李家峡水电站水轮发电机的进相运行

水轮发电机适时进相运行 ,能改善和抑制电网电压水平。本文对李家峡水电站 1 #水轮发电机的进相运行试验进行分析 ,旨在找出水轮发电机进相运行的限制条件 ,以便提高水轮发电机的进相能力     

测试分析同步发电机进相运行的限制条件

从发电机动角、定子电流、厂用电电压等方面,对山西古交兴能电厂1号发电机组的进相限制条件进行了测试。结果表明,在发电机进相运行,有限制在有功功率为250Mw以下,定子电流不得超过额定电流的1．05倍。目前发电机组端部结构件升温、带与不带厂用电运行以及系统稳定计算极限还不会影响发电机的进相运行。     

安康水电厂4号发电机组做进相运行试验

.安康水电厂4号发电机组于1992年12月2日做了进相运行试验.这次试验是在西北电管局总调、生产处、西北电力试验研究所和安康电厂等单位的密切配合下完成的.这次进相运行试验的项目有5个:一是发电机功角测量校验:二是作发电机静态稳定极限的实际测量和失步时的参数录波;三是作发电机在有功功率分别为100MW、160MW、190MW和相应无功功率为—140Mvar、—130Mvar、—85Mvar时测量发电机端部漏磁引起的端部铁构件的温升限制曲线;四是作发电机进相运行时只带本段6kV母线时电压降低的进相负荷限制曲线;五是测定进相运行时330kV母线电压降低的数值.     

电能质量技术监督运行管理与探索

介绍电能质量技术监督工作在火电厂及供电系统中生产运行及用电管理的重要性,提出在运行、维护、管理等方面对电能质量技术监督工作的要求和建议,阐述采用科学的管理方法,先进的技术手段,通过对发电机调压功能、无功出力、进相运行及电压质量进行管理与监督,加强发电机有功功率和无功功率的调整、控制及改进,使电能质量各类指标控制在标准规定允许范围之内,确保火电厂及其供电系统用电设备的安全、经济、优质运行。     

发电机氢气纯度湿度不合格及发电机进油分析及防范

发电机进油以及氢气纯度、湿度不合格给大型发电机的安全稳定可靠运行带来潜在的危害.针对大型汽轮发电机运行中存在的氢气纯度和氢气湿度不合格、发电机内进油的原因、危害,重点阐述了如何防范发电机进油、提高氢气纯度、降低氢气湿度的措施.     

电力系统模拟试验系统的物理现象分析

鉴于电力技术的高速发展对物理模拟试验系统提出了更多新的要求,提出了新型电力系统模拟试验系统,分析了系统的各部分主要功能,并基于对模型系统与原型系统一致性的理论分析,以典型的单机—无穷大系统为例,分析了该系统在试验过程中出现的物理现象和参数变化过程。结果表明,线路发生两相故障时,故障超前相和落后相电流的大小关系取决于故障前发电机向系统输送的负荷大小;保持发电机电势不变,增加有功功率输出,当线路阻抗大于发电机同步电抗时发电机处于迟相运行,反之则处于进相运行。     

米东热电厂发电机进相运行试验分析

阐述了神华米东热电厂在进行发电机进相试验时,由于厂用电电压限制,造成试验屡次不成功,后经过分析,最终完成了发电机进相试验。     

简谈600MW发电机进油原因分析及预防措施

根据某发电公司国产600 MW汽轮发电机双流环式密封油瓦结构及机组运行情况,分析机组在启、停机阶段和运行期间,因密封油差压阀和平衡阀工作异常、消泡箱油位液位高等原因造成密封油进入发电机内,危害到机组的安全运行。从运行角度对可能导致发电机进油的原因提出发电机排补氢时要缓慢、维持油氢差压稳定等相应的预防措施,从而杜绝发电机进油。     

同步发电机进相运行试验仿真研究

鉴于进相试验是确定机组进相运行能力的依据,分析了进相试验限制条件,并对吴江热电厂需进相试验的机组进行功角估算,由此确定各工况进相运行限额。在PSCAD软件平台上建立该机组的进相试验仿真模型,仿真分析了不同工况下试验过程中各电气量的变化和影响进相深度的限制因素。与实测数据比较分析表明,仿真与实测数据的误差较小,进相运行对高压母线的降压效果以及影响进相深度的限制因素基本一致。因此,在确定新机组实际进相能力前,可通过PSCAD进行进相试验仿真为现场进相试验提供可靠依据。     

