Standard Procedures for Substation Fault and Defect Handling

I. Fault Management

(1) Basic Principles of Fault Handling

• Rapidly restrict the development of the fault, eliminate the root cause, and remove threats to personnel, power grid, and equipment safety.

• Adjust and restore normal power grid operation modes. If the grid has split, quickly restore synchronization.

• Maintain operation of healthy equipment and ensure continuous power supply to critical users, plant service loads, and substation auxiliary power.

• Restore power supply to de-energized users and equipment as soon as possible.

(2) Fault Handling Procedures

• Operation and maintenance (O&M) personnel shall promptly arrive at the site for preliminary inspection and judgment, and report weather conditions, monitoring information, and a brief summary of protective relay actions to dispatch and control personnel.

• If work is ongoing at the site, notify personnel to stop work and preserve the scene; determine whether the work is related to the fault.

• When a substation’s auxiliary power is lost or the system loses its neutral grounding point, change the operating mode and adjust relay protection settings according to dispatch instructions.

• Conduct a detailed inspection of protective relay and automatic safety device signals, including fault phase, fault location, and other fault data. Reset signals, comprehensively analyze the fault nature, location, and affected power outage range, then inspect equipment within the protection zone. Report findings to dispatch and superior management.

• After identifying the faulty equipment, isolate the fault point as instructed by dispatch and restore power to unaffected equipment.

(3) Fault Reporting Requirements

Immediate Reporting:

When a system fault occurs, relevant O&M units shall immediately report to the corresponding dispatch center:

• Fault occurrence time;

• Changes in the status of primary equipment at the substation after the fault;

• Whether any equipment parameters (voltage, current, power) exceed limits, and whether any equipment requires emergency control;

• Weather conditions and other directly observable phenomena.

Manned Substations:

• Within 5 minutes: Report protective relay and automatic safety (referred to as "safety control") device actions, fault type, circuit breaker tripping, and reclosing operation status.

• Within 15 minutes: Provide a preliminary inspection of primary and secondary equipment, confirm whether protection and safety control devices operated correctly, and determine if test energization is feasible.

• Within 30 minutes: Report all protective relay actions, fault location results, and transmit event records, fault oscillography, fault reports, and on-site photos as required by dispatch.

• Unmanned Substations:

• Within 10 minutes (Monitoring Center): Report protective relay and safety control actions, fault type, circuit breaker tripping and reclosing status, and notify O&M personnel to proceed to the site.

• Within 20 minutes (Monitoring Center): Report all protective relay actions and fault location results; confirm whether all protection and safety control devices operated correctly; determine if remote test energization is feasible based on conditions.

• Within 20 minutes after O&M personnel arrive on site: Provide a preliminary inspection of primary and secondary equipment. If the faulty equipment remains out of service, on-site personnel shall confirm test energization feasibility, supplement the report on all protective actions and fault location, and transmit event records, fault oscillography, fault reports, and on-site photos as required.
  Note: Reporting time requirements may vary slightly among different dispatching authorities; always follow the specific requirements of the responsible dispatch center.

II. Defect Management

(1) Defect Classification

Critical Defects
Defects that directly threaten safe operation and must be handled immediately; otherwise, they may lead to equipment damage, personal injury, widespread blackouts, or fire at any moment.

Serious Defects
Defects posing serious threats to personnel or equipment that can temporarily remain in service but must be addressed as soon as possible.

General Defects
All other defects not classified as critical or serious—typically minor in nature, with limited impact on safe operation.

(2) Defect Identification, Documentation, and Reporting

• Defects identified by maintenance or testing personnel shall be promptly communicated to O&M personnel.

• After discovery, the O&M team shall classify the defect according to established standards and initiate the defect management process promptly.

• When registering defects in the PMS (Production Management System), entries must strictly follow the defect standard library and actual field conditions, including: main equipment, component, component type, defect location, description, and classification basis.

• For defects not covered in the standard library, classification shall be based on actual conditions, with clear documentation of the defect details.

• For defects that cannot be clearly classified, the higher-level unit shall organize a review to determine the classification.

• Critical or serious defects that may affect the operation mode of primary/secondary equipment or centralized monitoring shall be reported to the corresponding dispatch personnel. Until resolved, O&M personnel shall increase inspection frequency.

(3) Defect Handling

• Defect Handling Timeframes:

• Critical defects: resolved within 24 hours;

• Serious defects: resolved within 1 month;

• General defects requiring outage: resolved within one maintenance cycle;

• General defects not requiring outage: resolved within 3 months (in principle).

• Upon discovering a critical defect, immediately notify dispatch personnel to take emergency measures.

• Before critical or serious defects are resolved, the O&M unit shall develop preventive measures and emergency response plans based on the defect condition.

• For defects affecting remote control operations, prompt handling is required. Both before and after resolution, the dispatch center must be informed, and records maintained. Remote control tests may be conducted in coordination with the dispatch center if necessary.

(4) Defect Resolution Verification (Acceptance)

• After defect handling, O&M personnel shall conduct on-site verification to confirm the defect has been eliminated.

• Upon successful acceptance, after maintenance personnel have recorded the handling details in the PMS, O&M personnel shall enter the acceptance comments into the PMS to complete the closed-loop management process.