Optimization of the Gas Generator in Composite Power System with Tip-Jet Rotor

The key and bottleneck of research on the tip-jet rotor compound helicopter lies in the power system. Computational Fluid Dynamics (CFD) was used to numerically simulate the gas generator and rotor inner passage of the tip-jet rotor composite power system, studying the effects of intake mode, inner cavity structure, propellant components, and injection amount on the characteristics of the composite power system. The results show that when a single high-temperature exhaust gas enters, the gas generator outlet fluid is uneven and asymmetric;when two-way high-temperature exhaust gas enters, the outlet temperature of the gas generator with a tilted inlet is more uniform than that with a vertical inlet;adding an inner cavity improves the temperature and velocity distribution of the gas generator's internal flow field;increasing the energy of the propellant is beneficial for improving the available moment.

GENERATOR VIBRATION FAULT DIAGNOSIS METHOD BASED ON ROTOR VIBRATION AND STATOR WINDING PARALLEL BRANCHES CIRCULATING CURRENT CHARACTERISTICS

Rotor vibration characteristics are first analyzed, which are that the rotor vibration of fundamental frequency will increase due to rotor winding inter-turn short circuit fault, air-gap dynamic eccentricity fault, or imbalance fault, and the vibration of the second frequency will increase when the air-gap static eccentricity fault occurs. Next, the characteristics of the stator winding parallel branches circulating current are analyzed, which are that the second harmonics circulating current will increase when the rotor winding inter-turn short circuit fault occurs, and the fundamental circulating current will increase when the air-gap eccentricity fault occurs, neither being strongly affected by the imbalance fault. Considering the differences of the rotor vibration and circulating current characteristics caused by different rotor faults, a method of generator vibration fault diagnosis, based on rotor vibration and circulating current characteristics, is developed. Finally, the rotor vibration and circulating current of a type SDF-9 generator is measured in the laboratory to verify the theoretical analysis presented above.

Real-Time Monitoring System for Rotor Temperature of a Large Turbogenerator Based on SmartMesh IP Wireless Network Communication Technology

In this study,a real-time rotor temperature monitoring system for large turbogenerators using SmartMesh IP wireless network communication technology was designed and tested.The system is capable of providing comprehensive,accurate,continuous,and reliable real-time temperature monitoring for turbogenerators.Additionally,it has demonstrated satisfactory results in a real-time monitoring test of the rotor temperature of various famous large-scale turbogenerators and giant nuclear power half-speed turbogenerators designed and manufactured in China.The development and application of this wireless temperature measurement system would aid in improving the intelligent operation quality,safety,and stability of China’s large turbine generators and even the entire power system.

A novel transient rotor current control scheme of a doubly-fed induction generator equipped with superconducting magnetic energy storage for voltage and frequency support

A novel transient rotor current control scheme is proposed in this paper for a doubly-fed induction generator（DFIG）equipped with a superconducting magnetic energy storage（SMES） device to enhance its transient voltage and frequency support capacity during grid faults. The SMES connected to the DC-link capacitor of the DFIG is controlled to regulate the transient dc-link voltage so that the whole capacity of the grid side converter（GSC） is dedicated to injecting reactive power to the grid for the transient voltage support. However, the rotor-side converter（RSC） has different control tasks for different periods of the grid fault. Firstly, for Period I, the RSC injects the demagnetizing current to ensure the controllability of the rotor voltage. Then, since the dc stator flux degenerates rapidly in Period II, the required demagnetizing current is low in Period II and the RSC uses the spare capacity to additionally generate the reactive（priority） and active current so that the transient voltage capability is corroborated and the DFIG also positively responds to the system frequency dynamic at the earliest time. Finally, a small amount of demagnetizing current is provided after the fault clearance. Most of the RSC capacity is used to inject the active current to further support the frequency recovery of the system. Simulations are carried out on a simple power system with a wind farm. Comparisons with other commonly used control methods are performed to validate the proposed control method.

