An intelligent power factor correction scheme is presented for three phase low power factor loads. This new scheme is able to perform individual phase sensing of parameters by monitoring at all times to sense a change...An intelligent power factor correction scheme is presented for three phase low power factor loads. This new scheme is able to perform individual phase sensing of parameters by monitoring at all times to sense a change in system parameters and affects individual phase correction by applying the exact amount of reactive components needed for each phase, and can also reduce negative sequence current caused by the load to improve system balance. An optimization criterion is used for the proper calculation of reactive power steps in a power compensation installation of capacitor banks. The criterion is enabled by sampling measurements performed on the electrical plant examined within specific interval of time.展开更多
Mathematical modelling for power DC/DC converters is a historical problem accompanying DC/DC conversion technology since 1940’s. The traditional mathematical modelling is not available for complex structure converter...Mathematical modelling for power DC/DC converters is a historical problem accompanying DC/DC conversion technology since 1940’s. The traditional mathematical modelling is not available for complex structure converters since the differential equation order increases very high. We have to search other way to establish mathematical modelling for power DC/DC converters.We have theoretically defined a new concept-Energy Factor （EF） in this paper and researched the relations between EF and the mathematical modelling for power DC/DC converters. EF is a new concept in power DC/DC conversion technology, which thoroughly differs from the traditional concepts such as power factor （PF）, power transfer efficiency （η）, total harmonic distortion （THD） and ripple factor （RF）. EF and the subsequential EFV (and EFVD) can illustrate the system stability, reference response and interference recovery. This investigation is very helpful for system design and DC/DC converters characteristics foreseeing. Two DC/DC converters: Buck converter and Super-Lift Luo-Converter as the samples are analysed in this paper to demonstrate the applications of EF, EFV (and EFVD), PE, SE, VE （and VED）, time constant τ and damping time constant τd.展开更多
Based on a neutral point diode clamped eight-switch configuration, a general mathematical model of single phase bi-directional three-level (TL) rectifiers is built by proposing two equivalent TL arms for topology deri...Based on a neutral point diode clamped eight-switch configuration, a general mathematical model of single phase bi-directional three-level (TL) rectifiers is built by proposing two equivalent TL arms for topology derivation. A series of TL rectifiers are derived by using double TL and multi TL methods, and their characteristics are compared at the same time. A novel seven-switch double TL rectifier is constructed, and its operational principle and control algorithm are illustrated as well. Lastly, its waveform and harmonic spectrum are compared to those of multi TL rectifiers, and the adopted rectifier gains better performance and unit PF.展开更多
针对现有变压器无法应对高渗透率可再生能源出力强波动性引起的电压骤降/骤升等问题,提出1种基于三桥臂功率变换器的新型混合配电变压器HDT(hybrid distribution transformer)。该方法通过在现有配电变压器的一次侧增加1个串联三桥臂功...针对现有变压器无法应对高渗透率可再生能源出力强波动性引起的电压骤降/骤升等问题,提出1种基于三桥臂功率变换器的新型混合配电变压器HDT(hybrid distribution transformer)。该方法通过在现有配电变压器的一次侧增加1个串联三桥臂功率变换器来实现。所提新型混合配电变压器具有可降低功率变换器额定功率和增加1个额外电流回路以提升变压器自由度的优点。此外,为进一步提升变压器的电能质量,所提方法综合了电压矢量,可补偿电压骤降/骤升和电网电压谐波对变压器的不利影响,提高了电网的功率因数,提升了配电网的输电效率。最后,讨论了所提混合配电变压器的配置和控制策略等,并通过仿真实验分析,验证了所提方法的有效性和优越性。展开更多
文摘An intelligent power factor correction scheme is presented for three phase low power factor loads. This new scheme is able to perform individual phase sensing of parameters by monitoring at all times to sense a change in system parameters and affects individual phase correction by applying the exact amount of reactive components needed for each phase, and can also reduce negative sequence current caused by the load to improve system balance. An optimization criterion is used for the proper calculation of reactive power steps in a power compensation installation of capacitor banks. The criterion is enabled by sampling measurements performed on the electrical plant examined within specific interval of time.
文摘Mathematical modelling for power DC/DC converters is a historical problem accompanying DC/DC conversion technology since 1940’s. The traditional mathematical modelling is not available for complex structure converters since the differential equation order increases very high. We have to search other way to establish mathematical modelling for power DC/DC converters.We have theoretically defined a new concept-Energy Factor （EF） in this paper and researched the relations between EF and the mathematical modelling for power DC/DC converters. EF is a new concept in power DC/DC conversion technology, which thoroughly differs from the traditional concepts such as power factor （PF）, power transfer efficiency （η）, total harmonic distortion （THD） and ripple factor （RF）. EF and the subsequential EFV (and EFVD) can illustrate the system stability, reference response and interference recovery. This investigation is very helpful for system design and DC/DC converters characteristics foreseeing. Two DC/DC converters: Buck converter and Super-Lift Luo-Converter as the samples are analysed in this paper to demonstrate the applications of EF, EFV (and EFVD), PE, SE, VE （and VED）, time constant τ and damping time constant τd.
基金National Nature Science Foundation of China(50277017)
文摘Based on a neutral point diode clamped eight-switch configuration, a general mathematical model of single phase bi-directional three-level (TL) rectifiers is built by proposing two equivalent TL arms for topology derivation. A series of TL rectifiers are derived by using double TL and multi TL methods, and their characteristics are compared at the same time. A novel seven-switch double TL rectifier is constructed, and its operational principle and control algorithm are illustrated as well. Lastly, its waveform and harmonic spectrum are compared to those of multi TL rectifiers, and the adopted rectifier gains better performance and unit PF.
文摘针对现有变压器无法应对高渗透率可再生能源出力强波动性引起的电压骤降/骤升等问题,提出1种基于三桥臂功率变换器的新型混合配电变压器HDT(hybrid distribution transformer)。该方法通过在现有配电变压器的一次侧增加1个串联三桥臂功率变换器来实现。所提新型混合配电变压器具有可降低功率变换器额定功率和增加1个额外电流回路以提升变压器自由度的优点。此外,为进一步提升变压器的电能质量,所提方法综合了电压矢量,可补偿电压骤降/骤升和电网电压谐波对变压器的不利影响,提高了电网的功率因数,提升了配电网的输电效率。最后,讨论了所提混合配电变压器的配置和控制策略等,并通过仿真实验分析,验证了所提方法的有效性和优越性。
