5G has begun to be deployed commercially. In the early stages of 5G deployment, power consumption is a problem that all parties are trying to solve. For example, at the rail transit exhibition last month, the subway industry introduced that 5G base stations are currently being deployed in the subway line, and the power consumption of the single system of 5G pilot equipment is 2.5 times to 4 times compared with 4G, which has a greater impact on power equipment and supporting facilities, and it is necessary to add independent distribution cabinets to ensure power load balancing.
A few days ago, a material of the operator's analysis of 5G power supply showed that on the one hand, the power of 5G BBU is doubled compared to 4G equipment, on the other hand, the BBU centralized cabinet, that is, the CRAN cabinet, can be placed 5 to 10 BBU, the maximum power of a single cabinet is more than 10kV, power supply, heat dissipation are a great challenge.
Even if technological improvements such as RF module amplifiers are considered, the existing sites evolve to 5G, and the station power will be doubled.
The reconstruction of the communication room infrastructure, not only 5G CRAN, but also the transmission of OTN, the power of router equipment is multiplied, and the hybrid deployment of ICT equipment has also caused local hot spots, and the energy consumption is very large, which are the power supply and heat dissipation challenges of the computer room. The existing -48V DC power supply system has a small power supply radius and small capacity, which cannot meet the deployment of high-power density equipment.
Therefore, with the reconstruction of infrastructure in the 5G era, the power supply architecture also needs to be changed, and it can transition to mains power + backup power supply, with 220V mains as the mains.
5G base stations have three power supply schemes, one is CU/DU, AAU common base station power system; the other is CU/DU uses base station power supply system, AAU uses 5G intelligent power supply; third, CU/DU, AAU shared outdoor cabinet power system, which requires operators to build new outdoor cabinets with power supply and air conditioning.
Standardization is imperative
Due to the high bandwidth, high traffic and high transmission power of 5G networks, the energy consumption of its single station has increased sharply. And due to the increase in the power density and absolute value of energy consumption of individual devices, local hot spots have emerged. These problems pose serious challenges to traditional power supply systems and refrigeration. In this regard, the industry has proposed various solutions and products, which need to be further standardized and standardized.
Standardization bodies such as the International Telecommunication Union (ITU) and the China Communications Standardization Association (CCSA) have set up research to promote standardization work, and have jointly proposed a proposal for a sustainable power supply plan for 5G networks in the ITU jointly proposed by China, France Telecom and Huawei Technologies Co., Ltd. At CCSA, the China Academy of Information and Communications Technology took the lead in proposing a research project on "Research on Power Supply and Refrigeration Technology for 5G Base Stations".
ItU-T L.1210 "Sustainable Power Supply Scheme for 5G Networks" standard is jointly written by the Chinese Academy of Information and Communications Technology and Huawei. In China, it has also studied and formulated the China Communications Standardization Association (CCSA) SR287-2020 "Research on 5G Base Station Power Supply and Refrigeration Technology". Based on the above international standards and the research report of the Association, the Chinese Academy of Information and Communications Technology has made an overall layout for the 5G power supply and refrigeration field from the aspects of power supply, air conditioning, batteries, cabinets, etc., and together with operating enterprises and suppliers in the industry, the 5G power supply and environment infrastructure series of standards were proposed at the 35th plenary session of CCSA TC4 in December 2019, namely: "5G Power Supply and Environment Infrastructure Part 1 General Principles" and "5G Power Supply and Environment Infrastructure Part 2" Outdoor self-cooling blade power system", "5G power supply and environment infrastructure part 3 multi-input multiple output integrated energy cabinet" and "5G power supply and environment infrastructure part 4 indoor rack temperature control system".
In addition, the series of standards China has also planned some standards for boost power supply, some standards for energy storage systems, some standards for cabinet liquid cooling and standards for edge computer rooms, etc., and expand and adjust the content of this series of standards closely with the development and demands of the industry.