Fault Diagnosis Based on ANN for Turn-to-Turn Short Circuit of Synchronous Generator Rotor Windings

Rotor winding turn-to-turn short circuit is a common electrical fault in steam turbines. When turn-to-turn short circuit fault happens to rotor winding of the generator, the generator terminal parameters will change. According to these parameters, the conditions of the rotor winding can be reflected. However, it is hard to express the relations between fault information and generator terminal parameters in accurate mathematical formula. The satisfactory results in fault diagnosis can be obtained by the application of neural network. In general, the information about the severity level of the generator faults can be acquired directly when the faulty samples are found in the training samples of neural network. However, the faulty samples are difficult to acquire in practice. In this paper, the relations among active power, reactive power and excitation current are discovered by analyzing the generator mmf with terminal voltage constant. Depending on these relations, a novel diagnosis method of generator rotor winding turn-to-turn short circuit fault is proposed by using ANN method to obtain the fault samples directly, without destructive tests.

Optimization of Rotor Assembly Process of Rotor Initial Unbalance of an Aeroengine Gas Generator

The rotor initial unbalance of an aeroengine gas generator of turboshaft engine seriously affects rotor assembly process.To reasonably optimize rotor assembly process,the effect analyses of rotor initial unbalance of single disc and combined discs on rotor dynamic characteristics are firstly implemented in respect of the dispersity of rotor initial unbalance.It is found that the most important factors contributing to rotor vibration are the unbalances of the first stage compressor disc and the second stage turbine disc.However,reducing the mass of two discs conflicts with the control of the whole gas generator rotor balance resulting from the unbalance increase of single components.Thus,we further analyze the key control factors of affecting rotor initial unbalance,and give the strict control measures of centrifugal impeller runout in the assembly process by adjusting the angle of central tie rod axis.The purpose of this measures to make the assembly process simpler and more effective for timely controlling rotor initial unbalance.The efforts of this study validate that the proposed method is workable for the rotor tightened by a central tie rod and possesses the significant meaning of practical application in engineering.

Dynamics in large generators due to oval rotor and triangular stator shape

Earlier measurements in large synchronous generators indicate the existence of complex whirling motion, and also deviations of shape in both the rotor and the stator. These non-symmetric geometries produce an attraction force between the rotor and the stator,called unbalanced magnetic pull（UMP）.The target of this paper is to analyse responses due to certain deviations of shape in the rotor and the stator.In particular,the perturbation on the rotor is considered to be of oval character,and the perturbations of the stator are considered triangular.By numerical and analytical methods it is concluded for which generator parameters harmful conditions,such as complicated whirling motion and high amplitudes,will occur.During maintenance of hydro power generators the shapes of the rotor and stator are frequently measured.The results from this paper can be used to evaluate such measurements and to explain the existence of complex whirling motion.

Rotor Vibratory Load Prediction Based on Generalized Forces

Three rigid-body-motion DOFs are introduced for the motion of the flap, laghinge and pitch bearing. The rotor blade is discretized using a five-nodes, 15 DOFs beam finiteelement. The dynamic coupling effect between the rigid motion of the blade and the nonlinear elasticdeflections is taken into account. Utilizing the constitutive law of the curvilinear coordinatesystem, the typical moderate deflection beam theory is reformulated. In addition, the Leishman andBeddoes unsteady and dynamic stall model is incorporated and the inflow is evaluated with the freewake analysis. The derived nonlinear ordinary differential equations with time - dependentcoefficients of the rotor blade are given in the sense of the generalized forces. The sectionalloads of the blade and the equations of motion are solved simultaneously in the physical space. Theblade vibratory loads predicted by present analysis show generally fair a-greement with the flighttest data of the SA349/2 Gazelle helicopter.

