Transmission Line Protection Research Articles

One-terminal traveling wave-based transmission line protection for LCC-HVDC systems

This paper proposes a one-terminal traveling wave (TW)-based transmission line protection for line commutated converter (LCC) of high-voltage direct current (HVDC) systems. The method requires the first and second wavefronts to reach the local bus and considers the boundary conditions of the system. A detailed mathematical analysis of the sampling frequency effects, as the basis for a number of innovations of practical interest, is presented here. Firstly, a definition of a minimum sampling frequency is formulated. This is crucial when dealing with the high sampling frequencies traditionally needed by TW-based methods. Secondly, mathematical expressions of protected, unprotected, and uncertainty zones on the transmission line are defined. Thanks to these calculations, the method is also capable of distinguishing faults at the line terminals from faults on the protected transmission line. Thirdly, the non-requirement for the TW propagation speed estimation is proven. Some TW-based protection elements require knowledge of the TW propagation speed, which is a source of errors. The proposed function presented good dependability and was able to operate below 15 ms for a transmission line of 2900 km in length.

Two-terminal traveling-wave-based non-homogeneous transmission-line protection

This paper presents a two-terminal traveling-wave-based protection algorithm applied to non-homogeneous transmission lines comprising any number of sections with different topologies and considering the effect of the sampling rate. Existing two-terminal traveling wave protection functions cannot protect the line under close-in faults and present limitations in non-homogeneous transmission lines. However, the effects of the sampling rate, considered in the proposed method, result in well-defined protection and unprotected zones, essential for protection security and coordination to deal with the issue of close-in faults in non-homogeneous transmission lines. Furthermore, the algorithm can accurately detect the faulted section, allowing its use in advanced protection functions such as adaptive automatic auto-reclosing and high-speed protection schemes. A protection device was modeled considering a sampling frequency equal to 1 MHz, including functions to detect traveling waves via wavelet transform, and the proposed protection algorithm to discriminate line internal from external faults, and to select the faulted section. The algorithm was evaluated using a large number of ATP fault simulations. The results show that the algorithm is robust and reliable for protection devices installed in non-homogeneous lines.

An algorithm for distance protection based on the change of the voltage phase angle

Conventional distance protection methods usually require additional filtering of the input signals to remove the influence of the DC component and the distortion of sinusoidal signals. The paper shows an algorithm that does not require additional filtering of the input signals. The proposed algorithm uses measured voltages at the beginning of the line and auxiliary voltages as input signals. The auxiliary voltages were calculated from measured currents and voltages at the beginning of the line and known line parameters. The algorithm compares the instantaneous values of the measured and calculated auxiliary voltages and detects a fault on the line based on the change in the phase angle of the voltage. Testing of the presented algorithm was performed with signals obtained from computer simulations of line faults and recordings of faults from protection devices from the real network. The obtained results confirmed that the algorithm represents fast and sensitive protection of transmission lines.

Transmission Line Protection Using Decaying DC Information in Fault Current

Today use of fast and reliable transmission line protection is of importance. This paper presents two protection techniques for transmission lines using information obtained from the decaying DC component of fault current and the pre-fault voltage signal. The fault direction is obtained using the polarities of pre-fault voltage and decaying DC of fault current. Internal faults in the transmission lines are detected with exchange of information on the decaying DC currents at both ends. The protection decisions are derived within a quarter cycle with a signal sampling rate of 4 kHz. Upon testing on a 400 kV simulated transmission system for different fault types, resistances, inception angles, and field data from a 400 kV line, the proposed techniques are found to be accurate.

Modelling and Experimental Investigation on the Differential Protection of Transmission Line

Due to the significant impact of the fault on power systems and the failure of protection devices, power system operators and researchers have given reliability a great deal of consideration. The modern IEC 61850 standard is used recently to improve communication systems in digital substations and allow signals to be shared between the devices. Differential protection is used to protect the transmission lines, cables, and transformers, as it detects the faults by comparison of the currents flowing into and out of the protected devices. In this research, MATLAB/Simulink has been utilized to simulate the differential protection by using two current transformers (CTs) and to analyze the current waveforms of CTs. A model of the transmission line has been implemented in Taylor’s University Lab to validate the simulation results and measure the differential current, which equals the current summation of two CTs. The outcomes of the research show that the phase shift in the secondary side of CTs between two terminal points is zero and the value of differential current is zero under normal operating situations. However, the differential current has increased in each of the following cases: one CT is connected to the system with the wrong polarity or under an internal fault.

