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Background Lung cancer is one of the most common malignancies around the world. The lack of early diagnosis and effective treatment strategies contributes to the poor prognosis of patients with lung cancer. Recent studies have implied the role of long non-coding RNAs (lncRNAs) in oncogenesis. The purpose of our study was to identify specific lncRNAs which were correlated with non-small cell lung cancer (NSCLC) and their potential functions. Materials and Methods The global plasma lncRNA profiling was performed using LncPathTM Human Cancer Array, and 11 lncRNAs were then selected for quantitative reverse transcription PCR (qRT-PCR) validation in 138 plasma samples from 69 NSCLC patients and 69 healthy controls (HCs). A noteworthy lncRNA, RP11-438N5.3, the function of which was previously unknown, was further explored on the aspect of the correlation of its expression level with clinicopathological factors. Results The results revealed that plasma level of RP11-438N5.3 was significantly lower in NSCLCs than that in HCs (p

Accurate fault location is crucial for finding and clearing faults in distribution networks. It can help to reduce the loss of power failure and ensure safe and stable operation. Without efficient observation points and the lack of phase angle information, traditional fault location methods of distribution networks usually have large errors. As the application of $\mu $ PMUs in the distribution network becomes more and more common, voltage and current waveforms, as well as phase angle can be recorded and provide more information for accurate fault location. In this paper, an intelligent location method is proposed to pinpoint the fault location based on the information of $\mu $ PMUs which are properly allocated. The fault section is firstly determined by comparing the zero-sequence current waveforms on both sides of the fault section. Then, a Stack Auto-Encoder (SAE) is modeled to provide an end-to-end solution to pinpoint fault point with the voltage and current phasors. Finally, the performance of the proposed method is tested by a simulated distribution network on the platform of PSCAD. The results show that the proposed method is effective in locating faults and can withstand the effects of transition resistance, fault type, and noise. Compared to another popular method, the proposed method shows better location accuracy.

For overhead long-distance high voltage direct current (HVDC) transmission lines, transients are produced due to complicated field conditions and lightning activities. To ensure reliable operation of protection devices, accurate recognition of faults and disturbances is quite critical. The most popular recognition methods include threshold-based ones which require the proper setting of the threshold value, and classifier-based ones that need suitable feature extractions. These methods depend heavily on the experience of engineers or experts and are ineffective in dealing with the variation of system parameters. In this paper, a transient recognition method based on stack auto-encoder (SAE) is proposed to characterize different transients and to avoid human interferences. A symmetrical ±500kv HVDC system is modeled to illustrate the performance of the proposed method. The effect of some factors, such as noises and conductors, are discussed and compared. The simulation results demonstrate that the proposed SAE-based recognition has excellent potential in transient recognition of practical HVDC systems.

Approximately 338,000 patients are diagnosed with kidney cancer worldwide each year, and renal cell carcinoma (RCC), which is derived from renal epithelium, accounts for more than ninety percent of the malignancy. Next generation RNA sequencing has enabled the identification of novel long noncoding RNAs (lncRNAs) in the past 10 years. Recent studies have provided extensive evidence that lncRNAs bind to chromatin modification proteins, transcription factors, RNA-binding proteins and microRNAs, and thereby modulate gene expression through regulating chromatin status, gene transcription, pre-mRNA splicing, mRNA decay and stability, protein translation and stability. In vitro and in vivo studies have demonstrated that over-expression of oncogenic lncRNAs and silencing of tumor suppressive lncRNAs are a common feature of human RCC, and that aberrant lncRNA expression is a marker for poor patient prognosis, and is essential for the initiation and progression of RCC. Because lncRNAs, compared with mRNAs, are expressed in a tissue-specific manner, aberrantly expressed lncRNAs can be better targeted for the treatment of RCC through screening small molecule compounds which block the interaction between lncRNAs and their binding proteins or microRNAs.

