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用于110kV及以上系统及。该系统在单相接地时，另外两相对地电压基本不变，系统过电压较低，对110kV及以上系统抑制过电压有利，但此时接地电流很大，运行设备很难长时间通过此电流，接地相对地电压很低，甚至为零，系统电压严重不平衡，许多电气设备无法正常工作，必须及时切除接地点。大电流接地系统要求部分主变的中性点接地，避免单相接地时短路电流过大。这些主变必须有一个三角形接线的绕组，以构成零序通路，降低零序阻抗。主变的零序阻抗一般为正序阻抗的1/3，线路的零序阻抗一般为正序阻抗的3倍。

For 110kV and above system and. The system in single phase grounding, the other two relative to the voltage unchanged, the system voltage is low, the 110kV and above system to suppress the overvoltage favorable, but this time the ground current is large, it is difficult to long time operation of the equipment through the grounding current, relatively low voltage, or zero voltage serious don't balance, many electrical equipment can not work normally, should be promptly removed to take place. The neutral point of the main transformer is required to be grounded in the large current grounding system, so as to avoid the excessive short circuit current in the single-phase grounding. These main changes must have a winding of a triangular connection to form a zero sequence path and reduce the zero sequence impedance. The zero sequence impedance of the main transformer is generally 1/3 of positive sequence impedance, and the zero sequence impedance of the line is generally 3 times that of the positive sequence impedance.







作为220kV枢纽变电站的主变必须并列运行。其中一台主变的220kV侧中性点和110kV侧中性点必须直接接地，其他主变中性点通过间隙接地。好处是110kV侧零序阻抗稳定，有利于该110kV系统零序定值的计算和整定，零序过流保护的保护范围变化很小，容易保持其阶梯特性；未220kV系统提供稳定的零序电源，保持220kV系统零序保护的方向性和稳定性。主变220kV侧中性点和110kV侧中性点均加装间隙保护，保护动作跳开各侧断路器。

The main transformer substation, as the 220kV hub, must run side by side. The neutral point of the 220kV side of one main transformer and the neutral point of the 110kV side must be directly grounded, and the other main transformer neutral points are grounded through the gap. Good is the zero sequence impedance of 110kV side stability, facilitates the calculation of the 110kV value of the system zero and setting the scope of protection, zero sequence overcurrent protection change is small, easy to maintain its ladder characteristics; zero sequence power 220kV system to provide a stable, maintain zero sequence protection direction and stability of 220kV system. 220kV side of main transformer neutral point and the 110kV side of the neutral point are installed on each side of the gap protection, circuit breaker tripping protection action.







作为220kV负荷变电站的主变必须分列运行。此时所有主变的220kV侧中性点必须通过间隙接地，110kV侧中性点全部接地运行。所有主变不能相220kV系统提供零序电流，110kV侧零序阻抗稳定。主变220kV侧中性点加装间隙保护，保护动作跳开各侧断路器。

The main transformer of the 220kV load substation must be disaggregated. At this time, the neutral point of the 220kV side of all main changes must be grounded through the gap, and the neutral point of the 110kV side is all grounded. All main changes can not provide zero sequence current for the phase 220kV system, and the zero sequence impedance of the 110kV side is stable. 220kV side of main transformer neutral point gap protection installation, each side of the circuit breaker tripping protection action.







作为链式接线的220kV变电站，其220kV侧母线并列运行并有两个电源。虽然主变分列运行，但必须有一台主变的220kV侧中性点直接接地，其他主变的220kV侧中性点通过间隙接地。110kV侧中性点必须全部直接接地。主变220kV侧中性点加装间隙保护，保护动作跳开各侧断路器。

As a 220kV substation with chain connection, the 220kV side bus runs side by side and has two power supplies. Although the main transformer is disaggregated, the neutral point of the 220kV side of the main transformer must be directly grounded, and the 220kV side neutral point of the other main transformer is grounded through the gap. The neutral point of the 110kV side must be directly grounded. 220kV side of main transformer neutral point gap protection installation, each side of the circuit breaker tripping protection action.