The Techco-Economic Analysis Of Combined Cophase Traction Power Supply System

High-speed and heavy single-phase traction load aggravates the problem of voltage unbalanced to power system, cophase traction power supply system based on kinds of connection form can eliminate the influence of problems mentioned before, but the investment is great in the engineering application. To reduce the cost, scholars have proposed the combined cophase power supply system. The new system is changed greatly in structure, technology and economy.This paper chooses the single-three-phase combined cophase power supply system which is suitable for the reformation of old line and single-phase combined cophase power supply system which is suitable for the construction of new line as research objects. Firstly, this paper respectively discusses the balance transform conditions and the calculation method of compensation current in compensation device based on the structure of two kinds of system and presents the differences between the new systems and the early engineering cophase power supply system in the aspect of capacity configuration, transformer capacity utilization, electrical phase setting and compensation device structure. Then this paper designs the capacity of TT and CPD based on a real line, discusses the load change of devices under two kinds of operation, then establishes loss model of compensation device, and calculates the loss produced by combined cophase traction power supply system when it operates different mode, and analyzes the proportion of each modules’loss in the system.Finally, in order to assess the financial benefits, this paper uses an example of traction substation reformation to discuss the difference in income and losses between combined cophase traction power supply system and interphase power supply system, quantify investment and benefits and give the feasibility of the scheme. Then it uses an example of traction substation building to discuss the difference in income and losses between the combined cophase traction power supply system and early engineering cophase power supply system. From the viewpoint of engineering economics, this paper discusses the advantage of combined cophase traction power supply system.