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21 pages, 5881 KiB

Open AccessArticle

Simple and Robust MPPT Current Control of a Wound Rotor Synchronous Wind Generator

by Lucky Dube, Graham C. Garner, Karen S. Garner and Maarten J. Kamper

Energies 2023, 16(7), 3290; https://doi.org/10.3390/en16073290 - 6 Apr 2023

Cited by 6 | Viewed by 2204

Abstract

In the search for efficient non-permanent magnet variable-speed wind generator solutions, this paper proposes a maximum power point tracking (MPPT) current-control method for a wound rotor synchronous wind generator. The focus is on direct-drive, medium-speed wind generators. In the proposed method, the currents [...] Read more.

In the search for efficient non-permanent magnet variable-speed wind generator solutions, this paper proposes a maximum power point tracking (MPPT) current-control method for a wound rotor synchronous wind generator. The focus is on direct-drive, medium-speed wind generators. In the proposed method, the currents of the wound rotor synchronous generator (WRSG) are optimally adjusted according to the generator speed to ensure maximum power generation from the wind turbine without needing information on wind speed. The design, modeling, and simulation of the MPPT current controllers are done in Matlab/Simulink with the WRSG in the synchronous reference frame. The controller is put to the test using different wind speed profiles between cut-in and rated speeds. The simulation results indicate that the proposed current control method is simple, effective, and robust, suggesting its practical implementation. To validate the simulation results, experimental work on a 4.2 kW WRSG prototype system is presented to demonstrate the stability and robustness of the MPPT current control method in operating the turbine at or near the maximum power point. Full article

(This article belongs to the Special Issue Wind Energy Technologies Development)

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18 pages, 6609 KiB

Open AccessFeature PaperArticle

Development and Validation of Control Algorithm for Variable Speed Fixed Pitch Small Wind Turbine

by Donggeun Jeong, Taesu Jeon, Insu Paek and Deokjin Lim

Energies 2023, 16(4), 2003; https://doi.org/10.3390/en16042003 - 17 Feb 2023

Cited by 3 | Viewed by 2203

Abstract

In this study, a power control algorithm of a variable-speed fixed-pitch horizontal-axis lift-type 20 kW small wind turbine (SWT) was proposed and verified through dynamic simulations. The power control algorithm proposed in this study consists of algorithms for Region II to track the [...] Read more.

In this study, a power control algorithm of a variable-speed fixed-pitch horizontal-axis lift-type 20 kW small wind turbine (SWT) was proposed and verified through dynamic simulations. The power control algorithm proposed in this study consists of algorithms for Region II to track the maximum power coefficient, for Region II-1/2 to maintain the rated rotor speed, and for Region III to maintain the rated power. To verify the proposed power control algorithm, simulations were performed at the rated wind speed and above the rated wind speed, to which turbulence intensity based on the IEC regulation’s normal turbulence model was applied. As a result, it was confirmed that the proposed controller operates properly in the whole three regions including Regions II, II-1/2, and III. The controller performance was then compared with the variable-speed variable-pitch power controller. Although the performance of the proposed controller was considered good for the target VSVP wind turbine, it was lower than that of the conventional controller applied to the same wind turbine. Compared to the VSVP wind turbine, the VSFP wind turbine with the proposed controller was found to have higher mean loads on the blade and the tower but the fatigue loads in terms of Damage Equivalent Load (DEL) were found to be reduced. Full article

(This article belongs to the Special Issue Wind Energy Technologies Development)

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15 pages, 4038 KiB

Open AccessArticle

A Study on the Improved Power Control Algorithm for a 100 kW Wind Turbine

by Dongmyoung Kim, Taesu Jeon, Insu Paek, Wirachai Roynarin, Boonyang Plangklang and Bayasgalan Dugarjav

Energies 2023, 16(2), 619; https://doi.org/10.3390/en16020619 - 4 Jan 2023

Viewed by 1484

Abstract

In this study, a power compensation control algorithm was designed and validated for commercial 100 kW medium wind turbine models for power compensation due to additional generator loss. Generally, torque control considering generator efficiency is applied to a controller of a medium wind [...] Read more.

In this study, a power compensation control algorithm was designed and validated for commercial 100 kW medium wind turbine models for power compensation due to additional generator loss. Generally, torque control considering generator efficiency is applied to a controller of a medium wind turbine; however, a control corresponding to a decrease in generator efficiency due to the surrounding environment is not possible. There is a possibility that an additional generator loss may occur due to the surrounding environment of the wind turbine already installed, and accordingly, a power compensation control algorithm is required because power is expected to decrease. The power compensation control algorithms may be divided into three methods according to a control strategy, and three power compensation control algorithms were explained and designed. The proposed power compensation control algorithms were validated using DNV’s Bladed program. The simulation conditions were selected at an average wind speed of about 18 m/s and normal turbulence model (NTM) Class A, and the additional generator loss was assumed to be 15%. The simulation comparison showed that the original power control algorithm had a deviation of 15.00% from the rated power due to a 15% generator loss, and the designed three power compensation control algorithms had a deviation of up to 0.05%. Full article

