【作者】 刘召；

【导师】 印永华； 张辉； 熊敏；

【作者基本信息】 中国电力科学研究院 ， 电力系统及其自动化， 2007， 硕士

【摘要】 随着我国大量直流输电工程的建设和投入运行,单极大地回线运行方式下,接地极入地电流对附近交流系统中性点接地变压器的影响问题,已引起电力行业的高度重视。变压器中性点串电容、变压器中性点串电阻、直流电位补偿法和交流线上串电容都能抑制变压器中性点的直流电流。针对变压器中性点流过较大的直流电流和交流线路发生故障时流过变压器中性点较大的短路电流的情况,本论文采用在变压器中性点串电容的方法开展变压器中性点直流电流抑制装置的研制和试验研究工作。论文以抑制岭澳和大亚湾核电站变压器中性点直流电流的装置研制项目为依托,对变压器中性点直流电流抑制装置的原理、构成和试验方法进行了研究,对装置的主要功能进行研究并通过科学的试验方法来验证装置能否满足这些功能,并对试验中发现的技术问题进行分析,提出解决缺陷的方法和措施。通过单项试验、模拟运行试验和大电流试验完善了装置的技术性能。论文主要研究内容如下:1)从理论上提出变压器中性点直流电流抑制装置应满足的技术性能要求,详细讨论了变压器中性点直流电流抑制装置的晶闸管配置、限流电感线圈电阻值的确定、维持回路的设计及具体参数的选择和快速开关闭合时间及通流容量要求等等。2)研究需要考核的主要技术指标,确定试验方法,制定试验方案,包括各单项试验、模拟运行试验和大电流试验等试验方案。3)在对装置元器件参数进行理论分析的基础上,对快速开关、限流电感、晶闸管和维持回路等主要元器件进行单项试验和模拟运行试验,测定各元器件性能,分析试验结果,优化了元器件的具体参数。4)为模拟本装置装设于变压器中性点后可能遇到的严重故障情况下流过装置的电流和加在装置两端的电压,对装置进行了多次大电流冲击试验并分析试验结果。对装置内流过的电流波形进行了分析,针对所暴露出的问题,改进了装置的不合理部分,提高了装置的可靠性。更多还原

【Abstract】 With the construction and operation of many HVDC projects in China, under monopole operation mode with earth return, the impact of grounding current passed through grounding pole on the nearby transformers with earthed neutral point in AC system has been highly regarded by electronic power industry.Putting a capacitor in series between transformer neutrals, putting a resister in series between transformer neutrals, the way of DC electric potential compensation and putting a capacitor in series on AC transmission system are all measures to restrain DC. Considering that larger DC current flows through transformer neutrals and that when fault occurs larger fault current flows through transformer neutrals, transformer neutral DC current bloking device has been developed and tested by the way of putting a capacitor in series between transformer neutrals.On the base of the project to restrain the DC current flowed through transformer neutrals in LING AO and DA YA BAY nuclear power station, the principle, structure and test plan of transformer neutral DC current bloking device are studied in the paper. The main functions of the device are researched and the device is tested to meet these functions. Technology problems that has been found in experiments are analyzed, also the methods and measures that can resolve the flaw are proposed. Through monomial tests, simulative operation tests and high-current tests, the device has been improved.The paper’s main contents are as follows:1) The technology and performance requirements that transformer neutral DC current bloking device should meet are proposed in the paper. It is detailedly discussed about transistor collocation, current limit inductance winding’s resistance, maintained loop’s design and its resistance, breaker’s close time and its capability.2) The main technology indexes are studied . The way of test is confirmed and the schemes are set down. These include monomial test schemes, simulative operation test schemes and high-current test schemes.3)On the base of theoretical analysis to device’s elements, the monomial tests and simulative operation tests are made to the main elements including fast bypass breaker, current limit inductance, transistor and maintained loop. The capabilities of each device’s elements are mensurated, the results of test are analyzed and the parameters of each device’s element are optimized.4) For simulating the fault current flowing through the device and the voltage added on the device when transformer neutral DC current bloking device was installed at transformer neutrals, high-current experiments are carried out. The waves of current flowing through the device are analyzed. To the problems occurred in the test, the unreasonable parts of the device are mended for improving its reliability.更多还原