Quantification of distribution network security with high penetration of distributed generators

Abstract

With the access of distributed generators (DGs), it is increasingly difficult to deal with the uncertainties of DG outputs. It is more important to maintain the secure operation of distribution networks (DNs). The power supply and load demand cannot balance at node. Therefore, the imbalanced energy are further transported in branches and feeders, which leads to the complex and uncertain characteristics of the whole DN. The cooperation of power electronic devices provides opportunities to maintain the security of DN. However, it is difficult to coordinate and schedule multiple types of controllable devices. In which reason the controllable devices cannot effectively improve the security of DN. In this paper, to generally quantify the security of DN, the power balance at node is considered firstly. Then the security of network is further discussed, including constraints of line power and node voltage. After that, security is quantified by evaluation indexes in the aspects of amplitude, frequency and intensity. Additionally, the improvement of system security brought by controllable devices are evaluated by the proposed indexes. Finally, IEEE 33-node system is adopted to conduct the case study. Results show that with the integration of controllable devices, the system security is effectively improved.