外加电源式100％定子接地保护的研究

发电机定子接地故障会导致运行中的发电机组严重损坏,传统双频式100%定子接地保护在现代化的发电机保护中已经不能满足要求,外加电源式100%定子接地保护具有不受发电机运行工况和状态的影响、无保护死区、高灵敏的特点将逐步取代传统双频式100%定子接地保护。在Matlab中建立模型,通过仿真分析检验其科学性和合理性。结果证明,外加电源式100%定子接地保护有很高的灵敏度,且没有保护死区,是非常理想的发电机定子接地保护。     

水电站微机发电机转子接地保护装置的原理与设计

叙述了水电站综合自动化系统中微机发电机转子接地保护装置的基本原理、软硬件设计。本装置以高速高性能微处理机及实时多任务操作系统为基本开发手段，利用切换采样原理构成机组励磁回路一点和两点接地保护，测定转子接地故障点位置和过渡电阻的大小。     

基于DSP的发电机转子接地保护装置设计

针对发电机实际运行中常出现励磁回路接地故障,提出了一种基于微机(DSP)的发电机转子接地保护装置的设计方案.在研究发电机转子接地保护原理的基础上,给出并分析了硬件系统方案设计及转子接地检测系统软件设计,试验测试结果表明,该装置灵敏性、可靠性较高,现场运行效果良好.     

TQFR-3000型主发电机定子接地修复

主发电机是内燃机车的重要大部件之一,它的工作性能直接影响机车的运行情况.如果主发电机定子发生接地,就会造成机破或临修.主发电机定子接地对小辅修段都要送出去大修,大修费用也很高.2000年8月我段成功修复7513号机车主发电机定子接地,现已走行12万.下面我介绍一种方法,仅供没有电机大修能力的段参考.     

某项目发电机中性点接地方式及接地装置选型

通过对非洲某国电站发电机的中性点接地方式进行分析,对发电机中性点接地变压器的选型进行了工程计算,指出发电机中性点接地变压器的参数选择须与发电机定子接地保护相配合。在发电机定子绕组绝缘有较高安全系数的情况下,接地电阻的选取应主要满足限制接地故障电流及与定子接地保护配合的需要。     

390H全氢冷发电机定子接地故障的分析及处理

介绍了390H全氢冷发电机结构特点,分析了定子线圈端部接地故障的原因,采取了合理的修复措施,提出日常维护中需加强定子槽楔和铁芯紧密度的检查.     

谐振补偿在大型发电机中性点接地中的应用

详细分析了发电机中性点经消弧线圈谐振补偿接地方式的应用原理,提出一种发电机中性点接地方式,并且与中性点经接地变压器高电阻接地方式进行比较。这种中性点接地方式可以更好地限制定子单相接地时的故障电流,从而保护了定子铁心和绕组。采用多回路分析方法对三峡左岸一种700 MW的大型发电机进行仿真计算,仿真结果表明此方法是可行的。     

变电所微机装置防雷保护

介绍了区域变电所微机保护装置改造后的常发性故障——微机保护装置落雷损坏的现象及其成因,提出了微机保护装置防雷保护的处理步骤,对微机保护装置的安全运行具有重要意义。     

发电机中性点局部放电在线监测系统研究

针对大型发电机定子绝缘的局部放电在线监测是预防发电机突发性事故的最有效手段,设计了一套发电机中性点局部放电在线监测系统,运用宽频带测量技术在发电机中性点获取局放信号,采用分层式网络结构框架提供局放的集成监测及远程诊断平台,验证了在发电机异常状况下局放传感器的高可靠性,分析了传感器的安装对发电机单相接地故障下的零序电压保护、故障接地电流、暂态过电压及高压系统传递过电压的影响.     

接地变压器二次电阻偏小的注入式定子接地保护解决方案

注入式定子接地保护可为机组在各种工况下的安全运行提供有力保障。分析了二滩水电站注入式定子接地保护的基本配置、测量原理和基本逻辑,结合发电机中性点接地方式及设备参数分析了接地变压器二次电阻对保护测量精度的影响,针对接地变压器二次电阻偏小的实际情况,从减少对发电机运行工况的影响和节约投资的角度出发,采用了加装隔离变压器提高保护测量精度的方案,理论分析和现场试验数据验证了解决方案的可行性和有效性。该方案为同类型机组的保护配置提供了有力参考。     

Analysis of operating conditions of ground-fault protection schemes for generator stator winding

This paper presents results of simulation studies of the influence of methods of grounding the stator winding of the unit-connected generator neutral on the operating conditions of a 100-percent ground-fault protection excited by the third-harmonic voltage ratio in the generator neutral and at its terminals. The analysis was performed for a generator with the neutral grounded through a ground-fault neutralizer, a third-harmonic stop filter, a resistor, and a capacitive voltage divider. The influence of the parameters of the particular elements of the grounding circuits on the voltage-feeding measuring element of the protection was determined. The capacitance to ground of the generator breakers was taken into account. The simulations were run for 1110-MVA unit-connected generator at ground faults along the whole length of the generator stator winding. It has been found that the method of grounding the generator neutral and the parameter of the grounding elements significantly influences the operating conditions of this protection. It is shown that through the proper selection of these parameters, the ground-fault protection of whole stator winding, counting from the generator neutral to the terminals is ensured.     

注入信号频率对注入式定子接地保护的影响

为研究注入信号频率对发电机注入式接地保护测量灵敏度、测量误差方面和保护注入功率的影响,得到注入式定子接地保护外加注入源频率的最佳选择范围,提升注入式定子接地保护的测量精度.通过MATLAB/SIMULINK模块仿真计算分析说明了采用电流判据的局限性,并得出注入信号的最佳选择范围.结果表明:注入信号的最佳选择范围低频区间为10～30Hz,高频区间为70～80Hz.     

