Direct measurement of lightning current through a wind turbine generator structure

The development of a wind turbine generator system in Japan is regarded as a promising source of clean energy, and its popularization is rapidly increasing. In Japan, there are many wind turbine generator systems installed on the Sea of Japan coast, with large wind capacity. However, since the Sea of Japan coast is a region with abundant winter lightning, a phenomenon peculiar to Japan, the wind turbine generator systems are subject to damage from winter lightning. Thus, it is important to observe the lightning currents striking wind turbine generator systems in order to provide lightning protection. The authors therefore installed currents sensors (Rogowski coils) on wind turbine generators installed in Hokkaido and Kagoshima Prefectures, and performed waveform observation of lightning stroke current in the winter of 2002 and the summer of 2003. These observations yielded a few current waveforms for lightning striking wind turbine generators. This paper describes the investigation and presents the observation results. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(4): 40– 47, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20250     

Matching between straight‐wing nonarticulated vertical axis wind turbine and a new wind turbine generator

In the current wind turbine generation system, there are substantial problems such as the fact that the maximum power of the wind turbine cannot be obtained in the presence of fluctuating wind speed, as well as high cost and low annual net electricity production (due to mismatch between generators and wind turbines). A new wind turbine generator optimized for the wind turbine output is presented in order to solve such problems. This wind turbine generator consists of a permanent magnet generator, a reactor, and a rectifier, and uses neither a control circuit which requires standby electricity nor a PWM converter having a switching element. By selecting the most appropriate combination of a permanent magnet generator with multiple windings and a reactor connected in series with each winding, the maximum output of the wind turbine can be obtained without using a control circuit. The new wind turbine generator was directly coupled with a straight‐wing nonarticulated vertical‐axis wind turbine (SW‐VAWT), and matching of the generator with the wind turbine was examined in field tests. The test results and review confirm that the new wind turbine generator is highly matched with the wind turbine in the presence of fluctuating wind speed. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(2): 26–35, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21036     

基于变论域模糊控制的大型风电机组偏航系统

风力发电在解决能源和环境问题上的积极意义,使其成为增长速度最快的绿色能源之一。偏航控制是大型风力发电机组的热门研究课题,偏航系统是典型的非线性、时变系统,常存在较大程度的参数变化和大时变负载与干扰。本文提出一种变论域模糊偏航控制策略,将变论域模糊控制与风向标反馈控制相结合,将风向数据与功率数据进行迅速的对比识别处理,来实现变论域模糊控制参数自整定和控制规则的自调整,提高偏航控制系统对风速扰动和参数变化的适应能力,最后进行风电机组偏航控制的仿真与实验,证明变论域模糊偏航控制具有动态响应快、抗干扰能力和鲁棒性强等优点。     

State criterion of wind turbine generator operation using tower shadow effect (Part 2)

In order to obtain wind energy effectively, the pole‐change‐type induction generators are used as the wind turbine generators. Otherwise, the pole‐change‐type induction generator causes the voltage dips at pole changing time. To maintain the power quality, it is important to know the state change of the generator operation. Therefore, the authors have studied a state criterion of generator using the tower shadow effect, which is the active power oscillation caused by a rotation torque drop when the tower and the turbine blade overlap each other. In this paper, an improved identification method of oscillation frequency, which is the criterion of wind turbine generator operation, is proposed. The proposed method is applied to measured data and good results are obtained. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 25–31, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20395     

风电场机型选择中的技术经济评价指标

风机的选型直接关系到风电场建设项目的投资效益,甚至投资成败,通过对风电场资源条件及各型风机技术性能的分析,提出了对风电场进行整体技术经济分析的"技术经济评价指标"。以"技术经济评价指标"分析不同风机对风电场场址的适应性和性价比,分析了影响风机机型选择的各项因素。可用于风电场前期机型选择或风机设备采购评标工作。     

双驱风力发电机的并网建模与仿真

风力发电机的有功功率和无功功率的解耦控制一直被认为是变速恒频风力发电系统的关键技术。为进一步提高供电质量、减少功率损耗,需要双驱电机拥有控制和分配有功及无功功率的能力。针对双驱电机并网情况,选择合适的坐标变换,应用定子磁链定向的矢量控制方法,完成有功功率和无功功率的解耦工作,实现两者的独立调节。应用Matlab/simulink仿真工具,建立双驱风力发电机的并网模型及解耦模块,仿真结果充分证明了该理论的正确性。     

