特高压直流输电系统无功控制策略研究

介绍特高压直流输电系统中无功控制的滤波器的配置策略、滤波器投切顺序控制、滤波器限电流控制、无功控制和电压控制、滤波器无功控制及无功定置自适应控制、谐波性能控制、分离母线无功控制、CSD控制、无功和电压测量异常处理,零功率试验时无功控制处理,GammaKick控制,并进行必要的分析,提出了有利于现场运行的有效建议。     

提高重复控制逆变电源的负载瞬态响应特性

基于重复控制和PID控制方法,提出了一种重复控制和PID控制相结合的控制方法,当控制方法在稳态时采用重复控制,在非周期扰动时采用PID控制,仿真结果表明该控制方法在具有高质量的稳态波形的同时,对非周期扰动也具有很快的响应速度。     

基于ST7MC的无刷直流电机控制模式分析

1引言 电压控制模式和电流控制模式是无刷直流电机调速的两种方法.电压控制模式控制简单,通过改变绕组端电压的PWM占空比就能调节电机速度;电流控制模式能够通过电机绕组电流的调节,进行直接转矩控制,实时响应负载变化.本论文针对ST7MC控制下的无刷直流电机电压控制模式和电流控制模式进行分析,并通过比较和实际电路应用说明了电流控制模式在电动自行车控制中的优势.     

基于内模--PID控制的球磨机负荷控制系统的设计

基于中储式制粉系统的工作特性和控制难度，提出了把振动信号和差压信号相结合表征磨煤机的存煤量，并采用比例、积分、微分控制(PID)与内模控制相结合的控制球磨机负荷的串级控制模型。良好的仿真效果表明，这种方法能有效地提高系统的自适应能力，改善了系统的控制效果。内模控制与PID控制相结合的控制方式能广泛用于工业过程控制。     

基于重复控制和滑模控制的APF电流控制方法

针对传统PI控制无法实现无静差跟踪控制和难以保证在负载突变或参考电压跳变时对直流侧电压进行快速精准控制,提出了一种基于重复控制和滑模变结构控制的APF电流控制方法。该方法在传统PI控制的基础上,融合了滑模变结构控制和重复控制的优点,将重复控制引入电流内环控制中,对APF输出电流进行快速跟踪控制,将滑模变结构控制引入电压外环控制中,对直流侧电压进行快速精准控制。仿真及实验结果证明了提出的电流控制方法相比于传统PI控制方法具有更高的谐波补偿精度及更快的动态响应速度。     

有源电力滤波器控制方法综述

谐波问题日益严重,有源电力滤波器(APF)是补偿电力系统谐波及无功功率的重要装置,其控制方法对其性能有很大的影响。因此,提出了许多有源电力滤波器的控制方法。简要介绍了单周控制、滞环电流控制、空间矢量调制、无差拍控制、滑模控制、重复控制、预测控制、模糊控制、自适应控制、迭代自学习控制、无源性控制、人工神经网络控制在APF中的应用,进行对比分析,指出它们各自的优缺点及一些改进的方案,并展望了未来控制方法的发展方向。     

三菱MR-J3系列伺服系统

三菱通用交流伺服放大器MR-J3系列是在MR-J2S系列的基础上开发的具有更高性能和更高功能的伺服系统,其控制模式有位置控制、速度控制和转矩控制以及它们之间的切换控制方式可供选择。该伺服放大器应用领域广泛,不但可以用于机械工具和一般工业机械等需要高精度位置控制和平稳速度控制的应用,也可用于线性控制和张力控制的领域。该产品具有     

提高输变电工程施工质量的一些措施

输变电工程质量控制包括设计阶段的质量控制和施工阶段的质量控制,文中就当前输变电工程质量控制存在的一些问题提出了质量控制的具体措施。     

双馈风力发电机控制方法的分析研究

首先详细研究了风力发电系统中双馈电机的基本原理,在此基础上分析了双馈风力发电机的矢量控制和直接转矩控制两种控制方法。着重分析了两种控制方法的控制原理、控制过程。并根据两种控制方法的控制原理和控制过程得出双馈风力发电系统的矢量控制和直接转矩控制的控制原理图。最后对所研究分析的两种方法的优缺点进行比较。提出了该领域目前存在的一些问题。为该领域的研究提供借鉴。     

