Study on adaptive optimal control of CRH5 EMU traction PWM rectifier
To address the stability issues of the pulse width modulation(PWM)rectifier in the CRH5 Electric Motor Unit(EMU)primary traction circuit under traction grid voltage oscillations of railway catenary,a parameter adaptive optimization control strategy based on active disturbance rejection control(ADRC)was proposed.The strategy was built on the dq double-loop control structure applied in CRH5 by using the fastest comprehensive fal function for the inner current loop and adaptively adjusting the control response and the control value to the deviation variation.Based on the state space equations,a first-order linear self-disturbance voltage outer loop controller was constructed to observe and track the system disturbance.The controller's ability to estimate and compensate for external disturbances was improved,and the controller's adaptability to changes in the coupling characteristics of the vehicle network was enhanced.The performance of PID-based dq current control and parameter self-adaptive optimal control was compared and analyzed by Matlab/Simulink.The simulation results reveal that,during the start-up process,the DC output voltage overshoot of the rectifier is minor with the parameter self-adaptive optimal control strategy.Moreover,when dealing with traction grid voltage oscillations,the steady-state error of DC output voltage after recovery is only 1/10 of the required index,indicating stronger anti-interference ability.To further verify the anti-disturbance effect of the controller against grid voltage low-frequency oscillations,a train-grid cascade coupling model was built on the RT-LAB experiment platform to compare and analyze the grid voltage waveform under the two control strategies.The results demonstrate that the parameter self-adaptive optimal control strategy can better adapt to deal with the disturbance caused by multiple high-speed trains simultaneously connected to the grid and can suppress significant oscillations,the parameter adaption feature of the fal current loop can improve the dynamic characteristics of the controller by adjusting the controller's response based on the transient error,and its control parameters have a wide adaptive rsange and are easy to adjust.
CRH5 electric motor unittraction PWM rectifierADRCtraction grid voltagelow frequency oscillation
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