摘 要:随着电力技术的发展，非线性的半导体元件和含有电弧的非线性设备在电力系统中得到广泛的应用，它迫使电能质量下降，给电力系统和各类用电设备带来严重的威胁。所以这里我们要对谐波抑制的方法进行研究，这对提高电能质量，维护电力系统的经济、安全运行意义重大。
本文主要对小波变换和瞬时无功功率理论两种谐波抑制的方法进行了分析和仿真。首先，对基于瞬时无功功率理论的两种经典方法即p-q检测法、ip-iq检测法进行了分析、比较，两种方法都具有较好的精确性，但实时性都不好；然而在电网电压发生畸变时，ip-iq检测法依然能够保证其精确性，但p-q检测法就存在误差了。原来的ip-iq检测法由于低通滤波器在保证了实时性的基础上，不可能完全将谐波滤除掉，对仿真结果总会产生影响，本文提出了以ip-iq检测法改进的方法，以一个计算ip-iq直流分量的模块代替低通滤波器(LPF)得到ip、iq的直流分量，就可以比较精确的计算出直流分量了，从而得到较好的有功电流分量瞬时值。但是改进的算法实时性仍然不够好，在实时性要求较高的场合，这几种方法都不适用，所以本文又对小波分析理论进行分析和仿真，将小波变换应用到谐波检测中，结果表明该方法在精确性和实时性上都显示出很好的优越性，很好地解决了上述几种方法实时性不好的缺陷。
关键词：电力系统 谐波 瞬时无功功率 小波变换
ABSTRACT:With development of the power of technology, nonlinear semiconductor components and non-linear devices containing arc in the power system has been widely used. It forces the power quality decline, and Endanger all kinds of electrical equipment and power systems.So we want to study harmonic suppression method, which can improve power quality, is significant to maintain power system economic, safe of operation.
This paper focuses on wavelet transform and instantaneous reactive power theory two kinds of harmonic suppression methods for analysis and simulation. First, based on instantaneous reactive power theory two classic methods that is p-q assay, ip-iq detection method were analyzed and compared, Both methods have a better accuracy, but timeliness is not good. However, when the grid voltage distorted, ip-iq detection method is still able to ensure its accuracy, but there is error with pq detection method. original Ip-iq detection due to the low-pass filter to ensure the real-time, it is impossible to completely filter out harmonics, that will always have an impact on simulation results, This paper proposed a method to improve ip-iq detection, approach to a calculating modules of ip-iq the DC component instead of a low-pass filter (LPF) to obtain ip, iq the DC component, it can be more accurately calculate the DC component a, thereby obtaining a better instantaneous of active current component. However, the improved algorithm timeliness is still not good enough, in the occasion which required real-time for strict, these methods do not apply, Therefore, this paper has analyzed and simulated the wavelet analysis theory, the wavelet transform is applied to harmonic detection, The results show that the method on the accuracy and timeliness have shown the good superiority, And solves the defects of aforementioned methods which is bad real.
Keywords: Power Systems；harmonic；Instantaneous reactive power；wavelet transform
