The Same Phase Of Traction Power Supply Plan Comprehensive Optimization

The main transformer have many connection forms in the cophase traction power supply system. It mainly include four types:the mode based on "Y" form wiring (YNd11); the mode based on the balance transformer wiring (such as Scott, impedance matching balance, three phase change four phase); the mode based on the "V connection (Vv, Vx, Vy); the special transformer (such as not equal sides Scott wiring, not equal sides YNvd wiring, YN2d wiring).If we combine the transformer wiring forms with the compensation modes (passive or active) and balance transform devices, a lot of cophase traction power supply systems are constructed. In order to select a method suitable for China’s high iron development from these many cophase power supply project, this paper mainly do the following efforts.The first, this paper introduced the advantage of the special transformer in using under passive symmetric compensation. But in active symmetric compensation technology, the minimum volume of compensation devices have nothing to do with load connection angle.So it can’t change the economy of the power supply system in active compensation to use the special transformers, inversely, it is desirable to use the conventional transformer whose manufacturing operation is very simple and maintenance technology is very mature.The second, a major investment depends on the investment of the main transformer and the balance transformation device in the cophase traction power supply system using the active symmetric compensation technology. So it is necessary to discuss the main transformer capacity and capacity utilization rate. In the same compensation, this paper Discussesed that the installed capacity of Vv wiring transformer is higher than YNd11and Scott in the cophase traction power supply system constructed three kinds of phase wiring transformer if the total capacity supplied from system is equal. In order to realize the optimization of transformer capacity by adjusting the reactive power compensation degree and negative sequence compensating degrees, this paper also discusses the relationship between three kinds of transformer capacity utilization with the compensation degree. In addition, in order to compare the characteristics of the power supply system constructed conventional transformer including YNd11, Scott, Vv, we can draw the conclusions through the simulation that are established by MATLAB simulation model:These three systems all can eliminate out of balance, filter harmonic, compensate reactive power and negative sequence making the asymmetry single phase load to be a pure resistance sexual three-phase symmetric load for electric power system in full compensation. kinds of characteristic difference is not obvious. The last, From analysising the structure of the balance transform device, capacity utilization, balance sexual, the selection of DC voltage, the control strategies and so on, we can draw the conclusion: the balance transformation device of Back-to-back structure is the most simple; from the side of Capacity utilization, back-to-back structure has more advantage than the three bridge legs structure adopted balance transformation device when reactive power, negative sequence and harmonic have been compensated in full for the cophase traction power supply system; When the traction load contains a lot of reactive power and harmonic, the structure of back-to-back balance transformation device is best in the balance sexual, and the capacity can be made full advantage; the control strategy of back-to-back balance transformation device is the simplest.