Why do we need a grid with self-healing capabilities?

Why do we need a grid with self-healing capabilities?
--Recloser controller with 4G/5G communication as the cornerstone at its core
Driven by both energy transformation and digitalisation, the power grid is evolving from a traditional one-way power supply model to an intelligent, self-healing one. The recloser controller based on 4G/5G communication technology has become the core equipment for building a self-healing power grid by virtue of its ‘sensing-transmission-processing-decision-execution’ closed-loop capability. In this article, we will analyse its technical core and application value from five major layers.

Perception layer: real-time monitoring of the whole area, faults have no place to hide.
The perception layer of the recloser controller relies on high-precision sensors and intelligent terminal equipment to achieve millisecond-level collection of power grid parameters. For example, the ‘5G differential switch’ of Zhejiang Cixi Power Grid has built-in voltage/current sensors, which can monitor the running status of the line in real time and accurately capture abnormal signals such as instantaneous overcurrent and short circuit.
The 5G differential switch is equipped with a built-in voltage/current sensor, which can accurately capture abnormal signals such as instantaneous overcurrent and short circuit. Through the primary and secondary fusion technology, the equipment can not only obtain electrical data, but also combine the environmental temperature and humidity, equipment vibration and other auxiliary information to build a multi-dimensional fault warning model. This holographic sensing capability provides a reliable data foundation for subsequent fault location and isolation.

Transmission layer: 4G/5G dual-mode communication, low latency and high reliability
While traditional optical fibre deployment is costly and has a long cycle time, 4G/5G communication technology provides flexible and efficient transmission channels for recloser controllers through wireless network slicing and differentiated services. For example, the 5G intelligent distributed self-healing system is used in the distribution network of Huoning County, Yunnan Province, with a communication delay of less than 10 milliseconds, guaranteeing the synchronous transmission of differential protection signals
The ‘intelligent distributed self-healing system’ proposed in the patented technology. The ‘hierarchical communication architecture’ proposed in the patented technology further optimises the data transmission path, avoids the accumulation of delay caused by multilevel forwarding, and increases the speed of protection action to 2,426 times of the traditional mode. At the same time, the 4G/5G dual-mode redundancy design ensures communication reliability in extreme environments, and even if the local network is interrupted, core service operation can still be maintained through adaptive switching.

Processing Layer: Edge Intelligent Analysis, Second Fault Diagnosis
AI algorithms are embedded in local terminals to realise real-time data processing on the edge side. Taking Fujian Power Grid's three-tier self-healing system as an example, its recloser controller has a built-in deep learning model that combines historical data and real-time waveforms to distinguish between transient and permanent faults.
The recloser controller can combine historical data and real-time waveforms to distinguish between transient and permanent faults. Through the longitudinal current differential protection and directional protection algorithms, the fault location accuracy reaches the metre level, and the optimal isolation scheme is automatically generated. For example, when a short circuit is detected between the phases of a line, the controller can complete fault identification within 0.5 seconds and trigger the ‘differential protection + switch trip + reclosing’ linkage logic, avoiding the response delay of manual intervention.

Decision-making layer: dynamic topology reconfiguration, optimal load switching
The core of the self-healing grid lies in the autonomous decision-making capability. Based on 5G network slicing technology, the recloser controller can dynamically adjust the power supply topology to quickly restore power supply to non-fault areas. Taking the Xihe B838 line of the Cixi grid as an example, when a permanent fault occurs in the F1 section, the system automatically closes the contact switch (e.g., Xihe B8382) through priority determination, and transfers the loads to the neighbouring line, and the whole process from isolation to restoration of power supply takes only a few seconds.
The whole process takes only a few seconds from isolation to restoration of power supply. The ‘variable-rate interaction mechanism’ proposed in the patent document further optimises the decision-making efficiency: a low-rate heartbeat message is used under normal conditions, and the system switches to a high-speed data stream when a fault occurs, which not only reduces the traffic consumption, but also ensures the real-time nature of key commands.

Execution Layer: Precise Device Manipulation, Closed-loop Self-healing Verification
The execution layer relies on highly reliable switching mechanisms and closed-loop verification mechanisms to ensure that decision-making commands are accurately implemented. For example, the distribution automation master station in Xuchang, Henan Province, remotely operates circuit breakers via 5G network, achieving millisecond response for gate opening and closing operations.
The system is built-in to prevent the switch from refusing to move. In order to prevent switch refusal, the system has built-in failure protection logic: if a switch is detected as not executing a trip command, it immediately jumps adjacent switches and starts the standby link, such as in the case of Huaning County, where load transfer was completed within 4.83 seconds through the self-provisioning device. In addition, the controller verifies the execution effect in real time by comparing the magnetic signal feedback and current waveform, forming a complete closed loop of ‘sensing-action-checking’.

Conclusion: The future of self-healing power grid
With 4G/5G communication as the cornerstone, the recloser controller is promoting the transformation of power grid from ‘passive repair’ to ‘active defence’. By upgrading the whole level of intelligence, the fault processing time is compressed from hourly to secondly, and the user's perception of power outage tends to be close to zero. With the deep integration of 5G network slicing, edge computing and other technologies, the future power grid will realise larger-scale new energy access and autonomous operation in more complex scenarios, providing solid support for the ‘double carbon’ goal and the construction of the energy Internet.