【作者】 李彦林；

【导师】 王明彦；

【作者基本信息】 哈尔滨工业大学 ， 电力电子与电力传动， 2014， 博士

【摘要】 为有效解决分布式电源的接入给电网带来的影响，微电网概念被提出。为保证微电网高效可靠运行，满足客户对高质量电能的需求，微电网电能质量控制技术成为微电网的关键技术之一。与配电网不同，由于微电网中多数微电源接口采用电力电子变流器，使得采用适当的控制策略实现微电网电能质量主动控制成为可能，在微电网中主要通过实现微电源接口微网变流器的复合控制，以及采用相应的控制策略提高微网变流器运行性能来实现电能质量主动控制。本文以微电网为研究对象，对微电网的电能质量主动控制，包括实现储能电源接口变流器复合电能质量补偿功能的多目标控制策略、储能电源接口双四桥臂变流器电能质量控制策略、非理想电压条件下提高微网变流器运行性能的控制策略等问题展开研究。论文首先针对微电网的网络构造、运行特点以及负荷特性，分析微电网结构及其控制方法，指出由于储能微网变流器与电能质量治理装置有相同的拓扑结构，因此具备电能质量主动控制条件；然后分析比较现有三种微电网PQ控制策略，指出由于受到滤波电感误差或电网感抗的影响导致系统性能降低，为改善性能采用功率、电流完全解耦的微网变流器PQ控制策略；最后建立了基于PQ控制微网变流器诺顿等效电路的微电网等效模型，以此为基础深入分析微电网电压波动原因和微电网与配电网间谐波谐振交互机理。为有效抑制电压不平衡、谐波畸变干扰，采用基于自适应陷波器(Adaptive Notch Filter, ANF)的正负序分量分解方法提取电网电压基波正、负序分量，从而实现补偿电流检测和参考电流计算。为充分利用储能电源接口变流器冗余容量，实现电能质量主动补偿，研究具有微电网电能质量主动治理功能的储能微网变流器多目标控制策略。该控制策略可以使储能系统平抑微电网功率波动，同时在全补偿控制方式下实现谐波、无功和不平衡电流的全频段范围补偿，在分频选择补偿控制方式下基于比例矢量比例积分(Proportional Vector Proportional-integral, PVPI)控制还可实现对谐波、无功和不平衡电流有选择的分频进行补偿。两种多目标控制策略可以有效利用储能系统，提高微电网电能质量，减小对配电网的影响。在储能微网变流器多目标控制的基础上，为进一步解决配电网与微电网之间电能质量交互影响，对具有灵活接入方式的超级电容(Super Capacitor, SC)储能电源双四桥臂变流器(Microgrid Power Quality Controller, MGPQC)的控制策略进行研究。在串-并联接入方式下，为补偿公共连接点(Point of Common Coupling, PCC)电压跌落，根据SC的剩余容量(SC-SOC)，提出一种电压跌落协调补偿策略，通过微电源、SC和普通负荷切除之间的协调控制使得PCC电压始终维持在正常水平；在串联接入方式下，分析了电网电压不平衡、谐波畸变对MGPQC传输功率的影响，采用SC储能平抑MGPQC中间直流侧功率波动，提高微电网电能质量，避免配电网对微电网的影响。为实现变流器正、负序电流统一控制，采用多谐振PVPI控制器实现电流内环控制。上述方法提高了微电网电能质量，增强了微电网并网运行能力。为提高电网电压不平衡、谐波畸变条件下LCL滤波微网变流器的运行性能，结合电容电流反馈有源阻尼和电网电压前馈控制，提出基于PVPI控制的非理想电压条件下微电网变流器PQ控制策略，控制策略不需要锁相环和对电流进行正负序分离，计算量小，简化了系统控制结构，并可以改善微网变流器输出电能质量，提高非理想电压条件下微网变流器运行性能；针对电流闭环系统由于结构复杂、参数较多导致的系统参数设计困难，以及通过参数设计提高系统鲁棒性的设计要求，提出一种提高系统鲁棒性的简化电流闭环参数设计方法，采用频率法分析电容电流反馈系数和PVPI控制器各参数对电流环性能的影响，根据稳定性、幅值裕度和相位裕度要求，分别设计电容电流反馈系数、PVPI控制器的相对谐振增益系数和比例系数。该方法采用解析计算，简化了参数设计，提高了系统的稳定性、鲁棒性和动态响应性能。更多还原

