Power Swing Blocking Research Articles

Signal Envelope-Based Adaptive Power Swing Blocking

This research paper proposes detection of faults during power swings by using a peak envelope-based method to prevent incorrect distance relay operation. Distance relays should not operate during power swings except to remove a correctly detected fault event. In this study, distinction between faults and power swings is achieved by correctly observing fault occurrence based on dynamic thresholds generated by peak envelopes. The method utilizes a DC offset current in determining the fault inception and fifth harmonic voltage to assess the fault clearance. If the current surpasses the calculated threshold due to fault existence, the relay is allowed to operate. Re-blocking the relay after fault clearance is achieved in the case of a higher value of the voltage than the threshold value. Current and voltage data obtained from two different test systems simulated in PSCAD for various scenarios have been used in the proposed algorithm developed in MATLAB. In order to show the effectiveness of the proposed method, the results on the second test system have also been compared to the results of selected methods in the literature. It has been perceived that the developed method has a high accuracy and provides an appropriate time range for relay and breaker operation.

Fault Section Recognition within Duration of Power Swing Using Teager–Kaiser Energy Operator and Sequence Components

Relaying operation is not reliable during power swing due to the presence of additional lower-frequency components of electrical signals. Relay operation is prohibited during Power swing blocking (PSB) operation to restrict the malfunctioning of the distance relay. During such periods, fault section identification (FSI) schemes need to work for safeguarding the electrical power system from disturbances. Fault detection and fault direction estimation are part of FSI. This article proposes a protection algorithm within the period of power swing where a Teager–Kaiser energy operator (TKEO) of superimposed negative sequence admittance (SNSA) is utilized for fault detection and an integrated scheme for determining their direction. In this integrated direction estimation approach, the direction of fault is recognized by calculating the phases of negative sequence admittance (NSA) and positive sequence admittance (PSA). The proposed technique is verified and tested on a WSCC 9-bus, 400 kV, 50 Hz system for different balanced and unbalanced fault cases with different fault conditions. Even, in some scenarios like CT saturation and single pole tripping (SPT), the proposed approach performs accurately. The results are simulated using EMTDC/PSCAD software.

Renewable Energy Impact on Distance Relay Power Swing Blocking and Fault Discrimination: A Review

The annual increase of the global load demand has led to higher penetration of inverter-based renewable energy resources like wind farms and solar PV into the modern grid system. Distance relay may mal-operate by incorrectly estimating line impedance as fault during swing scenarios considering the infeed contributions impact from renewable sources. The negative impact of these integrated power electronics-based devices on the power swing blocking (PSB) and out-of-steps tripping (OST) functions of the distance relay characteristics has not been extensively discussed in previous studies. This study divulges a comprehensive review of the various PSB and OST schemes studies conducted to prevent relay mal-operation during power swing (PS) and symmetrical faults. Also, the large-scale renewable resources penetrations impact the PS characteristic and trip decision operation of the distance relay divulged. The mining of distance relay event records for hidden useful knowledge deployment for intelligent PSB and OST functions is the future research direction. Using the distance relay divulged knowledge will assist in reducing the failure rate level of PSB and OST function distance relaying schemes, hence improving the degree of reliability/dependability of the power system under different operating conditions.

Improving power swing detection in the presence of doubly-fed induction generator wind farms based on setting adaptation

This article proposes a new approach to improve the security of transmission line protection by correctly detecting power swing when large-scale doubly-fed induction generator wind farms (DFIGWF) exist in the proximity of the relay. In the presence of large-scale DFIGWFs, following large disturbances, power swing may probably cause the distance protection to malfunction. This issue can also lead to widespread transmission line outage and cause instability in the power system. Therefore, a new approach is proposed to solve the challenge by adapting the power swing blocking (PSB) function in the distance protection relays and utilizing the dominant power system oscillation modes. Thus, related calculations are performed in a central module remotely connected to intelligent electronic devices (IEDs) for distance protection and stabilized against power swing. The calculation to adjust the PSB setting of the IEDs in the central module is based on the oscillation modes of the power system and the rate of change of impedance, which is influenced by the penetration rate of the DFIGWFs. Simulation studies have been done on two test systems and the results reveal that the proposed scheme significantly improves the security of distance protection against power swing under different DFIGWF intrusion conditions.

