Compensation of negative sequence for a novel AC integrated power supply system of urban rail transit

Abstract

With the large‐scale increasing demand for passenger transportation, the alternating current (AC) 25 kV traction power supply system (TPSS) of electrified railway is introduced into the construction of urban rail transit in China instead of the direct current (DC) TPSS. In order to suppress the negative sequence current and cancel the neutral section at the exit of traction substation of the AC TPSS, a novel AC integrated power supply system (IPSS) of the urban rail transit based on single‐phase static var generator (SVG) is proposed, which the capacity of SVGs can be further reduced. The topology of the novel AC IPSS is introduced. By defining the constraint factors of negative sequence current and reactive power compensated, the comprehensive compensation model of negative sequence current and reactive power of the novel system is established based on the corresponding standards, which the full compensation and satisfactory compensation can be achieved. The method of determining the compensation scheme and the control strategy are proposed. Taking the actual data as an example, the effectiveness of the compensation scheme is proved. In addition, the correctness of the control strategy proposed is proved by simulation and experiment.

Study on resonance characteristic of continuous co‐phase traction power supply system

“…Taking the current phase of traction load lagging the voltage phase under the traction condition as an example, the power factor is cos 𝜑 L , and the specific compensation principle is shown in Figure 2, U − are opposite in direction, negative sequence is fully compensated when they are equal in magnitude. With the rational design of the reactive currents emitted by three SVGs, the comprehensive compensation purpose of reactive power and negative sequence components may be achieved [10].…”

“…The negative sequence components of the reactive currents emitted by the SVG are, $$\dot I_{{\rm{S}}1}^ - $$, $$\dot I_{{\rm{S2}}}^ - $$ and $$\dot I_{{\rm{S3}}}^ - $$, which are combined into $$\dot I^{\prime}_{{\rm{SL}}}{^ -} $$, $$\dot I^{\prime}_{{\rm{SL}}}{^ - }$$ and $$\dot I_{\rm{L}}{^ -} $$are opposite in direction, negative sequence is fully compensated when they are equal in magnitude. With the rational design of the reactive currents emitted by three SVGs, the comprehensive compensation purpose of reactive power and negative sequence components may be achieved [10].…”

“…However, the CCTPSS proposed in the above references needs to add compensators in all traction substations in engineering application. Therefore, a CCTPSS utilizing static var generators (SVG) for compensation is proposed in [9] and [10], SVG compensates power quality problems by emitting reactive power, this method does not change the active power flow, so only a small number of traction substations need to be selected for centralized compensation. In this paper, the CCTPSS of this structure is used as the background for the resonance analysis.…”

Research on the Influence of Urban Subway on Neutral Current of High-Voltage Substations Along the Line Under Complex Environment

“…However, rail potential cannot always be directly grasped by the power company, especially the operation and maintenance department, and the rail potential is easily affected by the position of the measurement point which makes the method limited. In [12] and [13], the negative rail current was studied, both its suppression and exploitation methods have been proposed. There is a consensus among these studies that the neutral current is related to the frequent starting and braking of train.…”

Study on the electromagnetic ring network in bilateral power supply mode of electrified railway

“…It has a great impact on power systems such as generators, transformers, and relay protection. The safe and stable operation of power system is difficult to be guaranteed [2]- [3]. In order to reduce the impact of negative sequence current, the alternating commutation mode is adopted to connect the traction power supply system to the grid, which is different phases of electric energy fed by different traction substations for load use [4].…”