【作者】 于晶荣；

【导师】 章兢；

【作者基本信息】 湖南大学 ， 控制科学与工程， 2009， 博士

【摘要】 论文对低压配电网有源电力滤波器(Active Power Filter,APF)的参考电流计算方法、控制技术、主电路优化设计等关键技术进行了深入研究。APF能治理谐波污染、补偿无功功率、平衡三相电流,是改善低压配电网电能质量的有效手段。然而低压配电网APF在国内的应用尚未达到成熟阶段,在工业化推广过程中存在很多技术问题有待解决。为此,论文针对低压配电网APF应用过程中的关键技术进行了细致深入的研究,主要内容包括:(1)提出了一种基于复合低通滤波器(Low Pass Filter,LPF)的参考电流计算新方法。研究了基于FBD(S. Fryze,F. Buchholz,M. Depenbrock)法的参考电流计算原理,分析了LPF对参考电流计算结果的影响;设计了基于模糊决策的复合LPF,该复合LPF由截止频率为10Hz和30Hz的双二阶Butterworth LPF组成,模糊决策单元根据负载电流的波动幅度和谐波电流的最低次数进行模糊推理,以确定优先选用的LPF。与传统方法相比,该方法解决了参考电流计算算法的准确性和动态性能之间的矛盾问题,在电网电压不对称、谐波电流频率和幅值动态变化的条件下,能够确保参考电流检测结果的准确性,且动态响应速度快、原理简单。理论分析和仿真结果证明了参考电流计算新方法的正确性和有效性。(2)提出了基于空间矢量脉宽调制(Space Vector Pulse Width Modulation,SVPWM)的APF预测电流控制策略。该策略通过自适应线性神经元(Adaptive Linear Neuron,Adaline)预测下一控制周期的参考电流,并采用模糊算法在线调整Adaline的学习率,有效地补偿了APF的逆变器控制等效延时,然后通过SVPWM方法,使APF的输出电流可以快速、准确地跟踪参考电流预测值。仿真结果证明,与未加参考电流预测算法的控制策略相比,采用基于SVPWM的预测电流控制策略后,APF的谐波抑制效果和动态性能均得到明显改善。(3)研究了低压配电网APF控制策略的稳定性,从电流控制内环和电压控制外环两方面分析了控制策略的稳定性。在电流内环控制稳定性的分析过程中,首先建立基于预测电流控制的APF电流环等效结构,并将电流环分解为参考电流预测和SVPWM环节两个串联的闭环,然后用Lyapunov函数分析参考电流预测算法的稳定性,再利用SVPWM控制的APF闭环传递函数分析SVPWM环节的稳定性,以此证明电流控制内环的稳定性;在电压外环控制稳定性的分析过程中,建立了基于PI控制的电压控制环等效结构,利用劳思判据分析电压控制外环的稳定性。低压配电网APF研制成功后,通过上述方法分析了控制策略的稳定性。(4)提出了低压配电网APF输出滤波器的优化设计方法。对低压配电网APF的主电路结构和参数进行了研究和优化设计,详细分析了输出滤波器的功能和设计原则,并根据输出滤波器的功能将低压配电网APF的输出滤波器设计步骤分解,根据APF的容量和补偿性能设计输出滤波器中的VSI侧串联电感;根据功率开关导致的高次谐波特点,设计滤除高次谐波的高通滤波器和电网侧串联电感,并利用遗传算法对输出滤波器的参数进行优化设计。(5)研制了额定输出电流为120A的低压配电网APF,并成功应用于广西某矿业公司的谐波抑制工程。根据主电路优化方法设计了满足低压配电网谐波抑制要求的APF主电路结构和参数,通过基于复合LPF的参考电流计算方法确定参考电流,并利用预测电流控制实现对参考电流的快速和准确跟踪。实际运行结果表明本文设计的APF谐波抑制效果好、动态响应速度快。根据对APF运行数据的分析,论文进一步分析了影响APF补偿性能的各种因素,并提出了一些可行的改善办法。最后,提出了采用APF与电容柜构成的谐波抑制和无功补偿综合系统,实际工程运行结果表明,该综合系统的谐波抑制和无功补偿效果明显,且成本较低,具有良好的工程推广应用前景。更多还原