ZERO MODE NATURAL FREQUENCY AND NONLINEAR VIBRATION OF COUPLED LATERAL AND TORSION OF A LARGE TURBINE GENERATOR

Zero mode natural frequency (ZMNF) is found during experiments. The ZMNF andvibrations resulted by it are studied. First, calculating method of the ZMNF excited byelectromagnetic in vibrational system of coupled mechanics and electrics are given from the view ofmagnetic energy. Laws that the ZMNF varies with active power and exciting current are obtained andare verified by experiments. Then, coupled lateral and torsional vibration of rotor shaft system isstudied by considering rest eccentricity, rotating eccentricity and swing eccentricity. UsingLargrange-Maxwell equation when three phases are asymmetric derives differential equation of thecoupled vibration. With energy method of nonlinear vibration, amplitude-frequency characteristics ofresonance are studied when rotating speed of rotor equals to ZMNF. The results show that ZMNF willoccur in turbine generators by the action of electromagnetic. Because ZMNF varies withelectromagnetic parameters, resonance can occur when exciting frequency of the rotor speed is fixedwhereas exciting current change. And also find that a generator is in the state of large amplitudein rated exciting current.

Eco-Friendly Selection of Diesel Generator Based on Genset-Synchro Technology for Off-Grid Remote Area Application in the North of Quebec

For most of their energy requirements, greater part of remote communities and small islands around the world rely on imported fossil fuels. The economical cost of energy is therefore very high not only due to inherent cost of fuel, but also due to transportation and due to maintenance costs. One solution for saving fuel in a diesel generator is to allow the engine to operate directly in relation to the request for electrical load at variable speeds. Genset-Synchro Technology has developed an innovative variable speed?generator technology (patent pending) that allows applications where power demand varies widely to benefit from the new technology that maintains constant voltage and frequency while adjusting the generator stator speed to power demand. This paper will present an innovative approach for optimizing the energy production based from the fact that the structure that contains the stator windings of the generator is mounted on roller bearings, which allows its free rotation around the axis of the rotor, consequently stopping the stator structure from being static and aims to minimize the unit cost of electricity. Case study on application in remote area in the north of Quebec is described. A saving of 7%?-?9% on fuel consumption and greenhouse gas (GHG) under low winter ambient temperatures has been registered.

Robust Position Observer for Sensorless Direct Voltage Control of Stand-Alone Ship Shaft Brushless Doubly-Fed Induction Generators

The aim of this paper is to investigate an adaptive sensorless direct voltage control(DVC)strategy for the stand-alone ship shaft brushless doubly-fed induction generators(BDFIGs).The proposed new rotor position observer using the space vector flux relations of BDFIG may achieve the desired voltage control of the power winding(PW)in terms of magnitude and frequency,without any speed/position sensors.The proposed algorithm does not require any additional observers for obtaining the generator speed.The proposed technique can directly achieve the desired DVC based on the estimated rotor position,which may reduce the overall system cost.The stability analysis of the proposed observer is investigated and confirmed with the concept of quadratic Lyapunov function and using the multi-model representation.In addition,the sensitivity analysis of the presented method is confirmed under different issues of parameter uncertainties.Comprehensive results from both simulation and experiments are realized with a prototype wound-rotor BDFIG,which demonstrate the capability and efficacy of the proposed sensorless DVC strategy with good transient behavior under different operating conditions.Furthermore,the analysis confirms the robustness of the proposed observer via the machine parameter changes.

Experimental Study on Aerodynamic Characteristics of the Model Wind Rotor System and on Characterization of A Wind Generation System

In order to investigate the aerodynamic characteristics of 6-MW wind turbine, experimental study on the aerodynamic characteristics of the model rotor system and on characterization of a wind generation system is carried out. In the test, a thrust-matched rotor system and a geometry-matched rotor system, which utilize redesigned thrustmatched and original geometry-matched blades, respectively, are applied. The 6-MW wind turbine system is introduced briefly. The proper scaling laws for model tests are established in the paper, which are then implemented in the construction of a model wind turbine with optimally designed blades. And the parameters of the model are provided. The aerodynamic characteristics of the proposed 6-MW wind rotor system are explored by testing a 1:65.3 scale model at the State Key Laboratory of Ocean Engineering at Shanghai Jiao Tong University. Before carrying out the wind rotor system test, the turbulence intensity and spatial uniformity of the wind generation system are tested and results demonstrate that the characterization of the wind generation system is satisfied and the average turbulence intensity of less than 10% within the wind rotor plane is proved in the test. And then, the aerodynamic characteristics of 6-MW wind rotor system are investigated. The response characteristic differences between the thrust-matched rotor system and the geometry-matched rotor system are presented. Results indicate that the aerodynamic characteristics of 6-MW wind rotor with the thrust-matched rotor system are satisfied. The conclusion is that the thrust-matched rotor system can better reflect the characteristics of the prototype wind turbine. A set of model test method is proposed in the work and preparations for further model basin test of the 6-MW SPAR-type floating offshore wind turbine system are made.

