Capacity Optimization And Multiunit Design For Power Quality Compensation Systemof V/v Traction Power Substation

China's transportation industry with the high-speed development of economy as well as the rapid development of constantly,is the important component of the national economy,and the railway has a pivotal position in the transportation industry,and are developing rapidly,especially more popular high speed rail transport at present.With the high-speed electrified railway development at the same time,it brings some of the power quality problems also be focused on,not only does these power quality problems affect the traction power supply system also threaten the safe,stable and economic operation of the public power grid.Therefore,effective and economical solutions must be taken to ensure the safety of the power system stability.For these quality power problems of the traction power supply system based on V/V traction transformer,in this paper,the power quality compensation system is researched mainly as follows:A low-cost hybrid power quality management system is researched for the negative sequence and reactive power compensation of V/v traction power supply system,which consists of a railway power conditioner with a static var compensator to take the advantages of both active and passive compensation technologies.In order to precisely calculate the optimal compensation capacity in real time and under different working conditions,the principle of hybrid compensation structure is analyzed.The active current ratio(KI)of two arms at secondary side,the active power compensation coefficient(?)and the negative sequence reactive power compensation angle(?)are introduced to carry out the theoretical analysis and derive the formula of optimal negative sequence compensation.The relationship between ? and ? is analyzed at a certain degree of negative sequence voltage imbalance,the relationship between active power compensation and reactive power compensation is derived,and a compensation scheme is proposed to optimize its capacity,which without the prior off-line calculation,can online calculate the optimal compensation capacity precisely in real time according to the loads of two arms.The results of case calculation and simulative analysis confirm the correctness and economy of the proposed scheme.At the same time,to solve the common electrified railway power quality problems and the high speed and heavy load locomotives bring more serious negative sequence problem with traction network,we studied parallel multiunit RPCstructure of power quality comprehensive compensation system based on the V/V traction transformer,it can greatly reduce switching frequency to reduce loss and fever,reduce the harmonic content of output waveform,and can to enhance the overall capacity of the device,easy to modular application in parallel multiunit RPC structure of power quality compensation system.In this paper,we studied simulation platform construction,and established the mathematical model,introduced the reference compensating current signal detection and calculation,analyzed the two kinds of control strategy based on PI controller,which in parallel fourfold RPC compensation system.The results of simulative analysis confirm the good compensation effect and superiority of the parallel multiunit RPC compensation system.