Substation site dc power supply

I. product introduction

The on-site dc power supply of substation is the energy base of all the equipment. Once the dc equipment has problems, it will make all the monitoring and protection equipment lose power, and the whole protection equipment will be paralyzed, which will cause considerable harm. System set degree is high, high reliability and long service life, high intelligent degree, small volume, convenient mobile etc., can be widely used in electric power system, power plant, substation, power plants, and other users of dc equipment, such as petrochemical, mining, railway and so on, can solve the scene emergency dc power supply and battery failure problems.

 

Ii. System features

2.1 simple structure

The charging part of the emergency power supply and the battery part are installed separately, which is convenient for on-site use.

The battery part is installed in the form of battery cartridge, which is easy to operate on site.

The system wiring is simple and clear, which is convenient for quick installation and saves the time of field operation.

 

2.2 high intelligence

The system adopts decentralized control system, modular structure, simple screen, flexible configuration.

The monitoring module adopts liquid crystal Chinese character display, which can be used to set the parameters of each part of the system.

The module has the function of adjusting output voltage and current smoothly, and has the function of battery charging temperature compensation.

Battery automatic management and protection, real-time automatic monitoring of battery terminal voltage, charging current, and the battery floating charge intelligent control, intermittent charging method, more conducive to extend the battery life.

With the battery over - voltage and charging over - current alarm functions.

Adopting GPRS data communication transmission mode, unattended and real-time monitoring of equipment operation data can be realized.

The background data center monitors the running status of each equipment in real time, notifies the users in time when problems are found, and makes maintenance more timely.

 

2.3 high reliability

Adopt the modular design of switch power supply, N+1 hot backup.

The charging module can be plugged and unplugged by electric heating, which greatly reduces the average maintenance time.

All the key components of the system are imported famous brand products of high quality.

Hardware low difference independent uniform current technology, the maximum output current imbalance between modules is less than 3%.

The rectifier and battery can be replaced without interruption to ensure more reliable system.

The battery adopts the international advanced lithium battery pack, which has a long service life and is more safe and reliable in use.

The system design adopts IEC and other international standards to effectively prevent the failure of the on-site monitoring system.

 

Technical parameters

3.1 cabinet:

Size:

The overall size of the cabinet is: height × width × depth =1200mmX800mmX600mm

The charging box is: height × width × depth =400mmX800mmX600mm

Battery box: height × width × depth =800mmX800mmX600mm

Capacity configuration:

The capacity of the charger is 2×10 rectifier.

The battery capacity is 20AH iron lithium battery pack.

One charge control monitor.

The system structure is shown in the right picture:

3.2 high-frequency switching power supply:

1) system capacity: 20A.

2) ac power distribution: ac input is 380V, one way.

3) dc power distribution: one dc output switch with a capacity of 32a.

4) can connect to battery 1. Circuit breaker protection.

 

5) technical indicators

 

Input voltage 380V±20%, 50Hz±5%

Output voltage rating: 220V

Floating charging voltage 240V (adjustable)

Uniform voltage 252V (adjustable)

The unbalance degree of uniform flow in parallel operation is less than 3%

55 db or less noise

Soft start time 3~8s

Height × width × depth = 1200×800×600mm

Module capacity 10A/ module

Power factor ≥.92

Power is 92% or higher

Voltage stability accuracy ≤±0.2%

Cooling mode intelligent cooling

 

6) monitoring unit

Communication function: GPRS communication mode is adopted to meet the requirements of unattended places, and maintenance is more convenient.

Display mode: full Chinese menu interface, high resolution liquid crystal display, the system has a good man-machine interface, intuitive monitoring, simple operation.

Alarm mode: with perfect protection and alarm function.

Battery management: it can realize manual equalization/floating charge conversion and automatic equalization/floating charge conversion, periodic automatic equalization management, temperature compensation and other functions, single battery data collection, battery overcharging automatic cut-off function.

7) protection

Ac input overvoltage and undervoltage protection.

Dc output overvoltage and undervoltage protection.

Module current limiting protection.

System overcurrent protection.

 

3.3 lithium battery

1) technical features

 

Rated voltage 3.2v

Rated capacity 20Ah

Charging type constant pressure floating charging

Floating charging voltage 3.4v/monomer (20℃)

Charging current 10A (0.5c10)

Battery discharge rate 8In termination voltage not less than 2.85v

Battery terminal voltage 240V

The battery self-discharge at room temperature for 28 days <1%

Termination voltage 2.5v

Cycle life 1500 times

 

2) structural characteristics

A) type: frame type, structure size: height × width × depth = 240×240×430mm, one group contains 5 frames.

B) the metal parts such as bolts and nuts shall be hot-dip galvanized.

C) small pressure drop of connection line.

D) the battery frame is well sealed with no exposed conductive body.

 

Performance comparison between lithium battery pack and lead-acid battery

4.1 energy characteristics:

Lithium battery is environmentally friendly; Lead-acid batteries are polluting.

 

4.2 description of charging characteristics of lithium battery:

With 3.6v voltage, the residual capacity of lithium iron battery is 99.1% after 418 days of floating charge at 25℃, 98.2% after 418 days of floating charge at 42℃, and 90% after 270 days of floating charge at 55℃. The floating charging life of lithium iron battery is 20 years at 25℃, 10 years at 42℃, about 4 times that of lead-acid battery, and 2.5 years at 55℃.

 

4.3 discharge characteristics of lithium battery:

The discharge curves of 100Ah lithium iron battery 0.2c and 0.5c are shown in the figure above.

 

Iron lithium battery has a good discharge platform.

4.4 comparison of cycle life of lithium battery and lead-acid battery:

At room temperature, 100Ah lithium iron battery was charged and discharged 1367 times at 40A (0.4c) current 100%, and the residual capacity of the battery accounted for 84.47% of the initial capacity. Meet the enterprise standard 1000 cycles, battery residual capacity more than 70% of the requirements.

The 100Ah lead-acid battery was circulated 171 times with 10A (0.1c) current, and the remaining battery capacity accounted for 75.3% of the initial capacity.

Compared with lead-acid batteries, iron-lithium batteries have excellent recycling performance, with a cycle life of about 10 times that of lead-acid batteries.

 

Lithium battery cycle life test figure: lead-acid battery cycle test figure: 4.5 comparison of temperature characteristics between lithium battery and lead-acid battery

At 55℃, 100Ah lithium iron battery charged and discharged 1062 times with 40A (0.4c) current, and the residual capacity of the battery accounted for 74.7% of the initial capacity.

The 100Ah lead-acid battery was circulated 130 times with 10A (0.1c) current, and the remaining battery capacity accounted for 65.2% of the initial capacity.

Compared with lead-acid batteries, iron-lithium batteries have a high-temperature cycle life of about nine times that of lead-acid batteries.

 

4.6 comparison of discharge characteristics between lithium battery and lead-acid battery at different temperatures

Discharge temperature iron lithium battery discharge capacity lead acid battery discharge capacity

50 ℃ 101.8% 78%

20 ℃ 100% 68%

10 ℃ 96.8% 62%

0 ℃ 86.3% 58%

- 10 ℃ 50.0% 50%

- 20 ℃ 40% 31.6%