Intelligent Substation Maintenance Pressure Plate Operation Guide

According to the "Eighteen Major Anti-Accident Measures for Power Grid of State Grid Corporation of China (Revised Edition)" promulgated in 2018, operation and maintenance units should improve the on-site operation regulations for intelligent substations, refine the usage instructions and abnormal handling methods for various messages, signals, hard pressure plates, and soft pressure plates of intelligent equipment, standardize the operation sequence of pressure plates, strictly follow the sequence during on-site operations, and check the alarm signals of protection before and after operations to prevent misoperation accidents.

As a core component of protection devices, merging units, intelligent terminals, and measurement and control devices in intelligent substations, the correctness of maintenance pressure plate operation sequence is of great significance to switch operation during faults.

The operation principles for maintenance pressure plates in intelligent substations are as follows:

a) Before operating the maintenance pressure plate of a protection device, it should be confirmed that the protection device is in signal state, and the soft pressure plates (such as failure start soft pressure plates, etc.) of the secondary circuits of related operating protection devices (such as bus differential protection, safety automatic devices, etc.) have been withdrawn.

b) When primary equipment is out of service, before operating the maintenance pressure plate of the bay merging unit, it is necessary to confirm that the SV soft pressure plates of related protection devices have been withdrawn, especially for protection devices that continue to operate. When primary equipment is not out of service, the merging unit maintenance pressure plate can only be engaged after the related protection devices are in signal state or disabled. For bus merging units, when primary equipment is not out of service, the merging unit maintenance pressure plate can only be engaged after handling according to bus voltage abnormality procedures and applying for changes to the corresponding relay protection operation mode as needed.

c) When primary equipment is out of service, before operating the maintenance pressure plate of the intelligent terminal, it should be confirmed that the "edge (middle) circuit breaker set to maintenance" soft pressure plate of the related line protection device has been engaged (if available). When primary equipment is not out of service, it should first be confirmed that the outlet hard pressure plate of the intelligent terminal has been withdrawn, and after withdrawing the protection reclosing function and engaging the forced soft pressure plate of the corresponding isolation switch of the bus protection as needed, the maintenance pressure plate of the intelligent terminal can be engaged.

d) After operating the maintenance pressure plates of devices such as protection devices, merging units, and intelligent terminals, the device indicators, human-machine interface state change messages, or input state changes should be checked, and it should be verified whether related operating devices have unexpected signals. Only after confirming normal operation can subsequent operations be performed.

When primary equipment is returned to service and the relay protection system is put into operation, operations should preferably be performed in the following sequence:

• Withdraw the maintenance pressure plates of the bay merging unit, protection device, and intelligent terminal

• Engage the SV soft pressure plates of this bay in related operating protection devices

• Engage the GOOSE receive soft pressure plates of this bay in related operating protection devices

• Engage the GOOSE send soft pressure plates for tripping, reclosing, failure initiation, etc. of the protection device in this bay

• Engage the outlet hard pressure plate of the intelligent terminal in this bay

When primary equipment is out of service and it is necessary to withdraw the relay protection system, operations should preferably be performed in the following sequence:

• Withdraw the GOOSE receive soft pressure plates (such as failure initiation, etc.) of this bay in related operating protection devices

• Withdraw the GOOSE send soft pressure plates for tripping, closing, failure initiation, etc. in the protection device of this bay

• Withdraw the SV soft pressure plates or bay engagement soft pressure plates of this bay in related operating protection devices

• Withdraw the outlet hard pressure plate of the intelligent terminal in this bay

• Engage the maintenance pressure plates of the protection device, intelligent terminal, and merging unit in this bay