An improved branch current-based three-phase state estimation algorithm for distribution systems with DGs

The penetration of distributed generations (DGs) in distribution system has been steadily increasing. This paper develops and tests a three-phase-based state estimation algorithm for distribution system with DGs. This algorithm is based on branch currents. The amplitudes and phase angles of branch currents are selected as state variables. A proper change of measurements enables the three-phase distribution system to be decoupled and results in better performance. In addition, DGs are classified into four types and treated as real-time measurements with different information. Different methods are applied to deal with different types of DGs in the state estimation. The proposed algorithm is tested and validated using the IEEE 13-node test distribution system. The impact of different types and different locations of the DGs are studied.