D-STATCOM控制策略分析与研究

发布时间：2018-05-12 22:09

本文选题：D-STATCOM + 无功补偿　；参考：《中国矿业大学》2017年硕士论文

【摘要】：近年来,大量的非线性负载被使用到电网当中,导致了不可忽视的电能质量问题。这些电能质量问题不仅提高了电能传输损耗,而且降低了电网供电的可靠性。因此改善电能质量问题具有重要意义。配电网静止同步补偿器(D-STATCOM)作为改善电能质量的重要设备,可以快速的补偿系统的无功,从而抑制电网的电压波动和闪变,提高系统的稳定性。本文首先介绍了无功补偿基本原理,并对D-STATCOM系统建立了数学模型,从模型中可以看出,D-STATCOM系统是一个非线性、相互耦合的系统。其次,分析了补偿电流的检测方法,在对p-q和p qi-i法研究的基础上,发现其在电网电压不平衡或者发生畸变时,该方法存在不能准确地检测出谐波、正序和负序分量的缺点。本文采用了改进的检测方法,并通过仿真验证了其在不平衡且畸变的电网电压下,仍然可以准确的检测出各个分量。在此基础上,本文采用模型预测控制,并对基于有限开关序列的模型预测控制(FCS-MPC)进行了深入的研究,发现其存在开关频率不固定和用于预测的数学模型可能不精确的缺点,采用了具有固定开关频率的基于干扰在线观测的D-STATCOM模型预测控制策略,并通过仿真验证了其在固定开关频率和提高模型精度的有效性。在此基础上本文进一步的分析了在不平衡电网电压下D-STATCOM的运行特性,发现其会导致直流侧电压产生两倍频波动和过流的可能,并且两倍频的电压波动经过开关函数的调制,会导致交流侧输出电流产生三次谐波。本文采用改进的开关函数来抑制三次谐波,并分析了具有干扰在线观测的D-STATCOM模型预测控制策略防止过流的能力,最后通过仿真验证了其在抑制三次谐波和过流的有效性。最后对实验样机和实验结果进行了介绍,实验样机包括主电路、检测电路、控制电路等,并且对控制系统的软件和硬件进行了设计,硬件设计主要包括DSP和FPGA总线电路的设计、A/D和D/A电路的设计、继电器电路的设计、通信电路的设计等,软件设计主要包括主程序的设计、中断程序的设计、故障保护程序的设计、通信程序的设计等。最后对实验结果进行了分析,验证了模型预测控制策略的有效性。
[Abstract]:In recent years, a large number of nonlinear loads have been used in the power network, leading to the problem of power quality that can not be ignored. These power quality problems not only improve the power transmission loss, but also reduce the reliability of power supply. Therefore, it is of great significance to improve the power quality. As an important equipment to improve the power quality, the static synchronous compensator D-STATCOMC in distribution network can quickly compensate the reactive power of the system, thus restrain the voltage fluctuation and flicker of the power network, and improve the stability of the system. This paper first introduces the basic principle of reactive power compensation, and establishes a mathematical model for D-STATCOM system. From the model, we can see that the D-STATCOM system is a nonlinear and coupling system. Secondly, the detection method of compensation current is analyzed. Based on the study of p-q and p qi-i methods, it is found that the method can not accurately detect harmonic, positive and negative sequence components when the voltage is unbalanced or distorted. In this paper, the improved detection method is adopted, and the simulation results show that it can detect each component accurately under unbalanced and distorted grid voltage. On this basis, the model predictive control (MPC) is adopted in this paper, and the FCS-MPC-based model predictive control based on finite switching sequence is studied in depth. It is found that the switching frequency is not fixed and the mathematical model used for prediction may not be accurate. The D-STATCOM model predictive control strategy with fixed switching frequency based on interference on-line observation is adopted, and its effectiveness in fixed switching frequency and improved model accuracy is verified by simulation. On this basis, the operating characteristics of D-STATCOM under unbalanced grid voltage are further analyzed. It is found that it will lead to the possibility of double frequency fluctuation and overcurrent of DC side voltage, and the voltage fluctuation of double frequency is modulated by switching function. It will cause the third harmonic generation of the AC side output current. In this paper, the improved switching function is used to suppress the third harmonic, and the capability of the predictive control strategy of the D-STATCOM model with interference on-line observation to prevent the overcurrent is analyzed. Finally, the effectiveness of the algorithm in suppressing the third harmonic and the over-current is verified by simulation. Finally, the experimental prototype and experimental results are introduced. The experimental prototype includes main circuit, detection circuit, control circuit and so on. The software and hardware of the control system are designed. The hardware design mainly includes the design of DSP and FPGA bus circuit, the design of A / R D and D / A circuit, the design of relay circuit, the design of communication circuit, etc. The software design mainly includes the design of main program, the design of interrupt program, etc. Fault protection program design, communication program design, etc. Finally, the experimental results are analyzed to verify the effectiveness of the model predictive control strategy.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM761.12

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