Current transformer secondary side circuit and disconnection detection method thereof

Abstract

The invention discloses a current transformer secondary side circuit and a disconnection detection method thereof. The circuit comprises a current transformer, a secondary side parallel resistor of the current transformer, an adjustable current source and an ADC chip. The detection method comprises the following steps of sampling the ADC chip to obtain an ADC sampling value, judging whether the sampling value of the ADC is greater than the secondary side parallel resistor resistance value Rs * the initial value I0 of the primary side current, if the ADC sampling value is greater than Rs * I0,judging the transformer is not disconnected, if the ADC sampling value is equal to 0, judging the transformer is not disconnected, and if the ADC sampling value is equal to Rs * I0,continuously adjusting the current of the Is linearly N times, judging the change condition of the ADC sampling value, wherein the Is is the current value of the adjustable current source. Whether the secondary side ofthe current transformer is disconnected or not can be quickly and accurately judged in real time, the influence of current transformer disconnection on a power system is reduced to the minimum, harm caused by current transformer secondary side disconnection is avoided, and reliable, safe and stable operation of a power grid is guaranteed.

Description

technical field [0001] The invention relates to the technical field of power system safety detection, in particular to a secondary side circuit of a current transformer and a disconnection detection method thereof. Background technique [0002] In order to ensure the safe and economical operation of the power system, it is necessary to monitor and measure the operation of the power equipment. The primary winding of the current transformer is connected in series with the high-voltage transmission circuit, and the secondary winding is connected with secondary equipment such as measuring instruments and protection devices, which is related to the accuracy of measurement and measurement, the reliability of the relay protection device and the safety of the high-voltage transmission circuit. . There are different degrees of vibration during the transportation and operation of the current transformer, and the quality of the current transformer itself is relatively heavy, and the c...

AI Technical Summary

Problems solved by technology

The alternating magnetic flux induces a suspended high voltage on the secondary side coil of the current transformer, and its peak value can sometimes reach tens of thousands of volts. Such a high voltage acts on the secondary circuit of the current transformer and the secondary side coil , will seriously threaten the safety of equipment and personal safety, and may even cause the insulation of the current transformer coil to burn out due to overheating, resulting in the failure of the protection device to disconnect the corresponding circuit breaker because the fault current cannot be detected, causing the fault to expand and cause a large-scale power outage serious accident

For zero-sequence current protection and differential protection, it may malfunction due to the unbalanced current generated when the circuit is open

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