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汽轮发电机定子绕组缺线圈运行时的负序过负荷保护分析
张琦雪1, 冯桂青2, 陈 俊1, 严 伟1, 沈全荣1
1.南京南瑞继保电气有限公司,江苏 南京 211102;2.深圳能源集团股份有限公司,广东 深圳 518031
摘要:
一台缺线圈运行的汽轮发电机,实测有不超过6.2 p.u. 的负序电流。为防止负序过电流损伤转子铁芯,需要定量评估电枢电流的影响。假设在故障相上增加一个“叠加绕组”,采用叠加原理,分析并计算出电枢反应的反转基波磁动势与正序、负序电流之间的定量关系,进一步计算得到等效的负序电流。分析表明因绕组不对称,负序电流和正序电流都会产生反转的基波磁动势。对于这台发电机的负序过负荷保护,可适当降低长期允许负序电流值I2∞至8.5 p.u.,不必降低承受负序电流能力的常数I 2 2 t。
关键词:  汽轮发电机  定子  负序过电流  过负荷保护  继电保护  定子绕组  叠加原理
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Analysis of negative-sequence overload relay protection for turbine generator operating with asymmetrical stator windings
ZHANG Qixue1, FENG Guiqing2, CHEN Jun1, YAN Wei1, SHEN Quanrong1
1.NARI-Relays Electric Co.,Ltd.,Nanjing 211102,China;2.Shenzhen Energy Group Co.,Ltd.,Shenzhen 518031,China
Abstract:
A turbine generator temporarily operating with asymmetrical stator windings has measured negative-sequence current less than 6.2 %. The effect of asymmetrical armature currents should be quantitatively evaluated to avoid the rotor damage caused by the negative-sequence overcurrent. A hypothetical superposing winding is added to the faulty phase and the superposition principle is used to analyze the quantitative relation between the contra-rotational fundamental MMF(Magnetic Motive Force) and the positive/negative sequence current. The equivalent negative-sequence current is then calculated. Analysis shows that,both negative and positive sequence currents contain MMF due to the asymmetrical stator windings. It is suggested that the I2∞ of the negative sequence overload relay protection for this generator be reduced to 8.5 p.u. while its I22t kept.
Key words:  steam turbine generator  stators  negative-sequence overcurrent  overload relay protection  relay protection  superposition principle

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