The disadvantages of grid-connected distributed photovoltaic power generation systems can be categorized into three classes (I, II, III) based on the severity of the drawbacks. Class I and II drawbacks are classified as critical and serious issues, while Class III refers to minor deformities with less impact on safe operation.
The scope of defect protection includes both the grid-side of the public power grid and the grid-side of the distributed photovoltaic power generation system. In the document issued by the State Grid Corporation of China in 2013, "Opinions on the Task of Providing Grid Connection Services for Distributed Power Sources," it is stipulated: "The grid connection projects of distributed power sources that connect to the public power grid, including the grid connection project (inclusive of communication special networks) and the part of the public power grid transformation caused by the connection, shall be invested and constructed by the company for the distributed power source projects at the user side. The grid connection project is invested and constructed by the project owner, and the part of the public power grid transformation caused by the connection is invested and constructed by the company." Based on this principle, the scope of defect protection is determined: the grid-side defect protection of the public power grid is handled by the power supply department for follow-up maintenance, and the grid-side of the distributed photovoltaic power generation system is handled by the project owner for follow-up maintenance.
After the distributed photovoltaic power generation system is grid-connected, the following precautions for defect management should be noted:
(1) Defect Management adheres to the closed-loop governance principles, with the entire process of the closed-loop governance program including: Identify Defects - Cancel Defects - Evaluate Defects - Control Inspection - Eliminate Defects - Operation Acceptance.
(2) When a distribution operation and maintenance staff identifies a defect, it should be classified according to the severity level into minor defects (Class III), major defects (Class II), and critical defects (Class I). Tasks should be assigned based on the severity of the defect and corrective actions should be carried out.
(3) Deficiencies are reported by the team to the Distribution Operation and Maintenance section's responsible personnel. For deficiencies that do not require further reporting, the responsible personnel in the Distribution Operation and Maintenance section will stop the assessment and assign them to the section's inspection responsible for deficiency elimination. For deficiencies that require further reporting, they should be reported and assigned for elimination in a timely manner.
(4) Develop, on schedule (or in real-time), the statistics, analysis, and reporting of defects in distribution operation and maintenance, identify the causes and patterns of defect occurrence, and grasp the elimination scenarios, adopting targeted preventive measures.
(5) Power grid equipment shutdown for defect elimination and inspection should be communicated in advance to users of the distributed photovoltaic power generation system. Defect rectification for abnormal defects should be conducted in accordance with the shutdown schedule request prior to the main shutdown of the distributed photovoltaic system; during emergency defect handling, the distributed photovoltaic power generation system can be directly disconnected to isolate the fault; the handling of severe defects should be determined based on the specific situation.
(6) The equipment protection section shall handle defects that do not require power shutdown independently and dispose of them; defects requiring power shutdown should be reported with the monthly power shutdown plan.
(7) Upon completion of defect handling for Class I, II, and III defects, the Distribution Operation and Inspection Department (Operation and Governance Department) will cease acceptance. At the beginning of each month, the Equipment Protection Department and the Operation and Governance Department should stop compiling statistics on the previous month's defect handling situations.
(8) In the Operations and Maintenance Governance section, a dedicated person for defect management should be appointed, primarily responsible for the operation inspections, defect reporting, and classification of defects for the equipment under their jurisdiction.
Defect reporting and defect handling processes rely on operational staff for monitoring and inspection personnel conducting on-site inspections to identify defects and report them.
