Urban rail transit UPS integration application solution

1. Introduction

Urban rail transit stations contain numerous weak current equipment systems, such as communications, signals, integrated monitoring, environmental monitoring, office automation, access control, automatic ticket vending and checking, automatic fire alarm, shielding doors, emergency lighting, substation integrated automation, etc. These systems are responsible for passenger transportation environment monitoring, information transmission and passenger guidance in subway stations, and are important or particularly important primary loads, requiring highly reliable power supplies to ensure power supply quality and continuity.

In previous rail transit projects, each weak current system in the station was equipped with its own power supply system, which had the disadvantages of repeated equipment configuration, low utilization rate, large floor space, and economic irrationality. In operation and maintenance, there were basically no professional power supply maintenance personnel in each system, resulting in insufficient or improper maintenance of the power supply system, which led to reduced battery capacity and failed to meet the backup time requirements. Domestic subways have experienced service interruptions due to battery problems.

With the development of power electronic equipment manufacturing technology and application technology, large-capacity power supply systems and advanced control technologies have been maturely used in communication and power systems, providing favorable conditions for the integration of various weak current power supply systems in rail transit projects. In existing subway projects in China, such as the Beijing Subway Airport Line project, preliminary attempts have been made to integrate the weak current system power supply of stations.

2. Customer Demand

1. Integration principles and requirements

The batteries and devices of each power system are integrated and centrally arranged to facilitate the unified maintenance and management of the power system. The centralized arrangement reduces the equipment room area and reduces the cost of station civil engineering. The hardware integration reduces the repeated configuration of equipment and realizes resource sharing to save equipment investment.

1. The weak current systems in the subway have very high requirements for the reliability of the power supply. When the power is cut off, the subway will stop operating or even cause personal injury, bringing inestimable losses. Therefore, each station power integration system is equipped with two sets of power supply devices (including rectifiers, inverters, batteries), load synchronization controllers, intelligent control units, etc.

2. Power supply and battery settings. Two sets of power supply devices are set up. During the project implementation, the power demand data of each device is collected in detail, and the more accurate capacity is calculated from it. In order to ensure long-term safe and reliable operation, the recommended maximum load of the UPS is generally 60% to 80% of the rated output power of the UPS. According to relevant engineering experience, the total load of each weak current system in a typical subway station is generally about 90kVA, so the capacity of each UPS can be selected as 120kVA.

3. Load synchronization controller. When the two UPS power supplies are not synchronized, the load voltage may be disturbed during the conversion process, and the current may be too large when connected, causing shutdown. If you want to convert reliably when the power supply is not synchronized, you must increase the interruption time (usually 15ms). This will be very unfavorable to the load (the interruption time of the computer load power supply is no more than 8-10ms).

4. Intelligent control unit. The intelligent control unit is responsible for controlling and managing the UPS power supply device battery and uploading the monitoring information of the UPS power supply integration system.

5. The overall design of the computer room should reflect the characteristics of a "green computer room and a technological computer room", respond to the call of the national "energy conservation and emission reduction" policy, and use advanced technology and design concepts to improve the overall energy-saving indicators of the system.

(II) Load types and demand analysis of each weak current system

1. Communication system. Load type: The power supply of computer network communication equipment of transmission, wireless, business telephone, private telephone, closed-circuit television, broadcasting, clock and other subsystems requires a continuous supply of AC220V power.

2. Signal system. Load type: signal system passenger information system and other computers, network equipment, control equipment; power supply requirements: can continuously supply AC380/220V power.

3. Comprehensive monitoring system (including environmental monitoring and access control). Load type: computers, network equipment, environmental monitoring and access control equipment; Power supply requirements: continuous supply of AC220V power.

4. Automatic Ticketing and Checking System (AFC). Load type: Computer, network equipment, AFC terminal equipment. Power supply requirement: Able to continuously supply AC220V power.

5. Office automation system. Load type: Computer, network equipment: The power supply must be able to continuously supply AC220V power.

