The autotransformer(AT)neutral current ratio method is widely used for fault location in the AT traction power network.With the development of high-speed electrified railways,a large number of data show that the relat...The autotransformer(AT)neutral current ratio method is widely used for fault location in the AT traction power network.With the development of high-speed electrified railways,a large number of data show that the relation between the AT neutral current ratio and the distance from the beginning of the fault AT section to the fault point(Q-L relation)is mostly nonlinear.Therefore,the linear Q-L relation in the traditional fault location method always leads to large errors.To solve this problem,a large number of load-related current data that can be used to describe the Q-L relation are obtained through the load test of the electric multiple unit(EMU).Thus,an improved fault location method based on the back propagation(BP)neural network is proposed in this paper.On this basis,a comparison between the improved method and the traditional method shows that the maximum absolute error and the average absolute error of the improved method are 0.651 km and 0.334 km lower than those of the traditional method,respectively,which demonstrates that the improved method can effectively eliminate the influence of nonlinear factors and greatly improve the accuracy of fault location for the AT traction power network.Finally,combined with a shortcircuit test,the accuracy of the improved method is verified.展开更多
Abstract-The ineffective utilization of power resources has attracted much attention in current years. This paper proposes a real-time distributed load scheduling algorithm considering constraints of power supply. Fir...Abstract-The ineffective utilization of power resources has attracted much attention in current years. This paper proposes a real-time distributed load scheduling algorithm considering constraints of power supply. Firstly, an objective function is designed based on the constraint, and a base load forecasting model is established when aggregating renewable generation and non-deferrable load into a power system, which aims to transform the problem of deferrable loads scheduling into a distributed optimal control problem. Then, to optimize the objective function, a real-time scheduling algorithm is presented to solve the proposed control problem. At every time step, the purpose is to minimize the variance of differences between power supply and aggregate load, which can thus ensure the effective utilization of power resources. Finally, simulation examples are provided to illustrate the effectiveness of the proposed algorithm.展开更多
The single-phase traction load has essentially an unbalance characteristic at the Point of Common Coupling (PCC), which injects harmonic into the utility grid. In this paper, the effect of harmonic distortion and unba...The single-phase traction load has essentially an unbalance characteristic at the Point of Common Coupling (PCC), which injects harmonic into the utility grid. In this paper, the effect of harmonic distortion and unbalance loading are investigated simultaneously for electrical railway systems. Special traction transformers (i.e. single-phase, V/V, Wye-Delta, Scott, and Le Blanc) are used between the utility grid and the traction load. For analysis, different defini-tions of power factors are considered, which are presented by IEEE Std.1459. The detailed simulation study is made with MATLAB/SIMULINK program to represent the impacts of harmonic components and unbalance loading on the power factor behavior in the Electrical Railway systems.展开更多
Microgrid (MG) systems effectively integrate a generation mix of solar, wind, and other renewable energy resources. The intermittent nature of renewable resources and the unpredictable weather conditions contribute la...Microgrid (MG) systems effectively integrate a generation mix of solar, wind, and other renewable energy resources. The intermittent nature of renewable resources and the unpredictable weather conditions contribute largely to the unreliability of microgrid real-time operation. This paper investigates the behavior of microgrid for different intermittent scenarios of photovoltaic generation in real-time. Reactive power coordination control and load shedding mechanisms are used for reliable operation and are implemented using OPAL-RT simulator integrated with Matlab. In an islanded MG, load shedding can be an effective mechanism to maintain generation-load balance. The microgrid of the German Jordanian University (GJU) is used for illustration. The results show that reactive power coordination control not only stabilizes the MG operation in real-time but also reduces power losses on transmission lines. The results also show that the power losses at some substations are reduced by a range of 6% - 9.8%.展开更多
Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on...Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on and impact current is analyzed systematically in this article. π-type equivalent circuit of feeding section is put forward in the analysis of overvoltage mechanism. Overvoltage and overcurrent model of passing by phase-separation with electric load are also built. Correctness of mechanism was validated by simulation. In addition, the methods to solve the influence on substations, transformers and protection devices in this process are put forward, which provides a new idea on passing by phase-separation with electric load technology.展开更多
针对动车组高速运行带来的牵引供电系统TPSS(Traction Power Supply System)拓扑结构变化引起的谐波畸变动态波动,为评估TPSS的谐波畸变情况,综合考虑动车组运行过程中的牵引计算和牵引供电计算,提出一种考虑行车运行图的TPSS谐波评估...针对动车组高速运行带来的牵引供电系统TPSS(Traction Power Supply System)拓扑结构变化引起的谐波畸变动态波动,为评估TPSS的谐波畸变情况,综合考虑动车组运行过程中的牵引计算和牵引供电计算,提出一种考虑行车运行图的TPSS谐波评估方法。结合行车运行图和动车组牵引计算得到TPSS的牵引负荷特性,建立TPSS动态仿真模型,应用基波潮流和谐波潮流计算结果分析TPSS中各关键位置的实时谐波特性;应用谐波分析结果的最大值、99%概率统计值和95%概率统计值评估TPSS的谐波指标。仿真结果与现场实测对比验证了该方法的有效性,该方法可用于TPSS和行车运行图的设计与优化。展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFB2601500)the Natural Science Foundation of Sichuan Province(No.2022NSFSC0405)。
文摘The autotransformer(AT)neutral current ratio method is widely used for fault location in the AT traction power network.With the development of high-speed electrified railways,a large number of data show that the relation between the AT neutral current ratio and the distance from the beginning of the fault AT section to the fault point(Q-L relation)is mostly nonlinear.Therefore,the linear Q-L relation in the traditional fault location method always leads to large errors.To solve this problem,a large number of load-related current data that can be used to describe the Q-L relation are obtained through the load test of the electric multiple unit(EMU).Thus,an improved fault location method based on the back propagation(BP)neural network is proposed in this paper.On this basis,a comparison between the improved method and the traditional method shows that the maximum absolute error and the average absolute error of the improved method are 0.651 km and 0.334 km lower than those of the traditional method,respectively,which demonstrates that the improved method can effectively eliminate the influence of nonlinear factors and greatly improve the accuracy of fault location for the AT traction power network.Finally,combined with a shortcircuit test,the accuracy of the improved method is verified.
