The work principle of all fiber optical current transducer (AFOCT) was introduced. By analyzing the characteristic of photo-detector's output, a measurement and signal processing scheme based on sine wave modulati...The work principle of all fiber optical current transducer (AFOCT) was introduced. By analyzing the characteristic of photo-detector's output, a measurement and signal processing scheme based on sine wave modulation and demodulation was put forward for eliminating the influence of light intensity change and modulation degree change. A digital signal processing system and a calibration scheme were also advanced. The experimental data show that the mean ratio error is 0.016 74% for direct current and 0.035% for alternating current, and the correlation coefficient of linearity is up to 0.999 982 4, meeting the precision requirement of 0.2 grade. Stability experiments and temperature drift experiments show the AFOCT has a better stable capability.展开更多
基于电网换相型变换器的高压直流输电系统(line commuted converter based high voltage direct current,LCC-HVDC)易发生换相失败,引起整流站交流母线暂态过电压。针对交流暂态过电压威胁送端系统安全运行的问题,提出LCC-HVDC送端交流...基于电网换相型变换器的高压直流输电系统(line commuted converter based high voltage direct current,LCC-HVDC)易发生换相失败,引起整流站交流母线暂态过电压。针对交流暂态过电压威胁送端系统安全运行的问题,提出LCC-HVDC送端交流暂态过电压控制方法。首先,通过分析换相失败下整流站暂态过电压特性,解析了整流站锁相偏差对触发角控制的影响,量化了整流站锁相偏差对整流站交流暂态过电压的影响。然后,基于送受端无功功率平衡关系,提出了补偿整流站不平衡无功的直流电流计算方法。接着,提出了补偿触发角动态误差的触发角指令值计算方法。在此基础上,提出了基于不平衡无功与触发角误差补偿的直流输电系统送端交流暂态过电压控制方法。最后,通过仿真算例证明所提方法对LCC-HVDC送端交流暂态过电压具有显著抑制效果。展开更多
文摘The work principle of all fiber optical current transducer (AFOCT) was introduced. By analyzing the characteristic of photo-detector's output, a measurement and signal processing scheme based on sine wave modulation and demodulation was put forward for eliminating the influence of light intensity change and modulation degree change. A digital signal processing system and a calibration scheme were also advanced. The experimental data show that the mean ratio error is 0.016 74% for direct current and 0.035% for alternating current, and the correlation coefficient of linearity is up to 0.999 982 4, meeting the precision requirement of 0.2 grade. Stability experiments and temperature drift experiments show the AFOCT has a better stable capability.
文摘基于电网换相型变换器的高压直流输电系统(line commuted converter based high voltage direct current,LCC-HVDC)易发生换相失败,引起整流站交流母线暂态过电压。针对交流暂态过电压威胁送端系统安全运行的问题,提出LCC-HVDC送端交流暂态过电压控制方法。首先,通过分析换相失败下整流站暂态过电压特性,解析了整流站锁相偏差对触发角控制的影响,量化了整流站锁相偏差对整流站交流暂态过电压的影响。然后,基于送受端无功功率平衡关系,提出了补偿整流站不平衡无功的直流电流计算方法。接着,提出了补偿触发角动态误差的触发角指令值计算方法。在此基础上,提出了基于不平衡无功与触发角误差补偿的直流输电系统送端交流暂态过电压控制方法。最后,通过仿真算例证明所提方法对LCC-HVDC送端交流暂态过电压具有显著抑制效果。
