What Is a Generator Set?

The generator set quickly increased in temperature when the volume of the diesel generator set was reduced, reaching the ignition point of the diesel. Diesel is ignited, the mixed gas burns violently, and the volume expands rapidly, pushing the piston downward, which is called 'work'.

Coal-fired generators are mechanical equipment that converts the chemical energy of fossil fuels such as coal into electrical energy. The working principle of coal-fired generating units is to convert the thermal energy generated by the combustion of coal into electrical energy through power generating units (power plant boilers, steam turbines and generators and their auxiliary devices, etc.). Coal-fired power generation has a long history and is also a more important one.

Coal-fired generating units are mainly composed of combustion systems (with boilers as the core), soda-water systems (mainly composed of various pumps, feed water heaters, condensers, pipes, water-cooled walls, etc.), and electrical systems (with turbo-generators, Transformers, etc.), control systems and other components. The first two generate high-temperature and high-pressure steam; the electrical system realizes the transformation from thermal energy, mechanical energy to electrical energy; and the control system guarantees the safe, reasonable and economical operation of each system. Coal-fired power generation, as a traditional power generation method, also has its disadvantages and deficiencies. For example, the continuous growth of acid gases such as SO2 and NOX emitted from direct combustion of coal has increased the amount of acid rain in China, and dust pollution has affected people's lives and plants Adverse effects on growth. Therefore, it is necessary to continuously improve the schedule of coal-fired power generation, use various technologies to improve power generation efficiency, and reduce environmental pollution, such as desulfurization and dust removal for flue dust or natural gas, and gas turbines use air cooling.

