The prefabricated substation mainly consists of multi-circuit high-voltage switchgear systems, armored busbars, integrated substation automation systems, communication, telecontrol, metering, capacitor compensation, DC power supply, and other electrical units. These components are housed in a moisture-proof, rust-proof, dust-proof, rodent-proof, fire-proof, anti-theft, heat-insulated, fully enclosed, and movable steel structure enclosure, achieving mechatronic integration and fully enclosed operation. The main features are as follows:
Advanced Technology, High Safety and Reliability
Enclosure Structure: The enclosure is made of aluminum-zinc coated steel plate using standard container materials and processes, offering excellent corrosion resistance with a service life of up to 20 years. The inner lining uses aluminum alloy panels, and the interlayer is filled with fire-resistant insulation material. Air conditioning and dehumidification equipment are installed inside, ensuring stable operation in harsh environments ranging from -40°C to +40°C.
Electrical Equipment: Primary equipment includes fully enclosed high-voltage switchgear (such as XGN type), dry-type transformers, dry-type instrument transformers, vacuum circuit breakers, etc., achieving a fully enclosed, fully insulated structure with zero risk of electric shock. The secondary system uses a microcomputer-based integrated automation system, supporting unattended operation.
Factory Prefabrication, Short Construction Period
Designers only need to provide a primary single-line diagram and requirements for external equipment to select the appropriate substation model. All equipment is installed and debugged in the factory, realizing factory-based substation construction. On-site work is limited to substation positioning, cable connections, and protection calibration. The entire process from installation to commissioning takes only 5–8 days, greatly reducing the construction period.
Flexible Combination
Each enclosure forms an independent system, allowing flexible combination. Users can freely configure modules according to actual needs to meet safe operation requirements.
Lower Investment, Quick Returns
Investment is reduced by 40%–50% compared to conventional substations of the same scale. The use of oil-free equipment fundamentally eliminates leakage issues, enabling condition-based maintenance, reducing maintenance workload, and saving operating costs, resulting in significant economic benefits.
Small Footprint
The footprint is only 1/10 that of a conventional substation of the same scale. It can be installed in street corners, squares, factory corners, and other spaces, aligning with land conservation policies.
Aesthetic Appearance, Harmonious Integration with Environment
The enclosure is made of aluminum-zinc coated steel plate using container manufacturing technology, offering an attractive appearance. By choosing different exterior colors, the substation can easily blend with the surrounding environment (such as residential communities, parks, ports, etc.). It can be used as either a fixed or mobile substation.
Based on structural form and integration method, prefabricated substations are mainly divided into three types:
Assembled Type
High-voltage and low-voltage complete sets of equipment and the transformer are installed in a metal enclosure with an operating aisle inside. This type has a large volume and is rarely used today.
Combined Device Type (European-Style Substation / Standard Type)
Instead of using existing complete sets of equipment, high-voltage and low-voltage control and protection devices are directly installed inside the enclosure. The design is maintenance-free with no operating aisle, resulting in a smaller enclosure. Originating from European technology, it is also known as a European-style substation.
Integrated Type (American-Style Substation / Compact Type)
The high-voltage control and protection devices are simplified, and the high-voltage and low-voltage distribution devices are integrated with the transformer main body inside the transformer tank, forming a single unit. It has an even smaller volume, approximately one-third that of a European-style substation of the same capacity. Originating from American technology, it is also known as an American-style substation.
European-style substations are widely used in China. The interior is divided into three independent compartments (high-voltage compartment, transformer compartment, and low-voltage compartment), arranged in a "three-section" layout, commonly in horizontal or triangular configurations. Common models include ZBW and XWB.
High-Voltage Compartment: Equipped with ring network units, dual-line, or terminal load switches. It has a small footprint and is compatible with ring network cabinets. It features comprehensive anti-misoperation interlocking functions. The high-voltage equipment often uses a combination of load switches and fuse-switches; the fuses are equipped with strikers to prevent phase loss protection. For ring network configurations, 11kV 33kv 35kv cable outlets are equipped with ground fault indicators and zero-sequence sensors.
Transformer Compartment: Can be equipped with oil-immersed or dry-type transformers, using Dyn11 connection. Heat dissipation is achieved through natural ventilation or forced ventilation at the top.
Low-Voltage Compartment: Equipped with metering and reactive power compensation devices. Secondary circuits and the number of outgoing lines can be customized according to user requirements.
Structure and Protection: Each compartment is equipped with lighting controlled by door switches. Transformer protection uses a series connection of a backup fuse and an insertion fuse. High-voltage cables are connected to insulated bushings and then to elbow-type cable plugs, achieving a fully shielded and fully sealed connection. The elbow-type cable plug is load-break switchable.
To ensure safe and stable operation, the following operational guidelines must be followed:
Site Selection and Installation: The substation should be placed on higher ground to avoid water accumulation. When pouring the concrete platform, reserve space for cable entry and exit. The foundation must be stable; if corrosive soil is present, it must be replaced and compacted.
Grounding System: The grounding and neutral systems share a common grounding grid. The substation must have two reliable connections to the grounding grid. Connection points should be regularly checked for looseness and corrosion, and the grounding resistance should be measured periodically to ensure it does not exceed 4Ω.
Ventilation and Heat Dissipation: Natural ventilation is the primary cooling method. Do not stack objects around the substation, especially near the transformer compartment door. Regularly clean the louvers and vents to ensure equipment temperature does not exceed allowable limits.
Operating Procedures: After a low-voltage circuit breaker trips, the cause must be identified before re-energizing to prevent accident escalation. When replacing non-load-break high-voltage fuses, the transformer must be de-energized, and mechanical interlocks must be correctly disengaged using insulated operating rods.
Inspection and Maintenance: The high-voltage compartment should be equipped with zinc oxide surge arresters that are easy to test and replace. Equipment such as ring network switches and transformers should be regularly inspected, and defects must be promptly addressed. If equipment is out of service for more than three months, a full preventive test must be performed before re-commissioning.
Safety Protection: All cable entry and exit openings must be properly sealed to prevent small animals from entering. The enclosure must display clear high-voltage hazard warning signs and equipment nameplate numbers.
