Swing Detection Research Articles

Power swing detection and blocking of the third zone of distance relays by the combined use of empirical‐mode decomposition and Hilbert transform

This study aimed to develop a new method for detecting power swings and faults that may occur during these swings based on the combined use of empirical-mode decomposition and Hilbert transform. Power swings including line disconnection, fault occurrence, large sudden changes in the demand load, and reclosing, can cause a distance relay to malfunction and sever healthy lines from the network. Therefore, power swings and their simultaneous faults can pose a major challenge to protect the power systems. The proposed method in this study was tested on the standard IEEE 39-bus network for different power swing and fault states. It was also implemented on a distance relay manufactured by Vebko-Amirkabir Co. The evaluations show that the proposed method completely outperforms the conventional industrial method and other available methods in the literature. Since the proper functioning of this method depends on the choice of a threshold value, the current study also provides a simple and practical way to determine this threshold.

Hero: Automated Detection System for Prescription Stimulant Overdose via AI-Based Emotion Inference, Metabolite Detection, and Biometric Measurement

Over the past year, approximately 10,000 Americans have died by psychostimulant overdose, and over 50% of these deaths were caused by prescription stimulant misuse. A comprehensive approach to detect a drug overdose in the environment where it occurs is imperative to reduce the number of prescription stimulant overdose-related deaths. Teenagers are at the highest risk for prescription stimulant overdose, so this study proposes a multi-factor overdose detection system named Hero which is designed to noninvasively operate within the context of a teen’s life. Hero monitors five factors that indicate stimulant abuse: extreme mood swings, presence of amphetamine metabolite in sweat excreted from the fingertip, heart rate, blood pressure, and respiration rate. An algorithm to detect extreme mood swings in a teen’s outgoing SMS messages was developed by collecting over 3.6 million tweets, creating groups of tweets for euphoria and melancholy using guidelines adapted from DSM-5 criteria, and training six Artificial Intelligence models. These models were used to create a dual-model-based extreme mood swing detection algorithm that was accurate 96% of the time. A biochemical strip, which consisted of a diagnostic measure that changes color when in contact with amphetamine metabolite and a control measure that changes color when the appropriate volume of sweat is excreted, was created. A gold nanoparticle-based diagnostic measure and pH-based control measure were evaluated individually and on the overall strip. The diagnostic measure had an accuracy of 90.62% while the control measure had 84.38% accuracy. Lastly, a vital sign measurement algorithm was built by applying photoplethysmography image processing techniques. A regression model with height, age, and gender features was created to convert heart rate to blood pressure, and the final algorithm had an accuracy of 97.86%. All five of these factors work together to create an accurate and easily integrable system to detect overdoses in real-time and prevent prescription stimulant abuse-related deaths.

A new power swing detection method based on chaos theory

The power swing blocking function is a very important element for distance relays to prevent unwanted tripping of transmission lines. In this paper, a new method is proposed for blocking of distance relay when a power swing occurs. In proposed method, chaos technique is used to detect the power swing and discrimination the faults occurring simultaneously with a power swing. The proposed algorithm detects the power swing using logistic map and blocks the relay. Also, the relay will be unblocked by the proposed algorithm when a permanent fault occurs simultaneously with the power swing. To evaluate the performance of the proposed algorithm, different types of power swings and simultaneous faults are simulated in DigSilent software. Then, the achieved data from the simulations are used in the Matlab environment to apply chaos theory for distinguishing between power swing and faults. The proposed method is also implemented on a real-time relay and has been tested by using a tester device. The results achieved by various case studies demonstrate the pertinence of the proposed method.

Online Detection of Power Swing Using Approximate Stability Boundaries

This paper presents a power swing detection algorithm in multi-machine power systems, which uses wide-area synchrophasor measurements and is based on Zubov's stability boundaries. Zubov's boundary method, an approximation of the famous Lyapunov function, is very common for numerical analyses of power system stability. This work extends the concept of Zubov's approximation boundaries to online protection applications. First, the proposed protection algorithm constructs a series of Zubov's stability boundaries on power angle-frequency (δ-ω) plane for generators based on real-time measurements from phasor measurement units/merging units. Then, it tracks the trajectory of each generator in the δ-ω plane after the disturbance to differentiate out-of-step (OOS) conditions from stable swings. The proposed approach is suitable for online applications, which is a significant improvement over the existing methods for swing detection since it does not require offline studies and network reduction. Effectiveness of the proposed method is shown using a single-machine infinite bus and New-England 10-machine 39-bus systems. The proposed method is also implemented in a hardware-in-the-loop setup with a customized IEC 61850-based OOS relay, and performance is compared with a commercially available relay.