A General Calculating Method of Rotor’s Torsional Stiffness Based on Stiffness Influence Coefficient

In order to develop a general calculating rotor’s torsional stiffness based on stiffness influence coefficient for different rotor assembling, the calculation method of the torsional stiffness influence coefficient of equal thickness disc is researched in this paper at first. Then the torsional stiffness influence coefficient λ of equal thickness disc is fit to a binary curved face and a calculation equation is obtained based on a large quantity of calculating data, which lays the foundation for research on a general calculating method of rotor torsional stiffness. Thirdly a simplified calculation method for equivalent stiffness diameter of stepped equal thickness disc and cone disc in the steam turbine generators is suggested. Finally a general calculating program for calculating rotor’s torsional vibration features is developed, and the torsional vibration features of a verity of steam turbine rotors are calculated for verification. The calculating results show that stiffness influence coefficient λ of equal-thickness disc depends on parameters of B and H, as well as the stiffness influence coefficient λ;and discs with complex structure can be simplified to equal-thickness discs with little error by using the method suggested in this paper;error can be controlled within 1% when equivalent diameter of stiffness is calculated by this method.

The evaluation of the safety of shaft system of large turbine generator set

1.IntroductionWith the increase of the capacity of the turbine generator set,the safety of the shaft system of the set(including the exciter)isthreatened for the following three reasons:1.The length of the shaft system increases.The length of theshaft system is 15 m for a 50 MW set,32-40 m for a 300 MW set and90 m for a 900 MW nuclear power set.The increased number of theconcentrated masses leads to the increase of both the number of

基于改进自适应陷波的双馈风电场时变次同步振荡抑制策略

双馈风电场经串补电容并网时,可能引发次同步控制相互作用(subsynchronous control interaction,SSCI),严重威胁系统安全稳定运行。通过在风机控制器中引入陷波器可有效阻断SSCI,然而固定参数陷波器难以适应实际系统中次同步振荡表现出的频率大范围时变特征。为解决这一问题,该文提出一种基于改进自适应陷波(adaptive notch filter,ANF)的双馈风电场时变次同步振荡抑制策略。首先,分析ANF安装于风机转子侧变流器(rotor-side converter,RSC)不同位置时对次同步振荡分量的阻断效果,确定ANF的最佳安装位置;其次,基于紧缩技术近似投影子空间跟踪算法(projection approximation subspace tracking based on the deflation technique,PASTd)在线获取次同步振荡信息,提出总体控制架构,设计基于量测数据辨识的ANF中心频率更新策略;最终,在考虑风速、风机台数、无功出力、电网拓扑变化等多种影响因素的情况下,验证控制策略对频率时变次同步振荡的抑制效果。与现有方法相比,所提控制策略不依赖于系统的准确数学模型,且具备较强的鲁棒性和适应性。

轴径向静态偏心故障下外转子永磁发电机电磁转矩特性分析

对外转子永磁发电机轴径向静态偏心故障下的电磁转矩特性进行了理论解析、仿真计算和实验验证。首先,在考虑齿槽效应影响条件下,引入磁导修正系数ε(θ),推导出轴径向静态偏心前后气隙磁密表达式,并考虑绕组分布情况,构建一种新型的永磁发电机轴径向静态偏心故障下相电流数学模型,在此基础上得到轴径向偏心下电磁转矩解析表达式。其次,通过有限元仿真计算得到外转子永磁发电机轴径向静态偏心下的电磁转矩波动特性。最后,在一台外转子永磁发电机上通过故障模拟实验实例印证了解析分析和仿真计算结果。结果表明:相较于正常情况,径向偏心时,电磁转矩以直流、二倍频、四倍频成分为主,随着偏心程度的加剧,电磁转矩的直流、二倍频、四倍频成分幅值将随着增大;轴向偏心时,电磁转矩谐波成分不变,随着偏心程度的加剧,各谐波成分幅值将随着减小。对外转子永磁发电机气隙偏心故障分析的一个重要补充,对此类问题的现场检测和鉴定具有参考价值。

