In recent years, with the continuous development of cities in our country, the improvement of municipal construction facilities has been promoted, creating a favorable living environment for residents and meeting their living needs. The construction of urban utility tunnels has enhanced both the aesthetics and functionality of the city, contributing to the perfection of the urban system. Electrical design significantly impacts the effectiveness of utility tunnel construction, thus, scientific and reasonable measures should be taken to strengthen the electrical design standards of utility tunnels.
Section II: Overview of Integrated Utility Tunnel Electrical Design
The Comprehensive Utility Tunnel, as a type of underground building corridor, provides a public space for the laying of power, thermal, water supply, communication, and gas pipelines. Typically, the tunnels are set beneath the urban road green belts. Electrical engineering is an important auxiliary project of the comprehensive utility tunnel, mainly including power supply and distribution systems, lighting systems, cable laying systems, and grounding systems. These systems can provide electricity for lighting, drainage, fire protection, and ventilation systems, ensuring stable and safe operation of all systems. Currently, the construction level of comprehensive utility tunnels in our country has been effectively improved, which also promotes the level of electrical design for comprehensive utility tunnels. However, compared to developed countries, the electrical design level of comprehensive utility tunnels in our country is still relatively low, and further discussion on the electrical design of comprehensive utility tunnels is required.
Section III: Electrical Design Measures for the Comprehensive Pipeline Tunnel
Load Grading and Main Distribution Systems
During the electrical design of the comprehensive pipeline, the design should comply with the prescribed load grading standards. Items classified as second-level load design include the accident fans in the natural gas pipeline chamber, emergency shutdown valves, monitoring and alarm equipment, fire-fighting equipment, and emergency lighting. The rest are designed according to the third-level load. For the main power supply system, a two-way independent loop power supply is adopted, which allows both power sources to operate simultaneously. If one power source fails, the other takes over to prevent the system from shutting down. Electrical equipment should be configured within the substation, including a 10kV high-voltage distribution device and two 10/0.4KV dry-type transformers. The low-voltage side wiring is in a single busbar sectioning arrangement, with busbar circuit breakers set between the two busbars. Additionally, automatic power source switching should be provided.
2. Power Supply and Distribution System Structure
The comprehensive pipeline power station mainly consists of three types: above-ground substation, underground substation, and box-type substation. During the specific design process, it is essential to scientifically and reasonably tailor the design to the actual circumstances. Generally, the comprehensive pipeline is constructed beneath green belts, allowing for the use of box-type substations below these green spaces. This arrangement not only achieves a favorable landscape effect but also conserves land. Within the equipment layer of the pipeline ventilation shaft, appropriate equipment should be installed, including power and lighting distribution cabinets, emergency lighting distribution boxes, pipeline lighting distribution boxes, monitoring distribution boxes, and fan control boxes, to power the systems of fire compartmentation. For the emergency lighting system, gas chamber fans, and monitoring equipment in the comprehensive pipeline, a dual-power supply method should be adopted, and set to an automatic switching mode.
Additionally, appropriate power supply and distribution equipment should be utilized in accordance with the comprehensive utility tunnel electrical distribution requirements to ensure the protection level meets the installation standards. For the natural gas pipeline cabin, electrical equipment with excellent explosion-proof performance should be employed. Moreover, the power supply equipment should be installed reasonably, ensuring ease of operation and maintenance.
Electrical Control and Protection
The fan utilizes a combination of manual and automatic control methods. Manual control is set up at the fan control box, and the ventilation fan control switch should also be located at each division's personnel entrance and exit. The monitoring center can obtain the operational conditions of the fans and remotely control their operation. The water pump employs the same control method as the fans, with the PLC receiving the pump signals. Professional monitoring equipment is used for real-time monitoring of the power supply for the fire protection load distribution box. Standard protectors are utilized to protect the low-voltage distribution, with protective measures including ground fault protection, short-circuit quick-break, overloading, and delayed breaking. For motors, phase loss protection, short-circuit fault protection, and ground fault protection are set up; for submersible motors, leakage protection and ambient temperature protection are installed. Within the substation, an electrical fire monitoring system should also be set up, as it monitors the distribution circuit and related systems. In the event of a leakage or other accident, it can promptly sound an alarm and transmit it to the fire control center for emergency handling.
4. Lighting System Design
Lighting systems are an essential component of the integrated utility tunnel electrical system, and thus should be designed according to certain standards. The specific design standards are as follows, as shown in the table:
During the installation of the utility tunnel lighting system, appropriate lighting fixtures should be used, such as T5 waterproof and moisture-proof fluorescent lamps. For emergency lighting fixtures, the illuminance can be appropriately reduced to about 1/3 of normal lighting, and powered by EPS. The emergency time should also meet the standard requirements, generally not less than 90 minutes. The lighting fixtures used should also meet the required protection level. Signage lights should be set up at fire exit corridors, tunnel entrances and exits, and feeding ports, all powered by EPS. The control method of lighting fixtures in the lighting distribution box is a combination of manual and automatic, or PLC control can also be adopted. In the event of a fire, the fire automatic alarm system will link and control to disconnect the lighting facilities and activate the emergency lighting.
