Direct-drive Permanent Magnet Wind Research Articles

Simulation analysis of overvoltage caused by grounded short circuit in the collection system of far-offshore wind farms

Abstract As the distance from the shore of offshore wind farms increases, MMC-HVDC technology is gradually gaining attention in its grid connection schemes. A broadband electromagnetic transient model of offshore wind farms with a total capacity of 800 MW connected to the grid via a flexible direct current transmission system is developed. After three types of grounded short circuit faults occur at different fault positions within the power collection system, the characteristics of overvoltage are obtained and they are analyzed on the basis of considering the low voltage ride-through capability of the direct-drive permanent magnet wind power generator. Combining the two factors of range and amplitude, the results show that the overvoltage phenomenon is the most serious when a two-phase grounded short circuit occurs at the converging busbar, which can be the focus of the study when setting up overvoltage protection.

A control-oriented LPV model of large-scale offshore wind turbines for deloading operation

ABSTRACT This article develops a new control-oriented linear parameter varying (LPV) model, which is a linear state-space model with varying parameters aimed at efficiently representing large-scale offshore wind turbines (LOWTs). Firstly, the LPV model is constructed by the mechanism analysis of a 15-MW direct-drive permanent magnet wind turbine. Subseuently, based on the operational data from FAST, the parameters with unknown values in the LPV model are determined by gain scheduling and parameter estimation. Furthermore, a deloading operation for the active output power regulation of LOWTs is proposed based on coordinating the rotor over-speed control (ROC) and the pitch angle control (PAC).

Improved Maximum Power Point Tracking Control for D-PMSG Systems: Fuzzy Gradient Step Approach

Improved Maximum Power Point Tracking Control for D-PMSG Systems: Fuzzy Gradient Step Approach

Calculation Method and Characteristic Analysis for Fault Current of Permanent Magnet Direct-Drive Wind Power System considering Positive and Negative Sequence Decomposition

In view of the fact that the influence of positive and negative sequence decomposition, which is widely used in positive and negative sequence decoupling control in control system, on the fault current calculation process is not deeply considered in the existing transient analysis methods of permanent magnet direct-drive wind farm short circuit current, this paper proposes a transient short circuit current calculation model that takes into account positive and negative sequence decomposition. The influence of the transient characteristics of positive and negative sequence decomposition on the control system is studied, and the mechanism of its action on the transient change of short circuit current is revealed. The positive and negative sequence decoupling processes of the circuit equation are modified, and the characteristics of the coupling equation are analyzed. The difference in the converter output voltage between the circuit equation and the control equation and the depth of its influence on the calculation process is revealed. On the basis of quantifying the difference at the converter output voltage, the circuit equation and the control equation are combined to form a short-circuit current calculation model with positive and negative sequence decomposition, which accurately characterizes the transient characteristics of fault current under different voltage drops and effectively improves the accuracy of the calculation results.

Optimal wind power generation system by honey badger algorithm with differential evolution strategies

The purpose of this study is to build an optimal hybrid wind power system consisting of a permanent magnet direct-drive wind power generation unit, a hybrid energy storage system (HESS), a power electronic converter, and loads. Moreover, a reasonable control method is designed for each part, and a honey badger algorithm (HBA) with differential evolution strategies is employed to realize the coordinated control of each unit and improve the system stability. The real anti-interference capability of wind power system can be improved by the proposed HBA with differential evolution strategies (IHBA). Firstly, the wind hybrid system model is constructed, in which the wind power generation unit adopts the variable step climbing method to achieve the maximum power point tracking control; the HESS designs the power distribution method based on the bus voltage; the converter supplying energy to the AC load introduces the virtual synchronous generator (VSG) control strategy. Secondly, due to the existence of energy exchange in each unit of the system, VSG has more parameters and its control performance is influenced by the system itself, this study proposes HBA with differential evolution strategies for system parameter optimization and constructs an IHBA-VSG model with the objective of minimizing the bus voltage fluctuation value. The IHBA improves original honey badger algorithm by three mechanisms which are time control function, Gaussian variation factor and differential evolution strategy. Finally, the parameters obtained from the HBA with differential evolution strategies optimization search are substituted into the wind hybrid system, and the simulation system is built by MATLAB/Simulink. The simulation results show that when the environment of the system changes or the load on the AC side changes abruptly, the proposed control method can reduce the bus voltage fluctuation by 2.9%− 18.22% compared with the honey badger algorithm Optimized VSG (HBA-VSG), and can reduce the bus voltage fluctuation by 5.09%− 17.98% compared with the traditional droop control without considering the system interaction. This study can effectively improve the stability of wind power generation system and promote the development of new energy industry.

