【作者】 孙嘉宁；

【导师】 苏建徽；

【作者基本信息】 合肥工业大学 ， 中压电网系统， 2007， 硕士

【摘要】 在三相电网中单相接地故障约占全电网总故障的60%以上,而且相当一部分相间短路故障是由单相接地故障发展而来。谐振也是常见故障之一,尤其在6kV～66kV中性点非有效接地电网中由于单相接地和谐振造成事故更多。常见的针对这些故障的保护产品都存在一定的缺陷,可靠性低、保护效果差,不利于电力系统的安全运行,有必要研究安全性好、可靠性高新的保护方法和实现新保护方法的设备。本论文论述了一种消除弧光接地、消除铁磁性谐振、全范围判别高阻接地故障并提供有效保护的新方法以及实现这种方法的智能综合保护装置。论文的主要创新之处:1)采用新的电压消弧法:用电抗器钳制故障相的电压,破坏产生电弧的机制,实现不受接地电流大小影响的彻底消弧;2)创造性的归纳不接地系统单相接地故障的规律,确立了故障时接地电阻与相电压、中性点位移电压关系的数学模型,设计了相应的计算、判断和保护程序,不论接地电阻值如何变化,都能够准确对高阻接地故障提供有效的保护,将以往难以察觉故障消灭在萌芽状态。3)采用新的消谐方法:直接在一相母线与地之间并接电抗器,破坏谐振点,限制谐振过电压,旁路励磁涌流,实现无死区的全面消谐保护。论文所述的保护装置通过了国家相关检验机构的全面、严格的电气性能和环境型式试验、电磁兼容试验、10kV电网的现场接地故障试验、并在多个变电站10kV电网系统挂网运行等,证实了这种新方法及装置的可靠性与实用性。该装置已获国家级新产品鉴定,鉴定结论为:“装置的设计思路新颖,保护性能良好,其消弧、消谐的方法、对高阻接地故障的判别和保护处于国内领先水平”,“可以投入批量生产”。更多还原

【Abstract】 In a traditional three-phase power grid, single-phase ground fault (SPGF) not only directly results in more than 60% of network breakdowns, but also leads to a significant portion of phase-to-phase faults; and hence the SPGF also indirectly causes some of the other approximately 40% of breakdowns. Resonance is another common fault that breaks down a grid. The total percentage of breakdowns due to a SPGF or a resonance, in a 6kV-66kV, neutral-point, ineffective grounding power grid, is even higher than those in other types of grid systems. Common products for fault protection suffer from low reliability, ineffective protection, or are unfavorable to safe operation of a power grid. It is imperative to develop new techniques and protection systems that are highly reliable and safe, in eliminating or reducing power gird’s breakdowns.In this thesis, a new technique is presented for eliminating ground fault due to electric arc, and resonance due to ferromagnetic fields; and for predicting, detecting and protecting against a high-resistance ground fault (HRGF) in the entire power grid. A comprehensive intelligence device that implements the technique is also developed.The major innovation in this thesis includes: 1) developing a new voltage method that eliminates the electric arc 100% by connecting in parallel a reactance between a faulty phase and the ground, clamping down on the voltage of a faulty phase, cutting off arc paths, and 1 diverting all faulty currents; 2) conducting a novel, fault pattern recognition, and designing/coding a computer program to automate an accurate monitoring and protection against possible HRGF; and 3) using a new method to suppress resonance by inserting in parallel a reactance between the generator of the one responsible phase and the ground, destroying resonance points, suppressing over-voltage from a resonance, diverting excited currents, and hence realizing a no-dead-ends, complete protection against resonance.Our protection device has passed a series of tests conducted by relevant government inspection agencies. These tests include an extensive and rigorous electrical and modeling performance test, an electromagnetic compatibility test, a 10kV in situ ground fault detection and protection experiment, and an extended practical running of our equipment in a 10kV three-phase power grid. The new technique and device are shown to be reliable and practical. A national-level new product appraisal was completed and a certification was granted. It is stated in the certificate that "1) the design is novel; 2) the protection is good; 3) the methods for eliminating electric arc, resonance, and for monitoring, detecting and protecting against HRGF are among the state of the art in China; and 4) a mass production of the intelligent protection device is permitted."更多还原