独立励磁直流发电系统输出电能质量取决于其电压控制性能。然而基于比例积分调节的电压闭环控制输出响应慢、恢复波形超调大。此外,基于电容能量控制(capacitor energy control,CEC)的方法外环积分系数与负载电流反馈相矛盾,影响输出电...独立励磁直流发电系统输出电能质量取决于其电压控制性能。然而基于比例积分调节的电压闭环控制输出响应慢、恢复波形超调大。此外,基于电容能量控制(capacitor energy control,CEC)的方法外环积分系数与负载电流反馈相矛盾,影响输出电压稳态精度。针对以上问题,该文基于CEC提出一种外环单比例调节控制策略。首先,外环仅采用比例控制避免了电容储能误差积分引起系统超调的问题;其次,基于电容电荷平衡控制采用动态过程线性控制到非线性控制的转换思想计算励磁电流最快线性上升斜率并确定外环比例系数,使得系统动态响应最快;最后,通过实验验证所提控制策略的有效性。结果表明,所提控制策略动态性能优良、稳态电压精度高。展开更多
静止无功发生器(Static Var Generator,SVG)多采用双闭环PI控制。这种控制方式下,SVG启动瞬间会产生过大的冲击电流。分析了冲击电流产生的原因,在此基础上,设计直流电压逐步升高和电容能量外环控制相结合的方法,以降低冲击电流。通过Ma...静止无功发生器(Static Var Generator,SVG)多采用双闭环PI控制。这种控制方式下,SVG启动瞬间会产生过大的冲击电流。分析了冲击电流产生的原因,在此基础上,设计直流电压逐步升高和电容能量外环控制相结合的方法,以降低冲击电流。通过Matlab/Simulink仿真对此方法进行仿真研究。最后,通过研制的SVG实验平台,对设计的方法进行实验验证。仿真和实验结果表明,该方法能够有效抑制启动冲击电流,SVG装置能够精确地补偿负载所产生的无功功率。展开更多
In order to review storage performance of the electric double layer capacitor （EDLC） in microgrid applications, charging time and storage efficiency issues are mainly studied aiming at three different charging modes...In order to review storage performance of the electric double layer capacitor （EDLC） in microgrid applications, charging time and storage efficiency issues are mainly studied aiming at three different charging modes, including the constant voltage charging mode （CVCM）, the constant current charging mode （CCCM） and the constant power charging mode （CPCM）, based on the practical EDLC product. Numerical calculation methods are presented for different charging modes, and the charging efficiency is also reviewed with strict mathematical deductions, which is validated to be accurate enough and applicable through a simple case with the PV/EDLC system illustration. Finally, trade-off problems between charging time and energy loss are also studied. Research results show that the CPCM is more suitable for microgrid networks compared with the traditional constant-voltage and constant-current charging modes. The hybrid charging method is recommended to save energy and keep high efficiency relatively at the same time. However, how to manage the combination percentage of different charging modes in a reasonable way should be dealt with according to the practical requirements.展开更多
Anodic electrodes with the mixture of hydrogen storage alloys and different contents of Co3O4（2%,4%,6% and 8%,mass fraction） powders were made.The effects of Co3O4 on the electrochemical performance of the alloy ele...Anodic electrodes with the mixture of hydrogen storage alloys and different contents of Co3O4（2%,4%,6% and 8%,mass fraction） powders were made.The effects of Co3O4 on the electrochemical performance of the alloy electrodes were studied.The constant charge-discharge tests show that the discharge capacity of alloy electrodes with Co3O4 significantly increases,and the maximum discharge capacities of electrodes with 2%,4%,6% and 8% Co3O4 are higher than the electrode with no Co3O4 by 0.83%,4.86%,7.18% and 9.21%,accordingly.Linear polarization（LP） and electrochemical impedance spectroscopy（EIS） tests suggest that charge-transfer resistance decreases by the addition of Co3O4.Cyclic voltammogram（CV）,scanning electron microscopy（SEM） and energy dispersive spectrum（EDS） tests indicate that Co3O4 can partly dissolve and experience a reversible oxidation-reduction process of Co to Co（OH）2,leading to the improvement in the electrochemical performance of hydrogen storage alloy.展开更多
文摘独立励磁直流发电系统输出电能质量取决于其电压控制性能。然而基于比例积分调节的电压闭环控制输出响应慢、恢复波形超调大。此外,基于电容能量控制(capacitor energy control,CEC)的方法外环积分系数与负载电流反馈相矛盾,影响输出电压稳态精度。针对以上问题,该文基于CEC提出一种外环单比例调节控制策略。首先,外环仅采用比例控制避免了电容储能误差积分引起系统超调的问题;其次,基于电容电荷平衡控制采用动态过程线性控制到非线性控制的转换思想计算励磁电流最快线性上升斜率并确定外环比例系数,使得系统动态响应最快;最后,通过实验验证所提控制策略的有效性。结果表明,所提控制策略动态性能优良、稳态电压精度高。
文摘静止无功发生器(Static Var Generator,SVG)多采用双闭环PI控制。这种控制方式下,SVG启动瞬间会产生过大的冲击电流。分析了冲击电流产生的原因,在此基础上,设计直流电压逐步升高和电容能量外环控制相结合的方法,以降低冲击电流。通过Matlab/Simulink仿真对此方法进行仿真研究。最后,通过研制的SVG实验平台,对设计的方法进行实验验证。仿真和实验结果表明,该方法能够有效抑制启动冲击电流,SVG装置能够精确地补偿负载所产生的无功功率。
基金The National Natural Science Foundation of China (No.50907010)Ph.D.Programs Foundation of Ministry of Education of China(No.20070286047)Scientific Innovation Foundation for Youngsters of CSEE
文摘In order to review storage performance of the electric double layer capacitor （EDLC） in microgrid applications, charging time and storage efficiency issues are mainly studied aiming at three different charging modes, including the constant voltage charging mode （CVCM）, the constant current charging mode （CCCM） and the constant power charging mode （CPCM）, based on the practical EDLC product. Numerical calculation methods are presented for different charging modes, and the charging efficiency is also reviewed with strict mathematical deductions, which is validated to be accurate enough and applicable through a simple case with the PV/EDLC system illustration. Finally, trade-off problems between charging time and energy loss are also studied. Research results show that the CPCM is more suitable for microgrid networks compared with the traditional constant-voltage and constant-current charging modes. The hybrid charging method is recommended to save energy and keep high efficiency relatively at the same time. However, how to manage the combination percentage of different charging modes in a reasonable way should be dealt with according to the practical requirements.
基金Projects(21071153,20976198)supported by the National Natural Science Foundation of China
文摘Anodic electrodes with the mixture of hydrogen storage alloys and different contents of Co3O4（2%,4%,6% and 8%,mass fraction） powders were made.The effects of Co3O4 on the electrochemical performance of the alloy electrodes were studied.The constant charge-discharge tests show that the discharge capacity of alloy electrodes with Co3O4 significantly increases,and the maximum discharge capacities of electrodes with 2%,4%,6% and 8% Co3O4 are higher than the electrode with no Co3O4 by 0.83%,4.86%,7.18% and 9.21%,accordingly.Linear polarization（LP） and electrochemical impedance spectroscopy（EIS） tests suggest that charge-transfer resistance decreases by the addition of Co3O4.Cyclic voltammogram（CV）,scanning electron microscopy（SEM） and energy dispersive spectrum（EDS） tests indicate that Co3O4 can partly dissolve and experience a reversible oxidation-reduction process of Co to Co（OH）2,leading to the improvement in the electrochemical performance of hydrogen storage alloy.
