单相电路谐波及无功电流新型检测方法

为解决单相电路有源电力滤波器对谐波及无功电流实时检测中存在的不足,根据正交函数的正交特性,提出了一种新的单相电路谐波及无功电流的检测方法,它是利用对畸变电流中的基波有功和无功电流分量分别进行分解,通过加法器、乘法器和积分器计算出谐波和无功电流。电网电压发生畸变时该法可通过增加低通滤波器进行修正,并不影响实时检测的结果。其优点是整个运算电路结构简单、成本低,只需要4个乘法器、2个加(减)法器、1个PLL和2个积分器,且所用元器件可用模拟电路实现,无延时;运算方法简单,省去了复杂的矩阵和反矩阵变换运算;既可单独检测出畸变电流中的任何电流分量,又能得出谐波和无功电流之和。理论分析和仿真实验证实了该方法的有效性和可行性。

New Detecting Method for Harmonics and Reactive Currents in Single-phase Circuits

The most effective measure of suppress harmonic is to use the active electric power filter,(Active Power Filter,APF).Harmonic detecting,an important branch within suppress harmonic,is the foundation in solving other harmonic problems,it is the core technique and the key to APF.Most current Active Power Filters are three-phase,and in fact the damage of harmonic caused by no-line load in single-phase circuit is also very serious.The key technique of single-phase Active Power Filter is also real-time examine of loading harmonics and reactive current,aiming to get instruction signal of competing electric current.In order to meet the demand of detecting harmonic and reactive current of APF in single-phase circuits,a new detecting method for harmonics and reactive current in single-phase circuit is proposed,based on the orthogonality of sine.By respectively decomposing the active and reactive current heft in distorted current,the method computes harmonic and reactive currents through summator,multiplicator and integrator.It can solve the problem of real-time harmonics and reactive detecting of harmonic and reactive current successfully without affecting the real-time detecting result by means of increasing the low pass filter when electrified wire netting's voltage generates abnormal-alteration.The advantages of the detecting method are as the following: the whole operation electric circuit structure is simple,the cost is low;it needs only 4 multiplication machines,2 adders(or subtractors),1 PLL and 2 integrators;and the components used can be realized through emulation electric circuit without delay;the operation method is easy,the complicated matrix and anti-matrix transformation operation is avoided;It can detect not only all the current components in the distorted current,but also the sum of harmonic and reactive currents.Its correctness has been verified by theoretical analysis and simulation.