Generator selection factors

1. Reasonable selection of generator sets.
There are gas generator sets, diesel generator sets, hydraulic generator sets and wind generator sets on the market. Different types of generator sets have different performance, range of use, market conditions, etc., and should be selected reasonably. Gas generating sets are generally used for normal load. The fuel used is natural gas, which has a wide output power range, high starting and operating reliability, good power generation quality, small size and light weight, simple maintenance, low frequency noise, and low cost. Low, good for environmental protection and other advantages, but natural gas needs to be obtained on-site, and there is no large-scale distribution of natural gas energy in China, and the scope of supply is affected. In addition, there are security risks for less professional users. Diesel units are usually used as emergency or backup power. The fuel used is diesel, which is a non-renewable resource and expensive. However, diesel is more convenient to purchase and save than natural gas, has a large single-unit capacity, wide range of use, high thermal efficiency, and low fuel consumption Quick start-up and mature maintenance technology, so diesel generator sets are the most commonly used on the market. Hydrogen generators are generally used in various hydropower stations. They have the characteristics of low cost, small size, light weight, simple structure, reliable operation, and convenient installation and use. They are suitable for farmers in mountainous areas with hydropower resources to solve power generation equipment such as lighting and televisions. , But need to have abundant water resources. Wind turbines use natural energy, pollution-free and renewable energy, which is much better than diesel power, but it is not as good as a diesel generator for emergency use. Wind turbines are not considered backup power, but they can be used for a long time. Generally suitable for use in areas far from the power grid, pastoral areas, mountain areas, and islands with abundant wind resources. In addition, whether it is cost or technology compared with traditional thermal power and hydropower, there is still a large gap, and it also needs the support of national policies. Therefore, it is generally appropriate to use diesel generators as power generation equipment in engineering.
2. Several factors should be considered when selecting a unit.
It mainly includes mechanical and electrical performance, the use of the unit, the capacity and change range of the load, the use of the unit's environmental conditions (including altitude, climatic conditions, noise), automation functions, and so on. Because diesel generator sets can be used in three situations: common, standby and emergency, the requirements for diesel generator sets are different for different uses.
3. Selection of common generator sets.
Common generator sets have a long continuous working time, a large change in load curve, and the choice of unit capacity, number, type, and control method of the unit are different from emergency units. (1) Determination of capacity: According to the long-term continuous operation, the output power can meet the maximum calculation load selection of the entire project, and the capacity of the standby unit of the generator set should be determined according to the importance of the load. The continuous output power of a diesel engine is generally 0.9 times the nominal power. (2) Determination of the number of units: Generally, there are usually more than two units to ensure the continuity of power supply and adapt to the change of the load curve. Only a large number of units can determine the number of generators to be put into operation based on changes in the power load, so that diesel engines often operate under economic loads to reduce fuel consumption and reduce power generation costs. The best economic operating state of a diesel engine is between 75% -90% of the rated power. In order to ensure the continuity of power supply, the common unit itself should consider setting up a standby unit. (3) Determination of rotation speed: In general, high speed units with a rotation speed of 1000 to 1500 rpm should be selected for general civilian use, and low speed units with a rotation speed of 300 to 350 rpm are suitable for use as marine main engines. (4) Determination of voltage: The determination of the output voltage of the generator is the same as that of the emergency generator set, which is generally 400V. Individual projects with large power consumption and long transmission distances can choose high-voltage generator sets.
4. Selection of standby generator set.
The sum of the load capacity, when the calculated load after multiplying by the required coefficient is less than the capacity of the emergency diesel generating set, the reserve factor is considered according to 1.2, that is, 1.2 times the calculated capacity is less than the capacity of the emergency diesel generating set. The unit supplies power to the load. When the sum of the load capacity and the calculated load after multiplying the required coefficient is greater than the capacity of a single emergency diesel generator set, two automatic generator sets with the same model, the same capacity, and similar voltage and speed characteristics can be selected. After the mains power failure, one or two units supply power to domestic and commercial power; when the mains power fails and a fire occurs, the two units supply power to the fire-fighting load to facilitate fire protection.
5. Selection of emergency generator.
Emergency generators are generally suitable for high-speed, supercharged, low fuel consumption, and same-capacity generator sets. High-speed turbocharged diesel engines have a large single-unit capacity and occupy a small space; diesel engines are equipped with electronic or hydraulic speed regulators for better speed regulation performance; generators should use synchronous motors with brushless excitation or phase compound excitation devices for reliable and faulty operation The rate is low, and maintenance is convenient; when the capacity of a single air conditioner or the motor is large in the first-level load, a third-harmonic excitation generator set should be selected; the machine is assembled on a common chassis with shock absorbers; exhaust smoke Mufflers should be installed at the pipe outlet to reduce the impact of noise on the surrounding environment. (1) Determination of capacity: The emergency generator set is used for emergency purposes, and is often in the standby emergency starting state. The continuous operation time is not long, generally not more than 8 hours, so the capacity can be determined according to "spare power". According to the sum of the capacity of the first-stage load (excluding reserve capacity), the revised unit capacity is considered, and the starting requirement of the largest motor in the first-stage load can be met, and the capacity of the emergency diesel generator set is determined accordingly. Emergency generators generally use three-phase AC synchronous generators with a nominal output voltage of 400V. (2) Determination of the number of units: Generally, one generator set with automation, speed 1000-1500 rpm, brushless excitation, 400 / 230V, three-phase four-wire with control screen, charging and discharging equipment and shared chassis is selected. A common chassis with a daily fuel tank can be required to reduce piping and footprint. In addition, from the perspective of reliability, two units can also be selected for power supply in parallel. Generally, the number of generator sets for emergency use should not exceed three. When multiple units are selected, the units should try to use complete sets of equipment with the same model and capacity, similar pressure and speed characteristics, and the fuel properties used should be the same for maintenance and shared spare parts.
6. Selection of the starting mode of the unit.
There are three ways to start a diesel engine: crank start; electric start; compressed air start. In high-rise buildings, electric starting should be adopted instead of compressed air. In a class of high-rise buildings, a diesel generator set with a self-starting device must be selected. Once the mains power supply is interrupted, power must be supplied within 15 seconds (higher requirements require 30 seconds). Units with self-starting devices should also be used when conditions are available in Class II high-rise buildings, and manual starting devices can also be used when difficult.
7, performance and quality must meet the requirements of relevant standards.
As a communication diesel generator set, it must meet the requirements of G3 or G4 level in GB2820-1997 and the 24 performance index requirements stipulated in the Implementation Rules for the Quality Inspection and Certification of Communication Diesel Generating Units. At the same time, it must pass the communication power supply. Strict inspection by equipment quality supervision and inspection center. As a military communications diesel generator set, it must meet the relevant GB2820-1997, GJB related standards and the "Quality Test Standards for Communication Power Equipment" formulated by the relevant departments of the army, and must pass strict inspections of equipment quality by relevant organizational departments.
8. Matters needing attention when matching with three-phase motors.
When selecting the capacity of the generator set and the three-phase motor, it is recommended to consider a safety factor of 1.5, which is 1.5 times the motor capacity (must be a soft-start method).
9. Pay attention to the relationship between rated power and backup power, and the relationship between KVA and KW.
Some manufacturers in the market only say one "power" and introduce the backup power as the rated power to introduce and sell the unit. Actual backup power = 1.1x rated power. And the backup power can only be used for 1 hour in 12 hours of continuous operation. Diesel generator sets are generally identified with rated power in China, while standby power is used internationally. KVA is the apparent power and KW is the effective power. The relationship between them is IKVA = 0.8KW. Imported units generally use KVA to represent power units, while domestic electrical equipment is generally represented by KW.
10. Identify the brand of the unit.
Generally, imported generator sets are assembled machines, but for domestically produced units, there are integrated units (that is, the generator and engine are of the same brand). Although the volume is larger than the imported ones, their performance is also different from some imported units. It is divided up and down, and the price is cheap, so you should fully understand the manufacturer and brand of the unit s diesel engine, generator, and control cabinet when purchasing (because some manufacturers only report the diesel engine or generator brand, do not report the origin, do not report the unit brand, etc. ) In order to comprehensively evaluate the rank of the crew.