【Abstract】 Key technologies such as reference current calculation method, control strategy and optimal design of main circuit for low-voltage distribution network active power filter (APF) are deeply studied in this dissertation. APF can deal with power quality problems, but there are many technical issues to be sloved in process of engineering applications. The research on low-voltage distribution network APF is of great importance to its early industrialization application, and the main research content of this thesis are as follows:(1) A novel reference current calculation method based on composite low pass filters (LPFs) is proposed. S. Fryze, F. Buchholz, M. Depenbrock (FBD) method is studied, and the impact of low pass filter (LPF) on reference current calculation results is analyzed. Composite LPFs are designed, which is composed of two two-order Butterworth LPFs. According to the fluctuation of load current and the lowest frequency of harmonic currents, choice of LPFs is made by fuzzy reasoning. Compared with traditional methods, the contradiction issue between accuracy and dynamic performance for reference current calculation algorithm is resolved with this method. Even under conditions of asymmetry power grid voltage, dynamic changing frequency and amplitude of harmonic currents, this reference current calculation method is of the high accuracy and fast dynamic response, meanwhile it is of simple principle. Correctness and effectiveness of the method is proved by theoretical analysis and simulation results.(2) Predictive current control strategy based on space vector pulse width modulation (SVPWM) is proposed. Adaptive linear neuron (Adaline) is used to predict the reference current for next control cycle, and the learning rate for Adaline is regulated online with fuzzy algorithm.The delay caused by zero-order hold of APF control system is effectively compensated, and the output current of APF can track to predictive reference current fast and exactly with SVPWM mehtod. Simulation results confirmed that, compared with control strategy without reference current predictive algorithm, steady state and dynamic performance of APF with predictive current control strategy is markedly improved.(3) Stability of APF control strategy is analyzed here, which is ayalzed with current control loop and voltage control loop. Predictive current control consists of reference current predictive algorithm and SVPWM method, so its stability depends on the stability of two parts. The equivalent structure of predictive current control is built, then the stability of reference current predictive algorithm is analyzed with Lyapunov function, and stability of APF with SVPWM part is analyzed based on the transfer function of SVPWM loop. As to stability of DC voltage control, equivalent structure of DC voltage control predictive current control is built, and Routh criterion is exployed for stability analysis. With method mentioned above, stability of low-voltage distribution network APF is analyzed after its developement.(4) Optimal design method of output filter for low-voltage distribution network APF is proposed. Structure and parameters of the main circuit for Low-voltage distribution network APF are studied, and detailed analysis of functions and design principles for output filter are developed. Design steps of the output filter are decomposed in accordance with its function, and inductor in the VSI side is designed taking compensation capacity and performance into accounts. While inductor in the power grid side and hign pass filter are designed according to the characteristics of high-order harmonic, and parameters of output filter are optimized with genetic algorithm.(5) Low-voltage distribution network APF of 120A rated current is designed, and it is successfully applicted in harmonic suppression project for some mining companies in Guangxi province. Main circuit of low-voltage distribution network APF is design with ptimization method, which souldly meets the requirements of the harmonic suppression. Reference current is calculated with the method based on composite LPFs, and preditictive control is used to ensure that output cuurent can tracks reference current fast and exactly. Experimental results show that effective harmonic suppression and fast dynamic response are realized by low-voltage distribution network APF by adopting the proposed techniques. However, there are still a small amount of harmonic currents in power grid after compensation by APF. So further analysis of factors which affect compensation performance of APF is taken, and a number of possible improvements are proposed. At last, a comprehensive compensation system for harmonic suppression and reactive power compensation is proposed, which is composed of APF and capacitors, and the practical engineering results confirm that the comprehensive compensation system has obvious effect in harmonic suppression and reactive power compensation. Moreover, it is a cost-effective solution, and the application future is bright.更多还原