(This article belongs to the Special Issue Wind Energy Technologies Development)

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18 pages, 1572 KiB

Open AccessArticle

Multi-Objective Non-Dominated Sorting Genetic Algorithm Optimization for Optimal Hybrid (Wind and Grid)-Hydrogen Energy System Modelling

by Esmeralda Mukoni and Karen S. Garner

Energies 2022, 15(19), 7079; https://doi.org/10.3390/en15197079 - 26 Sep 2022

Cited by 11 | Viewed by 2138

Abstract

In this paper, an optimal hybrid (wind and grid)-hydrogen energy system (H-HES) is proposed using multi-objective non-dominated sorting algorithm (NSGA-II) optimization. The H-HES consists of the main energy system; wind-energy system (W-ES), which supplies a proton exchange membrane (PEM) electrolyzer via an energy [...] Read more.

In this paper, an optimal hybrid (wind and grid)-hydrogen energy system (H-HES) is proposed using multi-objective non-dominated sorting algorithm (NSGA-II) optimization. The H-HES consists of the main energy system; wind-energy system (W-ES), which supplies a proton exchange membrane (PEM) electrolyzer via an energy management system (EMS) and a rectifier. In addition, the grid-energy system (G-ES) is available to support the W-ES to meet the PEM electrolyzer’s energy demand, and the EMS facilitates control between the W-ES and G-ES. The W-ES is modelled using wind data from Wind Atlas South Africa (WASA) for six Renewable Energy Development Zones (REDZs) in South Africa and their appropriate wind turbine models. The selection of appropriate wind turbine models is guided by the optimal wind turbine variables obtained from NSGA-II corresponding to the optimal H-HES model. The optimal H-HES model is developed using two objective functions: cost of electricity and efficiency, which are minimized and maximized respectively and evaluated using NSGA-II available in Pymoo framework. NSGA-II successfully converges to a Pareto front, and the best solution for the H-HES cost of electricity and efficiency for each wind REDZ is determined by compromise programming; a multi-criteria decision-making technique available in Pymoo. From the optimal cost of electricity and efficiency solutions, optimal variables are successfully obtained for optimal modelling of the H-HES for each wind REDZ. Full article

(This article belongs to the Special Issue Wind Energy Technologies Development)

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17 pages, 2065 KiB

Open AccessArticle

Modeling and Vector Control of a Cage+Nested-Loop Rotor Brushless Doubly Fed Induction Motor

by Tainton Hutton and Nkosinathi Gule

Energies 2022, 15(14), 5238; https://doi.org/10.3390/en15145238 - 19 Jul 2022

Cited by 1 | Viewed by 1367

Abstract

The brushless doubly fed induction machine (BDFIM) is being considered as a possible solution for low-speed wind energy generator applications. It has been proposed as an alternative to the doubly fed induction machine (DFIM) due to its robust rotor structure as well as [...] Read more.

The brushless doubly fed induction machine (BDFIM) is being considered as a possible solution for low-speed wind energy generator applications. It has been proposed as an alternative to the doubly fed induction machine (DFIM) due to its robust rotor structure as well as low operational maintenance requirements. However, due to its complicated control philosophy, higher overall machine size due to the extra set of control windings in the stator, and slightly lower efficiency, it is yet to be adopted in commercial applications. In this paper, a simplified vector control scheme for the control winding of a cage+nested-loop (cage+NL) rotor BDFIM is proposed. Experimental results are compared with simulations to validate the effectiveness of the proposed control scheme. Full article

(This article belongs to the Special Issue Wind Energy Technologies Development)

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17 pages, 14605 KiB

Open AccessArticle

Aerodynamic Interactions of Wind Lenses at Close Proximities

by Sidaard Gunasekaran, Madison Peyton and Neal Novotny

Energies 2022, 15(13), 4622; https://doi.org/10.3390/en15134622 - 24 Jun 2022

Viewed by 1460

Abstract

The fundamental aerodynamic interactions between a pair of wind lenses is experimentally investigated. In prior work, wind tunnel testing of lensed turbines in a side-by-side configuration revealed that one lensed turbine outperformed its counterpart in terms of power production. In the current study, [...] Read more.

The fundamental aerodynamic interactions between a pair of wind lenses is experimentally investigated. In prior work, wind tunnel testing of lensed turbines in a side-by-side configuration revealed that one lensed turbine outperformed its counterpart in terms of power production. In the current study, particle image velocimetry (PIV) was performed in the wake of three different pairs of wind lens profiles and revealed an inherent bias in the wake properties at close proximities which led to one turbine outperforming the other. The merged wake location is skewed to a single lens in the lens pair depending on the extent of cancellation of inboard vorticity magnitude. At 0.1 to 0.2

x / D

,the individual wakes merge as one, at which point the vortex shedding frequency and the modal strength behind the lens pairs is reduced. Coincidentally, it is at this spacing that the net power output of lensed turbines placed in a side-by-side configuration reaches the maximum. Full article

(This article belongs to the Special Issue Wind Energy Technologies Development)

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20 pages, 6491 KiB

Open AccessArticle

Design and Evaluation of a Laminated Three-Phase Rotary Transformer for DFIG Applications

by Stefan Botha and Nkosinathi Gule

Energies 2022, 15(11), 4061; https://doi.org/10.3390/en15114061 - 1 Jun 2022

Cited by 2 | Viewed by 2005

Abstract

In doubly fed induction generators (DFIGs), the rotor is excited through slip-ring and brush assemblies. These slip-ring and brush assemblies often require frequent routine maintenance, which affects the reliability of the DFIG. Alternatively, a contact-less energy transfer system, such as a rotary transformer, [...] Read more.

