不平衡情况下逆变型分布式电源并网控制策略研究

摘要

In the case of unbalanced power grid, the grid-connected inverter with traditional control strategies will produce a large amount of harmonics at both the dc side and ac side, and then lead to fluctuations in power and performance deterioration. Therefore, more effective control is needed to improve the capability and functionality of grid-connected inverter interfaced distribute generator (IIDG). To overcome the problem, this paper analyzes the impacts of different control objectives on the inverter output power and grid-connected current, presents a unified reference current vector expression, and proposes a control method that combines the dual current control loop for positive and negative sequence and linear reactive power control. The control strategy can effectively suppress the grid current harmonic, adjust the voltage at the point of common coupling, reduce the unbalance of the system, and the ability of the inverter is enhanced. The simulation results validated the effectiveness of the proposed method.%在电网不平衡情况下，基于传统控制策略的并网逆变器将在直流侧和交流侧产生大量谐波，导致功率大幅波动，系统性能恶化，因此并网逆变器的有效控制，对提高逆变型分布式电源并网能力具有重要意义。针对上述问题，本文提出了一种电压不平衡跌落下的线性无功功率控制策略。首先分析了不同控制目标对逆变器并网输出功率和电流的影响，建立统一参考电流矢量表达式，然后结合正负序双电流独立内环控制，应用瞬时功率理论，实现所提出的控制策略。该控制策略在电网不平衡跌落情况下能有效抑制并网电流谐波，调整并网点电压，降低系统不平衡度，从而提高逆变器并网能力。仿真结果验证了所提出方法的有效性和适用性。