How to adjust the phase-shifting transformer

Phase-shifting transformer is a special power transformer, which is widely used in power system, mainly for regulating voltage, controlling power flow and improving system stability and power quality. It can adjust the voltage and power by changing the phase angle between the primary side and the secondary side, so it is called "phase-shifting transformer". This paper will mainly introduce the working principle and adjustment method of phase-shifting transformer.

First, the basic working principle of phase-shifting transformer

A phase-shifting transformer usually consists of a main transformer and an additional regulating winding. Its core function is to change the magnitude and phase of output voltage by adjusting the ratio of transformer or introducing phase shift. Different from ordinary transformers, phase-shifting transformers can not only change the amplitude of voltage, but also affect the active power flow of the system by changing the phase angle of voltage.

In high voltage transmission lines, the voltage phase difference between different nodes will affect the power distribution because of the existence of line impedance. The phase-shifting transformer redistributes the active power flow in the system by artificially introducing a controllable phase difference, so as to optimize the operation of the power grid.

Second, the main adjustment mode of phase-shifting transformer

The adjustment modes of phase-shifting transformer mainly include the following:

1. Mechanical adjustment
This is the most traditional way to adjust the voltage or phase by changing the tap-changer position of the transformer manually or electrically. Although the structure is simple and the cost is low, the response speed is slow, which is suitable for occasions with low adjustment frequency.

2. Thyristor control regulation
The output voltage and phase of the transformer are adjusted by the control circuit composed of thyristor and other power electronic devices. This method has fast response speed and high adjustment precision, and is suitable for dynamic adjustment systems that need fast response.

3. Phase-angle Control.
In HVDC system, phase control is often used to adjust the phase-shifting transformer. By controlling the trigger angle, the working state of rectifier or inverter is changed, thus indirectly controlling the output phase and voltage of transformer.

4. Adjustment of digital control system
With the development of power electronics technology and automation control technology, modern phase-shifting transformers increasingly adopt digital control systems based on microprocessors or PLC. This method can not only realize accurate voltage and phase adjustment, but also realize information interaction with other power system equipment and improve the intelligent level of the system.

Third, the adjustment strategy in practical application

In actual operation, the adjustment strategy of phase-shifting transformer is usually dynamically adjusted based on the operating state of the system. For example:

-In systems with large load changes, the phase shift angle can be automatically adjusted by monitoring the changes of voltage and current in real time to maintain voltage stability;
-In a multi-power grid-connected system, the phase-shifting transformer can be used to adjust the power distribution between different power sources to prevent overload;
-In the power market environment, phase-shifting transformers can also be used for power flow control, optimizing power transaction paths and reducing transmission losses.

IV. Conclusion

With the development of modern power system towards intelligence and high efficiency, phase-shifting transformer, as a key regulating device, is becoming more and more important. Through effective adjustment of phase-shifting transformer, voltage stability, power flow optimization and operation efficiency of power system can be realized. In the future, with the development of smart grid and new energy technology, the regulation technology of phase-shifting transformer will continue to improve, which will provide strong support for building a safer, more efficient and greener power system.