级联型混合直流系统受端的模块化多电平换流器高压直流系统(modular multilevel converter high voltage direct current,MMC-HVDC)和电网换相换流器高压直流系统(line commutated converter high voltage direct current,LCC-HVDC)会...级联型混合直流系统受端的模块化多电平换流器高压直流系统(modular multilevel converter high voltage direct current,MMC-HVDC)和电网换相换流器高压直流系统(line commutated converter high voltage direct current,LCC-HVDC)会因馈入点电气距离较近而存在强相互作用关系。为明确级联型混合直流馈入系统中MMC-HVDC对LCC-HVDC系统强度的影响,提出考虑幅值和相位的MMC等效电流源的简化等效方法,基于所提MMC等效原理将级联型混合直流馈入系统等效成单馈入LCC-HVDC系统,分析等效单馈入系统的参数计算方法,并提出等效单馈入短路比评估指标。最后通过该指标分析归纳了不同控制方式、不同电气距离下等效单馈入系统的系统强度变化情况,即为MMC-HVDC对LCC-HVDC系统强度的影响规律。机理分析和基于PSCDAD/EMTDC、MATLAB的仿真结果表明,所提等效方法具有有效性且所提指标能很好地反应MMC-HVDC对LCC-HVDC系统强度的影响。展开更多
This work gives an analytical theory of the signal-to-thermal-noise ratio (SNR) of classical Hall plates with four contacts at small magnetic field. In contrast to previous works, the symmetry of the Hall plates is re...This work gives an analytical theory of the signal-to-thermal-noise ratio (SNR) of classical Hall plates with four contacts at small magnetic field. In contrast to previous works, the symmetry of the Hall plates is reduced to only a single mirror axis, whereby the average of potentials of the two output contacts off this mirror axis differs from the average of potentials at the two supply contacts on the mirror axis, i.e. the output common mode differs from 50%. Surprisingly, at fixed power dissipated in the Hall plate, the maximum achievable SNR is only 9% smaller for output common modes of 30% and 70% when compared to the overall optimum at output common modes of 50%. The theory is applied to Vertical Hall effect devices with three contacts on the top surface and one contact being the buried layer in a silicon BiCMOS process. Geometries are found with large contacts and only a moderate loss in SNR.展开更多
针对过往多馈入直流(multi-infeed line commutated converter based high voltage direct current,MIDC)系统强度指标不能准确反映静态电压稳定的问题,该文研究计及MIDC系统静态电压稳定的强度指标定义方法。首先,在推导MIDC系统潮流...针对过往多馈入直流(multi-infeed line commutated converter based high voltage direct current,MIDC)系统强度指标不能准确反映静态电压稳定的问题,该文研究计及MIDC系统静态电压稳定的强度指标定义方法。首先,在推导MIDC系统潮流分析模型的基础上,定义基于多馈入交互作用因子的等值耦合导纳的概念,等值耦合导纳可定量反映MIDC系统中其余直流子系统对被研究直流子系统的影响;并建立基于等值耦合导纳的MIDC系统单端口等值模型。其次,基于建立的MIDC系统单端口等值模型,提出一种能够准确衡量MIDC系统静态电压稳定的多馈入综合短路比(multi-infeed integrated short circuit ratio,MISCR)强度指标。最后,在不同直流功率增长场景和控制方式组合下的算例分析结果表明,所提MISCR指标比过往强度指标更能准确地衡量MIDC系统的静态电压稳定性。展开更多
文摘级联型混合直流系统受端的模块化多电平换流器高压直流系统(modular multilevel converter high voltage direct current,MMC-HVDC)和电网换相换流器高压直流系统(line commutated converter high voltage direct current,LCC-HVDC)会因馈入点电气距离较近而存在强相互作用关系。为明确级联型混合直流馈入系统中MMC-HVDC对LCC-HVDC系统强度的影响,提出考虑幅值和相位的MMC等效电流源的简化等效方法,基于所提MMC等效原理将级联型混合直流馈入系统等效成单馈入LCC-HVDC系统,分析等效单馈入系统的参数计算方法,并提出等效单馈入短路比评估指标。最后通过该指标分析归纳了不同控制方式、不同电气距离下等效单馈入系统的系统强度变化情况,即为MMC-HVDC对LCC-HVDC系统强度的影响规律。机理分析和基于PSCDAD/EMTDC、MATLAB的仿真结果表明,所提等效方法具有有效性且所提指标能很好地反应MMC-HVDC对LCC-HVDC系统强度的影响。
文摘This work gives an analytical theory of the signal-to-thermal-noise ratio (SNR) of classical Hall plates with four contacts at small magnetic field. In contrast to previous works, the symmetry of the Hall plates is reduced to only a single mirror axis, whereby the average of potentials of the two output contacts off this mirror axis differs from the average of potentials at the two supply contacts on the mirror axis, i.e. the output common mode differs from 50%. Surprisingly, at fixed power dissipated in the Hall plate, the maximum achievable SNR is only 9% smaller for output common modes of 30% and 70% when compared to the overall optimum at output common modes of 50%. The theory is applied to Vertical Hall effect devices with three contacts on the top surface and one contact being the buried layer in a silicon BiCMOS process. Geometries are found with large contacts and only a moderate loss in SNR.
文摘针对过往多馈入直流(multi-infeed line commutated converter based high voltage direct current,MIDC)系统强度指标不能准确反映静态电压稳定的问题,该文研究计及MIDC系统静态电压稳定的强度指标定义方法。首先,在推导MIDC系统潮流分析模型的基础上,定义基于多馈入交互作用因子的等值耦合导纳的概念,等值耦合导纳可定量反映MIDC系统中其余直流子系统对被研究直流子系统的影响;并建立基于等值耦合导纳的MIDC系统单端口等值模型。其次,基于建立的MIDC系统单端口等值模型,提出一种能够准确衡量MIDC系统静态电压稳定的多馈入综合短路比(multi-infeed integrated short circuit ratio,MISCR)强度指标。最后,在不同直流功率增长场景和控制方式组合下的算例分析结果表明,所提MISCR指标比过往强度指标更能准确地衡量MIDC系统的静态电压稳定性。
