光伏并网系统中直流注入问题最新进展及发展趋势

The progress and development trend of the DC injection issue in PV grid-connected systems

限制光伏发电系统并入大电网时直流电流的含量是光伏并网的重要需求。国内外相关标准对光伏并网电流中直流分量的大小有所规定。随着非隔离型光伏并网逆变系统的推广,目前直流注入问题日益受到重视。结合相关文献介绍了直流注入产生的原因及所带来的不利影响,从解决直流注入问题的原理出发,将目前已提出的解决方法归纳为三类:采用可抑制直流注入的逆变器、检测补偿法以及电容隔直法。通过理论分析对各类方法的原理进行了介绍,说明了各自存在的优点和不足,通过相互比较进一步总结了各类方法的特点。最后,对光伏并网系统中直流注入问题解决方法的发展前景作了展望。

Limitation of direct current （DC） injection into the network is an important requirement for grid-connected photovoltaic （PV） systems. The DC component in the grid-connected current of PV systems is specified by domestic and international standards. With the promotion of the non-isolated PV grid systems, the DC injection problem has been increasingly concerned. According to related articles, the causes and the adverse effects of DC injection are introduced. The proposed solutions are classified into three categories by the theory of solving the DC injection problem： the DC current suppressed inverters, detection and compensation method and capacitor blocking method. The principle of each method is presented, and their advantages and disadvantages are stated. The characteristics of various methods are further summarized by comparisons. Finally, the prospect of the resolvent for DC injection in PV grid-connected systems is also made.