Recent technological developments in modular multilevel converter-based high-voltage direct current (MMC-HVDC) transmission systems have shown significant advantages over the traditional HVDC and two-level voltage source converter (VSC) transmission systems. However, there are a lack of studies on the protection methods for MMC-HVDC overhead lines where the protection method should be able to provide a fast and accurate response and be able to identify lightning strikes. In this paper, a wavelet entropy-based protection method is proposed. Due to the capability of revealing time–frequency distribution features, the proposed protection method combines wavelet and entropy to identify the time–frequency characteristics of different faults. Simulation results show that the proposed method can accurately and quickly determine the types of faults or disturbances with appropriate noise tolerance. In addition, the impact of the ground resistor and fault distance on the performance of the proposed method is studied.

Flexible high-voltage DC (HVDC) transmission system composed of half-bridge modular multilevel converters (MMCs) becomes more and more popular in China. As the most serious fault in MMC-HVDCs, short-circuit fault on transmission lines should be discussed carefully to improve the setting and performance of fault current controls and protections. Generally, the post-fault equivalent of short-circuit fault of half-bridge MMC is a RLC discharging circuit. The effect due to AC system is ignored. But the AC system continues charging capacitors before IGBT blocks. In this paper, to reduce the errors of fault current calculation, the AC charging of capacitors is considered by replacing the capacitance of each arm with varying capacitances. Simulations have been done to verify the calculation results. The comparisons show that the proposed method could be more accurate than the RLC equivalent method.

Hybrid DC transmission system becomes more and more popular in China because of its unique advantages. Compared with the boundary conditions of traditional highvoltage DC (HVDC) transmission systems, the boundary conditions of multi-terminal hybrid DC transmission systems have been changed. The coupling of the fault characteristics of different converters leads to differences in fault response. As the primary protection of traditional HVDC transmission lines, the adaptability of traveling wave protection in multi-terminal hybrid DC transmission lines is worth studying. In this paper, the fault characteristics and traveling wave characteristics of Kunliulong (KLL) multi-terminal hybrid DC transmission system are analyzed, and the adaptability of traveling wave protection is studied. Simulations have been done to verify the conclusion of adaptability. Also, the protection configuration schemes of DC lines are proposed.

Hybrid multi-terminal high-voltage direct current (HVDC) systems have become the most competitive and promising candidate for HVDC system. With the development, a new topology is proposed, whose receiving terminal involves line-commutated converters (LCCs) and modular multi-level converters (MMCs). The analysis of fault characteristics is lacking in this new hybrid multi-terminal HVDC system with complex topology and control strategies. In this paper, a typical topology simulation model of hybrid multi-terminal HVDC transmission system is built in PSCAD/EMTDC. The fault characteristics of hybrid multi-terminal HVDC system are analyzed, which is the basis for the subsequent protection theory research and practical application of engineering.

Compared with the two-terminal distribution system, the multi-terminal system has the characteristics of high flexibility and reliability. However, the fault analysis and protection are more complex. This paper analyzes the generation mechanism of short-circuit current of half-bridge converter, calculates the fault current of three-terminal ring network, and proposes a parameter matching method of DC circuit breaker and current limiting reactor which lays a foundation for the protection of the DC line. A three-terminal DC loop network is built in MATLAB to verify the correction of the parameter calculation method by simulation. The DC circuit breaker cooperated with the current limiter can isolate the fault within the breaking capacity, and the system voltage can recover rapidly after the fault is isolated.

DC circuit breaker is an effective way to isolate faults on the DC line. However, it cannot always meet the system requirements limited by the manufacture ability. DC current limiting reactor can reduce the fault current to within interruption capability of the DC circuit breakers (DCCB). Therefore, the parameter matching of DC current limiter and DC circuit breaker is of great significance to the reliability and stability of the system. However, there are no uniform standards for the parameter selection of DC current limiters at present. This paper analyzes the pole-to-pole fault and calculates the fault currents in a three-terminal radiation network, which provides a basis for the protection. And the parameter value calculation is based on the typical case of medium voltage. A Three-ended DC distributed system is built in MATLAB to verify the correctness of the design method by simulation.

