Zhang Dinghua

Application research on wide frequency domain harmonics and resonance suppression on traction network

Wide frequency domain harmonics and resonance often appear in small capacity of traction network while high power, high density, and different kinds of locomotives take power in the same power supply arm. The mechanism of wide frequency harmonic was provided by the analysis of locomotive converter topology and modulation of ac locomotive. The harmonic distribution diversity of different types of locomotive assembly was proved by testing the two typical locomotives. The new compensation scheme including a H-bridge cascaded active power filter (HCAPF) and a high-pass filter (HPF) was invented , The former compensates reactive power and restrains low order harmonics, and the latter absorbs high order harmonics and provides fixed capacitative reactive power. Combining the demonstration project, the parameter design and performance were introduced in detail. The object power quality parameters were compared by the 24 hours data before and after the proposed system put into operation. The results show that the voltage distortion rate average is decreases from 4.324% to 2.934%, and every harmonic voltage is improved obviously. The max volatility of network voltage reduce form 14.5% to 10.7%.

A power quality combined compensation system and its application on three-phase large-power and impulse loads

On account of the capacity of active power filter (APF) is limited, a novel structure of combined compensation system is proposed to solve the question of Jerky loadpsilas power quality, including voltage flicker, harmonic pollution, and power factor low. This combined compensation system is composed of static var compensator (SVC) and active power filter (APF). In this system, the SVC is used for compensating reactive power quickly, as well as for improving three-phase unbalanced degree and negative phase-sequence current caused by impulse load. The APF is used for mitigating harmonics caused by Jerky load and thyristor controlled reactor(TCR). In order to realize decentralized control of SVC and APF, a reasonable topological structure is adopted. The operational principle of system, a new reactive power calculation method and control strategy is presented in detail. The feasibility and validity of the combined compensation system is verified by the waves and data of practical operation.