5G Network Slicing for Smart Grid

Since it was launched in 2001, smart grid has been widely recognized in the industry. Governments, power enterprises, and scientific research institutions in various countries have conducted in-depth research and practical exploration based on their respective economic and social development levels, energy characteristics, and power industry development phases.

Service scenarios of smart grid  

Smart grid covers five key links: power generation, power transmission, power transformation, power distribution, and power consumption. Dozens of smart grid communication services need to be deployed in each link, and the requirements of services for SLA, such as latency, bandwidth, and security isolation, are greatly different. In accordance with the functions of grid services and security isolation requirements, grid services are divided into two types: production control region and management information region. The production control zone is divided into Safety Zone I and Safety Zone II. The services in the Safety Zone I are directly used to monitor the power system in real time, while the services in the Safety Zone II are only used to detect the power system without controlling. The management information zones are divided into Management Zone III and Management Zone IV/V, which mainly manage the power production and power grid enterprises, such as video monitoring and information-based office.

  Table 1 Typical Services of Smart Grid  

5G network slicing + smart grid  

The 5G+ smart grid applications involve safe and reliable operation of power grid, so it is different from the public network applications and it has strict requirements for security isolation and SLA guarantee. The smart grid services are widely used in various scenarios, including status awareness, control protection, data collection, AI assistance, and robot preventive maintenance. Various types of transmission data, including status data, control instructions, images, and videos, have different requirements for network bandwidth, latency, jitter, bit error rate, and reliability.

5G network slicing can be divided into multiple end-to-end logical networks on the basis of a unified physical network to meet the application scenarios with high bandwidth, high security, low latency, and ultra-high reliability of the grid and provide the best solution for smart grid communications. Smart grid slices can be designed based on the following dimensions or principles:

• Requirements for security isolation

In power grid, the services between the production area and management area need to be physically isolated, and the services in the production area or management area need to be logically isolated. Physical isolation means that different services are hard isolated. For example, wireless services use PRB resources reserved or independent spectrum, transmission services use different FlexE technologies, and core network uses independent servers. Logical isolation means that soft isolation technologies such as QoS, VPN, and VM are used between services.

Therefore, grid can be deployed with four types of slices to carry grid services in different areas.

1. The slicing between the production area and the management area uses the physical isolation technology to meet the high security isolation requirements of services in production areas.
2. In the production area, the soft isolation technology is used only when two slices are deployed to achieve logical isolation between area 1 and area 2.
3. In the management area, the requirement for security isolation between area III, area IV and area V is not high, so you can set up only one slice for isolation through QoS + DNN.
4. For local closed-loop services of the power grid, such as substations and small water plants, an LAN slice can be deployed.

Figure 1 Division of Smart Grid Slices

With respect to U-plane NEs, for the slicing in the production area where U-plane NEs need physical isolation, the independent dedicated U-plane can be deployed in the core network, independent FlexE channels can be established for transmission, and isolation modes such as resource reservation can be used in wireless network. The soft slicing technology can be used for slices that need logical isolation, such as slices between production area I and production area II. Core network may use shared UPFs, such as Slice 3 and Slice 4. Independent VLANs, independent address pools, bandwidth or user quantity admission control may be used between slices. The VPN technology may be used for bearing. Wireless network may use slice + 5QI for priority scheduling.

For the NEs on the C-plane, you can select whether to share or exclusively use them in accordance with the requirements of grid industry users and the operator's network construction principles. In most cases, customers require independent C-plane NEs while operators expect to share them with existing 2B NEs. According to the analysis, the grid service is mostly to isolate media plane data. Therefore, the C-plane can adopt the compromise solution. The grid exclusively occupies some C-plane NEs such as SMF, while UDM/PCF and AMF are shared with other 2B industries.

• Requirements for low latency and high bandwidth

For the grid services with low requirements for latency, such as differential protection, UPF can also be deployed to the edge DC, load bearing uses the FlexE high-speed forwarding channel, and wireless uses the URLLC technology. For grid services with low latency requirements, such as those in the management area, the slice type is eMBB, and the UPFs are deployed in the provincial capital center or the municipal DC in a centralized manner.

• Requirements for operation and management 

With open capabilities and more efficient and flexible operation and management capabilities, 5G slicing network can achieve visible, manageable and controllable grid services. Power enterprises can use the slicing capability exposing interfaces provided by operators to implement fast online commissioning (minute-level) of slices or new services. The slicing operation monitoring capability can be used to implement real-time monitoring of network resources and fault location. Through the subscription interface, online management of terminals can be implemented, and finally the visualization, management, and control of smart grids can be provided.

ZTE facilitates industry customers to construct a 5G+ smart grid

ZTE has made in-depth cooperation with power enterprises to provide a complete set of products such as wireless, bearer, convergent core network (5G Common Core) and slice management (CloudStudio GSO). It constructs end-to-end 5G network slicing with high security and isolation, and provides differentiated SLA guarantee for power grid services in different security areas to meet the requirements of high security, low latency and high reliability of the power grid. Secondly, ZTE provides a variety of solutions with key technologies, such as slicing capability exposing, 5G LAN, TSN, uRLLC, mMTC, precision timing, and small-granularity FlexE, to facilitate the rapid development and deployment of new services in 5G+ smart grid.