| The Chinese electric railway has been quickly in the past decade.It is a new situation that one traction substation(TSS)will take the responsibility that supplies more railway lines in a local area,and it is called hub TSS.Different from common TPSS,more railway lines were connected on a bus of hub TPSS.The hub TPSS was caused more resonance points when the distributed capacitance and inductance of each railway line match with inductive power equipment.These resonance points will cause more serious harmonic resonance problem.On the other hand,more different drive-mode of electric locomotives or electric multiple units run on the hub TPSS.Due to harmonic characteristic of train is different,more complex and serious harmonic problem were caused when large number different drive-mode train runs interactively on the system.Therefore,new resonance and harmonic problem of hub TPSS because of multiple railway lines and different drive-mode train,and it was easily cause breakdown power equipment and threaten safety railway operation.It is necessary study about the resonance characteristic,harmonic characteristic and harmonic suppression in the hub TPSS.Dealing with the above issues,the whole mathematical model of Hub TPSS had been established according to topology and electoral parameter of hub TPSS.The supply line model between hub TSS and multiple railway lines was considered.The model of hub TPSS was a research basic of that paper.Based on the whole system model,the resonance characteristic of hub TPSS had been analyzed.It is researched that the influence of different factors on the hub TPSS,such as,railway lines,traction transformer,train,and so on.The resonance sensitivity of hub TPSS was calculated,and the most sensitive component was obtained.The analysis results show that the two types new resonance phenomenon was shown in the hub TPSS,the primary resonance of one resonance point located in low-frequency region and the resonance band of multiple resonance points centered in a high-frequency region.The primary resonance was significantly impacted by hub traction transformer,and the resonance band was significantly impacted the equivalent impedance of train.Based on the measured harmonic current data of different drive-mode train and the hub TPSS model,the harmonic characteristic of hub TPSS was studied on different operation situations by harmonic power flow calculation mothed.The analysis result show that harmonic problem of hub TPSS was constituted that the different frequency characteristic harmonic problem was produced by different drive-mode train and the harmonic resonance problem was produced by the primary resonance and resonance band of hub TPSS match with harmonic current of trains.According to above analysis results of the resonance characteristic and harmonic characteristic of hub TPSS.The characteristic of five types common filter was analyzed,and the hub TPSS impedance-frequency characteristic also be discussed when these filters was installed in system.Two types harmonic suppression scheme were designed,and were evaluated through filter efficiency and equipment cost.The result show that the harmonic suppression of the combination of C-type and single tuned filter was applied for mitigation harmonic problem of hub TPSS and promoting filter efficiency. |
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