Fault detection method for current transformer of grid-connected inverter

The current transformer fault is identified by applying disturbances in the control loop of the grid-connected inverter, which solves the false alarm problem and improves the identification accuracy and user experience.

CN120122049APending Publication Date: 2025-06-10NINGBO GINLONG TECH
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Patent Information

Application Number
CN202510476352.2
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-04-16
Publication Date
2025-06-10

AI Technical Summary

Technical Problem

The existing grid-connected inverter cannot be effectively identified when the current transformer fails, resulting in a false alarm of 'electric meter CT failure', affecting the user experience.

Method used

By applying a disturbance of a duration of Δt1 in the control loop of the grid-connected inverter, and continuously detecting the feeding current of the phase, if the feeding current of the phase continues to 0 after the duration of Δt2, and after the accumulation reaches the set value n, it is determined that the 'electric meter CT fault' occurs in the phase.

Benefits of technology

It improves the accuracy of current transformer fault identification, reduces false alarms, improves user experience, does not increase costs, and does not affect the normal anti-countercurrent control method.

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Abstract

The invention discloses a fault detection method for a current transformer of a grid-connected inverter, and the method comprises the following steps: assigning a counter to be 0 when it is detected that the current of a certain phase of a feed network is kept to be 0 for a time t; applying disturbance with the duration of delta t1 to a control loop of the grid-connected inverter, and continuously detecting the feed network current of the phase; if the current of the feed network of the phase is continuously 0 after the time length delta t2, assigning the counter to be 1, otherwise, clearing the value of the counter and ending the fault judgment; the disturbance applying process is repeated, and after the counter accumulates to reach the set value n, it is judged that the phase has the electric meter CT fault. Compared with a traditional mode, the current transformer fault identification method has the beneficial effects that the accuracy of current transformer fault identification can be improved by applying disturbance under the conditions that the cost is not increased and a normal anti-countercurrent control method is not influenced, so that the user experience is improved.
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