In-depth Analysis of Intelligent Solutions for the Distribution Automation Industry: Network Equipment Selection and Deployment Strategies

Introduction: Core Challenges in Distribution Automation Upgrades
Distribution automation is a critical component in constructing new-type power systems, with its level of intelligence directly impacting the reliability, economy, and environmental friendliness of the power grid. According to State Grid statistics, communication interruptions account for 37% of misoperations/rejections in faults on 10kV and above distribution lines in China, with traditional deployment methods presenting three major pain points:

• Fragmented communication protocols: Coexistence of multiple protocols such as IEC 61850, DNP3, and Modbus complicates device interoperability.
• Poor environmental adaptability: Outdoor cabinets experience significant temperature and humidity fluctuations (-40℃~75℃), with ordinary devices suffering a failure rate as high as 23% per year.
• Insufficient business isolation: Mixed transmission of control commands and monitoring data leads to key business delay fluctuations exceeding ±50ms.
  This solution delves into typical scenarios of distribution automation, thoroughly analyzing the selection logic for three types of equipment—industrial switches, 5G cellular routers, and 4G LTE cellular modems. Combining practices from the "Three Types, Two Networks" construction of a provincial power grid, it proposes an intelligent deployment strategy of "protocol unification + environmental adaptation + business stratification."

1. Evolution Trends in Distribution Automation Network Architecture
   1.1 Functional Upgrades from "Three Remotes" to "Six Remotes"
   Traditional distribution automation achieves telemetering, telesignaling, and telecontrol (three remotes) functions, while next-generation systems introduce additional capabilities: tele-adjustment, tele-vision, and tele-pulse (six remotes). This requires network equipment to feature:

• High bandwidth capacity: A single 4G LTE cellular modem must simultaneously transmit video from 16 cameras (approximately 16Mbps).
• Low latency guarantees: Differential protection services demand end-to-end latency of less than 12ms.
• High-precision synchronization: PMU devices must meet the IEEE 1588v2 protocol, with time synchronization errors below 1μs.
  1.2 Standardization Process of Communication Protocols
  The State Grid's "Technical Specifications for Communication Protocols between Main Stations and Terminals in Distribution Automation Systems" stipulates:
• Main station-terminal: Prioritize the use of IEC 60870-5-104 or DL/T 634.5104 protocols.
• Terminal-device: Support protocol conversions such as Modbus TCP and IEC 61850-90-5.
• New services: 5G networks must support TSN (Time-Sensitive Networking) extensions.
  1.3 Typical Deployment Architecture
  [Cloud Platform]
  │
  [5G Core Network/SDH Dedicated Line]
  │
  [Regional Centralized Control Station] ←─Industrial Switch Ring Network─→ [10kV Switching Station]
  │ │
  [5G Cellular Router] [4G LTE Cellular Modem + Industrial Switch]
  │ │
  [Mobile Inspection Terminal] [FTU/4G LTE Cellular Modem/Fault Indicator]

1. Core Equipment Selection Methodology
   2.1 Industrial Switches: The Foundation of High-Reliability Ring Networks
   Applicable Scenarios:

