils. Degaussing currents are provided by switched mode power supplies which impose a current ripple on top of the degaussing current. The ripple might be visible in the magnetic signature which would increase the detectability of the ship. A way...

Detection of the magnetic signature of ships can be avoided by using a degaussing system; a set of on-board copper coils that compensates for the magnetic signature. High temperature superconductors (HTS) are currently investigated as a replacement for copper degaussing coils. By using HTS, we have to deal with higher currents and therefore with hi...

This paper compares active and passive cooling systems in tidal turbine power electronic converters. The comparison is based on the lifetime of the IGBT (insulated gate bipolar transistor) power modules, calculated from the accumulated fatigue due to thermal cycling. The lifetime analysis accounts for the influence of site conditions, namely turbul...

Accurate knowledge of the input torque in wind turbine gearboxes is key to improving their reliability. Traditionally, rotor torque is measured using strain gauges bonded to the shaft. Transferring the resulting signal from the rotating shaft to a stationary data acquisition system while powering the sensing devices is complex and costly. The magni...

Downsizing the Power Takeoff (PTO) rating has been proven to be beneficial for decreasing the Levelized Cost of Energy (LCOE) of wave energy converters (WECs). However, the linear permanent magnet (PM) generator has not yet been modelled and optimized in detail in previous feasibility studies. This paper extends the study of the PTO downsizing to f...

This paper presents the state-of-the-art technologies and development trends of wind turbine drivetrains – the energy conversion systems transferring the kinetic energy of the wind to electrical energy – in different stages of their life cycle: design, manufacturing, installation, operation, lifetime extension, decommissioning, and recycling. Offsh...

Ship hybridization has received some interests recently in order to achieve the emission target by 2050. However, designing and optimizing a hybrid propulsion system is a complicated problem. Sizing components and optimizing energy management control are coupled with each other. This paper applies a nested double-layer optimization architecture to...

Doubly fed induction generator (DFIG) based wind turbines are most employed for onshore applications because of their cost-effectiveness. The drivetrain improvement is barely studied due to the maturity of the DFIG based systems. This paper investigates two methods for improving the annual energy production (AEP) of the DFIG based wind turbines. Th...

Currently, the techno-economic performance of Wave Energy Converters (WECs) is not competitive with other renewable technologies. Size optimization could make a difference. However, the impact of sizing on the techno-economic performance of WECs still remains unclear, especially when sizing of the buoy and Power Take-Off (PTO) are considered collec...

2020 年洋山四期工程航道维护疏浚项目为洋山 四期港内水域和港内航道疏浚，其中港内水域包括 洋山四期连接水域和回旋水域， 维护长度约 3.55km， 维 护 宽 度 250m-1550m， 水 域 面 积 约 336.6 万 m 2 ；港内航道维护长度约 2.15km，宽度由 250m 逐渐缩窄，水域面积约 26.9 万 m 2 ，疏浚底标高均 为-15.5m，工程量为 258.08 万 m 3 ，中港疏浚公司 共投入"新海虎"轮、"新海虎 4"轮两艘万方耙 吸挖泥船。中交上航局承担了洋山港四期航道紧急 疏浚作业，工程投入两艘大型耙吸挖泥船，每船每 天疏浚作业能力达 5 万 m 3 。为保证作业安全，船舶 施工时需密切关注洋山港区附近 3 个锚地、5 个码头和 8 条航道的船舶动态，确保保...

PTO (Power Take-off) systems in WECs (Wave Energy Converters) are generally overrated with regard to the average extracted power, which is not economically favorable. However, there is no explicit and agreed approach on how to limit the PTO capacity without damaging WECs. In this work, a generic point absorber and direct drive PTO are used as resea...

A sound maintenance strategy is significant for wind energy development, because it can strengthen the competitiveness of wind power. The design and development of maintenance strategies for wind energy is a complicated topic which involves failure modes, degeneration process, weather conditions, spare parts management, accessibility for repair, av...

The gearbox is a critical component of modern MW wind turbines. An accurate model of the gearbox dynamics is needed to improve gearbox design, develop advanced control algorithms, and more effective fault diagnosis tools which could lead to lower the cost of energy from wind. The objective of this paper is to investigate how torque measurements can...

Dynamic pricing can be used for better fleet distribution in free-floating vehicle sharing (FFVS), and thus increase utilization and revenue for the provider by reducing supply-demand asymmetry. Supply-demand asymmetry refers to the existence of an undersupply of vehicles at some locations at the same time as underutilization of vehicles at other l...