Current waveform distortion of doubly‐fed generator for wind turbine application by spatial higher harmonics

This paper describes a method to analyze higher harmonic currents resulting from higher space harmonics, depending on the winding pattern of a doubly‐fed generator. A 1.5‐MW generator was used for the analysis, and the results are compared using finite element magnetic field analysis and measurements. The result revealed that the proposed analysis, which focuses on the winding pattern and takes into account higher space harmonics, allows us to calculate higher harmonic currents at high precision, understand the mechanism of changing higher harmonic currents due to the slip or the load of the generator and considerably reduce higher harmonic currents at the armature by restricting higher harmonic currents at the magnetic field. In addition, the sensitivity analysis of design parameters clarified the relationship between current distortion and basic characteristics on electric designs. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 79–85, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20606     

Development of trouble diagnosis technology of 50‐W‐grade micro wind turbine generator

The establishment of an early trouble diagnosis system is needed in order to prevent damage to wind turbine generators. Therefore, acoustic emission (AE) signals resulting from damage to a wind blade were detected with an AE sensor installed on the body of the wind turbine generator and on the mounting pole. In this study, the length of a blade of a micro wind turbine generator was varied to simulate trouble at constant wind velocity. The AE signals which occurred at this time were measured with an AE sensor. The signal was processed by FFT analysis, and the change of spectral strength was examined. A trouble diagnosis technology for 50‐W‐grade micro wind turbines generator was then developed. A method of counting the number of occurrences of above‐threshold AE signals was suggested by the wave pattern of the AE signals. It was found that the number of occurrences could be used as a standard to judge the normality or abnormality of 50‐W‐grade micro wind turbine generators. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(1): 33–39, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21017     

直驱型永磁风电机组并网控制系统的研究

对直驱型永磁风电机组并网控制系统工作结构与原理进行讨论,并研究变流器电机侧与电网侧的并网控制电路与控制策略。应用并联多变流器的方法,采取电网电压定向的电流、电压双闭环矢量控制模式,设计逆变并网控制。基于对交-直-交背靠背双PWM变流器的控制,运行软件仿真了690 V/2.5 MW直驱型永磁风电机组的变流器并网过程。实验结果表明,控制电路与策略正确有效,并网变流器能进行双向的能量传递,并且具有良好的静动态特性。     

风电机组变桨后备VRLA电源在线监测系统

风电机组变桨后备VRLA电源对风电机组安全运行至关重要,结合蓄电池监测维护的实际需求,在不干预现有系统充放电过程下,设计了一套完整的后备电源在线监测系统:在风机端,系统前置设备以TMS320F2812为核心,实现了蓄电池放电高频数据采样与处理;在集控端,采用风机后备动力系统综合监测方法,实现了蓄电池性能及其负载状态的实时远程监测。     

Dynamic response of doubly fed induction generator variable speed wind turbine under fault

The performance of doubly fed induction generator (DFIG) variable speed wind turbine under network fault is studied using simulator developed in MATLAB/SIMULINK. Simulation results show the transient behavior of the doubly fed induction generator when a sudden short circuit at the generator bus is introduced. After the clearance of the short-circuit fault the control schemes manage to restore the wind turbine's normal operation. The controller performance is demonstrated by simulation results both during the fault and after the clearance of the fault. A crowbar is used to protect the rotor converter against short-circuit current during faults.     

Output power control of wind turbine generator by pitch angle control using minimum variance control

Effective utilization of renewable energies such as wind energy as a replacement for fossil fuels is highly desirable. Wind energy is not constant and wind generator output is proportional to the cube of the wind speed, which causes the power output of wind turbine generators (WTGs) to fluctuate. In order to reduce output power fluctuations of wind farms, this paper presents an output power leveling control strategy for wind farms based on both the mean and the standard deviation of wind farm output power, a cooperative control strategy for WTGs, and a pitch angle control method using a generalized predictive controller (GPC) intended for all operating regions of WTGs. Simulation results using an actual detailed model for wind farm systems show the effectiveness of the proposed method. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 154(2): 10–18, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20247     

