Unbalanced multi‐phase distribution grid topology estimation and bus phase identification. Issue 4 (13th August 2019)

• Record Type: Journal Article
• Authors: Liao, Yizheng; Weng, Yang; Liu, Guangyi; Zhao, Zhongyang; Tan, Chin‐Woo; Rajagopal, Ram
• Is Part Of: IET smart grid. Volume 2:Issue 4(2019)
• Page Start: 557
• Page End: 570
• Publication Date: 2019-08-13
• Subjects: power distribution control -- load flow -- smart power grids -- distribution networks -- distributed power generation -- power grids -- learning (artificial intelligence) -- power distribution economics -- power distribution planning -- smart meters; bus phase identification -- distributed energy resources -- accurate multiphase topology -- unbalanced distribution networks -- topology knowledge -- low‐voltage distribution grids -- bus phase labelling information -- multiphase unbalanced systems -- radial multiphase structure -- incorrect bus phase labels -- bus phase connection; B0260 Optimisation techniques -- B8110B Power system management, operation and economics -- B8110D Power system planning and layout -- B8120J Distribution networks -- C3340H Control of electric power systems -- C6170K Knowledge engineering techniques -- B8120K Distributed power generation; Smart power grids -- Periodicals; Computer science -- Periodicals; Energy industries -- Periodicals; Broadcasting -- Periodicals; 333.79110285
• DOI: 10.1049/iet-stg.2018.0291
• Languages: English
• ISSNs: 2515-2947

Abstract

Abstract : 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. Also, the bus phase labeling information is inaccurate due to human errors or outdated records.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.