In this paper, a fair evaluation method of WECs (Wave Energy Converters) is established based on frequency domain simulation. In this fair evaluation, size optimization and downsizing of PTO (Power TakeOff) capacity are included to minimize the Cost of Energy for the concerned wave location. Based on this fair evaluation, a techno-economic evaluati...

Thermal cycling is one of the major reasons for failure in power electronic converters. For submerged tidal turbine converters investigating this failure mode is critical in improving the reliability, and minimizing the cost of energy from tidal turbines. This paper considers a submerged tidal turbine converter which is passively cooled by seawater...

Improving availability of tidal turbines has been identified as a key area to lower the levelized cost of energy from tides. One of the approaches suggested to achieve high reliability is to use a flooded permanent magnet (PM) generator. Flooded PM generators are designed to operate with a seawater filled stator-rotor gap of the generator. Using su...

Tidal energy is predictable, which makes it highly attractive from the grid integration point of view. Recent years have seen the growth of the tidal current turbines over the traditional tidal range technology. This is primarily because of the success of the wind turbines, which are in principle similar to the tidal current turbines, and the high...

Historic records show that the cost of operating and supporting an aircraft may exceed the initial purchase price as much as ten times. Maintenance, repair and overhaul activities rep- resent around 10-15% of an airlines annual operational costs. Therefore, optimization of maintenance operations to minimize cost is extremely important for airlines...

In order to avoid detection by sea mines, the magnetic signature of merchant and naval vessels can be reduced by running a current through a set of on-board copper coils. This process is called degaussing. Studies have shown that the volume, weight and energy losses of a degaussing system can be reduced by replacing the copper coils with high tempe...

Historic records show that the cost of operating and supporting an aircraft may exceed the initial purchase price as much as ten times. Maintenance, repair and overhaul activities represent around 10-15% of an airlines’ operational costs. Therefore, optimization of maintenance operations is extremely important for airlines in order to stay competit...

The study presents a newly generated hindcast database of metocean conditions for the region of the North Sea by parametrising the newly introduced ST6 physics in a nearshore wave model. Exploring and assessing the intricacies in wave generation are vital to produce a reliable hindcast. The new parametrisations perform better, though they have a hi...

To properly assess the energy and waves at a region, it is vital to obtain suitable long term metocean conditions. Although, wave buoys are a significant source of information they are not able to provide a detailed and complete resource assessment, as they have inherent spatio-temporal and recording limitations. Therefore, numerical wave models ar...

With the renewable targets of 2020 reaching ever closer, Europe is continuing its ambitious plans for 2030 of developing innovative projects that assist tackling climate change and increase renewable energy integration. The Netherlands are trying to develop their renewable energy portfolio, to create a viable long-term decarbonized sustainable soci...

It is expected that several identical Point Absorber Wave Energy Converters (PAWECs) will be arranged in arrays to form a Wave Energy Farm. One of the key challenges in designing such a WEC array is their spatial configuration, as the WECs in the farm interact hydrodynamically with each other. This study focuses on different potential PAWEC deploym...

Serious initiatives for high speed transport of vehicles/pods/capsules through evacuated tubes were presented in recent years. Most suggest magnetic levitation and linear motors of long-stator design, assuming passive pods. This paper takes a the different approach, yielding minimal energy use per distance per passenger and lowest initial cost. An...

This paper proposes a simplified approach to model the thermal behavior of the insulated gate bipolar transistors (IGBTs) in a subsea power electronic converter. The models are based on empirical relations for natural convection in water, and IGBT datasheet values. The proposed model can be used in the design of subsea converters and in the reliabi...

The power electronic converter, especially the power semiconductor, is a major contributor to the failure rates of the wind turbine drivetrain. As the temperature is a major driving factor behind the failure mechanisms of these power semiconductors the choice of topology and switching strategy can have a significant effect on the reliability of the...

Modularity is promising from a view to increasing turbine availability through fault tolerant operation as well as reduced downtimes, especially for offshore wind turbines. This paper focuses on a quantitative analysis of large scale (or extreme) modularity in power electronic converters of wind turbine generator systems. It uses mathematical model...

A method for comparing the levelized cost of energy (LCoE) of different superconducting drive trains is introduced. The properties of a 10-MW MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> superconducting direct-drive generator and the cost break down of the nacelle components are presente...

Keywords Electric vehicle propulsion systems and their energy storage, Electric propulsion systems for electric vehicles, Electrical machines and drive systems, Adjustable speed drives Abstract Battery electric vehicles (BEVs) have the potential to replace conventional vehicles, but the short driving range is currently limiting their diffusion. Usi...

