氧化锌避雷器运行状态分析研究
发布时间：2018-11-20 08:28
【摘要】：当今科学技术发展突飞猛进,电力是各行各业前进的基础,电力系统的安全供电、经济送电是安全生产和减少经济损失的重要保证,因而必须对电力设备进行有效的保护。氧化锌避雷器(简称MOA)被广泛应运于电力系统中,它与被保护设备并联,当雷击过电压发生时,依靠自身的非线性特性达到对电力设备的保护。运行状态的分析判定是确保避雷器正常工作的前提,对电力设备甚至整个电力系统的安全可靠运行具有重要的意义。世界各国对MOA运行状态分析的方法很多,如总泄流电流法、基次谐波法、三次谐波法、补偿法、双“AT”检测法等。这些方法,虽然能在一定程度上能反映MOA的运行状况,但是检测精度不高,甚至造成对MOA运行状态的误判,因此必须对MOA运行状态的分析方法进行改进,提高其准确度。本文在总泄流电流的基础上利用新阀值平移不变量的小波去噪法,来抑制传统阀值去噪法所产生的伪吉布斯现象,从而获得比较准确的避雷器全泄露电流信号,并用仿真软件来验证方法的有效性,它能精确判断出MOA晚期老化运行状况,早期和中期老化判断困难。为了更好的判断MOA早期和中期老化运行状态,本文研究了基于电容法的改进算法,针对谐波干扰幅值及相位的不确定性,直接测量总阻性电流可能会导致MOA运行状态的误判,而电容法中没有排除谐波电压对三次谐波阻性泄漏电流的影响,因而对电容法进行改进,通过两种方法的仿真对比,分析了不同谐波比重以及不同谐波相位带来的影响,各次谐波阻性电流幅值都随着谐波电压相位的增大而增大,谐波电压幅值增大而波动增加,两种算法在基波电阻泄漏电流基本一致,然而用电容法来分析三次阻性谐波电流,误差较大,而新算法中,利用电流之间的近似相位关系,补偿了谐波电压作用下的阻性泄漏电流分量,从而得到基波电压下的基波阻性电流和三次谐波阻性电流的精确值,从而对MOA早期和中期有更准确的判断。但是当避雷器处于晚期老化时,新算法误差有时比电容法还大,且测得的三次谐波阻性电流值变化趋势混乱,新算法在此无效,必须综合前章的方法来进行避雷器晚期老化的判断。综合两种分析方法,我们可以对MOA早期、中期和晚期老化进行科学的评估,对电力系统安全运行有重要意义。
[Abstract]:Nowadays, with the rapid development of science and technology, electric power is the basis of the progress of various industries. The safe power supply of power system and economic power transmission are the important guarantee of safe production and reducing economic losses. Therefore, it is necessary to protect the power equipment effectively. Zinc oxide arrester (MOA) is widely used in power system. It is parallel to the protected equipment. When lightning overvoltage occurs, the protection of power equipment can be achieved by its own nonlinear characteristics. The analysis and determination of operation state is the premise to ensure the normal operation of the arrester, which is of great significance to the safe and reliable operation of the power equipment and even the whole power system. There are many methods to analyze the running state of MOA in the world, such as the total discharge current method, the basic harmonic method, the third harmonic method, the compensation method, the double "AT" detection method and so on. Although these methods can reflect the running status of MOA to a certain extent, the detection accuracy is not high, and even results in misjudgment of the running state of MOA. Therefore, it is necessary to improve the analysis method of running state of MOA to improve its accuracy. In this paper, based on the total discharge current, a new wavelet de-noising method is used to reduce the pseudo-Gibbs phenomenon produced by the traditional threshold de-noising method, so as to obtain the accurate full leakage current signal of the arrester. The simulation software is used to verify the validity of the method. It can accurately judge the running state of late aging of MOA, and it is difficult to judge early and middle aging. In order to judge the early and intermediate aging state of MOA, an improved algorithm based on capacitance method is studied in this paper. In view of the uncertainty of amplitude and phase of harmonic interference, direct measurement of total resistive current may lead to misjudgment of running state of MOA. But the capacitance method does not exclude the influence of harmonic voltage on the third harmonic resistance leakage current, so the capacitance method is improved. Through the simulation and comparison of the two methods, the influence of different harmonic specific gravity and different harmonic phase is analyzed. The amplitude of harmonic resistive current increases with the increase of harmonic voltage phase, and the amplitude of harmonic voltage increases with the increase of harmonic voltage amplitude. The two algorithms are basically consistent in the leakage current of the fundamental resistance. However, the capacitance method is used to analyze the third-order resistive harmonic current. In the new algorithm, the resistance leakage current component under harmonic voltage is compensated by using the approximate phase relation between currents, and the accurate values of the fundamental resistance current and the third harmonic resistance current are obtained. Therefore, the early and middle MOA have a more accurate judgment. However, when the arrester is in the late stage of aging, the error of the new algorithm is sometimes greater than that of the capacitance method, and the measured third harmonic resistive current values tend to change in confusion. The methods in the previous chapter must be integrated to judge the late aging of arresters. By synthesizing two analytical methods, we can scientifically evaluate the early, middle and late aging of MOA, which is of great significance to the safe operation of power system.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM862
