Application Background:
Launched in 2012, the West-East Gas Pipeline Project is my country's longest and largest diameter gas pipeline. It stretches 4,200 kilometers from Lunnan in the Tarim Basin in the west to Shanghai in the east, crossing nine provinces and regions. Due to the flammable and explosive nature of natural gas, monitoring of the natural gas pipeline network has become a crucial safeguard and firewall for safe production. However, the pipeline network traverses many high-altitude and desert areas with harsh climates and treacherous terrain, placing high demands on monitoring equipment and power supply systems. For example, the Tarim Basin in Xinjiang, the starting point of the natural gas pipeline network, is an extremely cold region with very high altitudes. Winters here are exceptionally cold, with year-round snow and ice cover. Average temperatures are often between -20°C and -25°C, with minimum temperatures reaching -50°C.
The gas transmission network is controlled by automated equipment. In many cases, the power grid cannot cover the area, so batteries are required for power supply. These devices often have very strict power consumption requirements. For example, the average operating current of a gas remote monitoring terminal is only a few milliamps. This necessitates the extremely low power consumption of the intelligent battery system itself to extend battery life and reduce the frequency of equipment maintenance. Furthermore, the equipment is distributed along long gas transmission lines, with distances from management stations to work sites exceeding several hundred kilometers, typically requiring a 4-5 hour drive. Replacing batteries in such situations is very inconvenient. However, the gas monitoring terminals and equipment operate continuously; if forced to shut down, low battery power could lead to serious accidents, causing significant loss of life and property. Therefore, the BMS (Battery Management System) must have a reliability monitoring function to scientifically schedule battery replacement and maintenance based on remaining battery power, thereby improving equipment maintainability.
Specific solutions:
Based on the above application background and requirements, a design method for an intelligent battery system for powering a gas remote monitoring terminal on a given day is proposed. The system requirements are as follows:
(1) The nominal output voltage of the smart battery is 14.2V, the output voltage is 16.8V under full load, and the battery capacity is 20Ah.
(2) Suitable for extremely cold and ultra-low temperature environments. The lower limit of the application temperature is -40℃, and the upper limit is 55℃.
(3) Under extremely cold (-40℃) conditions, the battery discharges at a standard multiplier (0.2c) with a power of more than 75% of its room temperature capacity.
(4) The system is required to have ultra-low power consumption, with an average operating current of less than 400uA at -20℃.
(5) It has a full range of protection functions, including overcurrent, overcharge, over-discharge, over-temperature and short circuit protection.
(6) The system has a relatively accurate power estimation function, and the remaining working time is estimated based on the actual power consumption of the instrument. It can also resist the effects of temperature and aging.
(7) The system can record anomalies, communicate with the host computer, and issue warning signals for anomalies and insufficient power.