基于SVPWM和电流调节控制的无位置传感器BLDCM的起动控制

针对无位置传感器的永磁无刷直流电机的起动控制,分析了二二导通三相逆变器的电压空间矢量PWM控制,提出了具有二二导通的SVPWM控制和电流调节控制的无位置传感器BLDCM的起动控制,其中电流调节控制采用两点式比较器控制。该起动控制方法不但能有效控制起动电流大小,而且改善了BLDCM开环起动性能。通过仿真比较表明,在保持对二二导通BLDCM电流调节控制的基础上,SVPWM起动控制比升频起动控制性能更好。     

Development of integrated solutions for the decentralisation of electricity supply to power-hungry regions

The relevance of the study is conditioned by the need for practical development and implementation of integrated solutions for the decentralisation of power supply to various geographical regions suffering from a shortage of electric energy due to pronounced problems with the energy supply. The purpose of this study is to identify the main aspects of the development of integrated solutions for the decentralisation of energy supply to power-hungry regions, which may be of significant practical importance from the standpoint of improving the quality of energy supply to such regions. The leading methodological approach in this study is a combination of methods of system analysis of existing principles for the development of integrated solutions for the decentralisation of electricity supply to regions suffering from power shortages, with an analytical investigation of various aspects of electricity supply to power-hungry regions, which is of significant practical importance in terms of improving the quality of electricity supply to remote settlements and districts of the Republic of Kazakhstan. The results obtained clearly indicate the existence of significant prospects for the use of alternative sources of electricity in the issues of decentralisation of power supply to power-hungry regions, and also demonstrate the sequence of development and practical implementation of integrated solutions aimed at timely solving this problem, aimed at meeting the demand for electric energy of residential facilities in these regions and industrial production located in them. The results of this study and the conclusions formulated on their basis are of significant practical importance for employees of power supply systems, who solve practical issues of electric energy supplies to remote geographical regions suffering from power shortages.     

Improvement of automatic control systems of high-power turbines of PAO tubroatom for nuclear power plants

The main technical solutions applied by PAO Turboatom used as the compensatory measures at the increase of the period of nonstop operation of nuclear power plants' (NPP) turbines with VVER-1000 type reactors up to 18 months are (1) replacing the standard hydraulic speed controller with an electronic one, (2) introduction of overclocking protection, (3) modernization of units of stop-control valves of high pressures, (4) installation of locking dampers on the receiver tubes of turbines of the first and second modification, and (5) improving the quality of repairs by reviewing the requirements for their implementation. The introduction of complex diagnostics of a control system on the basis of automatic treatment of results of registration of working parameters of the turbine is allocated as a separate prospective direction. Using an electronic controller of speed makes it possible to simplify the procedure of its inclusion in work at the failure of an electro-hydraulic system of control and vice versa. The regimes of maintaining the turbine rotor speed, steam pressure on the outlet of turbine, and the positions of main servomotors were introduced into the functions of the electronic controller. An electronic controller of speed includes its own electro-hydraulic transducer, turbine rotor speed sensor, and sensors of the position of main servomotors. Into the functions of electro- hydraulic control system and electronic speed controller, the function of overclocking protection, which determines the formation of commands for stopping the turbine at the exceeding of both the defined level of rotation speed and the defined combination of achieved rotation speed and angular acceleration of rotor, was introduced. To simplify the correction of forces acting on the control valve cups, the design of the cups was changed, and it has the profiled inserts. The solutions proposed were implemented on K-1100-60/1500-2M turbines of Rostov NPP. From the composition of control system of already made turbines, the devices of speed switching of moving of control flaps for opening and hydraulic damper in the servomotors of regulating flaps were excluded; the fists of the control valves providing the increased valve stroke for opening and the construction of filters for regulation, electro-hydraulic converters, oil draining device, etc. was changed.     