直驱永磁同步风电机组不对称故障穿越的研究

分析电网发生不对称故障对直驱永磁风力发电机组(D-PMSG)的影响,研究其控制策略,以提高其不对称故障穿越的能力。把电网电压实时引入机侧整流器参考功率的计算中,提出了按照电网正序电压和其额定电压的比减小发电机输出功率的控制策略。建立了经背靠背双PWM变流器并网的D-PMSG仿真模型。机侧整流器控制内环采用电流前馈控制,外环采用功率环控制发电机输出功率。网侧逆变器控制内环采用电流前馈控制,并控制负序电流为零,外环采用电压环稳定直流电压。仿真结果表明,在不对称故障时,这种策略保持了发电机功率平衡和变流器功率平衡,限制了直流电压的升高,保持了逆变器三相电流对称,实现了机组不对称故障穿越。     

真驱永磁同步风力发电机组低电压穿越控制策略

分析直驱永磁同步风力发电机组（DDPMSG）在电网故障情况下的低电压运行特性,提出一种综合控制策略．包括通过变桨距控制实现最大风能追踪：控制发电机电磁功率以控制直流链及电网侧逆变器的功率;利用发电机侧功率控制网侧变流器的电流,实现直流链电压的稳定,以提高直驱永磁同步风力发电机组的低电压穿越能力,维持所并电网的运行稳定性。运用仿真分析软件PSCAD／EMTDC建立DDPMSG及其控制策略的仿真模型,仿真结果验证了所提策略的有效性和可行性。     

A study of the flywheel capacity of the power compensator for the wind turbine generator

Nowadays, the Wind Turbine Generator (WTG) system is remarkably increasing as a renewable energy resource in Japan. But in the WTG, the power fluctuations caused by the wind speed fluctuation are the most crucial issue in providing their energy to the utility. It was found that a power compensation system (PCS) of suitable capacity is not yet available. In this paper, the time range and standardized wind speed including fluctuations are discussed. We estimated the storage capacity of PCS at different wind profiles by standardization of wind speed and verified the validity of their capacities using a computer simulation. In this way we determined the suitable capacity of the power compensation system. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(4): 64–71, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10122     

蚁群算法在风电机组变桨控制中的应用

运行在额定风速以上区间时,变速变桨风力发电机组采用恒功率变桨控制方式,由于额定风速至切出风速之间的风速变化范围大且迅速,使得功率波动较大且频繁,传统PID变桨控制器难以达到很好的控制效果。本文提出的蚁群PID变桨控制器,利用蚁群算法的寻优特性来优化PID参数,使得恒功率变桨控制系统更具自适应性和鲁棒性。分析了风机的恒功率变桨控制,然后给出了蚁群算法优化PID参数的策略以及具体实现步骤。仿真与实验结果验证了蚁群PID变桨控制器的良好动态性能,其有效地减缓了额定风速以上风机的功率波动。     

直驱永磁同步风力发电机组低电压穿越控制策略

分析直驱永磁同步风力发电机组(DDPMSG)在电网故障情况下的低电压运行特性,提出一种综合控制策略,包括通过变桨距控制实现最大风能追踪;控制发电机电磁功率以控制直流链及电网侧逆变器的功率;利用发电机侧功率控制网侧变流器的电流,实现直流链电压的稳定,以提高直驱永磁同步风力发电机组的低电压穿越能力,维持所并电网的运行稳定性。运用仿真分析软件PSCAD/EMTDC建立DDPMSG及其控制策略的仿真模型,仿真结果验证了所提策略的有效性和可行性。     

汽轮发电机转子改造

对200MW以下汽轮发电机,可通过改进转子线圈的通风结构、引线和集电环结构,达到降低损耗、提高效率的目的。并通过性能比较,证明了目前对老机组转子的改造是提高机组性能的一种有效方法。     

内陆风力发电场风机布置方法探讨

提出风电场风机布置的原则.认为不同地理环境条件、风资源条件、地区经济状况都会对风机的布置方案产生影响.对内陆风电场和沿岸滩涂风电场设计中风机布置技术和经济进行了分析比较,并对内陆风场的风机布置提出了一种新的行列距组合选择原则.     

大型汽轮发电机并联环和主引线水路故障分析和预防

大型水氢氢汽轮发电机并联环过热引发的电气事故多次发生，其根源在于水路故障和缺少有效的监测措施。分析和试验表明并联环水路设计是合理的，安装错误和运行不当是引起故障的主要原因，分析引起气堵的各种因素和发展为汽堵的机理，提出预防和改进措施，类似事故是完全可以避免的。