Evaluation Method of the Power Grid Unbalance Factor under Cooperative Distribution of Photovoltaic and Energy Storage

Abstract

With the rapid evolution of electrification, a number of asymmetric loads appear in the power system, making three-phase unbalanced pollution of the power grid increasingly serious. However, there are currently no comprehensive evaluation indexes to assess the unbalanced factor between power grids and customers, which makes it tough to locate and control unbalanced pollution sources. To solve the conundrum, the paper first summarizes the traditional assessment indexes and points out their shortcomings. Then, according to IEEE Std 1459-2010 power theory, the apparent fundamental power is represented by sequence components and propose a set of new evaluation indexes and methods of unbalanced factor. Finally, to verify the practicability and accuracy of the new indexes, simulation models of different wiring forms are constructed in MATLAB, and the simulation experiment results are analyzed. The results show that compared with the existing indexes, the new indexes can comprehensively reflect the unbalanced pollution factor of the system and the customer side under different wiring forms. They can be used to locate the unbalance sources and divide the unbalanced responsibilities.