Design On Secondary Loop Detection For Relay Protecting System Of Integrated Automation Substations

Substation integrated automation technology is developing direction of power system. With the expansion of power systems and applications of digital equipment,the task of the substation maintenance,installation and commissioning for the secondary circuit of relay protection is becoming more and more heavy,especially after the constructions of new substations,installation of new equipment.The secondary loop is not only doing a great job of serving the measuring and controlling of power system,but playing a very important role in relay protection as well. The research of the secondary circuit of the relay protection and state detection technology, and applications of practical power system is of great significance.This thesis summarizes the present AC loop testing substations,Pointing out their theories and defects,and proposes a brand new testing method of AC loop.This method would help detecting the secondary AC loop.lt can be used for the text of CT,PT and checking polarities as well.In order to process the difficulties of measuring weak current and voltage signals,the thesis investigates the advanced weak signal detection and digital signal processing techniques based on DSP.In order to suppress electronic devices and circuits the mechanism and characteristic of shot noise in macroscopic electronic devices should be researched,low-noise level devices and circuits will be obtained, and proposes the scheme of measuring the AC weak signal of power systems.Finally,the paper proposes a detector which is able to measure weak current and voltage signals,and is capable of cheeking the secondary loop in substations.The application of innovation and instrument will improve the ability of testing AC loop,this method can guarantee the quality of power supply and the reliable operation of the power system,and it has the potential to be widely applied in the future.