The brushless Doubly-Fed Induction Machine, without brushes and slip-rings, is regarded as an attractive alternative to the conventional Doubly-Fed Induction Machine in terms of reliability. This paper presents a sensorless field oriented control strategy for the Brushless-DFIM, which further increases its attractiveness as a drive system.With the...

This paper aims at assessing the potential of partially superconducting generators for 10 MW direct-drive wind turbines by investigating their performance for a very wide range of excitation currents. Performance indicators such as shear stress and efficiency and other generator characteristics are compared for 12 different generator topologies. To...

This paper aims at finding feasible electromagnetic designs of superconducting synchronous generators (SCSGs) for a 10-MW direct-drive wind turbine. Since a lower levelized cost of energy (LCoE) increases the feasibility of SCSGs in this application, 12 generator topologies are compared regarding their LCoE in a simplified form of levelized equipme...

Direct drive high temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits happen at generator terminals. In this paper, a finite elem...

Availability is an important factor to be considered when designing wind turbine generator systems. The quest for increasing availability is based on the following five design approaches - design for component reliability, active control for reliability, design for fault tolerance, prognostics, and design for maintainability. This paper reviews met...

A direct-drive superconducting generator (DDSCG) is proposed for 10 MW wind turbines in the INNWIND.EU project. To fit the generator into the ''king-pin'' conceptual nacelle design, the generator structure with inner stationary superconducting (SC) field winding and outer rotating copper armature winding is investigated in the first research phase....

Superconducting synchronous generators (SCSGs) are drawing more attention in large direct-drive wind turbine applications. Despite low weight and compactness, the short circuit torque of an SCSG may be too high for wind turbine constructions due to a large magnetic air gap of an SCSG. This paper aims at assessing the effects of armature winding seg...

The brushless Doubly-Fed Induction Machine (DFIM) shows great potential as a generator in large-scale wind turbines. The motion of the magnetic field in this machine is not a simple rotation, which makes it not so straight forward to understand its operating principles. This paper develops an analytical magnetic field model for the brushless DFIM t...

The air-gap magnetic fields of brushless doubly fed induction machines (DFIMs) are complicated because of the cross-coupling between two stator fields via a special nested-loop rotor. Compared with classical analytical models, transient finite-element (FE) modeling is easier to evaluate the machine performance taking saturation into account. Howeve...

Brushless doubly-fed induction machines (DFIMs) have great potential as variable-speed generators in wind turbines. Undesired space-harmonics exist because the special rotor needs to couple to two stator windings with different pole-pair numbers and different frequencies. These undesired space-harmonics could lead to noise, vibrations and low power...

The brushless Doubly-Fed Induction Machine (DFIM) is a special machine type that is of interest as a generator in wind turbine drive-trains. The brushless DFIM has a significant space-harmonic content compared to conventional machine types, due to its construction. This results in additional harmonic distortions, such as torque-ripple and time-harm...

The ongoing increase in renewable power generation causes a parallel overall decrease in conventional power generation from, in particular, fossil and nuclear power plants. Apart from providing market-based active power schedules, these power plants are crucial for offering ancillary services in order to guarantee a reliable stable power supply at...

Within this document, electromechanical conversion refers to the components and systems in between the hub and electrical connections. In state-of-the-art wind turbines, electromechanical conversion mostly consists of a combination of a gearbox, a generator and a power electronic converter.

Brushless doubly-fed induction machines have great potential as variable-speed generators in wind turbines. Undesired space harmonics exist because the special rotor needs to couple both stator windings which with different pole-pair numbers and different frequencies. These undesired space harmonics lead to a bigger torque ripple compared with conv...

Brushless doubly-fed induction machines (DFIMs) can be potential variable-speed generators for off-shore wind turbine applications. This special machine has two stator windings with different pole-pairs. There is no direct magnetic coupling between two stator windings. A unique nested-loop rotor is designed to couple both stator windings. However,...

In this paper, the brushless DFIM based wind turbine drive-train topology is compared to the DFIG based and PM generator based drive-train topologies, that are most commonly applied in modern wind turbines. The comparison will be based on a 3.2 MW case study wind turbine. By using FE based multi-objective optimization, optimized generator designs f...

The brushless Doubly-Fed Induction Machine (DFIM) provides an interesting alternative to the commonly applied conventional DFIM in modern multi-MW wind turbines. This paper presents a literature survey on the brushless DFIM. The evolution of the cascaded induction machine into the modern brushless DFIM is discussed, as well as several theories expl...