Topology Identification in Distribution Systems Using Line Current Sensors: An MILP Approach

This study is motivated by the recent advancements in developing non-contact line sensor technologies that come at a low cost, but have limited measurement capabilities. While they are intended to measure current, they cannot measure voltage and power. This poses a challenge to certain distribution system applications, such as topology identification (TI), because they commonly use voltage and power measurements. To address this open problem, a new TI algorithm is proposed based on measurements from a few line current sensors, together with available pseudo-measurements for nodal power injections. A TI problem formulation is first developed in the form of a mixed integer nonlinear program (MINLP). Several reformulation steps are then adopted to tackle the nonlinearities to express the TI problem in the form of a mixed integer linear program (MILP). The proposed method is able to identify all possible topologies, including radial, loop, and island configurations, which extends the application of TI to identify switch malfunctions and to detect outages. In addition, recommendations are made with respect to the number and location of the line current sensors to ensure performance accuracy of the TI method. A novel multi-period TI algorithm is also proposed to use multiple measurement snapshots to improve the TI accuracy and robustness against errors in pseudo-measurements. The effectiveness of the proposed TI algorithms is examined on the IEEE 33-bus test case as well as a test case based on a real-world feeder in Riverside, CA.