Inertia control method of direct drive permanent magnet wind turbine under high wind power permeability

Direct-drive permanent magnet wind turbine has high power generation efficiency, especially in low wind speed environment, and is widely used for wind power generation. Direct-driven permanent magnet wind turbines show no inertia response to the system through the grid connection of full-power converters, resulting in increased frequency fluctuation, poor response effect and reduced stability time of the system under sudden load and sudden wind speed conditions. Based on this, an inertia control method of direct-drive permanent magnet wind turbine under high wind power penetration is proposed, and the model of direct-drive permanent magnet wind turbine is built by designing functional modules to improve the synchronous control effect under high wind power penetration. The vector control calculation method is used to design the virtual inertia control parameters, and the decoupling quantity is introduced to decouple the parameters with filter inductance, so as to improve the supporting capacity of power grid frequency fluctuation. The simulation results show that the proposed method has a fast frequency response under sudden load change, and it drops to the lowest value of 49.16 Hz at 12.14 s. Under the condition of sudden change of wind speed, the system frequency rises to the highest value of 50.38 Hz at 12.94 s. It is proved that the proposed method has a certain suppression effect on the amplitude of frequency change, effectively shortens the time for the system frequency to return to steady state, and thus has more advantages.

Environmental Condition Boundary Design for Direct-Drive Permanent Magnet (DDPM) Wind Generators by Using Extreme Joint Probability Distribution

In future engineering applications, it is important for a direct-drive permanent magnet (DDPM) wind generator to be designed with optimized environmental condition boundary. This paper presents a novel extreme joint probability distribution method of boundary design to formulate the evaluation model and correlation between component design and environmental conditions. With this method, the joint probability distributions of multidimensional parameters for typical wind resource areas in China are studied. A 3.3-MW DDPM wind generator is involved in the case study to validate the superiority of the method. Furthermore, to improve the generalizability of the method, some typical wind resource data platforms are calibrated regarding the measured data. It is shown that the ERA5 dataset can be used as a supplement to enhance the representativeness of the measured data for the joint probability distributions. Therefore, the proposed method can be potentially used to optimize the system design of future DDPM wind generators.

Modeling and Control Strategy of Wind-Solar Hydrogen Storage Coupled Power Generation System

Hydrogen production by wind and solar hybrid power generation is an important means to solve the strong randomness and high volatility of wind and solar power generation. In this paper, the permanent magnet direct-drive wind turbine, photovoltaic power generation unit, battery pack, and electrolyzer are assembled in the AC bus, and the mathematical model of the wind-solar hydrogen storage coupled power generation system and the simulation model in PSCAD/EMTDC are established. An energy coordination control strategy is designed. After simulation, the proposed control strategy can effectively reduce the rate of curtailment of wind and solar power, and stabilize the fluctuation of wind and solar power generation. It verifies that the established model is correct and the control strategy is effective and feasible.

Modeling and Grid-Connected Control of Wind-Solar-Storage Combined Power Generation System

Aiming at the complementary characteristics of wind energy and solar energy, a wind-solar-storage combined power generation system is designed, which includes permanent magnet direct-drive wind turbines, photovoltaic arrays, battery packs and corresponding converter control strategies. Simulation analysis is carried out by Matlab/Simulink platform, and the results show that the model of wind and solar storage system is correct and effective, and the grid connection control can be completed.

Non-Conventional, Non-Permanent Magnet Wind Generator Candidates

Global industrialization, population explosion and the advent of a technology-enabled society have placed dire constraints on energy resources. Furthermore, evident climatic concerns have placed boundaries on deployable energy options, compounding an already regrettable situation. It becomes apparent for modern renewable energy technologies, including wind generators, to possess qualities of robustness, high efficiency, and cost effectiveness. To this end, direct-drive permanent magnet (PM) wind generators, which eliminate the need for gearboxes and improve wind turbine drivetrain reliability, are trending. Though rare-earth PM-based wind generators possess the highly sought qualities of high-power density and high efficiency for direct-drive wind systems, the limited supply chain and expensive pricing of the vital raw materials, as well as existent demagnetization risks, make them unsustainable. This paper is used to provide an overview on alternative and viable non-conventional wind generators based on the so-called non-PM (wound-field) stator-mounted flux modulation machines, with prospects for competing with PM machine variants currently being used in the niche direct-drive wind power generation industry.

Support Vector Regression Inverse System Control for Small Wind Turbine MPPT with Parameters’ Robustness Improvement

With the increasing penetration of the permanent-magnet direct-drive wind power system, the maximum wind-energy capture and the generation speed control are more and more important. In the literature, the dynamic performance of the generator speed is well documented by the inverse system method. However, conventional inverse system methods have parameter dependency that is not sufficient to meet the dynamic requirements for permanent magnet synchronous generator (PMSG) speed tracking. Therefore, this paper introduces a support vector regression machine (SVR) method, especially for the inverse system model, which could solve the inaccurate parameters problems. As the SVR has the nonlinear approximation ability to identify and adjust the parameters online, thus, the system robustness could be improved. Finally, the dynamic performance of generator speed is evaluated by using the SVR method. Proposed theoretical developments are verified by the Simulink Test and experimental test.

