The Hardware Development Of Data Acquisition System Of Electrified Traction Load Characteristic

In order to deeply study the adverse impacts of electrified railway traction load on public power grid, improve power quality in grids and enhance system stability, the related study on traction load should be done to evaluate the formation mechanism, formation conditions of these impacts. In view of the special nature of the power system, usually the way of computer simulation will be adopted to simulate a variety of conditions of traction load. And accurate simulation model is needed, so the traction load modeling has become a serious problem in power system.The paper introduces that the development of on-line data acquisition system of electrical traction load characteristic to provide effective data for the measurement based method of power system load modeling. On the basis of comparing many structures of data acquisition system and following the requirements of data acquisition system of electrical traction load characteristic, the design of the system based on CPLD and USB technologies will be selected. The system could be used to realize 32 channels and 12-bit data acquisition based on CPLD logic control chip which is at heart of the central control unit, four 8-channel A/D conversion chips, high-speed FIFO chip and USB controller chip with USB2.0 interface., from which the number of chips and the failure risk of system were reduced effectively, the stability and design flexibility of the system were improved. With USB transmission, the stability and adaptability of the system has been further improved; the bottleneck between transmission speed and the number of channels in traditional system has also been settled.The hardware and software design method of the system was detailedly introduced in this paper. The hardware connection and software control between each chip were discussed respectively. The design method of core-subordinate state machine was obtained by using the characters of state machine in the CPLD software design, in which precise and clear control was achieved. The problems of timing control were well solved.The design of the system was optimized through the simulation of the QuartusII software, the optimization advisor tools and all sorts of test of laboratory equipment, which increase the reliability and automatization level of the system. The results from the simulation and tests prove that the system is able to meet the requirement of load modeling in power system.