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Principle and development direction of diesel generator

Principle and development direction of diesel generator

We at ITCPOWER will briefly describe the principle and development direction of diesel generators. Let more people know about us.

The basic structure of diesel generator is composed of diesel engine and generator. The diesel engine is used as power to drive the generator to generate electricity.

The basic structure of a diesel engine is composed of cylinders, pistons, cylinder heads, intake valves, exhaust valves, piston pins, connecting rods, crankshafts, bearings and flywheels. The diesel engine of the diesel generator is generally a single-cylinder or multi-cylinder four-stroke diesel engine. Below we will only talk about the basic working principle of the single-cylinder four-stroke diesel engine: the starting of the diesel engine is to rotate the crankshaft of the diesel engine by manpower or other power to make the piston reciprocate up and down in the top closed cylinder. The piston completes four strokes in motion: intake stroke, compression stroke, combustion and work (expansion) stroke, and exhaust stroke.

When the piston moves from top to bottom, the intake valve opens, and the fresh air filtered by the air filter enters the cylinder to complete the intake stroke. The piston moves from bottom to top, the intake and exhaust valves are closed, the air is compressed, the temperature and pressure increase, and the compression process is completed. When the piston is about to reach the top, the injector sprays the filtered fuel into the combustion chamber in the form of a mist and mixes with the high-temperature and high-pressure air, which immediately ignites and burns by itself. The formed high pressure pushes the piston downward to do work, pushes the crankshaft to rotate, and completes the work stroke. After the power stroke is completed, the piston moves from bottom to top, the exhaust valve opens to exhaust, and the exhaust stroke is completed. Each stroke crankshaft makes half a revolution. After several working cycles, the diesel engine gradually accelerates into work under the inertia of the flywheel.

The rotation of the crankshaft of the diesel engine drives the generator to rotate and generate electricity. Generators have DC generators and alternators.

The DC generator is mainly composed of a generator shell, a magnetic pole core, a magnetic field coil, an armature and a carbon brush. Working principle of power generation: when the diesel engine drives the generator armature to rotate. Due to the residual magnetism of the pole core of the generator, the armature coil cuts the magnetic field lines in the magnetic field. According to the principle of electromagnetic induction, the current is generated by the magnetic induction and the current is output through the carbon brush.

The alternator is mainly composed of multiple permanent magnets (called rotors) with alternating north and south poles made of magnetic materials and armature coils (called stators) made of silicon cast iron and wound with multiple series coils. Working principle of power generation: The rotor is driven by the diesel engine to cut the magnetic field lines axially. The alternating magnetic poles in the stator create alternating magnetic fields in the coil core. When the rotor rotates once, the direction and size of the magnetic flux change many times. due to the transformation of the magnetic field. Induced currents of varying magnitude and direction are generated in the coils and delivered by the stator coils.In order to protect the electrical equipment and maintain its normal operation, the current sent by the generator also needs to be adjusted and controlled by a regulator.

Principle: In short, the diesel generator drives the generator to run.

In the cylinder, the clean air filtered by the air filter is fully mixed with the high-pressure atomized diesel fuel injected from the fuel injector. Under the upward extrusion of the piston, the volume shrinks and the temperature rises rapidly, reaching the ignition point of diesel. When the diesel is ignited, the mixed gas burns violently, the volume expands rapidly, and the piston is pushed down, which is called ‘work’. Each cylinder performs work in a certain order. The thrust acting on the piston becomes the force that pushes the crankshaft through the connecting rod. This drives the crankshaft to rotate. Install the brushless synchronous alternator coaxial with the diesel generator crankshaft. The rotation of the diesel generator can be used to drive the rotor of the generator. Using the principle of ‘electromagnetic induction’, the generator will output an induced electromotive force. A current can be generated through a closed load circuit.

Only the most basic working principle of the generator set is described here. To get usable, stable power output. A range of diesel generators and generator controls, protection devices and circuits are also required.

Island mode of operation.

One or more diesel generators operating without being connected to the grid is referred to as an islanding mode of operation. Working generators in parallel can achieve better efficiency at part load. An island power plant for mains power in isolated communities will typically have at least three diesel generators. Any two of them are rated to carry the required load.

Generators can be linked together through a synchronization process. Synchronization involves matching voltage, frequency and phase before connecting generators to the system. Failure to synchronize prior to connection may result in high short-circuit currents or wear on the generator or its switchgear. The synchronization process can be done automatically by the automatic synchronization module, or manually by a guided operator. The automatic synchronizer will read the voltage, frequency and phase parameters from the generator and bus voltage. At the same time the speed is regulated by the engine governor or ECM (Engine Control Module).

The load can be shared between generators running in parallel through load sharing. Load sharing can be achieved by using droop speed control controlled by generator frequency. At the same time it constantly adjusts the engine fuel control to transfer load to or from the remaining power source. Diesel generators will take on more load when the fuel supply to their combustion system increases. And if the fuel supply decreases, the load is released.

