Preventing third zone maloperation during power system stressed conditions

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Kasimala Venkatanagaraju ◽  
Monalisa Biswal
Keyword(s):  
New England ◽  
Average Rate ◽  
Test System ◽  
Rate Of Change ◽  
Distance Relay ◽  
Power Cycle ◽  
Power Swing ◽  
Protective Relay ◽  
Three Phase ◽  
Nuisance Tripping

Abstract The back-up third zone unit of distance relay may issue nuisance tripping command during different system critical events like power swing, voltage stress/instability and load encroachment. Since, such events are system symmetry phenomenon, the protection unit will not always able to discern them from three phase (symmetrical) fault in the distance relay third-zone region. The conventional relay algorithm fails to make a proper decision and results in unwanted tripping. This may further lead to system blackout. To mitigate this problem, a new approach based on the average rate of change of current (ARCC) is proposed. The method will work in integration with the conventional distance relay impedance setting algorithm to provide better results. The main advantage of the method is that it considers only local end current information. Within one power cycle, an accurate decision can be taken by the protective relay. The proposed method is validated considering IEEE 39-bus New England test system and the Indian regional power grid model modeled using EMTDC/PSCAD software. The simulation results for various critical cases and comparative analysis with existing methods shows effectiveness of the proposed method.

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

2016 ◽  
Vol 17 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Ujjaval J. Patel ◽  
Nilesh G. Chothani ◽  
Praghnesh J. Bhatt
Keyword(s):  
Reactive Power ◽  
Synchronous Generator ◽  
Power Input ◽  
Parallel Line ◽  
Rate Of Change ◽  
Electrical Network ◽  
Distance Relay ◽  
Heavy Load ◽  
Power Swing ◽  
Distance Relaying

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.

An Enhanced Symmetrical Fault Detection during Power Swing/Angular Instability using Park’s Transformation

2016 ◽  
Vol 2 (1) ◽  
pp. 23 ◽  
Author(s):  
Jeevitha A ◽  
Devi S
Keyword(s):  
Fourier Transform ◽  
Power Systems ◽  
Operating Conditions ◽  
Electrical Machine ◽  
Distance Relay ◽  
Power Swing ◽  
Three Phase ◽  
Wide Range ◽  
Simulation Results ◽  
Line Switching

<p>Power systems are subjected to a wide range of small or large disturbances during operating conditions. Power system disturbances such as line switching, generator disconnection and sudden removal of faults causes oscillations in an electrical machine rotor angles that can result in severe power swings. Depending on the protection controls, the system may remain stable or unstable and it may result in loss of synchronism. In recent years, distance relay finds difficulty between symmetrical fault and power swing which causes undesired tripping of the transmission line is the foremost reason for blackout. This paper proposes a new method Park’s Transformation and Fast Fourier Transform which are used to discriminate between the three phase fault and power swing and also to protect the backup zone of distance relay. This method is verified for normal and abnormal conditions with different load angles and different fault locations in IEEE 6-bus system are simulated in MATLAB/ Simulink. The Simulation results show the capability to avoid unwanted tripping decision of relay quickly and precisely.</p>

Study of Transformer Switching Overvoltages during Power System Restoration Using Delta-Bar-Delta and Directed Random Search Algorithms

2012 ◽  
Vol 13 (3) ◽  
Author(s):  
Iman Sadeghkhani ◽  
Abbas Ketabi ◽  
Rene Feuillet
Keyword(s):  
Power System ◽  
New England ◽  
Early Stage ◽  
Random Search ◽  
Test System ◽  
Worst Case ◽  
Power System Restoration ◽  
Three Phase ◽  
Equivalent Circuit Parameters ◽  
System Restoration

Abstract In this paper an intelligent-based approach is introduced to evaluate harmonic overvoltages during three-phase transformer energization. In a power system that appears in an early stage of a black ‎start of a power system, an overvoltage could be caused by core ‎saturation on the energization of a three-phase transformer with residual flux. ‎Such an overvoltage might damage some equipment and delay ‎power system restoration. A new approach based on worst case determination is proposed to reduce time-domain simulations. Also, an artificial neural network (ANN) has been used to estimate the temporary overvoltages (TOVs) due to three-phase transformer ‎energization. ‎ Three learning algorithms, delta-bar-delta (DBD), extended delta-bar-delta (EDBD), and directed random search (DRS), were used to train the ANNs. ANN Training is performed based on equivalent circuit parameters of the network; thus trained ANN is applicable to every studied system. The ‎developed ANN is trained with the worst case of the switching condition and remanent flux, and ‎tested for typical cases. The simulated results for a partial of 39-bus New England test system, ‎show that the proposed technique can estimate the peak values and ‎durations of switching overvoltages with good accuracy and EDBD algorithm presents best performance.