5. Lightning Protection and Grounding System Design
The lightning protection and grounding system for the comprehensive pipeline trench primarily protects against induced lightning, thus surge protectors can be utilized. Additionally, an integrated grounding system can be implemented to connect various electrical equipment with grounding protection lines, controlling the integrated grounding resistance to within 1 ohm. Within the comprehensive pipeline trench, a three-dimensional and closed grounding system should also be formed, allowing for the welding of the structural main reinforcement of the trench.
AcrelEMS-UT Comprehensive Utility Tunnel Energy Management Platform
1. Platform Overview
The AcrelEMS-UT Integrated Pipeline Energy Management Platform integrates power monitoring, energy management, electrical safety, lighting control, and environmental monitoring. It provides data support for establishing a reliable, secure integrated pipeline management system. Through its design in data collection, communication networks, system architecture, interlock control, and comprehensive data services, it addresses the fundamental issues of strong internal interference, numerous users, and complex coordination in the management process of integrated pipelines. This significantly enhances the reliability and manageability of system operations, and improves the efficiency of usage and recovery of pipeline infrastructure, environment, and equipment.
2. Platform Composition
The Ankelei Urban Underground Utility Corridor Energy Efficiency Management System is a deeply integrated automation platform that incorporates a 10KV/O.4KV substation power monitoring system, substation environmental monitoring system, intelligent motor monitoring system, electrical fire monitoring system, fire equipment power supply system, fire door monitoring system, intelligent lighting system, fire emergency lighting and evacuation guidance system. Users can access data through browsers or mobile apps, enabling centralized monitoring, unified management, and coordinated dispatch of the corridor's power usage and safety from a single platform, while also meeting the requirements of reliability, safety, stability, and orderliness in the corridor's power supply.
3. Platform Topology Diagram
4. Platform Subsystem
4.1 Power Monitoring
Our Power Monitoring primarily targets 10/0.4kV ground or underground sub-stations. It protects and monitors the high-voltage circuit configurations of micro-computer protection devices and multi-functional instruments within the sub-stations. It also equips the 0.4kV outgoing lines with multi-functional measuring instruments for measuring and controlling electrical parameters and energy consumption of the outgoing circuits. It can monitor real-time operations of switchgears in high and low-voltage power supply and distribution systems, micro-computer protection and measurement devices of transformers, generator control panels, ATS/STS, UPS systems, including remote control, remote signaling, remote measurement, remote adjustment, accident alarms, and records.
4.2 Environmental Monitoring
Environmental monitoring encompasses the collection, display, and early warning of temperature and humidity, smoke and heat sensors, waterlogging and immersion, flammable gas concentrations, access control, video surveillance, air conditioning, and fire data. It also integrates with third-party systems, including pump and exhaust fan equipment within the corridor's rooms, to achieve comprehensive environmental monitoring of the corridor.
4.3 Motor Monitoring
The Madar Monitoring System provides protection, remote measurement, remote signaling, and remote control functions for the motor in the pipeline, ensuring protection, monitoring, and alarm for abnormal conditions such as overload, short circuit, phase loss, and leakage. In cases requiring it, linkage control can be set up.
4.4 Electrical Safety
The AcrelEMS-UT Energy Management System is equipped with electrical fire sensors, temperature sensors, fire equipment power sensors, fire door status sensors for electrical safety hazards in distribution systems. It connects to the status display of fire evacuation lighting and indicator lights in real-time, and continuously monitors the battery temperature and internal resistance of the UPS. In case of anomalies, it provides timely warnings through sound, light, SMS, and APP.
4.5 Smart Lighting Control
Fire compartments are individually controlled, with intelligent control panels and local drivers installed within each compartment. Switch drivers are connected to the fire alarm system, receiving fire alarm information and forcing the opening of the driver circuit.
Intelligent lighting sensors are installed above the corridor, enabling lights to automatically turn on when personnel enter, remain on continuously while inside, and turn off upon exit.
③ In addition to on-site control methods, centralized control can be achieved via the computer platform, enabling real-time remote monitoring of the current area's lighting conditions, with the option to remotely control the lighting as needed.
④ Due to the wide distribution and long distances of the on-site modules, in addition to on-site control methods, centralized control can also be achieved through the computer terminal. Real-time remote monitoring of the lighting conditions in the current area is available, and remote control of the lighting in that area can be performed as needed.
⑤ The system supports various control methods including single control, area control, automatic control, sensor control, timing control, scene control, and dimming control, and features delayed control to prevent simultaneous lighting loads from impacting the distribution system. Modules are independent of the system and can operate autonomously. Each module is equipped with a time module, capable of automatically identifying sunrise and sunset times based on latitude and longitude to enable automatic control functions.
Section V: Hardware Selection List for Relevant Platforms
1. Power Monitoring and Distribution Room Environmental Monitoring System
2. Smart Lighting System
3. Electrical Fire Monitoring System
Fire Equipment Power Supply Monitoring System
Fire Door Monitoring System
Emergency Lighting and Evacuation Signage System
Six, Conclusion
In summary, the utility tunnel plays a crucial role in China's urban construction, providing operational space for various pipelines and contributing to the continuous improvement of our urban infrastructure. Electrical design is a significant component of utility tunnel design, directly impacting its effectiveness. Therefore, during the utility tunnel design process, it is essential to adopt scientific and reasonable measures to strengthen the electrical design of the distribution system, power supply system, and lighting system, ensuring the safe and stable operation of electrical equipment and continuously enhancing the level of electrical design in utility tunnels.
