Cheng Yuhua, Chen Kai, Bai Libing, Yang Jing
School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054, China.
Rev Sci Instrum. 2014 Feb;85(2):025110. doi: 10.1063/1.4866023.
Precise control of the grid-connected current is a challenge in photovoltaic inverter research. Traditional Proportional-Integral (PI) control technology cannot eliminate steady-state error when tracking the sinusoidal signal from the grid, which results in a very high total harmonic distortion in the grid-connected current. A novel PI controller has been developed in this paper, in which the sinusoidal wave is discretized into an N-step input signal that is decided by the control frequency to eliminate the steady state error of the system. The effect of periodical error caused by the dead zone of the power switch and conduction voltage drop can be avoided; the current tracking accuracy and current harmonic content can also be improved. Based on the proposed PI controller, a 700 W photovoltaic grid-connected inverter is developed and validated. The improvement has been demonstrated through experimental results.
精确控制并网电流是光伏逆变器研究中的一项挑战。传统的比例积分（PI）控制技术在跟踪电网的正弦信号时无法消除稳态误差，这导致并网电流中的总谐波失真非常高。本文开发了一种新型PI控制器，其中正弦波被离散化为由控制频率决定的N步输入信号，以消除系统的稳态误差。可以避免由功率开关的死区和导通电压降引起的周期性误差的影响；还可以提高电流跟踪精度和电流谐波含量。基于所提出的PI控制器，开发并验证了一台700W的光伏并网逆变器。实验结果证明了这种改进。