Wavelet energy-based stable and unstable power swing detection scheme for distance relays

Distance relays are susceptible to maloperation during postfault power oscillations in the system. This unintended operation of relays may lead to power system blackout. It is due to their inability to distinguish a stable from an unstable power swing and to take a tripping decision appropriately. This research paper proposes a fast and wavelet energy-based method to detect stable and unstable power swings for distance relays. The proposed method computes the angular velocity of an equivalent machine developed from the measurements available at a bus. The energy in the low frequency band of the equivalent machine angular velocity will assist the tripping decisions of transmission line relays during power swings. Compared to the conventional method using blinders, the advantage of this method is that it requires less hardware and less time to know whether the resulting power oscillations after fault clearing are going to be stable or not. The performance of the proposed method has been evaluated on 5-bus system, WSCC 9-bus system, and IEEE 14-bus and 30-bus systems considering different test scenarios. The results show that using this method improves the performance of distance relays in detecting stable and unstable power swings.

Stance and Swing Detection Based on the Angular Velocity of Lower Limb Segments During Walking

Lower limb exoskeletons require the correct support magnitude and timing to achieve user assistance. This study evaluated whether the sign of the angular velocity of lower limb segments can be used to determine the timing of the stance and the swing phase during walking. We assumed that stance phase is characterized by a positive, swing phase by a negative angular velocity. Thus, the transitions can be used to also identify heel-strike and toe-off. Thirteen subjects without gait impairments walked on a treadmill at speeds between 0.5 and 2.1 m/s on level ground and inclinations between −10 and +10°. Kinematic and kinetic data was measured simultaneously from an optical motion capture system, force plates, and five inertial measurement units (IMUs). These recordings were used to compute the angular velocities of four lower limb segments: two biological (thigh, shank) and two virtual that were geometrical projections of the biological segments (virtual leg, virtual extended leg). We analyzed the reliability (two sign changes of the angular velocity per stride) and the accuracy (offset in timing between sign change and ground reaction force based timing) of the virtual and biological segments for detecting the gait phases stance and swing. The motion capture data revealed that virtual limb segments seem superior to the biological limb segments in the reliability of stance and swing detection. However, increased signal noise when using the IMUs required additional rule sets for reliable stance and swing detection. With IMUs, the biological shank segment had the least variability in accuracy. The IMU-based heel-strike events of the shank and both virtual segment were slightly early (3.3–4.8% of the gait cycle) compared to the ground reaction force-based timing. Toe-off event timing showed more variability (9.0% too early to 7.3% too late) between the segments and changed with walking speed. The results show that the detection of the heel-strike, and thus stance phase, based on IMU angular velocity is possible for different segments when additional rule sets are included. Further work is required to improve the timing accuracy for the toe-off detection (swing).

Transient Potential Power Based Supervisory Zone-1 Operation During Unstable Power Swing

Unstable power swing (UPS) may cause unwanted zone-1 tripping. This is caused due to presence of electrical center within the reach of zone-1 of distance relay. Fast detection of unstable swing can assist distance relay in taking reliable decision. This paper suggests a new coordinate system with transient potential power as the y -coordinate and angular difference of positive sequence voltage phasors across the transmission line ( ${{\boldsymbol{\delta }}_{{\boldsymbol{\text{SR}}}}}$ ) as the x -coordinate. We observed that this coordinate system can be useful to successfully differentiate an UPS from stable power swing (SPS) and three phase fault. The prediction is fast enough to prevent an unwanted zone-1 operation of distance relay. IEEE-39 bus New England test system is used to validate the proposed scheme. The suggested method showed improved and fast unstable swing detection accuracy under different pre-disturbance and fault conditions.