Product introduction of generator set

Generator set refers to the power generation equipment that can convert mechanical energy or other renewable energy sources into electrical energy. In general, our common generator sets are usually driven by steam turbines, hydraulic turbines or internal combustion engines (gasoline engines, diesel engines and other engines). Renewable new energy sources include nuclear energy, wind energy, solar energy, biomass energy, ocean energy, etc. Due to the large capacity of the diesel generator set, it can be operated in parallel and has a long continuous power supply time. It can also operate independently. It does not run side by side with the regional power grid, and is not affected by grid faults. It has high reliability. Especially in the case that the common commercial power in some areas is not very reliable, using a diesel generator set as a backup power source can not only serve as an emergency power source, but also rationally optimize the low-voltage system to put some of the more important loads in power outages at power outages. It is widely used in engineering.

Fuel consumption of generator set

Many customers will consider the fuel consumption when choosing a generator set. Many users will not know the numbers marked on the parameters before selecting it. Like a 5KW gasoline generator set, its fuel consumption will be marked. 540g / KW / h means 540g per KW of fuel consumption. Many customers will think that this generator is 540g for one hour. In fact, this is not the case, it is 540g 1KW for one hour, which means that when this machine is fully loaded, it is 1 kilowatt, 540g, 5 kilowatts, or 5 540g. Of course, many customers will feel that the generator consumes too much fuel, but what I just said is that it is calculated under full load. So the actual fuel consumption cannot reach this much, because the generator and equipment will have a starting current, so generally speaking, buying a 5 kW gasoline generator will not use all 5 kW, and if your If the power of the equipment is not large, the power consumed by the generator is only 1/3.

Therefore, if the fuel consumption of the generator set is one, you don't need to pay much attention to it.

National production of generator sets

In 2011, China's generator and generator set manufacturing industry maintained rapid development. By the end of 2011, there were 704 manufacturers of generators and generator sets above the national scale, with a total industrial output value of 301.472 billion yuan; total assets of 315.831 billion yuan, a year-on-year increase of 27.07%; sales income of 290.69 billion yuan, a year-on-year increase of 19.54%; the total profit was completed 18.439 billion yuan, a year-on-year decrease of 10.06%.

Based on the historical data of the generator and generator set manufacturing industry from 2004 to 2011, analyze its data characteristics, calculate the annual average growth rate of the industry, and predict the total sales revenue and profit of the generator and generator set manufacturing industry in 2012. It is estimated that in 2012, the sales revenue of the generator and generator set manufacturing industry will exceed 400 billion yuan, and the total profit will exceed 25 billion yuan.

With the continuous expansion of the industry market scale, competition in the generator and generator set manufacturing industry will further intensify. Excellent domestic generator and generator set manufacturing companies have also paid more and more attention to the research of the industry market, especially the in-depth purchase of industrial buyers. the study. Because of this, a large number of excellent domestic generator and generator set manufacturers have risen rapidly and gradually become the leader in the generator and generator set manufacturing industry. ^[6]