Selection of emergency diesel generator
Generally, the emergency diesel generating set with high speed, supercharging, low fuel consumption and the same capacity should be selected. The high-speed turbocharged diesel engine has large capacity and small space; the diesel engine is equipped with electronic or hydraulic speed control device, which has good speed regulation performance; the synchronous motor with brushless excitation or phase compound excitation device should be selected for the generator, which is more reliable, with low failure rate and convenient maintenance and repair; when the capacity of single air conditioner or motor in the first level load is large, the third harmonic excitation should be selected In order to reduce the impact of noise on the surrounding environment, a muffler should be installed at the outlet of the exhaust pipe. (1) Determination of capacity: the emergency diesel generator set should be in emergency operation, often in standby emergency start state, the continuous operation time is not long, generally not more than 8h, so the capacity can be determined according to the "standby power". According to the sum of the capacity of the first level load (excluding the reserve capacity), considering the revised unit capacity and meeting the starting requirements of a large motor in the first level load, the capacity of the emergency diesel generator set is determined. Generally, three-phase AC synchronous generator is selected as emergency generator, and its rated output voltage is 400V. (2) Determination of the number of units: generally, one generator set with automation, speed of 1000-1500 rpm, brushless excitation, 400 / 230V, three-phase four wire with control panel, charging and discharging equipment and common chassis is selected. Common chassis with daily fuel tank can be required to reduce pipeline and occupied area. In addition, considering the reliability, two units in parallel can be selected for power supply. Generally, the number of emergency generating units should not exceed 3. When multiple units are selected, complete sets of equipment with the same model and capacity, similar pressure regulation and speed regulation characteristics shall be selected as far as possible, and the fuel used shall be consistent, so as to facilitate maintenance and share spare parts.
Selection of standby diesel generator set
When the calculated load of the sum of load capacity multiplied by the demand factor is less than the capacity of emergency diesel generator set, the standby factor is considered as 1.2, that is, 1.2 times of the calculated capacity is less than the capacity of the emergency diesel generator set, and the emergency generator set will supply power to the load after the mains power outage. When the calculated load of the sum of load capacity multiplied by the demand factor is greater than the capacity of a single emergency diesel generator set, two automatic generator sets with the same model, capacity, similar voltage regulation and speed regulation characteristics can be selected. After the power failure, one or two units will supply power to the domestic and commercial power; when the power is cut off and there is a fire, the two units will supply power to the fire fighting load to facilitate the fire fighting.
Reasonable selection of generator set
There are many kinds of generator sets in the market, such as gas turbine generator set, diesel generator set, hydraulic generator set and wind turbine generator set. Different types of generator set have different performance, application range and market situation. Therefore, reasonable selection of generator set is necessary. Gas generator set is usually used for normal load. The fuel used is natural gas, which has the advantages of wide output power range, high reliability of start-up and operation, good power generation quality, small volume and light weight, simple maintenance, low-frequency noise, low cost, and conducive to environmental protection. However, natural gas needs to be obtained locally, but there is no large-scale distribution of natural gas energy in China The scope is affected. In addition, there are potential safety hazards for users who are not professional. Diesel generator sets are usually used as emergency or standby power supply, and the fuel used is diesel, which is a non renewable resource with relatively high cost. However, the purchase and storage of diesel oil is more convenient than that of natural gas, with large single unit capacity, wide range of use, high thermal efficiency, low fuel consumption, rapid start-up and mature maintenance technology. Therefore, more diesel generator sets are selected in the general market. Hydroelectric generating units are generally used in various hydropower stations, with the characteristics of low cost, small volume, light weight, simple structure, reliable operation, convenient installation and use, which is suitable for mountainous households in water resources to solve the power generation equipment of lighting, television and other power consumption, but it needs rich water resources conditions. Wind turbine uses natural energy, pollution-free, renewable energy, better than diesel power generation, but as an emergency, it is not as good as diesel generator. Wind turbine can not be regarded as standby power, but it can be used for a long time. It is generally suitable for areas far away from the power grid, pastoral areas, mountainous areas, islands and other areas with abundant wind resources. In addition, there is still a big gap between cost and technology and traditional thermal power and hydropower, simultaneous interpreting, and the support of national policies. Therefore, generally, diesel generator set should be selected as power generation equipment in engineering.