The Synthetic Monitoring Approach And Realization For Grounding Grids

Grounding grids are essential to ensure the power system running security and personal safety in power substations and plants. In our country, the methods to test the status of gournding grids include measuring the grounding resistance and resistance of network connectivity combined with partial excavation. However, these approaches indeed bring about some disadvantages such as the bulky measuring facilities, difficult manipulation and inaccurate test results. Thus, this dissertation deals with all-around grounding grid monitoring without excavation or power off.By analyzing weaknesses of existing grounding grid monitoring approaches, a new method for measuring the corrosion status and the parameters of grounding grids is proposed. The corrosion state of the grounding grid is simulated by optimizing the position of corrosion sensors in soil. The parameters including grounding grid corrosion rate and corrosion depth are measured based on the proposed quasi-steady-state measurement technique. Then, by building the database reflecting the relation of the grounding grid running time, corrosion depth and grounding resistance, the grounding resistanc value is obtained. The change of the grounding grid status is analyzed. Again, taking into account of many factor such as the soil frame, testing noise and so on, this paper presented the corresponding hardware and software filtering methods so as to reduce system measurement error. The proposed filtering methods effectively remove the interference signals in the spot of grounding grid and improve the accuracy of the measurement.Furthermore,this paper studies the hardware design and realization of the synthetic monitoring and analysis system and introduces its software implementation design. Hardware design of sub-module systems is performed based on PC104 design rule. The sub-module systems consist of the main central control module, signal processing module, quasi-steady-state measurement module, resistance measurement module, power module and so on. The superiority of this design is full-featured, small size, low power-consumption and easy upgrade. The reliability analysis of hardware and software design shows that the system including hardware and software has prospective reliability and stability.Based on the proposed approach, the synthetic monitoring and analysis system for grounding grids is developed. The simulation experiments and locale experiments prove that the system can monitor and analyze corrosion depth, corrosion velocity and grounding resistance with satisfactory accuracy and speed.