基于瞬时无功功率理论的三相谐波电流检测研究

发布时间：2018-10-30 06:46

【摘要】：近年来,随着非线性负载设备广泛使用于电力系统中,电网的谐波产生了十分严重的污染。目前抑制电网谐波和无功补偿的主要装置是有源电力滤波器,其关键环节是能够实时准确的检测谐波电流。目前谐波电流检测有许多种方法,其中属赤木泰文提出的“瞬时无功功率理论”应用最为广泛。基于瞬时无功功率理论的三相谐波电流检测方法有p-q法、ip-iq法。其原理是将三相电路电压和电流的瞬时值变换到α-β两相正交的坐标系上进行研究。该方法能在三相电压对称且无畸变的情况下准确检测出基波电流分量,但也存在着自身的局限性。例如在电网电压畸变、三相电路不对称时检测存在误差；不能直接应用于三相四线制电路；无法检测出所需的特征次谐波电流等。针对上述问题,本文进行了一系列的改进措施：无锁相环检测法省去了传统检测方法中的锁相环电路,使检测结果不受电压畸变的影响：利用对称分量法提取基波正序电压,可以有效解决三相电压不对称造成的对基波有功电流检测的影响；通过零序电流分离单元可提取出不对称三相电流中的零序分量,使得谐波检测能够在三相四线制电路中得以应用。此外,一种广义瞬时无功功率理论的发展,突破了原有仅能检测所有谐波电流之和的传统理论,从而使故障中对应的特征次谐波电流检测成为可能。在此基础上,提出了一种基于广义瞬时无功功率理论的任意次谐波电流检测法。该算法在传统ip-iq法的基础之上,适当修改变换矩阵,检测出三相不对称系统中任意次谐波的正、负序分量,然后通过等价三角变换得到各相电流零序分量,三者相加即可得到所需的谐波电流。最后,使用Matlab中的simulink软件进行电路模型仿真和理论分析,并对检测波形进行频谱分析。结果表明,该算法具有很高的准确性和灵活度。
[Abstract]:In recent years, with the wide use of nonlinear load equipment in power system, harmonic generation of power network has caused serious pollution. At present, active power filter is the main device to restrain harmonic and reactive power compensation of power network. The key link of active power filter is to detect harmonic current in real time and accurately. At present, there are many methods for harmonic current detection, among which "instantaneous reactive power theory" proposed by Akimuki Tyrman is the most widely used. The three phase harmonic current detection methods based on instantaneous reactive power theory are p-q method and ip-iq method. The principle is to transform the instantaneous value of voltage and current of three-phase circuit into 伪-尾 two phase orthogonal coordinate system. This method can accurately detect the fundamental current component in the case of three phase voltage symmetry and no distortion, but it also has its own limitations. For example, when the voltage is distorted and the three-phase circuit is asymmetrical, the error can not be detected; it can not be directly applied to three-phase four-wire circuit; the characteristic subharmonic current can not be detected, and so on. In order to solve the above problems, a series of improvement measures are proposed in this paper: the phase-locked loop (PLL) circuit in the traditional detection method is eliminated and the detection results are not affected by the voltage distortion. The fundamental positive sequence voltage is extracted by using the symmetric component method. It can effectively solve the influence of the asymmetry of three-phase voltage on the detection of fundamental active current. The zero sequence component of asymmetrical three-phase current can be extracted by zero-sequence current separation unit, and harmonic detection can be applied in three-phase four-wire circuit. In addition, the development of a generalized instantaneous reactive power theory breaks through the traditional theory, which can only detect the sum of all harmonic currents, thus making it possible to detect the characteristic subharmonic current in fault. On this basis, an arbitrary harmonic current detection method based on generalized instantaneous reactive power theory is proposed. Based on the traditional ip-iq method, the transformation matrix is modified appropriately to detect the positive and negative order components of any order harmonics in a three-phase asymmetrical system, and then the zero sequence components of each phase current are obtained by equivalent trigonometric transformation. The harmonic current required can be obtained by adding the three. Finally, the circuit model simulation and theoretical analysis are carried out by using simulink software in Matlab, and the spectrum analysis of the detection waveform is carried out. The results show that the algorithm has high accuracy and flexibility.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM933.1

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