风力发电讲座第四讲 风力发电机组的并网运行

风能是我国目前开发利用比较成熟的一种新能源,风电事业正在我国蓬勃发展。为了帮助读者了解风力发电知识,我们请长期从事风力发电研究工作的中国科学院电工研究所倪受元研究员撰写了《风力发电》讲座,以飨读者。 ——编者 风能是一种不稳定的能源,如果没有储能装置或与其他发电装置互补运行,风力发电装置本身难以提供稳定的电能输出。为了解决风力发电稳定供电的问题,目前国内外比较一致的看法是：大型风力发电机 (1000千瓦以上 )并网运行;中型风力发电机 (从几十千瓦到几百千瓦 )或者并网运行,或者与柴油发电机或其他发电装置并联互补运行;小型风力发电机 (10千瓦以下 )主要采用直流发电系统并配合蓄电池储能装置独立运行。 1 恒速恒频风力发电机的并网运行 中大型或大型风力发电机 (几百千瓦到几兆瓦 )主要是采用并网运行方式,在这种运行方式中主要解决的问题是并网控制和功率调节问题。下面根据风电系统所采用的发电机类型分别作一介绍。 1 1 同步发电机的并网运行 风力驱动的同步发电机与电网并联运行的电路如图 1所示。除风力机、增速器外,电气系统包括同步发电机、励磁调节器、断路器等,发电机通过断路器与电网相联。其运行特点是： 1 同步并网同步发电机与电网并联合闸前,为了避免电流冲击和转轴受到突然的扭矩,需要满足一定的并联条件,这些条件是：风力发电机的端电压大小等于电网的电压;风力发电机的频率等于电网的频率; 并联合闸的瞬间,风力发电机与电网的回路电势为零; 风力发电机的相序与电网的相序相同。由于风力发电机有固定的旋转方向,只要使发电机的输出端与电网各相互相对应,即可保证第 4个条件得到满足。所以在并网过程中主要应检查和满足前三个条件。     

基于PMU的发电机参数量测对电网输送能力提高的研究

针对目前难以获得同步发电机实际运行工况参数的问题,利用同步相量测量单元（PMU）能直接测量发电机的功角以及机端电压和电流相角的特点．计算获得发电机实际运行的同步参数xd。将该直接测量的发电机运行参数运用于电力系统仿真计算,可提高电力系统暂态功角稳定水平和输电能力,同时也提高了系统的静态功角稳定水平。通过算例表明了此方法的实用性和方便性。     

Development and performance testing of a 200 kVA damperlesssuperconducting generator

A 200 kVA, 3000 RPM superconducting generator has been developed and tested. The rotor has been wound with superconducting wire of Nb-Ti alloy. A closed-circuit liquid helium system has been designed and installed for cooling the superconducting windings. The stator carries the air-gap type armature windings and a laminated-iron flux-shield. A new concept in the design of superconducting generators with high short-circuit ratio (more than 5) has been introduced. This eliminates the requirement of an electromagnetic damper and quick response excitation system. The generator has been comprehensively tested in the superconducting state. Open-circuit and sustained short-circuit tests, three-phase sudden short-circuit tests, synchronization with the grid and parallel operation with power systems have been conducted. The synchronous machine was operated up to its rated kVA in the four quadrants-as a generator and as a condenser with leading and lagging power factors. A few special tests on superconducting generators, which were not reported earlier, such as direct-online starting of a 20 hp squirrel-cage induction motor and negative phase sequence tests have also been performed successfully. Test results and conclusions are given     

A novel excitation scheme for a stand-alone three-phase induction generator supplying single-phase loads

This paper presents the operating principle and steady-state analysis of a novel excitation scheme for a stand-alone three-phase induction generator that supplies single-phase loads. The phase windings and excitation capacitances are arranged in the form of the Smith connection and the excitation scheme is referred to as the SMSEIG. In addition to providing the reactive power for self-excitation, the capacitances also act as phase balancers. With this novel excitation scheme, isolated single-phase loads can be supplied with good phase balance in the induction machine, resulting in high efficiency, large power output, and quiet machine operation. Performance analysis is based on the method of symmetrical components, from which the input impedance of the generator can be determined. Numerical solution of a simplified equivalent circuit for the machine variables, namely the excitation frequency and magnetizing reactance, enables the generator performance to be evaluated for any load and speed. With the aid of a phasor diagram, the conditions for achieving perfect phase balance are deduced and a method to compute the capacitances required is developed. Experimental investigations on a 2.2-kW induction machine confirm the feasibility of the SMSEIG.     