基于SVD-CWT和CNN的水轮发电机转子故障识别

水轮发电机转子振动故障识别是水电站运维的重难点问题,为此提出一种基于转子振动信号的故障识别方法。首先针对发电机转子的非平稳和非线性振动信号,采用奇异值分解(SVD)并结合能量差分谱理论进行降噪预处理;对预处理数据使用连续小波变换(CWT)转换为时频图并形成图像数据集;然后将该图像数据集作为卷积神经网络(CNN)输入,通过CNN多层池化及卷积形成分布式故障特征表达,最终实现发电机转子故障模式识别和分类。经实验验证,该方法准确率达到99.5%以上,能有效识别出发电机转子的故障类型。

倾斜偏心对同步发电机转子力学特性的影响

气隙偏心是一种常见的发电机机械故障。已有研究主要关注正常和轴向气隙均匀偏心对转子受载和振动特性的影响,较少关注轴向气隙非均匀偏心,即转子倾斜偏心。作为补充,全面分析转子倾斜偏心状态下故障程度差异对同步发电机转子力学特性的影响。其中,转子力学特性包括转子不平衡磁拉力激励特性和振动特性。以一台5kVA的两极故障模拟发电机为研究对象,分别进行理论分析、有限元仿真计算和实验验证。结果表明:正常情况下转子不平衡磁拉力为零,转子振动频率以常规基频和定子传递的各偶次谐波为主。在转子发生倾斜偏心故障后,转子不平衡磁拉力/振动以二次谐波为主。随着偏心程度增加,转子不平衡磁拉力/振动的二次谐波幅值将增大。此外,转子不平衡磁拉力沿轴向非均匀分布,在气隙越小的位置不平衡磁拉力越大。

汽轮发电机转子匝间短路对定子热响应特性的影响

本文分析了汽轮发电机转子匝间短路故障前后定子热响应特性,不仅考虑转子匝间短路引起电压下降对发电机强励动作的影响,还研究了热分布不平衡而引起的定子力学响应。首先推导了正常情况和转子匝间短路故障后加强励磁电流下的气隙磁通密度,得到了铁心损耗和绕组铜耗的解析表达式;然后建立了发电机故障前后的三维有限元仿真模型,对不同短路程度故障下的铁心损耗、绕组铜耗与定子温度进行了求解计算;最后实测了CS-5型故障模拟发电机在正常运行和不同短路程度故障下的定子温度,实验结果与理论分析、有限元仿真结果基本一致。结果表明,转子匝间短路故障后由于励磁电流的增强,发电机铁心损耗和绕组铜耗均会增加,定子温度明显上升,并且随着短路程度的增加而加剧;定子端面边缘位置的变形和应力幅值最大并且为热响应下的危险位置。

基于定子电流法的绕线转子无刷双馈发电机偏心故障研究

绕线转子无刷双馈电机在船舶轴带发电以及风力发电等领域中具有良好的应用前景。转子偏心是一种常见的机械故障,威胁着现代化工业体系的稳定运转,因此实现其状态检测和故障诊断非常关键。由于无刷双馈电机具有特殊的定、转子绕组结构以及复杂的气隙磁场,因此传统的故障检测方法无法直接用于该类电机。该文通过定子电流法提取了功率绕组电流的特征频率分量作为故障指标,实现对静偏心、动偏心以及混合偏心的无创诊断。建立故障电机的时步有限元模型,并通过详细的故障机理分析,得出不同类型的偏心故障可能导致的特征频率信号。最后,以一台2/4对极无刷双馈电机为例,并通过有限元仿真、样机试验验证解析法的结论,为绕线转子无刷双馈电机偏心故障的精准检测提供了理论依据。