Optimization of Computer Communication Monitoring System for Wind Turbine Speed

This article first studies the operating principles of wind turbines, focusing on the analysis of the structure and working principles of permanent magnet direct-drive wind turbines. According to the actual needs of the wind power system, the monitoring objects of the monitoring system are determined, and the overall monitoring plan for wind power generation is proposed to realize real-time analysis of the operating characteristics of the wind power system. At the same time, it pointed out the great significance of the wind power generation simulation experiment system and focused on the wind speed modeling. In terms of hardware research and analysis, relevant sensors, high-speed data acquisition cards, etc., were selected, and relevant signal conditioning circuits were designed, and a permanent magnet direct-drive wind power generation system simulation monitoring platform was constructed. In terms of software, LabVIEW was chosen as the design language of the monitoring system, and it pointed out the advantages of using LabVIEW in this monitoring system. Finally, the system uses the laboratory permanent magnet direct-drive wind turbine as the monitoring object. The practicality and accuracy of the system are verified through experiments such as permanent magnet motor power test, motor speed test, database system test, and remote monitoring test. The experimental results show that the monitoring system has a friendly interface and perfect functions and has important practicability and reference in the field of wind power monitoring.

An Enhanced Half-Quasi-Z-Source Inverter for Wind Energy Conversion System with D-PMSG

To solve the problem of the traditional quasi-Z-source inverters with low voltage gain, an enhanced half-quasi-Z-source inverter (E-HQZSI) is proposed and applied to direct-drive permanent-magnet wind power generation systems in this paper. The expression of the boosting factor is deduced, which shows that E-HQZSI has higher voltage gain compared with the QZSI and HQZSI. However, the higher voltage gain of the E-HQZSI will lead to the large distortion of the generator stator current necessarily. In this paper, a periodic shoot-through duty ratio control scheme is proposed to reduce the stator current harmonics for E-HQZSI. According to the change rule of the single-phase stator current, the shoot-through duty ratio is compromised to make that the three-phase stator currents are as close as possible to the sine wave. Finally, the correctness of the theoretical analysis is verified by simulation and experiment.

MADE3D: Enabling the next generation of high-torque density wind generators by additive design and 3D printing

Direct-drive wind turbine generators are increasing in popularity, thanks to recent project developments—especially offshore, where reliability and efficiency are major cost drivers. Yet, high capital costs are forcing many original equipment manufacturers to consider lightweight, high-torque density generators for next-generation multi-megawatt turbines that may be difficult to realize by traditional design or manufacturing methods. In this study, we present a new design framework enabled by advanced machine learning and multimaterial additive manufacturing to perform a magnetic topology optimization that maximizes the torque per rotor active mass for a 15-megawatt direct-drive permanent magnet wind generator. A comparison of the proposed approach against conventional topology optimization demonstrated a significant increase in computational efficiency and accuracy in performance predictions. Results using single and multimaterial compositions for rotor core and magnets identify a wider choice of 3D printable designs for a given specification. A hybrid combination of sintered and dysprosium-free polymer-bonded magnets shows good potential for torque performance by saving material costs up to 8.75%. More than 30% improvement in rotor torque densities is identified which can marginally improve the overall generator torque density. With the rapid evolution of multipowder deposition technolgies, this study can greatly inspire a new paradigm for design-driven manufacturing with novel material compositions and lightweight, low-cost, high-strength multimaterial geometries that were previously unexplored for direct-drive generators.

RETRACTED ARTICLE: Research on subsynchronous oscillation characteristics and suppression strategy of AC network with wind power base

When the wind farm is connected to the power system, certain issues, such as SSO, will be caused, rendering the protection of the power grid unstable. Researchers have found that this situation can be effectively avoided by direct-drive permanent magnet wind power generation. Generates synchronous frequency oscillation is with the help of a grid connection without series compensation. This mode of power generation is part of a new method of subsynchronous oscillation of the wind farm, and the concepts and steps are not explicit. From the point of view of theory, this paper analyzes the causes of its effect, as well as the methods and measures used, and lists the study reports and findings on the synchronous oscillation of grid-connected direct-driven wind farms at home and abroad. At the end of the article, the author also put forward the hypothesis and the imagination of this process. The theory of the wind fire bundling DC transmission system is that the equipment and AC current will communicate, and synchronous electrical oscillation will also occur, and the torsional vibration of the thermal power unit will occur. Our study starts from the investigation of the and explaining the theory behind the wind power and AC network. In combination with the power grid parameter data, the oscillation times of subsynchronous current harmonics in the wind farm are obtained in a specific environment and the conditions of the subsynchronous harmonic generation are analyzed. At the same time, the effect of line harmonic impedance and current oscillation frequency is also simulated.

