Mathematical Models And Power Flow Control Of Thyristor Controlled Interphase Power Controller

With the growth of electricity consumption, the transmission-line system of electric power is essentially tending to be interconnected together. In order to make full use of the economic benefit of the interconnected power system, the power flow of tie-line should be flexibly controlled, realizing the economic dispatch in the steady state and not contributing to increasing short-circuit levels in faults. Because of the control characteristic of the power and the fault insulation, interphase power controller, a device of FACTS family, is adapted to act as the AC tie-line.Disturbance among the interconnected power system is easily to cause the tie-line power flow and voltage to fluctuate, which is more serious to those connected by IPC with high impedance. The paper is aimed to research how the IPC to control the tie-line power flow after disturbance. In order to control power flow in flexible and rapid, IPC is reformed to thyristor controlled interphase power controller, whose parameters, inductor and capacitor, are controlled by thyristor.Based on the simple structure, the principle of the power control and the fault insulation of IPC is introduced. And then, the mathematical expression between trigger-delayed angle of thyristor and the equivalent susceptance on inductive branch is deduced based on the simple structure of TCIPC. The principle of trigger circuit of the thyristor is illuminated by MATLAB simulation system.Furtherly, considering the influence of equivalent parameters of power networks, the mathematical expression between trigger-delayed angle of thyristor and parameters of TCIPC as well as the Thevenin-equivalent parameters of interconnected networks is deduced, and the relation between power control and parameters of TCIPC is analyzed.Finally, the question of the relative phase slippage on the both sides of interconnected power system connected by tie-line with IPC is presented. Insuccession, the adjustment characteristic of TCIPC is studied based on harmonious parameters with the P-Q curve of TCIPC. The example shows that the active power fluctuation can be avoided and the voltage quality can be assured during the angle slippage between sending and receiving network by coordinating inductive and capacitive values.