Section Load Estimation Method for a Distribution System Using Constant Current Load Model

The section load corresponds to the total load in a section that is surrounded by a circuit breaker（CB) and/or automatic switches (ASWs). Because various applications provided by an advanced distribution management system, such as volt/var optimization and dynamic network reconfiguration, require accurate distribution system model including the power consumption of loads, the importance of the accurate section load estimation is increasing. If the active and reactive power measurements are accurate, the section load can be estimated with simple methods. However, the voltage magnitude measured by an ASW is often inaccurate, leading to erroneous active and reactive power measurements. Thus, only the current magnitude and the power factor angle, which are more accurate, are generally used to estimate the section load in the actual system. The main idea of the proposed method is that the reliable measurements of ASWs correspond to the parameters for a constant current load model, i.e., current magnitude and power factor angle. Therefore, ASWs can be modeled as constant current loads in the estimation problem. Based on this idea, a new section load estimation method is proposed, utilizing the forward/backward sweep power flow method, which is easy to incorporate with the constant current load model. Simulation results verify that the accuracy of the section load estimation is improved with the proposed method compared to a conventional method.