Hybrid dc circuit breaker (HCB) is an effective device for interrupting dc fault currents in dc grids. Conventional two-port HCB requires too many insulated gate bipolar transistors (IGBTs) in series in its main breaker, resulting in considerable costs. Recently proposed multiport hybrid dc circuit breakers (multiport HCBs, and the number of ports is greater than or equal to 2) interrupt fault currents on multiple lines using only one shared main breaker, significantly reducing the implementation costs but losing some fault handling capabilities. To overcome these obstacles, we propose a novel high-performance economical multiport hybrid dc circuit breaker (MP-HCB) in this article. The topology and its control method are proposed. Due to the designed ring-connection structure, the proposed MP-HCB can avoid dc bus fault, and thus is more reliable. The electrical stresses of the breaker are theoretically analyzed, and the parameters are determined to make the MP-HCB capable of multiple-line faults. Compared with the typical two-port HCB and the existing multiport HCBs, the proposed MP-HCB can achieve full fault current interruption capability with lower costs. To protect a dc node connecting with three lines, the cost of the semiconductors of the proposed MP-HCB is only 1/3 of the typical two-port HCB and 1/2 of the existing multiport HCB. Finally, the performances of the proposed MP-HCB are verified via a four-terminal HVdc system in power systems computer aided design/ electromagnetic transients including DC (PSCAD/EMTDC).

The line-commutated converter-voltage source converter (LCC-VSC) three-terminal DC transmission system is one of the effective means for large-scale new energy transmission and consumption, and a fast and reliable protection scheme is the key to its reliable operation. However, the LCC-VSC DC system has characteristics such as LCC converter and VSC converter control strategies, fault response, and uneven boundary elements, which makes it difficult to directly apply the existing protection principles. To the above problems, this paper first proposed a single-ended protection principle based on line attenuation characteristics. The protection principle uses the ratio of the high and low-frequency signals of the line mode voltage to express the line attenuation characteristics and uses this ratio to identify internal and external faults. A model of the LCC-VSC three-terminal transmission system is established to verify the feasibility and effectiveness of the proposed protection scheme. The simulation results show that the proposed protection principle can accurately identify internal faults and external faults and has a strong ability to withstand fault resistance and noise interference.

Voltage source converters (VSCs) are highly vulnerable to DC fault current. Protection methods which can quickly locate and isolate DC faults are necessities in VSC-based multi-terminal DC (VSC-MTDC) systems for its safe and reliable operation. In this paper, a fast and collaborative DC fault location and isolation strategy are proposed. In this strategy, hybrid DC circuit breakers (HDCCBs) are used as the main protection device. The operation control of HDCCB is redesigned and cooperates with fault location results to achieve fast fault isolation. For the fault location method, a fast d i /d t criterion is used for fault pretreatment, the transient-voltage energy difference criterion is used to make sure its selectivity. The overall protection strategy is demonstrated in a four-terminal VSC-MTDC system using PSCAD/EMTDC platform. The performances of the typical DC circuit breaker-based strategy and the proposed strategy were compared. Numerous simulation results under various conditions proved its flexibility and validity.

This paper presents an end-to-end approach for locating faults on high-voltage dc (HVDC) transmission lines. Different from traditional methods which rely on communications between different measuring units or feature extraction of post fault transients, the proposed algorithm takes the raw data of locally detected traveling current surges as the only-input and outputs the fault locations directly. Especially, the stacked auto-encoder (SAE) is utilized to model the relationship between fault currents and fault locations. The SAE-based method is performed in time domain and tested with a simulated HVDC transmission line modeled in PSCAD/EMTDC. The simulation results show that this method is effective in locating faulted points and robust against attenuation, overlapping of traveling surges, and various ground resistances.

Accurate fault location of distribution network enables the fault to be quickly found and eliminated. It saves the manpower and material resources of the line inspection, reduces the losses caused by power outages, and ensures the safe and stable operation of the system. The traditional fault location method in distribution network uses the amplitude of voltage and current to calculate the fault distance without using the phase angle information. The distribution network operates in a variety of ways with fewer observation points. The actual line parameters of the system are inconsistent with the simulation parameters. At the same time, there is the access of distributed generation. All these make it is difficult to locate faults accurately in traditional distribution networks. With the application of the Micro Synchronous Phasor Measurement Unit (μPMU), phase angle information can also be used for fault location. Based on Stack Auto-encoder (SAE), in this paper, the voltage and current amplitude, and phase angle of the double-ended μPMU are used to train the SAE to calculate the fault distance. Line parameters, ground resistance and fault type are changed during training. A simulation model is built in PSCAD. The results show that this method is effective in fault location and robust against the effects of ground resistance and fault type. The effect of fault location will be very poor if only the amplitude of voltage and current is used.

