分布式屋顶光伏接入下并网功率平衡控制方法

Control Method of Grid-Connected Power Balance under Distributed Rooftop Photovoltaic Access

由于逆变器间电流的有效值相差较大,传统的分布式屋顶光伏接入下并网容易出现失衡问题。提出一种分布式屋顶光伏接入下并网功率平衡控制方法。根据分布式屋顶光伏接入并网原理,建立分布式屋顶光伏接入并网结构模型,确定光伏阵列和逆变器的数学模型;采用矢量图表达分布式屋顶光伏接入并网功率平衡变化,确定并网零序电压与逆变器三相输出电压之间的矢量关系;计算逆变器三相额定功率、三相功率误差及零序分量的幅值和相位,设计零序分量叠加的逆变器相间功率控制框图,使逆变器相间功率平衡。确定仿真参数,设置实验工况条件,仿真控制结果:在并网功率失衡不严重的工况1条件下,该文研究方法的电流有效值相差±0.01 A,小于其他2种对比方法;在并网功率失衡严重的工况2条件下,该文研究方法的电流有效值相差±0.02 A,远小于其他2种对比方法。说明该文方法的控制性能优于其他2种对比方法,具有较大的应用价值。

Due to the large difference in the effective value of current between inverters,the grid connected under the traditional distributed roof photovoltaic access is prone to imbalance.To this end,a grid connected power balance control method under the distributed roof photovoltaic access is proposed.According to the principle of distributed roof photovoltaic access and grid connection,the structural model is established,and the mathematical model of photovoltaic array and inverter is determined.The vector diagram is used to express the change of grid connected power balance of distributed roof photovoltaic access,and the vector relationship between grid connected zero sequence voltage vector and three-phase output voltage of inverter is determined;The inverter three-phase rated power,three-phase power error,amplitude and phase of zero sequence component are calculated,and the inverter phase-tophase power control block diagram superimposed by zero sequence component is designed to control the inverter phaseto-phase power balance.The simulation parameters are determined and the experimental working conditions are set.The simulation control results are as follows:under the condition of working Condition 1 with no serious grid connected power imbalance,the difference of current effective value of the research method in this paper is±0.01 A,which is less than that of the other two comparison systems;Under the condition of Condition 2 with serious grid connected power imbalance,the difference of current effective value of the research method in this paper is±0.02 A,which is much smaller than the other two comparison systems.The control performance of the research method in this paper is better than the other two comparison methods,and it has great application value.