DC offset estimation‐based fault detection in transmission line during power swing using ensemble of decision tree

The nuisance tripping of distance relay during power swing has been identified as one of the major causes for power system blackouts. Avoiding the risk of maloperation of distance relay and hence improving resilience during power swing, demands the development of a scheme capable of generating blocking signal during power swing and detecting a fault occurring with power swing from the measurement of current signal. In this regard, a protection scheme based on the hybrid framework of an ensemble of the tree, least square, and Adaline algorithm to perform the task of fault detection/classification, zone identification, location estimation, and power swing detection is proposed. The proposed scheme is based on the online estimation of DC offset information along with the fundamental component of the current signal. The performance of the proposed scheme has been analysed for diverse power swing and fault scenarios for two-machine system and Western System Coordinating Council 9-bus system. The simulation results reflect the effectiveness of the developed scheme in terms of sensitivity and reliability. Furthermore, to authenticate the effectiveness of the proposed scheme for practical scenarios, implementation, and validation of the proposed scheme has been carried out in a real-time environment using the OPAL-RT digital simulator.

Synchrophasor‐based system integrity protection scheme for an ultra‐mega‐power project in India

System Integrity Protection Scheme (SIPS) aids the normal protection scheme in case of certain special contingencies like tripping of important corridors/flow gates etc. to mitigate the voltage or angular instability, load generation imbalance and finally large-scale cascading catastrophes. A recent blackout incident in an ultra-mega-power project (UMPP) in India has motivated the authors to ponder upon a SIPS as a solution. As part of designing the SIPS, an efficient solution is formulated using synchrophasors for a well-known issue nonetheless an issue which still disturbs the Indian power system network with blackouts – i.e. unintended distance relay operation in the event of power swing. Here, real-time voltage and current phasors and the angular separation between the buses connecting faulted line, acquired by phasor measurement unit is utilised to derive a differential power coefficient (DPC). This study proposes a modified logic scheme for blocking/de-blocking of distance relays i.e. change the existing scheme with ‘block all zones except Zone-1’ to ‘block all zones on power swing detection’. Rate of change of DPC is derived here which aids in differentiating stable and unstable power swings. A special protection scheme is finally formulated based on the modified logic.

Detection of power swing and fault occurring simultaneously with power swing using instantaneous frequency

Energy transmission lines play a more important role in power transferring from producer to consumers. Energy transmission lines should be protected from the fault and the faults should be cleared as soon as possible time. Distance relays due to their simplicity application are widely used for protection of power transmission lines. When a power swing occurs in the power system the distance relay may mal-operate during this phenomenon. In order to prevent this, the power swing blocking function is used in distance relays. In this paper, a new method based on the rate of change of the instantaneous frequency is proposed. This method has been tested practically in a standard two-area network and its applicability for detection of different types of faults is presented. One of the features of this method is low computing and simplicity in implementation, independent of network type, unnecessarily complicated setting, high impedance fault detection, and unstable power swing detection. Also, the proposed method is compared with the conventional industrial method and it has been shown that the proposed method has better performance.

Power Swing Detection in UPFC-Compensated Line by Phase Angle of Current

Power swing blocker (PSB) is a complementary part of distance relay protection, that detects power swing, in order to prevent unintended operation of a distance relay. Unified power flow controller (UPFC) is used in power system to control both active and reactive powers and its operation during power swing influences the performance of PSB. In this paper, two traditional methods for detecting power swing are analyzed in UPFC-compensated condition to show how UPFC influences the performance of these methods. The indices proposed for the above-mentioned methods are examined in compensated condition. The results show that these indices may no longer work in systems with UPFC. In addition, this paper proposes a new method for detecting power swing based on the phase angle of current at relay point and compares it with two other methods. The new method distinguishes power swing from a fault through the trend of the phase angle of current. Finally, intensive studies are performed and simulations demonstrate the merits of the proposed method.

A Novel Approach for Improvement of Power Swing Blocking and Deblocking Functions in Distance Relays

Power swing conditions in power systems make distance relays take the wrong breaker action in some cases. In this context, power swing blocking and power swing deblocking are two important functions in distance relays so as to distinguish power swing from a fault, which maintains stability of system and continuity of the power supply. In this paper, a sample estimation and error calculation method based on Taylor Series expansion is proposed for improving power swing detection performance of the relay. Performance of the method is compared with four conventional methods and a novel method in literature. Analyses are carried out in two systems: single machine-infinite bus system with parallel lines and 68-bus New England test—New York power system for fault, power swing, and fault during power swing scenarios. Simulations and performance analyses are carried out by using EMTDC/PSCAD and MATLAB, respectively. According to the results, when performances in correct operation, algorithm response times, clarity of outputs, and time passed for program execution on processor are considered, the proposed method has the best performance overall. It is found that by using the proposed method, distance relay performance in correct operation and speed for taking power swing blocking and deblocking actions are improved.

