【作者】 袁川；

【导师】 杨洪耕；

【作者基本信息】 四川大学 ， 电力系统及其自动化， 2005， 硕士

【摘要】 近5到10年来,随着高新技术尤其是信息技术的飞速发展,基于计算机、微处理器控制的用电设备和电力电子设备在系统中大量投入使用,使电压凹陷上升为电能质量的主要问题之一。电压凹陷问题及其最经济有效的补偿设备动态电压恢复器(DVR)越来越受到国内外学者和专家的关注,成为研究的热门方向。 现在虽然提出了几种凹陷特征量的检测方法,但都存在一些问题,如算法较复杂和实时性较差等。本文在虚拟三相dq变换检测法的基础上,利用构造的思想提出了改进的电压凹陷特征量的检测方法。该方法可进一步提高检测的实时性,对凹陷的开始和结束时刻的定位更准确,并且计算比虚拟三相dq变换检测法简单,通过算例分析验证了其有效性。 目前提出的DVR的补偿方法有缺损电压补偿法、同相补偿法和最小有功功率补偿法。前两种方法对DVR的功率没有控制作用。最小有功功率补偿法虽然使DVR的输出有功功率最小,但却带来了相位跳变、补偿电压过大和使DVR的视在功率最大等问题。本文首先在最小有功功率补偿法的基础上提出了一种改进最小有功功率补偿法,该方法能使DVR输出的有功功率最小,同时计算和控制都比最小有功功率法简单,还能减轻最小有功功率法补偿后负荷端电压相位跳变而对负荷造成的扰动。为了解决最小有功功率法的补偿电压和视在功率过大的问题,本文提出了综合性能较好的DVR的最小视在功率补偿法,该方法可以使DVR运行时的视在功率最小,大大减小DVR的容量,同时视在功率最小还能对有功、无功功率起到限制的作用,使它们都保持较小,它还可以减小DVR的注入电压幅值。文中对采用最小视在功率补偿法时DVR的功率和注入电压等更多还原

【Abstract】 Since recent 5 years to 10 years, with the rapid development of new technology (especially information technology), various sensitive devices such as electronic devices based on computer and micro-processor have been applied in the industry production. Thus voltage sag became one of main problems of power quality. Voltage sag and its most cost-effective compensation device dynamic voltage restorer (DVR) are being paid more and more attention to and turning into the hottest direction of research.Several detection methods of characteristics of voltage sag were proposed. Unfortunately, they have some problems such as complicated algorithm and time-delay. Based on the detection method which uses delayed single-phase signal to construct three-phase signals and calculates the sag characteristics from the formed signal through dq transformation, this paper propose an advanced detection method of sag characteristics. It reduces time delay, and has simpler calculation. The simulation results illustrates its effects.Currently there are pre-sag compensation method, in-phase compensation method and minimum real-power compensation method for DVR. The former two have no control of the power of DVR. Although minimum real-power compensation method minimize real-power of DVR, it brings disadvantages such as phase jump, increase of the injected voltage and apparent-power. Advanced minimum real-powercompensation method of DVR is proposed first to improve the calculation and control of DVR. In addition, the method can mitigate the disturbs caused by phase jump of the compensated voltage of minimum real-power method. In order to overcome the problems of injected voltage and apparentrpower of minimum real-power compensation, a new method named minimum apparent-power compensation is proposed which minimizes apparent-power of DVR, reduces the capacity and injected voltage of DVR. It also limits real and reactive power of DVR to be lower. Detailed theory comparisons of parameters such as injected voltage and power between minimum real-power compensation and minimum apparent-power compensation have been implemented in the paper. Finally circuit simulations of three power factors have been made, the results demonstrate the Tightness of the comparison conclusions. From the results it is also found that minimum apparent-power compensation is decided by condition of voltage sag, it has no business with the loads characteristics. Therefore the control are simple, in other hand it can maintain the compensation continuity, reduce disturbs to loads.In further study, relation between D phasor and positive component of sag voltages has been found. The discovery resolves some problems in former study. It proves that minimum-apparent power compensation and in-phase compensation are same in condition that loads are symmetrical. Thus minimum-apparent power compensation can decrease the injected voltage of DVR. In addition, in-phase compensation has control effects to power of DVR. This paper also proposed that various compensation methods should be studied from voltage components power expression of asymmetrical three phase circuit to make concept clear and analysis simple. After knowing relation of D phasor and positive component of sag voltages, this paper proposes a new detection algorithm of positive and negative of sag voltages which simplifies construction and calculation greatly. In the end, various compensation methods of DVR are studied when loads are asymmetrical.更多还原