Research on Control Strategy of Grid-side Converter of Permanent Magnet Direct-drive Wind Turbine

In order to make the permanent magnet direct-drive wind turbines stable and grid-connected operation, a double closed-loop control strategy based on grid voltage-oriented vector and current decoupling is proposed. First, the topology of the grid-side converter of the wind turbine is determined, then the mathematical model of the control strategy is derived, and the parameters of the PI regulator are calculated. Finally, the control strategy is verified by the simulation results. Through the analysis of the experimental results, it is found that the control strategy can achieve the functions of stabilizing the DC bus voltage of the fan and controlling the input power factor, ensuring the stable operation of the fan.

Selection of Wind Turbine Based on Fuzzy Analytic Network Process: A Case Study in China

Wind turbine selection is an evaluation problem involving many factors, such as technology, economy, society, etc., and there exist internal dependencies and circular relationships among these factors. This increases the complexity of the selection problem. At the same time, with the development of wind power technology, the types of wind turbines on the market are increasing. Therefore, it is necessary to establish a scientific and comprehensive evaluation system to guide the selection work. This paper extends the traditional indicator system, selecting a total of twelve evaluation indicators from three aspects: operation reliability, economy, and supplier cooperation. The selected indicators are defined in detail to clarify the relationship between them. Then the triangular fuzzy number is introduced to accurately reflect the preference information obtained from experts, and a fuzzy analytical network process (FANP) model for wind turbine unit selection is constructed by combining fuzzy preference programming (FPP) with analytic network process (ANP). In the end, a case study in China is carried out. Results show that the 2.5 W unit produced by Goldwind obtains the best comprehensive evaluation value, which is consistent with the expanding market share permanent magnet direct-drive wind turbines. This paper could provide references for future wind turbine selection questions.

Design and Parameter Tuning of Nonlinear Active Disturbance Rejection Controller for Permanent Magnet Direct Drive Wind Power Converter System

When the permanent magnet direct-drive wind power converter system is disturbed by the grid side and the motor side, the output voltage of the converter and the DC bus voltage will change suddenly, and the power quality of the grid will deteriorate. The nonlinear active disturbance rejection controller (NLADRC) is used in the grid-connected inverter control system. Because of its ability to estimate and compensate disturbances, it can effectively improve the system's anti-disturbance ability and tracking accuracy. However, NLADRC still has problems such as many parameters to be adjusted and unclear physical meaning. This article explores the influence of various parameters on the dynamic performance of the entire system, and summarizes the direction and law of parameter tuning. At the same time, the frequency domain analysis method is used to express the gain parameter in the expanded state observer in the form of bandwidth, which provides a basis for parameter adjustment in actual engineering. The control algorithm proposed in this article is applied to the 3MW permanent magnet direct-drive wind power experimental platform. The experimental results under various working conditions show that NLADRC can effectively improve the anti-interference performance of the grid-connected inverter.

PMSM low voltage ride through based on Coordinated Control Strategy

Based on the analysis of the operation characteristics of the fault of direct-drive permanent magnet wind turbine and the existing protection strategies, in order to improve the low-voltage operation capability of direct-drive permanent magnet wind turbine, a new coordinated control strategy for low-voltage crossing is proposed in this paper, which includes DC brake system control of unloading circuit, double second-order generalized integral phase-locked control, extracting positive and negative sequence of grid voltage and reactive power control on grid side. Based on the common three-phase symmetrical drop fault and asymmetrical fault caused by single grounding short circuit in power grid, PASCAD simulation experiment is conducted to verify the low voltage traversing ability of wind turbine.

Design and research of cooling system for 2.5 MW permanent magnet wind turbine

In order to solve the problem of excessive temperature rise caused by 2.5 WM permanent magnet wind turbine in operation, this paper designs a heat dissipation system. The combination structure of the heat exchanger and the heat sink was determined, as well as the heat dissipation method of the internal and external cycle isolation heat exchange. The control method and operation mode with Siemens PLC as the core are put forward. The computational fluid dynamics method is utilized to design the air-cooling heat exchanger and the liquid-cooled heat sink of the heat dissipation system. The results show that the cooling pipe gap has a great impact on the liquid cooling effect. The cooling pipe arrangement and piping arrangement of the air-cooled heat exchanger and liquid-cooled radiator are optimized. Finally, taking a 2.5 MW direct-drive permanent magnet wind turbine as an example, four environmental temperatures were selected to test generators in rated power. Verify that the cooling system is designed to meet cooling requirements.