Three-Phase Voltage Stabilizer for 10/0.4 kV Transformer Substations and Analysis of its Control Methods
The problem of improving the quality of voltage for three-phase electricity consumers when they are powered from transformer substations, including complete transformer substations, with a voltage of 10/0.4 kV is considered and a comparative analysis of existing three-phase voltage stabilization devices is performed. Their main disadvantages are revealed. A variant of the power circuit without an input converter transformer and the connection of a three-phase voltage stabilizer to the secondary winding of the main transformer of the substation is proposed, which allows minimizing its mass-dimensional parameters. The stabilizer is a low-power block-modular thyristor-transistor channel containing a high-frequency link that provides the formation and regulation of the voltage of the voltage booster for the load together with the voltage of the main transformer of the substation. A step-down transformer operating at a frequency of 450 Hz is used as a link of increased frequency. The paper provides a brief description of the scheme and principle of operation of the proposed three-phase voltage stabilizer as well as ways to control it. The construction of the adjustment characteristics and the harmonic analysis of the load voltage for these control methods are performed. Analytical relations are obtained for the current voltage on the load during stabilization, its first harmonic and average value, respectively, when the amplitude is regulated by a reverse rectifier and pulse-width regulation by a voltage inverter. Simulation of the device operation in various operating modes, namely, at low voltage in the network and at load, and at high voltage in the network and at load, was performed. Some results of simulation modeling in the Matlab/Simulink software environment are presented. Conclusions on the work are made.