【摘要】 高压直流输电系统的低频谐振会对系统的安全稳定性造成严重影响,为此分析了±1 100 kV特高压直流工程的回路阻抗与频率的关系及系统工频和二次谐振特性。通过PSCAD/EMTDC仿真得出直流系统回路阻抗特性曲线及其谐振点,得出了输电线路长度对谐振点频率的影响,研究了系统在可能引起二次谐振的故障下的暂态过程,并与以往特高压直流工程对比,得出了输电线路长度与低频谐振现象的关系。分析结果表明,输电线路长度是影响直流系统回路阻抗特性的重要因素,线路越长,系统谐振频率越低;2 000 km为高压直流系统易于发生低频谐振的敏感长度。更多还原

【Abstract】 The low frequency resonance of HVDC system may affect the safety and stability of the system operation.This paper studied the relationship between the loop impedance and frequency of ±1100 kV UHVDC project,as well as its secondary frequency resonance.The characteristic curve of loop impedance and its resonance points were calculated by PSCAD/EMTDC simulation.The impact of transmission line length on the frequency of resonance points was proposed.The transient process of system under the fault that might cause secondary frequency resonance was studied,and the relationship between transmission line length and low frequency resonance phenomenon was obtained through the comparison with other UHVDC projects.The analysis results show that the length of transmission line is an important factor of loop impedance characteristics of DC system.The resonant frequency decreases with the increase of transmission line length;and 2000 km is the sensitive length of low frequency resonance of HVDC system.更多还原