This paper proposed a maximum traveling-wave-based fault location method for multi-terminal HVDC systems. The traditional traveling wave method based first-arrival-time cannot deal with the blind zones in MTDCs when a part of transmission paths are much longer than the others. The propagating features of traveling waves are studied, and the maximum traveling wave is proved to directly propagate from fault point and can be used in fault locations. With the arriving time of maximum traveling waves, all paths in MTDC are assumed to be faulted and the true faulted line is selected. A four-terminal meshed HVDC system is modeled, and faults with various parameters are simulated. The results demonstrate that the proposed method is effective in locating faults and has better performance than the traditional first-arrival-time methods.

Background Lung cancer is one of the most common malignancies around the world. The lack of early diagnosis and effective treatment strategies contributes to the poor prognosis of patients with lung cancer. Recent studies have implied the role of long non-coding RNAs (lncRNAs) in oncogenesis. The purpose of our study was to identify specific lncRNAs which were correlated with non-small cell lung cancer (NSCLC) and their potential functions. Materials and Methods The global plasma lncRNA profiling was performed using LncPathTM Human Cancer Array, and 11 lncRNAs were then selected for quantitative reverse transcription PCR (qRT-PCR) validation in 138 plasma samples from 69 NSCLC patients and 69 healthy controls (HCs). A noteworthy lncRNA, RP11-438N5.3, the function of which was previously unknown, was further explored on the aspect of the correlation of its expression level with clinicopathological factors. Results The results revealed that plasma level of RP11-438N5.3 was significantly lower in NSCLCs than that in HCs (p, Video abstract Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use: https://youtu.be/cZTolLw-1og

A massive number of hybrid DC circuit breakers (HCBs) have to be installed to protect a voltage source converter based multi-terminal DC (MTDC) system, leading to quite high costs. To reduce the implementation cost employing HCB in DC systems, this paper presents an integrated multi-port hybrid DC circuit breaker (IMP-HCB), which consists of an integrated HCB (IHCB) and a diode bridge. The topology of the breaker is presented, and the operation principles are introduced and analyzed. Comparisons between the existing typical HCB scheme and the proposed IMP-HCB scheme are conducted, showing that the cost of the proposed IMP-HCB scheme is much lower. The effectiveness of the IMP-HCB is verified via a three-terminal MTDC model built in PSCAD/EMTDC, and the performances are also compared to the typical HCB.

Nowadays, flexible HVDC transmission develops towards a direction of multi-terminal or meshed grid. When analyzing the post-fault transient responses of mutli-terminal HVDC (MTDC), the coupling effect of multiple converters is more and more important. Due to the non-linear characteristics and different control sequences of each convertors, the contribution of fault current from each convertor station cannot be simply added, and the time sequence of different converters should be considered. Hence, the time sequences of each convertor station are discussed and studied in this paper. A time sequence diagram is peoposed to segmentize the post-fault procedure, and the transient currents are calculated segment by segment. A multi-terminal DC transmission system based on modular multi-level converter (MMC) is modeled in PSCAD/EMTDC and used to test the calculation results. The results show that the calculation error of fault current is within a reasonable range, which verifies the correctness of the theory.

This paper proposed an intelligent algorithm based approach for fault location in a high voltage direct current (HVDC) transmission system. To obtain post-fault signals, the point-to-point HVDC transmission lines, including overhead lines and cables, are modeled on PSCAD/EMTDC. The data set is split into two parts used for training and testing, separately. The proposed method uses stacked denoising autoencoder (SDAE), which takes the raw training data as the input of network and can directly obtain fault locations. SDAE with unsupervised learning is utilized to extract representative features automatically from raw data in pre-training. Then labeled data is applied to network for fine-tuning in a supervised manner. The testing data is used for the evaluation of the proposed method. The simulation results indicate that the SDAE based method performs well in fault location and has robustness against noises, ground resistances, and system parameters.

