The Control System Simulation of Variable-Speed Constant-Frequency Wind Turbine

In general,Variable-Speed Constant Frequency (VSCF)Wind generation system is controlled by stator voltage orientation method which based on the mathematic model of VSCF Wind generation system and discussed the control strategy.Present the whole dynamic control model of variable-speed wind generator system in MATLAB/ Simulink,and the simulation results confirm the validity and effectiveness of the proposed control strategy.

On maximum power point tracking control strategy for variable speed constant frequency wind power generation

Based on the characteristic of AC-excited variable speed constant frequency(VSCF)wind power generation,the vector control technique was applied in a doubly fed induction generator(DFIG).Maximum wind energy or maximum output power point can be tracked by decoupling control of active power and reactive power.The research result shows that the net power of generation system delivered to grid in maximum wind energy tracking mode is not the most.We presented a novel maximum power point tracking(MPPT)control strategy by analyzing the DFIG mathematic model and power relations which delivered the maximum power to the grid.The maximum power point could be tracked automatically without measuring wind speed in the control strategy and the control was independent of optimal turbine power curve,which had excellent dynamic and static performances and robustness.Simulation and experimental results testify the accuracy and validity of the control strategy.

Study on Hydraulic Transmission of Offshore Low-speed Wind Energy Generator

For offshore hydraulic drive wind turbines,the problems of unsatisfactory speed control and low efficiency at low wind speeds are targeted.A low-speed high-torque radial piston pump is designed to replace the traditional fixed pump with a particular focus on its low-speed performance.The pump is characterized by small internal leakage at low wind speeds and high volumetric efficiency,which is beneficial to improve the power generation efficiency of the system.A new linear control method based on the PID algorithm and feedforward compensation was proposed to obtain the constant speed output control of variable motor at low wind speed.With the model for wind turbine and fixed pump-variable motor main drive system,the system was simulated and experimentally proved to verify the feasibility and anti-interference performance of the system control method at low wind speeds.A promising outcome was obtained on the response characteristics of system power and efficiency at low wind speeds.This can be a powerful technical support for the normal ustility of hydraulic drive wind turbines.

变转速下基于改进多阶概率方法的风电齿轮箱故障诊断研究

阶次跟踪是一种有效的解决变转速故障诊断问题的方法,其关键前提是存在转速信号作为参考。然而,由于强背景噪声和弱谐波关系的影响,现有转速估计方法的准确性和自适应性有待进一步提高。因此,提出一种融合多传感器信号的改进多阶概率方法(MOPA)用以估计瞬时转速。首先,依据不同传感器信号的基频统一性和主导分量差异性,通过时频图瞬时切片归一化融合的方式,构建具有强谐波关系的时频图;其次,为消除时变工况下时频图中横纵方向上的间歇恒频和短时宽频背景噪声,提出滑动消噪方法;最后,基于处理后的时频图执行MOPA,实现瞬时转速自动估计,结合阶次跟踪解决风电齿轮箱变转速故障诊断问题。经实测数据验证,改进MOPA估计的瞬时频率的准确性和自适应性均优于对方法,平均绝对百分比误差为0.56%,均小于对比方法的15.73%、13.99%和1.21%。结合阶次分析诊断了变转速下风电齿轮箱异常。

超级电容参与风电调频的动态响应优化策略

随着风电渗透率的不断提高,电力系统逐步呈现低惯量的特征。低惯量系统在故障时的频率变化率(RoCoF)和最大频率偏差显著增大,传统频率控制方法效果减弱,频率的安全、稳定面临挑战。针对上述问题,先于一次调频动作的快速频率响应(FFR)已成为解决低惯量系统频率稳定问题的重要手段。首先,建立风-火-储电力系统频率响应模型,分析FFR调频资源对低惯量系统频率响应的影响;其次,基于模糊逻辑推理,提出了一种超级电容参与风电调频的储能动态响应优化策略以控制储能,使其能够动态响应系统频率变化,在频率跌落期遏制频率跌落,在频率恢复期调控储能恢复功率以维持荷电状态稳定;最后,对提出的控制策略进行仿真验证。仿真结果表明,所提策略能够利用超级电容快速动态响应系统频率变化,从而为低惯量系统提供功率支撑,弥补风电调频的不足,相较传统的风电机组虚拟惯量控制策略,在减小最大RoCoF及抑制最大频率偏差效果上均有大幅提升。

