Operation And Maintenance Status Analysis And Safety State Assessment Of Subsation Main Grounding Grid In Jiangxi

Grounding is the basis to ensure the reliable operation of power system and personal safety.With the development of China's power grid to large capacity,the improvement of substation automation has brought electromagnetic problems more and more prominent.At the same time,it is more and more difficult to expropriate land for substations and outgoing corridors,and the grounding working conditions are becoming stricter and stricter due to the worse soil conditions.In this context,secondary equipment and micro-electronic equipment gradually improve the requirements of safety indicators such as grounding grid potential rise and field voltage difference.The stable operation of the power grid puts forward more and more stringent requirements for the safety and reliability of the grounding grid.Reasonable assessment of the safety status of grounding grid can avoid some accidents and provide guarantee for the safe and stable operation of power system.Firstly,the characteristic parameters of substation grounding grid are analyzed,and the function and safety of grounding grid are briefly introduced.The technical indexes and measurement methods of grounding resistance,step voltage,contact voltage,electrical integrity and soil resistivity are mainly introduced.The basic theory of grounding simulation is introduced,including electromagnetic field theory,layered soil resistivity model,equipotential grounding grid model,unequal grounding grid model and frequency domain model.It provides a basis for the calculation of grounding grid parameters.Secondly,through the analysis of grounding impedance design and handover acceptance,grounding impedance test of substation main grounding grid,grounding conduction test and excavation inspection of substation grounding grid and transformation of substation grounding Gird in Jiangxi power grid,the main problems existing in operation and maintenance of main grounding are summarized.Finally,through the combination of on-site measurement and numerical analysis of Daxi110 kV substation,the current state evaluation and long-term development evaluation of the system are combined.After verifying the reliability of the numerical analysis method using CDEGS software by using the measurement results,combined with the analysis of the safety limit value of the grounding grid,the operation status of the grounding grid of Daxi substation is summarized,and the diagnosis is made through the analysis of various measurement data.The operation status of grounding device is used to evaluate the safety performance of grounding grid in Daxi substation under power frequency short circuit.