• Dense deployment at fixed points: Interconnection of devices within switching stations and ring main units.
• Deterministic transmission of high bandwidth: Carrying high-traffic services such as video surveillance and PMU data.
• Protocol conversion requirements: Implementing functions like Modbus RTU to TCP and IEC 101 to 104 conversions.
  Selection Criteria:
• Ring network protocol support: Prioritize devices supporting the ERPS (ITU-T G.8032) protocol, with fault self-healing times under 20ms. Field tests by a municipal power supply company revealed that USR-ISG series switches achieved a 99.999% success rate in link switching within intersecting ring topologies.
• Environmental adaptability: Choose products with an IP40 protection rating and a wide temperature range of -40℃~75℃. The USR-ISG-24GT switch deployed in the Qinghai Plateau region operated fault-free for three consecutive years.
• Clock synchronization capabilities: Equipped with IEEE 1588v2/PTP functionality to meet differential protection synchronization needs. Test data indicates that this feature reduces protection action time errors from ±5ms to ±0.5ms.
  2.2 5G Cellular Routers: Intelligent Conduits for Mobile Services
  Applicable Scenarios:
• Mobile inspections: Dynamic access for insulated bucket trucks, robotic inspections, etc.
• Emergency communications: Temporary repairs when natural disasters disrupt optical fibers.
• Coverage in remote areas: Regions like mountains and grasslands where wired network deployment costs are prohibitive.
  Selection Criteria:
• Dual-link hot standby: Support for 5G/4G + wired WAN dual links, with packet loss rates during primary-backup link switching below 0.1%. During typhoon emergency responses, the USR-G816 router ensured real-time monitoring of distribution terminals in disaster areas.
• Edge computing capabilities: Built-in Python runtime environment for local processing of emergencies such as temperature overruns and switch position changes. Applications in a chemical plant demonstrated a 75% reduction in fault reporting latency through edge processing.
• Precise positioning functionality: Integrated Beidou/GPS dual-mode positioning with accuracy below 1 meter. In scenarios preventing external damage to distribution lines, this feature reduced false alarm rates by 90%.
  2.3 4G LTE Cellular Modems: Cost-Effective Terminal Access Solutions
  Applicable Scenarios:
• Legacy device retrofits: Networking upgrades for serial communication legacy devices.
• Low-bandwidth services: Transmission of small data volumes such as electrical energy collection and switch status monitoring.
• Cost-sensitive projects: Scenarios with limited budgets requiring basic "three remotes" functionality.
  Selection Criteria:
• Multi-protocol adaptation: Support for RS232/485 to TCP/UDP conversions, compatible with protocols like IEC 101 and DNP3. The USR-G771 4G LTE cellular modem seamlessly integrated 32 devices from different manufacturers during a cement plant retrofit.
• Link maintenance technology: Utilizes heartbeat packets + reconnection mechanisms to ensure stable communication in weak network environments. Deployment tests in subway tunnels improved data integrity rates from 82% to 99.9%.
• Simplified configuration tools: Provides visual configuration via mobile apps/web interfaces, reducing on-site debugging difficulty. Power construction teams reported a 60% reduction in configuration time for the USR-G771 compared to traditional 4G LTE cellular modems.

1. Typical Scenario Deployment Solutions
   3.1 Urban Distribution Network Automation Retrofits
   Demand Analysis:

• High density of switching stations (average spacing <1km).
• Need to carry multiple services such as video surveillance and PMU.
• Requires communication latency below 15ms and availability exceeding 99.999%.
  Solution:
• Backbone ring network: Construct a dual-fiber ring network using USR-ISG-16GT switches, with core nodes configured with two 10G optical ports.
• Access layer: Deploy one USR-ISG-8GT per switching station, implementing link redundancy via the ERPS protocol.
• Business isolation: Establish VLAN 10 (control services), VLAN 20 (video services), and VLAN 30 (monitoring services).
  Implementation Results:
• In a pilot project in a new district, network latency decreased from 32ms to 9ms.
• Annual fault occurrences dropped from 4.7 to 0.2.
• Video surveillance stuttering rates decreased from 18% to 0.5%.
  3.2 Centralized Control Systems for New Energy Stations
  Demand Analysis:
• Wide distribution of distributed photovoltaic/wind power equipment (radius >10km).
• Need to transmit small volumes of information such as inverter status and meteorological data.
• Lack of optical fiber coverage in some areas, requiring wireless backup.
  Solution:
• Wired section: Construct a star network within the station using USR-ISG-8GT switches.
• Wireless section: Equip each inverter with a USR-G771 4G LTE cellular modem for data backhaul via 4G networks.
• Backup links: Deploy USR-G816 routers at critical nodes, configured with 5G + wired dual links.
  Implementation Results:
• Field tests at a photovoltaic power station revealed automatic switching times for wireless backup links under 3 seconds during optical fiber interruptions.
• Data collection integrity rates improved from 92% to 99.97%.
• Annual operation and maintenance costs decreased by 65%.
  3.3 Emergency Repair Communication Support
  Demand Analysis:
• Need to rapidly establish temporary communication networks.
• Support concurrent voice, video, and data services.
• Equipment must be portable and easy to deploy.
  Solution:
• Main station side: Deploy USR-G816 routers as 5G CPE, providing Wi-Fi 6 hotspots.
• Field side: Connect portable monitoring terminals using USR-G771 4G LTE cellular modems.
• Security enhancement: Enable IPSec VPN to ensure secure data transmission.
  Implementation Results:
• During a typhoon emergency response, a communication network was established within 30 minutes.
• Video conference clarity reached 1080P@30fps.
• Repair instruction delivery latency decreased from 15 minutes to 2 minutes.

