| 1. | The negative sequence current of impedance - matching balance transformer
阻抗匹配平衡变压器的负序电流 |
| 2. | The results indicate that asvg not only can compensate reactive currents , but also can effectively filter the harmonic currents , negative sequence currents and zero sequence currents
仿真结果证明基于空间矢量调制的asvg既能够补偿不平衡系统的无功功率，同时又能够有效地滤除系统中的谐波、负序和零序等有害电流。 |
| 3. | Active power filter ( apf ) is an advanced power electronic device ， which can be used for compensating harmonics , reactive power and negative sequence current . compared with conventional compensation devices , active power filter has advantages of real - time and accuracy
有源电力滤波器是一种新型谐波、无功补偿装置，和传统的补偿装置相比，有源电力滤波器具有很大的优势：可以对谐波、无功以及负序电流实现实时、准确的补偿。 |
| 4. | The following is the main works and conclusions of this thesis . the novel upfc needs high power rate because it is generally used in high voltage transmission lines . after studied high - power converters and the literatures of upfc , the main circuit topology of novel upfc base on diode - clamping multilevel inverter is presented and the principle of using novel upfc to eliminate zero sequence and negative sequence currents is analyzed
本文所做的主要工作及得出的主要结论如下：由于upfc一般用于高压输电线，其功率等级要求很高，在综合研究大功率变换器和upfc现有文献的基础上，提出了基于二极管箝位多电平变换器的新型upfc的主电路拓扑，分析了用其来滤出高压输电线非全相运行时所产生的零序和负序电流的原理。 |
| 5. | Unified power flow controller ( upfc ) is one of the most powerful and most promising controllers of facts . if we use upfc to control the transmission parameters , terminal voltage , line impedance and phase angle in normal situation and use it to compensate zero sequence and negative sequence currents when one of transmission lines is cut off , we can implement two phases operating in high voltage transmission lines , which can improve stability and reliability for the transmission system
统一潮流控制器（ upfc ）是功能最强、最具发展潜力的灵活交流输电系统（ facts ）控制器之一，如果在常规条件下，用upfc实现输电线路的电压调节、移相、潮流控制、阻尼振荡等功能，在发生单相永久性接地或单相断路故障时，由传统的三相跳闸改为单相跳闸，用upfc的并补来滤除两端系统的零序和负序电流，用upfc的串补来提高输电线的传输功率，以实现两相长期运行，那么输电系统的稳定性、可靠性将大大提高。 |
| 6. | This paper focuses on the control strategies to improve the performance of the three - phase ac - dc pwm voltage - source - converters ( vsr ) under unbalanced power supply . the problems such as negative sequences current , voltage and current harmonics and un - constant ( un - smooth ) power flow from ac to dc side are discussed in this paper . the analytical solutions for negative sequence current and harmonic current elimination are obtained by fully feed - forward of negative sequence voltage and producing a non - harmonic current command of the inner - loop
电网不平衡时，基于电网平衡为约束条件设计的三相vsr将出现不正常运行状态，比如三相vsr交流电流中出现负序分量，使交流电流严重不对称；直流电压和交流电流中出现非特征谐波分量，使直流电压和交流电流波形发生严重畸变；三相vsr从电网吸收不平衡的瞬时功率等一系列问题。 |
| 7. | As a result , this paper gives a corresponding harmonic prevent me asure . finally , according to the asymmetrical characteristics of electrical traction loads , this paper studies the negative sequence currents under different loads and makes a piece of advice for reducing the negative sequence currents produced
最后，还根据电力牵引负荷三相不对称的特点，分析了阻抗匹配平衡变压器在不同负荷条件下的负序电流，对如何减小电力牵引负荷的负序电流提出了一点建议。 |
| 8. | There is no literature that discusses using upfc to compensate zero sequence and negative sequence currents and conventional upfc is three - phase three - wire , which cannot deal with zero sequence current , so we must improve the conventional upfc in order to add a function of zero sequence and negative sequence currents compensation
传统的upfc为三相三线制结构，不能处理零序电流，因此必须对传统的upfc进行改进，使其既能保持原有的功能，又能增加滤序功能。我们称这种改进后的upfc为新型upfc 。 |
| 9. | On the calculation , we can hold the conclusion that the two kinds of compensators have no distinct difference at the technical aspect under circumstances of two - phased compensation . the effect of decreasing negative sequence current and harmonics ratio is indistinct , however , both are effective in increase power factor
通过仿真发现，这两种补偿方案在技术方面的差别不大：两相补偿模式下，在降低负序和滤波方面，效果都不明显；对提高功率因数的作用显著。 |
| 10. | The validity and superiority of all these are proved by use the parallel converter of novel upfc to implement reactive current compensation , zero sequence and negative sequence currents compensation , harmonic currents compensation and the mixed compensation of them . this thesis also studies that use novel upfc to implement two phases operating in high - voltage transmission lines by theory analyze and simulation testify
提出了基于多电平变换器的广义大功率有害电流补偿的概念，提出了适合于它的多环定时滞环控制方案，通过用新型upfc的并联变换器实现无功补偿、零序和负序补偿、谐波补偿及它们的综合补偿来验证了其有效性和优越性。 |
