First, relay protection fault analysis

1, current mutual inductance saturation fault

The saturation of current transformer to the relay protection of power system is very large. With the increase of the terminal capacity of the distribution system equipment, the short circuit current will be large if a short circuit occurs. If the system shorts near the terminal equipment area, the current may reach or approach 100 times or more of the rated current of a single current transformer. Under normal short-circuit condition, the error of current transformer increases with the increase of primary short-circuit current multiple. Prevents action when current rate break protection reduces sensitivity. When the line is short circuited, because the current of the current transformer is saturated, the secondary current detected again is small or close to zero, and the fixed time overcurrent protection device cannot be extended. When the outgoing overcurrent protection action of the distribution system causes the incoming protection action of the distribution system, the entire distribution system will stop.

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2. Improper selection of switch protection device

The choice of switch protection device is very important. At present, most substations are located in high-load areas, that is, the power supply and transmission methods are as follows: Foshan Substation. For the switch station that has not realized the automation of relay protection, the load switch or relay protection device system should be used as the switch protection device.

Second, the relay protection system fault treatment methods and measures

1, the common treatment method of relay protection failure

1) Alternative methods

Replacing the faulty unit with a complete unit and judging the quality of the faulty unit can quickly reduce the scope of fault search;

2) Reference method

By comparing the relevant technical parameters of the normal device and the abnormal device, the fault point of the abnormal device is found. This method is mainly used to detect wiring errors and faults when the test value is inconsistent with the expected value in the process of constant value detection. If secondary cables cannot be correctly connected after the device is modified or replaced, refer to similar devices. In the relay calibration, if the test value of the relay is found to be far from the set value, it is not easy to judge the characteristics of the relay, and the calibration value on the relay should be adjusted. The same instrument can be used to measure other similar relays in the same circuit for comparison;

3) Short connection method

Short-circuit a part or part of a circuit to determine whether the fault is within the short-circuit range or elsewhere, thereby determining the fault range. This method is mainly used for electromagnetic lock failure, current circuit open, switching relay does not operate, and judging whether the switch contact is good.