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     

风力发电机组对称短路特性分析

在电力系统分析软件DIgSILENT/Power Factory中建立风电机组及电力系统模型,包括固定转速风电机组和双馈变速风电机组。设置靠近风电场的三相对称短路故障,对风电机组对称短路特性进行理论与仿真分析,比较了不同类型风电机组与相同容量同步发电机组的短路电流波形。以某区域电网为例计算了风电场接入前后其附近母线短路电流,计算风电场接入后使得短路电流增加的百分数,以确定风电场对系统短路电流的贡献。理论分析和仿真结果表明,风电场对并网点附近节点的短路电流有较大影响,在选择风电场附近的电气设备以及对其进行热稳定性校核时,需要考虑风电场对系统短路电流的贡献。     

并网永磁直驱式风电系统的模态分析

为研究永磁直驱风电系统（PMSG）并网后自身的稳定性问题,进行了并网风电系统的模态分析。建立了适用于系统小扰动稳定分析的PMSG风电系统模型,研究了并网风机无穷大系统的模式特性。采用特征值法分析了轴系模型、轴系刚性参数、运行点、并网距离对并网风电系统模式的影响。并在PSCAD/EMTDC上建立了相应的非线性模型,利用Prony方法对输出功率曲线进行模式识别,验证了模态分析结论。研究从模态分析的角度说明了轴系双质块建模的重要性,以及上述参数对并网PMSG稳定性影响的相关结论,结果有助于了解并网PMSG风电系统稳定性问题的本质。     

基于风力机特性的风电机组潮流计算

在风力机特性方程和异步发电机的稳态等值模型基础上,建立了基于风力机特性的风电机组潮流计算数学模型。考虑风力机特性方程中的风力机机械力矩和发电机电磁力矩平衡,将风电机组引入处作为功率可变的PQ节点,异步发电机则作为RX等值电路模型,进行了风电机组的潮流计算。该方法引入定子电压,定子电流和转子滑差的修正量,将风力机特性方程中的风速、风能利用系数、尖速比等相关参数引入到潮流计算过程中,通过与常规的牛顿-拉夫逊潮流计算相结合,修正相应的雅可比矩阵来完成,从而保证了潮流计算迭代过程的完整性。该模型既具有传统风电机组RX模型的优点,又可以保证牛顿-拉夫逊方法的平方收敛性。最后,通过2个算例进行了潮流计算,证明了其正确性。     

基于风电机组常见故障的模糊FMECA评价研究

针对风力发电厂运行可靠性问题,提出风电机组模糊故障模式、影响与危害性分析(Failure Modes, Effect and Criticality Analysis, FMECA)评价模型。基于金风天翼风电场全年运行数据的统计分析,对风电机组故障评价引进模糊评价理论进行改进。通过建立FMEA(Failure Mode and Effect Analysis, FMEA)故障表,绘制危害性矩阵图并建立因素集、评价集和权重集,进行模糊评价分析。根据评价结果,对各故障的危害度进行重新排序整理。该研究对进一步提高风电现场运维效率、降低运维成本具有重要的意义。     

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     

大型变速恒频风电系统的建模与仿真

针对兆瓦级变速恒频风力发电系统,基于Matlab/Simulink建立了包括风机、传动齿轮、双馈发电机在内的大型风电系统的整体动态数学模型。传统的最大风能捕获算法往往基于最优功率曲线和部分风机参数已知,当上述参数未知或出现扰动时,风电系统的效率会严重降低。针对此不足,基于所建模型设计了变步长最大风能捕获控制器,该控制器采用矢量控制算法,实现了发电机输出有功和无功功率的解耦控制;针对有功功率控制,控制器根据发电机输出转速扰动时,相应输出有功功率的变化变步长地调整系统输入,直到系统运行到最大风能点。仿真结果验证了风电系统模型的正确性以及控制器的有效性。     

