This paper proposes a novel SVPWM （space vector pulse width modulation） strategy for the three-level neutral-point-clamped voltage source inverter, based on the particular disposition of all the redundant voltage ve...This paper proposes a novel SVPWM （space vector pulse width modulation） strategy for the three-level neutral-point-clamped voltage source inverter, based on the particular disposition of all the redundant voltage vectors. The new modulation approach shows superior performance for harmonic voltage and balancing control of neutral-point potential compared to the popular eight-stage centered SVPWM. It realizes suppression of inverter neutral-point potential variation by accurately modifying redundant factor of small vectors pairs, only requiring information of DC-link capacitor voltages and three-phase load currents. This is convenient to apply and is compatible of digital computer realization. Feasibility of the proposed control approach is verified by simulation and experimental results.展开更多
The topology of diode neutral-point-clamped(NPC)three-level inverter is prone to neutral-point potential offset.When the sum of three-phase current is zero,the virtual space vector pulse width modulation(VSVPWM)scheme...The topology of diode neutral-point-clamped(NPC)three-level inverter is prone to neutral-point potential offset.When the sum of three-phase current is zero,the virtual space vector pulse width modulation(VSVPWM)scheme does not cause the neutral-point voltage offset,but it lacks the ability to balance the deviation.For this reason,a neutral-point potential control strategy combining virtual space vector modulation and loop width control is proposed.The neutral-point potential is balanced by introducing the distribution factor for the regions with redundant vectors.For other regions,the potential is controlled by selecting a suitable switching sequence.Meanwhile,the effect on the virtual vector modulation is reduced within the loop width by setting an appropriate loop width,thereby improving the balance effect.The simulation results show that the proposed method has a strong ability to control the offset and has excellent potential balance performance under the conditions of balanced load,unbalanced load and asymmetric capacitance parameters.展开更多
The output current harmonic distortion of a three-level inverter is less than the traditional twolevel inverter.The voltage stress of the semiconductor switch is low.A neutral point potential drift control method is p...The output current harmonic distortion of a three-level inverter is less than the traditional twolevel inverter.The voltage stress of the semiconductor switch is low.A neutral point potential drift control method is proposed to solve the problem of the neutral point potential drift of the three-level inverter.The interaction mechanism between the neutral point potential and the space voltage vector is presented.The small vector output by the inverter is found to be the root cause of the midpoint potential drift.It is found that the fluctuation of the midpoint potential could be suppressed by increasing the capacitance value of the inverter bus voltage stabilizing capacitor.Furthermore,it inhibits the fluctuation of the midpoint potential.The experimental results verify the efficiency and precision of the proposed method.展开更多
研究了含静止无功补偿器(Static var compensator,SVC)的多机电力系统的暂态稳定性。首先建立了含SVC的多机电力系统模型,并基于等效负荷概念,构造出含SVC的电力系统的能量函数,验证了能量函数在故障后单调下降的特性。将SVC势能用并网...研究了含静止无功补偿器(Static var compensator,SVC)的多机电力系统的暂态稳定性。首先建立了含SVC的多机电力系统模型,并基于等效负荷概念,构造出含SVC的电力系统的能量函数,验证了能量函数在故障后单调下降的特性。将SVC势能用并网电压和功率表示,克服了SVC模型复杂给构建能量函数带来的困难。采用提出的能量函数,在修改的3机9节点系统和10机39节点系统中验证了迭代势能界面法(Iterative potential energy boundary surface,IPEBS)的有效性。计算结果表明,与时域仿真法相比较,所得故障临界清除时间(Critical clearing time,CCT)的误差较小。展开更多
为了对特高压(UHV)串补装置高电位平台上的一次设备绝缘和二次系统电磁兼容(EMC)进行优化设计,需要对隔离开关操作或旁路间隙击穿引起的瞬态地电位升(PPR)和电磁骚扰进行测量。为此,提出了高电位、强电磁环境下的瞬态地电位升和电磁骚...为了对特高压(UHV)串补装置高电位平台上的一次设备绝缘和二次系统电磁兼容(EMC)进行优化设计,需要对隔离开关操作或旁路间隙击穿引起的瞬态地电位升(PPR)和电磁骚扰进行测量。为此,提出了高电位、强电磁环境下的瞬态地电位升和电磁骚扰测量方法。采用电磁屏蔽、直流供电、光纤通信等技术措施,研制了主要由高电位平台上的测量仪器、地面上的监控系统和通信系统组成的瞬态测量系统,该系统包含3个屏蔽区域。进行了特高压串补装置真型试验平台的隔离开关操作试验,获得了瞬态测量信号的幅域、时域和频域等特征。对瞬态测量系统的功能性测试表明:其屏蔽效能>40 d B,电磁兼容抗扰度满足国标规定的3级及以上且试验评价结果均为A级,工频耐压和冲击耐压分别为4、10 kV,主要性能指标满足特高压串补装置瞬态地电位升和电磁骚扰的测量要求。展开更多
文摘This paper proposes a novel SVPWM （space vector pulse width modulation） strategy for the three-level neutral-point-clamped voltage source inverter, based on the particular disposition of all the redundant voltage vectors. The new modulation approach shows superior performance for harmonic voltage and balancing control of neutral-point potential compared to the popular eight-stage centered SVPWM. It realizes suppression of inverter neutral-point potential variation by accurately modifying redundant factor of small vectors pairs, only requiring information of DC-link capacitor voltages and three-phase load currents. This is convenient to apply and is compatible of digital computer realization. Feasibility of the proposed control approach is verified by simulation and experimental results.