Impact of inverter-based resources on transmission line relaying -part II: power swing protection

The power swing characteristic of transmission lines (TLs) can be affected by the large-scale integration of inverter-based resources (IBRs), resulting in the maloperation of the legacy power swing blocking (PSB) and out-of-step tripping (OST) functions. This paper presents a brief review of power swing phenomena and the impact on power swing protection functions. In this regard, the impact of IBR integration of type-III, and type-IV wind turbine generation (WTG) on legacy power swing protection functions has been scrutinized. To do so, the performance of impedance-based PSB and OST functions during the IBR integration has been investigated via comprehensive simulation studies. The results show that under a system contingency and high IBR penetration, depending on the IBR technology, the system experiences frequency oscillations and swinging impedance trajectories which are different from those from synchronous generators, such that the reliable operation of the legacy PSB and OST functions can be jeopardized. Moreover, during power swing phenomena, the simulation results have found that the security of distance protection cannot be guaranteed and the fault ride-through requirements cannot be maintained when a high share of IBRs have been integrated.

A new method for improving the fault detection performance of distance relays during power swings

System oscillations caused by circuit breaks, faults, etc. are called power swings, which have similar characteristics to symmetrical faults and often enter the action area of distance relays causing trips. As a transmission line that undertakes the transmission of electricity in the power system, unnecessary tripping can damage the reliability of the network, so it is crucial for distance relays to work with a reliable power swing blocking and unblocking function. This paper proposes a new method of constructing Archimedean spiral based on current signals, which calculates the instantaneous angular velocity using the spiral trajectory. The proposed method works at a fixed threshold, which is related only to the system operating frequency and swing frequency, and is tested numerically in IEEE 9 buses and four-machine two-area systems to simulate a variety of faults and power swing scenarios by varying different parameters, the results show that the fault detector improves the distance protection during power swings.

Reliable protection for static synchronous series compensated double-circuit transmission lines based on positive sequence active power calculations using PMUs

Static Synchronous Series Compensator (SSSC) allows dynamic control capabilities of transmitted power. Unfortunately, inserting SSSC in transmission lines (TLs) disturbs impedance-based distance relays as their directionality and reachability are affected by overreaching or underreaching. This paper proposes an approach for protecting double-circuit TLs compensated with SSSC. It relies on the centralized wide-area protection architecture to calculate a proposed driven index: the rate of change of positive sequence active power difference. Phasor measurement units (PMUs) at TL ends estimate voltage and current phasors to calculate the positive sequence active power at TL ends and send them to the system protection center that evaluates the index and gives the trip decision or not. Ensuring the sensitivity, dependability, and security of the approach is essential. So, the overall scheme integrates two other algorithms. One is based on the polarities of the incremental power at both ends to determine whether the fault is internal or external. The other evaluates the phase angle of the integrated impedance to deactivate the power swing-blocking function for fault detection. The scheme's effectiveness is validated comprehensively through extensive simulation tests for fault and system conditions. The results show that the proposed approach is fast, secure, selective, and reliable.

