基于自适应滑模观测器的高铁牵引系统单相三电平整流器开路故障诊断

为了提升高速列车牵引系统的稳定性和可靠性,本文针对其单相三电平整流器,提出了一种基于自适应滑模观测器的开关管开路故障诊断方法.本文首先建立了单相三电平整流器开路故障下的状态空间模型,然后设计了收敛速度快且显著抑制高频抖振的自适应滑模观测器准确估计网侧电流,其次利用整流器网侧电流与观测器输出电流提出了基于电流绝对值均方根的开关管开路故障检测方法,在此基础上采用电流残差构造初次故障定位量进行开关管初步定位,最后利用开路故障开关函数建立故障状态下的自适应滑模观测器实现故障开关管精确定位.本文提出的方法能够实现单相三电平整流器所有开关管故障检测与定位,诊断速度快,鲁棒性强,且不需要额外注入脉冲控制信号.实验结果验证了本文所提诊断方法的准确性和鲁棒性.     

双馈风力发电机状态监测系统软件设计

采用双馈风力发电机状态监测系统可及时发现并跟踪风电机组主要部件的机械和电气故障,有效降低机组的运行维护成本,保证风电机组的安全稳定运行.软件采用模块化设计思想,主要功能包括管理、诊断、监测、查询、数据存储、数据备份等.通过对振动、电流、电压、温度等参量进行分析,该软件实现了诊断发电机定子和转子匝间短路、相间短路、相对地短路、轴承故障的功能.将该系统试用于某风电场1.5 MW双馈发电机组上,结果表明其可用于监测和诊断双馈风力发电机.     

基于新型转子撬棒的双馈风电机组低电压穿越技术

针对目前双馈风力发电系统低电压穿越方案所存在的问题,尤其是转子侧投入撬棒后在穿越过程中的一些不足,提出了一种新型的阻容式转子撬棒以改善双馈风力机组的低电压穿越能力。在分析了双馈风力发电机故障期间投入撬棒后特点的基础上,结合其对应的等效电路,推导出双馈风力发电机定子侧与转子侧的无功功率表达式。对无功功率表达式定性分析后,得出提高低电压穿越能力的方案,并以此设计出一种不同于传统撬棒的新型转子撬棒,即阻容式转子撬棒。利用MATLAB/simulink搭建仿真模型进行验证,仿真结果表明:新型阻容式转子撬棒不仅可以在定子侧加快故障电压的恢复,而且可以限制转子侧过电流,抑制因撬棒的投切而对机侧变流器的暂态冲击,最终实现了有效提高双馈风力发电系统低电压穿越能力的目的。     

双馈感应风力发电机实现LVRT控制策略研究

根据最新的风电场接入电网规定,在电网发生故障情况下风力发电机组应能保持与电网的连接。电网电压跌落是电网故障常见的形式之一,所以如何提高双馈感应风力发电机组低电压穿越能力成为了当今风电技术的研究热点。本文根据低电压穿越技术的基本原则,通过改进转子侧的控制策略和增加保护电路的方案来实现低电压穿越技术。通过仿真研究表明,改进的控制策略可以有效的抑制转子侧过电流,能够有效的提高双馈感应风力发电机在故障期间的低电压穿越能力。     

无刷双馈发电机及其控制策略的仿真研究

给出了无刷双馈发电机的转子机械速dq0数学模型和定子同步速MT数学模型;提出了一种无刷双馈发电机空载并网控制策略,该策略根据定子同步坐标系下无刷双馈发电机有功功率、无功功率给定值,最终得出控制侧定子绕组的电压给定值,将该值进行2r/3s变换后输入SVPWM调制模块,得到的PWM信号用于控制机侧变流器开关管的通断,从而产生定子控制绕组所需的电压、电流;在Matlab/Simulink环境下搭建了无刷双馈发电机及其控制仿真模型,并对无刷双馈发电机在空载、并网状态下的动态性能进行了仿真研究。仿真结果验证了所搭建模型及空载并网控制策略的正确性、有效性。     

TwinCAT PLC全功率风力发电机组试验系统的研究

为保障出厂的风电机组能够达到质量标准,利用原动机、变频器等外围设备和1.5 MW变桨双馈风力发电机组(除叶片和塔筒)搭建了试验平台。该平台采用TwinCAT PLC软件检测风电机组在全功率和全工况运行时的功率曲线,同时在模拟的故障状态下,检测电控系统、发电机和变流器基本保护功能。试验平台能够对风电机组的设计、制造、装配质量等环节进行检验。结果表明检测通过的风电机组达到了出厂质量标准。     

变速恒频双馈风力发电系统网侧变流器控制策略研究

变速恒频双馈风力发电系统通常采用磁链定向、转子磁链定向和气隙磁场定向进行控制,这些控制系统的结构设计复杂,控制精度不高。为了进一步提高风力发电系统的控制效果,论文对变速恒频双馈风力发电系统的双P W M变流器进行了详细的分析,针对网侧变流器建立了数学模型,对网侧变流器的控制策略进行了研究,并采用电压、电流双闭环控制策略对系统中的网侧变流器进行控制。仿真结果显示,双闭环控制策略系统经过短暂的振荡之后能够快速实现状态的转变,达到预期效果。     

