级联H桥型多电平DVR的控制策略研究
发布时间：2018-12-14 13:32
【摘要】：级联H桥型多电平动态电压恢复器(Dynamic voltage Restorer,DVR)串联在电网和负载之间,可以短时间内消除电压跌落、三相电压不平衡和短暂断电等电能质量问题,是解决电压质量问题公认的最有效措施。然而,级联H桥型多电平DVR在实现补偿功能时直流侧电压存在波动,且当级联数较多时,其数字化实现困难。为此本文以级联H桥型多电平DVR为研究对象,对逆变器与电网功率的流动、级联H桥逆变器的调制策略以及DVR的补偿策略进行了研究。具体内容如下:本文详细的分析了级联H桥型多电平DVR的拓扑结构及原理,建立了DVR的数学模型;在理论上分析了DVR逆变器与电网功率流动的关系,分析表明DVR补偿电压时,逆变单元输出的有功功率和电压幅度与电网电压波动程度、负载功率因数以及DVR输出电压、电网电压、补偿负载电压三者的相位关系等有直接关系。本文通过串联变压器实现DVR与电网的耦合,详细分析了串联在线路中变压器存在励磁涌流的基本原理,给出了抑制变压器励磁涌流的措施。对目前已有的基于瞬时无功功率理论的dq变换法、基于双dq解耦变换的电压检测法以及单相电压跌落检测法进行了总结。详细分析了同相电压补偿策略、完全电压补偿策略以及最小能力补偿策略各补偿策略的优缺点以及适应的应用场合。基于负荷电流相量分析的DVR补偿策略与实际情况不符合、三相不平衡时分析困难、物理意义不清晰的缺点,以负荷电压向量为基础,对负荷电压相量与电压补偿的关系进行了详细的分析,提出了基于负荷电压向量分析的级联H桥多电平DVR补偿策略。概述了载波垂直移相(CLS-SPWM)和载波水平移相(CPS-SPWM)的基本原理,对比分析了CLS-SPWM以及CPS-SPWM调制策略,针对CPS-SPWM调制策略在数字化实现上的困难并结合二重化SPWM调制策略的优势,提出了二重化CPS-SPWM调制策略,给出了二重化CPS-SPWM调制策略的具体调制方式。基于二重化CPS-SPWM调制策略下电平丢失现象,详细分析了调制比与电平数目的关系,得到了级联H桥多电平DVR输出最大电平数时调制比的关系,更进一步,分析得出了调制比下电平数对应的关系。搭建了应用于10k V系统的PACAD/EMTDC10k V仿真模型,对DVR补偿功能、电平数与调制比关系进行了验证,仿真结果验证了理论分析的正确性。
[Abstract]:Cascaded H-bridge multilevel dynamic voltage restorer (Dynamic voltage Restorer,DVR) is in series between power grid and load, which can eliminate power quality problems such as voltage drop, three-phase voltage imbalance and transient power outage in a short time. It is the most effective measure to solve the voltage quality problem. However, the DC side voltage of cascaded H-bridge multilevel DVR is fluctuating when the compensation function is realized, and when the number of cascades is large, it is difficult to realize digitalization. In this paper, the power flow of cascaded H-bridge multilevel DVR, the modulation strategy of cascaded H-bridge inverter and the compensation strategy of DVR are studied. The main contents are as follows: the topology and principle of cascaded H-bridge multilevel DVR are analyzed in detail, and the mathematical model of DVR is established. The relationship between DVR inverter and power flow is analyzed theoretically, and it is shown that when DVR compensates the voltage, the output active power and voltage amplitude of the inverter unit and the voltage fluctuation degree, load power factor and DVR output voltage of the inverter unit are correlated with the voltage fluctuation degree of the power grid, the load power factor and the output voltage of DVR. The phase relationship of grid voltage and compensating load voltage is directly related. In this paper, the coupling of DVR and power network is realized by series transformer. The basic principle of the inrush current of transformer in series is analyzed in detail, and the measures to restrain the inrush current of transformer are given. The existing dq transform method based on instantaneous reactive power theory, voltage detection method based on double dq decoupling transform and single-phase voltage drop detection method are summarized. In this paper, the advantages and disadvantages of the compensation strategies of in-phase voltage compensation, complete voltage compensation and minimum capacity compensation are analyzed in detail. The DVR compensation strategy based on load current phasor analysis is not in accordance with the actual situation, and it is difficult to analyze when the three-phase unbalance and the physical meaning is not clear. It is based on the load voltage vector. The relationship between load voltage phasor and voltage compensation is analyzed in detail. A cascade H bridge multilevel DVR compensation strategy based on load voltage vector analysis is proposed. The basic principles of carrier vertical phase shift (CLS-SPWM) and carrier horizontal phase shift (CPS-SPWM) are summarized, and the modulation strategies of CLS-SPWM and CPS-SPWM are compared and analyzed. In view of the difficulty of digital implementation of CPS-SPWM modulation strategy and the advantages of dual SPWM modulation strategy, the dual CPS-SPWM modulation strategy is proposed, and the specific modulation mode of double CPS-SPWM modulation strategy is given. Based on the phenomenon of level loss under dual CPS-SPWM modulation strategy, the relationship between modulation ratio and the number of levels is analyzed in detail, and the relation of modulation ratio when the output maximum level number of cascaded H-bridge multilevel DVR is obtained. The relation of the level number at the modulation ratio is obtained. The simulation model of PACAD/EMTDC10k V applied to 10kV system is built. The function of DVR compensation, the relation between the level number and modulation ratio are verified. The simulation results verify the correctness of the theoretical analysis.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM761.12