Analysis of Oscillations during Out-of-Step Condition in Power Systems

Power systems interconnected by weak tie lines can be subject to low-frequency oscillations because of disturbances which excites the low-frequency modes of the system; furthermore, these oscillations can be stable or unstable. The latter, if not treated, can cause severe oscillations that divide the network into smaller groups which oscillate against each other, leading to out-of-step (OOS) condition in the network. The detection of OOS condition is a challenge for power system operators in real time as it is difficult with conventional measuring instruments, to identify the instant at which the bus voltage angle between two areas connected by tie line falls out of synchronism. Conventionally, the detection of OOS condition has been carried out with impedance-based relays along with power swing blocking. With the advent of synchrophasor-based measurement units, it is now possible to measure the bus voltage angle in real time leading to direct detection of OOS condition in power system and intentional islanding. In this article, a systematic analytical study and EMT time-domain simulation study have been performed to simulate OOS condition in the power systems, and its detection is based on the voltage angle difference with wide-area measurement systems (WAMSs). The article has been carried out on a single machine infinite bus (SMIB) to monitor generator OOS, Kundur’s two-area system to detect interarea OOS, and the IEEE39 bus system to identify OOS condition and with a new algorithm. Time-domain simulation studies carried out with OPAL-RT real-time simulator in HYPERSIM environment corroborates with analytical results.

A Straightforward Power Swing Detection Algorithm Using Rate of Impedance Angle Change

Mal-operation of distance protection relays during power swing (PS) condition can endanger the power system stability. Therefore, it is crucial to distinguish between short-circuit faults and PS by a power swing blocking (PSB) function to prevent undesired tripping of distance relay. This paper develops a novel and straightforward PSB method based on the rate of impedance angle change (RIAC). Not only can the proposed approach fairly discriminate both symmetrical and asymmetrical faults from PS, but also it can appropriately preserve protection scheme security during PS under single-pole tripping (SPT) on a transmission line. Furthermore, there is no need to perform extensive dynamic stability studies for setting the PSB function parameters. Unlike the rate of impedance change approaches utilized two blinders, the developed approach only needs an inner blinder. Thus, it can be used for networks running near their operational limits. The proposed method is evaluated through a modified IEEE-PSRC benchmark system in PSCAD/EMTC environment. The obtained results verify superior performance of the proposed method to traditional impedance rate of change method under different scenarios.

Improved Deep Neural Network (IDNN) with SMO Algorithm for Enhancement of Third Zone Distance Relay under Power Swing Condition

A zone 3 distance relay is utilized to provide remote backup protection in the event that the primary protection fails. However, under stressful situations such as severe loads, voltage, and transient instability, the danger of malfunction in distance relay is relatively high since it collapses the system’s stability and reliability. During maloperation, the relay does not function properly to operate the transmission line. To overcome this problem, an advanced power swing blocking scheme has been developed. An improved DNN-based power swing blocking system is proposed to avoid the maloperation of the distance relay and improve the system’s reliability. The current and voltage signal of the system is sensed, and the sensed data is fed into the Improved Discrete Wavelet Transform (IMDWT). The IMDWT generates the coefficient value of the sensed data and further computes the standard deviation (SD) from the coefficient, which is used to detect the condition of a system, such as normal or stressed. The SD value is given to the most valuable algorithm for the improved Deep Neural Network (IDNN). In the proposed work, the improved DNN operates in two modes, the first mode is RDL-1 (normal condition), and the second mode is RDL-2 (power swing condition). The performance of the IDNN is enhanced by using the threshold-based blocking approach. Based on the threshold value, the proposed method detects an appropriate condition of the system. The proposed method is implemented in the Western System Coordinating Council (WSCC) IEEE 9 bus system, and the results are validated in MATLAB/Simulink software. The overall accuracy of the proposed method is 97%. The proposed method provides rapid operation and detects the power swing condition to trip the distance relay.

