Research On The Universal OCC APF-VAR Designed For The Railway Power Networks

ABSTRACT:With the rapid development of the electrified railway in our country, more and more electric locomotives were introduced in the net. On the traction power supply system, the electric locomotive is a harmonic source with rich harmonics. These harmonics will harm the equipments and the traction network seriously, which will threat the security and reliable operation of the whole power system. Considering the harmonic characteristics of the traction, the establishment of a general-purpose hybrid active power filter can optimize the power quality for the railway network, which has all-important significance to improve the operation efficiency and reliability of the railway network. The main contents in this paper are summarized as below:At first, the composition of the electrified railway was analyzed. The analysis of the working principle of the rectifier for the electric locomotive and the harmonic characteristics for the corresponding net-work current, provide the theoretical basis for the post-design of the system structure.Secondly, the working principle and the control strategies of the APF were put and studied. Above all, this paper focused on the researches on the One Cycle Control. Among the OCC's realization ways, this paper made the princile and simulation analysises of several typical ways, which provides a basis for the picking the APF with the combination of the phase principle and the OCC as the control strategy.Again, considering the harmonic characteristics of the traction, and the comparison consequences of various hybrid active power filter topologies'performances, determining to use the Injection Type Hybrid Active Power Filter to optimize the railway network's power quality. The injection branch can keep the APF no-undertaking or less-assuming the fundamental voltage and fundamental current, so as to reduce the capacity of the APF; another, adopting the HAPF can overcome the respective faults of the APF and the PPF, and can achieve reciprocal advantages.Finally, choosing the proper parameters for the system module and the control strategy for the APF, making simulation verified the validity of the circuit. The whole design realizes the compensation of the harmonics and the reactive power successfully.