The arc suppression coil is an inductor coil with an iron core. It is connected between the neutral point of the transformer (or generator) and the ground to form the arc suppression coil grounding system. During normal operation, no current flows through the arc suppression coil. When the power grid is struck by lightning or a single-phase arc grounding occurs, the neutral point potential will rise to the phase voltage. At this time, the inductive current flowing through the arc suppression coil and the single-phase grounding capacitive fault current cancel each other out, so that the fault current After being compensated, the residual current after compensation becomes very small, which is not enough to maintain the arc, and then extinguish itself. In this way, the ground can be eliminated quickly without causing overvoltage.
After the arc suppression coil is installed in the power grid, when a single-phase grounding occurs, the arc suppression coil generates an inductive current. The inductive current compensates for the capacitive current formed by the single-phase grounding, which reduces the grounding current and reduces the fault phase recovery voltage speed. Hazard caused by excessive capacitor current. At the same time, due to the clamping effect of the arc suppression coil, it can effectively prevent the generation of ferromagnetic resonance overvoltage. The better the arc extinguishing coil compensation effect, the greater the safety protection effect on the power grid, so the arc extinguishing coil needs to be automatically tuned to track the change of the capacitor current.
The arc extinguishing device can automatically track changes in the parameters of the power grid, automatically measure the capacitor current, and automatically adjust the compensation current. Both over and under compensation can be operated, and the method is very flexible. Can well suppress arc ground overvoltage, disconnection overvoltage and transfer overvoltage. The tuning methods of the arc suppression coil can be divided into two types: pre-adjustment and follow-on adjustment. According to the adjustment method of the arc suppression coil reactance, it can be divided into electric on-load adjustable turn type, DC bias magnetic type, air-gap type, capacity-regulated type and so on.
With the rapid development of power electronic devices, the single-tube capacity and reverse voltage of thyristors have been greatly improved, and the performance is stable. At present, the intelligent arc-suppression coil automatic tracking ground compensation device produced by our company realizes the use of fast-acting arc-suppression coil compensation to automatically eliminate transient single-phase ground faults, while non-transient single-phase ground faults are kept as short as possible. Selecting and tripping the ground fault line within time will not affect the power supply reliability of the power grid and reduce the insulation requirements of the system equipment. It can be applied to distribution networks with any structure such as overhead lines, cable lines or any combination of them. It is based on the concept of a thyristor switching capacitor bank, and a parallel capacitor bank of different capacity is arranged on the secondary winding of the arc suppression coil, and a new type of TSC type arc suppression coil is constructed. The arc extinguishing coil has fast tuning speed, wide adjustment range, and has the characteristics of step and linear adjustment, no harmonic pollution, high reliability, and low loss and noise, which improves the safety of power grid operation and the quality of power supply.