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I. Product introduction
The field DC power supply of transformer substation is the energy foundation of all the equipments, the failure of DC equipment will result in power off of all the monitoring and protection equipments on the site, the whole protection equipment will fail and cause serious harmful consequence.
With the characteristics of high system integration, high reliability, long service life, high intelligent degree, small volume, convenient relocation, etc., can be widely applied in various power plants, hydropower stations, transformer substations of power system, and other users that use DC equipment (such as petrochemical, mining, railway), can solve the emergent field DC power supply and battery failure.
II. System characteristics
2.1 Simple structure
The emergency power supply charge part and battery part adopt divided installation, which is convenient for field use.
The battery part installation adopts battery socket, the field operation is simple and convenient.
The system connection is simple and easy, convenient for fast installation, and saves time for being put into operation.
2.2 Highly intelligent
The system adopts decentralized control, modularized structure, simple screen design and flexible configuration.
The monitoring module adopts LCD Chinese display, the parameters of each part of the system can be set through the monitoring module.
The module has function of smoothly regulating output voltage and current, and the function of battery charging temperature compensation.
Battery automatic management and protection, real-time and automatic monitoring of terminal voltage, charging current of battery, intelligent control over average floating charge of battery, interval charge method is favorable for prolonging the batter life.
Function of battery over/under voltage and charge overcurrent alarm.
Adopt GPRS data communication transmission, realize unattended, real-time monitoring of equipment operating data.
The background data center makes real-time monitoring on the operating status of each equipment, and can notify the user in time if there is any problem, the maintenance is in time.
2.3 Highly reliable
Adopt modularized design of switch power supply, N+1 warm standby.
The power module can realize hot plug, the average maintenance time is greatly reduced.
All the key components of the system adopt high-quality imported famous brand products
The hardware low dropout automatic current sharing technology, the maximum imbalance of the output current between the modules is less than 3%.
The rectifier and battery can adopt continuous replacement scheme and guarantee the reliable system.
The battery adopts international advanced lithium battery with ultra long service life, the use is safer and more reliable.
The system design adopts international standards as IEC, and effectively prevents from field monitoring system failure.
III. Technical parameters
3.1 Cabinet:
Dimension: Total cabinet dimension: Height*width*depth=1200mm*600mm*600mm
Charge box dimension: Height*width*depth=400mm*600mm*600mm
Battery box: Height*width*depth=800mm*600mm*600mm
Capacity configuration:
Charger capacity is 2*10 rectifier.
Battery capacity is 20AH Li-Fe battery.
One charge control monitor.
The system diagram is as follows:
3.2 High-frequency switch power supply:
1) System capacity: 20A.
2) AC distribution: one AC input, 380V.
3) DC distribution: one DC output switch, with the capacity of 32A.
4). Can be connected to 1 group of battery. Adopt breaker protection.
5) Technical index
Input voltage: 380V¡À20%£¬50Hz¡À5%
Output voltage: Rated value: 220V
Floating charge voltage: 240A (settable)
Even voltage: 252V (settable)
Current equalization imbalance in parallel operation: ¡Ü3%
Noise: ¡Ü55db
Soft start-up time: 3~8s
Structure dimension: Height*width*depth=1200*600*600mm
Module capacity: 10A/module
Power factor: ¡Ý.92
Power: ¡Ý92%
Voltage stabilizing precision: ¡Ü¡À0.2%
Cooling method: Intelligent cooling
6) Monitoring unit
Communication function: Adopt GPRS communication method, meet the requirement of unattended place, the maintenance is more convenient.
Display method: Full Chinese menu interface, high resolution LCD, good human-machine interface, intuitive monitoring, simple operation.
Alarm method: Improved protection and alarm function.
Battery management: Realize manual average/floating charge switching and automatic average/floating charge switching, periodic automatic average charge management, temperature compensation, single cell data collection, battery overcharge automatic cut-off.
7) Protection
AC input over, under voltage protection.
DC output over, under voltage protection.
Module current limiting protection.
System overcurrent protection.
3.3. Lithium battery
1) Technical characteristics
Rated voltage: 3.2V
Rated capacity: 20Ah
Charge mode: Constant voltage floating charge
Floating charge voltage: 3.4V/unit (20¡æ)
Charging current: 10A (0.5C10)
Battery rate discharge: 8In The final voltage is no lower than 2.85V
Battery terminal voltage: 240V
Batter self discharge: <1% if being placed for 28 days in room temperature
Final voltage: 2.5V
Cycle life: 1500 times
2) Structure characteristics
a) Model: Socket type, structure dimension: Height*width*depth=240*240*430mm, 5 sockets in one group.
b) The metal parts as bolt, nut, etc. are hot dipped.
c) The voltage drop of connection wire is small.
d) The battery frame is well sealed without exposed conductor.
IV. Performance comparison between lithium battery and lead-acid battery
4.1 Energy characteristics:
Lithium battery is environmental battery; lead-acid battery is pollution battery.
4.2 Charge characteristics of lithium battery:
The residual capacity of Li-Fe battery is 99.1% after being floating charged under 3.6V, 25¡æ for 418 days, the residual capacity is 98.2% after being floating charged under 42¡æ for 418 days, the residual capacity is 90% after being floating charge under 55¡æ for 270 days.
25¡æ floating charge life of Li-Fe battery is 20 years, 42¡æ floating charge life is 10 years, which is 4 times longer than lead-acid battery, the 55¡æ floating charge life is 2.5 years.
4.3 Discharge characteristics of lithium battery
100Ah Li-Fe battery 0.2C, 0.5C discharge curve are as shown in the above diagram.
Li-Fe battery has good discharge platform
4.4 Cycle life comparison between lithium battery and lead-acid battery:
In room temperature, 100Ah Li-Fe battery is charged and discharged for 1367 times at 40A (0.4C) current, the residual battery capacity occupies 84.47% of the original capacity, which conforms to the requirement of enterprise standard that the cycle shall be 1000 times, and the residual battery capacity shall be greater than 70%.
100Ah lead-acid battery is circulated for 171 times at 10A (0.1C) current, the residual battery capacity occupies 75.3% of the original capacity
Compared with lead-acid battery, the Li-Fe battery has excellent cycle performance, and the cycle life is 10 times longer than lead-acid battery.
Lead-acid battery cycle test diagram
4.5 Temperature characteristics comparison between lithium battery and lead-acid battery:
In 55¡æ, 100Ah Li-Fe battery is charged and discharged for 1062 times at 40A (0.4C) current, the residual battery capacity occupies 74.7% of the original capacity.
100Ah lead-acid battery is circulated for 130 times at 10A (0.1C) current, the residual battery capacity occupies 65.2% of the original capacity. Compared with lead-acid battery, the high temperature cycle life of Li-Fe batter is 9 times longer than the lead-acid battery.
Temperature characteristics curve of lithium battery
4.6 Discharge characteristics comparison between lithium battery and lead-acid battery in different temperatures
| Discharge temperature |
Discharge capacity of Li-Fe battery |
Discharge capacity of lead-acid battery |
50¡æ |
101.8% |
78% |
20¡æ |
100% |
68% |
10¡æ |
96.8% |
62% |
0¡æ |
86.3% |
58% |
-10¡æ |
50.0% |
50% |
-20¡æ |
31.6% |
40% |
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