Distance Protection of Transmission Lines in Presence of Inverter-Based Resources: A New Earth Fault Detection Scheme During Asymmetrical Power Swings

Although it is commonly assumed that power swing is symmetrical and will have identical effects on all three-phase voltages and currents, there is another type of power swing, which is asymmetrical and mainly occurs during single-pole tripping (SPT), the impact of which on power systems integrated with the inverter-based resources (IBRs) has not been investigated so far. Since the likelihood of the occurrence of asymmetrical power swing is increasing in today's heavily loaded transmission lines, this article investigates the impact of IBR integration on the performance of distance protection during single-pole tripping. Furthermore, a new scheme is proposed to detect earth faults that occur during asymmetrical power swings to enhance the performance of power swing blocking functions. To do so, the superimposed component of the zero-sequence current during SPT is extracted. Then, the moving average window is used to calculate the average of both zero-sequence current and its superimposed component. Furthermore, to enhance the security of the proposed scheme, a new technique based on the phase angle shift between the three-phase currents is devised to detect the asymmetrical power swing conditions. This article shows that as the penetration level of IBRs increases, the standard reclosing dead-time needs to be revisited otherwise it can create an unstable power swing condition, even during SPT. Moreover, this article shows that the proposed earth fault detection scheme can efficiently detect all single-line-to-ground faults occurring during SPT.

Rate of Change of Active Power as a Power Swing Blocking Function of Distance Relays

Power swings may cause undesired trips of protection relays and, consequently, shutting down power utility equipment, leading to the outage of loads. This paper presents a procedure for detecting power swings based on the rate of change of active power. When a power swing occurs, the derivative of the active power can be modeled as a sinusoidal function and, therefore, it is possible to estimate the frequency oscillation. The proposal takes advantage to this theoretical concept to detect power swings on transmission systems. Simulation results show that the developed algorithm has good performance, including research scenarios against low and large power swings. The protection relay is unblocked upon the occurence of a short-circuit. The proposed technique is simple to implement and can be employed as a Power Swing Blocking (PSB) function to avoid misoperation of distance protection relays.

Enhancing distance relay performance using wide-area protection for detecting symmetrical/unsymmetrical faults during power swings

The distance protection in transmission networks is vulnerable to malfunction during a power swing. Distance relays have a power swing blocking (PSB) function that prevents the relay from operating during a power swing. However, during a power swing, the relay will be able to identify and clear any fault. This paper offers a scheme for detecting symmetrical/unsymmetrical faults through power swing by estimating the maximum rate of change of a (ΔI-ΔV) ellipse circumference. The ellipse circumference of each phase is constructed at each power frequency cycle to consistently tracking the distinction in the measured current and voltage differences between the line's two ends. The main feature of the suggested work compared to previous works is the ability to detect numerous high impedance faults (HIFs) during single mode (slow/fast) power swing or multi-mode power swing in addition to the opportunity to detect faults during asymmetrical power swing. The suggested scheme is tested in a two-area, four-machine power system and tested also in the standard three-machine, nine-bus system using ATP software. The results reveal that the improved protective scheme performs well in fault conditions with and without power swing, and they confirm the scheme's suitability for interconnected networks.

Setting and Testing of the Out-of-Step Protection at Mongolian Transmission System

Modern distance relays have integrated numerous protection functions, including power-swing blocking and out-of-step or pole-slip tripping functions. The main purpose of the power-swing blocking function is to differentiate faults from power swings and block distance or other relay elements from operating during stable or unstable power swings. Most power-swing blocking elements are based on traditional methods that monitor the positive sequence impedance rate. The required settings for the power-swing blocking elements could be difficult to calculate in many applications, particularly those where fast swings can be expected. For these cases, extensive stability studies are necessary to determine the fastest rate of possible power swings. This paper presents a detailed step-by-step method for settings calculation of out-of-step (OOS) protection, both blocking and tripping functions considering a generic two-source system. Then the method is applied to define the protection relay settings installed at the interconnection between the Russian and Mongolian power systems, as it is crucial to feed the demand-rich Mongolian power system. In this paper, a specific impedance method is used for defining the OOS protection settings. This paper innovates by testing the settings using the recordings of the major events of 15 September 2018 in two approaches: hybrid co-simulation and cyber-physical. Both tests have demonstrated the appropriate performance of the proposed settings and proving the proposed methodology works appropriately.