VSC-HVDC transmission promotes grid-connection with renewable energy and long-distance consumption, which makes power system become main AC/DC hybrid grid structure. Power flow calculation is of critical importance in power system research. With renewable energy integrated into grid, randomness, fluctuation, and intermittency of renewable energy bring challenges to planning of AC/DC hybrid grid. The traditional power flow calculation method does not consider these uncertainty factors in the power grid, while the probabilistic power flow considers them. So, the probabilistic power flow is more suitable for the actual operation state of grid. In this paper, traditional Monte Carlo Simulation (MCS) and Latin hypercube sampling based MCS (LHS) are applied to the AC/DC hybrid grid. Then, their applicability is compared and analyzed. Finally, an AC/DC hybrid system consisting of two IEEE RTS-96 systems, a 3-terminal DC network, and a 4-terminal DC network is used to verify the applicability of MCS and LHS in AC/DC hybrid grid.

In the previous studies, the phasor data are processed as the amplitudes and the phases separately since existing methods are in the field of real numbers. To take advantage of the correlations between amplitudes and phases of phasors, a phasor principal components analysis (PPCA) method in polar coordinates is proposed in this paper. In PPCA, the conventional principal components analysis (PCA) is improved and extended to the field of complex numbers to process the phasors in polar coordinates. The actual PMU data measured in a subsynchronous oscillation incident are used to verify the compression performance of PPCA which is also compared with PCA. The result demonstrates that PPCA can achieve better performance by making use of the correlations between amplitudes and phases of phasors.

Partial discharge (PD) is caused by the localized electrical field intensification in insulating materials. Early detection and accurate measurement of PD are very important for preventing premature failure of the insulating material. Detection of PDs in metal-clad apparatus through the Transient Earth Voltage (TEV) method is a promising approach in non-intrusive on-line tests. However, the electrical interference from background environment remains the major barrier to improving its measurement accuracy. In this paper, a wavelet-entropy-based PD de-noising method has been proposed. The unique features of PD are characterized by combining wavelet analysis that reveals the local features and entropy that measures the disorder. With such features, a feed-forward back-propagation Artificial Neural Network (ANN) is adopted to recognize the actual PDs from noisy background. Comparing with other methods such as the energy-based method and the similarity-comparing method, the proposed wavelet-entropy-based method is more effective in PD signal de-noising. NRF (Natl Research Foundation, S’pore) Published version

Large scale application of renewable energy in distribution network generates more challenges for traditional protection methods. Longitudinal differential protection is a common backup protection method of DC system. It adopts measurements at the both ends of the line, and has a good performance in most cases except faults with high grounding resistance. To improve the protection reliability of DC distribution networks, this paper proposes a current increment direction based differential protection method. First, the current characteristics of various DC faults are analyzed. Then, the protection method is descripted. Finally, a DC distribution network is modeled on the platform of MATLAB/Simulink to test the performance of proposed method. Simulation results show the proposed method can operate accurately and be immune to large variations of grounding resistances and disturbances.

Voltage source converters (VSCs) are highly vulnerable to DC fault current. Fast and reliable fault location and protection methods are necessities in VSC-based multiterminal DC (VSC-MTDC) systems for its safe and reliable operation. In this paper, a selective transient-voltage based fault protection method is proposed. The protection method first uses fast overcurrent criterion as the starting element. Then based on the boundary characteristic of the supplemental inductors, the transient-voltage difference between the internal fault and the external fault is used to locate the fault line. And the extraction of the transient-voltage is achieved by wavelet transform. The proposed method is based on local information, it can identify the fault line quickly without communication between protection units at different locations. The methods has no auxiliary directional criterion and additional fault pole selection criterion. Besides, this method can be realized with very low sample rates, and it is rather strong against various fault resistances. Corresponding simulations were carried out, verifying its feasibility and validity.