Selection Of Generating Sets Capacity

In the planning specification of power supply and distribution system, power load is divided into one, two and three levels. At the same time, the main load needs to be powered by two power sources; In particular, the important load in the first load needs two power supplies, and also needs emergency power supplies, which are mandatory Settings of emergency power supplies. In addition, the backup power supply is set up for economic and political reasons to prevent the loss of data and information due to the loss of normal power supply or the adverse effects of political image. Based on the above, diesel generator sets are used as emergency backup power in many projects. The following is a brief introduction to some related content of building electrical planning in the planning of diesel generator sets.

1.Location of A diesel generator room.

Diesel generator room should be generally located in the power load center, to prevent cable investment due to the length of the line, increase investment to ensure the quality of power supply voltage. In the working process of diesel generator set, the location of diesel generator room should also consider many factors: on the one hand, to ensure the working environment of the unit itself, that is, ventilation, exhaust and smoke exhaust in the working process of the unit. Only diesel fuel is considered here. Since most projects on the market now use diesel as fuel, fuel supply and storage is also an important factor to consider in the machine room setup. Diesel generator set in the process of working, because the combustion of diesel will produce a lot of smoke, diesel generator set will produce gas and heat when working. These smoke, gas, heat not only adverse to the work of the diesel generator set itself, but also cause environmental pollution to people's activities. Therefore, when choosing the direction of the diesel engine room, it should be taken into account that the flue gas, gas and heat can be well discharged away from the indoor and personnel entrance and exit, and fresh air can be introduced into the engine room together to form a good heat dissipation and ventilation environment. On the other hand, the diesel generator set will vibrate and produce noise at work, which requires that the impact of vibration and noise on the environment should be considered when selecting the engine room location, and reasonable vibration and noise reduction methods should be taken when necessary. To sum up, the above requirements are considered. If general conditions permit, the diesel engine room can be located outdoors near the project, deviating from the revenue and expenditure VI and densely populated. When conditions do not allow, many projects are now at the bottom. After effective ventilation, ventilation, smoke exhaust, vibration reduction and noise reduction, they have also done excellent work and achieved good economic benefits.

2 .diesel generator set capacity selection.

Generally in the planning or early planning stage, we have no way to know the detailed load situation. At this time, the capacity of the diesel generator set is considered to be 10% ~ 20% of the total capacity of the distribution transformer, as described in the manual and professional technical methods. In the construction drawing planning stage, when we identify the required capacity of the diesel generator set, we should first identify the load type of the diesel generator set and the situation of using the diesel generator set, that is, the diesel generator set is used as a pure standby load, but still needs normal load. Diesel generators are also used as a power source for normal loads when the mains are out of power. The standby load mentioned earlier here refers to the load for which standby power is required among all necessary requirements because of fire fighting requirements and power supply assurance requirements. Power supply load identification is a reasonable scheme considering power supply reliability, economy and other factors. Only when the power supply load of the project is recognized can the capacity of the diesel generator set be further recognized. Please refer to JGJ 16-2008 Code for Electrical Planning of Civil Buildings for the calculation formula of diesel generator set capacity, which will not be used here.

3.Planning of diesel generator set and power supply and distribution system.

According to the number of diesel generator set, the nature of load, function and power supply requirements, there are many power supply systems choose diesel generator set as backup power supply. At present, the typical power supply system commonly used in practical application includes :(1) the generator set directly supplies power to the general load; Multiple generator sets are connected in parallel to supply power for general loads; Single machine as backup power supply and power supply to load; A plurality of units and a plurality of transfer switches respectively supply power to the load; 4F is the distribution system of medium and high voltage short-time generator in ordinary power supply. Multiple generators and commercial power sources are selected as medium and high voltage systems to supply power to loads through busbar connection or parallel connection. Low voltage generators use boost transformers to supply power to low or medium voltage distribution systems. Select a power supply mode based on the local power grid and actual load operation. At the same time, a single unit as backup power supply and mains power supply to load respectively, multiple units and switches respectively to load power supply, is a commonly used low-voltage power supply and distribution system in many projects. When the recognized diesel generator set capacity is large, generally not less than 800 kW, two diesel generators of the same capacity should be installed, which can bear part of the load respectively or can be used in parallel to supply power to all loads. Two diesel generator sets together can also be used for each other. When one is defective or requires regular maintenance, the other can be used as a backup power source for some of the highest demand or mandatory guaranteed loads. Diesel generators are generally not allowed to run alongside the city grid. The main consideration is that if the diesel generator set has shortcomings, it may involve the market network, and then expand the impact of shortcomings. So the chain generally choose diesel engine and electricity, to prevent them from working side by side. The starting method and requirements of diesel generator set should also be determined according to the nature of the load and the power supply scheme. Unit control cabinet is generally supplied by the manufacturer in complete sets. Because diesel generator sets generally rely on electricity to start, starting equipment such as chargers, batteries, etc., need all necessary mains power supply, so diesel generator room also need to set up mains power supply. When the diesel generator set is used as an emergency backup, when the normal power supply, namely the mains power failure, when the mains power - diesel generator set conversion control system announces the signal to start the diesel generator set; When the mains is restored, the control system announces a signal to stop the diesel generator set and restore normal mains supply. Whether PLC control or centralized control unit control, generally require overload, short circuit protection and other protection functions. When the capacity of the diesel generator set is insufficient, the unnecessary load can be unloaded, and the unloaded load can be resumed after the power supply is restored to normal.

4.Diesel generator cooling system planning.

At present, the cooling methods of diesel generator set on the market are divided into air cooling and water cooling. Air cooling is also called closed self circulation water cooling. The specific choice of cooling mode is generally recognized by HVAC professional according to site conditions and unit coordination. The choice of cooling method may also affect the orientation, size and layout of the diesel generator house. Besides the cooling system, ventilation is also important. About 20% of the heat generated by fuel combustion in the diesel engine cabin is emitted by the coolant system, 30% by exhaust gas, 3%-8% by the communication generator, 5% by the unit itself to the engine room, and at most 36% as electrical energy output. According to the above different forms of heat, the corresponding method is selected to exclude it from the diesel engine room, so as to ensure the normal working temperature of starter.

Guangxi Dingbo Power Equipment Manufacturing Co., Ltd. established in 2006, is an manufacturer of diesel generator in China, which integrates design, supply, commissioning and maintenance of diesel generator set. Product covers Cummins, Perkins, Volvo, Yuchai, Shangchai, Deutz, Ricardo, MTU, Weichai etc. with power range 20kw-3000kw, and become their OEM factory and technology center.