交联聚乙烯交联度对材料击穿强度的影响

为了研究XLPE材料交联度对其电气性能的影响,制备不同交联度的XLPE样本并对其进行电气击穿实验,分析在不同的交联度区间范围内样本击穿场强变化。利用温度-时间控制法制备六组不同交联度的XLPE样本;利用差式扫描量热仪测量得到样本结晶度;利用交流变压器测量得到样本的击穿强度。实验结果表明,随着交联度上升,样本击穿场强呈先上升后下降趋势。在交联度为0%～75%区间范围内,样本击穿场强增加2%。在交联度为75%～88%范围内,样本击穿场强增加21.2%。而在交联度为88%～92%范围内,样本击穿场强下降5.3%。分析认为,样本的击穿强度与样本交联度和材料均匀程度有关。当交联度较低时,样本的击穿强度主要由样本交联度决定,随着交联度上升,样本击穿强度增加。但由于此时局部材料结构较为不均匀,因此击穿强度增加幅度不大。而当交联度上升至75%时,材料形成较为密集、均匀的三维网状结构,导致样本击穿场强大幅上升。而当交联度继续增加时,此时样本结晶度下降幅度较大,局部材料结构变得不均匀,导致样本击穿强度下降。     

Using the sensors of shaft position for simulation of misalignments of shafting supports of turbounits

Examples of using the method developed for the earlier proposed concept of the monitoring system of the technical condition of a turbounit are presented. The solution methods of the inverse problem—the calculation of misalignments of supports based on the measurement results of positions of rotor pins in the borings of bearings during the operation of a turbounit—are demonstrated. The results of determination of static responses of supports at operation misalignments are presented. The examples of simulation and calculation of misalignments of supports are made for the three-bearing “high-pressure rotor–middle-pressure rotor” (HPR–MPR) system of a turbounit with 250 MW capacity and for 14-supporting shafting of a turbounit with 1000 MW capacity. The calculation results of coefficients of the stiffness matrix of shaftings and testing of methods for solving the inverse problem by modeling are presented. The high accuracy of the solution of the inverse problem at the inversion of the stiffness matrix of shafting used for determining the correcting centerings of rotors of multisupporting shafting is revealed. The stiffness matrix can be recommended to analyze the influence of displacements of one or several supports on changing the support responses of shafting of the turbounit during adjustment after assembling or repair. It is proposed to use the considered methods of evaluation of misalignments in the monitoring systems of changing the mutual position of supports and centerings of rotors by half-couplings of turbounits, especially for seismically dangerous regions and regions with increased sagging of foundations due to watering of soils.     

印度工程锅炉给水泵选型设计探讨

结合美国机械工程师协会（AmericanSocietyofMechanicalEngineers,ASME）和国内标准规范,对印度某300Mw电站工程合同中给水泵在正常额定选型工况、锅炉安全阀起跳以及甩负荷选型最大连续蒸发量（boil—ermaximumcontinuerate,BMCR）工况的选型参数行分析,得到高压给水泵扬程和流量选型计算和设计的依据,提出给水泵按BMCR工况选型,再以锅炉汽包安全阀起跳和电网频率波动2种工况作为给水泵选型的出力校验方法,可作为今后同类工程技术谈判的依据和设计基础。     

Analysis of the degree of sparkling of certain commutator plates of electric machines by the photo-stroboscopic method

Analysis of the causes of failure showed that failures of a commutator and brush assembly (CBA) of electric machines make up 10–15% of the total number of failures. Many different methods to control the degree of sparkling of the CBA plates based on the measurement of different physical values and connected with the CBA sparkling processes were developed. The article describes a method of automated analysis of the degree of sparkling of certain commutator electric machine with the use of stroboscopic photo recording of sparkling and computer processing of the photo images of the sparkling plates aiming at obtaining the degree of sparkling for each collector plate. Processing methods of such images using the original OpenCV software library including image identification, classification and obtaining of the integral image and its analysis were considered. The proposed method allows the degree of sparkling under the trailing edge of the brush for each commutator plate to be determined. Determination is carried out for a large number of switching cycles for each brush, which allows statistical error to be avoided; in addition, automation of measurements decreases the influence of human factor on the test result.     

