OSU Builds an All-Optical Base to Enable a New Power System

Yuan Daochun

Chief Architect of Huawei Government and Enterprise Optical Power Industry

With the development of electric power, the proportion of energy that comes from new energy sources increases steadily. The structure and operation characteristics of power grids change from the traditional single network for power generation, transmission, transformation, and distribution to the mesh network where multiple power grids coexist. Meanwhile, the roles of the power generation side, power supply side, and load side change dynamically: from the real-time balance mode in which the source follows the load to the source-grid-load-storage integration mode. These changes require a large amount of real-time data for precise prediction, as well as a robust scheduling system.

The development trend of power grids also places requirements on power communication networks, such as high bandwidth, high reliability, easy evolution, easy O&M, and long-distance communication. In terms of bandwidth, the introduction of a large number of sensing terminals invariably leads to bandwidth growth. In terms of reliability, the new power communication network must follow the principles of "horizontal isolation, vertical authentication, secure partitioning, and network for dedicated use" to ensure service system security and carry core power production systems such as relay protection. Besides this, the latency must be within the system design scope. In terms of evolution, the new power communication network must be compatible with the technology system of the existing power communication network, in order to ensure smooth evolution. Regarding O&M, the new power communication network must adopt the same O&M habits as the existing networks, so as to reduce training costs. When it comes to the transmission distance, the new power communication network must support ultra-long-haul transmission, because power grids always have ultra-long single spans. Therefore, the development of power grids requires a solid power communication network as the base for information transmission, ultimately supporting the digital transformation of the power industry.

Traditional power communication networks are classified into power transmission and transformation communication networks and power distribution communication networks, depending on the services they carry and the sites where they are deployed. Power transmission and transformation communication networks are classified into SDH network A and OTN network B. SDH network A mainly carries production control services. The downside of such a network is that, due to the limitation of the SDH industry chain, its maximum upstream bandwidth is 10 Gbit/s, failing to respond to the continuous bandwidth growth. OTN network B, on the other hand, mainly carries management information services and provides high bandwidth. However, due to its high network layer, OTN network B is usually deployed on the national backbone network, provincial backbone network, and some municipal backbone networks, and does not effectively cover substations, power supply stations, and service centers. The power distribution communication network uses the EPON and Ethernet switching architecture, and supports only power distribution automation services. On such a network, the value of optical fibers cannot be fully gleaned, and the network bearing efficiency is low.

F5G optical communication, as the fundamental communication technology, has become the base underpinning digital transformation of various industries. Based on OSU technology, the F5G optical communication network incorporates TDM hard pipe technology and offers service access capabilities ranging from 2 Mbit/s to over 100 Gbit/s. On top of that, it boasts 450 km ultra-long single-span transmission, making it the ideal communication infrastructure for electric power production services and supporting the digital transformation of the power industry.

To address the challenges of the new power system, OSU is designed with the following distinctive features:

• High bandwidth: SDH supports small-granularity services, with a maximum bandwidth of 10 Gbit/s, while OTN provides transmission capabilities of 10+ Gbit/s or even 96 Tbit/s. However, the minimum granularity for OTN is 1.25 Gbit/s, making it unsuitable to carry small-granularity electric power services. The OSU technology inherits the hard pipe characteristics of SDH and OTN, enabling it to support small-granularity services of SDH while providing the high bandwidth of OTN. It surpasses the 10G bandwidth limit of SDH and allows for flexible service access rates ranging from 2 Mbit/s to 100 Gbit/s or higher. This makes it well-equipped to handle the challenges posed by the rapid growth of new power device sensing and video information.

• Easy evolution: New devices support PDH/SDH/OTN services, and the new power communication network supports bandwidth upgrade to 100G+, as well as 100% smooth service evolution.

• Easy O&M: The OSU technology supports hitless adjustment from 2 Mbit/s to 100 Gbit/s, improving service deployment efficiency by 60%. OSU remains the original O&M habits of PDH/SDH.

Currently, OSU is widely recognized by standards organizations and industry organizations, including operators, industry customers such as electric power customers, component and chip vendors, and device vendors. Regarding standardization, OSU standards have been recognized by all major standards organizations as the next-generation standards, with many vendors following the standards. Additionally, OSU standards have achieved significant breakthroughs, with IEEE releasing its own set of OSU standards.

The OSU-based electric power communication network enriches electric power application scenarios in terms of end-to-end networking and O&M, and implements full-service bearing.

• DCI: ADSS/Buried optical cables are usually used in main cities, which are not affected by SOP. OSU-based 200G/400G OTN high bandwidth can be used to provide efficient transmission channels between data centers. In addition, DCI in urban areas is usually interconnected with branches over short distances, but there are many connection directions. OXC devices can be deployed for optical wavelength switching to implement fast service deployment and flexible wavelength grooming.

• Backbone OTN: connects the headquarters, branches, and second aggregation nodes. Optical cables are usually optical ground wires (OPGWs), which are highly affected by the natural environment. Especially in thunderstorms, OPGW induced electromagnetic fields will cause optical polarization rotation, affecting transmission performance. The OSU-based backbone OTN 100G 8 Mrad/s SOP technology is mature and has been commercially deployed. It meets the deployment environment of OPGWs and the large-capacity connection requirements of electric power companies, branches, and second aggregation nodes. For the 10G transmission system deployed in the early stage, the wavelengths in the system are consumed rapidly due to the continuous increase of bandwidth. To solve the problem that the wavelengths in the system cannot be increased in the future, the 100G + 10G hybrid transmission solution is provided to support smooth system expansion.

• Substation OTN: mainly solves the WAN interconnection problem between substations. The main services include production and office services. The OSU-based OTN 100G gray light direct connection mode can be used to implement optical layer–free and simplified networking. In addition, SDH-like timeslots are supported to provide highly reliable and end-to-end hard pipe connections.

• CPE OTN: For tail sites such as service centers, power supply stations, and PV power plants, OSU CPEs (AC power, small, and plug-and-play) can be used for OTN networking.

In addition, for the power distribution communication network, GPON can replace EPON, and OSU can replace ETH to implement physical isolation and multi-service bearing over one network. In this way, the power distribution communication network can collaborate with the power transmission and transformation communication network for end-to-end management and maintenance of power distribution automation services.

In the evolution to the target power network, network A inherits the SDH network construction mode (VC+OSU mode), ensures key production services are carried through hard pipes, and surpasses the 10G bandwidth limit of SDH. In the future, it will be able to better support device sensing and video data burst of the next-generation centralized control station. For network B, the large-capacity OSU-based OTN network can cover more substations or even service centers, providing high bandwidth for the entire network. Alternatively, based on the characteristics of OSU, the SDH network A can gradually evolve to OSU, and the OSU-based OTN network B can extend to 35 kV substations/service centers, achieving mutual backup between networks A and B.

In a word, the OSU-based OTN network uses the TDM technology and timeslot slicing to physically isolate services at a rate ranging from 2 Mbit/s to 100 Gbit/s. In addition, it provides end-to-end hard pipes to ensure service security and 100+ Gbit/s bandwidth, supports continuous evolution to the target power network, and has the same O&M habits as the SDH network, helping the power industry build a secure, stable, reliable, and easy-to-evolve all-optical communication base and enable new power systems.

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