Design And Implementation Of Microcomputer Protection System In 35kV Cai Zha Substation

As the most widely used energy form in today's world,electricity plays an important role as one of the energy sources guaranteeing the safety of power system operation.To a certain extent,it can lead to the sustainable development of national economy.Power system failure caused by natural disaster or human factors,it will not only affect people's ordinary life,jeopardize the stability of power system,but may also may cause blackouts,bringing significant hurdle to the social economy.Therefore,strengthening microcomputer protection system in substation can have important theoretical and the practical significance for the power supply system,especially the safety,reliability and economic operation etc.In order to ensure the stability of power equipment operation and reduce the operation process of safety problems,it is necessary to conduct more in-depth research on relay protection,so as to fundamentally suppress large area blackout.The microcomputer protection system is an indispensable part of the second-order system of the modern power supply system,and it is a prerequisite for realizing the automatic industrialization of the substation.The relay protection design of the power system is stable and safety and has the function that cannot be ignored.It is an urgent work to ensure the safe and stable operation of the power grid.At present,due to the rapid technological evolution of China's industrial sector,the expansion of the power grid and increasingly complex architecture of the transmission network,the generation of the system has been increasing.The microcomputer relay protection device uses circuit breaker tripping and alarm signal to respond the abnormal operation of the power system and the protection equipment of the fault.Due to the booming development of the power system and the increase of voltage level,demand for microprocessor protection devices is also increasing.Therefore,we must further improve the microprocessor protection devices,to meet the requirements of the power industry operation.This paper was inspired by the reforming and upgrading project of Wuhan Cai Zha substation,during my practice period.First of all,the operation status of the existing substations is analyzed,combined with the requirements and expectations of the substation in the coming period.Then,the differential protection characteristics of the transformer are mainly studied,and the simulation model of differential protection algorithm is set up with the simulation software PSCAD/EMTDC,with the short circuit fault analyzed.Secondly,the overall design and calculation of the protective wiring of this station are carried out.In addition,this paper probes into the construction environment and source of interference source,also puts forward effective anti-interference measures.In the last part of the paper,according to the working mode and judgement basis of the second harmonic braking of differential protection,the correctness of the second harmonic braking coefficient selection is tested by the principle of the transformer's airdrop,so that the transformer is more reliable in the future.The system is now officially used in Chua squeezing substation and was put into operation in November 2017.The long-term operation,after the transformation of the substation run at good state,microprocessor-based protection operating stable and accurate,various indicators of microcomputer protection system for substation all reached the predetermined design requirements,and in the final of the future of the power substation is put forward and further intelligent development.