Parallel Correlative Study of the Heat Balance Test Process for Testing the Efficiency of Turbo-Generators

In order to prolong the life span of a turbo-generator plant and sustain its performance at high efficiency, it is subjected periodically to regular test to monitor the operational profile and efficiency of power conversion from mechanical energy to electrical energy. Analysis of these test data serves as a measure to indicate deviation from normal operation profile and deterioration of plant performance. This present work implemented the heat balance tests process to three turb- generator units in order to assess the harmony, consistency, and accuracy of results to establish parallel correlation for the test process. The test process involves carrying out a heat balance for the turbo-generators at 50%, 75% and 100% load respectively through the determination of the heat losses through the hydrogen coolers, bearing oil, seal oil and radiation and convention to the atmosphere. Some important results were presented in the paper.

Investigation and recommendation on allowable operating duration of large-sized turbine-generator unit under abnormal frequency

1.IntroductionWith the increasing of turbo-generator (TG) capacity,the limi-tation on the abnormal frequency operation is growing more restric-tive.In order to ensure the safety operation of certain TG unit,splitingdevice which isolates the generating unit from the system is em-ployed when the system frequency is declined to a certain extent.However,during the degradation of frequency,to isolate the large-sized TG unit from the power system will cause the system fre-quency to further decline.Hence,how to use the low frequency split-ting protection properly and how to coordinate the operation of underfrequency load shedding (UFLS) with under frequency generatorsplitting (UFGS) are significant for securing the safety operation

Adequate Closed Form Wave Solutions to the Generalized KdV Equation in Mathematical Physics

In this paper, we consider the generalized Korteweg-de-Vries (KdV) equations which are remarkable models of the water waves mechanics, the shallow water waves, the quantum mechanics, the ion acoustic waves in plasma, the electro-hydro-dynamical model for local electric field, signal processing waves through optical fibers, etc. We determine the useful and further general exact traveling wave solutions of the above mentioned NLDEs by applying the exp(−τ(ξ))-expansion method by aid of traveling wave transformations. Furthermore, we explain the physical significance of the obtained solutions of its definite values of the involved parameters with graphic representations in order to know the physical phenomena. Finally, we show that the exp(−τ(ξ))-expansion method is convenient, powerful, straightforward and provide more general solutions and can be helping to examine vast amount of travelling wave solutions to the other different kinds of NLDEs.

Turbo码概率-代数联合解码算法

Turbo码采用修正的BAHLetal.算法实现解码 .这是一种基于软值的概率迭代解码算法 .本文在保持Turbo码迭代软解码算法优点的基础上 ,充分利用Turbo码编码器结构这一确知条件 ,结合代数解码原理 ,提出了一种Turbo码概率 代数联合解码算法 .该算法结合了概率解码和代数解码的优点 ,又有效避免了误差传播的发生 ,使Turbo码的纠错性能在原经典算法的基础上得到进一步的提高 .该算法不仅为降低Turbo码的比特误码率和误差地板值提供了一种新的研究途径 ,而且因其更好的纠错性能而具有十分明显的实用价值 .仿真实验结果显示 ,在比特误码率(BER)为 10 -3 ～ 10 -4时 ,与经典Turbo码解码算法相比 ,采用该算法能获得 0 .

MIL-STD-188-110C波形的Turbo均衡技术应用研究

介绍了美军标MIL-STD-188-110C定义的短波波形,阐述了Turbo均衡原理并详细介绍了基于MMSE的线性Turbo均衡算法,对MIL-STD-188-110C中定义的波形5在12 kHz和24 kHz带宽的情况下应用Turbo均衡进行仿真,验证Turbo均衡技术在宽带短波波形中的应用效果。

级联的Turbo码和差分M-PSK调制的时-空分组码

时 -空分组码 (Space- Tim e Block Code)提供了一个有效的方法能完全利用发送分集和接收分集抗无线衰落。为了得到显著的编码增益 ,时 -空分组码必须和信道编码级联。本文提出了级联的 Tur-bo码和差分 M- PSK调制的时 -空分组码传输系统。描述了该系统实际上是一个串联的 turbo码结构并推导了 SISO(Soft Input Soft Output)迭代译码。计算机模拟结果表明 :在误码率为 10 - 4 ～ 10 - 5 时 4- DP-SK参与迭代和 4- DPSK不参与迭代相比可以获得 1d B的增益 ,而在误帧率为 10 - 4时 ,4- DPSK参与迭代获得的增益大于 1d B.

