What are arc suppression and harmonic suppression? Arc suppression and harmonic suppression are generally used in systems where the neutral point is not grounded.
Arc suppression and harmonic elimination cabinet, also known as (microcomputer arc suppression and harmonic elimination line selection and overvoltage protection device), is used in the power industry in 3-35KV power systems with ungrounded neutral point, neutral point grounded through arc suppression coil, or neutral point grounded through high resistance. It can limit various overvoltages in the system, effectively improving the system's operational safety and power supply reliability.
Meanwhile, because arc grounding overvoltage lasts for a long time, the energy can easily exceed the surge arrester's withstand capacity, causing the surge arrester to explode. Furthermore, the high-amplitude overvoltage generated by arc grounding exacerbates the cumulative damage to solid insulation such as cables, and may even cause breakdown and explosion.
In a neutral-point ungrounded system, excessive zero-sequence capacitance (mainly formed by the capacitance to ground of lines and cables) increases the single-phase grounding current. When an intermittent ground fault occurs, it is difficult to extinguish the arc, resulting in arcing grounding, causing overvoltage, endangering system safety, and increasing the probability of electric shock injury or death. Therefore, arc suppression coils are generally required to compensate for the grounding current when it exceeds 10A.
When a nonlinear inductive load (such as a voltage transformer) exists between the system and ground in an ungrounded system, system disturbances are very likely to induce resonance between the zero-sequence capacitance and inductive reactance. As the resonant voltage increases, the nonlinear inductive reactance decreases, exacerbating the oscillation and eventually maintaining a high voltage level, causing a very high overvoltage to ground. This resonance is also called ferroresonance. This resonance can be eliminated or weakened by installing harmonic suppression devices on the secondary side of the voltage transformer. Below, we will look at several common harmonic suppression schemes in power systems.
To implement harmonic suppression measures in the distribution network, the selection of secondary harmonic suppression devices such as microprocessor-based harmonic suppression devices, as well as primary harmonic suppression devices such as neutral point harmonic damping resistors and harmonic suppression voltage transformers, should be determined based on the specific conditions of the distribution network. Ideally, primary and secondary harmonic suppression devices should be used in combination to complement each other's advantages. To ensure equipment safety, measures such as limiting intermittent arcing grounding overvoltages should also be taken while implementing harmonic suppression measures.