Heat transfer enhancement in steam-turbine condensers with the use of surface-active substances

A technology of the enhancement of the power efficiency of steam-turbine plants (STPs) is proposed by the treatment of surfaces of a piped condenser system over the steam and water sides with the use of surface-active substances (SAS). The transition of filmwise condensation into dropwise makes it possible to increase the heat-transfer coefficient by 50–70% because of hydrophobization of outside surfaces of the steam side that results in vacuum extension at minimum operating costs. The resulting data are verified by laboratory investigations and full-scale tests. The accumulation rate of thermobarrier deposits over the water side decreases by a factor of 6–8, and, correspondingly, the overhaul life connected with the refinement of condenser pipes increases. The maintenance of the hydrophobic film of SAS at the outside surface of condenser pipes can be provided by the periodic injection of SAS on the inlet of a low-pressure cylinder (CLP) of the turbine both in the period of short-time stops and during the operation of STPs. At the same time, because of the additional dispersion of the liquid phase, the rate of drop-impact erosion of the blade row decreases by 30%.     

基于复杂网络的产品竞争网的特性研究

专业镇经济是珠三角经济的重要特征之一,本文对以同类和关联产品为纽带的专业镇经济,从复杂网络的角度进行了分析.在专业镇企业集群的产品竞争网构建方面,提出了一个新颖的竞争选择度模型.通过基于竞争选择度模型的专业镇产品竞争网的建模分析,可以发现珠三角专业镇的产品竞争网具有比较典型的无标度和小世界特征.经过对广东顺德地区2个国内比较著名的专业镇产品竞争网的实证分析,可以大致得出与产品竞争网理论推导相符合的结论.     

Considering the summation of the effect of harmful substances during the calculation of the environmentally safe waste water discharge

This article presents the technique of assessing the maximum allowable (standard) discharge of waste waters with several harmful substances into a water reservoir. The technique makes it possible to take into account the summation of their effect provided that the limiting harmful indices are the same. The expressions for the determination of the discharge limit of waste waters have been derived from the conditions of admissibility of the effect of several harmful substances on the waters of a reservoir. Mathematical conditions of admissibility of the effect of wastewaters on a reservoir are given for the characteristic combinations of limiting harmful indices and hazard classes of several substances. The conditions of admissibility of effects are presented in the form of logical products of the sums of relative concentrations that should not exceed the value of 1. It is shown that the calculation of the process of wastewater dilution in a flowing water reservoir is possible only on the basis of a numerical method to assess the wastewater discharge limit. An example of the numerical calculation of the standard limit of industrial enterprise wastewater discharges that contain polysulfide oil, flocculant VPK-101, and fungicide captan is given to test this method. In addition to these three harmful substances, the water reservoir also contained a fourth substance, namely, Zellek-Super herbicide, above the waste discharge point. The summation of the harmful effect was taken into account for VPK-101, captan, and Zellek-Super. The reliability of the technique was tested by the calculation of concentrations of the four substances in the control point of the flowing reservoir during the estimated maximum allowable wastewater discharge. It is shown that the value of the maximum allowable discharge limit was almost two times higher for the example under consideration, taking into account that the effect of harmful substances was unidirectional, which provides a higher level of environmental safety for them.     

Problems in creation of modern air inlet filters of power gas turbine plants in Russia and methods of their solving

The main problems in creation and operation of modern air inlet paths of gas turbine plants installed as part of combined-cycle plants in Russia are presented. It is noted that design features of air inlet filters shall be formed at the stage of the technical assignment not only considering the requirements of gas turbine plant manufacturer but also climatic conditions, local atmospheric air dustiness, and a number of other factors. The recommendations on completing of filtration system for air inlet filter of power gas turbine plants depending on the facility location are given, specific defects in design and experience in operation of imported air inlet paths are analyzed, and influence of cycle air preparation quality for gas turbine plant on value of operating expenses and cost of repair works is noted. Air treatment equipment of various manufacturers, influence of aerodynamic characteristics on operation of air inlet filters, features of filtration system operation, anti-icing system, weather canopies, and other elements of air inlet paths are considered. It is shown that nonuniformity of air flow velocity fields in clean air chamber has a negative effect on capacity and aerodynamic resistance of air inlet filter. Besides, the necessity in installation of a sufficient number of differential pressure transmitters allowing controlling state of each treatment stage not being limited to one measurement of total differential pressure in the filtration system is noted in the article. According to the results of the analysis trends and methods for modernization of available equipment for air inlet path, the importance of creation and implementation of new technologies for manufacturing of filtering elements on sites of Russia within the limits of import substitution are given, and measures on reliability improvement and energy efficiency for air inlet filter are considered.