An Adaptive Neuromuscular Controller for Assistive Lower-Limb Exoskeletons: A Preliminary Study on Subjects with Spinal Cord Injury.

Versatility is important for a wearable exoskeleton controller to be responsive to both the user and the environment. These characteristics are especially important for subjects with spinal cord injury (SCI), where active recruitment of their own neuromuscular system could promote motor recovery. Here we demonstrate the capability of a novel, biologically-inspired neuromuscular controller (NMC) which uses dynamical models of lower limb muscles to assist the gait of SCI subjects. Advantages of this controller include robustness, modularity, and adaptability. The controller requires very few inputs (i.e., joint angles, stance, and swing detection), can be decomposed into relevant control modules (e.g., only knee or hip control), and can generate walking at different speeds and terrains in simulation. We performed a preliminary evaluation of this controller on a lower-limb knee and hip robotic gait trainer with seven subjects (N = 7, four with complete paraplegia, two incomplete, one healthy) to determine if the NMC could enable normal-like walking. During the experiment, SCI subjects walked with body weight support on a treadmill and could use the handrails. With controller assistance, subjects were able to walk at fast walking speeds for ambulatory SCI subjects—from 0.6 to 1.4 m/s. Measured joint angles and NMC-provided joint torques agreed reasonably well with kinematics and biological joint torques of a healthy subject in shod walking. Some differences were found between the torques, such as the lack of knee flexion near mid-stance, but joint angle trajectories did not seem greatly affected. The NMC also adjusted its torque output to provide more joint work at faster speeds and thus greater joint angles and step length. We also found that the optimal speed-step length curve observed in healthy humans emerged for most of the subjects, albeit with relatively longer step length at faster speeds. Therefore, with very few sensors and no predefined settings for multiple walking speeds or adjustments for subjects of differing anthropometry and walking ability, NMC enabled SCI subjects to walk at several speeds, including near healthy speeds, in a healthy-like manner. These preliminary results are promising for future implementation of neuromuscular controllers on wearable prototypes for real-world walking conditions.

Distance Relaying with Power Swing Detection based on Voltage and Reactive Power Sensitivity

Abstract Sudden changes in loading or configuration of an electrical network causes power swing which may result in an unwanted tripping of the distance relay. Hence, it becomes utmost necessary to rapidly and reliably discriminate between actual fault and power swing conditions in order to prevent instability in power network due to mal operation of distance relay. This paper proposes a novel method for the discrimination between fault and power swing based on rate of change of voltage and reactive power measured at relay location. The effectiveness of the proposed algorithm is evaluated by simulating series of power swing conditions in PSCAD/EMTDC® software for different disturbances such as change in mechanical power input to synchronous generator, tripping of parallel line due to fault and sudden application of heavy load. It is revealed that the distance relay gives successful tripping in case of different fault conditions and remains inoperative for power swing with the implementation of the proposed algorithm. Moreover, the proposed scheme has ability to distinguish the symmetrical and asymmetrical fault occurrence during power swing condition.

Power-Swing Detection Using Moving Window Averaging of Current Signals

Power-swing blocking (PSB) function is necessary for the distance relay to avoid unwanted tripping of the transmission line. A power swing detection technique is proposed in this paper using a moving window averaging technique. The moving average of modulated current signal during power swing varies periodically whereas on inception of a fault, it remains either in positive or negative half. Using this property, two indices are calculated based on sign and time criteria of the moving average in order to distinguish the power swing from the balanced fault. The method is tested for numerous swing and fault conditions of a two-area four machine and WSCC 9-bus systems and compared with conventional methods.