基于惯量同步的构网型永磁直驱风电机组频率支撑及转速恢复策略

针对风电机组频率响应后有功支撑与转速恢复切换易诱发二次频率跌落的问题,提出了一种考虑转速恢复的构网型风电机组频率支撑策略。首先阐述了构网型风电机组的“惯量同步”原理;其次,基于转子运动方程,分析了构网型风电机组调频及转速恢复策略对频率最低点及二次频率跌落的影响机理;最后,基于PSCAD/EMTDC仿真平台,构建基于惯量同步的构网型风电并网系统,并在不同扰动下验证所提控制策略的有效性。

风力机叶片截面主刚度系数与横向剪应力分析

针对风力机复合材料叶片弯曲与扭转刚度计算,以及当叶片在横向剪力作用下对空心薄壁截面上剪应力的数值计算方法进行研究。现代风力机叶片呈细长扭曲形,翼型截面为薄壁且内部拓扑构型复杂,材料具有各向异性。在应用各类梁模型进行叶片气弹计算和强度校核等力学分析时,叶片截面的刚度系数和截面剪应力分布是必需参数。基于复合材料薄壁结构层合理论和加权平均方法,结合Bredt-Batho剪力理论,考虑了复合材料叶片的剪切腹板效应和翘曲效应,建立了复合材料层合板等效弹性常数与截面刚度系数数值分析算法;根据弹性力学板壳理论,考虑横向剪切和截面翘曲对截面变形的影响,建立了横向剪力引起的剪力流数值计算方法,并开发了相关算法的Matlab程序。分析10 MW风力机叶片主刚度系数和剪力流分布,并对比文献结果,验证了模型的正确性和算法的有效性。

双馈变速恒频风电系统控制研究

文章以双馈异步电机为风力发电的变流器,分析了双馈式变速恒频风电系统在功率因数校正、电网电压畸变及无功补偿方面的控制策略,重点介绍了双馈变速恒频风电场系统,基于功率因数校正的控制方法分析了双馈异步发电机并网运行时电网电压畸变对风力发电系统运行稳定性和电能质量的影响,最后通过仿真验证了控制策略的正确性。仿真结果表明:文章提出的双馈变速恒频风电系统可以有效改善双馈异步电机并网运行时因电压畸变带来的性能下降问题。

考虑频率二次跌落和转速恢复的风电机组柔性频率响应策略

风电机组具备主动频率响应能力成为未来风电并网的前提条件,但频率支撑阶段与转速恢复阶段间控制策略切换不当可能引起系统频率二次跌落。针对这一问题,文中提出一种风电机组柔性频率响应策略。首先,在初始运行点将风电机组非线性模型线性化,分析初始运行点对风电机组出力特性的影响;其次,基于风电机组线性化模型推导包含风电和火电的电力系统频率响应传递函数,分析系统参数对频率响应动态特性的影响;然后,研究频率二次跌落和转速恢复间的矛盾,利用分段函数和Logistic函数构造附加功率参与因子,通过形状系数调节风电机组输出电磁功率;最后,基于MATLAB/Simulink平台进行对比仿真研究。仿真结果表明,所提出的策略在消除频率二次跌落的同时,具有良好的转速恢复过程。

Effective participation of wind turbines in frequency control of a two-area power system using coot optimization