With the large-scale commercialization of 5G networks, 5G base stations and even supporting various types of computer rooms (including edge data centers) and data centers will gradually increase, so it will bring greater energy consumption challenges. From the perspective of equipment development and energy efficiency, it is recommended to use more efficient hardware modules and materials to further improve equipment efficiency from different levels of different equipment and different components contained in different disciplines. At the same time, it is recommended that operators actively promote the pilot demonstration and promotion and application of energy-saving technologies, and strive to improve the energy efficiency of various equipment and systems operating online. At the same time, industry, academia and research should work together to increase investment, promote research on more efficient network architecture, and further improve overall energy efficiency. In addition, priority will be given to the use of green energy and natural cooling sources, transforming energy use patterns, reducing environmental impact, and promoting green and sustainable development
Overall architecture and challenges of 5G networks
As we all know, the three major services of 5G mainly include enhanced capacity, access to massive terminals, and ultra-high reliability and ultra-low latency communication. Among them, enhanced mobile broadband can realize 3D/ultra-high-definition video, high-definition voice and cloud office; Ultra-high reliability and low latency communication enable industrial automation, autonomous driving, highly reliable applications, and mobile health.
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Figure 1: The three major services of 5G
According to Xiong Yong, the overall framework of the 5G network is mainly transmitted by UE, received by the site, and then transmitted to the three-level DC to achieve the construction of infrastructure such as computing, storage and networking.
Figure 2: The overall framework of the 5G network
Xiong Yong pointed out that higher frequency bands and increased data traffic have led to a surge in the number of sites. According to relevant statistics, the number of DC computer rooms, macro stations and Small Cell sites continues to grow, especially the Small Cell site. At the same time, the energy demand of 5G networks is also showing different directions. Among them, the number of DC computer rooms has increased, requiring more reliable and efficient power supply schemes; The power consumption of 5G base station equipment has increased significantly, providing more challenges for power supply; The Small Cell site has exploded, and its installation methods are mainly poles and wall mounts.
The overall framework of 5G network energy is mainly composed of three parts: DC computer room, macro station and independent AAU/micro station. The products and systems to which they are applied vary. The DC machine room mainly promotes the high voltage DC + mains direct supply scheme, which is reliable, efficient and low TCO, saving 40% of the investment in power supply equipment and up to 10% in electricity costs. Secondly, the main promotion site of the macro station is expanded, which benefits the old battery module and battery and saves investment; High-density and high-power embedded power supply + intelligent lithium battery is recommended to save space and improve efficiency. Independent AAU/micro-station mainly promotes PAD power supply & battery solution, self-cooling and heat dissipation to improve reliability, on the pole on the tower to reduce line loss and improve efficiency, intelligent power to save O&M costs.
Figure 3: Overall framework of 5G network energy
5G power supply solutions
Focusing on the core value of customers, that is, high reliability, low TCO, and achieving good and economical results, is the preferred choice of 5G power solutions. Efficiency, intelligence and smooth scaling have become the measures of the preferred solution for 5G power supplies. So, how can these three criteria be met?
Xiong Yong pointed out that high efficiency can be achieved by improving the efficiency of power conversion, reducing losses by high voltage power supply, thickening the wire diameter, shortening the power supply line, reducing line loss, and efficient maintenance to save manpower.
5G core computer room (central DC, regional DC) and large aggregation machine room can be applied. Mainstream manufacturers 5G core room equipment (servers, routing, switching, etc.) and aggregation room equipment (OTN, PTN, etc.) can support high-voltage DC power supply.
Figure 4: A 5G area DC machine room uses a high-voltage DC power supply field photo
Intelligent can achieve intelligent peak shifting, solve the shortage of mains power, and save investment. Through power supply monitoring, setting the mains capacity, using the battery balance power supply, and supplementing the mains power difference at peak time, it can not only reduce the transformation of the mains and save investment, but also save coordination time and achieve rapid 5G deployment.