Turbo flow在线净化-超高效液相色谱-串联质谱法检测水果中5种咪唑类农药残留

建立了 Turbo flow（TF）在线净化-超高效液相色谱-串联质谱同时检测水果中吡咪唑、咪唑烟酸、咪鲜胺、咪唑嗪和咪唑菌酮等5种咪唑类农药的方法。以饱和氯化钠溶液溶解样品，乙腈提取，蒸干，乙腈-水（1∶1，v / v）溶液定容后进入 Turbo flow-超高效液相色谱-串联质谱系统分析，外标法定量。对影响 TF 净化的条件如 TF 色谱柱、流动相、洗脱溶液、洗脱速率等进行了优化。在优化的实验条件下，以 Turbo flow C18（50 mm×1.0 mm）为净化柱，Hypersil GOLD aQ（100 mm×2.1 mm）为分析柱，乙腈和5 mmol / L 甲酸铵溶液（含0.1％（ v / v）甲酸）为流动相进行梯度洗脱，在电喷雾正离子选择反应监测模式下进行检测。结果表明，各目标化合物在0.0075~0.75 mg / L范围内线性关系良好（相关系数均大于0.99），定量限为0.005 mg / kg。对实际样品分别加标0.005、0.01、0.05和0.5 mg / kg，回收率为71.2％~122.4％，相对标准偏差（RSD）为0.5％~8.9％。该方法简便、快速，结果准确可靠，适用于水果中5种咪唑类农药残留的检测。

Exact solutions for unsteady unidirectional flows of a generalized second-order fluid through a rectangular conduit

The exact solutions are obtained for unsteady unidirectional flows of a generalized second-order fluid through a rectangular conduit. The fractional calculus in the constitutive relationship of a non-Newtonian fluid is introduced. We construct the solutions by means of Fourier transform and the discrete Laplace transform of the sequential derivatives and the double finite Fourier transform. The solutions for Newtonian fluid between two infinite parallel plates appear as limiting cases of our solutions.

Analytical and Traveling Wave Solutions to the Fifth Order Standard Sawada-Kotera Equation via the Generalized exp(-Φ(ξ))-Expansion Method

In this article, we propose a generalized exp(-Φ(ξ))-expansion method and successfully implement it to find exact traveling wave solutions to the fifth order standard Sawada-Kotera (SK) equation. The exact traveling wave solutions are established in the form of trigonometric, hyperbolic, exponential and rational functions with some free parameters. It is shown that this method is standard, effective and easily applicable mathematical tool for solving nonlinear partial differential equations arises in the field of mathematical physics and engineering.

Parameter Self - Learning of Generalized Predictive Control Using BP Neural Network

This paper describes the self—adjustment of some tuning-knobs of the generalized predictive controller(GPC).A three feedforward neural network was utilized to on line learn two key tuning-knobs of GPC,and BP algorithm was used for the training of the linking-weights of the neural network.Hence it gets rid of the difficulty of choosing these tuning-knobs manually and provides easier condition for the wide applications of GPC on industrial plants.Simulation results illustrated the effectiveness of the method.

First 50 MVA turbo-type synchronous condenser with evaporative cooling of stator commissioned

Based on the successful operation of 1200 kW turbo-typemodel generator with separated evaporative cooling ofboth stator and rotor,a 50 MVA turbo-type synchronous condenserwith evaporative cooling stator was constructed and put into opera-tion on March 8,1991 at Xijiao Substation of Shanghai Power Bu-reau.This is the first one in the world that applied the evaporativecooling technique on turbo-generator in industrial scale.

Nondifferentiable Multiobjective Programming under Generalized d_I-G-Type I Invexity

To relax convexity assumptions imposed on the functions in theorems on sufficient conditions and duality,new concepts of generalized dI-G-type Ⅰ invexity were introduced for nondifferentiable multiobjective programming problems.Based upon these generalized invexity,G-Fritz-John （G-F-J） and G-Karnsh-Kuhn-Tucker （G-K-K-T） types sufficient optimality conditions were established for a feasible solution to be an efficient solution.Moreover,weak and strict duality results were derived for a G-Mond-Weir type dual under various types of generalized dI-G-type Ⅰ invexity assumptions.

