2011年第5卷第5期 2011. Vol.5, No.5
南方电网技术
SOUTHERN POWER SYSTEM TECHNOLOGY
文章编号：1674-0629(2011)05-0077-04
中图分类号：TM712;TM744
研究与分析 Study & Analysis 文献标志码：A
变压器零序差动保护制动电流算法探讨
罗云照1，陈朝晖2
（1.中国南方电网超高压输电公司，广州510620；2.中图南方电网电力调度控制中心，广州510623）
摘要：在制定云广直流工程换流变压器保护计划时，发现采用基于高压侧相电流之差原理的变压露零序差动保护制动电流算法结果有同题。通过整定计算实例和理论分析，指出该“新算法”用于换流变压器等单侧电源中性点直接接地系缺时必然会产生误动；用于高压系统电厂双绕组升压变压器这类双侧电源系统时，所算得的零序制动电流比采用传统算法
时的制动电流更小，区外单相接地故障制动效采比传统零序差动保护差。此，该“新算法”有必要加以改进。关键调：双绕组变压器；零序差动保护；制动电流
OntheAlgorithmofResistingCurrentofTransformer'sZero-sequence
DifferentialProtection LUO Yunzhao', CHEN Zhaohui?
(1. Operation & Technology Department of CSG EHV Power Transmission Company, Guangzhou 510620, China
2.CSG Power Dispatching and Control Centre,Guangzhou 510623, China)
Abstract: When setting down the converter transformer protection scheme of Yunnan-Guangdong DC project, a poor result is found in the resisting current from a new algorithm based on the principle of phase-current differeatial of transformer's zero-sequence differential protection at the high volage side. Through example calculation and theoretical analysis, this paper points out that the results of the new algorithm will lead to malfunction as it is used in the single side power source system with neutral-point directly grounding such as converter transformer protection, and also lead to a smaller resisting current than that of the traditional algorithm as it is used in the double side power source system such as double-windings step-up transformer in high voltage power plant, and the zero-sequence resisting current from the new algorithm is smaller than that from the traditional aligorithm, resulting in a weaker effect
for treating the single phase grounding fault beyond protection zone. Therefore, the new algorithm should be improved further Key words: double-windings transformer; zero-sequence differential protection; resisting current
变压器零序差动保护作为变压器比例制动差动保护的补充，其安全性至关重要(-4)。传统的变压器零序差动保护制动电流通常取相电流的最大模值。文献[5]提出了一种基于高压侧相电流之差原理的制动电流I新公式，在区内、外相间短路时制动能力特强而区内单相接地短路时动作灵敏度高，被认为是超高压系统变压器零序差动保护抗电流互感器饱和防误动的有效措施。部分变压器保护装置采用了这种制动电流新公式，并在多个交流系统工程中投入应用[6]。
云广直流工程换流变压器保护原计划采用此种零序差动保护原理的制动电流I新公式7，但在整定计算过程中发现，该公式的计算结果有问题，并在云广直流工程中重新采用了传统的零序差动保护
万方数据
制动电流的计算公式。
本文通过程序计算结果和理论分析，对文献[5 的制动电流Ies新公式进行了探讨。
1零序差动保护动作方程及整定 1.1传统变压器零序差动保护
零序差动保护接线图见图1，以Y0/△-11接线的双绕组变压器为例，传统零序差动保护的差动电流Iop和制动电流Ires如式（1）和式（2）所示，
lep=|3/0% +3/0v] I =max(/uy,/v,/w) 。
(1)(2)
式中：31%为变压器中性点的三倍零序电流；31%为变压器YO侧端部经零序电流过滤器直接得到的零