摘要
运用状态空间建模方法研究了目前国内广泛关注的零序直流选择性漏电保护中电网对地分布电容对支路检测信号零序直流选择特性的影响。首先根据整流管的工作特性建立了任意工频周期内检测电流的电路模型,用状态变量法推导出各检测电流的数学表达式;然后用谐波分析法对各检测电流进行谐波分解和幅值计算,并得到其波形。结果表明:正常取值范围内的分布地容对分支检测信号的选择特性影响很小,并且与不考虑电容影响时一样,当漏电阻值降到3.3kΩ以下时,其选择特性更加显著。
By use of state space modeling approach the impact of distributed capacitance between transmission line and ground on zero-sequence DC selective characteristic of branch detection signal in zero-sequence selective leakage protection to which attentions are widely paid is researched. At first, according to working characteristic of rectifier tube in measuring circuit of power network leakage protection system, the circuit model of detection current in arbitrary power frequency period is built, and the mathematical expressions for detected currents are derived by state variable method; then by use of harmonic analysis method, the harmonic decomposition and amplitude calculation of detected currents are carried out and corresponding waveforms are obtained. Calculation results show that the impact of normal distributed capacitance between transmission line and ground on selective characteristics of branch detection information is very slight, so it can be neglected; and the selective characteristic of branch detection information becomes more evident while the value of leakage resistance is changed to less than 3.3kΩ.
出处
《电网技术》
EI
CSCD
北大核心
2008年第15期94-98,共5页
Power System Technology
关键词
状态空间建模
零序直流
谐波分析
分布电容
选择特性
state-space modeling： zero sequence DC
harmonic analysis
distributed capacitance
selective nature