A New Blocking Scheme for Distance Protection during Power Swings

2010 ◽  
Vol 11 (1) ◽  
Author(s):  
Ahmad Farid Abidin ◽  
Azah Mohamed ◽  
Hussain Shareef
Keyword(s):  
Fast Algorithm ◽  
Reactive Power ◽  
Test System ◽  
Software Test ◽  
Test Results ◽  
Distance Protection ◽  
Distance Relay ◽  
Additional Criterion ◽  
Power Swing ◽  
Power Swings

This paper presents a new and fast algorithm to prevent distance relay mal-operation during power swings. The algorithm blocks the relay tripping signals during power swing and unblocks the signals if a fault occurs during power swing. The proposed blocking scheme for distance protection incorporates an additional criterion into the conventional relay which is based on the derivative of the line reactive power as seen by the relay. This technique overcomes the shortcoming of conventional power swing detector (PSD) by removing the pre-defined R-X diagram. The conventional PSD has the difficulty in obtaining the timer setting at pre-defined R-X diagram due to varying cycle of power swings. To illustrate the effectiveness of the proposed algorithm, simulations were carried out on the IEEE 39 bus test system using the PSS/E software. Test results show the effectiveness of the proposed scheme in blocking the relay’s false trip signals during power swing.

Detection of symmetrical fault and discrimination from power swing using MOPSVC approach

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Kumarraja Andanapalli ◽  
Monalisa Biswal
Keyword(s):  
Power System ◽  
Positive Sequence ◽  
Distance Relay ◽  
Security Issues ◽  
Power Swing ◽  
Three Phase ◽  
Sequence Components ◽  
Zero Sequence ◽  
Simulation Task ◽  
Eastern Regional

Abstract Distance relay are designed with swing blocking/tripping logic to maintain reliable and secure operation of power system. To prevent this from happening, the relay is functioned with a power swing blocking (PSB) logic. However, ensuring proper detection to swing event requires to overcome from the dependable situation such as three-phase fault. The relay refuses to behave normally if both swing and three-phase fault occur simultaneously. Reliable setting is essential to generate trip/block command. Unsymmetrical faults are easily detected during the swing condition due to the presence of negative and zero sequence components, but such components are absent in the case of symmetrical/three-phase fault. As a result, symmetrical fault under blocking condition is unidentified many a times by the distance relay, arising security issues. To improve the relay operation during swing and symmetrical fault conditions, a MOPSVC (multiplication of positive sequence voltage and current) based index is developed in this work. The MOPSVC index helps to discern power swing from three-phase fault. To test the efficacy of the method, a 230 kV, 50 Hz two-area four machine system, and Indian Eastern Regional Grid (IERG) network are considered. Simulation task is conducted using EMTDC/PSCAD software. To investigate the performance of the proposed method, various swing phenomena, faults, CT saturation, switching transients, and the presence of noise cases are considered, and the results demonstrate the robustness of the proposed algorithm. Responses under stressed power system conditions are also investigated, and a report on comparisons with existing methods is provided. Simulated results confirm that the proposed algorithm can balance the dependability and security aspects of the protection logic.

scholarly journals Detection of fault during power swing in test system interconnected with DG

2019 ◽  
Vol 16 (2) ◽  
pp. 577
Author(s):  
Nor Zulaily Mohamad ◽  
Ahmad Farid Abidin ◽  
Ismail Musirin
Keyword(s):  
Distributed Generation ◽  
High Resistance ◽  
Input Voltage ◽  
Test System ◽  
Distance Relay ◽  
Detection Scheme ◽  
Power Swing ◽  
S Transform ◽  
Voltage Signal

<span>Distance relay is prone to mal-operate during power swing, thus most of modern distance relay design is equipped with power swing blocking scheme to block the operation during power swing and reset the blocking operation whenever a fault occurs during power swing. However, the detection of fault during power swing especially for high resistance fault possess a challenging task, therefore it may cause the unblocking function to vulnerable to operate. This paper presents the development of a detection scheme for detecting fault during power swing in test system interconnected with Distributed Generation (DG). In this study, the detection scheme is proposed based on S-Transform analysis on the distance relay input voltage signal. It is demonstrated that the proposed S-Transform detection based scheme can effectively detect various type of fault during power swing includes high resistance fault, as well as able to operate correctly even with the presence of DG in the test system.</span>

scholarly journals A New Passive Islanding Detection Solution Based on Accumulated Phase Angle Drift

2018 ◽  
Vol 8 (8) ◽  
pp. 1340 ◽  
Author(s):  
Jinlei Xing ◽  
Longhua Mu
Keyword(s):  
Phase Angle ◽  
Low Cost ◽  
Rate Of Change ◽  
Islanding Detection ◽  
Physical Systems ◽  
Power Cycle ◽  
Three Phase ◽  
Voltage Phase ◽  
System Frequency ◽  
Vector Shift

The existing passive methods for islanding detection are mainly based on the detection of voltage and frequency deviation after islanding, using protections such as voltage vector shift (VVS) and rate of change of frequency (ROCOF). Although there are reported issues with these passive methods such as inherent non-detection zones and nuisance trips, utilities prefer the passive methods due to the low cost and simplicity of deployment. In this paper, one composite passive islanding detection method is presented. It tracks the voltage phase angle, the system frequency, and ROCOF every power cycle. If three phase voltage vectors shift in the same direction and the rotated angle values are balanced, the calculation of the accumulated phase angle drift (PAD) will be initiated. This calculation continues until the ROCOF measurement is below the ROCOF setting threshold. If the accumulated phase angle drift reaches the set angle threshold, the condition for islanding is claimed. The performance of this composite method is verified under different scenarios based on Matlab Simscape multidomain physical systems and practical waveforms recorded from sites. Although there are still non-detection zones, this composite PAD solution has better sensitivity than existing VVS and ROCOF methods and is stable under external system faults.

