Voltage Estimation in Power Distribution Networks Using Advanced Metering Infrastructure-Based Correction and a Virtual Voltage-Drop Reference for Switching Sections

Abstract

This paper presents a method to correct errors in real-time voltage measurements in a power distribution network based on advanced metering infrastructure (AMI) data and to determine the real-time voltage condition of all buses from the corrected voltage. It focuses on two aspects. First, for voltage measurement in medium-voltage distribution networks, the causes and characteristics of errors in the commonly used capacitor voltage divider method are analyzed, and such errors are shown to exhibit identifiable patterns. On this basis, coefficients are derived offline to correct errors in voltage measurements using seasonal and time-of-day patterns obtained from AMI data. Second, this study addresses issues arising from modeling distributed loads in actual distribution systems as lumped-load representations and from error accumulation in voltage estimation due to reliance on pseudo-measurements. Accordingly, a voltage-estimation method is proposed for online operating conditions, in which a virtual sectional voltage-drop reference point is shifted according to the corrected voltage measurements. The proposed method was implemented in the advanced distribution management system of the Korea Electric Power Corporation, and a case study was conducted by using long-term data from an actual distribution network. The method was highly effective in reducing both average voltage-estimation error and instantaneous errors. In particular, the error reduction was significant during periods when the distributed generation output had a strong influence. The proposed method is directly applicable to actual distribution networks because it fully accounts for the non-real-time constraints of AMI data while excluding additional equipment and assumptions currently introduced into distribution systems.