The generation of electrical energy from diesel generator sets is based on the same principle as that of hydroelectric power generation, thermal power generation, wind power generation and other power generation equipment - electromagnetic induction principle.

A part of the conductor in a closed circuit moves through a magnetic field to cut magnetic induction lines, and an electric current is generated in the conductor. This phenomenon is called electromagnetic induction. The generated current is called induced current.

In a diesel generator set, the diesel engine generates a certain amount of power by burning the mixed air. Inside the AC generator, there are armature windings and excitation windings or permanent magnets. The armature winding is the conductor, and the excitation winding or permanent magnet is capable of generating a magnetic field. Therefore, by driving the generator armature winding, excitation winding, or permanent magnet to rotate through the power of the diesel engine, using the principle of "electromagnetic induction", the generator will output induced electromotive force, which can generate current through the closed load circuit.

Therefore, in simple terms, the principle of diesel generator set power generation is that the diesel engine transfers mechanical energy to AC power generation, causing the closed circuit inside the generator to cut magnetic lines relative to the magnetic field inside the generator, and generate electrical energy.