异频大电流接地装置测试系统设计与实现

发布时间：2018-03-05 15:06

  本文选题：变电站地网　切入点：接地装置测试　出处：《电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：变电站的接地系统是维护电力系统安全、可靠运行以及电力设备安全、人员安全的根本保证和重要措施。系统发生故障时,极大的短路电流经接地系统泄流,使得地网的电位发生升高,若地网的接地阻抗较大,地电位的升高可能会危及设备和人身安全。据统计,我国曾发生多起因地网接地未达到要求所导致的事故或者事故扩大,这些由接地系统引起的事故损失大都在数百万元以上,间接经济损失更为严重。4随着电网的发展、电压等级的提高以及系统容量的增大,接地短路电流将相当大,大型地网覆盖面积广、对角线长,为保证系统安全、可靠运行,对接地系统的要求需要更为严格。目前,国内流行采用异频法测量一般地网的接地电阻,对于大型地网采用异频法或大电流工频法。工频大电流法能准确测量地网接地电阻,但测量过程复杂,需要倒相来消除零序对测量结果的影响,抗干扰能力差;异频法与工频大电流法相比,能消除地网的高频干扰,测量结果不受系统电源的影响,但实验电流较小,不能真实反映大型地网的运行状态。大型地网除接地电阻外,由于电抗的影响,在土壤电阻率低的地方,其感性分量很可能比阻性分量大,感性分量也不能忽略,另外,接触电位、跨步电位、场区地表电位梯度能反映地网运行的状态,在大型地网测量也不可忽略。为准确掌握大型地网状态,精确测量大型地网相关参数,本项目深入研究异频法,在一般异频法基础上,汲取工频大电流法优点,提出采用大电流异频信号对大型、不均匀地网进行测量,成功开发了大电流异频测试系统,既能可有效消除干扰对测量结果的影响,又能实现地网跨步电压、接触电势、场区地表电位梯度分布曲线等参数测量,可进行多次重复测量,消除了偶然因素影响,能真实反映大型地网的运行状态,满足现场测量的需要,具有较高的实用价值。
[Abstract]:The grounding system of substation is the fundamental guarantee and important measure to maintain the safety and reliability of power system, the safety of power equipment and the safety of personnel. If the grounding impedance of the grounding grid is large, the increase of the ground potential may endanger the equipment and personal safety. According to statistics, there have been many accidents or accidents caused by the grounding failure to meet the requirements in our country. Most of these accidents caused by grounding system are more than millions of yuan. The indirect economic loss is more serious. With the development of power network, the increase of voltage level and the increase of system capacity, the grounding short-circuit current will be quite large. In order to ensure the safety and reliability of the system, the requirements of grounding system should be more strict. At present, it is popular to use different frequency method to measure the grounding resistance of general ground grid in our country. Different frequency method or high current power frequency method is used for large scale ground network. The power frequency and large current method can accurately measure grounding resistance of ground grid, but the measuring process is complicated, so it is necessary to eliminate the influence of zero sequence on the measurement result by inverting phase, and the anti-interference ability is poor. Compared with the power frequency and high current method, the different frequency method can eliminate the high frequency interference of the ground net, and the measurement results are not affected by the power supply of the system, but the experimental current is small and can not truly reflect the operation state of the large ground network. Because of the influence of reactance, the inductive component of soil resistivity is likely to be larger than that of resistive component, and the inductive component can not be ignored. In addition, the contact potential, stride potential, and the gradient of surface potential in the field area can reflect the operation state of the earth network. In order to accurately grasp the state of large-scale ground network and accurately measure the related parameters of large-scale ground network, this project deeply studies the method of different frequency, and based on the general method of different frequency, draws the advantage of power frequency and large current method. It is proposed that the large and uneven ground net be measured by using the high current different frequency signal, and the large current different frequency measurement system is developed successfully. The system can not only effectively eliminate the influence of interference on the measurement results, but also realize the step voltage and contact potential of the ground network. The field area surface potential gradient distribution curve and other parameters measurement can be repeated many times, eliminating the influence of accidental factors, can truly reflect the operation of large-scale ground network, meet the needs of the field survey, has a higher practical value.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM862
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本文编号：1570745