融合集对分析和证据理论的风电机组运行状态评估

为及时准确地评估风电机组运行状态,结合集对分析和证据理论各自的特点提出了一种风电机组运行状态评估的新方法。该方法根据风电场数据采集与监控系统的物理量,构建机组运行状态评估的指标体系,建立了一个2层评价模型。模型第1层采用集对分析处理指标不确定性的劣化度,并生成模型第2层的基本概率分配。模型的第2层采用证据理论进行多证据融合,得到机组运行状态的隶属度,同时基于隶属度最大原则与信度准则共同评判风电机组运行状态等级。采用所提评估方法对某风电场1.5 MW并网风电机组进行状态评估,并将评估结果与传统的模糊综合评估方法得到的结果进行比较,结果表明所提评估方法的结果更准确,在状态的趋势分析中也表现较好。     

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。     

Optimal allocation of wind turbine generator in active distribution network

Nowadays, more and more wind turbine generators (WTGs ) are being integrated into power systems. In this paper, an optimal WTG allocation model with the objective of minimizing the annual cost is proposed. The model can take into account the time‐sequential correlation between the wind speed and load demand, as well as four kinds of active management measures, i.e. regulating the on‐load tap changer of the transformer, curtailing the output power of WTG , regulating the power factor of WTG , and managing the demand side. The time‐sequential correlation is handled by the joint probability distribution method. A hybrid solving strategy combining the fuzzy adaptive particle swarm optimization algorithm and primal‐dual interior point method is developed to get the optimal solutions. Case studies carried out on the IEEE 33‐bus active distribution network verify the feasibility of the developed model and the high efficiency of the proposed solving strategy. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

含不同风电机组的风电场暂态运行特性仿真研究

随着大容量风电场集中接入电网,有必要研究含不同风电机组参数和类型的风电场暂态特性及对电网的影响。在分析笼型异步和双馈异步风电机组暂态模型的基础上,分别建立了含不同风电机组的风电场容量加权等值模型。从风电机组不同容量比、风电场不同短路容量比以及电网联络线不同阻抗比角度,对含不同风电机组的风电场暂态运行特性进行仿真。仿真结果表明：在电网接受风能容量一定的条件下,双馈异步风电机组装机容量比例提高以及风电场短路容量比和联络线阻抗比的降低,都可以提高和改善风电场出口处电压和机组的暂态稳定性。     

Wind turbine emulator based on blade element momentum theory for variable‐speed wind power generation system

This paper proposes a wind turbine emulator (WTE) based on the blade momentum theory, and tests the variable‐speed wind power generation system using a pulse‐width modulation (PWM) converter to verify the accuracy of the emulator. The behavior of the wind turbine for natural wind is reproduced by the WTE based on the proposed theory. The variable‐speed wind power generation system employs a vector control system to control the torque and speed of the permanent magnet synchronous generator in the converter side. The windmill rotational speed is controlled to maximize the efficiency of the wind turbine against wind velocity. And the active power and reactive power are controlled in the inverter side, and the generated power is sent to the grid while controlling the DC link voltage to be constant at the same time. The behaviors of the WTE are compared with the simulation results and experimental results using a real wind turbine. These experimental and simulation results show that the test bench with the proposed WTE has sufficient performance and accuracy to verify variable‐speed wind generator systems. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

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     

Rigorous analyses of a power distribution system with distribution transformer banks serving unbalanced loads and wind turbine generator systems

Three‐phase power distribution transformer banks (DTrBs) are widely applied to serve single‐phase lighting loads and three‐phase power loads in a medium‐voltage three‐phase four‐wire (3Φ4W) power distribution systems simultaneously. Furthermore, the growing small‐scale wind turbine generator (WTG) systems are directly connected to the secondary side of DTrBs. It has been found that the system imbalance of a power distribution system might be significantly enlarged when WTGs are operated in parallel. Because of the determination the system imbalances of these systems are extremely complicated. In this paper, we introduce an effective method to develop the mathematical models of asymmetrical DTrBs, rigorously. These models can be easily applied in an unbalanced 3Φ4W power distribution system for more detailed analyses. In addition, such a kind of unbalanced system will be solved with an aid of the computer program, Matlab^®/Simulink^®, to analyze the effects of system imbalances when an asymmetrical DTrB serves the single‐ and three‐phase loads and the WTG system in parallel operation simultaneously. The simulation results and conclusion are of value to power distribution engineers for better planning, operating, and promoting their distribution system. Copyright © 2016 John Wiley & Sons, Ltd.     

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。