Thermal Power Unit Plant With Power Supply's Research And Design Based On 2*300MW

The electric power enterprise is gradually changing from producting to operating model, along with the strengthening of national environmental protection and energy saving policy and the deepening and development of electricity market reform. To improve enterprise efficiency, reducing cost and enhancing enterprise core competitiveness could be the long-term goal of the electric power enterprise.Thermal power plant, which is the mainstay of electric power enterprises, is mainly responsible for human electric energy supply for the long term. Although new energy power generation development is swift and violent in recent years, the capacity for coal-fired power units is still at the top, which is closely connected with its inherent characteristics and functions of generating. The thermal power is reliable, stable, high safety, strong flexibility, and it supports the realization of the wind power and photovoltaic. Then the thermal power cannot be completely replaced by other power generation styles. Because of the widening of thermal power unit installed capacity and the maturing of new energy power generation technology, the thermal power unit utilization rate has fallen dramatically. In order to enhance market competitiveness and obtain more economic benefits, the thermal power enterprises need to be taken technical innovation and optimization of structural function.The main economic indices of coal-fired power units are power generation, power generation coal consumption, plant power consumption, ect. Because the thermal power unit system is complex and the high voltage auxiliary equipments are equipped with large capacity and large energy consumption, to optimize the auxiliary operation mode and improve the efficiency of the motor can reduce the plant power consumption and save the cost of production. Meanwhile, the start backup power supply equipments, which belong to power supply system of most 300 MW thermal power units, take power from high voltage grid in China. The standby transformer taking power form grid will cost a lot of off-grid electrical energy to supply factory load and its no-load loss. But the off-grid electricity price is higher than on-grid price. So reducing the amount of electricity taken form the grid can further reduce the cost of coal-fired power plants.This paper regards the #1,#2 300 MW coal-fired unit power supply system, which is belong to the Jingyuan second power Co., LTD of the SDIC, as the research object. Its auxiliary power supply system structure, principle of switching, and automatic transform system's working principle and control method are analysized. At the same time, two energy saving achievements of plant power supply system are acquied and shown as:(1) The high voltage frequency conversion technology is applied to improve the efficiency of the large capacity auxiliary equipment, reduce the energy consumption and save plant power consumption;(2) Using a single generator transformer allowance connect with the other units to replace the standby transformer connect with the grid, the standby transformer can be in a hot standby mode for a long time.According to the company second step, the power system energy saving plan(using the standby transformer in hot standby mode of power supply system to reduce power from grid) and the project of powered factory power supply system by the standby transformer in cold standby mode are analysized and designed, and they are applied in the plant power system successfully. The operation results show that the energy saving effect is obvious. Concretely, this design scheme remains all functions in original plan. And the factory power supply system is impoved by optimizing and improving the software system and the hardware circuit, such as: adopting new equipment(the inrush current limiter), effectively reducing the standby transformer no-load excitation inrush current. Mainwhile, the spare voltage transformer of the reliably powered factory power supply system is working in cold standby mode with the help of the automatic transform system, the no-load loss of standby power transformer is eliminated, and the consumption is reduced and the saving energy is achieved. In addition, the application of new technology innovation, adding a small delay in automatic transformer system logic, is used. Then the standby transformer could be charged before loading, and the protection misoperation is effectively prevented. Since the design is applied in the Jingyuan second power co., LTD., #1, #2 units, auxiliary power supply switchs are reliable, and the large amounts of eletricity from grid are saved. The design has won the colleagues' consistent approval and is worth spreading.