【Abstract】 Microgrid is proposed to solve the problems caused by distributed generation on grid effectively. In order to ensure the efficient and reliable operation of microgrid and meet the higher power quality of the customer demand, power quality control becomes one of the key techniques in microgrid research. As a result of the widely use of power electronic-interfaced microsources, microgrid is quite different from distribution grid. By adopting proper control strategy, power quality active control becomes possible, so microgrid can realize the active control on power quality mainly by composite power quality control and improving the operation performance of microgrid converter. This thesis takes microgrid as the research object to conduct research on power quality active control strategies, including multi-objective control strategy of energy storage interface converter for power quality compensation, microgrid power quality control strategy based on energy storage interface double four-leg converter, and control strategy of microgrid converter for better performance under non-ideal grid voltage conditions.Firstly, for the topology, operating characteristics and load characteristics, the structure and control strategy of microgrid are analyzed. The analysis indicates that energy storage microgrid converter has the same topological structure as power quality management equipment, so it can also be used in power quality active control. Secondly, by analyzing and comparing the three microgrid PQ control strategies, the existing problems are pointed out. The analysis indicates that inductance parameter error and grid impedance cause reduction of system performance. In order to improve performance, the thesis proposes a novel microgrid PQ control strategy to realize decoupled control of the power and current separately. Finally, the norton equivalent circuit of the microgrid converter using the PQ control strategy is established. Based on the norton equivalent circuit, a equivalent model of microgrid is established to analyse the reasons of voltage fluctuation and the harmonic resonance mechanism in detail.In order to realize compensative current detection and reference current calculation, the decomposition method of positive and negative sequence components based on adaptive notch filter(ANF) is used to extract the fundamental positive and negative components of grid voltage, which can effectively restrain the voltage unbalance and harmonic interference. To improve energy storage utilization efficiency and achieve active compensative function of power quality, the multi-objective control strategy of microgrid energy storage converter with active power quality management functions is researched. With the proposed control strategy, the energy storage system can not only smooth the power fluctuations, but also compensate current harmonics, reactive power and current unbalance under the control mode of all compensation, and selectively compensate current harmonics, reactive power and current unbalance under the control mode of selective frequency-division compensation based on proportional vector PI (PVPI) control. Adopting the proposed two control strategies, the utilized rate of energy storage system can be enhanced effectively, resulting in the improvement of microgrid power quality and the suppression of its impact on distribution grid.Furthermore, based on research results of the multi-objective control for microgrid energy storage converter, the control strategies of super capacitor(SC) energy storage double four-leg converter(Microgrid Power Quality Controller, MGPQC) are studied to solve interactive influence of the power quality between distribution grid and microgrid. In order to compensate grid voltage sags at the point of common coupling(PCC), a coordinated control strategy based on SC-SOC is proposed to when MGPQC working in series-parallel mode. The proposed control strategy keeps the normal level of grid voltage at the PCC through coordinated microsources, SC and load shedding. In series mode, the influences of voltage unbalance and distortion on the power transmission characteristic of MGPQC is analyzed. In order to improve microgrid power quality and avoid the influence of distribution grid on microgrid, a control scheme using SC energy storage to supress the DC-link power fluctuation is proposed. In the current inner loop, a multi-resonant proportional resonant PVPI controller is adopted to realize the unified positive-and negative-sequence current control. Based on the above methods, power quality of microgrid is improved, and the operation ability connected with grid is elevated effectively.In order to enhance the operation performance of microgrid converter using LCL filter under the unbalanced and harmonic distorted grid conditions, combined with the capacitor-current-feedback active damping and grid-voltage-feedforward control, a microgrid converter PQ control strategy is proposed based on PVPI controller. With the proposed control strategies, neither phase-locked loop nor extraction of positive/negative sequence current feedback signal is needed, simplifying the control structure, improving the power quality of output current and enhancing the operation performance of microgrid converter under non-ideal voltage situations. The system is of high order, many parameters and complicated. Besides, the proper parameter design method should be used to meet the design requirements that enhance the robustness of system. Therefore considering these factors, a simplified parameters design method which can realize better robustness is proposed. The effects of the capacitor-current-feedback coefficient and the parameters of PVPI controller on the current-loop performance are investigated with frequency characteristics analysis, i.e. the stability, phase and amplitude margins. According to the requests of the stability, phase and amplitude margins, the capacitor-current-feedback coefficient, the relative resonant gain factor and the proportional factors could be designed separately. The proposed method simplifies the parameters design procedure using analytic calculation and further improves stability, highly robustness, fast transient response performance of the microgrid converter.更多还原