基于图论的光伏系统多功率模块优化控制策略

In order to solve the problems of uneven power distribution and easy influence of DC bus voltage in multi-power modules of photovoltaic system, a optimal strategy for multi-power module control of photovoltaic system based on graph theory was designed which improves the limitations of traditional droop control on the regulation of multi-branch photovoltaic systems. Firstly, based on the theory of tracking synchronization and coordination synchronization in graph theory, a consensus algorithm was constructed, and a secondary optimization controller for photovoltaic system was designed. Then, the Lyapunov function was used to prove the finite time convergence stability of the designed controller. Finally, three power modules with the same capacity are taken as an example to run in parallel, and the simulation analysis and experimental verification were carried out. Experimental results showed that the proposed optimal control strategy can quickly restore the DC bus-side voltage of the photovoltaic system to within the error range of ±5% of the rated value when the load changes(3 times faster than conventional sag control), and has smaller spikes, and compared with the traditional droop control strategy, the output current deviation of each power module is greatly reduced (less than 2%), and the balanced distribution of each power module of the system is effectively realized.