Unbalanced Multi-Phase Distribution Grid Topology Estimation and Bus Phase Identification
This addresses the need for accurate grid monitoring and control for utilities managing uncertainties from distributed energy resources, though it is incremental as it builds on existing algorithms like Chow-Liu.
The paper tackles the problem of estimating multi-phase topology and identifying bus phase connections in unbalanced distribution grids, where such information is often unavailable or inaccurate, by proposing an information-theoretic approach using smart meter data and proving that the Chow-Liu algorithm can accurately find the topology, with simulation results showing high accuracy even under strong load unbalancing and distributed energy resources.
There is an increasing need for monitoring and controlling uncertainties brought by distributed energy resources in distribution grids. For such goal, accurate multi-phase topology is the basis for correlating measurements in unbalanced distribution networks. Unfortunately, such topology knowledge is often unavailable due to limited investment, especially for \revv{low-voltage} distribution grids. Also, the bus phase labeling information is inaccurate due to human errors or outdated records. For this challenge, this paper utilizes smart meter data for an information-theoretic approach to learn the topology of distribution grids. Specifically, multi-phase unbalanced systems are converted into symmetrical components, namely positive, negative, and zero sequences. Then, this paper proves that the Chow-Liu algorithm finds the topology by utilizing power flow equations and the conditional independence relationships implied by the radial multi-phase structure of distribution grids with the presence of incorrect bus phase labels. At last, by utilizing Carson's equation, this paper proves that the bus phase connection can be correctly identified using voltage measurements. For validation, IEEE systems are simulated using three real data sets. The simulation results demonstrate that the algorithm is highly accurate for finding multi-phase topology even with strong load unbalancing condition and DERs. This ensures close monitoring and controlling DERs in distribution grids.