The Transformation Research On Deficient Load-Break Rating Of Generator Circuit-Breaker

With the continuous operation of large capacity units,energy base continue to emerge,the power capacity is more and more big,the grid structure is more complex,in order to ensure the safety and reliability of power grid operation,the development of relay protection system is also more and more powerful,manufacturing execution level of circuit breaker closing function has been greatly improved.To ensure the total energy supply foundation to meet the needs of economic development,in order to reduce the environmental pressure and optimize the energy consumption structure,China will proceed with one million kilowatts of nuclear power units and one million kilowatts of ultra supercritical thermal power planning and construction work from the last century since the end of 90s.In order to ensure the stable operation of million kilowatt unit operation safety and power system,generator set generator circuit breaker(GCB)to form a unit,to improve the safety of the unit operation,and reduce the influence on the stability of the power grid caused by fault.The breaker manufacturing process technology development is slow,the circuit breaker load-break rating has not been effectively promoted in a very long period of time.With the increase of power grid capacity,energy base in large capacity generating units have been put into production,power system short circuit capacity also increase,the need for protection of the original design value check again,when necessary to adjust the mode of the system operation,in order to ensure the correct operation of relay protection system,to protect the equipment to reduce accidents the consequences.In this paper,a nuclear power plant in China began construction in 90s as an example,the nuclear power plant currently has two sets of power generation by millions of nuclear power units and four units in the construction period of the millions of nuclear power plants,and four sets of construction period will have been put into power generation in the next 4-5 years.This will have an adverse impact on the value of the relay protection in power system,especially may lead to flow through the generator circuit breaker(GCB)short-circuit current increases.Therefore,firstly this paper makes a comparative analysis of three methods to calculate the short-circuit of the system,then choose value per unit in this paper.In the current two units running and the next four units running these two maximum operating modes,in view of the possible short-circuit situation in the factory,calculation of short circuit current flowing through the generator outlet circuit breaker(GCB),analysis the safety of the current power plant operation and the potential risk of future power plant operation.Combined with the treatment of generator circuit breaker(GCB)load-break rating insufficient practice in current,discuss the most economical and feasible optimization measures to solve the problem,and aiming at the project construction of power plant and the plan of grid connecting and transportation,and take the form of project plan,formulate measures for the implementation of the time node,to ensure the safety and economic operation of the power plant and the safety and stability of the power grid.