【作者】 刘定国；

【导师】 罗安；

【作者基本信息】 湖南大学 ， 电气工程， 2008， 硕士

【摘要】 随着大功率电力电子装置等非线性、时变性负荷在电网中的大规模应用,电网谐波污染和无功缺额越来越严重,与此同时,用户对电能质量要求却越来越高。因而,电压质量和谐波的问题变得越来越突出。研制出输配电谐波治理和大容量无功补偿装备,对无功、谐波实施有效、灵活的控制和补偿,进而改善电压质量、降低谐波含量已势在必行。无源滤波器作为传统的谐波治理手段,由于存在只能滤除特定次谐波和可能与电网发生串并联谐振等缺点,将逐步被新型装置所取代。混合型有源滤波器由于有效综合了有源滤波器和无源滤波器的各自优点,已成为谐波治理和无功补偿一体化系统的主要研究和发展方向。本论文围绕一种谐振注入式混合型有源电力滤波器(ITHAPF)工程应用中的难点,着重讨论了其直流侧电压控制、电流跟踪控制、以及综合设计等方面的问题,并在理论研究的基础上提出了基于ITHAPF的谐波分析与治理一体化系统实现方案,最终实现了ITHAPF的工程应用。ITHAPF中基波谐振支路的存在,决定了其直流侧电压很难通过对逆变器的基波有功电流的控制来维持平衡。一般采用的方法是用不可控整流电路来维持直流侧电压。然而在装置的实际运行当中,当装置接入点电压为非理想电压时,逆变侧的能量倒灌常常会引起直流侧电压的抬高甚至飙升,进而影响到系统的补偿性能,危及系统的安全运行。本文分析了电网电压跌落和电网背景谐波电压导致ITHAPF直流侧电压抬升的原因,在此基础上,提出了采用多重化主电路形式、合理选择注入支路参数、增加直流侧能量泄放回路及直流侧采用PWM可控整流电路等方法来稳定直流侧电压。所提方法为整个装置的高效、稳定、安全运行提供了必要的前提条件。针对ITHAPF的电流控制问题,本文分析了ITHAPF的结构特点,并建立起了对其进行谐波电流控制的模型,在此基础上提出一种基于递推积分的模糊自整定PI控制方法。其中,应用递推积分实现了对周期量的稳态无差控制,提高了控制的精确性;应用模糊算法进行比例和积分系数的在线调整,在确保控制精度的同时大大改善了PI控制算法的动态性能。为了减小系统延时对装置的稳定性及控制精度的影响,本文采用一种带预测补偿的选择性谐波检测方法。文章还对逆变器PWM控制信号的产生方法和逆变器的死区效应的补偿方法进行了介绍。ITHAPF主电路参数对其滤波性能具有较大的影响。本文在理论分析和实践经验的基础上,提出了一套适合于大功率谐波抑制和无功补偿的ITHAPF的结构和参数设计方法:对于单调谐滤波器的设计,在根据治理对象的实际情况确定好调谐次数的基础上,主要从容量、成本和品质因素这三个方面进行考虑;对于注入支路的设计,除了要考虑单调谐滤波器设计的几个因素之外,还应重点考察有源逆变器输出谐波电流注入电网的能力以及基波谐振支路的分压;对于输出滤波器的设计,主要从开关毛刺滤除能力、有效谐波输出能力和谐波的动态跟踪能力三个方面进行考虑;耦合变压器的设计原则是在确定容量之后,应更好地匹配有源部分的电压和电流,以便使功率开关器件的容量得到充分的利用;在逆变器直流侧电容的设计中,其电压取值需在保证滤波器的电流跟踪能力和有效降低成本两者之间折中取值。另外,为了减小逆变器直流侧电容电压的波动,电容必须有一定的容量要求。在此设计方法的基础上,本文提出了基于ITHAPF的谐波分析与治理一体化系统的实现方案,还完成了整个一体化系统软、硬件的调试,并在实地进行了投运,取得了良好的应用效果。更多还原

【Abstract】 Because of large-scale applications of nonlinear and time-varying loads such as high-power power electronic equipments, the harmonic pollution and the lack of reactive power in power grid are getting worse. At the same time, the customers have more and more strict requirement to electric power quality. The problem of voltage quality and harmonic becomes more and more serious. Developing equipment with big capacity for suppressing harmonic and compensating reactive power efficiently and then improving voltage quality and decreasing harmonic content is going necessarily. Passive filter (PF) is a traditional harmonic suppressing device. However, because it can only suppress some specific-order harmonic currents and has the possibility of series parallel resonance with power grid impedance, it will be gradually replaced by new device. The hybride active power filter (HAPF) has the advantages of active power filter (APF) and PF both, so it becomes the main research and development direction of harmonic suppressing and reactive power compensating integrated system.Focusing on some difficulties in the project application of injection type hybrid active power filter (ITHAPF), some factors of ITHAPF were emphatically discussed, such as DC voltage control, current tracking control, and comprehensive design. Base on theoretical research, the realization scheme of harmonic suppressing and reactive power compensating integrated system was presented, and the project application of ITHAPF was carried out.The existence of fundamental series resonance circuit (FSRC) in ITHAPF decides that its DC-voltage can hardly be sustained by controlling the active current of the converter. The common way is using uncontrollable rectifier. However, when Point of Common Coupling (PCC) voltage is not ideal, the energy from AC side will raise the DC-voltage up and then impact the performance and security of the system. This thesis analyzed the reasons of rising of the DC voltage. Based on this, four methods were proposed for solving the DC over-voltage problem including selecting different configurations of APF, optimizing the injection circuit , adding energy releasing circuit and adopting controllable PWM rectifier in DC side. The methods proposed provided precondition for high efficiency, stability and security of whole system. Aiming at the current control of ITHAPF, this thesis analyzed the configuration characteristic of ITHAPF and established its harmonics current control model. Based on this, a new current control algorithm was proposed. Thereinto, recursive integral proportional integral (RIPI) was adopted in this algorithm to eliminate steady error, and precision of controller was improved; fuzzy arithmetic was used to adjust the coefficients of RIPI online for improving the dynamic performance of PI control. A selective harmonic current detection method including time-delay phase angle compensation is proposed for decreasing the influence of system time delay on the stability and control procession of the system. Generation of PWM signal of inverter and compensation of dead-time effect were presented also in this thesis.The main circuit parameters of ITHAPF have a great affect on its performance. Based on theoretical analysis and practical experience, a set of design methods of configuration and parameters for high-power ITHAPF was proposed. In the design of single tuned passive filter, capacity, cost and quality factor should be considered chiefly after tuned frequency was determined according to harmonic current resources. In the design of injection ciruit, the ability of active part harmonic current injection and the voltage which FSRC undertakes should be considered mainly beside the factors proposed in passive filter design. For the design of output filters, suppression of switching harmonic, the abilities of harmonic current output and dynamic tracking should be considered first. The design principle of coupling transformer is that after its capacity was determined, current and voltage of active part should be matched better so as to the capacity of power switching device could be used fully. In the design of DC capacitance, its voltage should have a moderate value considering current tracking ability and cost of active filter. In addition, for diminishing the DC voltage fluctuation, DC capacitance should have adequate capacity. Based on the design principles mentioned above, the realization scheme of an integrated system based on ITHAPF for harmonic current analysis and suppression was proposed in this thesis. Debugging of the integrated system including software and hardware has been finished successfully. The system has been put into use in one substation and application result is very good.更多还原