For example, in guizhou's 5G power supply intelligent peak shaving test station, Guizhou Tower in view of the 5G high power consumption demand brought about by the problem of external mains transformation, from May to June 2019, selected two typical indoor and outdoor scenarios for power supply transformation, through the site power capacity expansion transformation, intelligent scheduling of intelligent peak shaving scheme, quickly and efficiently and low-cost solutions to the bottleneck problem of insufficient mains capacity of 5G sites, and finally calculated by outdoor sites, the overall transformation cost of intelligent peak shaving is only 1/4 of the cost of municipal power transformation, and the economic benefits are obvious.
Figure 5: 5G power supply intelligent peak shaving test station (Guizhou)
In addition, smart lithium batteries can realize intelligent boost, intelligent sharing and intelligent anti-theft; Intelligent monitoring to solve multi-energy, multi-service management, unified management and scheduling, maximize energy savings, save electricity bills, and achieve intelligent sharing, metering the electricity and electricity consumption ratio of each type of business, and can be set up for business power down on demand; Provide power on demand, power supply and AAU or wireless management background communication, real-time grasp of wireless equipment input voltage and power requirements, adjust the power supply voltage and power, reduce losses to achieve a state of intelligent collaboration.
Smooth expansion of power supply can protect existing investments and reduce the impact on the power supply of live grid equipment; Use battery sharing to achieve intelligent parallel use and protect existing batteries; Expand with power distribution to meet 5G demand.
Deploy 5G communication equipment on the existing physical sites of 2G/3G/4G networks and expand power supply facilities.
Figure 6: Key points of power supply expansion at common sites
The core principle of the 5G common site power supply scheme is to focus on the core value of customers, that is, saving (the lowest comprehensive cost), fast (the shortest transformation cycle), easy (the easiest to implement), and less (the least impact on the existing network).
Figure 7: Overall recommendations for power supply at common sites
At present, ZTE communication power supply mainly includes the core computer room, transmission room, data center power supply of large power supply, for the Hongji station power supply of indoor power supply, outdoor power supply, embedded power supply, as well as for micro-station and small capacity site power supply Pad power supply and wall mount power supply and other series. The following are some of the relevant power supply solutions provided by ZTE in the speech.
Figure 8: Indoor 600A power system common site scheme
Figure 9: Outdoor common station power supply scheme: New power supply system power supply
Figure 10: Power supply scheme for outdoor co-sites: Li old existing cabinets
5G power supply part of the product introduction
1. Central computer room
The central computer room is mainly powered by HVDC and 48VDC. Among them, HVDC is the development trend of power supply, which mainly depends on the requirements of the main equipment in the DC machine room for power supply. ZTE discrete power supply ZXDU88 S402 is widely used in domestic mobile, telecom and Unicom, shipping more than 1,000 sets per year.
Figure 11: ZTE Discrete Power Supply ZXDU88 S402
2. Outdoor microstation / Independent AAU (RRU)
Outdoor micro-station/independent AAU (RRU) scenarios are typically used in urban light pole stations, roof macro stations, Layuan stations, AAU decentralized deployment, high-speed railways, highways and tunnel stations. The core values of the PadPower solution are as follows.
All outdoor: zero footprint, more flexible, fast and low-cost deployment;
Full self-cooling: higher reliability, higher product efficiency;
Full efficiency: the system efficiency can reach 97%, the power supply system is closer to the power equipment, and the line loss is less;
Smarter: No commissioning, no maintenance, rapid deployment, saving O&M costs.
3. Battery: Smart lithium battery
Intelligent lithium battery with power supply system, constant output of 57VDC voltage, improve the distance; The same distance can reduce the line loss, but also can be directly mixed with the live network battery, protecting the existing investment.
Intelligent parallel connection does not require external coupling, higher reliability, lower investment cost, and the mixing of new and old lithium batteries supports batch investment and saves initial investment. In addition, the smart lithium battery can only be automatically locked offline (stolen) to be authorized to unlock, and can also be built-in GPS tracking to determine the location of the battery. Therefore, intelligent lithium batteries can achieve intelligent boost, intelligent mixing and intelligent anti-theft at the same time.
