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电网发生故障时

网址:www.xiaohuxianquan.com.cn  2022-06-02  作者:admin    阅读:

电网发生故障时,只在短时间内通过故障电流,中性点经小电阻接地电网发生单相接地故障时,高灵敏度的零序保护判断并短时切除故障线路液压钢坝,接地变压器只在接地故障至故障线路零序保护动作切除故障线路这段时间内起作用,其中性点接地电阻和接地变才会通过IR= (U为系统相电压,R1为中性点接地电阻,R2为接地故障回路附加电阻)的零序电路。
When a fault occurs in a power network, only through fault current in a short time and single-phase grounding fault occurs in a neutral point through a small resistance grounded power grid, high-sensitivity zero-sequence protection judges and removes the fault line for a short time. The grounding transformer only works during the period from the grounding fault to the zero-sequence protection action of the fault line removing the fault line, and the neutral-point grounding resistance and grounding transformer will be turned on. Zero-sequence circuit with over-IR= (U is the system voltage, R1 is the neutral grounding resistance, R2 is the additional resistance of the grounding fault circuit).
根据上述分析,接地变压器的运行特点是;长时空载,短时过载。 总之,接地变压器是人为的制造一个中性点,用来连接接地电阻。当系统发生接地故障时,对正序负序电流呈高阻抗,对零序电流呈低阻抗性使接地保护可靠动作。
According to the above analysis, the operation characteristics of grounding transformer are long time and short time overload. In short, the grounding transformer is manufactured artificially as a neutral point to connect the grounding resistance. When the grounding fault occurs in the system, the positive sequence negative sequence current has a high impedance and the zero sequence current has a low impedance, which makes the grounding protection operate reliably.