1. Equipment Selection Decision Matrix
   | Evaluation Dimension | Industrial Switch | 5G Cellular Router | 4G LTE Cellular Modem |
   | --- | --- | --- | --- |
   | Transmission Bandwidth | 100Mbps-10Gbps | 100Mbps-2Gbps (5G) | <2Mbps |
   | Deployment Cost | Medium-High (fiber + equipment) | High (5G service fees + equipment) | Low (equipment cost only) |
   | Mobility Support | Fixed deployment | Supports high-speed mobility (>120km/h) | Fixed deployment |
   | Latency Performance | <1ms (deterministic latency) | <20ms (5G URLLC scenarios) | <100ms |
   | Typical Applications | Switching station ring networks, video surveillance | Mobile inspections, emergency communications | Legacy device retrofits, electrical energy collection |
   Decision Recommendations:

• Fiber-accessible areas: Prioritize industrial switches for ring network construction, offering the best cost-benefit ratio.
• Dynamic access scenarios: 5G cellular routers are essential, such as for insulated bucket truck inspections.
• Budget-limited retrofits: 4G LTE cellular modems represent the most economical choice for networking legacy devices.
• Hybrid networking requirements: Adopt an architecture combining "switches as the backbone + routers as backup + 4G LTE cellular modems as supplements."

1. Technological Evolution Directions
   5.1 5G LAN Deterministic Networking
   The 5G LAN functionality defined in the 3GPP R17 standard enables end-to-end latency below 10ms, meeting stringent demands such as differential protection. A pilot project demonstrated that 5G LAN reduced communication costs for distribution terminals by 40% and decreased latency fluctuations from ±15ms to ±2ms.
   5.2 TSN Time-Sensitive Networking
   The TSN technology defined in the IEEE 802.1Qcc standard achieves microsecond-level latency guarantees through time-aware shapers (TAS). Subsequent versions of the USR-ISG series switches will integrate TSN functionality, providing more precise synchronization control for new energy grid connections.
   5.3 AI-Powered Operation and Maintenance Automation
   Machine learning-based network self-healing systems can predict optical fiber attenuation trends and automatically optimize routing paths. A pilot project by a provincial power grid revealed that AI operation and maintenance reduced unplanned downtime by 78% and improved operation and maintenance efficiency fivefold.

Conclusion: Building a "Self-Healing, Self-Optimizing, Self-Intelligent" Distribution Communication Network
The essence of intelligent upgrades in distribution automation lies in constructing a communication network with self-awareness, self-decision-making, and self-execution capabilities. Industrial switches, 5G cellular routers, and 4G LTE cellular modems are not mutually exclusive but rather form a complementary ecosystem:

• Industrial switches lay the foundation for high-reliability ring networks.
• 5G cellular routers expand the boundaries of mobile services.
• 4G LTE cellular modems activate the value of legacy devices.
  In practical deployments, the basic principle of "using switches for core ring networks, selecting routers for dynamic access, and equipping legacy systems with 4G LTE cellular modems" should be followed, with comprehensive decision-making based on business priorities, cost budgets, and environmental conditions. As technologies like 5G LAN and TSN mature, distribution communication networks will evolve toward full-service deterministic transmission, providing a more robust digital foundation for constructing new-type power systems.