Practical steady-state security region of loop-containing active distribution networks

With the wide spread of distributed generators (DGs), distribution networks are evolving into loop-containing networks to accommodate DGs better, which brings challenges to the steady-state security analysis. For loop-containing active distribution networks (LADNs) with massive DGs (large quantity and capacity), this paper defines a new practical steady-state security region (PSSR) where the power flow can be managed securely within the practical possible decision variable ranges of engineering. Lots of simulation has validated the fact that the PSSR boundaries can be approximated by hyperplanes (HPs), and based on which a new analytical calculation method of the PSSR boundaries is proposed: The equivalent impedances of loop-containing networks are first generated based on the two-port network model. And then after a series of corrections based on power flow calculations, we have the HP expressions of the PSSR boundaries, which are accurate enough in practical engineering and the calculation time is sub second for common system sizes. Thus, the proposed method is a helpful tool for the real-time security analysis in the LADNs with massive DGs.