用于槽式太阳能光热发电过热一体式蒸汽发生器的概念设计

文章提出了一种兼具过热段可用于槽式太阳能光热发电系统蒸汽发生器的概念机型．介绍了它的功能及运行原理。针对光热发电系统的特点对其主体结构进行了设计,使之能够适应大温差、变负荷的运行工况。从经济性和安全性的角度出发,对其运行方案及控制方案进行了分析。     

浅析汤峪水电站发电机纵差保护误动作存在问题与处理

纵差保护作为防御发电机定子绕组及其引出线相间短路的主保护,对发电机安全高效运行起着重要作用。本文仅对该水电站机电设备运行过程中出现的纵差保护误动作四种可能性加以分析和处理,保证了发电机的安全运行。     

A generic FPGA-based PWM generator with automatic device fault recovery for fuel cell,interleaved, multi-phase and multi-switch DC/DC boost converters

This paper describes the simulation and implementation of a generic FPGA-based PWM generator with automatic device fault recovery. This PWM generator is applied to multi-switch DC/DC boost converters for fuel cell applications; these converters have gained attention due to its reliability, equally-distributed power losses and reduced part count. In this paper, three different driving schemes for one phase and different legs are described and one driving scheme has been finally chosen. The operation of the proposed PWM generator with simulations and experimental results are shown. This PWM generator with automatic fault recovery, brings more reliability and fault robustness to fuel cell boost converters, making suitable to use in electric vehicle and uninterruptible power supplies (UPS). The method used in the PWM generator described on this paper, allows to change the number of devices working in DC/DC conversion, increasing the switching frequency and the duty cycle of the power switches, ensuring a DC/DC conversion without interruption.     

Single-phase operation of a three-phase induction generator withthe Smith connection

Single-phase operation of a three-phase induction generator with the Smith connection (SMIG) is analyzed using the method of symmetrical components. It is shown that, despite the asymmetrical nature of the winding connection, balanced currents can be made to flow in the three-phase stator winding. The conditions for achieving perfect phase balance are carefully deduced. With the aid of a phasor diagram, expressions for the line power factor and line current under perfect phase balance are also obtained. The effect of the phase-balancing capacitances on the generator performance is investigated. A simple dual-mode control scheme is also proposed with a view of minimizing the phase imbalance over the practical operating speed range. Experiments conducted on a 2.2 kW induction machine confirm the validity of the theoretical analysis and feasibility of the control method     

Single-phase operation of a three-phase induction generator using a novel line current injection method

By using two capacitances and a current injection transformer, a three-phase induction generator can operate with good phase balance and line power factor while delivering power to a single-phase power grid. This paper presents a systematic analysis on this novel induction generator configuration. The solution of the system's inspection equations using the method of symmetrical components enables the steady-state generator performance at any speed to be computed. The conditions for achieving perfect phase balance are deduced from the phasor diagram. It is shown that the capacitances that result in perfect phase balance depend on the generator admittance, power factor angle, as well as the turns-ratio of the current injection transformer. Where possible, the computed results are verified by experiments conducted on a 2-kW induction machine. An experimental investigation on the system waveforms and harmonics is also carried out.     

Modeling and design of phase shift anti-islanding method using non-detection zone

Islanding phenomenon of a grid-connected independent generator like a photovoltaic (PV) system occurs when a section of a utility system is disconnected from the main utility voltage source, but the independent generator continues to energize the utility lines in the isolated section. Since islanding causes a safety hazard to utility service personnel and damage to power supply facilities as a result of unsynchronized reclosure, PV inverter is required to have anti-islanding function. In order to prevent this phenomenon, various anti-islanding methods have been studied. Even though phase shift anti-islanding method including slip mode frequency shift (SMS) method and reactive power variation (RPV) method has been regarded as a highly effective anti-islanding method, the analytical design method of that has not been cleared. This paper proposes a design guideline of the phase shift anti-islanding method based on non-detection zone (NDZ). As leading phase shift anti-islanding methods, both SMS and RPV methods are discussed to verify the validity of the proposed method. Both methods are derived analytically through the modeling and verified visually by simulation and experiment under IEEE Std. 929-2000 test condition. It is shown that both methods designed by the proposed method have effectiveness to detect islanding within 2 s and good power quality above 0.99 power factor. The presented methodology in this paper can be extended to design other active anti-islanding methods.     

A fast following synchronizer of generators

The theory and implementation of a synchronizer of generators, the fast-following synchronizer, are presented. The synchronizer is implemented by closed-loop control systems in which the motive power and the excitation current of a generator are controlled quickly and accurately so as to make the amplitude, frequency, and phase angle of the generator voltage follow those of the bus voltage of the power system in which the generator is going to be switched. The voltage across the generator breaker can be kept at zero continuously, and the generator can be switched in at any time without any surge current