Study on IEEE 2800-2022 standard benefits for transmission line protection in the presence of inverter-based resources

Study on IEEE 2800-2022 standard benefits for transmission line protection in the presence of inverter-based resources

Power differential protection for half-wavelength transmission lines—Software in the loop analysis

Half-wavelength transmission line protection is a challenge that hinders the implementation of this technology. However, this line is considered an interesting alternative to transmit bulk power blocks over very long distances and to connect wind and photovoltaic generation to an electrical power system. This study introduces a method to protect a half-wavelength transmission line. The proposed complex plane-based protection algorithm uses a differential complex power in the sequence domain to detect faults along the entire line. The embedded spark-gap mitigation device is properly considered because it is a necessary apparatus to remove severe resonant fault conditions. A time-domain analysis shows that the proposed algorithm achieves robust performance for both internal and external faults.

Amplitude Based Pilot Protection for Transmission Line

Abstract: Distance protection and differential protection schemes are the two primary types of protection schemes employed in gearbox line protection today. However, industrial practice has shown that commonly used gap prevention techniques are limited in tripping speed and selectivity. The timing of the samples in each of the two relays located at the gearbox line terminals also affects the differential protection mechanism. On the other hand, pilot safety schemes using only the communication link to exchange local decision-making about fault conditions are not affected. These method include protection of Extra High Voltage (EHV) and Ultra High Voltage (UHV) transmission lines. Synchronization of time. The problem of creating a fast and accurate fault detection system for the safety of EHV/UHV transmission lines, which is crucial in present power systems, is the subject of this master's thesis. The protection method described in this thesis is the foundation for the detection and analysis of waves travelling wave along transmission at fault initiation. This method compares the arrival of the first traveling waves at both ends of the protected line with respect to direction. This will establish whether the fault is located in the safe zone or not. Based on high voltage transmission network safety requirements a suitable phase sequence algorithm is developed to control single phase tripping. Finally, through simulations conducted in the MATLAB environment, practical design concerns for incorporating the newly proposed protection algorithm into a numerical relay unit are investigated.

A novel voltage projection component-based protection scheme for hybrid multi-terminal HVDC transmission lines

Combining the technical advantages of line commutated converter (LCC) and modular multilevel converter (MMC), hybrid multi-terminal HVDC (Hybrid-MTDC) system provides larger capacity, more economical and flexible transmission mode, which has become an important development trend of dc technology in the future. However, high fault resistance, complex topology and large transmission network pose great challenges to the protection of Hybrid-MTDC transmission lines. In this paper, the variation trajectories of internal and external fault voltage vectors with fault resistance are elaborated, and a projection axis through the origin is constructed on the vertical direction of the external metallic fault voltage vector. Combining the voltage amplitude and phase characteristics, the projection component amplifies the characteristic difference between internal and external high-resistance faults. On this basis, a voltage projection component-based protection scheme for Hybrid-MTDC transmission lines is proposed, which can sensitively and reliably identify the line faults under high fault resistance. Finally, the proposed method is thoroughly validated in the PSCAD/EMTDC simulation model of Kun-Liu-Long hybrid three-terminal HVDC system, and the results demonstrate that the proposed protection scheme is practicable, highly sensitive and reliable.

