Circuit for determining lockout states of lockout relays

Abstract

The invention discloses a circuit for determining lockout states of lockout relays, which solves the technical problem of correctly determining contact states of the lockout relays. The circuit is respectively provided with an A-phase trip lockout relay, a B-phase trip lockout relay, a C-phase trip lockout relay and a holding relay, a series circuit with large resistors, an A-phase trip circuit supervision optical coupler, a B-phase trip circuit supervision optical coupler and a C-phase trip circuit supervision optical coupler are parallelly connected into a series circuit with contacts of the A-phase trip lockout relay, the B-phase trip lockout relay, the C-phase trip lockout relay and a coil of the holding relay, and the optical couplers are current starting type optical couplers. Compared with the prior art, the circuit has the advantages that the large resistors and the current starting type optical couplers are parallelly connected onto the contacts of the lockout relays, the states are fed back to a CPU (central processing unit) of intelligent terminal equipment, and the intelligent terminal equipment determines whether the lockout relays are correctly closed or not by determining state changes of input of the optical couplers during execution after receiving a protection command of an electric power system and tripping and closing commands of measurement and control equipment, so that the influence of unreliable factors of an autoeciousness circuit on the electric power system is eliminated.

Description

technical field [0001] The invention relates to a monitoring circuit of a smart grid in a power system, in particular to a circuit for judging the contact state of an outlet relay of an intelligent terminal. Background technique [0002] In the smart grid of the power system, the intelligent terminal equipment is used as the direct control equipment of the power system circuit breaker, and the reliability of its action is directly related to the safety and stability of the power system. When the intelligent terminal equipment receives the command of the intelligent protection of the power system and the opening and closing of the circuit breaker of the measurement and control equipment, can it correctly and faithfully reflect the export status of the export relay, analyze and recall the cause of the power system accident, and realize the online monitoring of the smart grid, All have great significance. [0003] In the power system, it is necessary to monitor whether the int...

AI Technical Summary

Problems solved by technology

Compared with the first method, this method greatly enhances the correctness of monitoring, but whether it is correct or not is based on the assumption that the characteristics of the exit relay are intact. There are differences in the reached current and voltage thresholds, or the outlet relay itself is damaged during the operation of the power system, and there are also monitoring blind spots

[0007] 3. Connect an optocoupler power supply and a voltage-activated optocoupler input in parallel on the outlet relay contact, and directly connect an optocoupler input circuit in parallel at the outlet relay contact, which can reflect the status of the export relay in real time. There is a light in series in the optocoupler input circuit The optocoupler power supply required for coupling start will bring new problems: in the power system, the outlet relay contacts are connected in series with the circuit breaker tripping and closing coils to control them, and are connected in parallel to the outlet relay contacts. The optocoupler open-in circuit is actually connected in parallel in the operation circuit of the circuit breaker tripping and closing coil, which obviously belongs to the parasitic circuit of the operation circuit and has a certain impact on the safety and stability of the power system.

[0008] Through the comparison of the above several methods, it can be seen that if we want to implement real-time monitoring of the exit relay completely by adding hardware without increasing the parasitic circuit of the circuit breaker jumping and closing coil, non-electrical methods such as laser measuring the exit are adopted for the exit relay. The distance of the relay contacts, but the cost of the equipment is too high

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