摘要
近年来,各种非线性和时变性的电力电子装置应用于农村低压电网中,造成低压电网谐波严重污染。为了解决低压电网单相电路电能质量问题中谐波检测算法的问题,对低压电网单相电路电流进行分解,提出一种无锁相环的谐波电流检测算法。该检测算法首先用与低压电网单相电压同相位的单位正余弦电压信号分别与单相电流相乘,然后利用低通滤波器得到单相电流的瞬时基波电流,进而再获得瞬时谐波电流。数学论证表明:当单相电路只需要检测谐波电流时,可以略去检测电路中的锁相环,既能避免畸变电压对检测电路的影响,又能简化算法,提高响应时间。仿真实验表明:在实时性方面,新谐波检测算法能在一个半周期,即0.03 s的时间内跟踪上低压电网电流的基波信号,且当低压电网畸变电流发生突变时,仍能在一个周期(0.02 s)内跟踪上畸变信号,几乎不受波形突变的影响;在准确性方面,没检测之前的畸变电流的谐波含量为41.15%,经过新谐波检测算法后得到的基波中谐波含量仅为1.91%,滤除了95.36%的谐波分量,很好地达到了分离出谐波分量的目的。
In recent years, various nonlinear and time-varying electronic devices were used in low-voltage power grid in rural areas, causing increasingly serious harmonic pollution. In order to simplify the detection of harmonics in single-phase circuit in low-voltage grid, the current in single-phase circuit is decomposed and a new method for such a purpose is proposed without using the phase lock loop （PLL）. The principle of the new detection algorithm is： Firstly, the single -phase current is multiplied by unit sinusoidal and cosinoidal voltage signals with the same frequency of that of circuit voltage respectively and then sent to two low pass filters. Secondly, the outputs of these two low pass filters are again multiplied by the unit sinusoidal and cosinoidal signals to get the active currents. Lastly, by subtracting the active current thus obtained from the original current, the harmonic current can be detected. The function of PLL in this method is analyzed in detail. Mathematical arguments show that, when only harmonic current require to be detected, the PLL can be omitted to simplify algorithms. It can not only avoid the distortion voltage influence on detection circuit, but can improve the response time. Simulation results show that, in the aspect of real-time, the new harmonic detection algorithm can track the fundamental signal of low-voltage grid distorted current in a half cycle （0.03 s）, and when the grid current has a mutation, it still can track the signal in a cycle （0.02s）, hardly affected by the mutated waveform. In terms of accuracy, the harmonic content of the distorted current before detection is 41.15%, after the new harmonic detection, this part down to 1.91%, 95.36% harmonic is filtered. The purpose of separating harmonic component reached. The new harmonic detection algorithm proposed in this paper can accurately detect the harmonic current of single-phase circuit current in low-voltage grid in rural areas, but also in real-time to meet the requirements of urban industrial applicat
出处
《农业科技与装备》
2014年第9期35-38,共4页
Agricultural Science & Technology and Equipment
关键词
农村低压电网
单相电路
谐波检测
无锁相环
仿真分析
low-voltage in rural areas
single-phase circuit
harmonic detection
without PLL
simulation analysis