An intelligent fault detection and classification technique based on variational mode decomposition-CNN for transmission lines installed with UPFC and wind farm

The output voltage and current signals of grid-connected doubly-fed induction generator (DFIG)-based wind turbine generators (WTGs) are significantly modulated during grid disturbances. Consequently, the performance of conventionally used distance relaying-based transmission line (TL) protection schemes are affected. The problem becomes further complicated when the interconnected TLs are compensated with unified power flow controller (UPFC). In this paper, an intelligent relaying scheme is proposed for efficient detection and classification of faults in such crucial TLs. In the proposed method, the suitable features are extracted from the locally measured current signals using variational mode decomposition (VMD). The main advantage of VMD is that it can extract the different frequency components of a faulted current signal adaptively with fast convergence. The extracted gray-scale images through VMD are utilized further by the deep convolution neural network (CNN) classifier for effective classification of faults. The efficacy of the proposed relaying algorithm is evaluated on 12000 fault and 120 non-fault cases generated on a system comprising of DFIG-wind farm and UPFC compensation using MATLAB/Simulink® and real time digital simulation platform (OP4510). The fast fault detection time (¡10 ms), high accuracies in the fault detection and classification (100% and 99.86%) justify the merits of the proposed relaying scheme.

A novel pilot differential protection for HVDC transmission line based on the differential voltage

The HVDC transmission system has played an important role in modern power system. In traditional HVDC transmission line protection, the differential protection is invulnerable to high fault resistance, but its time delay is too long due to the distributed capacitance current. In order to solve this problem, a novel pilot differential protection is proposed in this paper. The compensating voltage on the setting point on the line can be calculated by using the voltage and current at two terminals of the line, separately. The difference value of the compensating voltages calculated by the voltage and current at rectifier side terminal and the inverter side terminal are defined as the differential voltage in this paper. When external fault occurs, the compensating voltage on the setting point calculated by the rectifier side terminal and inverter side terminal should be almost the same, so the differential voltage should be relatively small. However, when internal fault occurs, the compensating voltage on the setting point calculated by the two terminals are different, so the differential voltage should be relatively large. The analysis proves that the differential voltage can be used to identify the fault. A ±800 kV UHVDC system is modeled for simulation in PSCAD/EMTDC, and the correctness and effectiveness of the proposed protection method is verified.

Transmission line fault analysis using actuating relays and Atmega 328P controller

<span lang="EN-US">Since transmission lines account for 80–86% of power system problems, protecting transmission lines is a critical concern. This research proposes a method to identify and categorize various short circuit defects on transmission lines. Various operational and fault circumstances on the transmission of high voltage lines, including L-L fault, single phase to earth fault, and double line fault, double line Three fault scenarios triple line fault, triple line to ground fault, and triple line are simulated using MATLAB software. These flaws damage the linked devices to the power grid. The main motto of this work is to analyze various kinds of faults and also to detect the type of the fault in transmission line. In order to simulate and evaluate the various faults, a 100 km transmission line model was created. A sim power system block library had a fault block, and the harmonic content of the various faults was studied using the FFT tool, the effect of faults was observed. Based on the analysis, a hardware model is designed to identify the faults in transmission line using actuating relays and Atmega 328P microcontroller and display the fault type and parameters like fault impedance, and distance at which fault occurred.</span>

Experimental Study on the Transient Electric Shock Characteristics Between Metal Sheds and the Human Body Near Ultrahigh Voltage Alternating Current Transmission Lines

With the development of ultrahigh voltage (UHV) transmission lines in China, line corridors are becoming increasingly limited, and the lines pass closer to inhabited areas and the occurrence probability of induced electric shocks are increased. The research on transient electric shock and human sensory is essential due to the displeasure and complaints of people on electric shock. In this article, a real-size metal shed was established near a 1000-kV UHV alternating current (ac) transmission line, and the induced voltage and transient current characteristics were studied when the human body was in contact with the shed. Then, the amplitude and pulsewidth of the transient electric shock current were investigated, and the associations between discharge energy and sensation were established. The research found that transient electric shock is the most serious when the grounded human body contacts the insulated shed, and the imparted electric shock energy reaches 25 mJ. When the body and the shed are grounded, there is no electric shock sensation. When the insulated human body is in contact with the insulated shed, the electric shock sensation is intermediate, and women's perceptions of pain are more intense. The results provide references to transient electric shock protection for power transmission lines.

