The unit of our factory is merged into the provincial network. Because the communication switch between the provincial network and our factory has many faults, it often trips. When the generator is under load, the unit often stops due to overspeed, which will cause the factory to be used seriously. Electrical interruption accidents are very unfavorable for the safe and continuous operation of power plants. In view of the fact that the 12 Turbine Generators of our factory have electric overspeed protection, the above faults have occurred due to unreasonable design. The author has made improvements to the electric overspeed protection system and achieved good results. 1 original system and its defects, the original system of our factory. Three generators run in parallel with the system through one main transformer, and another line of contacts can be used as a backup. Among them, the 1 and 2 generators are equipped with electric overspeed protection, but the wiring is complicated due to the two-way communication switch. When the system side switch fault trips, the electric overspeed protection cannot be operated. 2 Before the accident analysis and transformation, our factory repeatedly tripped due to the tie switch. When the generator and the system were juxtaposed, the steam turbine was seriously overspeeded, causing the overspeed protection action to stop, and the plant power interruption accident often occurred, resulting in serious shortage of water in the boiler and unable to resume production immediately. The role of the overspeed protection is not to cause a great loss to the production. 3 Improvement process and measures In order to ensure the safe and stable operation of our factory, we have made many improvements to the electric overspeed system, and finally achieved satisfactory results. After the contact switch is tripped after the transformation, the turbine is still running smoothly, which effectively prevents the impact of external impact on the safe operation of our plant. 3.1 Improvement of electrical wiring In 2000, due to the design of our factory, we did not consider that there are two communication lines in our factory. Only when the main change side switch (301 or 61A) trips, there is electric overspeed protection. In normal operation, the generator is placed in parallel with the system through the main transformer, and the protection can work. When the generator is operated by the standby switch (603) in parallel with the system or the standby switch (603) as a feeder, the protection does not play a protective role at all. In view of this situation, we have made changes to the protection circuit, and the auxiliary contacts of the standby switch are inserted into the electric overspeed protection circuit, which can change the above deficiencies and ensure the safety of the protection system in the factory. 3.2 Adding electric overspeed protection based on turbine speed Although the above improvement ensures the safety of the protection system in the plant, if the line side switch trips, the internal overspeed protection of the plant will not work at all, and the turbine overspeed protection will stop. In order to avoid such accidents, we analyzed the characteristics that the speed of the steam turbine will rise and the frequency of the power grid will be basically stable. The fluctuation of the turbine speed exceeding the grid frequency is considered to be the generator overload load protection. 4 Conclusion After the above transformation, after more than one year of use, we have repeatedly operated the electric overspeed protection in various generator load rejection accidents, ensuring the power consumption of the plant and bringing great benefits to our factory. 71994-2015ChinaAcademicournal Pearlescent Pigment Silver White Series Pearlescent Pigment Silver White,White Mica Powder,Silver White Pearl Pigment,Silver White Mica lilygroup Co.,Ltd , https://www.lilychemical.com
Improvement of 2×6MW Turbogenerator Electric Overspeed System