6. Shield door system. Load type Shield door control, drive equipment, etc. Power requirements: Control equipment needs to be continuously supplied with AC220V control power supply, and drive equipment needs DC110V drive power supply.

7. Automatic fire alarm system. Load type: Computer network equipment, alarm controller, etc. require a continuous supply of AC220V power.

8. Substation DC auxiliary power supply. Load type: device power supply, control power supply, motor power supply, the power supply is required to be able to continuously supply DC220V power.

9. Station emergency lighting system. Load type. Including evacuation lighting and backup lighting. The power supply is required to be able to continuously supply AC220V power.

3. Power supply solution recommendations

According to the above customer needs, our company provides a dual-bus power supply system consisting of Delta HIFT highly intelligent fault-tolerant UPS.

1. UPS selection:

Taking into account the load conditions of the computer room and the requirements for reliability, it is recommended to use two Delta HIFT high-intelligence fault-tolerant 120KVA UPS to form a dual-bus power supply system.

The physical dimensions of this model are: 520×910×1695 (W×D×H) Weight: 230Kg

In addition, in response to the system's requirements for synchronous control, ordinary dual-bus systems will add an external synchronous controller between the two UPSs, which not only increases the cost, but the most critical thing is that the added external synchronous controller will become a single point of failure in the system, thus greatly reducing the reliability of the system. Delta's HIFT series UPS has a built-in synchronous control function, so the system avoids the synchronous controller from becoming a single point of failure in the system, while reducing system costs.

2. Power supply system selection:

In view of the importance of the system and the high reliability requirements, we chose the Delta HIFT high-intelligent fault-tolerant UPS system, which adopts a modular structure internally and forms a module N+X redundant structure. Therefore, the system power supply reliability is much higher than the dual-bus power supply system composed of ordinary UPS.

3. Battery capacity selection:

The system has a 30-minute backup discharge.

Battery model: DCF126-12/200 12V 200Ah battery

Number of batteries: 40 (one set)

The UPS power integration system imports an AC380V power supply from the two 0.4V bus sections of the step-down station as the input power for the two UPS devices.

During normal operation, two UPS devices run in parallel and share the load current to provide AC380/220V uninterruptible power supply to each power system. The capacity of each UPS can meet the total capacity requirements of the system. An intelligent control unit is set up to cut off various loads in sequence according to the set time.

The shield door system and substation auxiliary power supply emergency lighting are independently equipped with backup power supplies and are not included in the scope of power integration.

Solution system diagram:

Solution configuration list:

4. Analysis of the advantages of the solution

As enterprises have higher and higher requirements for availability, the necessity of configuring a power supply system with fault-tolerant technology for computer rooms or data centers has become more and more prominent. Fault tolerance means using redundant resources to enable the UPS system to tolerate faults, that is, in the event of a fault, the system's inverter output can still be ensured to provide clean and stable power for the network system composed of key equipment such as servers and storage.

HIFT (High-Intelligent Fault-Tolerance) is the latest high-intelligent fault-tolerant UPS launched by Delta. Its significant advantages and value to customers include but are not limited to:

◆ High system reliability

System reliability calculation formula:

HIFT UPS module 2+1 redundant system reliability:

HIFT UPS module 1+2 redundant system reliability:

The N+X redundant power supply system composed of HIFT UPS has a close relationship with the reliability of the system, and the lower the actual load, the higher the system redundancy and reliability. This is exactly what ordinary UPS cannot match.

◆ High system reliability

Availability is a measure of a system's ability to provide continuous service.

HIFT UPS adopts module N+X redundancy technology, which can hot-swap faulty modules online, and MTTR can be regarded as 0.

Comparison of availability of different power supply solutions (MTBF takes 200,000 hours as an example)

HIFT UPS can reduce "recurrence failure" by 500-1000

◆ Expand capacity as needed

Rapidly changing businesses require enterprise computer rooms and data centers to be flexible. When more IT applications emphasize dynamic structures, must the UPS power supply system supporting these applications be in place in advance, or can it be flexibly configured as needed?