[Abstract]:Cascaded H-bridge multilevel dynamic voltage restorer (Dynamic voltage Restorer,DVR) is in series between power grid and load, which can eliminate power quality problems such as voltage drop, three-phase voltage imbalance and transient power outage in a short time. It is the most effective measure to solve the voltage quality problem. However, the DC side voltage of cascaded H-bridge multilevel DVR is fluctuating when the compensation function is realized, and when the number of cascades is large, it is difficult to realize digitalization. In this paper, the power flow of cascaded H-bridge multilevel DVR, the modulation strategy of cascaded H-bridge inverter and the compensation strategy of DVR are studied. The main contents are as follows: the topology and principle of cascaded H-bridge multilevel DVR are analyzed in detail, and the mathematical model of DVR is established. The relationship between DVR inverter and power flow is analyzed theoretically, and it is shown that when DVR compensates the voltage, the output active power and voltage amplitude of the inverter unit and the voltage fluctuation degree, load power factor and DVR output voltage of the inverter unit are correlated with the voltage fluctuation degree of the power grid, the load power factor and the output voltage of DVR. The phase relationship of grid voltage and compensating load voltage is directly related. In this paper, the coupling of DVR and power network is realized by series transformer. The basic principle of the inrush current of transformer in series is analyzed in detail, and the measures to restrain the inrush current of transformer are given. The existing dq transform method based on instantaneous reactive power theory, voltage detection method based on double dq decoupling transform and single-phase voltage drop detection method are summarized. In this paper, the advantages and disadvantages of the compensation strategies of in-phase voltage compensation, complete voltage compensation and minimum capacity compensation are analyzed in detail. The DVR compensation strategy based on load current phasor analysis is not in accordance with the actual situation, and it is difficult to analyze when the three-phase unbalance and the physical meaning is not clear. It is based on the load voltage vector. The relationship between load voltage phasor and voltage compensation is analyzed in detail. A cascade H bridge multilevel DVR compensation strategy based on load voltage vector analysis is proposed. The basic principles of carrier vertical phase shift (CLS-SPWM) and carrier horizontal phase shift (CPS-SPWM) are summarized, and the modulation strategies of CLS-SPWM and CPS-SPWM are compared and analyzed. In view of the difficulty of digital implementation of CPS-SPWM modulation strategy and the advantages of dual SPWM modulation strategy, the dual CPS-SPWM modulation strategy is proposed, and the specific modulation mode of double CPS-SPWM modulation strategy is given. Based on the phenomenon of level loss under dual CPS-SPWM modulation strategy, the relationship between modulation ratio and the number of levels is analyzed in detail, and the relation of modulation ratio when the output maximum level number of cascaded H-bridge multilevel DVR is obtained. The relation of the level number at the modulation ratio is obtained. The simulation model of PACAD/EMTDC10k V applied to 10kV system is built. The function of DVR compensation, the relation between the level number and modulation ratio are verified. The simulation results verify the correctness of the theoretical analysis.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM761.12
【参考文献】
相关期刊论文 前10条
1 熊飞;吴俊勇;郝亮亮;田明杰;张巨瑞;张皎;;不对称电压跌落下逆变电源的多目标控制策略[J];电工技术学报;2017年01期
2 涂春鸣;吴连贵;姜飞;郭祺;杨洁;熊卓;魏隆;;基于输出最大电平数的级联H桥型动态电压恢复器控制策略[J];电网技术;2017年03期
3 刘子维;涂春鸣;姜飞;杨健;魏钊;;线间多功能DVR的工作机理及仿真分析[J];电力系统保护与控制;2016年21期
4 黄永红;施慧;徐俊俊;张云帅;;改进dq变换的动态电压恢复器检测新方法[J];电力系统及其自动化学报;2016年10期
5 尹尧杰;廖明夫;吕品;刘展翅;王四季;;电压跌落对风力机叶片振动影响分析[J];振动与冲击;2016年10期
6 吴连贵;涂春鸣;姜飞;郭祺;刘子维;;级联H桥型逆变器载波移相正弦脉宽调制输出性能分析[J];电网技术;2016年07期
7 石荣亮;张兴;刘芳;徐海珍;胡超;余勇;倪华;;不平衡与非线性混合负载下的虚拟同步发电机控制策略[J];中国电机工程学报;2016年22期
8 张新闻;同向前;;电容耦合型动态电压恢复器参数建模与控制[J];电工技术学报;2016年06期
9 钟庆;汪逍e，
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