Working Principle of High Voltage Synchronous Generator

by Starlight Generator dieselgeneratortech

The generator set is a power generation device that is composed of a synchronous generator, a drive machine, a control, and an accessory device. The uninteruptible power supply system of modern data and communication enters widely uses medium and high power diesel generator sets as backup power sources for utility power. Their rated output line voltage is 400V, phase voltage is 230V, which belongs to the secondary distribution network voltage category, that is the low voltage section in China’s transmission network system. These diesel generator sets can also be referred to as low voltage power generation groups.

Basic working principle of high voltage principle

The basic working principle of a high voltage generator is the same as that of low voltage generator set. Generally, the diesel engine drives the synchronous generator to work together under the cooperation of accessory device and the controller to generate electricity. The output power of low-voltage generator sets is more than ten to several thousand kVA, and the output power of high-voltage generator sets is more than one thousand kVA. There are also a small number of high-voltage generator sets that use gas turbines to drive synchronous generators. However, regardless of the type of engine used as the drive machine, their spindle speed should be set at 1500 rpm. This is to ensure that the three-phase synchronous generators are capable of emitting 50 Hz AC per second in accordance with national regulations.

The winding coil on the synchronous generator rotor generates a DC rotor magnetic field after passing a direct current, and its strength is represented by a magnetic flux Φ. When the rotor is rotated by the engine, the magnetic field of the rotor cuts the winding embedded in the stator of the synchronous generator during the rotation (the wire is called a turn around one turn. There is an N turns coil in each winding), and the two ends of the winding are included. Electromotive force E. The stronger the rotor flux Φ, the more the number of turns of the stator winding coil N, the higher the voltage generated. They synchronous generator has three (three-phase) stator windings, and the effective value of the induced electromotive force E of each winding is: E=4.44ΦfNK.

Where f is the frequency of the synchronous generator output voltage 50Hz, K is the ratio of the number of the full-circle coil to the short-distance coil in the stator winding, called the pitch factor, usually K ≤ 1. It can be seen that in order to make the synchronous generator emit a higher voltage, the magnetic flux Φ of the rotor magnetic field can be increased in a two-pronged manner and the number of turns N of the stator winding can be increased. High-voltage synchronous generators are manufactured according to this technical concept. With the gradual improvement of motor manufacturing technology and the continuous emergence of new material, the technical performance of modern high-voltage synchronous generators has become more and more perfect.