Demarcation switching zero-sequence current protection setting value calculation method

Abstract

The invention discloses a demarcation switching zero-sequence current protection setting value calculation method, and the method comprises the following steps: respectively measuring a capacitive current of a power supply system, then calculating a constant current of a demarcation switch of the power supply system, and then judging that Idz value is greater than the capacitive current of a circuit of the demarcation switch; setting the direction of the capacitive current to point to a grounding point when a grounding fault happens to the system, judging that a zero-sequence current passing through a fault demarcation switch is the capacitive current of the system, and is not related with the capacitive current of the circuit, wherein a zero-sequence current passing through a non-fault circuit demarcation switch is the capacitive current of the circuit, and is not related with the capacitive current of the system. The method is advantageous in that the method prevents air humidity from affecting constant value calculation; the method prevents the unclear quality of a circuit load (the length of a cable circuit is not precise because the cable circuit is buried underground) from affecting the constant value calculation; and the method can prevent a constant value from being modified when the circuit is changed in a small scale, and reduces the workload.

Description

Technical field [0001] The present invention involves a power system power supply technology. Specifically, it is a calculation method for the fixed value of zero -sequence current to protect the setting value with high work efficiency and accurate computing. Background technique: [0002] With the development of the economy, customers' requirements for the quality of power supply are getting higher and higher, and the requests are as little as possible, and some customers have even put forward non -stop power -stop requirements.In the past, to eliminate ground faults, each line of the same bus was needed to stop the power outage, that is, the power outage one by one to eliminate the fault line.This will not only cause power loss, but also affect production and daily life. The reliability of power supply is complained by customers. In addition, the cable line is unable to judge. To find the cause of the cause, it can only be measured by instruments.However, the 10kV power supply...

AI Technical Summary

Problems solved by technology

In addition, the calculation of the fixed value is greatly affected by the nature of the load carried by the line and the weather

Especially when there is rainy and snowy weather, that is, when the air humidity is high, the capacitance current will become larger due to the influence of air humidity, resulting in a small calculated setting value. The influence of the weather cannot be accurately grasped, and it is easy to cause the boundary switch to malfunction.

When the length of the line changes, the fixed value will change accordingly. There is no certain elastic value range, and it is quite troublesome to change the fixed value.