针对电网中微弱电流的测量需求,研制了基于隧穿磁阻效应的百μA级无接触式微电流传感器,并对微电流传感器进行低噪声设计,包括电源模块、放大模块、调零和输出模块.测试了采用不同传感芯片传感器的微弱电流探测能力,其最小可测电流幅值为280 μA,对应传感器的带宽达10kHz.并对传感器系统各模块的噪声水平进行了测量分析与计算,结果表明隧穿磁阻芯片的1/f噪声(低频噪声)是限制传感器最小可测电流幅值的主要因素.该微电流传感器可以适应智能电网微弱电流测量需求.

目前串补电容常采用电脉冲触发火花间隙作为其快速旁路保护,实现这种触发方式的难点在于确保整个触发装置与高压端的电气隔离.为解决此问题,研制了一种激光触发火花间隙,对其进行了自击穿和触发击穿测试,通过实验比较了相同形状尺寸的激光触发火花间隙与电脉冲触发火花间隙在不同极性、不同间隙距离下的触发击穿电压,并对2种火花间隙的放电机理进行了初步分析.实验结果表明:激光触发火花间隙的最小可靠触发击穿电压在自击穿电压的26％～48％之间;电脉冲触发火花间隙的最小可靠触发击穿电压在自击穿电压的43％～64％之间;两种火花间隙正极性下的最小可靠触发击穿电压均低于负极性下的最小可靠击穿电压.

The differential protection for power transformers features less ratio of proper actuation and slow response,because it severely suffers from false differential current caused by core saturation.Investigation shows that transformer core saturation needs certain time,so emergence time of abrupt differential current of inrush is lager than the time of abrupt change phase voltage.And it can be utilized to distinguish internal faults from external faults.A new criterion for transformer differential protections based on abovementioned time difference is proposed.Furthermore,a novel filter algorithm is designed in order to ensure fast and accurate detecting,effective noise-repressing as well as high-speed response during the instant of variation emergence.The EMTDC-based simulation,which covers various fault situations,is analyzed,and the test results confirm that the criterion can effectively prevent the differential protection from mal-operating and guarantee the high-speed response to the internal fault as well.

本文介绍了清华大学非电专业"计算机硬件技术基础"课程在能力导向理念下的教学目标、教学内容、教学方法、成绩评定和教学效果,着重描述了"以学生为本、培养学生综合能力"的教学思想在各教学环节中的具体实施。

详细介绍了低压电力线远程抄表系统各组成部分的原理与软、硬件实现.该系统采用过零点扩频通信方案大大提高了通信成功率,使用主动式看门狗电路提高系统的电磁兼容性.集中器在硬件结构上采用3种存储技术,提高了用户电量数据的可靠性.低压电力线通信信道具有信号衰减大、噪声高、信号传输具有时变性和频变性的特点,运用自动中继技术可使抄到率达到100%.集中器与管理中心采取GPRS通信方式,具有连接方便可靠的优点.系统实际运行情况良好.

This paper presents the last applied result of low-voltage power line communication technology. For the first time overall power network elements are described and their effect on the performance of the remote meter reading system is considered. According to the qualitative analysis by the transmission matrices model,transfer function,as a result of standing wave,presents maximum or minimum at some frequency in the range of 50kHz-500kHz. Multi-carrier technology possesses characteristic of anti frequency-selective fading. Reliability is improved when information is transmitted at zero-crossing of voltage on account of slight noise.

In the light of the demands of loss reduction on the transmission lines and the improvement of the voltage quality of the10kV distribution network,taking into ac-count the shortage of traditional reactive power compensation methods,an attempt is introduced on distributed reactive power compensation based on total optimum.The solution of optimum method and terminal device is given too.

There are many means in reducing the active power loss of a distribution network, two important methods are feeder reconfiguration and capacitor placement. The minimum nodal voltage method (MNV) and genetic algorithms (GA) are chosen to solve the network reconfiguration problem and capacitor placement problem, respectively. These two means are combined together so that a much better effect of loss reduction can be achieved than either method alone. The methods presented in this paper have been testified in real-time applications in an actual distribution network.

In the light of the demand for communication methods for the remote data collection system of distribution networks and the shortage existing in the current communication method, an attempt of applying GSM SMS service in the remote data collection system of distribution network is introduced. With a comparison among the economization, reliability and the communication capability, the feasibility and the relative advantage of the data collection system based on the SMS service is synthetically demonstrated. A specific system resolution is introduced.

During the process to actualize the distribution management system of Liaoyang Power Supply Company, how to combine the power enterprise's manufacture with its management and effectively exert the full advantages and effects of geographical information system (GIS), is successfully resolved. This system adopts ArcSDE GIS platform, not only avoids the difficulty of exploiting foreign software system repeatedly, but also solves the data share question of power manufacture, management and other data information on a common platform. The system control and market decision-making system are also integrated In this distribution management system.

A scientific design method was introduced to decrease the grounding resistances of two 110 kV urban substations' grounding systems in this paper. The first step of the grounding system design process is to gain the soil structure, and the second step is to design the grounding system by numerical analysis according to the multi-layer soil structure model. The peripheral geographical conditions have been taken into consideration to effectively decrease the grounding resistances of substation's grounding system.

More and more high voltage transmission lines make use of rubber housed ZnO arresters in series with another air gap (for example, the insulator gap) as lighting protection elements. Many test results of ZnO arresters protection performance show that this insulation arrangement is suitable for practical lines according to results based on only simple impulse voltage. This paper uses a composite voltage (switching impulse voltage/alternating voltage) to determine the air breakdown behavior of the conductor-rod gap in series with the sphere gap. In the test, the switching impulse voltage is applied to the conductor while the alternating voltage is applied to the rod and one sphere and the other sphere is grounded. The results show that in some cases, the value of the U50% sparkover voltage for the conductor-rod gap with the composite voltage is nearly only half of that for just the simple impulse voltage.

非同步采样误差是周期性信号均值型参数数字化测量中普遍存在的一种误差。本文介绍了非同步采样误差的概念，推导了常用电工参数数字化测量中的非同步采样误差的公式，并分析了影响非同步采样误差的因素。最后提出了几种减小非同步采样误差的方法。

根据２０ＭＶＡ／１１０ｋＶＳＦ６气体绝缘变压器的结构，提出了考虑损耗后变压器绕组暂态电压分布计算的新方法Ｂｅｒｇｅｒｏｎ法，推导了有损耗的互感电路的等值参数和计算公式，并给出了计算结果。

论文作者研制了一种基于单片机的智能式高压电压表。该表能同时测量与显示交流有效值和峰值（交流试验）或直流平均值和峰值（直流试验），并且该表具有峰值自动保持、交直流试验自动判别、量程自动选择等功能。使用十分方便。