In doubly fed induction generators (DFIGs), the rotor is excited through slip-ring and brush assemblies. These slip-ring and brush assemblies often require frequent routine maintenance, which affects the reliability of the DFIG. Alternatively, a contact-less energy transfer system, such as a rotary transformer, can be utilized in place of the slip rings. In DFIGs, the rotor frequency is very low, under 5 Hz, and this can lead to a huge rotary transformer since the transformer size is inversely proportional to its operating frequency. However, in a rotor-tied DFIG, whereby the rotor is connected directly to the grid whilst the stator is connected to a back-to-back converter, the rotor frequency becomes the grid frequency and can lead to a reasonably sized rotary transformer. In this paper, the design methodology of a three-phase rotary transformer that can be used in rotor-tied DFIG applications is proposed. The rotary transformer is coupled to the power windings of the rotor-tied DFIG and can improve its reactive power capabilities. The proposed methodology is validated with finite element analysis in 3D and can be used for an efficient design process with the proposed error correction. The proposed methodology is then applied in the design of a 6 kVA rotary transformer. Remarkable practical results are presented to demonstrate the effectiveness of the methodology. The rotary transformer is subsequently coupled to a rotor-tied DFIG and an acceptable performance is demonstrated for the entire system. Full article

(This article belongs to the Special Issue Wind Energy Technologies Development)

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23 pages, 5458 KiB

Open AccessArticle

On the Design and Topology Selection of Permanent Magnet Synchronous Generators for Natural Impedance Matching in Small-Scale Uncontrolled Passive Wind Generator Systems

by Casper J. J. Labuschagne and Maarten J. Kamper

Energies 2022, 15(5), 1888; https://doi.org/10.3390/en15051888 - 4 Mar 2022

Viewed by 2923

Abstract

Small-scale uncontrolled passive wind generator systems are an attractive solution for rural energy generation because of the system’s reliability and low cost. However, designing these uncontrolled wind generators for good power matching with the wind turbine is challenging and often requires external impedance [...] Read more.

Small-scale uncontrolled passive wind generator systems are an attractive solution for rural energy generation because of the system’s reliability and low cost. However, designing these uncontrolled wind generators for good power matching with the wind turbine is challenging and often requires external impedance matching. In this paper, permanent magnet generators with different stator and rotor structures were investigated and designed to increase the generator’s synchronous inductance for a natural impedance matching. For the design methodology, multi-objective optimisation was used to design the generators for near-maximum turbine power matching, whereby internal impedance matching was reached as much as possible. It was shown that altering the placement and orientation of the permanent magnets in the rotor is a viable method to achieve the desired impedance matching; however, these generators do not have the best performance. It was found that the surface-mounted permanent magnet generator with semi-closed slots was the optimum topology. An optimised generator prototype was tested for the experimental validation. All designs were verified by comparing the results of 2D and 3D finite-element analysis. Full article

(This article belongs to the Special Issue Wind Energy Technologies Development)

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Review

Jump to: Research

25 pages, 7005 KiB

Open AccessReview

Integration of Switched Reluctance Generator in a Wind Energy Conversion System: An Overview of the State of the Art and Challenges

by Zeineb Touati, Manuel Pereira, Rui Esteves Araújo and Adel Khedher

Energies 2022, 15(13), 4743; https://doi.org/10.3390/en15134743 - 28 Jun 2022

Cited by 12 | Viewed by 2292

Abstract

This paper presents a technical overview for Switched Reluctance Generators (SRG) in Wind Energy Conversion System (WECS) applications. Several topics are discussed, such as the main structures and topologies for SRG converters in WECS, and the optimization control methods to improve the operational [...] Read more.

This paper presents a technical overview for Switched Reluctance Generators (SRG) in Wind Energy Conversion System (WECS) applications. Several topics are discussed, such as the main structures and topologies for SRG converters in WECS, and the optimization control methods to improve the operational efficiency of SRGs in wind power generation systems. A comprehensive overview including the main characteristics of each SRG converter topology and control techniques were discussed. The analysis presented can also serve as a foundation for more advanced versions of SRG control techniques, providing a necessary basis to spur more and, above all, motivate the younger researchers to study magnetless electric machines, and pave the way for higher growth of wind generators based on SRGs. Full article

(This article belongs to the Special Issue Wind Energy Technologies Development)

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