Figure 4 - uploaded by Haitao Hu
Content may be subject to copyright.
Source publication
The proliferation of the new high-speed train has resulted in significant distortions in network voltage and current in both traction power supply system (TPSS) and the connected power system. The nonlinear and dynamic natures of the modern trains make the calculation and evaluation of such power quality (PQ) problems quite a difficult work. The ty...
Context in source publication
Context 1
... HSTs have high power factors during operation under the rated power demand configuration. Figure 4 illustrates the trend of power factors with different active power demands. On can see that the power factor is low only when the output power is in a low power demand region (below 1/8 rated traction power), and it is close to 1 with the traction or braking power larger than 500 kW. ...
Similar publications
An AC-DC-AC topology based on multi-converter is proposed in this paper. It can match the capacity of the converter for high voltage and large power applications. This structure is not only suitable for solving the power quality problems of electrified railways, but also has its own superiorities. Its architecture and advantages in the traction app...
Due to the attractive advantages such as modularity, scalability and excellent power quality of modular multilevel converter (MMC), converters based on MMC could be a promising alternative solution for traction transformer. A novel MMC-based advanced co-phase traction power supply system is proposed in this paper to solve power quality issues and e...
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 neut...
The catenary is an important part of the railway power supply system, and the good health of its key components is an important condition for the operation of high-speed trains. Due to the complex composition of catenary components and the large size difference between components, it is very difficult to implement the positioning and detection of a...
This study does research on resonance and harmonic transmission problems in a new continuous cable traction power supply system (CCTPSS), CCTPSS can realise long‐distance co‐phase power supply and effectively reduce phase separation and is applicable for extended power supply in areas with the weak power grid. Firstly, the system structure is intro...
Citations
... These systems can be categorized based on the overhead catenary type, distinguishing between uncomplicated 1 × 15/25 kV and autotransformer-dependent 2 × 15/25 kV systems [7,8]. However, AC ERSs encounter difficulties related to power quality (PQ) concerns, elevated expenses, and diminished efficiency [9][10][11]. Notably, problems like voltage/current unbalance, voltage drops, power factor issues, and various harmonic distortions are significant concerns in AC ERSs [12]. ...
In recent years, there has been increasing interest in integrating the smart grid concept into railway networks, which has been driven by the need to enhance energy efficiency and reduce air pollution in such energy-intensive systems. Consequently, experts have actively sought innovative solutions with which to tackle these challenges. One promising strategy involves integrating renewable energy sources (RESs), energy storage systems (ESSs), and electric vehicle charging stations (EVCSs) into current electric railway systems (ERSs). This study begins by examining the concept of implementing smart grids in railway systems through bibliometric analysis. It then delves into the realization of a hybrid railway microgrid (H-RMG) designed to enhance power flow capacities, improve energy efficiency, and address power quality issues in traditional AC railway networks. This paper introduces various future AC–DC-coupled hybrid railway microgrid (ADH-RMG) architectures centered around a shared DC bus acting as a DC hub for upgrading conventional AC railway systems utilizing interfacing static converters. Through an exploration of different possible ADH-RMG configurations, this research aims to offer valuable insights and a roadmap for the modernization and reconstruction of existing railway networks using smart grid technologies. The integration of RESs and EV charging infrastructures within the ADH-RMG concept presents a promising pathway toward establishing more sustainable and environmentally friendly railway systems.
... For TSSs with unique line parameters (such as long slopes), the backflow RBE can be as large as 20%. On the other hand, backflow RBE aggravates PQ issues (such as imbalance and harmonics) and catenary voltage fluctuation [5], [6], [7], [8]. In extreme conditions, sustained downslope operation of trains injects ample RBE into the catenary, resulting in notable voltage swell and even braking failure [8]. ...
Regenerative braking energy (RBE) utilization plays a vital role in improving the energy efficiency of electrified railways. To date, various power flow control-based solutions have been developed to recycle the RBE for utilization within railway power systems (RPSs). In this paper, an overview of the state-of-the-art power flow control-based solutions for RBE utilization in AC electrified railways is presented. It provides a technical analysis of four primary power flow control-based solutions for RBE utilization, including power sharing-based, energy feedback-based, energy storage-based, and composite solutions. The critical architectures of power flow conditioners for each solution are analyzed in depth. Meanwhile, the power flow control strategies for these solutions are reviewed from the perspectives of power flow management and converter control. From the industrial point of view, the critical challenges associated with fault protection, economy, and environmental impact are discussed. In addition, future trends are comprehensively elaborated from internal and extended improvements. This comprehensive review provides an insightful understanding of the technology readiness, constraints, and perspectives regarding the power flow control-based RBE utilization in electrified railways, contributing to bridging the gaps between academic research and industry implementation.