In this paper,load frequency control is performed for a two-area power system incorporating a high penetration of renewable energy sources.A droop controller for a type 3 wind turbine is used to extract the stored kinetic energy from the rotating masses during sudden load disturbances.An auxiliary storage controller is applied to achieve effec-tive frequency response.The coot optimization algorithm(COA)is applied to allocate the optimum parameters of the fractional-order proportional integral derivative(FOPID),droop and auxiliary storage controllers.The fitness function is represented by the summation of integral square deviations in tie line power,and Areas 1 and 2 frequency errors.The robustness of the COA is proven by comparing the results with benchmarked optimizers including:atomic orbital search,honey badger algorithm,water cycle algorithm and particle swarm optimization.Performance assessment is confirmed in the following four scenarios:(i)optimization while including PID controllers;(ii)optimization while including FOPID controllers;(iii)validation of COA results under various load disturbances;and(iv)validation of the proposed controllers under varying weather conditions.

变速恒频水轮机变流量工况下不稳定流动数值模拟

为了研究变流量条件下变速恒频水轮机正常运转时的涡流特性和水动力特性,基于STAR-CCM+软件进行了混流式变速恒频水轮机的水动力特性数值模拟,研究了定流量和正弦流量两种工况下导叶和转轮压力脉动特性和内部流动状态,对旋转速度改变引起的涡旋演化过程进行了可视化展示。结果表明:在低转速时,尾水管进口和转轮交界处存在随转速降低而聚合产生的大尺度涡,但在转速升高后其逐渐破碎、分离,最后消散;叶片靠近叶轮流道入口的吸力面上均存在涡流,尾水管中存在两个涡核中心,且位置随转速改变;无叶空间的压力脉动相对其余位置更剧烈,脉动幅值随着转速和流量的增大而增大。研究成果可为变速恒频水轮机的设计和工程应用提供依据和参考。

基于mRMR-GRU的变速恒频风电机组图像识别算法

为了精准识别变速恒频风电机组的运行状态,提出基于mRMR-GRU的变速恒频风电机组图像识别算法。通过分析变速恒频风电机组机械动态结构,获取整体变速恒频风电机组运行的重要控制部分;基于物联网技术,集成智能终端传感设备在特定结构中采集变速恒频风电机组图像;分析风电机组特定结构,生成变速恒频风电机组原始图像;基于直方图均衡方法对变速恒频风电机组图像进行增强处理,输出高分辨率采集图像;基于mRMR算法,定义特征变量的互信息,获得最具代表性和相关性的特征子集;融合GRU单元与mRMR值生成mRMR-GRU算法,优化图像识别网络结构,输出的风机图像状态识别结果。实验结果表明:设计算法MAPE值为4.46,RMSE值为3.57,图像识别准确度最高值为0.98,能够有效调节图像的特征变量,有效识别变速恒频风电机组图像存在的异常情况,且具有明显的图像像素点均衡效果与图像增强识别效果。

热式风传感器的仿真优化设计

本文基于热温差原理,利用有限元分析软件ANSYS对热式风传感器在恒功率和温度平衡两种控制模式下的工况进行了模拟,分析了芯片结构的不同特征尺寸参数对传感器输出性能的影响规律。研究结果表明:传感器的输出分别随着芯片边长和厚度、加热元件长度的增加而增大,而当加热元件和测温元件之间距离增加时,输出减小。优化结构尺寸后的传感器在恒功率模式下,风向误差小于±2°,风速在0~15 m/s时,误差小于10%;温度平衡模式下,风向误差为±3°,风速有效测量范围可达0~20 m/s,误差小于5%,测量精度有所提高。

面向新能源基地的频率动态响应模型研究

为提升高渗透率新能源电力系统的频率响应特性认知和分析水平,运用小信号分析法对处在不同风速阶段的双馈异步风机模型进行元件等值,得到两输入、单输出的风机等值模型;在此基础上,提出一种可计及多种风速调频特性的改进频率响应模型,并将该模型与典型的系统频率响应模型相结合,建立考虑不同风况和风电机组(Wind Turbine Generator System,WTGS)不同调频特性的频率响应模型。本文采用该模型在改进的IEEE118节点系统中进行仿真分析,结果显示,该模型能够准确有效地分析高渗透率风电并网系统的频率响应特性。

