提高10kV配电网零序电流保护正确动作率方法
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摘要
广州供电局是国内最早在10 k V系统采用小电阻接地方式的单位,至今已积累了近30年的运行经验。中性点经小电阻接地的配电网采用零序电流保护切除接地故障,若零序电流保护正确动作率低,则会扩大事故范围,降低供电可靠性。本文从零序CT、二次回路接线、保护定值等方面分析零序电流保护不正确动作的原因,提出采用闭环式的专用零序CT、明确零序CT电流外皮地线的安装要求、采用一次加电流方法进行CT变比实测、规范二次回路接线等具体措施,以提高10 k V配电网零序保护正确动作率,供在10 k V配电网中逐步推广中性点经小电阻接地方式的单位参考。
The small resistance grounding mode was earliest used in Guangzhou Power Supply Bureau's 10kV distribution network, which has accumulated nearly 30 years of operating experience. The zero-sequence current protection is used to cut off ground fault. If the correct action rate of the zero-sequence current protection is low, the fault-influenced scope will be enlarged and the reliability of the power supply will be reduced. This paper analyzes the causes of incorrect action of zero sequence current protection from the aspects of zero-sequence CT, secondary circuit wiring, protection setting values and so on. A series of measures have been proposed, such as closed-loop special zero-sequence CT, definition of the installation requirement of zero-sequence CT, measuring the CT ratio by means of adding current, standardizing the secondary circuit wiring and so on. All these specific measures to improve the correct rate of zero-sequence protection in 10kV distribution network, can be referenced by all units which adopts the neutral grounding with small resistance.
The small resistance grounding mode was earliest used in Guangzhou Power Supply Bureau's 10kV distribution network, which has accumulated nearly 30 years of operating experience. The zero-sequence current protection is used to cut off ground fault. If the correct action rate of the zero-sequence current protection is low, the fault-influenced scope will be enlarged and the reliability of the power supply will be reduced. This paper analyzes the causes of incorrect action of zero sequence current protection from the aspects of zero-sequence CT, secondary circuit wiring, protection setting values and so on. A series of measures have been proposed, such as closed-loop special zero-sequence CT, definition of the installation requirement of zero-sequence CT, measuring the CT ratio by means of adding current, standardizing the secondary circuit wiring and so on. All these specific measures to improve the correct rate of zero-sequence protection in 10kV distribution network, can be referenced by all units which adopts the neutral grounding with small resistance.
引文
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[9]付晓奇,徐粮珍,赵宝丽.10k V配网中性点小电阻接地技术应用研究[J].电力系统保护与控制,2010,38(23):227-230.
[10]罗隆福,向博等.10k V小电阻接地系统单相接地故障时的跨步电压仿真与实验研究[J].电力自动化设备,2013,33(6):21-26.
[2]林志超.配电网接地方式与供电可靠性的关联分析[J].广东电力,2015,28(11):87-91.
[3]干耀生,唐庆华,方琼等.城市中压配网中性点小电阻接地方式分析[J].电力系统及其自动化学报,2013,25(3):138-141.
[4]邓申文.中性点接地方式的选取[J].云南电力技术,2007,35(4):52-53.
[5]张静芳.惠州电网小电流接地系统存在问题及解决对策[J].广东电力,2012,25(10):122-125.
[6]电力行业标准.3k V-110k V电网继电保护装置运行整定规程[M].北京:中国电力出版社,2007..
[7]袁勇,李凌.10k V小电阻接地系统接地变压器零序电流保护误动分析[J].华东电力,2003,31(6):31-32.
[8]江文东.10k V小电阻接地系统零序过流定值的探讨[J].电力自动化设备,2002,22(10):73-75.
[9]付晓奇,徐粮珍,赵宝丽.10k V配网中性点小电阻接地技术应用研究[J].电力系统保护与控制,2010,38(23):227-230.
[10]罗隆福,向博等.10k V小电阻接地系统单相接地故障时的跨步电压仿真与实验研究[J].电力自动化设备,2013,33(6):21-26.