What Are the Standard Substation Voltage Levels in China?
China’s power network uses several voltage tiers, each designed for a different distance and load. substation voltage levels help explain how electricity moves from large generating stations to factories, towns, and homes. A transmission substation may handle 500 kV or 750 kV, while regional networks commonly use 220 kV or 110 kV. Lower-voltage substations, often at 35 kV or 10 kV, supply local distribution systems. These figures describe nominal system voltages, not necessarily the exact readings seen on every instrument.
The full picture is more varied. Some areas use 66 kV networks, and major transmission corridors may operate at 1,000 kV AC. China also uses high-voltage direct-current links, including ±500 kV and ±800 kV schemes; these are not interchangeable with AC voltage labels. Important distinctions. Transformer nameplates, grid planning documents, and equipment specifications can show different voltage values because rated equipment voltage may differ from the network’s nominal level. Regional demand, terrain, and the connection point also shape a project’s design.
This overview introduces the common levels and their roles, rather than treating one list as universal. Standards and project requirements can change, so engineers verify the applicable national standards and local grid-company documents before selecting equipment. A chart is useful, but it cannot replace that check. Even a simple 110/10 kV substation involves protection settings, insulation coordination, and site conditions that deserve careful review. The labels look tidy; real systems are less tidy.
China’s Power Grid Structure and Substation Voltage Classes
What Are the Standard Substation Voltage Levels in China?
China’s power grid links generating stations to consumers through several voltage tiers. Large power plants feed high-voltage transmission networks, which carry electricity across long distances. Regional substations then lower voltage for cities, factories, and local distribution. The structure is layered. It is not uniform.
Common AC substation classes include 1,000 kV, 500 kV, 220 kV, 110 kV, 35 kV, and 10 kV. The 1,000 kV and 500 kV levels support bulk transmission, while 220 kV and 110 kV commonly serve regional networks. Lower levels connect industrial users and distribution systems. Some areas also use 66 kV, but it is not a standard choice everywhere. China also operates high-voltage DC links, including ±800 kV projects; these should not be confused with AC substation voltage classes. Actual configurations vary with local demand, network design, and planning history. A voltage label alone tells only part of the story.
Tips: When reviewing a substation, check the transformer nameplate and the voltage shown for each bus. A 110/10 kV transformer, for example, connects two different grid tiers. Local practice can differ. Verify the site data.
What Are the Standard Substation Voltage Levels in China? — China’s Power Grid Structure and Substation Voltage Classes
China’s grid uses a hierarchy of nominal voltage levels. The role assigned to each level varies by region and network configuration; operating voltages may differ from nominal values.
| System | Nominal voltage | Typical grid role | Notes |
| AC voltage classes |
| Extra-high voltage (UHV) | 1,000 kV | Long-distance, high-capacity bulk power transmission | The principal UHV AC class in China; used in selected backbone corridors. |
| Ultra-high voltage | 750 kV | Regional backbone transmission | Used mainly in parts of western and northwestern China. |
| Ultra-high voltage | 500 kV | Major interregional and provincial transmission; backbone-grid supply | A widely used high-voltage transmission and substation class. |
| High voltage | 330 kV | Regional transmission and subtransmission | A distinctive class used primarily in northwestern grid areas. |
| High voltage | 220 kV | Provincial and regional transmission; supply to major substations | A common backbone and subtransmission level. |
| High voltage | 110 kV | Regional subtransmission and urban or industrial supply | Commonly feeds lower-voltage distribution substations. |
| High voltage | 66 kV | Regional subtransmission and distribution supply | Used in some regions, including parts of northeastern China; less widespread nationally. |
| Medium voltage | 35 kV | Subtransmission, rural networks, and industrial distribution | Often supplies local distribution substations or larger customers. |
| Medium voltage | 20 kV | Distribution in selected urban and regional networks | Adopted in some areas as a distribution-network voltage. |
| Medium voltage | 10 kV | Primary distribution to local transformers and medium-voltage customers | A common urban and general distribution level. |
| Low voltage | 0.22/0.38 kV (220/380 V) | End-user supply from distribution transformers | Commonly described as 220 V single-phase and 380 V three-phase supply. |
| HVDC transmission classes (DC, not AC substation voltage levels) |
| High-voltage direct current (HVDC) | ±500 kV, ±660 kV, ±800 kV, ±1,100 kV | Bulk power transfer over long distances | Bipolar DC voltage classes used on selected links; converter stations connect HVDC links with the AC grid. |
Note: Voltage-class labels and local network practices can vary. The table summarizes nominal levels commonly encountered in China’s transmission and distribution networks.