An intelligent overcurrent relay to protect transmission lines based on artificial neural network

Power systems are susceptible to faults due to system failures or natural calamities. This could be caused by damage to power system components, resulting in an interruption of power delivery to clients. Overcurrent relays are important relays that protect distribution feeders, transmission lines, transformers, and other components. The intelligent relay can perform both primary and secondary functions. Line-to-ground (L-G) faults are the most common occurrence in long transmission lines, posing a serious threat to electrical equipment. This article presents improved fault classification for transmission line overcurrent protection and highlights the use of artificial neural network (ANN) techniques to protect transmission lines of 100 km (terco type). An ANN is used to classify the faults. A back propagation neural network (BPNN) is used in this case. The neural network has been trained to classify faults in transmission lines for overcurrent protection. Various fault conditions are considered. In the event of a fault condition, the output of a neural network will be a tripping signal. The MATLAB neural network tool and the Simulink package are used to model the suggested method.

Optimal Deployment in Moving Target Defense against Coordinated Cyber–Physical Attacks via Game Theory

This work proposes a method for the intelligent deployment of distributed flexible AC transmission system (D-FACTS) devices. In recent years, in the field of moving target defense (MTD) strategies to detect coordinated cyber–physical attacks (CCPAs), establishing how to deploy D-FACTS devices has become an important research point. Although some research results have been proposed, the obtained deployment solutions are unintelligent due to not carefully considering smart attackers’ behaviors. A method for achieving the intelligent deployment of D-FACTS devices is proposed in this paper. First, the basic concept of corrupting CCPAs is summarized; second, based on considering practical constraints and the basic concept, a protected transmission line set is confirmed; and third, a zero-sum game model is formulated, and a robust Nash equilibrium solution is computed. Due to the game’s characteristics, this solution reflects the smart attackers’ sense of action. Relying on the solution, those lines that are most likely to be tripped form a new protected transmission line set. Finally, a comprehensive algorithm using a metric proposed in previous studies is proposed for finding an intelligent solution for the deployment of D-FACTS devices. We validated our results through extensive simulations using IEEE 14-bus, 30-bus, and 118-bus power systems provided by MATPOWER and the real-world load profiles from New York State. Our work, in tracking the targets that attackers are most likely to attack, opens up new ideas for the intelligent deployment of D-FACTS devices.

Single-end traveling wave protection method in flexible DC transmission line based on dominant frequency attenuation characteristics

The conventional traveling wave protection (TWP) for flexible DC transmission lines suffer from low-sensitivity problem in far-end high-impedance faults. Also, they are lack of theoretical basis in threshold setting. In this paper, the initial traveling wave is analysed considering the frequency attenuation law and discrepancy between internal and external faults. Then, the frequency domain expressions of the initial traveling wave are analysed deeply. By enhancing the influence of high-frequency components in energy calculation reasonably, the initial traveling wave dominant frequency (ITWDF) is constructed, which can reflect the fault location and the attenuation characteristics of the boundary. The expressions of the ITWDF show that the ITWDF decreases with the increasing fault distance, and the ITWDF is significantly different between the internal faults and the external faults. On this basis, a single-ended TWP method based on the attenuation characteristics of the ITWDF is proposed. The method is immune to the fault impedance, and the expressions of the ITWDF provide a theoretical basis for protection threshold setting as well. The simulation results show that the proposed method can fast and correctly identify line faults, even with 1000 Ω fault impedance. The ITWDF can reflect the fault location effectively, and the threshold setting is simple. Moreover, the proposed method is high-adaptability in different network topologies.

A non-unit transmission line protection scheme for MMC-HVDC grids based on a novel distance criterion

Ultra-fast, selective, and reliable protection is significant for MMC-HVDC grids. The methods utilizing the characteristics of fault current limiting reactor (FCLR) are unsatisfactory to detect high resistance faults. In this paper, a novel distance criterion is proposed to form the non-unit protection scheme. The line-zero-mode fault equivalent circuit is built to analyze the characteristics of fault traveling waves at the inductive terminal considering the influence of MMC and the refraction and reflection at the fault point. A multi-resolution morphological gradient algorithm (MMGA) is employed to extract the geometric features of the fault traveling waves. The magnitude of the first modulus maxima of the line-mode fault voltage after MMGA constitutes the start-up criterion. The estimated velocity and the change direction of the line-mode components are adopted to identify if the fault happens in-region. The 4-terminal ±500 kV MMC-HVDC grid built in PSCAD/EMTDC demonstrates that the proposed scheme can accurately identify various faults. The sensitivity analysis shows that the proposed scheme is almost immune to the size of FCLR, the equivalent parameters of MMC, the noise environment, and the DCCB breaking process. The proposed scheme has low requirements for sampling frequency and can be utilized to identify the temporary fault.