Figure 12: Smart lithium batteries
First, UPS uninterruptible power supply - continuous electric cutting process
In power cutting, for dual power supply equipment, the power cutting method can be adopted; However, when encountering a single-power supply device, and the equipment is very important, it is not allowed to interrupt the cutting, and it is often necessary to use an uninterruptible electrical cutting process.
UPS Uninterruptible Power Supply – Continuous electrical cutover
Reference steps:
1. New UPS new system, new system debugging and battery capacity test completed.
2. Arrange the temporary cable, from the new UPS output screen to the power front table to be cut and the old input screen bypass switch, after confirming that there is no error, the cable is transmitted.
3. After testing the normal power supply, turn off the inverter of the old UPS system and confirm that the old UPS is working in the bypass mode, at this time, the power supply of the old UPS system and the power supply of the new UPS system are homologous (the output is from the new UPS system).
4. Close the output of the new UPS main road, test the front cabinet main circuit backup empty open upper and lower end voltage, carry out nuclear phase operation (measure the voltage difference between the upper and lower pile heads of the main side standby switch, the principle is less than 1V), after confirmation, you can first close the main side standby switch, confirm the current, and then break the main side main switch.
5. Remove the main road cable from the old UPS to the head cabinet.
6. Same method, cut the standby power supply.
7. After the cut-off is completed, the temporary cable and the old cable are removed.
8. Do a good job of marking the air opening and cable.
Note: Considering the different battery configurations between different UPS systems, considering the short battery update cycle in the UPS system, under normal circumstances, UPS updates are synchronized with battery updates, so the battery cutting steps are generally not considered in the UPS cutover process.
Second, the basic principle of cut-off
1. The principle of unimpeded network security
The online power system cut-off project must ensure the safe operation of the network equipment and the smooth flow of the entire network, and any operation that endangers the network security must be terminated unconditionally.
2. The principle of no failure of the equipment
Before and during the implementation of the online power system cut-off project, the new and old equipment must be guaranteed to be intact, and if any factors that may endanger the safe supply of power occur, they must be unconditionally terminated and can only continue until troubleshooting.
3. Low business risk principle
Under the premise that the service does not allow the interruption of power supply, the online uninterrupted power cut-off scheme should be adopted, otherwise the power-off cut-off scheme should be adopted;
The engineering cut-off time should avoid the peak of the business, and the major cut-off arrangement should be carried out at night;
The date of the project cutover should avoid the time of network adjustment and version upgrade for major holidays, major communication support tasks and other professional arrangements;
4. The principle of qualified construction personnel qualifications
Engineers implementing online power system cut-off engineering must be proficient in power equipment operation and engineering construction operations, familiar with the communication power system cutting process, and keep in mind the emergency plan.
The construction team that implements the cut-off must have a construction certificate with the corresponding project level qualification;
5. Maintain the principle of supervision of the whole process of the department
The maintenance department shall arrange special personnel to supervise the whole process during the cutting process, assist in the design survey of the cutting project, review the cutting plan and emergency plan, and supervise the implementation of the cutting.
6. Maintain the principle of "one-vote veto" of the department
During the cut-off project, the maintenance department has the right to exercise a "one-vote veto" on the cut-off work and terminate the cut-off project for major program defects and major construction safety hazards found.
Third, UPS uninterruptible power supply cut-off preparation
1. The new UPS system completes the boot debugging, the battery full capacity test, and the monitoring is in place.
2. Arrange the cable in advance and paste the standard cable label; When a temporary cable is required, the appropriate wire diameter must be selected, reliably connected, and clearly marked
3. According to the wiring position of the original power equipment cable, write the cable number mark to ensure that the cable disassembly process will not be confused.
4. Confirm that all dual power supply device main standby power modules are working normally, and the main standby power supply is separated.
5. Announce the cutting project in advance.
6. Confirm that the relevant majors have made data backups for related businesses and have prepared emergency plans.
7. Fire fighting equipment and safety rescue equipment are in place.
8. Wear and use personal protective equipment correctly, do not carry any metal objects and remove accessories that may lead to insecurity (watches, work badges worn around the neck, etc.).