一种具有电压支撑功能的改进无功注入策略

电压跌落是输配电系统面临的最严重的问题之一。随着分布式光伏电源在电力系统中的渗透率越来越高,国内外最新标准要求光伏逆变器必须具备低电压穿越能力。为了消除有功功率振荡,在传统的正/负序控制基础上提出了一种改进的有功/无功注入策略；针对现有电压支撑方法缺乏电压抬升范围控制,将三相电压幅值作为控制目标,详细推导了适用于不同电压跌落情况下的数学模型,得出为保证各相电压均保持在安全运行范围之内所需注入无功功率参考值。仿真结果验证了所提策略的正确性和有效性。

An Improved Reactive Power Injection Strategy with Voltage Limits

Voltage drop was one of the most serious problems for the operation of the transmission and distribution networks. With the growing penetration level of distributed photovoltaic power sources, the latest domestic and international standards require that the PV inverter must have low voltage ride through capability. In order to eliminate the active power oscillations, an improved active/reactive current injection strategy was proposed on the basis of the conventional positive/negative sequence control. As the current voltage support schemes fail to limit voltage lifting range, a complete control scheme intended to regard three phase voltage amplitudes as the control target to regulate the maximum and minimum phase voltages at the point of common coupling within the limits established in grid codes for continuous operation. A mathematical model adapted to different types of voltage dips was derived in detail and reactive power reference was also calculated after that. Finally, the results of simulation confirmed the correctness and effectiveness of the proposed strategy.