Hydrocarbon-Generating Model of the Area Covered With Volcanic Rock

The distribution of Oil & gas fields shows their close relationship with the most active tectonic regions. This is not a coincidence but having a scientific reasons. The crustal active regions, refer to the places where the active natural earthquake, volcanic activities, underground water happened, and the areas of the leaking Off of natural gas to the surface of the crust. The magma of volcanic activities brings the organic "kitchen range body" hydrocarbon - generating model and inorganic genetic hydrocarbon to the regions covered by volcanic rock. Underground water brings a catalytic hydrocarbon generating model for organic matter, and the leaking - off of H2 and CO2 contributes a synthetic hydrocarbon - generating model. Volcanic activities bring the assemblage of Source, Reservoir and Seal formed by the sediments and magma the sedimentary basins, and the hydrocarbon - generating system with a "water - volcano" binary structure is formed. All these conditions are favorable and excellent for the formation of oil & gas fields. The distribution of AInerican oil & gas fields have very close relationship with the mines of Fe, Mn, Cr, Mo, W and V, deposits of Zn, Cu, V, Pb, Al and Hg, and the deposits of fluorite, sulfur, potassium salt, phosphate and halite, and the distribution of sulfate - chloride of river water. The reason why few oil & gas fields discovered in the regions covered by volcanic rock in western America maybe because of the view of "inconsistency between petroleum and volcano". Further more, It’s very difficult to carry out a geophysical exploration in such kinds of regions. This paper examined a few hydrocarbon - generating models (systems) mentioned above and came up with some flesh ideas on the exploration in the areas covered with volcanic rocks.

The Commutativity of a *-Ring with Generalized Left *-α-Derivation

In this paper, it is defined that left *-α-derivation, generalized left *-α-derivation and *-α-derivation, generalized *-α-derivation of a *-ring where α is a homomorphism. The results which proved for generalized left *-derivation of R in [1] are extended by using generalized left *-α-derivation. The commutativity of a *-ring with generalized left *-α-derivation is investigated and some results are given for generalized *-α-derivation.

基于广域测量的汽轮发电机励磁反步控制方法

由于汽轮发电机励磁反步控制过程中没有实时获取发电机的运行数据,致使电机励磁反步控制效果较差,为此提出基于广域测量的汽轮发电机励磁反步控制方法。通过广域测量系统的同步相量测量单元,实时采集汽轮发电机功角与电流等运行数据,将采集的运行数据变更成标幺值形式,根据该形式建立汽轮发电机励磁控制的数学模型,获取励磁反步控制变量,并结合反步法,设计汽轮发电机励磁反步控制器,通过径向基函数神经网络估计控制器内的扰动,完成控制器扰动补偿。实验结果表明:该方法可精准采集汽轮发电机运行参数,有效反步控制汽轮发电机励磁,令汽轮发电机功角与转子角速度等迅速恢复至稳定状态,具备较优的反步控制效果;应用该方法后,可确保电网运行稳定性,降低故障后电网切机量。

U型线圈检测发电机励磁绕组匝间短路性能分析

励磁绕组匝间短路故障在汽轮发电机中具有较高的发生率,对该故障进行灵敏、快速和可靠诊断可以防止故障恶化、降低故障查找成本。本文分析了励磁绕组匝间短路的磁场特征,介绍了U型检测线圈法检测励磁绕组匝间短路的基本原理,通过有限元仿真模拟汽轮发电机额定负载工况,在转子各槽设置不同程度匝间短路故障,获取安装于不同位置的U型线圈的感应电压,进一步提取电压谐波特征以及时域脉冲波形变化规律,比较了U型线圈处于不同位置的检测效果,为U型线圈的安装提供了可靠的数据支持。

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。

计及复杂换位结构的百万千瓦级汽轮发电机定子流固耦合传热研究

百万千瓦级汽轮发电机的定子绕组通常采用多根空、实心股线并绕的复杂编织换位结构,针对尺寸相差悬殊的复杂结构使得其定子流固耦合模型的数值求解存在网格数量多、容易出现奇异解的难点问题,该文提出三维区段式流固耦合网格划分方法,根据不同区段股线的结构及传热特点,通过非均匀网格划分方法大大降低求解模型的网格数量,实现计及复杂换位结构的定子流固耦合模型的数值求解,并通过一台124万kW水氢氢冷汽轮发电机的短路型式实验进行验证。在此基础上,提出定子绕组的新型交叉换位方法并与传统换位方法的温度进行对比,结果表明,新型交叉换位方法使定子绕组股线以及绝缘的温度分布更加均匀,并且能够有效降低定子绕组最高温度。

超超临界汽轮发电机组再热汽门阀盖螺栓断裂失效分析

某超超临界汽轮发电机组再热汽门螺栓在机组等级检修期间发现有不同程度的断裂或裂纹,对其进行了金相分析和结构检查,并对断裂原因进行了详细分析。将原有再热汽门螺栓全部更换为新材料新工艺加工的螺栓,同时对安装工艺进行了严格规范,提高了机组运行的安全性。