| Electrified railway is the main artery of economic and society development, and the security and stability of locomotive traction power supply decides the normal operating of electrified railway. Because the electric locomotives are supplied by single phase power sources obtained from rectifiers, the power quality problems (such as negative sequence, harmonic and reactive), which are caused by electric locomotive, seriously threat the safe and stable operating of traction power supply grid and upper power system. Hence, valid power quality integrated compensation methods for electrified railway should be adopted to enhance the security and stability of locomotive traction power supply system.Under the support of sub-project of state science and technology support program named "integrated compensation and harmonic suppression technology for high-speed railway power supply system", this paper studied power quality integrated compensation methods of two traction power supply systems, which are AC-DC power locomotive power supply system (conventional electrified railway) and AC-DC-AC power locomotive power supply system (high speed electrified railway). The power quality integrated compensation topology, real-time detection method of power quality compensation references (negative sequence, harmonic and reactive) and control strategy were studied in this paper. The main work and innovations of this paper are listed as follows.(1) An integrated compensation topology and control strategy for AC-DC power locomotive power supply system was presented, the rating of active compensation part was effectively reduced, and the overall cost of the compensator was reduced. The presented topology is composed of active equipment—railway static power conditioner (RPC) and reactive equipment—thyristor switched capacitor (TSC). The operating principle, characteristics of cost and harmonic amplification of this compensator were analyzed, and the overall control strategy and its realization methods were presented, which realizes the coordination control between RPC and TSC. Simulation and experimental results demonstrate the proposed compensation topology and its control method can reduce the compensation rating of RPC, and achieve a good integrated compensation effect.(2) The negative and harmonic compensation principle for high-speed railway power supply system with a three-phase V/V traction transformer was analyzed, and negative sequence and harmonic control method for high speed railway power supply system based on railway static power conditioner was presented. The principle to compensate negative-sequence currents for high-speed railway power supply system with a three-phase V/V transformer was explained by using the vector analytical method, and a strategy to provide the compensation references for negative-sequence and harmonic currents is proposed. Also, a method to separate active current, reactive current and harmonic current references from the total negative-sequence and harmonic current references was given.(3) A hybrid integrated compensation system for high-speed railway power supply system and its compensation strategy were presented, the compensation rating of this compensator was optimized, and a good negative compensation effect was achieved with relatively low compensation capacity. To aim at the big negative sequence current of high-speed railway power supply system, a hybrid integrated compensation system composed of railway static power conditioner (RPC), thyristor controlled filter (TCF), and thyristor controlled reactor (TCR) was proposed. The topology and operation principle of proposed compensation system were investigated. Based on the analysis of relationship between the compensation rating of RPC, TCF and TCR and negative sequence index, and considering the operating cases of electric locomotives, a compensation rating design method of the sub-system of the proposed hybrid compensation system and an expert reasoning control strategy for the proposed system were presented. A method to generate the compensation references for the compensator and a control method to realize the compensation strategy were presented. Simulation results demonstrates the proposed hybrid compensation system for high-speed railway power supply system and its compensation strategy can achieve a good negative sequence compensation effect under different operating cases of electric locomotives.(4) A negative sequence compensation system based on two-phase three-wire converter for high speed railway power supply system and a compound control method for this compensator were presented. The power switch number of the proposed compensator was decreased, and the current control effect of the compensator was enhanced. In order to simplify the main circuit of compensator and save the cost, a negative compensation system composed of two single-phase step-down transformers and a two-phase three-wire converter was presented. Based on the established electric model of two-phase three-wire converter, the operation principle of two-phase three-phase converter was analyzed, and the the characteristic of two-phase three-wire converter can be treated as two single-phase converter combining was discovered. In order to enhance the response speed and steady precision of current tracking control, a compound control method composed of hysteresis loop control and generalized integral control was presented. Simulation and experimental results confirm the validities of the negative sequence compensator for high speed railway power supply system based on two-phase three-wire converter and its compound control method.(5) The parameter design method for main components of RPC was investigated, and the design technology of simulative experimental setup was introduced. As RPC is a typical compensator of the integrated compensators for electrified railway power supply system, the parameters selection method of RPC main components was investigated. Taking the security and control performance optimization of the setup as the condition, design methods of turns ratio and rating of single-phase step-down transformer, AC output inductance and DC-link capacitor were presented. The structure of RPC simulative experimental setup was introduced, and also the hardware and software design methods of the control system in the experimental setup. The zero-crossing detection circuit, before sampling filter circuit, sampling circuit, over-voltage over-current protection circuit, communication circuit and other peripheral controller circuit were introduced. The main program, interruption program and communication program design method were also gived. The parameters design method and the design technology of simulative experimental setup provide the experimental testing condition for academic research results, and will also lay the foundation for engineering prototype trial. |
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