Energy-efficient phase-shifting transformers for rural power systems with solar PV energy sources: the state-of-the-art survey, artificial intelligence-based approach and a case study

Abstract

Integration of renewable energy sources (RESs) into electric power grids is increasing day by day. In the world, solar energy potential is at a high level among RESs. Thus, solar PV power plant installations are increasing in many countries. These RESs can bring huge problems to the rural power system grid such as transmission lines congestion. Due to the causative factors nature, congestion can continually happen and maintain for a long commutative time. Thus, transmission efficiency is a key factor when relieving congestion. Phase-shifting transformers (PSTs) can remove these congestions. Compared to other power flow controllers, phase-shifting transformers have advantages in rural power systems such as flexibility and economic characteristic. A phase-shifting transformer controls power flow by changing the phase shift angle between the sending and receiving ends. PST increases the transmission capacity of the power system. A comprehensive study is carried out for the proper selection of the appropriate phase-shifted transformer to improve power quality and energy efficiency, and to ensure grid reliability and power flow control in smart grids emerged with the integration of renewable energy plants into electric grids. This chapter proposes a review of PSTs, consisting of classifications of PST studies and applications according to power rating, types of configurations and winding connection of PST, control and optimization techniques used for PSTs and power systems with PSTs, protection techniques and parallel operation of phase-shifting transformers in literature. A dynamic model of a solar PV power plant integrated with a 10-stage 50 MVA 380-V/154-kV phase shift transformer is presented. Also, artificial intelligence-based apparent power estimation analysis of a PST is realized using manufactured 150 MVA 330/161-kV PST for rural power systems. FANN and PSO-FANN hybrid estimation methods are used to estimate the apparent power of the PST. This study aims to contribute to researchers and application engineers with a comprehensive perspective on the status of PST studies. A list of more than 150 references on the subject will also be added for quick reference.