本文编号：2344396
[Abstract]:Nowadays, with the rapid development of science and technology, electric power is the basis of the progress of various industries. The safe power supply of power system and economic power transmission are the important guarantee of safe production and reducing economic losses. Therefore, it is necessary to protect the power equipment effectively. Zinc oxide arrester (MOA) is widely used in power system. It is parallel to the protected equipment. When lightning overvoltage occurs, the protection of power equipment can be achieved by its own nonlinear characteristics. The analysis and determination of operation state is the premise to ensure the normal operation of the arrester, which is of great significance to the safe and reliable operation of the power equipment and even the whole power system. There are many methods to analyze the running state of MOA in the world, such as the total discharge current method, the basic harmonic method, the third harmonic method, the compensation method, the double "AT" detection method and so on. Although these methods can reflect the running status of MOA to a certain extent, the detection accuracy is not high, and even results in misjudgment of the running state of MOA. Therefore, it is necessary to improve the analysis method of running state of MOA to improve its accuracy. In this paper, based on the total discharge current, a new wavelet de-noising method is used to reduce the pseudo-Gibbs phenomenon produced by the traditional threshold de-noising method, so as to obtain the accurate full leakage current signal of the arrester. The simulation software is used to verify the validity of the method. It can accurately judge the running state of late aging of MOA, and it is difficult to judge early and middle aging. In order to judge the early and intermediate aging state of MOA, an improved algorithm based on capacitance method is studied in this paper. In view of the uncertainty of amplitude and phase of harmonic interference, direct measurement of total resistive current may lead to misjudgment of running state of MOA. But the capacitance method does not exclude the influence of harmonic voltage on the third harmonic resistance leakage current, so the capacitance method is improved. Through the simulation and comparison of the two methods, the influence of different harmonic specific gravity and different harmonic phase is analyzed. The amplitude of harmonic resistive current increases with the increase of harmonic voltage phase, and the amplitude of harmonic voltage increases with the increase of harmonic voltage amplitude. The two algorithms are basically consistent in the leakage current of the fundamental resistance. However, the capacitance method is used to analyze the third-order resistive harmonic current. In the new algorithm, the resistance leakage current component under harmonic voltage is compensated by using the approximate phase relation between currents, and the accurate values of the fundamental resistance current and the third harmonic resistance current are obtained. Therefore, the early and middle MOA have a more accurate judgment. However, when the arrester is in the late stage of aging, the error of the new algorithm is sometimes greater than that of the capacitance method, and the measured third harmonic resistive current values tend to change in confusion. The methods in the previous chapter must be integrated to judge the late aging of arresters. By synthesizing two analytical methods, we can scientifically evaluate the early, middle and late aging of MOA, which is of great significance to the safe operation of power system.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM862
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