Rotating negative-sequence phasors for blocking and unblocking the distance protection during power swings

When power swings occur in transmission lines, the apparent impedance seen by the distance relay can shift toward the protection zone. This may result in unwanted trips in the protection system. This study proposes novel algorithms for detecting power swings and performing power swing blocking (ANSI 68) and unblocking through fault detection during power swings. The algorithms are free of settings and apply mathematical tools employed in commercial relays, such as the Fourier filter and symmetrical components. They are based on an analytical solution originally proposed in this study that demonstrates that negative-sequence phasors present a rotating behavior during a power swing, which can be used as a fundamental principle for power swing detection. The IEEE 9-bus electrical system is implemented in Matlab/Simulink to validate the proposed algorithms. The results show that the proposed algorithms effectively achieve blocking through power swing detection and achieve unblocking through fault detection. The latter function is shown to perform better than two algorithms available in the literature.

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

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.

Power Swing Blocking Algorithm based on Real and Reactive Power Transient Stability

Power swing due to the disturbance in the power system is a cause of the untrue operation of protective elements. Previously, many blackouts have been perceived and recorded due to reactive power mismatch problems, active power mismatch problems, and system venerability. The power system stability is usually disturbed due to the sudden loss of transmission lines, generators, and transformers. The present work proposes the concept of apparent power transient stability due to the transient disturbance. By considering that concept, we propose a power swing blocking algorithm to prevent mal-operation of distance relay. The proposed algorithm uses the relative frequency between the sending end bus and system standard frequency with simultaneous measurement of voltage decay of the transmission line. We have implemented the proposed algorithm on a single machine infinite system (SMIB) and the IEEE-9 bus system to compare the power swing detection and blocking performance with mho type out of step relay in different power swing conditions. In the end, results show the accurate performance, simplicity, reliability, and correct co-ordination of the proposed relay with distance relay, which ultimately solved the issue of mal-operation of zone-3 distance relay during complex power swing conditions.

An accurate technique for supervising distance relays during power swing

Power swing is a power system transient phenomenon that arises due to several reasons including line switching, line outage, sudden increment or decrement in load, faults, etc. Unnecessary tripping during power swing and unnecessary blocking for faults occur during power swing result in distance relay maloperation. Several cascaded outages and major worldwide blackouts have occurred due to maloperation of distance relays. This paper proposes a technique for supervising distance relays during power swing. The proposed online technique discriminates real faults and power swing accurately. It relies on constructing a locus diagram for the current and voltage differences (∆I-∆V) between the two ends of the protected line. The locus is estimated at every power frequency cycle to continuously monitor the state of the line by utilizing the synchrophasor measurements at the sending and receiving ends of the line. The proposed technique is tested for two-area, four-machine power system under faults at different locations of zone-1 and zone-2 regions of distance relays, fault resistances, fault inception angles and slip frequencies using MATLAB software. The simulation results proved the superior improvement of distance relay performance for handling power swing blocking and unblocking actions.

A New Model of Numerical MHO Distance Relay Associated with Power Swing Detector

In conventional transmission line protection, a distance relay is used to provide the primary as well as backup protection. The voltage and current phasors measurement needed by the distance relay for determining the impedance may be affected by the power disturbances such as power swing. Consequently, this power swing may cause mal-operation of Zone three distance relays which in turn may affect on the reliability of the whole protective scheme. Many power swing blocking functions (PSB) have been developed to mitigate these effects. In this paper, a new model of Mho distance relay with dual-quadrilateral power swing detection characteristic has been developed and implemented first in PC using LabVIEW, then tested using Power System Simulink Model under different faults and power swing conditions. Finally, the relay prototype has been realized using acquisition card NI USB-6009, which acquires real-time signals of the currents and the voltages, processes them digitally and outputs tripping or blocking signal to the circuit breaker. The obtained results show that the relay provides good discrimination between a fault and power swing condition.

A novel fast power swing blocking strategy for distance relay based on ADALINE and moving window averaging technique

A novel fast power swing blocking strategy for distance relay based on ADALINE and moving window averaging technique