Hybrid control for high-penetration distribution grid based on operational mode conversion

For the purpose of developing smart control with a great degree of flexibility to enhance the stability, security and self-healing capability of a high-penetration distribution grid, in this study smart control called a hierarchical hybrid control is proposed based on operational mode conversions of distributed energy resources. Corresponding to the hybrid dynamic behaviours of the system, the hierarchical hybrid control consists of discrete control strategies at the upper level, local continuous controllers at the lower level and their interactions. The upper level discrete control strategies are mainly responsible for switching operational modes so as to enhance security and self-healing capability during significant disturbances. The lower level continuous control aims to regulate dynamic stability of each controlled unit in order to obtain satisfactory performance. The effectiveness of the proposed hybrid control is demonstrated through simulation examples.