scholarly journals Weight Feedback-Based Harmonic MDG-Ensemble Model for Prediction of Traffic Accident Severity

2021 ◽  
Vol 11 (11) ◽  
pp. 5072
Author(s):  
Byung-Kook Koo ◽  
Ji-Won Baek ◽  
Kyung-Yong Chung
Keyword(s):  
Traffic Accidents ◽  
Average Rate ◽  
Modern Society ◽  
Rate Of Change ◽  
Weighted Voting ◽  
Independent Variables ◽  
Dependent Variables ◽  
Accident Severity ◽  
Harmonic Average ◽  
Bagging Method

Traffic accidents are emerging as a serious social problem in modern society but if the severity of an accident is quickly grasped, countermeasures can be organized efficiently. To solve this problem, the method proposed in this paper derives the MDG (Mean Decrease Gini) coefficient between variables to assess the severity of traffic accidents. Single models are designed to use coefficient, independent variables to determine and predict accident severity. The generated single models are fused using a weighted-voting-based bagging method ensemble to consider various characteristics and avoid overfitting. The variables used for predicting accidents are classified as dependent or independent and the variables that affect the severity of traffic accidents are predicted using the characteristics of causal relationships. Independent variables are classified as categorical and numerical variables. For this reason, a problem arises when the variation among dependent variables is imbalanced. Therefore, a harmonic average is applied to the weights to maintain the variables’ balance and determine the average rate of change. Through this, it is possible to establish objective criteria for determining the severity of traffic accidents, thereby improving reliability.

scholarly journals A New Indicator of Transient Stability for Controlled Islanding of Power Systems: Critical Islanding Time

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2975 ◽  
Author(s):  
Zhenzhi Lin ◽  
Yuxuan Zhao ◽  
Shengyuan Liu ◽  
Fushuan Wen ◽  
Yi Ding ◽  
...  
Keyword(s):  
New York ◽  
Power Systems ◽  
New England ◽  
Transient Stability ◽  
Time Frame ◽  
Test System ◽  
Crucial Importance ◽  
Interconnected System ◽  
Controlled Islanding ◽  
Simulation Results

Transient stability after islanding is of crucial importance because a controlled islanding strategy is not feasible if transient stability cannot be maintained in the islands created. A new indicator of transient stability for controlled islanding strategies, defined as the critical islanding time (CIT), is presented for slow coherency-based controlled islanding strategies to determine whether all the islands created are transiently stable. Then, the stable islanding interval (SII) is also defined to determine the appropriate time frame for stable islanding. Simulations were conducted on the New England test system–New York interconnected system to demonstrate the characteristics of the critical islanding time and stable islanding interval. Simulation results showed that the answer for when to island could be easily reflected by the proposed CIT and SII indicators. These two indicators are beneficial to power dispatchers to keep the power systems transiently stable and prevent widespread blackouts.

Acetyl L-Carnitine Slows Decline in Younger Patients With Alzheimer's Disease: A Reanalysis of a Double-Blind, Placebo-Controlled Study Using the Trilinear Approach

1998 ◽  
Vol 10 (2) ◽  
pp. 193-203 ◽  
Author(s):  
John O. Brooks ◽  
Jerome A. Yesavage ◽  
Angelico Carta ◽  
Daniele Bravi
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Average Rate ◽  
The United States ◽  
Rate Of Change ◽  
Disease Assessment ◽  
Controlled Study ◽  
Double Blind ◽  
Parallel Group ◽  
Longitudinal Effects

Objectives: To assess the longitudinal effects of acetyl-L-carnitine (ALC) on patients diagnosed with Alzheimer's disease. Design: Longitudinal, double-blind, parallel-group, placebocontrolled. Setting: Twenty-four outpatient sites across the United States. Participants: A total of 334 subjects diagnosed with probable Alzheimer's disease by NINCDS-ADRDA criteria. These data were originally reported by Thal and colleagues (1996). Measurements: Cognitive subscale of the Alzheimer Disease Assessment Scale (ADAS) given every 3 months for 1 year. Results: The average rate of change was estimated using the trilinear approach, which allows for periods of both change and stability. Both the ALC group and the placebo group exhibited the same mean rate of change on the ADAS (0.68 points/month). However, a multiple regression analysis revealed a statistically significant Age × Drug interaction characterized by younger subjects benefiting more from ALC treatment than older subjects. Further analyses suggested that the optimal, though not statistically significant, cutpoint for ALC benefit was 61 years of age. Conclusions: ALC slows the progression of Alzheimer's disease in younger subjects, and the use of the trilinear approach to estimate the average rate of change may prove valuable in pharmacological trials.

Sign in / Sign up

Export Citation Format

Share Document