The application of substations with different voltages
Substations of different voltage levels constitute the backbone network of the power system. From ultra-high voltage transmission to terminal distribution, each level undertakes crucial tasks of electric energy conversion and distribution. Their application scenarios and technological innovations directly determine the efficiency and reliability of the power grid.
- Core application scenarios of voltage levels
- Ultra-high voltage (≥1000kV)
It is used for cross-regional and ultra-long-distance power transmission, facilitating the connection between energy bases (such as hydropower and wind power) and load centers. For example, the converter station in the Baihetan-Zhejiang UHV project reduces long-distance transmission losses through voltage boosting and utilizes a digital platform to enhance operation and maintenance efficiency.
Representative project: The 1000kV UHV substation supports the national "West-East Electricity Transmission" project, with a transmission distance of up to 1500 kilometers or more.
- Extra-high voltage (330kV-750kV)
As a regional power grid hub, it undertakes inter-provincial power allocation and backbone grid functions. For example, the 500kV Kebi Substation (the first near-zero energy consumption substation in China) integrates photovoltaic power generation, 3D printing, and other technologies to optimize energy consumption.
Expanding the main transformer in load-intensive areas (such as Chengdu 500kV Guangdu Substation) can alleviate the pressure of power supply during peak hours.
- High voltage (110kV-220kV)
Urban core power supply nodes: 220kV substations (such as Yanglin Substation in Jiangjin, Chongqing) directly supply power to industrial zones and urban centers. Upgrading the main transformers can enhance the reliability of regional power supply.
Terminal hub function: The 110kV substation (such as Changge Ducun Substation) has undergone GIS equipment renovation to optimize sealing performance, ensuring stable electricity supply for industrial users.
Distribution core level: 10kV lines cover more than 90% of the distribution network, providing direct power supply to residential areas, industrial and commercial areas. For example, the loop closing operation of 10kV lines in Mulan County achieves seamless load switching and "zero power outage perception" for users.
New energy adaptation: The 35kV substation can provide an interface for grid-connected distributed photovoltaic systems, and the installation of reactive power compensation devices (such as the mobile capacitor bank in Zhanjiang) can address voltage fluctuation issues.
- Low voltage (≤1kV)
Terminal household conversion: The distribution transformer converts 10kV/380V to 220V for residential use, hidden within residential areas or charging heads, ensuring safe power supply for the "last mile".
- Technological evolution and special scenario applications
- Solid-state transformer (SST) innovation
Traditional power frequency transformers (such as 10-ton steel-core equipment for ships) are transitioning to silicon carbide (SiC) high-frequency solid-state transformers. The Ford-class aircraft carrier adopts a 13.8kV solid-state substation, reducing its volume by 70% and supporting a medium-voltage DC power distribution system. AI data centers are driving the commercialization of SSTs, which adapt to fluctuating loads through high-frequency power electronics conversion. The market size is expected to exceed 13 billion yuan by 2030.
- Intelligentization and security upgrade
- Digital Twin Technology: Fujian 500kV Rongcheng Substation creates a "digital twin" of its equipment to monitor real-time account books and operation and maintenance data.
- Unmanned operation: Zhejiang Jiaxing Power Supply Company has applied live-line operation robots to replace manual high-voltage switching, resulting in an 85% increase in efficiency.
- Lightning protection: The lightning arrester achieves nonlinear pressure relief through a zinc oxide-based resistor disc, withstanding lightning strikes of millions of volts.
3. Future challenges and development directions
- New energy adaptation: The high proportion of new energy grid integration leads to bidirectional voltage fluctuations, requiring the deployment of distributed capacitors (such as the Lishui Forest Farm project) to stabilize power distribution.
- High-density power supply: AI computing power clusters attempt to build micro data centers next to substations, utilizing the surplus capacity of the power grid for dynamic load scheduling (such as the NVIDIA pilot project).
- Low-carbon transformation: The 110kV "zero-carbon substation" in Wuxi, Jiangsu, integrates clean energy technologies to promote emission reduction across all aspects of the power grid.
Substations of different voltage levels are transitioning from passive power transmission to active regulation and control through technological iteration and scenario adaptation, becoming the core hub of the new power system.