Monitoreo en Tiempo Real de Oscilaciones de Potencia en el Corredor Oriental Molino – Totoras – Santa Rosa – Pomasqui utilizando Mediciones Sincrofasoriales de las Subestaciones Pomasqui y Molino a Nivel de 230 kV

En este trabajo se investigan y aplican los algoritmos Power Swing Detection, PSD y Predictive Out of Step Tripping, OOST, los cuales basan su funcionamiento en mediciones sincrofasoriales para la detección de condiciones oscilatorias y pérdida de sincronismo. Los algoritmos son dirigidos al problema de estabilidad angular que presenta el Sistema Nacional Interconectado (S.N.I) con el Sistema Eléctrico Colombiano ante contingencias N-2 en ciertas zonas de la Red Troncal de 230 kV, lo cual puede desencadenar condiciones oscilatorias inestables o bien la pérdida de sincronismo, si estas condiciones no son detectadas a tiempo y no se realizan acciones de control.
 Para lo cual se llega a desarrollar una herramienta computacional basada en sincrofasores en donde se aplica los algoritmos PSD y OOST, para ello se debe determinar previamente sus parámetros de ajuste característicos, los mismos que dependen del sistema de potencia en donde se los implemente. Esta herramienta permite observar y monitorear en tiempo real el comportamiento dinámico de los generadores cercanos a las barras de donde se obtiene las mediciones sincrofasoriales, además permite detectar condiciones oscilatorias estables e inestables, llegándose a obtener una herramienta adicional para la toma de decisiones en caso de ser necesario.

A Novel Power Swing Detection Scheme Independent of the Rate of Change of Power System Parameters

During power swings, the distance protection may experience maloperation. Most recently, practical distance protection has used the rate of change of power system parameters. For example, the speed of the impedance trajectory movement through the blinder characteristics is generally used to distinguish between the fault and power swing. These methods experience maloperation in the external faults or in stable power swings. The proposed method solves the shortcomings via an approach that does not use the rate of change of power system parameters. In this paper, the circular locus of the admittance trajectory and its center behavior are investigated to detect power swing conditions based on a relay flowchart. The proposed method is able to detect power swings reliably before the impedance trajectory enters the distance protection zone. In addition, symmetrical and asymmetrical faults during power swings can be detected quickly to prevent power system instability in critical conditions. Simulation results show that the proposed method provided superior performance in comparison with other methods, especially for maloperation. In addition, unlike most power swing detection schemes, the proposed method is not affected by the selected power swing frequencies even for high-frequency swings (10 Hz).

Intelligent Power Swing Detection Scheme to Prevent False Relay Tripping Using S-Transform

Abstract Distance relay design is equipped with out-of-step tripping scheme to ensure correct distance relay operation during power swing. The out-of-step condition is a consequence result from unstable power swing. It requires proper detection of power swing to initiate a tripping signal followed by separation of unstable part from the entire power system. The distinguishing process of unstable swing from stable swing poses a challenging task. This paper presents an intelligent approach to detect power swing based on S-Transform signal processing tool. The proposed scheme is based on the use of S-Transform feature of active power at the distance relay measurement point. It is demonstrated that the proposed scheme is able to detect and discriminate the unstable swing from stable swing occurring in the system. To ascertain validity of the proposed scheme, simulations were carried out with the IEEE 39 bus system and its performance has been compared with the wavelet transform–based power swing detection scheme.

Impact of UPFC on Power Swing Characteristic and Distance Relay Behavior

This paper analyzes the distance relay performance during power swing conditions for an uncompensated and compensated transmission line with a unified power-flow controller (UPFC). UPFC can control voltage and power flow of the transmission line independently; hence, it has an impact on the apparent impedance seen by the distance relay. To analyze the case, the apparent impedance seen by the distance relay during a power swing is extracted, and the results are synopsized graphically. The impact of UPFC on different transmission-line parameters from an impedance point of view is investigated. Moreover, the impact of different operation modes of UPFC and their reference values on the apparent impedance seen by concentric <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$mho$</tex></formula> circles as a power swing detection method are also evaluated by detailed simulations.

Blackout Prevention by Power Swing Detection and Out-of-Step Protection

Power swing evoked by sudden changes like faults or switching operations will become more and more important for protective relaying, due to the growing load flow in electrical power networks. Unwanted trips of the distance protection function must be avoided to prevent cascading effects and blackouts in the network. Selective out-of-step-tripping is required to stop unstable power swing and to prevent damage to affected generators. Therefore a reliable method for detection of power swing is presented, which requires no settings for operation. Power swing can be detected from 0.1 Hz up to 10 Hz swing frequency, also during open pole condition and during asymmetrical operation. A blocking logic prevents unselective trips by the distance protection. However, faults that occur during a power swing must be detected and cleared with a high degree of selectivity and dependability. For unstable power swing a flexible out of step tripping function will be proposed. The coordination of power swing detection, distance protection and out of step protection provides a reliable system protection.