基于电容隔直的单匝交直流合成大电流发生器的研制

发布时间：2018-03-04 13:38

本文选题：电流互感器　切入点：直流偏磁　出处：《华中科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：交、直流混合运行的电网结构使交、直流系统之间的相互影响愈来愈明显。直流输电网络以单极-大地回线方式运行时，交流电网中的电流互感器（CT）将会产生直流偏磁。直流偏磁会加剧CT的铁心过饱和磁化，从而影响CT的计量和保护性能。因此，研究能模拟CT直流偏磁环境的交、直流混合电流发生系统显得非常重要。目前，模拟电流互感器直流偏磁环境的交、直流混合电流发生系统主要有两种实现方法。一种是利用直流电流回路和交流电流回路同时并各自穿过电流互感器，但该方法仅限应用于穿心式电流互感器，由于现场实际运行的电流互感器一般一次导电杆已经安装好，因此这一种方法不适用于对非穿心式电流互感器进行研究。另一种方法是采用任意电流发生装置来产生含有直流电流分量的工频交流电流，虽然该方法产生的信号可以与电流互感器一次导电杆直接连接，然而它所产生的电流大小有限，而且装置体积较大、制造成本较高。本文研究了一种基于电容隔直的单匝交、直流合成大电流发生器，通过采用电容隔直技术，利用大容量无极性电容通交流、阻直流的电流特性，使直流源回路和交流源回路的共同支路中流过交流和直流的叠加电流，而交流电流源与直流电流源相互独立、互不影响，从而产生交、直流合成电流；同时，为了保证系统的工作可靠性和安全性，设计了一套监控与分析系统，用于实时监控整个系统的工作状态，通过分析各个环节的监控数据自动完成相应的保护动作。为了验证本设计系统的性能，结合课题设计要求的系统技术指标，对本系统进行了验证性试验。试验内容包括：电容组分流和故障试验；电容温升试验；交、直流回路相互影响试验；交、直流合成大电流试验。试验结果表明，本设计的系统满足设计要求，实现了单匝交流5000A、直流50A的电流合成及平滑控制，为电流互感器直流偏磁的相关实验研究提供了理想的试验装置。
[Abstract]:The interaction between AC and DC systems is becoming more and more obvious because of the mixed operation of AC and DC network. When DC transmission network operates in unipolar geodetic loop mode, The current transformer (CTT) in AC network will produce DC bias magnetization, which will aggravate the oversaturation magnetization of the iron core of CT, which will affect the measurement and protection performance of CT. Therefore, the study can simulate the intersection of CT DC bias environment. DC hybrid current generation system is very important. At present, there are two main ways to realize the AC / DC hybrid current generation system in the current transformer DC bias environment. One is to use the DC current loop and the AC current loop simultaneously and pass through the current transformer respectively. However, this method is only applied to the transmission-type current transformer, because the practical field current transformer is generally installed with the primary conducting rod. Therefore, this method is not suitable for the study of non-piercing current transformers. Another method is to use arbitrary current-generating devices to generate power frequency AC currents containing DC current components. Although the signal generated by this method can be directly connected with the primary conducting rod of the current transformer, the current generated by the method is limited, and the device is large and the manufacturing cost is high. In this paper, a single turn AC / DC synthesizing high current generator based on capacitive isolation is studied. By using capacitive isolation technology, the current characteristics of large capacity non-polarity capacitances are used to resist DC current. The superposition current that flows through AC and DC in the common branch of DC source loop and AC source loop, and the AC current source and DC current source are independent of each other and do not affect each other, thus producing AC and DC composite current; at the same time, In order to ensure the reliability and safety of the system, a monitoring and analysis system is designed, which is used to monitor the working state of the whole system in real time. In order to verify the performance of the design system, the system was tested with the system technical specifications. The test contents include: capacitor shunt and fault test, capacitance temperature rise test, interleaved test, DC circuit interaction test; AC, DC synthesis high current test. The test results show that the designed system meets the design requirements and realizes the current synthesis and smooth control of single turn AC 5000A and DC 50A. It provides an ideal experimental device for the research of DC bias magnetic field of current transformer.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM833

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