Common Transmission and Subtransmission Voltage Levels
China’s transmission network uses several voltage tiers, each suited to a different distance and power flow. The national standard GB/T 156-2017 includes 1,000, 750, 500, 330, and 220 kV nominal AC levels. The 1,000-kV system carries bulk power across long distances. The 500- and 220-kV networks connect major generation areas, regional grids, and large substations.
Subtransmission commonly uses 110, 66, and 35 kV, though local practice varies. A 110-kV line may feed a city-area substation, while 35 kV can serve industrial loads or smaller towns. The 66-kV level remains in some regional networks, but it is not universal. These distinctions can look untidy on a map. They reflect different grid histories and local demand.
Scale matters. The China Electricity Council’s 2023 industry statistics reported about 894,000 km of transmission lines rated 220 kV and above. That figure shows how extensive the high-voltage backbone has become, but it excludes lower-voltage subtransmission circuits. China also operates ±800-kV direct-current links for long-distance transfers; that figure describes pole voltage, not an AC substation level. For equipment selection, engineers must check the rated voltage, insulation requirements, and the grid operator’s connection rules—not just the nearest familiar number.
Distribution Voltage Levels at Urban and Rural Substations
What Are the Standard Substation Voltage Levels in China?
Distribution Voltage Levels at Urban and Rural Substations
In Chinese cities, substations commonly step incoming 110 kV or 220 kV power down to 10 kV for local distribution. Some networks also use 20 kV, depending on regional planning and equipment. Nearby distribution transformers then supply buildings at 380 V three-phase or 220 V single-phase. A street-side transformer may serve several apartment blocks, shops, or smaller facilities.
Rural networks often use 10 kV feeders too, but long distances and scattered villages can change the design. In some areas, 35 kV lines carry power over longer routes before substations reduce it to 10 kV. The exact arrangement varies with terrain, load, and local grid plans. A remote village is not automatically supplied at a different voltage; its feeder length and transformer locations matter. This distinction is easy to overlook during site planning.
Tips: Check the local utility’s connection requirements before selecting equipment. Confirm both the incoming feeder voltage and the required low-voltage supply. Small details matter. A 220 V household supply is not the same as a 380 V three-phase service.
How Substations Transform Voltage Between Grid Levels
China’s grid uses several voltage levels, including 500 kV, 220 kV, 110 kV, 35 kV, and 10 kV. The exact path depends on the region and network design. Substations connect these levels, helping electricity travel efficiently over long distances and reach local distribution networks. The key equipment is the power transformer.
At a generating station, a transformer usually raises voltage for transmission. Higher voltage allows the same power to travel with less current, reducing line losses. Near cities and industrial areas, other transformers lower voltage in stages. A 220 kV supply, for example, may be reduced to 110 kV, then to 10 kV for local distribution. The sequence varies. Not every substation changes voltage; some mainly switch circuits or protect the network.
That distinction matters. Circuit breakers isolate faults, while protective relays detect abnormal conditions and signal breakers to act. Tap changers can adjust transformer output as demand and grid conditions shift. On site, large transformers may hum steadily, with cooling equipment keeping temperatures within operating limits. In practice, the neat voltage ladder is not always neat. Network layouts differ, and equipment settings require careful coordination. A small mismatch can affect power quality downstream.
Factors That Determine Substation Voltage Selection
China’s common substation voltage levels include 10, 35, 110, 220, and 500 kV. Higher-capacity transmission also uses 750 kV and 1,000 kV AC, while ±500 kV and ±800 kV are used for some DC links. GB/T 156-2017 sets standard system voltages, but a standard value alone does not determine a project’s choice.
Load density is a major factor. A compact urban district may need 110 or 220 kV incoming supply to serve heavy demand through shorter local networks. Remote generation sites often need higher voltages to move large power flows over long distances. Higher voltage can reduce current and transmission losses, but it also requires costlier insulation, switchgear, and clearances. The China Electricity Council’s 2023 power-industry statistics report about 1.52 billion kW of installed renewable capacity. That figure illustrates why planners must consider where generation connects, not only where consumers live.
Reliability and future growth matter too. Engineers assess fault levels, network connections, transformer capacity, land limits, and the consequences of an outage. A substation beside a dense industrial park may need spare transformer capacity; a rural site may face longer feeder distances and different maintenance constraints. A tidy voltage table is useful, but it can hide these trade-offs. Forecasts also miss sometimes, so staged expansion may be more practical than building for every projected peak at once.
What Are the Standard Substation Voltage Levels in China?
Common nominal AC voltage levels used across China’s power network, from distribution to ultra-high-voltage transmission.
How voltage is selected: Higher voltages can transfer more power over longer distances with lower current and reduced transmission losses. Substation voltage selection also depends on local demand, network structure, reliability requirements, equipment cost, and available land. The appropriate level varies by project and region; the chart shows nominal system levels, not a recommendation for a specific site.