并网双馈感应风电机短路故障特性的仿真研究

研究并网双馈感应风电机短路故障特性.由于变流器控制系统对故障特性的影响不可忽视,所以为了更为准确地分析诊断系统故障以保证系统的安全运行,从DFIG短路故障时的暂态过程出发,在考虑转子电流动态特性的情况下提出了DFIG对称短路电流的动态表达式,进而对短路故障电流的特性进行了分析,并利用PSCAD/EMTDC平台进行了仿真分析.仿真结果表明了DFIG变流器控制系统对短路故障特性的影响,为风电系统的故障分析诊断提供了一定的依据.     

具有输出时延的网络控制系统故障检测

考虑一类具有长时延的网络控制系统,假定其传感器到控制器之间存在输出时延,对其进行故障检测研究.建立具有时延补偿功能的故障观测器,得到状态估计误差方程.基于离散切换系统理论,将观测器系统的稳定条件归结为一个线性矩阵不等式.当系统正常时,只要给定的矩阵不等式条件成立,该观测器系统就是渐近稳定的.当系统发生故障时,观测器残差能够迅速发生跳变,从而检测出故障的发生.仿真示例验证了方法的有效性.     

一种基于全维和降维观测器的故障检测和重构方法

针对不确定性非线性系统,讨论基于观测器的执行器故障的检测和重构方法.首先,通过设计滑模全维观测器,产生对干扰具有鲁棒性、对故障具有敏感性的残差,来达到故障检测的目的;然后,设计能直接消去干扰和故障影响的降维观测器来达到状态渐近收敛估计,并在此基础上,提出故障重构方法;基于微分方程的数值解方法和函数微分的数值解方法,给出一种故障重构的数值解方法;最后,对一个实际模型进行仿真,结果表明了该方法的实用性.     

理想电网条件下双馈风力发电系统低电压穿越技术的控制策略研究

随着风电在电网所占比例的不断增大,提高风机在故障条件下的不间断运行能力越来越重要。通过分析交流励磁变速恒频双馈风机的运行特点,建立双馈风力发电系统的并网数学模型;针对电网电压小幅对称跌落,在不增加硬件成本的基础上,改进传统双馈发电机矢量控制策略,加入前馈补偿项来抑制电压小幅跌落时转子中的过电流,提高双馈风力发电系统的低压穿越能力。在MATLAB/SIMULINK中验证控制策略的合理性,为以后深入研究双馈风力发电系统提供了基础。     

Intelligent Open Switch Fault Detection for Power Converter in Wind Energy System

This paper proposes a simple and fast fuzzy logic-based open switch fault detection method for rotor side converter (RSC) in doubly fed induction generator (DFIG) wind turbine system. In the proposed scheme, only the mean values of the three-phase rotor currents are used to identify the power switch in which the open-circuit fault has occurred.

The wind energy conversion system model developed for the design and evaluation of the proposed fault detection technique including three principal controls. the first control ensure the regulation of the electromagnetic torque and the reactive stator power (named Rotor Side Converter (RSC) control), the second regulates the DC-link voltage at the desired level (named Grid Side Converter (GSC) control) and in order to achieve maximum power at any wind speed condition a maximum power point tracking (MPPT) control strategy has been used. The simulation model was developed in MATLAB/Simulink environment. The results show that the proposed fault detection scheme is able to rapidly and effectively identify open switch faults among other fault types in a time less than one period.     

双馈风力发电机无速度传感器控制研究

间接利用定子、转子电流间的比例关系,分析转子电流和转子位置观测之间的关系,提出了一种基于PQ 功率转子位置观测法的DFIG 矢量控制策略,这种控制策略克服了其他速度观测方式在同步速运行时观测不准的缺陷,具有较宽广的运行范围,能够取得与有速度传感器控制相似的稳态性能。最后构建了DFIG 仿真与实验平台,对所述无位置传感器控制策略进行了仿真与实验验证。仿真结果和试验结果证明了这个控制方法的正确性与有效性。     

双PWM直驱同步风力发电机最大风能捕获

以直驱同步风力发电机组为研究对象,为了提高发电机的系统的效率,降低电机的损耗,采用双PWM变流器拓扑结构,提出了一种最大风能捕获（MPPT）的控制方式。不需要风速信号、风机转速及与风力机系统参数有关的最大功率运行表格,仅需对输出功率进行跟踪计算,使得能达到捕获最大风能的控制效果。采用PSCAD／EMTDC软件进行仿真,仿真结果验证了控制方法的有效性。     

An improved model predictive control of low voltage ride through in a permanent magnet synchronous generator in wind turbine systems

This research investigates a wind energy conversion system based on a permanent magnet synchronous generator (PMSG). In addition, a model predictive control (MPC) is proposed for the PMSG in normal and fault conditions. The most efficient mode of the control algorithm is found for maximum power point tracking in normal conditions and fast dynamic response in fault conditions following the selection of the optimum voltage vector. This method prevents a sudden increase in the DC‐link voltage by storing the active power in the generator rotor inertia. Moreover, during the low voltage, the grid code adoption of the reactive current is injected into the grid side. The performance of the proposed control scheme is evaluated for a wind power generator using MATLAB software. The simulation results demonstrate that the proposed method can safeguard the DC‐link during the fault.     

