电网故障下并网逆变器的控制算法研究

发布时间：2018-07-02 19:51

本文选题：电网不平衡 + 电网电压跌落　；参考：《电子科技大学》2014年硕士论文

【摘要】：随着大功率开关器件和数字信号处理器技术的进步,分布式发电系统得到广泛应用与发展,弥补了传统发电能源的不足。实际电网不是理想的,是个动态复杂的系统,分布式发电系统在电网故障下要保持正常并网工作又要保证电能质量,因此要求逆变器在电网不平衡故障情况下保证注入电网电能质量,在电网电压跌落故障下不脱网,并抑制瞬间大电流冲击,保护设备器件不受损坏。本文对电网故障下逆变器并网控制策略进行了深入的研究。(1)电网故障下的电压矢量的研究和分析。研究分析电网电压不平衡故障时电压正序、负序、零序分量的提取算法,为第三章单同步坐标系控制结构的改进提供依据;研究电网电压跌落故障时电压的分类及派生,为第四章低电压穿越控制算法奠定基础,简化了控制策略的分析。(2)对电网不平衡故障下的并网逆变器控制策略进行分析。首先在电网电压理想条件下对并网逆变器进行建模分析,引出电网电压不平衡条件下对逆变器传统单同步坐标系控制结构的影响,得出传统的单同步坐标系PI控制器结构无法同时跟踪正序分量和负序分量,必然会有二倍基波频率振荡的结论;然后以此结论为依据,提出适应电网不平衡故障的控制结构—双同步坐标系PI控制结构,可以消除二倍基波频率振荡的影响;最后根据控制目标和用户需求的不同,提出不同的控制策略,满足注入电网电流平衡或功率平衡的需求,仿真证实理论分析的有效性。(3)对电网电压跌落故障下并网逆变器的低电压穿越控制算法进行研究分析。针对电网电压跌落故障时并网逆变器的控制难点分别进行研究分析并提出控制策略解决。通过双同步坐标系解耦锁相环得到dv?的瞬时值来检测电网电压状态及跌落深度;并对电网电压跌落期间注入电网功率进行合理分配与控制,防止过流;提出瞬时前馈控制策略抑制电网电压跌落瞬间的大电流冲击,通过理论分析电流冲击的必然性和瞬时前馈控制的有效性,通过仿真实验证实低电压穿越控制算法的有效性,在德阳某公司逆变器调试区50kW储能逆变器设备上进行低电压穿越实验,通过项目认证和验收,并完成零电压穿越实验。
[Abstract]:With the development of high power switchgear and digital signal processor (DSP), distributed power generation system has been widely used and developed, which makes up for the shortage of traditional generation energy. The actual power grid is not ideal, it is a dynamic and complex system, distributed generation system should keep normal grid connection and ensure power quality. Therefore, the inverter is required to ensure the quality of power injected into the power network under the condition of unbalanced fault of the power network, not to get rid of the grid in the case of voltage drop fault, to suppress the instantaneous high current shock, and to protect the device from damage. In this paper, the inverter grid-connected control strategy under power network fault is deeply studied. (1) the research and analysis of voltage vector in power network fault. In order to improve the control structure of single synchronous coordinate system in chapter 3, the extraction algorithm of voltage positive sequence, negative sequence and zero sequence component in unbalanced voltage fault of power network is studied, and the classification and derivation of voltage in voltage sag fault are studied. It lays a foundation for the control algorithm of low voltage traversing in chapter 4 and simplifies the analysis of control strategy. (2) the control strategy of grid-connected inverter under unbalanced power network fault is analyzed. Firstly, the modeling and analysis of grid-connected inverter under ideal grid voltage conditions are carried out, and the influence of grid voltage imbalance on the traditional single-synchronous coordinate system control structure of inverter is introduced. It is concluded that the traditional Pi controller structure of single synchronous coordinate system can not track the positive and negative sequence components simultaneously, and there is bound to be a double fundamental frequency oscillation, which is based on the conclusion that the Pi controller structure can not track the positive and negative sequence components at the same time. The double synchronous coordinate system Pi control structure, which adapts to the unbalanced fault of power network, is proposed, which can eliminate the influence of the frequency oscillation of double fundamental wave. Finally, according to the difference of control objectives and users' demands, different control strategies are proposed. The simulation results show that the theoretical analysis is effective. (3) the low voltage traversal control algorithm of grid-connected inverter under voltage sag fault is studied and analyzed. The control difficulties of grid-connected inverter during voltage drop fault are studied and analyzed, and the control strategy is proposed. By decoupling phase locked loop in double synchronous coordinate system, the DVD? To detect the voltage state and the drop depth of the power grid, to distribute and control the power injected into the power network during the voltage drop, to prevent the overcurrent, and to put forward the instantaneous feedforward control strategy to restrain the large current shock at the moment of the voltage drop. Through the theoretical analysis of the inevitability of current shock and the effectiveness of instantaneous feedforward control, the effectiveness of the low voltage traversing control algorithm is verified by simulation experiments. The low voltage traversing experiment was carried out on 50kW energy storage inverter equipment of a company in Deyang, and the zero voltage traversing experiment was completed through project certification and acceptance.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

【参考文献】