三相电压不对称跌落光伏并网逆变器控制方法

为了满足光伏并网逆变器在三相电网电压不对称跌落情况下的低电压穿越能力的要求,提出了一种电流正负序同步旋转坐标独立控制的方法,以抑制负序电流和并网电流谐波,使得光伏并网逆变器在三相电网电压不平衡跌落过程中能够正常运行,且不影响电网电能质量。特别地,对电网电压正负序分量的检测进行了详细研究,分析了两种不同的电网正负序分量检测方法的优缺点,优选一种方法进行了实验验证。所提出的低电压穿越控制方法通过了国家电网的零电压穿越认证,证明了该技术方案的有效性。

Control method of photovoltaic grid-connected inverter under three-phase voltage unbalanced dips

To meet the requirements to low voltage ride-through (LVRT) capability of photovoltaic grid-connected inverter under three-phase voltage unbalanced dips, this paper proposes a current positive sequence synchronous rotational coordinate independent control method. In the strategy, the positive and negative sequence component is controlled independently. So that the negative sequence current and the grid current harmonics can be retrained. So the photovoltaic grid-connected inverter can work well at LVRT situation, and shall not affect the power quality of power grid. The positive and negative sequence component detection of the grid voltage are studied in detail and the pro and con of two detection methods are analyzed and one of them is selected and verified. The LVRT method proposed has passed the no voltage ride-through certification, which verifies the effectiveness of the proposed technical solution.