文摘Abstract-The ineffective utilization of power resources has attracted much attention in current years. This paper proposes a real-time distributed load scheduling algorithm considering constraints of power supply. Firstly, an objective function is designed based on the constraint, and a base load forecasting model is established when aggregating renewable generation and non-deferrable load into a power system, which aims to transform the problem of deferrable loads scheduling into a distributed optimal control problem. Then, to optimize the objective function, a real-time scheduling algorithm is presented to solve the proposed control problem. At every time step, the purpose is to minimize the variance of differences between power supply and aggregate load, which can thus ensure the effective utilization of power resources. Finally, simulation examples are provided to illustrate the effectiveness of the proposed algorithm.
文摘The single-phase traction load has essentially an unbalance characteristic at the Point of Common Coupling (PCC), which injects harmonic into the utility grid. In this paper, the effect of harmonic distortion and unbalance loading are investigated simultaneously for electrical railway systems. Special traction transformers (i.e. single-phase, V/V, Wye-Delta, Scott, and Le Blanc) are used between the utility grid and the traction load. For analysis, different defini-tions of power factors are considered, which are presented by IEEE Std.1459. The detailed simulation study is made with MATLAB/SIMULINK program to represent the impacts of harmonic components and unbalance loading on the power factor behavior in the Electrical Railway systems.
文摘Microgrid (MG) systems effectively integrate a generation mix of solar, wind, and other renewable energy resources. The intermittent nature of renewable resources and the unpredictable weather conditions contribute largely to the unreliability of microgrid real-time operation. This paper investigates the behavior of microgrid for different intermittent scenarios of photovoltaic generation in real-time. Reactive power coordination control and load shedding mechanisms are used for reliable operation and are implemented using OPAL-RT simulator integrated with Matlab. In an islanded MG, load shedding can be an effective mechanism to maintain generation-load balance. The microgrid of the German Jordanian University (GJU) is used for illustration. The results show that reactive power coordination control not only stabilizes the MG operation in real-time but also reduces power losses on transmission lines. The results also show that the power losses at some substations are reduced by a range of 6% - 9.8%.
文摘Aiming at the complex electromagnetic transient process of EMU passing by phase-separation with electric load in high-speed railway, mechanism of overvoltage caused by switching off, overvoltage caused by switching on and impact current is analyzed systematically in this article. π-type equivalent circuit of feeding section is put forward in the analysis of overvoltage mechanism. Overvoltage and overcurrent model of passing by phase-separation with electric load are also built. Correctness of mechanism was validated by simulation. In addition, the methods to solve the influence on substations, transformers and protection devices in this process are put forward, which provides a new idea on passing by phase-separation with electric load technology.
文摘针对动车组高速运行带来的牵引供电系统TPSS(Traction Power Supply System)拓扑结构变化引起的谐波畸变动态波动,为评估TPSS的谐波畸变情况,综合考虑动车组运行过程中的牵引计算和牵引供电计算,提出一种考虑行车运行图的TPSS谐波评估方法。结合行车运行图和动车组牵引计算得到TPSS的牵引负荷特性,建立TPSS动态仿真模型,应用基波潮流和谐波潮流计算结果分析TPSS中各关键位置的实时谐波特性;应用谐波分析结果的最大值、99%概率统计值和95%概率统计值评估TPSS的谐波指标。仿真结果与现场实测对比验证了该方法的有效性,该方法可用于TPSS和行车运行图的设计与优化。
