并网光伏发电故障穿越稳定性研究

发布时间：2018-08-18 13:25

【摘要】：随着光伏发电在电力系统的渗透率不断增加，保证电网安全稳定运行，建立电网友好型的光伏电站是目前光伏行业可持续发展的重要课题之一。电网友好型要求并网光伏系统不仅能在电网正常运行时保证输出电能质量，而且在电网故障时保证不脱网不损坏逆变器，同时充分利用光伏逆变器的快速无功输出能力参与电网的有功和无功调节，实现故障穿越并提供故障期间无功支持。本文首先分析了光伏并网系统在电网故障时，特别是三相不对称故障时的稳定性，包括直流母线电压稳定性，输出有功无功功率稳定性以及谐波稳定性。其次，，本文提出三相以及单相光伏并网逆变器低电压穿越控制系统。重点是针对两级式三相光伏发电系统在电网不对称情况下的表现,后级全桥逆变器的并网电流控制以消除有功功率振荡分量为目标,并将其与前级DC-DC变换电路控制配合,实现电网不对称故障下的低电压穿越。并提出不同的电流环参考电流生成算法。一是基于双同步旋转坐标系的改进控制算法，二是基于并网三相电流与功率矢量关系的直接生成算法。接着，本文完成10kW三相并网光伏系统的直流母线电容选型以及交流侧电感设计，利用MATLAB/Simulink搭建仿真系统，完成不同故障类型，不同跌落深度下光伏并网故障穿越控制策略的仿真验证。最后，依托新能源电力系统国家重点实验室的实验平台，完成对本文所提控制系统的10kW单晶光伏并网逆变系统故障穿越实验验证。
[Abstract]:With the increasing permeability of photovoltaic generation in the power system, to ensure the safe and stable operation of the grid, the establishment of a grid-friendly photovoltaic power plant is one of the most important issues for the sustainable development of photovoltaic industry. The grid-friendly photovoltaic system can not only guarantee the output power quality in the normal operation of the power grid, but also ensure that the inverter will not be removed from the grid when the power network fails. At the same time, the fast reactive power output ability of photovoltaic inverter is fully utilized to participate in the active and reactive power regulation of the power network, to realize the fault traversing and to provide reactive power support during the fault period. In this paper, the stability of photovoltaic grid-connected system, especially the three-phase asymmetrical fault, including the stability of DC bus voltage, the stability of output active and reactive power, and the stability of harmonics are analyzed. Secondly, three-phase and single-phase photovoltaic grid-connected inverter low voltage traversing control system is proposed in this paper. Focusing on the performance of two-stage three-phase photovoltaic power generation system under the condition of grid asymmetry, the grid-connected current control of the full-bridge inverter is aimed at eliminating the active power oscillation component, and it is combined with the control of the former stage DC-DC converter circuit. The low voltage traversing is realized under the asymmetrical fault of the power network. Different current loop reference current generation algorithms are proposed. One is an improved control algorithm based on double synchronous rotating coordinate system, the other is a direct generation algorithm based on the relationship between three-phase current and power vector. Then, this paper completes the DC busbar capacitance selection and AC side inductance design of 10kW three-phase grid-connected photovoltaic system, and uses MATLAB/Simulink to build simulation system to complete different fault types. Simulation verification of the control strategy of photovoltaic grid-connected fault crossing under different drop depth. Finally, based on the experimental platform of the State key Laboratory of New Energy Power system, the 10kW single-crystal photovoltaic grid-connected inverter system of the proposed control system is verified.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM615

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