Ship power system insulation low protection method based on grounding current detection

Abstract

The invention relates to a ship electric power system insulation low protection method based on grounding current detection, which comprises the following steps: receiving grounding current information and insulation monitoring information, and when the maximum value of the grounding current in a power supply area exceeds a set threshold value and a branch insulation low alarm sent by an insulation monitoring device is received, keeping the above state for a set delay time; if yes, the corresponding load branch switch is cut off, and the fault branch is cut off. The problem that conventional arc light protection is not suitable for medium-voltage direct-current occasions where air circuit breakers are applied is solved, the application range of arc light protection is widened, and the bus protection in a medium-voltage direct-current distribution board cabinet is achieved. Only a current sensor, an arc light sensor and a comprehensive controller which are deployed by conventional arc light protection are adopted, no additional sensor is arranged, the adaptability is improved only by adding judgment logic, and no additional implementation cost is brought.

Description

Technical Field

[0001] The present invention relates to the technical field of ship power system protection, and in particular to a ship power system insulation low protection method based on ground current detection. Background Art

[0002] In the ship's DC power system, the monitoring and protection of the insulation status of the power supply branch is one of the key technologies to ensure the safe and stable operation of the power system. When the insulation level drops, how to effectively isolate the faulty part and restore the system operation is the focus of the research. At present, a comprehensive protection device is used to monitor the system grounding current in real time. When the grounding current exceeds the limit, the protection device alarms and disconnects the unit switch; by configuring the insulation monitoring device, each load branch is monitored and low insulation warning is issued. However, the accuracy of the current insulation monitoring device is poor. When there is an insulation problem in the load branch, the reliability of directly using the output of the insulation monitoring device to cut off the faulty branch is low, but directly cutting off the unit switch will cause the power failure range to expand. Therefore, improving the accuracy of low insulation identification and enhancing protection reliability are one of the current research directions of this protection. Summary of the invention

[0003] In view of the above-mentioned insulation problem of ship power system, a low insulation protection method of ship power system based on grounding current detection is proposed to improve the accuracy and reliability of low insulation protection of ship power system.

[0004] The technical solution of the present invention is: a method for low insulation protection of a ship power system based on grounding current detection, which receives grounding current information and insulation monitoring information. When the maximum value of the grounding current in the power supply area exceeds a set threshold and a branch insulation low alarm sent by an insulation monitoring device is received, the above state is maintained for more than a set delay time, and the corresponding load branch switch is cut off to achieve the removal of the fault branch.

[0005] A ship power system low insulation protection system, which implements the ship power system low insulation protection method based on ground current detection, comprises a comprehensive protection device, a centralized control comprehensive protection, and an insulation monitoring host, wherein the comprehensive protection device comprises a unit screen comprehensive protection and a load branch comprehensive protection;

[0006] The unit screen comprehensive protection collects the grounding current of the corresponding unit and sends the collected value to the power station centralized control comprehensive protection through the CAN1 network;

[0007] The load branch comprehensive protection receives the low insulation alarm information sent by the centralized control comprehensive protection, and controls the low insulation indicator light of this screen to light up; receives the opening control signal sent by the centralized control comprehensive protection, and executes the circuit breaker opening control;

[0008] The insulation monitoring host monitors the low insulation alarm information sent by the load branch comprehensive protection, and sends the corresponding branch insulation low alarm information and the cross-branch connection status to the power station centralized control comprehensive protection through the CAN2 network;

[0009] The centralized control and comprehensive protection system receives the branch insulation low alarm sent by the insulation monitoring host through the CAN2 network, and forwards the alarm information to the various centralized control and comprehensive protection systems of this power station through the CAN1 network; receives the grounding current information collected by the panel comprehensive protection system of the unit of this power station through the CAN1 network; collects the maximum value state of the grounding current determined by the centralized control and comprehensive protection system of the opposite power station through the switch quantity, and outputs the maximum value state of the grounding current of the unit of this power station through the switch quantity; combines the branch insulation low alarm information, the jumper switch state, and the grounding current information to perform insulation monitoring fault delayed tripping logic judgment, sends a tripping control signal through the CAN1 network, and cuts off the load branch of this power station where the insulation fault occurs.

[0010] The beneficial effects of the present invention are as follows: the low insulation protection method of the ship power system based on ground current detection of the present invention solves the problem that conventional arc protection cannot be applied to medium voltage DC occasions using air circuit breakers, improves the application scope of arc protection, and solves the implementation difficulty of busbar protection in medium voltage DC distribution board cabinet; only current sensors, arc sensors and integrated controllers deployed by conventional arc protection are used, without additional sensors, and the adaptability is improved only by adding judgment logic, without bringing additional implementation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a diagram of a method for low insulation protection of a ship power system based on ground current detection according to the present invention;

[0012] Figure 2 This is the information flow diagram of the low insulation protection system of the ship power system of the present invention. DETAILED DESCRIPTION

[0013] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0014] The present invention proposes a low insulation protection method for a ship power system based on ground current detection, which comprehensively utilizes ground current information and insulation monitoring information to identify the low insulation fault state of the load branch of the power system and accurately cut off the faulty branch. The protection method is: when the maximum value of the ground current in the power supply area exceeds the set threshold and the branch insulation low alarm sent by the insulation monitoring device is received, the above state is maintained for more than the set delay time, then the corresponding load branch switch is cut off.