基金National Natural Science Foundation of China(No.61761027)Postgraduate Education Reform Project of Lanzhou Jiaotong University(No.1600120101)
文摘The topology of diode neutral-point-clamped(NPC)three-level inverter is prone to neutral-point potential offset.When the sum of three-phase current is zero,the virtual space vector pulse width modulation(VSVPWM)scheme does not cause the neutral-point voltage offset,but it lacks the ability to balance the deviation.For this reason,a neutral-point potential control strategy combining virtual space vector modulation and loop width control is proposed.The neutral-point potential is balanced by introducing the distribution factor for the regions with redundant vectors.For other regions,the potential is controlled by selecting a suitable switching sequence.Meanwhile,the effect on the virtual vector modulation is reduced within the loop width by setting an appropriate loop width,thereby improving the balance effect.The simulation results show that the proposed method has a strong ability to control the offset and has excellent potential balance performance under the conditions of balanced load,unbalanced load and asymmetric capacitance parameters.
基金the National Natural Science Foundation of China(No.51407007)。
文摘The output current harmonic distortion of a three-level inverter is less than the traditional twolevel inverter.The voltage stress of the semiconductor switch is low.A neutral point potential drift control method is proposed to solve the problem of the neutral point potential drift of the three-level inverter.The interaction mechanism between the neutral point potential and the space voltage vector is presented.The small vector output by the inverter is found to be the root cause of the midpoint potential drift.It is found that the fluctuation of the midpoint potential could be suppressed by increasing the capacitance value of the inverter bus voltage stabilizing capacitor.Furthermore,it inhibits the fluctuation of the midpoint potential.The experimental results verify the efficiency and precision of the proposed method.
文摘研究了含静止无功补偿器(Static var compensator,SVC)的多机电力系统的暂态稳定性。首先建立了含SVC的多机电力系统模型,并基于等效负荷概念,构造出含SVC的电力系统的能量函数,验证了能量函数在故障后单调下降的特性。将SVC势能用并网电压和功率表示,克服了SVC模型复杂给构建能量函数带来的困难。采用提出的能量函数,在修改的3机9节点系统和10机39节点系统中验证了迭代势能界面法(Iterative potential energy boundary surface,IPEBS)的有效性。计算结果表明,与时域仿真法相比较,所得故障临界清除时间(Critical clearing time,CCT)的误差较小。
文摘为了对特高压(UHV)串补装置高电位平台上的一次设备绝缘和二次系统电磁兼容(EMC)进行优化设计,需要对隔离开关操作或旁路间隙击穿引起的瞬态地电位升(PPR)和电磁骚扰进行测量。为此,提出了高电位、强电磁环境下的瞬态地电位升和电磁骚扰测量方法。采用电磁屏蔽、直流供电、光纤通信等技术措施,研制了主要由高电位平台上的测量仪器、地面上的监控系统和通信系统组成的瞬态测量系统,该系统包含3个屏蔽区域。进行了特高压串补装置真型试验平台的隔离开关操作试验,获得了瞬态测量信号的幅域、时域和频域等特征。对瞬态测量系统的功能性测试表明:其屏蔽效能>40 d B,电磁兼容抗扰度满足国标规定的3级及以上且试验评价结果均为A级,工频耐压和冲击耐压分别为4、10 kV,主要性能指标满足特高压串补装置瞬态地电位升和电磁骚扰的测量要求。
