Application of double core symmetrical phase shifting transformer in power flow regulation of UHV power grid

Abstract

With the development of society, the demand for electric energy is growing day by day. However, the energy centers and load centers are geographically distributed in a reverse direction, so the power supply and demand are unbalanced. High voltage transmission lines are characterized by long distance and large capacity, and the power flow problems are increasingly prominent. In order to flexibly adjust the line power flow, improve the comprehensive utilization of grid assets, and improve the transmission capacity of the system, this paper analyzes the principle of double core symmetrical phase-shift transformer (DS-PST) and the application of power flow regulation. Firstly, the basic principle of phase shifting transformer is analyzed in detail, and the equivalent mathematical model of DS-PST and the calculation of main parameters are derived. Impedance coefficient and excitation coefficient are introduced to modify the parameter design of DS-PST. Then, an electromagnetic simulation model is established to verify the effectiveness of the design method. Finally, a system simulation model is built to verify the power flow regulation effect of DS-PST by taking 500 kV UHV power grid and IEEE standard multi-node system as examples. DS-PST can transfer the active power transmitted by the lines with high load rate to the lines with low load rate, which makes the power flow distribution of the system more balanced and effectively improves the transmission capacity of the power system.

Keywords

• Active power flow
• Phase shifting transformer (PST)
• Energy transmission
• On load tap changer (OLTC)