摘要
零序电流差动保护对接地故障灵敏度高,动作电流与变压器调压分接头无关,受励磁涌流影响小,原理简单等优点,在超高压自耦变压器保护上得到广泛应用。但零序电流差动保护由于反应自耦变压器三侧零序电流的相量和而动作,受电流互感器饱和影响较大,不易整定,在区外故障切除时常常导致保护的误动。据此提出"基于零序电流的超高压自耦变压器相位比较纵联保护方案"。该方案比较自耦变压器两侧保护处零序电流相位,根据相位相同或相反作为故障判据来区分自耦变压器内部故障或外部故障。动模试验数据和数字仿真验证结果表明,该方案具有对超高压自耦变压器接地故障灵敏度高,选择性好,能够正确反应自耦变压器各种轻微匝间故障,保护判据均不受零序电流非周期分量和故障侧电流互感器(CT)饱和深度的影响等优点。
Zero-sequence current differential protection for grounding fault has the advantages of high sensitivity, action current＇s independence with transformer tap joint, small influence from inrush current, and principle simplicity. It is widely used in the area of UHV autotransformer protection. However, the zero-sequence current differential protection operates due to responding to the phase sum of zero sequence current in three sides of autotransformer, which is badly influenced by the saturation of current transformer and hard to set the threshold. In the external fault, it will lead to mal-operation. Based on this, a new auto-transformer pilot protection scheme based on the zero-sequence current phase comparison is proposed. The fault direction can be determined by comparing the phase shift between zero sequence current of high voltage side, medium voltage side and the reference current. So the internal fault and external fault can be discriminated. The results of dynamic simulation experiment and digital simulation shows that the proposed method can detect turn-to-ground and turn-to-turn fault with high sensitivity and good selectivity. Besides, the protection criterion is not affected both by the non-periodic component of zero-sequence current and saturation level of fault-side current transformer （CT）.
出处
《电力系统保护与控制》
EI
CSCD
北大核心
2014年第16期59-65,共7页
Power System Protection and Control
基金
国家自然科学基金项目(51267018)
新疆维吾尔自治区自然科学基金项目(2010211A13)~~
关键词
自耦变压器
接地故障
零序电流
相位比较
匝间故障
CT饱和
非周期分量
auto-transformer
turn-to-ground fault
zero-sequence current
phase comparison
turn-to-turn fault
saturation of currenttransformer
non-periodic component
