| 引用本文: | 胡家为,葛荣尚,尹明铉,等.CT过饱和特性及对过流速断保护的影响[J].电力系统保护与控制,2013,41(16):133-138. |
| HU Jia-wei,GE Rong-shang,YIN Ming-xuan,et al.Characteristics of CT over-saturation and its influence on over-current/instantaneous trip protection[J].Power System Protection and Control,2013,41(16):133-138 |
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| 摘要: |
| 为了提高过流速断保护在 CT 饱和时的可靠性，避免保护拒动，提出了一种保护测量值随短路电流的变化趋势的分析方法。通过分析电流互感器（ CT ）过饱和时的传变特性和输出波形特征，以及继电保护装置的测量性能，说明当故障电流达到数倍于 CT 准确限值电流（即 CT 处于过饱和状态）时， CT 二次电流的特征量随故障电流的增加呈现缓慢单调上升趋势，但保护装置的电流测量值却可能呈现下降趋势，从而引起过流速断保护拒动。分析表明，该分析方法可根据回路参数估算测量值随短路电流的变化趋势，以校验过流速断保护整定值的可靠性，以便采取适当措施避免保护拒动，在工程应用中具有很好的经济效益。 |
| 关键词: 电流互感器 准确限值电流 过饱和 测量值 过流速断保护 整定值 |
| DOI：10.7667/j.issn.1674-3415.2013.16.021 |
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| Characteristics of CT over-saturation and its influence on over-current/instantaneous trip protection |
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HU Jia-wei,GE Rong-shang,YIN Ming-xuan,et al
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| Abstract: |
| In order to improve the reliability of over-current/instantaneous trip protection under CT over-saturation condition and avoid protection operation-failure, this paper presents a useful analysis method of the variation trend of the measurement value of the protection along with short current. The transfer characteristic and output waveform feature as well as measurment performance of relay protection device during CT over-saturation condition are analyzed. It is shown that when fault current is several times larger than CT rated accurate limit primary current (i.e. CT is over-saturated), the characteristic value on the CT secondary side monotonously increases slowly, but the measurement value of the protection devices may decrease along with the increase of the fault current, which causes the failure of the protection. The analysis method calculates the measurement variation trend of the short-circuited current to verify the reliability of the setting values of instantaneous over-current protection, therefore, some proper measures can be taken to avoid the protection failure under this condition. It will have good economy benefits in the real applications. |
| Key words: current transformer(CT) rated accuracy limit primary current over-saturation measurement value instantaneous over-current protection setting values |
