Distribution Load Capability With Nodal Power Factor Constraints

Unity power factor (PF) injections through distributed grid-tie inverters reduce net real power demand at distribution substations. This reduces line utilization, but can also result in undesirable PFs within the system. PF constraints, therefore, may limit injection or “load” capability (LC) in circuits with growing distributed resource penetration. Therefore, this work presents a PF-based estimator of LC for distribution systems, which can be appended to existing LC formulations without additional inputs. A solution algorithm is provided, and simulation results are presented for an actual 2556-node distribution system. An increase in distributed photovoltaic injections resulted in reduction of overall system LC due to substation PF constraints. Finally, series acceleration is investigated for LC problems; in the tested cases, the acceleration technique reduced the number of iterations for a current-based LC estimator by an average of 85%.