We propose a modular multilevel converter(MMC)based three-phase four-wire(3P4W)split capacitor distribution static synchronous compensator(DSTATCOM),aiming at compensating unbalanced and reactive load currents.Due to ...We propose a modular multilevel converter(MMC)based three-phase four-wire(3P4W)split capacitor distribution static synchronous compensator(DSTATCOM),aiming at compensating unbalanced and reactive load currents.Due to the zero-sequence current compensation,the circulating current char-acteristics of 3P4W MMC-DSTATCOM are different from conventional MMCs.Moreover,the distinct working principle of IMMC would affect the features of split capacitor voltage.The decoupled positive-,negative-and zero-sequence second-order and DC components of the circulating current are deduced explicitly.Two proportional-integral controllers with dual dq transformation are employed to suppress the positive-and negative-sequence components of second-order circulating current,while quasi proportional-resonance controller is designed to eliminate the zero-sequence component.Besides,the phenomenon of the unbalanced split capacitor voltages is revealed,and fast-tracking balancing method by controlling zero-sequence current flowing through the split capacitors is provided.Digital simulation results verify the accuracy of the analysis and the feasibility of the suppression methods.展开更多
针对三相四线制低压配电网不平衡非线性负载的电能质量问题,提出采用矢量谐振控制器对电容分离型有源电力滤波器(Active Power Filter,APF)进行指定次数谐波控制方案。在αβγ坐标系下对电容分离型APF进行建模,省去了在dq坐标系下的电...针对三相四线制低压配电网不平衡非线性负载的电能质量问题,提出采用矢量谐振控制器对电容分离型有源电力滤波器(Active Power Filter,APF)进行指定次数谐波控制方案。在αβγ坐标系下对电容分离型APF进行建模,省去了在dq坐标系下的电流交叉解耦环节。比例谐振控制器应用在APF闭环控制系统时,存在各次谐振点附近谐振尖峰影响闭环控制系统稳定性和补偿精度的问题,采用矢量谐振控制器实现指定次数谐波跟踪控制,其分子零点与控制对象的极点抵消,实现控制系统降阶,提高了控制性能。仿真结果表明,所提控制方法在针对指定次数谐波补偿方面有着良好效果,其三相不平衡被抑制,直流侧电容电压得到均衡控制,证明了所提方法有效性。展开更多
An error correction technique to achieve a 14-bit successive approximation register analog-to-digital converter(SAR ADC) is proposed. A tunable split capacitor is designed to eliminate the mismatches caused by parasit...An error correction technique to achieve a 14-bit successive approximation register analog-to-digital converter(SAR ADC) is proposed. A tunable split capacitor is designed to eliminate the mismatches caused by parasitic capacitors. The linearity error of capacitor array caused by process mismatch is calibrated by a novel calibration capacitor array that can improve the sampling rate. The dual-comparator topology ensures both the speed and precision of the ADC. The simulation results show that the SAR ADC after calibration achieves 83.07 dB SNDR and 13.5 bit ENOB at 500 kilosamples/s.展开更多
基金This work was supported in part by the National Natural Science Foundation of China(No.51807073).
文摘We propose a modular multilevel converter(MMC)based three-phase four-wire(3P4W)split capacitor distribution static synchronous compensator(DSTATCOM),aiming at compensating unbalanced and reactive load currents.Due to the zero-sequence current compensation,the circulating current char-acteristics of 3P4W MMC-DSTATCOM are different from conventional MMCs.Moreover,the distinct working principle of IMMC would affect the features of split capacitor voltage.The decoupled positive-,negative-and zero-sequence second-order and DC components of the circulating current are deduced explicitly.Two proportional-integral controllers with dual dq transformation are employed to suppress the positive-and negative-sequence components of second-order circulating current,while quasi proportional-resonance controller is designed to eliminate the zero-sequence component.Besides,the phenomenon of the unbalanced split capacitor voltages is revealed,and fast-tracking balancing method by controlling zero-sequence current flowing through the split capacitors is provided.Digital simulation results verify the accuracy of the analysis and the feasibility of the suppression methods.
文摘针对三相四线制低压配电网不平衡非线性负载的电能质量问题,提出采用矢量谐振控制器对电容分离型有源电力滤波器(Active Power Filter,APF)进行指定次数谐波控制方案。在αβγ坐标系下对电容分离型APF进行建模,省去了在dq坐标系下的电流交叉解耦环节。比例谐振控制器应用在APF闭环控制系统时,存在各次谐振点附近谐振尖峰影响闭环控制系统稳定性和补偿精度的问题,采用矢量谐振控制器实现指定次数谐波跟踪控制,其分子零点与控制对象的极点抵消,实现控制系统降阶,提高了控制性能。仿真结果表明,所提控制方法在针对指定次数谐波补偿方面有着良好效果,其三相不平衡被抑制,直流侧电容电压得到均衡控制,证明了所提方法有效性。
基金Supported by National Science and Technology Major Project of China(No.2012ZX03004008)
文摘An error correction technique to achieve a 14-bit successive approximation register analog-to-digital converter(SAR ADC) is proposed. A tunable split capacitor is designed to eliminate the mismatches caused by parasitic capacitors. The linearity error of capacitor array caused by process mismatch is calibrated by a novel calibration capacitor array that can improve the sampling rate. The dual-comparator topology ensures both the speed and precision of the ADC. The simulation results show that the SAR ADC after calibration achieves 83.07 dB SNDR and 13.5 bit ENOB at 500 kilosamples/s.
