Research On Flywheel Energy Storage Control System Applied On Rubber-tyred Gantry Crane

In a flywheel energy storage system (FESS), energy is stored in the form of kinetic energy by rotating a mass flywheel at a determined high speed. The energy stored and delivered by the FESS depends primarily upon accelerating and decelerating the speed the flywheel rotor. Developed with technologies such as high specific strength carbon fiber composite materials, magnetic bearings, high performance power electronics, FESS is charactered with extremely high reliability and efficiency, environment-friendly, extended long life and numbers of charge/discharge cycles. FESS has successfully applied in many fields such as military, electrical power, vehicles and aerospace industries. This thesis applies flywheel energy storage system as the energy storage device of the hybrid RTG crane to meet the peak energy requirements of crane when a peak load is used. The FESS not only use the regenerated power of the RTG crane by storing the energy into the high-speed spinning flywheel, but also to feed it back into the power line during both acceleration and regenerative braking, and therefore produces the less fuel consumption and emissions.This dissertation is mainly engaged in the control system and bi-directional converter of the high-speed magnetic bearing FESS applied on rubber-tyred gantry crane (RTG).The energy management strategy of the hybrid RTG, modeling, analysis, control, and hardware fabrication of the FESS are involved in the research.First of all, this dissertation establishes the power demand and power supply model of the hybrid RTG, and analyses the quasi-static model of the hybrid power RTG powertrain system. Afterwards the energy management strategy between the two available power sources is designed and optimized.In the next step, this dissertation establishes the model of the permanent magnet synchronous generator/motor in dq synchronous frame. Based on the topological structure of the FESS, dq synchronous frame equivalent model of FESS both in charging and discharging mode is derived. Upon the dq synchronous frame equivalent model, DC and small-signal AC model of the system is achieved. These models effectively simplify analysis of the FESS. Then, current control strategies of the permanent magnet synchronous machine both in charge and discharge mode of operation is investigated in detail. According to the traditional double closed-loop control strategy, control strategy of the high-speed FESS based on a surface mount permanent magnet synchronous machine (PMSM) with feedforward control strategy both in current loop and DC bus voltage loop is explored in this paper during charging and discharging mode of operations.In the past part of the thesis, the control system and bi-directional energy converter are designed and fabricated with DSP TMS320F28335as the core. Finally, based on discussed model and algorithm of the system, the hardware and software of the system are simulated together in PSIM simulation environment, and the results are presented as a reference to the further research of the kWh FESS.