A nondifferential protection scheme for generator stator windings

This letter presents a new technique for generator protection. The fault-generated transient current signals are detected using a multichannel transient detection unit, then the spectral energies at different frequency bands are extracted and compared to discriminate between internal and external faults. Simulation results show that the scheme demonstrates good sensitivity to low-level and interturn faults     

燃气轮发电机变频启动特点和保护配置分析

结合西门子燃机和三菱燃机的典型配置,介绍了燃气轮发电机静态变频启动(SFC)装置的结构、工作原理和保护配置。基于燃气轮发电机SFC的步骤,分析了SFC的特点以及对发电机保护的影响。通过理解和分析低频过流保护、SFC装置直流接地保护的设计思想,提出了减少燃气轮发电机SFC过程中,防止发电机差动保护、频率保护和逆功率保护误动的措施,实际运行表明这些技术措施是可行的。     

Influence of generator load conditions on third-harmonic voltages in generator stator winding

The influence of changes in load conditions of the generator-transformer unit on the operating conditions of the 100% ground-fault protection of the generator stator winding based on the third-harmonic voltages was analyzed. The analyzed stator ground-fault protection system is by ratio of the voltages third harmonic in generator neutral and at the generator terminals. The third-harmonic voltages were determined on the base of the experimental tests (measurements) run in real conditions at changes in active and reactive load conditions of the generator. It was found that mainly the generator active load influences the voltage feeding the measuring element of ground-fault protection. Therefore, determining operating conditions of ground-fault protection the influence of the generator active and reactive load should be deeply considered. This can ensure the proper operation of the ground-fault protection based on the voltage third harmonics in the whole range of the changes in generator load. Considering the influence of changes in generator load on the third-harmonic voltages (feeding measuring element of the protection system) will allow eliminating irregular generator tripping as a result of unselective operation of these protections.     

一起机端断路器非全相合闸案例的分析与思考

本文介绍了一起带机端断路器(GCB)机组非全相合闸并网的实例,分析了并网前后的零序电压接地保护动作情况,对故障时GCB两侧电压特征量进行了理论分析,并结合实际录波数据进行了验证.通过分析与研究,提出了增设机端断路器非全相保护的必要性与可行性,给同类型接线方式的发变组运行维护提供参考,提升发电机安全运行水平.     

Ground-fault currents in unit-connected generators with differentelements grounding neutral

The results of the analysis of zero-sequence currents flowing in generator neutral and at ground-fault location during the generator normal operation and during ground-faults in the stator windings are presented. The influence of different methods of grounding the generator neutral on these currents in the primary circuits for different parameters of generators, transformers and additional capacitance to ground of the generator breakers was determined. This influence was analyzed for generators with ungrounded neutral, for generators with the resistance in neutral and for generators with ground-fault neutralizer (GFN) grounding the generator neutral. The analysis has been done for real resistance of the breakdown channel during ground-faults along the whole length of generator stator winding. It has been found that the applied method of grounding the generator neutral, the parameters of generator and transformer, the additional capacitance to ground of the generator breakers, level of fault resistance and ground-fault location have a substantial influence on currents flowing in the generator neutral and at ground-fault location in the breakdown channel in the main insulation of a generator stator winding     

Design space exploration of gyrocopter‐type airborne wind turbines

This paper presents a multidisciplinary framework for the design and analysis of gyrocopter‐type airborne wind turbines. In this concept, four rotary wings provide lift to a flying vehicle, and excess power is extracted using gearboxes and generators before being transferred to the ground through electrical conductors embedded in a structural tether. A physical breakdown of the system was performed, and five models were constructed: wind model, rotor aerodynamics, structural mass, electrical system, and tether (structures and aerodynamics). A stochastic optimizer in the framework enforces interdisciplinary compatibility and maximizes electrical power transmitted to the ground under various operating conditions. The framework is then used to explore the design space of this advanced concept in numerous flight conditions. The effect of implementing new technologies was also studied in order to evaluate their effect on the overall performance of the system. It is shown through a 1.3MW design that a gyrocopter‐type airborne generator could provide more power than a ground‐based wind turbine for a given blade radius, although only a fraction of the available wind power can be harvested using off‐the‐shelf technologies and components. The work presented in this study demonstrates the challenges of designing a high altitude wind generator and shows that performance is affected by complex interactions between each subsystem. Copyright © 2015 John Wiley & Sons, Ltd.     

新型分布式热电冷三联供系统应用

本系统采用天然气发电机组、溴化锂机组和地源热泵机组等组成高效的热电冷三联供系统。夏季,溴化锂机组和地源热泵机组产生的冷水汇总送至用冷区域用于制冷;冬季,发电机组冷却高低温循环水通过板式换热器产生与地源热泵机组和溴化锂机组品质相同的热水,汇总送至用热区域用于采暖。本文阐述了利用燃气内燃机发电的余热,带动溴化锂机组,结合地源热泵技术,提高了能源的梯级利用,满足了用户的能量需求,同时大幅度减少能源费用支出。     

新型分布式热电冷三联供系统应用

本系统采用天然气发电机组、溴化锂机组和地源热泵机组等组成高效的热电冷三联供系统。夏季,溴化锂机组和地源热泵机组产生的冷水汇总送至用冷区域用于制冷;冬季,发电机组冷却高低温循环水通过板式换热器产生与地源热泵机组和溴化锂机组品质相同的热水,汇总送至用热区域用于采暖。本文阐述了利用燃气内燃机发电的余热,带动溴化锂机组,结合地源热泵技术,提高了能源的梯级利用,满足了用户的能量需求,同时大幅度减少能源费用支出。