【作者】 刘飞；

【导师】 邹云屏；

【作者基本信息】 华中科技大学 ， 电气工程， 2005， 博士

【摘要】 Q随着电网中非线性负荷的大量增加,由此带来的谐波危害和治理问题日益受到关注。混合有源滤波器(HAPF)利用无源滤波器(PPF)为有源电力滤波器(APF)分压或分流以减小对APF 容量的要求,同时利用APF 控制灵活的特点弥补PPF 补偿性能的缺陷,是当前APF 研究领域的一个重要方向,并且在中高压大容量的谐波治理中有着广阔的应用前景。本文围绕中高压系统谐波治理的问题,主要从以下几方面开展研究并取得了如下成果: (1)全面比较了当前各种混合有源电力滤波器技术方案的优缺点和适用范围,选取了APF 承受基波电压和电流都较小的串联谐振注入式HAPF 方案作为本文的研究重点。通过建立HAPF 系统基于瞬时值的线性微分方程组,进行线性代数坐标变换的方法,分析了HAPF 的单相等效电路与三相电路在暂态和稳态条件下的等价性。(2)本文提出了C 型HAPF 方案,其中的APF 不承受基波电压、电流,且只负担部分谐波电流,直流侧电压与系统电压之比较低,因而容量可进一步减小,有利于工程实现(该方案正在申请中国发明专利,专利申请号:03128234.2)。论文研究了两种用于C 型HAPF 的控制方法:即同时检测网侧电流和负载电流的复合控制方式,以及只需要检测网侧电流的指定消谐控制方式,并分析比较了这两种方式的滤波效果和响应速度。(3)本文针对二阶HAPF 设计了两种复合控制方法:即精确对消特定次数谐波的复合控制方法,和采用两个一阶滞后环节串联来近似二阶积分的复合控制方法。论文采用了通过使APF 发出特定相位的基波电流来实现其直流侧电压的闭环控制策略,并推导了控制系统近似数学模型。本文还设计了一种电压源型逆变器输出电流波形控制方法,即用状态反馈环节保证系统的稳定性,同时依靠重复控制器提高输出电流的跟踪精度。(4)当HAPF 和容性负载并联运行时,论文以二阶HAPF 为例,详细分析了在多种接线方式下发生谐振的可能性,并设计了在可检测电流量受到限制的条件下抑制并联谐振的控制方法,同时指出对于谐波电压源,由于并联型有源电力滤波器的固有缺陷,要想改善幅频特性,需要大幅增加APF 的电流容量。更多还原

【Abstract】 With continuous proliferation of nonlinear loads in grid, the problem of harmonic contamination and treatment attracts more and more attention. Because the hybrid active power filters(HAPF) can utilize the strongpoint of both passive filters(PPF) and active power filters(APF) and offset their weakness, it has been an important area of research and believed to have wider application. The primary purpose of this article is to find a cost-effective and practical solution for harmonic compensation in high-voltage, high-power situation, the studies carried out in the paper and the corresponding results are as follows. (1)This paper reviews the existing HAPF methods applying to high-voltage grid and points out their advantages and disadvantages. Since the APF in the HAPF of LC series resonance injecting type only support a little fundamental voltage and current, the present study therefore focus on this kind of HAPF. By establishing differential equations and processing coordinate conversion, the equivalence between the HAPF single phase equivalent circuit and the three phase system is discussed. (2)The C type HAPF scheme is proposed for the first time, in which the APF doesn’t need to bear fundamental voltage, current and total harmonics. So the APF capacity can be small and its DC voltage level is decreased (The scheme is now applying for a Chinese patent, the applying number is 03128234.2).Two control strategies for the C type HAPF, which are the combined control method and the selective harmonic compensation one, are also explored and analyzed. (3)For the second order HAPF, the paper puts forward two combined control methods: one can compensate some appointed harmonics accurately, the other one can attenuate harmonics higher than 3rd to more than 20dB. The close loop control strategy of the APF’s DC voltage is also presented and the approximate mathematical model is developed with averaging and small signal perturbation method. The state feedback and repetitive control algorithm are adopted to correct the output current waveform of the voltage source inverter in the HAPF. In this control strategy, the state feedback loop is used to guarantee system stability and the repetitive control loop is to improve current waveform quality. (4)When the HAPF is in parallel with the capacitor load, the resonance possibility of some typical connection mode is analyzed in detail by taking the second order HAPF for example. A efficient control algorithm is presented to suppress the resonance caused by load harmonics. Even in some certain circumstance that the available current measuring values are limited, the performance of the algorithm is still good if the disturbance observer is used. However for the grid voltage harmonics, it is shown that the capacity of APF would be unacceptably large to restrain respective resonance. (5)Through theoretically investigating into the convergence process of the two weighting factors in adaptive harmonic filter, two novel algorithms are presented to modify the least mean square(LMS) algorithm. The first one can estimate the steady-state weighting values from their initiative variety, and the second one update the step-size from the time-average of error signal to provide a fast convergence at early stages and ensure a small final maladjustment. Both of them can greatly shorten the transient period while keeping steady-state accuracy.更多还原