基于观测器的发电机功角与故障估计

针对发电机功角与故障估计这个问题,提出一种利用观测器的方法.该方法通过对系统数学模型进行状态变换,将数学模型分为含故障与不合故障两部分.对不合故障部分设计观测器,然后经过状态变换可以得到功角信息.在故障估计过程中,通过增广误差系统设计增广观测器可以得到故障的幅值.最后通过Matlab仿真分析,验证基于观测器功角与故障估计方法的有效性,结果表明该方法具有速度快、误差小的优点.     

A multiple observers and dynamic weighting ensembles scheme for diagnosing new class faults in wind turbines

This paper presents an incremental way to design the decision module of a diagnostic system by resorting to dynamic weighting ensembles of classifiers. The method is applied for sensor fault detection and isolation in a doubly fed induction generator for wind turbine application. Three sets of observers are combined to generate residuals that are robust to operating point changes. These signals are progressively fed into a dynamic weighting ensembles algorithm, called Learn⁺⁺.NC, for fault classification. The algorithm incrementally learns the residuals–faults relationships and dynamically classifies the faults including multiple new classes. It resorts to a dynamically weighted consult and vote mechanism to combine the outputs of the base-classifiers.     

Combination of model-based observer and support vector machines for fault detection of wind turbines

Support vector machines and a Kalman-like observer are used for fault detection and isolation in a variable speed horizontalaxis wind turbine composed of three blades and a full converter. The support vector approach is data-based and is therefore robust to process knowledge. It is based on structural risk minimization which enhances generalization even with small training data set and it allows for process nonlinearity by using flexible kernels. In this work, a radial basis function is used as the kernel. Different parts of the process are investigated including actuators and sensors faults. With duplicated sensors, sensor faults in blade pitch positions,generator and rotor speeds can be detected. Faults of type stuck measurements can be detected in 2 sampling periods. The detection time of offset/scaled measurements depends on the severity of the fault and on the process dynamics when the fault occurs. The converter torque actuator fault can be detected within 2 sampling periods. Faults in the actuators of the pitch systems represents a higher difficulty for fault detection which is due to the fact that such faults only affect the transitory state(which is very fast) but not the final stationary state. Therefore, two methods are considered and compared for fault detection and isolation of this fault: support vector machines and a Kalman-like observer. Advantages and disadvantages of each method are discussed. On one hand, support vector machines training of transitory states would require a big amount of data in different situations, but the fault detection and isolation results are robust to variations in the input/operating point. On the other hand, the observer is model-based, and therefore does not require training, and it allows identification of the fault level, which is interesting for fault reconfiguration. But the observability of the system is ensured under specific conditions, related to the dynamics of the inputs and outputs. The whole fault detection and isolation scheme is evaluated using a wind     

高速列车牵引整流器多类故障联合诊断方法

提出了一种高速列车牵引整流器多类故障联合诊断方法. 首先, 基于三电平牵引整流器开路故障分析, 建立整流器所有功率器件开路故障以及正常运行的状态空间模型并构建相应状态观测器. 然后, 基于正常状态观测器进行故障检测, 检测到故障后, 基于故障观测器区分功率器件开路故障和网侧电流传感器故障, 进而诊断出功率器件开路故障位置和网侧电流传感器故障类型. 实时仿真结果验证了本文方法的正确性和有效性.     

Sensorless adaptive output feedback control of wind energy systems with PMS generators

This paper addresses the problem of controlling wind energy conversion (WEC) systems involving permanent magnet synchronous generator (PMSG) fed by IGBT-based buck-to-buck rectifier–inverter. The prime control objective is to maximize wind energy extraction which cannot be achieved without letting the wind turbine rotor operate in variable-speed mode. Interestingly, the present study features the achievement of the above energetic goal without resorting to sensors of wind velocity, PMSG speed and load torque. To this end, an adaptive output-feedback control strategy devoid of any mechanical sensor is developed (called sensorless), based on the nonlinear model of the whole controlled system and only using electrical variables measurements. This control strategy involves: (i) a sensorless online reference-speed optimizer designed using the turbine power characteristic to meet the maximum power point tracking (MPPT) requirement; (ii) a nonlinear speed regulator designed by using the backstepping technique; (iii) a sensorless interconnected adaptive state observer providing online estimates of the rotor position as well as speed and load/turbine torque. The proposed output-feedback control strategy is backed by a formal analysis showing that all control objectives are actually achieved. Several simulations show that the control strategy enjoys additional robustness properties.