摘要
中性点非有效接地的中压配电网中,线路换位不佳、非全相供电以及消弧线圈电压谐振等因素均会导致系统三相电压不对称出现零序电压,威胁电网安全运行。分析了小电流接地系统不对称电压的产生机理,根据电压、电流互换特性研究了不对称电压与注入系统电流间的约束关系,提出了通过注入电流消除不对称电压的有源控制新原理。结合有源补偿装置给出一种可适应系统结构动态变化的不对称电压实用闭环控制方法,从任意幅值和相位的初始注入电流开始,先固定电流幅值改变相位使不对称电压达到最小,再固定相位改变注入电流幅值使不对称电压达到全局最小,即趋近于零。仿真验证表明所提方法可灵活、有效地控制不对称电压,维持电网三相电压平衡。
In the non-solidly grounded distribution network, poor line transposition, open-phase power supply, Petersen coil＇s voltage resonance and other factors lead to the asymmetry of three-phase voltage, giving rise to a zero-sequence voltage in the system harmful to safe operation of the power grid. This paper analyzes the generation mechanism of asymmetrical voltage in a non-solidly grounded system, studies the relationship between the asymmetrical voltage and the current injected into the system according to the exchange characteristic of voltage and current, and proposes a novel active control principle to eliminate asymmetrical voltage by injecting a current into the system. Based on the active compensation device, this paper also proposes a practical closed loop control method to eliminate asymmetrical voltage adapted to the dynamic change of system structures by itself. This method starts with an arbitrary initial injection current. Firstly, fix the injection current amplitude and change its phase to find the phase that makes the asymmetrical voltage minimum. Secondly, fix the phase found in step one and change its amplitude to find the amplitude that makes the asymmetrical voltage globally minimum, or approach zero. The simulation has verified the proposed principle is able to control the asymmetrical voltage flexibly and effectively while maintaining the symmetry of three-phase voltage.
出处
《电力系统自动化》
EI
CSCD
北大核心
2015年第5期115-121,共7页
Automation of Electric Power Systems
基金
国家自然科学基金资助项目(51177096
51477184)
国家高技术研究发展计划(863计划)资助项目(2012AA050213)~~
关键词
非有效接地系统
不对称电压
有源补偿
注入电流
电压控制
non-solidly grounded system
asymmetrical voltage
active compensation
injection current
voltage control
