An Approach to Improve System Performance in the Vehicle-Grid System Using Sliding Mode Control Under Multiple Operation Conditions

Yuting Zhang,Tao Chen,Qixiang Yan,Zhigang Liu,Siqi Wu

doi:10.1109/access.2020.2965215

Yuting Zhang, Tao Chen + Show 3 more

Open Access

https://doi.org/10.1109/access.2020.2965215

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Abstract

To improve the performance of vehicle-grid system under multiple operation conditions and suppress the low-frequency oscillation (LFO) in electrified railways, this paper proposed a control strategy of electric multiple units (EMUs) traction line-side converter (LSC) based on sliding mode control (SMC). First, the accurate model of EMUs is established and then the mathematical model of it in the d-q frame is derived. Then, the application of sliding mode variable structure control strategy in the LSC of EMUs is presented in detail, which includes the design of outer loop voltage sliding mode surface and inner loop current control law. Moreover, the control performance for EMUs based on SMC and traditional linear proportional integral (PI) control is compared under multiple operation conditions in the case of one traction drive unit of EMUs and multi-EMUs, respectively. Finally, experiments are implemented on the hardware in the loop simulation platform based on software StarSim. The experiments results show that, compared with PI control, SMC owns better control performance, such as the lower total harmonic distortion of traction line-side current under multiple conditions, lower voltage fluctuation when braking occurs, better anti-interference ability with the change of system parameters, and can effectively suppress the LFO occurs under operation mode.

Highlights

In recent years, high-speed railways have developed rapidly, and the alternating current-direct current-alternating current (AC-DC-AC) trains have been vigorously developed
APPLICATION OF SLIDING MODE VARIABLE STRUCTURE CONTROL STRATEGY IN THE line-side converter (LSC) OF electric multiple units (EMUs) Ideally, when sliding mode control (SMC) is adopted, if the state point of the system runs in the area near the switching surface, it will be attracted to the area and move according to the designed sliding surface
THE SIMULATION COMPARISON OF CONTROL PERFORMANCE The simulation models of EMUs based on SMC and proportional integral (PI) control are built in Matlab/Simulink, respectively

Summary

INTRODUCTION

High-speed railways have developed rapidly, and the alternating current-direct current-alternating current (AC-DC-AC) trains have been vigorously developed. In [11]–[13], the inverters and the motors are all equivalent to linear resistances, since they are in inoperative states, which makes the accuracy of system model very poor These papers only consider the LFO that occurs when multi-EMUs rise their pantographs at the same time, but do not consider that when EMUs are under operation mode. To improve the performance of vehiclegrid system under multiple operation conditions, this paper applies SMC in the control of the LSC of CRH3 EMUs. The main contributions are presented as follows. It is verified that SMC can effectively suppress the LFO occurring when EMUs run in multiple operation conditions.

MODEL OF ONE TRACTION DRIVE UNIT OF THE EM

THE SIMULATION COMPARISON OF CONTROL PERFORMANCE

Findings

CONCLUSION