Working principle of diesel generator

Diesel Generator

Basic Information

A generator driven by an internal combustion engine. It starts quickly and is easy to operate. However, the cost of generating electricity from internal combustion engines is high, so diesel generators are mainly used as emergency backup power sources, or used in mobile power stations and areas where large power grids have not yet reached. The speed of diesel generators is usually below 1,000 rpm, and the capacity ranges from a few kilowatts to several thousand kilowatts, especially units below 200 kilowatts are widely used. It is relatively simple to manufacture. The torque output on the diesel engine shaft pulsates periodically, so the generator works under severe vibration conditions. Therefore, the structural components of the diesel generator, especially the rotating shaft, must have sufficient strength and rigidity to prevent these components from breaking due to vibration. In addition, in order to prevent uneven rotation angular speed of the generator due to torque pulsation, resulting in voltage fluctuations and light flickering, the rotor of the diesel generator is also required to have a large moment of inertia, and the natural torsional vibration frequency of the shaft system should be consistent with the The frequency of any alternating component in the torque pulsation of the diesel engine differs by more than 20% to avoid vibration and shaft breakage accidents.

Diesel generator set

Mainly consists of a diesel engine, a generator and a control system. There are two ways to connect the diesel engine and the generator. One is a flexible connection, that is, a coupling is used to connect the two. The second part is butted together, and the second part is a rigid connection, which uses high-strength bolts to connect the steel connecting piece of the generator and the diesel engine flywheel disk. Currently, more rigid connections are used. After the diesel engine and generator are connected, they are installed at the bottom of the park. on the rack, and then equipped with various sensors, such as water temperature sensors. Through these sensors, the operating status of the diesel engine is displayed to the operator. With these sensors, an upper limit can be set, and when the limit value is reached or exceeded, the control The system will alarm in advance. If the operator fails to take measures at this time, the control system will automatically stop the unit. This is how the diesel generator set protects itself. Sensors play the role of receiving and feeding back various information. What actually displays these data and performs protection functions is the control system of the unit itself.

Diesel generator model meaning

The diesel generator set is a power supply device that uses a diesel engine as power to drive a synchronous alternator to generate electricity. In order to facilitate production management and use, the state has unified regulations on the name and model compilation method of diesel generator sets. The model arrangement and symbol meanings of the units are as follows: 1

2

3

4

5 ---- 6

7

The model of the diesel generator set. The symbols and numbers represent the models as follows: 1---Output rated power (KW), expressed in numbers. 2---Output voltage type G represents AC power frequency; P represents AC intermediate frequency; S represents AC dual frequency; Z represents DC. 3---Generator set type; F represents land use; FC represents marine use; Q represents automobile use; T represents trailer use. 4---Control characteristics, the missing unit is a manual (ordinary) unit; Z represents an automated unit; S represents a low-noise unit; SZ represents a low-noise automated unit. 5---Design serial number, represented by numbers. 6---Variant code, represented by numbers. 7---Environmental characteristics, absent ordinary type; TH represents hot and humid type.

Examples of the meaning of diesel generator sets

(5) 120GFSZ1 represents an automated diesel generator set with an output rated power of 120KW, AC power frequency, land use, low noise, and design serial number 1 . (6) 200GFC1 represents a diesel generator set with an output rated power of 200KW, AC power frequency, marine use, and a design serial number of 1. (7) 120GT6 represents a diesel generator set with an output rating of 120KW, AC power frequency, trailer type (i.e. trailer type), design serial number 1, and design serial number 6. (8) 90GQ1 represents a diesel generator set with an output rating of 90KW, AC power frequency, automotive type, and design serial number 1.

(9) 17ZQ1 represents a diesel generator set with an output rating of 17KW, DC, automotive type, and design serial number 1. Some domestic diesel generator series models are determined by the unit manufacturer themselves, which have different meanings from the above models.

Principle of Diesel Generator

The diesel engine drives the generator to operate, converting the energy of diesel into electrical energy. In the diesel engine cylinder, the clean air filtered by the air filter is fully mixed with the high-pressure atomized diesel fuel injected from the injector. Under the upward squeeze of the piston, the volume shrinks and the temperature rises rapidly, reaching the ignition point of the diesel fuel. The diesel is ignited, the mixed gas burns violently, expands rapidly in volume, and pushes the piston downward, which is called 'work'. Each cylinder performs work in a certain order, and the thrust acting on the piston becomes the force to push the crankshaft to rotate through the connecting rod, thus driving the crankshaft to rotate. By installing the brushless synchronous alternator coaxially with the crankshaft of the diesel engine, the rotation of the diesel engine can be used to drive the rotor of the generator. Using the principle of 'electromagnetic induction', the generator will output an induced electromotive force, and a current can be generated through the closed load loop. . Only the most basic working principle of the generator set is described here. In order to obtain usable and stable power output, a series of diesel engine and generator control, protection devices and circuits are also required. Diesel generator set is an independent power generation equipment, which refers to a power machine that uses diesel as fuel and a diesel engine as the prime mover to drive a generator to generate electricity. The entire unit generally consists of a diesel engine, generator, control box, fuel tank, battery for starting and control, protection device, emergency cabinet and other components. The whole unit can be fixed on the foundation for positioning use, or it can be mounted on a trailer for mobile use. Diesel generator sets are non-continuous operation power generation equipment. If they run continuously for more than 12 hours, their output power will be about 90% lower than the rated power. Although the power of diesel generator sets is low, due to their small size, flexibility, lightness, complete facilities, and easy operation and maintenance, they are widely used in mining, railways, field construction sites, road traffic maintenance, as well as factories, enterprises, hospitals and other departments , as a backup power source or temporary power source. At the same time, this small generator set can also be used as a small mobile power station and has become a backup power supply for many enterprises.