孤岛运行时逆变器并联改进下垂控制策略

Improved Droop Control Strategy for Multi-inverter in Parallel During Island Operation

功率均衡与准确的分配是多逆变器并联控制中的一个关键问题。在稳态工作点附近,由于功率的波动会引起电压和频率的偏差,传统下垂控制无法对不同功率偏差进行灵活控制。为提高系统灵活性、缩小功率偏差对系统的影响,提出一种改进功率下垂控制策略。通过在下垂公式中引入修正项函数,对原有下垂特性进行调整,改善下垂控制的性能,提高系统的快速性和稳定性。最后通过搭建两台逆变器并联孤岛运行仿真模型验证了所提方法的正确性和有效性。

Power equilibrium and its precise allocation is critical in multi-inverter parallel control. As power fluctuation might lead to voltage and frequency deviations in the proximity of the steady state working point, traditional droop control could not perform flexible control over different power deviations. To improve system flexibility and reduce the affection of power deviation upon the system, this paper proposed an improved power droop control strategy. The correction term function was introduced in the droop formula to adjust the original droop characteristics so as to improve the performance of droop control and raise system rapidity and stability. Finally, the correctness and validity of the proposed approach was verified through two simulation models established for the island operation of parallel converters.