The neutral point grounding method in power systems is a critical technical and economic decision that affects safety, power supply reliability, equipment protection, communication interference, and overvoltage control. It also plays a key role in determining the overall cost of grid infrastructure. Choosing the appropriate grounding method requires careful evaluation of both technical performance and economic feasibility.
In systems where the single-phase ground capacitance current remains within regulatory limits, ungrounded or traditional arc suppression coil grounding methods are often used. These options offer high power supply continuity, good safety for personnel and equipment, minimal communication interference, and lower initial investment. They are typically suitable for smaller-scale networks with simple structures and stable operation modes. However, it's important to regularly measure the single-phase ground capacitance current during grid development. If the current exceeds acceptable levels, the grounding method should be adjusted promptly to maintain system stability and safety.
Resistor grounding is another common approach, particularly beneficial in reducing overvoltage levels. This allows for lower insulation standards on cables, which can lead to cost savings. However, for overhead line systems—where most single-phase faults are temporary—this method may result in unnecessary tripping, increasing operational disruptions. In contrast, cable-based distribution systems rarely experience transient single-phase ground faults, making resistor grounding more effective in such cases. When the capacitance current reaches 150A or higher, and the fault current remains below 1000A, grounding through a resistor is generally recommended.
From a safety perspective, resonant grounding (using an automatic tracking compensated arc suppression coil) offers significant advantages in limiting the impact of single-phase ground faults. This method is increasingly becoming the preferred choice due to its adaptability and efficiency in both overhead and cable-based systems. For instance, in Berlin, even with currents as high as 4000A, resonant grounding is still used successfully. Modern arc suppression coils, especially those using thyristor-controlled technology, combine short-circuit impedance transformers and power electronics to provide precise and dynamic compensation. These advanced systems are gradually replacing traditional models, offering better performance and reliability.
In the Hai'an Power Grid, the neutral point is primarily ungrounded in 10kV and 35kV systems. Some areas, like the southern suburbs, have installed traditional arc suppression coils, but due to the increase in substation numbers, the grid’s capacitance current has dropped to just a few amps, making traditional coils difficult to adjust and now largely inactive. Recently, the new city 10kV system has adopted automatic tracking compensation arc suppression coils, improving performance and reliability. Plans are also underway to implement similar technology in the southern suburbs’ 10kV system, further enhancing grid safety and efficiency.
Ev Fuse,Electric Vehicle Fuses,Evpack-Fuse,Amp Fuse
Dongguan Andu Electronic Co., Ltd. , https://www.autoido.com