On October 15, at the construction site of the 110 kV Suyang Substation in Dehua County, Quanzhou City, State Grid Quanzhou Power Supply Company was orderly manufacturing the cable heads and testing the ring main units of the 10 kV Suyang No. 2 Line to speed up the transformation of the distribution network.

Just as capillary connects artery to vein, distribution network connects energy production and conversion to terminal consumption, transporting electrical energy to every household.

Since 2022, State Grid Fujian Electric Power has been committed to a three-year action to comprehensively upgrade the distribution network. With unified planning and standards, the distribution network structure has been optimized and upgraded into an advanced distribution network with "high reliability of power supply, high source-load aggregation, high information integration, and high-quality services". It improves the quality of power supply, promotes energy transformation and meets the demand for electric energy for the high-quality development of the economy, society and people's lives.

Standard-based Technical Guidelines Empower High-quality Construction

To upgrade such a large-scale distribution network which covers a large amount of nodes and a wide area, unified standards, advanced technology and quality management are essential.

State Grid Fujian Electric Power focuses on top-level design and adheres to its standards. Earlier this year, the Technical Guidelines for Fujian Distribution Network Planning and Design were formulated based on regional characteristics. Following the principles of standardization, differentiation and practicality, it clarifies the construction standards of the target grid and the requirements for equipment selection. State Grid Fujian Electric Power implements the concept of smart, green, environmentally friendly and high-quality development, focusing on building a strong and guaranteed gulf-type distribution network and a flexible and resilient mountain-type distribution network and increase the return on investment in the distribution network.

The 10 kV Nanxi Line in Shouning County, Fujian Province is located in a mountainous area. With a long power supply radius, it is troubled by line segmentation and unreasonable connections. Earlier this year, State Grid Shouning County Power Supply Company started to transform the 10 kV Nanxi Line.

The Technical Guidelines for Fujian Distribution Network Planning and Design laid a theoretical basis for the transformation of the 10 kV Nanxi Line. According to Zhuang Changsheng, responsible person for the distribution network of the State Grid Shouning County Power Supply Company, the 10 kV Nanxi Line has derived three large branch lines. Compared with the two-section and one contact point model in the old reconstruction plan, the construction standard of "three sections and two contact points" in the Technical Guidelines is a more reasonable basis for reconstruction. It standardizes grid optimization, line load division and station area settings, rectifies line connections, reduces large branch lines and shortens power supply distance, improving the reliability of power supply.

Fujian is located along the coast and is susceptible to natural disasters such as typhoons and heavy rains. Difficulties in enhancing the resistance of distribution networks to multiple types of disasters have long plagued the distribution network in Fujian Province.

State Grid Fujian Electric Power focuses on research on disaster mechanisms of distribution networks, identification of weak links in disaster prevention, construction of disaster prevention backbone grids and differentiated design. Taking into account the distribution characteristics of various types of natural disasters such as strong winds, lightning strikes, rain, snow and ice and their impact on the distribution network, it draws a disaster zoning map of the distribution network in Fujian Province down to the township (street) dimension. In addition, it associates and matches the design standards of disaster prevention of the distribution network to each town, effectively supporting the differentiated design of the distribution network's disaster prevention and improveing the intrinsic safety of the distribution network.

Ultra-fast Self-healing Faults under Intelligent Management and Control

Distribution network is an essential and critical infrastructure in city. Constructing a world-class urban agglomeration requires a world-class urban distribution network that matches it.

Not long ago, Mr. Chen, who lives in Jinfu Xincun Community, Fuzhou City, Fujian Province, suffered a power outage at his home. Almost at the same time, he received a text message from the power supply company notifying him of the power outage. Within 10 minutes, power supply employees visited his home for emergency repairs. "We didn't ask for repairs but the staff came right away. What a considerate service!"

Mr. Chen's good experience with electric power services benefited from the efforts of Fujian Fuzhou Power Supply Company. In the construction of world-class urban distribution networks, it carries out low-voltage active emergency maintenance based on smart distribution stations and HPLC smart meter transformation, building a full-chain management system of power supply reliability.

The distribution network in the Gulou area where Mr. Chen lives has been fully upgraded. It has realized full-service, full-process and full-data information interconnection, ensuring panoramic perception of medium and low voltage status and always-on operation and inspection services.

State Grid Fujian Electric Power has been advancing the construction of power distribution automation and building an intelligent management and control system with "accurate sensing, rapid processing, ultra-fast self-healing and rapid power restoration." As users no longer have to go out for help when faults occur, branch line faults no longer expand into main line and segmented faults no longer affect substations, customers' experience is further optimized.

At 17:14:48 on June 27, strong convective weather caused a short circuit on the 10 kV Yuanmo Line of Yuankeng Substation in Shunchang County, Fujian Province, and the main line sectional switch tripped. At 17:15:12, the fault point was automatically isolated and normal power supply to users in the fault section was restored.

Such self-healing in just 24 seconds is supported by the application of the fully automatic FA function of the distribution network's dispatching automation system.

FA is the abbreviation of feeder automation. It refers to the use of automated devices or systems to monitor the operating status of the distribution network, promptly detect and accurately locate distribution line faults, automatically isolate the fault point and restore power supply to non-faulty sections within seconds. This technology effectively improves the intelligence level of the distribution network, facilitates fully automatic troubleshooting without awareness and enables the distribution network repair themselves. 

Operation and Maintenance Before Failure Improves Power Supply Reliability

On October 7, Chen Rui and Chen Zheliang, members of the distribution operation and inspection team of the Distribution Operation and Inspection Center of State Grid Putian Power Supply Company, are conducting routine inspections of the distribution station building. They discovered abnormal partial discharges in the 911 and 912 switch cabinets in the No. 1 distribution room of the 10 kV Yangxi resettlement power distribution station and immediately reported it to the "Defect Elimination Plan". By cleaning and replacing equipments such as wall bushings and insulators, they eliminate equipment defects, letting maintenance outrace faults. They avoided a possible trip caused by equipment failure and improved power supply reliability.

This is an example of State Grid Fujian Electric Power's effort to carry out the "maintenance before failure" campaign, promote "equipment owner responsibility", and prioritize "operation and maintenance and eliminate hidden dangers and defects" to ensure the safe and reliable operation of the distribution network.

In March this year, State Grid Fujian Electric Power launched a special campaign to "maintenance before failure" for distribution network equipment. By improving the equipment ownership and management supervision mechanism, it focuses on the quality of equipment operation and maintenance, management of problem equipment sales and fault management, establishes the equipment management concept of "maintenance before failure" and steadily improves the reliability of power supply and voltage qualification rate.

In the "equipment owner responsibility" system, the full-process management responsibilities of each distribution network equipment are detailed and assigned to specific operation and inspection personnel. State Grid Fujian Electric Power reasonably allocates operation and maintenance professionals as equipment owners based on the regional distribution of equipment, number of customers and other conditions. They focus on the management and control of the operating status of distribution network equipment, carry out monitoring of equipment operating status on a regular basis, and use the "i State Grid" APP to track fault inspections, emergency repairs, etc., and track the operation status of equipment in real time. As the hidden dangers and defects of the equipment are discovered and eliminated in time, healthy and stable operation of equipment can be guaranteed for a long time. In the first half of this year, the operation quality of Fujian's power grid has steadily improved and the average duration of power outage per household has dropped by 13.6% year-on-year.

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