基于FBD法的光伏并网系统谐波和无功电流的检测与补偿

Method for detection and compensation of harmonics and reactive current in the grid-connected PV system based on FBD method

基于光伏并网发电系统和并联型APF在拓扑结构、运行方式和控制方法等方面有诸多相同点,提出一种将有源滤波和无功功率补偿与光伏并网发电相结合的一体化系统。为了检测该供电系统中的谐波和无功电流,提出了一种基于FBD法的检测方法。该方法测量电压相位产生参考电压来做投影变换,利用等效电导对负载电流进行分解,计算出基波正序有功、无功及谐波电流分量。与基于瞬时无功功率理论的电流检测方法相比,该方法没有复杂的Park变换和d-q变换,可以更加快速有效地进行电流实时检测,并且可以灵活应用于三相不平衡供电系统。仿真结果表明了该电流检测方法的正确性和有效性。

Based on the similarities of the grid-connected PV system and the parallel APF in the topological structure, operation mode and control method, this paper put forward a new integration system, which combined active filter and reactive power compensation with grid-connected PV generation. In order to detect the harmonics and reactive current of the power supply system, a detection method based on FBD was proposed. By measuring the voltage phase, a refer- ence voltage was generated for the projection transformation. By using the equivalent conductance to decompose the current, the fundamental positive sequence active and reactive current and the harmonics current were calculated. Compared with the current detection method based on the theory of instantaneous reactive power, this method has no complex Park transformation and d-q transformation, so it can detect the real-time current more quickly and effective- ly. In the meanwhile, it can be flexibly applied to the unbalanced three-phase power supply system. The simulation results showed the correctness and effectiveness of the proposed detection method.