... Additionally, the RIPFC system should: (i) be sized large enough to enable both of the above actions and (ii) improve the voltage level on both sectors (when loaded) compared to what would happen in conventional feeding. The fulfilment of these objectives is done with regard to other important requirements: the voltage magnitude, harmonic content and other disturbance levels should be met at all times [20,21]. The control strategy should be adapted to allow double-side feeding whenever it is useful and whenever it can bring benefits compared to the conventional situation. ...
This paper gives an overview of the operating characteristics of the railway interline power flow controller (RIPFC) regarding the capability of transferring active power between two sections of an electrified railway line separated by a neutral zone and proposes its use for compensating the power factor at the substation instead of regulating the voltage level at the neutral zone. The basic analysis is based on simplified steady-state models for the energy supply architecture, while detailed time-domain simulations are used for more realistic tests. The paper mainly focus on active power balancing between two neighbouring substations and the global losses in the system. Other functionalities of the RIPFC system are also analysed, like reactive power compensation at the substations. The paper presents the main operating principles of the system, shows results for some representative scenarios (generic and reduced) and discusses the results. The most relevant conclusions are related to substation active power balancing and peak shaving, power factor compensation in the substation, voltage stability at the neutral zone and system power losses.
... The filtering performance of an active filter depend on its control strategies including the reference current extraction [26]- [29], DC-link voltage regulation [30], current control [31], [32], and synchronization [33], [34]. Nevertheless, active filters are more frequently used in high-speed railway (HSR) because HSR produces uncertainty of high-frequency harmonic distortions [13], [35] and harmonic resonance [14], [36] which can cause the transient instability of the high-speed train (HST) tractive drive system and disrupt the operations of sensitive devices [37]. ...
span lang="EN-US">The extensive use of power electronic converters in the third rail system increases the harmonic distortions on the rail electrical feeding systems. Electrical machines and transformers could be overheated causing premature failures of the devices. It is therefore important to address the harmonic distortions on the electrical networks during real-time operation, which includes the degraded operation, not just the normal operation. In this paper, the harmonic distortions of a third rail system are investigated using electrical transient and analysis program (ETAP) simulation software. Four operating scenarios, namely the normal operation and three degraded operations, are considered in the studies. The degraded operations occur when one of the bulk supply transformers or 33 kV feeders is out of service. The findings of the studies showed that the 11<sup>th</sup> and 13<sup>th</sup> order harmonics are the dominant harmonic orders due to the use of 12-pulse rectifiers on the third rail system. Single-tuned harmonic filters are designed and placed in the 33 kV feeders to mitigate the individual voltage harmonic distortion (IHD<sub>v</sub>) and the total voltage harmonic distortion (THD<sub>v</sub>) so that it is within the statutory of IEEE 519:2014.</span
... China's high-speed rail operation consumes about 80 billion MWh of electricity annually, and numerous electricity is consumed during the operation. Traction load (Yang et al. 2019), easily affected by operating conditions, weather conditions, and passenger capacity, is a particular impact load with strong randomness (He et al. 2016). Data mining belongs to a hot study topic in artificial intelligence and databases. ...
Dynamic traction load classification and cluster analysis play an important guiding role in high-speed rail load forecasting. This study classifies numerous measured traction load data after analyzing the dynamic characteristics of the load during typical operation to predict the dynamic load of high-speed rail traction substations accurately. The K-means clustering method is affected by the location of the initial clustering center, which is prone to cause the problem of inaccurate clustering results. The study proposes a sine cosine-K-means (SCA-K) hybrid algorithm for dynamic traction load classification. The sine cosine algorithm (SCA) can dynamically search for the optimal global solution by simulating the outward fluctuation of the sine and cosine functions interactively. The SCA is adopted to optimize the initial classification status. The K-means algorithm is simple in structure, clear in meaning and fast in computation. A combination of the above two algorithms is applied to perform dynamic traction load classification. The case study is to classify the dynamic traction load of a traction substation and compare the classification effect with the other four algorithms. The simulation results show the silhouette coefficient, cluster center, running time, and other results of the SCA-K and the other four algorithms. The proposed SCA-K has a 1.24% higher silhouette coefficient than the best of other compared methods. Compared with the other four algorithms, SCA-K has a superior clustering effect and operational stability and can improve the classification accuracy of traction load.
... It should be acknowledged that discernibility was based years ago on substantially different power conversion architectures of the examined appliances, whereas for electrified rolling stock, the range is quite limited. Old AC locomotives were based on diode and possibly thyristor rectifiers [16], wheres modern ones are all equipped with four-quadrant converters (4QCs) [17][18][19]. Such loads differ from home appliances, making many WS features non-informative, as will be shown in this work (see Section 4.1). ...
... There has been progress in power conversion, i.e., providing faster and more efficient converters, with more complex patterns of emission and distortion occurring over wider frequency intervals [17][18][19]. At the same time, electric transportation is reducing headway, necessitating faster dynamics and resulting in trains more densely arranged along the railway lines [40]. ...