Shunt faults detection and classification in electrical power transmission line systems based on artificial neural networks

PurposeThis study aims to focus on an adaptive method for fault detection and classification of fault types that trigger in three-phase transmission lines using artificial neural networks (ANNs). The proposed scheme can detect and classify several types of faults, including line-to-ground, line-to-line, double-line-to-ground, triple-line and triple-line-to-ground faults.Design/methodology/approachThe fundamental components of three-phase current and voltage were used as inputs in the ANNs. An analysis of the impact of variations in the fault resistance, fault type and fault inception time was conducted to evaluate the ANNs performance. The survey compares the performance of the multi-layer perceptron neural network (MLPNN) and Elman recurrent neural network trained with the backpropagation learning technique to improve each of the three phases of the fault detection and classification process. A detailed analysis validates the choice of the ANNs architecture based on the variation in the number of hidden neurons in each step.FindingsThe mean square error, root mean square error, mean absolute error and linear regression are measured to improve the efficiency of the ANN models for both fault detection and classification. The results indicate that the MLPNN can detect and classify faults with a satisfactory performance.Originality/valueThe smart adaptive scheme is fast and accurate for fault detection and classification in a single circuit transmission line when faced with different conditions and can be useful for transmission line protection schemes.

Analysis of the Effect of Lightning Strikes on Travelling Wave Signal (TWS) in Determining Interference Points on 150 kV Transmission Lines (Glugur–Paya Geli Substation)

Transmission lines must be designed by considering several aspects such as reliability, economy, and safety. Therefore, the transmission line protection system must work sensitively, selectively, quickly and reliably in the event of a lightning strike. Travelling wave Signal can detect fault points when the transmission line is disrupted due to lightning strikes. This study aims to analyze the performance of the Traveling Wave Signal in determining the fault point due to lightning strikes at the Glugur–Paya Geli Substation. In this study, we will analyze various supporting data obtained from PT PLN (PERSERO) to determine the performance of the Traveling Wave Signal in determining the disturbance point. Travelling Wave Signal in determining the point of disturbance based on the actual distance in the field has a reading error not exceeding above 2%. From this study it was found that Traveling Wave Signals can be used in all substations in Indonesia as a comparison in determining the location of fault points.

Current- and Voltage-Actuated Transmission Line Protection Scheme Using a Hybrid Combination of Signal Processing Techniques

This paper presents a current- and voltage-driven protection scheme for transmission lines based on a hybrid mix of Stockwell transform (ST) and Hilbert transform (HT). Use of both current and voltage waveforms to detect and categorize faults, improves the reliability of this protection scheme and avoids false tripping. Current and voltage waveforms captured during a period of fault are analyzed using ST to compute a median intermediate fault index (MIFI), a maximum value intermediate fault index (MVFI), and a summation intermediate fault index (SIFI). Current and voltage signals are analyzed via applying HT to compute a Hilbert fault index (HFI). The proposed hybrid current and voltage fault index (HCVFI) is obtained from the MIFI, MVFI, SIFI, and HFI. A threshold magnitude for this hybrid current and voltage fault index (HCVFITH) is set to 500 to identify the faulty phase. The HCVFIT is selected after testing the method for various conditions of different fault locations, different fault impedances, different fault occurrence angles, and reverse flows of power. Fault classification is performed using the number of faulty phases and an index for ground detection (IGD). The ground involved in a fault is detected by comparison of peak IGD magnitude with a threshold for ground detection (THGD). THGD is considered equal to 1000 in this study. The study is carried out using a two-terminal transmission line modeled in MATLAB software. The performance of the proposed technique is better compared to a discrete wavelet transform (DWT)-based technique, a time–frequency approach, and an alienation method. Our algorithm effectively detected an AG fault, observed on a practical transmission line.