High-Speed Railway Traction Power Supply System Load Modeling

With the rapid development of China’s high-speed rail, high-speed rail traction power supply system has become one of the important loads of the power system. But high-speed rail traction load, as a large capacity and strong impact of nonlinear load, would cause a series negative impacts on power network, even undermine the safe and stable operation of the power network. In order to adapt to the rapid development of China’s high-speed railway, the study of high-speed rail traction power supply system load modeling is very important to the exact analysis and evaluation of high-speed rail traction power supply system operating status. It is helpful to reduce its impact on the power system and generates great significance in guaranteeing their healthy and coordinated development.On this basis, according to the working principle and load characteristics of the high-speed rail traction power supply system, simulation modeling of EMU traction drive system is studied in this article. And then, parameter identification method is used to carry out the EMU load modeling and traction power supply arm load modeling research.In the aspect of EMU traction drive system simulation modeling, since operating characteristics of the EMU is not only affected by the traction network voltage, but also affected by the line conditions and load, CRH2EMU traction drive system simulation model is established, which is used to make simulation analysis under different operating conditions. On the base of studying EMU control principle of traction braking characteristics and control strategy, CRH2EMU traction drive system simulation model is established. According to the brake deceleration, regenerative braking force and the air braking force are calculated. EMU’s electromagnetic torque and load torque are changed to analog electro-pneumatic composite braking and then the simulation of whole process of traction and braking is completed. Impact of line conditions on EMU is analyzed and the variation of line conditions is imitated through the load torque variation to carry out EMU operation simulation under different line conditions and network voltage fluctuations. The results of simulation show that the parameters of the model are realistic and the model can simulate the real operation of EMU.In the aspect of EMU load modeling, considering that EMU load varies with EMU operating conditions, load and line conditions, CRH2EMU load model is built and the applicability of the model is analyzed. EMU operates as asynchronous motors and asynchronous generator status, respectively, under traction and braking condition. According to the load configuration and features, the use of asynchronous motors with parallel static load model is made to describe the dynamic load of the vehicle group. With the power disturbance data generated from CRH2model under different speed and voltage disturbance, genetic algorithm is utilized to identify the parameters and model generalization ability is studied. Results show that the load model can describe the dynamic load requirements of EMU under traction and braking conditions. Vary some parameters of the load model to reflect the EMU load changes under different load and line conditions. The results show that this method can effectively improve the applicability of the model.In the aspect of traction substation power arm load modeling, taking the fact that traction substation power arm load varies with the CRH2quantity, load and line conditions into account, the traction substation power arm load model is built and the applicability of the model is analyzed. Referred to the existing model method of traction substation load, traction substation supply arm load model is established and the parameters is identified using genetic algorithms. Results show that the model can fit the identification of the sample data well. Vary some parameters of traction substation supply arm load model to adapt to the different requirements of substation load under different geographical conditions.Generally speaking, the load model established in this paper can be realistic to simulate the high-speed rail traction power supply system load characteristics, which is expected to support the theoretical study of the high-speed rail traction power supply system and its impact on the power system analysis.