Diesel generator set composition:

The packaged combination of diesel engine, generator and various auxiliary devices such as base, top cover, sound attenuation, control system, circuit breaker, jacketed water heater and starting system is called a “generator set”.

1. Standard unit

Standard units are widely used in general installations in computer rooms. The unit is mainly composed of diesel engine, generator, control system, frame, shock absorber, cooling system, oil supply system, and output protection switch.

2. Protective unit

Protective units are used in outdoor places where there are no special requirements for noise. It is mainly composed of standard unit, protective cover, smoke exhaust system, etc. Since the protective cover is not provided with a noise reduction device, it only needs to meet the conditions of ventilation and rain and snow protection. Therefore, its external volume is small and the cost is low. Open doors and windows for ventilation when the unit is running. The protective power station can be used alone or in parallel. The parallel use of multiple units is especially suitable for occasions with large load changes, high requirements for continuous operation reliability and low-cost economical use. Such as supporting oil field drilling rigs, etc.

3. Soundproof unit

Soundproof units are widely used in outdoor or indoor places with special requirements for environmental protection where protection and noise reduction are required. It is mainly composed of standard unit, soundproof cover, air inlet and exhaust noise reduction device and exhaust noise reduction device. Its main features are that the soundproof cover is provided with sound insulation and sound absorption layers, the air inlet and exhaust channels are noise-reduced, and the exhaust adopts a combination of industrial and residential mufflers. Reduce its high-frequency and low-frequency noise, respectively. The noise of standard soundproof units is generally 78 to 85dB (A). The noise of the super soundproof type unit is generally 70 ~ 78dB (A). The super soundproof unit adopts stricter control measures on noise emission based on the standard soundproof unit. Such as the use of labyrinth air inlet and exhaust channel design, etc. to achieve.

Super sound-proof units generally have larger dimensions. Manufacturing costs are also much higher than standard soundproof units. Soundproof units and super soundproof units are usually operated, maintained and serviced outside the soundproof enclosure.

4. Open-air power station

Low-noise shelter power stations and container power stations are generally used in outdoor places with special requirements for environmental protection. It can be directly placed outdoors and used in the open air, eliminating the need to build a computer room. At the same time, it has the characteristics of strong mobility and short service cycle. The noise of low-noise shelter power station and container power station is generally 75-85dB (A), which can be operated, maintained and overhauled in the shelter and cabin.

5. Vehicle mobile power station

Vehicle-mounted power stations are widely used in communications, television broadcasting, highways, emergency rescue, power supply, and the military. For power emergency occasions that require high speed, mobility and reliability. The unit is mainly installed in the cabin of the car. And can be equipped with electric cable winches, multiple output sockets and mechanical (or hydraulic) outriggers. It is also very convenient to realize the parallel use of multiple vehicle-mounted mobile power stations. The general noise of vehicle-mounted mobile power station is 70-80dB (A).

6. Unit size

For homes, small shops and offices, device sizes range from 8 to 30 kW (also 8 to 30 kVA single phase).

For factory,  large industrial generators from 8 kW (11 kVA) to 2,000 kW (2,500 kVA three-phase) complexes. The 2,000 kW unit can be installed in a 12-meter ISO container, with fuel tanks, controllers, power distribution equipment and all other equipment required to operate as a stand-alone power station or as a backup for grid power.

Combinations of these modules are used in small power stations. And each module uses 1 to 20 units and can be combined into hundreds of power modules. In these larger sizes, the power modules (engine and generator) are brought to the trailer individually. And connected together with large cables and control cables to form a fully synchronized power plant. There are also many options to meet specific needs, including control panels for automatic starting and power paralleling, ventilation for stationary or mobile applications, fuel supply systems, exhaust systems, and more.

Power supply for daily use

Although the power of diesel generator sets is lower. However, due to its small size, flexibility, lightness and complete supporting facilities, it is easy to operate and maintain. Therefore, it is widely used in mines, railways, field construction sites, road traffic maintenance, as well as factories, enterprises, hospitals and other departments.

Emergency Power Supply

Diesel generator sets are used where they are not connected to the grid, or as an emergency power source in the event of grid failure, as well as for more complex applications such as peak tripping, grid support and grid output.

Direction of development

The generator set shoulders the important task of providing complete sets of power generation equipment for the national economy and people’s living electricity. So it will still occupy a very important position for a long time. And with the progress of the times, the development of society. The original type of generator set is cumbersome, high in fuel consumption, loud in noise, and serious in exhaust gas pollution, which is obviously not suitable for the needs of society. Therefore, the development direction of the generator set in the future should be energy saving, environmental protection, light weight, miniaturization and beautiful appearance. Only in this way can the potential advantages of the generator set be brought into play.

Our ITCPOWER is a factory dedicated to this development. We have a wealth of experience and my mature technology sector. In the near future, this can be achieved.