【作者】 梁祖权；

【导师】 于继来； 束洪春；

【作者基本信息】 哈尔滨工业大学 ， 电力系统及其自动化， 2008， 博士

【摘要】 统一电能质量调节器(UPQC)是用户电力中一机多用、具有综合电能质量调节能力的设备,它既可以改善电网输入电流的品质,也可以改善负载侧电压的品质,是最能解决多种电能质量问题的有效设备之一。目前,UPQC还未能广泛进入工业应用领域,其相关的检测和控制技术还有待进一步完善和提高。本文针对UPQC信号检测、控制模型和控制方法等方面存在的问题展开深入研究,并提出了新的检测与控制方法。这些工作对于丰富UPQC的检测与控制的基础理论,对于推动UPQC向大规模工业应用,均具有重要意义。UPQC的电压电流信号中除包含正序基波分量外,还可能存在负序和零序基波分量以及其它谐波成分。目前普遍采用基于瞬时无功功率理论的dq0变换方法提取正序基波分量,并由此实施对原始信号中非基波分量的补偿。dq0变换方法计算量较大,硬件实施较复杂,且不适用于单相检测场合。针对此问题,本文在分析三角函数提取基波电压电流成分有关信息的基础上,提出了一种检测UPQC电压电流信号的新方法。该方法利用待检测信号与正弦和余弦参考信号的少量乘除法运算,快速获得待检测信号中的基波电压和基波电流表达式,为高效补偿待检测信号中的非基波分量奠定了基础。同时,该方法能够动态实时跟踪系统频率和正序基波成分幅值与初相位的变化,提高了方法对系统运行工况变化的适应性。某些电力设备,在将其模型由abc坐标系变换到dq坐标系后,仍然存在d、q轴间的交叉耦合,无法实施完全解耦控制。UPQC的dq坐标模型也不例外。针对此问题,本文提出了一种实现完全解耦的新方法:在原模型由abc坐标系变换到dq坐标系的基础上,再增加一次由dq至αβ间的变换,就可使得再变换后的模型,其各轴分量间具有完全解耦的特性。利用此新方法,建立了UPQC的完全解耦模型。完全解耦后的模型,为在一定控制模式和控制方式下实现UPQC的解耦控制或控制系统的解耦设计提供了便利,有助于提高系统控制或系统设计性能。根据UPQC串并联部分在系统控制目标上的不同分工,可以将UPQC的控制模式划分为串压并流模式和串流并压模式,两种模式都可以分别采用开环方式和闭环方式进行控制。本文分别从两种控制模式和两种控制方式入手,提出了相应的控制策略,给出了不同控制策略下给定参考量、检测量等的计算与检测方法。其中,对开环控制,相关参数的计算充分利用了UPQC的解耦模型;对闭环控制,由于控制目标是通过特定的偏差信号进行自动调整,可以不依赖于UPQC串并联部分的具体数学模型,但可以利用解耦模型对闭环控制系统的参数进行设计。仿真与实验结果表明:无论哪种控制模式,按照本文提出的控制策略,都可以实现UPQC的控制目标,且对相同的控制方式,两种控制模式的性能相近。UPQC直流电容电压的控制,常采用PI控制器。PI控制器由于受到设计参数数量的限制,其控制性能可能难以达到比较理想的程度。由于分数阶PIλDμ控制器在传统PID控制器的基础上增加了调节参数的个数,提高了控制器设计与控制规律优化的空间。鉴于此,本文将分数阶PIλDμ控制器引入UPQC直流电容电压的控制,设计的分数阶PIλDμ控制器经仿真分析表明:分数阶PIλDμ控制器与传统PI控制器相比,有助于提高UPQC直流电容电压的动态控制性能。本文研究工作得到了国家自然科学基金项目(项目编号:50467002)的资助。更多还原

【Abstract】 Unified power quality conditioner (UPQC) is a device multi- function and it can settle many power quality problem which is one of the most important equipment among the custom power devices. UPQC can not only improve the current quality of the power network but also enhance the voltage quality of the power load. Now it is not widely used in industrial application and its detecting and control technique need to consummate further. This dissertation is dedicated to investigate its signal detecting, control models and control strategies and give the new detecting and control strategy. These researches are significant to improve the cosmically industrial applications of UPQC.There are negative sequence elements, zero sequence elements and other harmonics ingredients in voltage and current signals. The dq0 transformation method based on the instantaneous reactive power theory is the most popular method to UPQC in compensating the non-fundamental elements of the signal. The calculation of the dq0 method is large, its hardware in utility is complex and it is not suitable to the single-phase UPQC. A novel non-positive fundamental sequence voltage and current detecting method is presented based on analyzing the function of trigonometric function in detecting the fundamental positive sequence voltage and current. It achieved the expression of fundamental positive sequence voltage and fundamental positive sequence current by using a few calculation of pending test signals multiplies with a cosine function and a sine function. The compensation of the non- fundamental positive sequence ingredients is established on this method. Furthermore, this method can follow the change of the frequency and primal phase angle in dynamic and real-time. It increased the adaptability when parameters of system had changed.The double-loop strong coupling problem was existed in the model of some power devices if they were transformed from abc coordinate system to dq coordinate system. So the entirely decoupling control is impracticability. It is the same with the model of UPQC. According to it, a novel decoupling method is proposed in this paper: The model is established by adding a transformation from dq system toαβsystem which has got from abc system to dq system. The elements of each coordinate are decoupled completely in this new model. Using this new method, the entirely decoupling model of UPQC has achieved. The decoupling model of UPQC is advantage to the decoupling control and control system design under some control modes and control manners. It is helpful to enhance the control results and system design.The UPQC control can be sort of series/voltage shunt/current and series/current shunt/voltage mode based on the different control objects of series part and shunt part. Both modes can be controlled by open-loop and close-loop manner. Different control strategies were proposed under two control modes and control manners. Method which calculated the reference value and detecting term was presented under different control strategies. The parameter calculations are taken full advantage of UPQC decoupling model in open-loop control. Otherwise, as the control object is auto-conditioning by given error signals in close-loops, it is independent of UPQC series and shunt model. Yet, it is very important to design the parameters of close-loops. Simulation and experient results show every kind of control mode can realize the control objects of UPQC. The results of two control modes are almost the same when they are under same control manner.The PI controller, which is restricted to its quantity and capability of parameters, is always used in UPQC DC voltage control and the control capability is difficult to achieve perfect. The fractional PIλDμcontroller has more parameters than traditional PID controller and it expands the optimization field of controller design and control rule. It is introduced into the UPQC DC voltage control. The simulation shows that the control results by using PIλDμcontroller are helpful to enhance the dynamic control capability than the traditional PI control. This research work is supported by National Nature Science Foundation of China (50467002).更多还原