Control method of urban rail transit energy storage system based on pi loop to adjust discharge threshold

Abstract

The invention relates to an urban rail transit ground lithium ion battery energy storage system control method capable of adjusting a discharge threshold value based on a PI ring and belongs to the urban rail transit control field. According to the method, the actual discharge threshold value of network voltage is calculated; when a train is towed, the network voltage of a traction network drops,when the network voltage falls below discharge threshold voltage, the traction network is connected with a high-power DC / DC device of a lithium battery energy storage system so as to enter a dischargevoltage loop, and therefore, the lithium battery energy storage system performs discharging to maintain the voltage of the traction network near the discharge threshold voltage; and when the train isbraked, the network voltage of the traction network rises, when the network voltage rises above a charge threshold value, the traction network is connected with the high-power DC / DC device of the lithium battery energy storage system so as to enter a charge voltage loop, and therefore, the lithium battery energy storage system performs charging to maintain the voltage of the traction network nearthe charge threshold value. With the method of the invention adopted, the problem of SOC offset caused by existing fixed threshold control can be solved, and the lithium battery energy storage systemcan work near the SOC value of a point where the power of the system is the highest.

Description

technical field [0001] The invention relates to an energy-saving technology for urban rail transit, in particular to a control method for an urban rail transit ground lithium-ion battery energy storage system based on a PI loop to adjust a discharge threshold. Background technique [0002] With the development of urban rail transit, its power consumption has also increased rapidly, and the energy-saving operation of urban rail trains has become an urgent problem to be solved. Urban rail trains are generally driven by AC motors. When the train brakes, the motor can work in generator mode to convert the mechanical energy of the train movement into electrical energy. This braking method is called regenerative braking. Since the urban rail traction substation adopts an uncontrolled rectification rectification method, the electric energy generated by regenerative braking cannot be sent back to the AC grid through the traction substation, so most trains now use resistors to dissi...

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a control method for the ground lithium-ion battery energy storage system of urban rail transit based on the PI ring to adjust the discharge threshold, which can solve the problem of SOC offset caused by the existing fixed threshold control, and can make lithium The battery energy storage system works near the SOC value of its maximum power point

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