Non-intrusive load monitoring takes place in residential and industrial contexts to disaggregate and identify loads connected to a distribution grid. This work studies the applicability and effectiveness for AC railways, considering the highly dynamic behavior of rolling stock as an electric load, immersed in varying contexts of moving loads. Both voltage–current diagrams and harmonic spectra were considered for identification and extraction of features relevant to classification and clustering. Principal components were extracted, approaching the problem using principal component analysis (PCA) and partial least square regression (PLSR). Clustering methods were then discussed, verifying separability performance and applicability to the railway context, checking the performance by means of the balanced accuracy index. Based on more than one hundred measured spectra, PLSR has been confirmed with superior performance and lower complexity. Independent verification based on dispersion and correlation were used to spot relevant spectrum components to use as clustering features and confirm the PLSR outcome.
... (1) Background current harmonic are generated by exacerbated harmonics injection by electrical components linked to the utilities electricity system, and are typically less than 20pu, i.e. 5-, 7-, 11-, and 13-th harmonics [8,9]. They can be monitored sans transportation in a novel RES. ...
Due to the harmonics insertion from of the asymmetric electric engine, particularly high / elevated / sizable trains, torque ripple and chromatic resonant difficulties have been commonly documented in railway electrification systems (RESs). We investigated the imbalance and switching frequency caused by a neighborhood transmission system, as well as their effects and mitigation policies, in this work. The varying levels of deformation in the supplying program's input characteristics can present a hazard to the propulsion loads. The many
... In the scientific literature, the PQ subject has been covered for more than ten years: many types of different events have been recorded and catalogued, and many measurement systems and algorithms devoted to the classification of these phenomena have been developed [2][3][4][5][6][7][8][9][10]. ...
This paper analyzes the impact of typical DC transient events occurring in railway grids on the frequency performance of instrument transformers (ITs) installed onboard trains and in AC substations for power quality (PQ) applications. PQ monitoring in railway systems is an issue of great interest because it plays a key role in the improvement of energy efficiency. The measurement chain for the PQ measurements, at 15 kV at 16.7 Hz and 25 kV at 50/60 Hz, commonly includes ITs to scale the voltage to levels fitting the input of the measurement units. Nevertheless, the behavior of ITs in the presence of PQ phenomena represents an open issue from a normative point of view, even for those installed in conventional AC power supply systems. In this context, the paper presents a possible definition of DC transient disturbances test waveforms, a measurement procedure, and a setup to assess the impact of these disturbances on the harmonic performances of ITs for railway systems. Preliminary experimental tests carried out on two commercial ITs under wide ranges of variation for the amplitude and the time duration of DC disturbances show that, in some cases, the error introduced in harmonic measurements can exceed 100%.
... Nowadays, using railway networks, especially 2 × 25 kV autotransformer type electric traction systems, is increasing in some countries such as Spain, France, Belgium, Italy, Netherland, Russia, etc. [1]. So the power demand for the traction systems is also increasing, which in turn leads to more current unbalance as well as more reactive power consumption [2]. In [3], while the traction vehicle (with three-phase induction motors) is operated, the effects of the operation on power quality in a 110 kV transmission network were studied. ...
Electric train system is a very large load for the power network. This load consumes a large amount of reactive power. In addition, it causes a massive unbalance to the network, which results in many problems such as voltage drops, high transmission losses, reduction in the transformer output ability, negative sequence current, mal-operation of protective relays, etc. In this paper, a novel real-time optimization approach is presented to adjust the static VAR compensator (SVC) for the traction system to realize two objectives; current unbalance reduction and reactive power compensation. A multi-objective optimization technique entitled non-dominated sorting genetic algorithm (NSGA-II) is used to fulfill the regarded objectives simultaneously. A comprehensive simulator has been designed for electric train network modeling that is able to adjust the parameters of SVC in an optimum manner at any time and under any circumstances. The results illustrate that the provided method can efficiently reduce the unbalancing in current as well as supply the demanded reactive power with acceptable precision.
... Electrified railways, DC or AC, must deal with several power quality issues, either in the railway subsystem itself and in the transmission/distribution system operator (TSO/DSO) supply [7][8][9][10]. In the past, some passive solutions helped to alleviate these issues but their performance was dependent on different operation parameters and has poor dynamics. ...
... br [8] ? br [9] ? br [3] = br [2]). ...
The high dynamic power requirements present in modern railway transportation systems raise research challenges for an optimal operation of railway electrification. This paper presents a Monte Carlo analysis on the application of a power transfer device installed in the neutral zone and exchanging active power between two sections. The main analyzed parameters are the active power balance in the two neighbor traction power substations and the system power losses. A simulation framework is presented to comprise the desired analysis and a universe of randomly distributed scenarios are tested to evaluate the effectiveness of the power transfer device system. The results show that the density of trains and the relative branch length of a traction power substation should be considered in the evaluation phase of the best place to install a power transfer device, towards the reduction of the operational power losses, while maintaining the two substations balanced in terms of active power.