Traditional UPS customers must meet the foreseeable maximum load power requirements in the future when planning. For example, although the total load capacity is only 20kVA now, it may grow to 60kVA in the future. Customers usually directly purchase UPS with a power of 100kVA during initial configuration to avoid insufficient capacity due to future upgrade difficulties.
HIFT UPS adopts a modular structure and can expand capacity online at any time and on demand in units of 20kVA within a wide range of 20kVA to 480kVA. Customers no longer need to invest a large amount of money in advance just for future possibilities. (See the figure below)

The flexibility of HIFT UPS, which allows the configuration of capacity closest to the actual demand capacity, not only reduces the initial purchase cost of UPS, but also reduces the configuration and energy consumption of supporting equipment (such as air conditioners), effectively preventing unnecessary expenses caused by advanced and over-scale design of infrastructure.

◆ High efficiency and energy saving - reduce operating costs

Green energy conservation is not only the responsibility of enterprises to the society, but also closely related to the operating costs of enterprises.

Generally, the lower the load, the lower the UPS efficiency. However, for HIFT UPS, even if the load is only 15% of the rated capacity, the overall efficiency is over 90%; when the load reaches 27%, the efficiency is as high as 94%. Every small step increase in efficiency is a big step in saving energy expenditure.

HIFT UPS efficiency curve

Benefit Analysis:

UPS power consumption per year:

Air conditioning cooling cost (calculated based on the air conditioner's EER (energy efficiency ratio) of 3.3):

According to the above calculation, the HIFT UPS is compared with the ordinary UPS, only from the electricity cost.

The annual electricity savings from two 80KVA HIFT UPSs = (15540+4535) kWh × 1.8 yuan × 2
= 72270 yuan.

◆ Small accessories, big management

HIFT UPS, combined with SNMP card and environmental monitoring module, can comprehensively monitor and manage the power environment of the computer room, including temperature, humidity, fire, smoke, water leakage, and access control.

5. Powerful technical support and after-sales service network

Zhongda Telecom has 34 service outlets across the country, with more than 500 sales service engineers providing users with a full range of services before, during and after sales to ensure that users receive technical support in the first place. The content is as follows:

Service tenet: To provide uninterruptible power supply products with excellent quality and services that will make customers 100% satisfied.

Pre-sale service:

● Provide customers with power supply planning so that they can enjoy the most economical and effective Delta UPS configuration and network system management solutions.

● The company can meet customers' special requirements on a project basis and provide a variety of uninterruptible power supply products.

● Customers can consult the Shanghai head office, local branches and agents about the technical characteristics of Delta UPS products or search online.

www.deltagreentech.com (Chinese), Delta Greentech (real name on the Internet)

● Through various media, national exhibitions and new product launches, customers can understand the functions and features of Delta UPS's latest products.

● The company has sufficient inventory and provides fast installation services to meet customers' requirements for improving the electricity environment.

Sales service:

● During installation and commissioning, on-site training is provided to users so that they can independently operate, use and maintain the equipment. The training content includes structural principles, fault diagnosis and temporary treatment methods, and requires the ability to independently operate the uninterruptible power supply and eliminate emergency faults.

● Specialized technicians will be responsible for the preparation of the customer's use environment, including power input, output, battery, cable specifications, etc. The installation and commissioning of UPS will be the responsibility of qualified technicians designated by our company.

After-sales service:

● After the product is sold, you will enjoy the installation, commissioning and usage explanation services of the local agent, and enjoy the Delta brand guarantee and lifelong maintenance.

● Provide regular training to Delta UPS users.

● During the free maintenance period, technicians will provide regular UPS maintenance.

● The nationwide Delta UPS maintenance network ensures that your problems can be resolved in the shortest possible time.

The company's 24-hour service hotline: 021-58639595

VI. Conclusion

In summary, the UPS power integration of weak current systems in urban rail transit is to adapt to the rapid development of rail transit. It plays a great role in the rational allocation of power resources, improves the economy and safety of weak current systems in rail transit, and reduces the maintenance. With the rapid development of rail transit, UPS integrated power will surely be rapidly developed and widely used.