Research On Control System Of Electric Power Quality Integrated Management System Of Electrified Railway

With the development of electrified railway in our country, the power quality problems, such as the negative sequence, reactive power and harmonic, are still outstanding, not only reduce the power quality of public grid, and cause serious influence on its safe and stable operation. To improve the quality of electrified railway power supply system, and the safety and stability of the public power grid, scholars and engineers have put forward many kinds of active topology, among them, the hybrid railway power quality management system (H-RPQMS) with coupling LC branch, which can reduce inverter port voltage and thus significantly reduce inverter compensation capacity, this makes the H-RPQMS possess the potential for further research and application. To achieve better performance of H-RPQMS, in addition to the reasonable allocation of system parameters, it is very important for the research of the control system. Domestic control research of H-RPQMS is mainly hysteresis current control based on direct current control, its characteristic is integrating control and modulation, fast response speed, small current tracking error, but its engineering adaptability remains to be further improved. Therefore, in this paper, a more flexible H-RPQMS control scheme is an important issue to be solved urgently. The specific work and innovative points of the paper are as follows. On the basis of summarizing the common detection methods, the suitable method is given for the detection of H-RPQMS.Firstly, this paper summarizes the research status of the load characteristics and power quality management of the electrified railway, and introduces several control methods of the current stage inverter; By mathematical deduction, the compensation principle of H-RPQMS is described in detail, the optimal design method of LC coupling branch is given based on the analysis of the port voltage.Secondly, an indirect current control scheme based on H-RPQMS is proposed, which introduces two coefficients k1 and k2 that are used to adjust the pole position of the control object in order to facilitate the design of the control system. The mathematical model is established in the static system. To reduce the complexity of the control scheme, transforming the mathematical model to the synchronous orthogonal dq coordinate system, by implementing the inner and outer loop of decoupling to obtain better control performance. Decoupled current internal loop makes the compensation current follow the reference by PI control, dc voltage and power loop use PI controller.Finally, The H-RPQMS simulation model is built on the MATLAB Simulink platform based on the data of a traction substation measured in the north of Hunan, and verifies the effectiveness of the proposed indirect current control scheme. The steady state performance and transient performance of the whole hybrid railway power quality management system are analyzed in detail.