[0015] The protection method realizes the required low insulation protection system of the ship power system. The system consists of: comprehensive protection device, centralized control comprehensive protection, and insulation monitoring host. The communication network uses CAN bus. The equipment connection diagram in the system is as attached. Figure 1 shown.

[0016] The devices are allocated as follows:

[0017] 1. Comprehensive protection of unit screen

[0018] Collect the grounding current of the corresponding unit and send the collected value to the centralized control and comprehensive protection of the power station through the CAN1 network.

[0019] 2. Comprehensive protection of load branch

[0020] 1) Receive low insulation alarm information sent by the centralized control and comprehensive protection, and control the low insulation indicator light on this screen to light up;

[0021] 2) Receive the opening control signal sent by the centralized control and comprehensive protection system, and execute the circuit breaker opening control.

[0022] 3. Insulation monitoring host

[0023] Monitor the low insulation alarm information sent by the load branch comprehensive protection, and send the corresponding branch low insulation alarm information and the interconnection status of the cross-connected branch to the centralized control comprehensive protection of this power station through the CAN2 network.

[0024] 4. Centralized control and comprehensive security

[0025] The front and rear power stations of the ship are each equipped with a centralized control and comprehensive protection system, which has the following functions:

[0026] 1) Receive the branch insulation low alarm sent by the insulation monitoring host through the CAN2 network, and forward the alarm information to each centralized control and comprehensive protection of the power station through the CAN1 network;

[0027] 2) Receive the grounding current information collected by the comprehensive protection of the power station unit screen through the CAN1 network;

[0028] 3) The maximum grounding current state determined by the centralized control and comprehensive protection of the opposite power station is collected through switch quantity, and the maximum grounding current state of the power station unit is output through switch quantity.

[0029] 4) Combined with the branch insulation low alarm information, jumper switch status, and ground current information, the insulation monitoring fault delay trip logic judgment is performed, and the trip control signal is sent through the CAN1 network to cut off the load branch with insulation fault in this power station. The information flow is as follows Figure 2 shown.

[0030] In terms of communication design, this protection strategy adopts the following scheme:

[0031] 1) CAN1: Internal communication interface between centralized control and conventional comprehensive protection in a single power station, for information exchange on low insulation alarm, grounding current information, and tripping control.

[0032] 2) CAN2: Communication interface between centralized control and insulation monitoring host.

[0033] The communication reliability is designed as follows:

[0034] 1) Both CAN1 and CAN2 adopt dual network redundancy strategy. When the communication of network A is normal, the data of network A is adopted. When the communication of network A is disconnected, the data of network B is adopted.

[0035] 2) Set CRC check for the opening control instruction to reduce the risk of wrong opening;

[0036] 3) Set CRC check for communication messages with the insulation monitoring host to reduce the risk of false tripping and alarm;

[0037] 4) The comprehensive protection network in the power station is connected through an independent CAN1 network to ensure no interference from external equipment.

[0038] Centralized control and comprehensive security communication abnormal status processing:

[0039] 1) Communication interruption of insulation monitoring host: If no communication data from the insulation monitoring host is received for more than 5 seconds, the centralized control system will give an alarm and clear the low insulation alarm information and the connection status of the jumper branch.

[0040] 2) The unit panel comprehensive protection communication is interrupted: if the unit panel comprehensive protection communication data is not received for more than 5s, the unit panel comprehensive protection alarm will be triggered, the centralized control comprehensive protection display shows that the corresponding node comprehensive protection is offline, and the corresponding branch grounding current value will be reset to zero.

[0041] The above-mentioned embodiments only express the specific implementation of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A method for low insulation protection of a ship power system based on ground current detection, characterized in that: Receive grounding current information and insulation monitoring information. When the maximum grounding current in the power supply area exceeds the set threshold and the branch insulation low alarm sent by the insulation monitoring device is received, and the above state is maintained for more than the set delay time, the corresponding load branch switch is cut off to remove the fault branch.

2. A ship power system low insulation protection system, which implements the ship power system low insulation protection method based on ground current detection as described in claim 1, characterized in that: It includes comprehensive protection device, centralized control comprehensive protection and insulation monitoring host. The comprehensive protection device includes unit screen comprehensive protection and load branch comprehensive protection; The unit screen comprehensive protection collects the grounding current of the corresponding unit and sends the collected value to the power station centralized control comprehensive protection through the CAN1 network; The load branch comprehensive protection receives the low insulation alarm information sent by the centralized control comprehensive protection, and controls the low insulation indicator light of this screen to light up; receives the opening control signal sent by the centralized control comprehensive protection, and executes the circuit breaker opening control; The insulation monitoring host monitors the low insulation alarm information sent by the load branch comprehensive protection, and sends the corresponding branch insulation low alarm information and the cross-branch connection status to the power station centralized control comprehensive protection through the CAN2 network; The centralized control and comprehensive protection system receives the branch insulation low alarm sent by the insulation monitoring host through the CAN2 network, and forwards the alarm information to the various centralized control and comprehensive protection systems of this power station through the CAN1 network; receives the grounding current information collected by the panel comprehensive protection system of the unit of this power station through the CAN1 network; collects the maximum value state of the grounding current determined by the centralized control and comprehensive protection system of the opposite power station through the switch quantity, and outputs the maximum value state of the grounding current of the unit of this power station through the switch quantity; combines the branch insulation low alarm information, the jumper switch state, and the grounding current information to perform insulation monitoring fault delayed tripping logic judgment, sends a tripping control signal through the CAN1 network, and cuts off the load branch of this power station where the insulation fault occurs.

Images