基于时频分析的机组风速预测

文章提出了一种基于时频分析的机组风速预测算法,通过对气象数据的时域分析和频域分析,获得不同状态下风速的信号特征。预测不同特征下的风速信号来修正机组的风速,能更好地了解风能资源的分布和变化规律,以及风机的运行状态和性能,进而实现风机发电效能提升。

数控车床主轴变频调速传动控制系统设计

阐述数控车床主轴传动的转矩特性、数控车床主轴变频调速原理,探讨数控车床主轴变频调速传动控制设计方案,包括变频器选型设计、主轴传动控制设计、连接设计,从而提高数控机床控制效率。

子午水电站可逆水轮机组电气传动控制系统

介绍了子午水电站可逆水轮机组电气传动控制系统。基于四象限级联中压变频器,实现了机组发电工况下的变速恒频运行和抽水工况下的高效节能运行。同时,采用电气回路冗余设计、变频器功率单元快速旁路技术和中性点漂移技术,确保了机组的高效可靠运行。

粒子群优化PID的供水电机调速系统研究

针对叠压供水系统供水压力不稳定、控制效果时效性差的问题,提出了一种粒子群优化PID算法。结合粒子群算法与PID控制,根据供水压力展开粒子群优化PID参数算法程序,实时调整PID3个参数,并将其结果发送给变频器,实现电机平稳启动与调速,保证供水压力的稳定。仿真测试表明,该算法可实现对供水泵房电机的变频调速,有效解决了工频供水方式水压不稳定、控制效果时效性差的问题。

变频调速在煤气加压站恒压供气上的应用

煤气加压站作为煤气输送的关键环节,其恒压供气系统的稳定性、高效性和可靠性对供气效果和安全运行至关重要。为了满足不断增长的用气需求,提高能源利用效率,降低供气成本,变频调速技术作为一种先进的控制手段被广泛应用于煤气加压站的恒压供气系统中。变频调速技术通过调节压缩机的转速,实现了对供气量的精确控制,可以根据实际需求动态调整压缩机的运行状态,使其始终处于最佳工作状态,从而实现了能源的有效利用和供气的稳定性。然而,尽管变频调速技术具有诸多优势,但在实际应用中仍然存在一些挑战和问题,如操作复杂性、设备稳定性、维护成本和兼容性等。因此,有必要对变频调速技术在煤气加压站恒压供气系统中的应用进行深入研究和优化,以进一步提高系统的运行效率和性能,保障供气安全和稳定,促进煤气工业的健康发展和社会经济的可持续繁荣。

Circulating current suppression for ground tied variable frequency to constant frequency converter system in aircraft

This paper presents a solution to the circulating current fault of aircraft power supply.The DC-link type Variable Frequency to Constant Frequency(VFCF)converter system is the preferred scheme to feed the constant 400 Hz load in an aircraft with a variable frequency power supply.Due to the requirement of aircraft standards,both grounds of the rectification and inversion stage are tied to the metal frame of the aircraft.With such a tied ground,the DC bus voltage rises greatly,and a large circulating current appears in the casing as the ground,which leads to equipment failure and potential safety hazards.According to the existing methods of circulating current fault suppression,this paper analyzes the causes of the above faults and the harmonic components of circulating current and points out the limitations of the existing methods.Therefore,a Common-Mode(CM)choke-based method is proposed to provide a high impedance in the path of the CM circulating current.By doing so,the circulating current can be suppressed without the additional burden of the hardware and control algorithm,which is quite friendly for quality control of mass-production aircraft.Moreover,a simplified mathematic model of the VFCF converter system is derived to calculate the minimum inductance value reference of the CM choke,which saves the weight of passive devices to the greatest extent.Finally,simulation and experimental results are studied to verify the effectiveness of the proposed method.