Single-pole Tripping Research Articles

PMSG-based wind farm high-voltage ride-through improvement for single-pole tripping of circuit breakers

For transient single phase-to-ground (SPG) faults in transmission lines, single-pole circuit breaker (SPCB) operation can improve system reliability. This issue is more critical in transmission lines emanating from wind farms (WFs). In the large-scale WFs, the grid codes necessitate that wind generation remains in operation during the transmission line faults. For this purpose, the grid codes focus on the development of fault-ride-through (FRT) requirements. In this paper, it is shown that after the SPCB operation, the terminal voltage of the permanent magnet synchronous generator (PMSG)-based wind turbine (WT) rapidly increases and may cross the high-voltage ride-through (HVRT) boundary. Therefore, the WT terminal overvoltage after the SPCB operation may result in undesirable tripping of the WT. The obtained results in this paper show that in most cases both the coupled and decoupled sequence controllers of the WT converter equipped with the FRT requirements are not able to improve the HVRT performance after the SPCB operation. To enhance the HVRT performance of PMSG-based wind turbines after the SPCB operation, a dc-link chopper controller is proposed. EMTP-RV simulation results on the IEEE 118-bus and 5-bus systems show the success and effectiveness of the proposed method.

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.

A new fault type classification method in the presence of inverter-based resources

Fault type classification is a critical stage in modern distance relays for activating the effective phase and ground distance elements. It is also used for some supplementary functions such as single-pole tripping and reclosing, teleprotection, and fault location. Traditional fault type classifiers are based on the symmetrical or superimposed components of the current signal. However, owing to the unconventional behavior of inverter-based resources (IBRs) compared to the synchronous generators, traditional methods are not reliable in the presence of IBRs. For example, modern grid codes impose some restrictions in terms of injected current during asymmetrical fault which put the accuracy of conventional fault classification methods in danger. Fault resistance could also affect the accuracy of fault type classification method. In this paper, first, the fault current signature of IBRs is analytically derived. Then, impacts of modern grid code and fault resistance on the conventional fault classification are properly evaluated by executing some simulation studies. Finally, a new fault classifier is proposed which is based on symmetrical components of the local voltage and current during asymmetrical faults. The proposed classifier presents a satisfactory degree of security in the faulted phase identification in the presence of IBRs under different host grid codes. Performance of the proposed method is properly analysed with different simulation scenarios such as different fault locations, fault resistances, pre-fault condition, test systems, and host grid codes in PSCAD/EMTDC software.

Discrimination between in-zone and out-of-zone faults during power swing condition using synchrophasor data

A new algorithm to discriminate between in-zone fault and out-of-zone fault conditions under power swing condition for wind/synchronous generators (WG/SG) integrated power transmission network is presented in this paper. The proposed algorithm is based on the calculation of a transmission line positive sequence power loss index, derived by calculating the absolute difference between the calculated and measured values of positive sequence real power loss. The authenticity of the proposed technique is verified by performing Hardware-in-Loop (HIL) simulation in the Real-Time Digital Simulator (RTDS) framework along with physical Phasor Measurement Units (PMUs), Phasor Data Concentrator (PDC), Global Positioning System (GPS) clock, and voltage and current amplifiers. Various events such as power swing, in-zone (including close-in and high resistance) faults during power swing and out-of-zone faults during power swing are simulated by modeling WG/SG integrated IEEE-9 bus system in RSCAD (Real-Time Simulator Computer-Aided Design) framework. The single pole tripping, impact of noise and CT saturation on the proposed algorithm is also analyzed. The proposed algorithm offers accurate discernment between in-zone and out-of-zone faults during power swing conditions. The results obtained reveal increased sensitivity and improved distinguishing capability of the proposed algorithm in contrast to those of many other approaches proposed in the literature.

A Fault and Islanding Detection Scheme using Differential Positive Sequence Power Angle for a Microgrid

Implementation of distributed generation (DG) fault and islanding detection in a microgrid are two difficult jobs to complete. Efforts by many researchers to develop solutions to these a kind of challenges are ongoing. Still, there is hardly any scheme that can detect and distinguish both the fault and islanding events. To detect and differentiate between fault and islanding events, this article presents a Differential Positive Sequence Power Angle (DPSPA)-based protection technique. The scheme is widely examined considering different working conditions of a microgrid such as DG disconnection, DG penetration, different fault parameters like fault type, fault resistance, fault location, fault inception angle, fault during single-pole tripping (STP), simultaneous faults, and evolving faults. Tests were also performed for non-fault cases like load switching, capacitor switching, sectional cut-off, DG disconnection, and impact of noise and sampling frequency. Furthermore, the scheme’s outcomes have been compared to that of recent protection schemes. Finally, using the OP4510 real-time simulator, the proposed approach is validated in an online environment. The results show that the proposed DPSPA-based scheme can be a notable scheme to protect a microgrid in a wide variety of situations.

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.

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.

A technique for detection of islanding in a microgrid on the basis of rate of change of superimposed impedance (ROCSI)

Improper detection of islanding situation of a microgrid leads to undesirable mode of operation which causes power quality issues, reclosing failures, and serious equipment damage. Therefore, detection of islanding is a crucial challenge for protection schemes in the microgrid. In this work, a new islanding detection technique based on rate of change of superimposed impedance (ROCSI) is proposed. The voltage and current signals measured at PCC are used to estimate the impedance (Z). This estimated impedance is used to calculate the value of index (M), which is used to discriminate between islanding and non islanding events. To test the efficacy of proposed islanding detection technique, different islanding events (IE) and non islanding events (NIE) are created on modified IEEE 13 bus system integrated with two 2 MW solar photo voltaic distributed generations (PVDGs). The entire system is modelled and simulated on MATLAB/SIMULINK environment. Proposed islanding detection technique clearly identifies the IE during different active power mismatch, reactive power mismatch conditions and different quality factor loads. It also clearly identifies the NIE during load switching, single pole tripping, feeder disconnection, faults, and adjacent DG disconnection.

Adaptive distance relay algorithm to detect and discriminate third zone faults from system stressed conditions

This paper presents an adaptive approach for distance relay third zone setting. The proposed method uses variational mode decomposition (VMD) approach to decompose the local end current signal into different modes. The signal extracted from the third mode is used to calculate the energy index. The apparent impedance and energy index are used to detect symmetrical and asymmetrical faults in the third zone of the distance relay. The proposed logic also helps the distance relay to operate securely during power swing, voltage instability, load encroachment, generator outage, line outage, and single-pole tripping. The effectiveness of the proposed method is tested using the simulated data generated from the IEEE 39-test bus system model and Indian Power network. EMTDC/PSCAD software is used for simulating the models. Results ensure that the presence of noise in the signal, high resistance fault path and higher sampling frequency has a negligible impact on the performance of the proposed method.

Grey wolf optimization-tuned convolutional neural network for transmission line protection with immunity against symmetrical and asymmetrical power swing

The similar current–voltage profile during power swing and fault quite often leads to maloperation of distance relays. As compared to symmetrical power swings, discriminating a swing scenario from a fault becomes more challenging during asymmetrical swings arising due to single-pole tripping. Unlike symmetrical power swings, the presence of zero-sequence and negative-sequence current during asymmetrical swing scenarios hinders the application of classical power swing blocking schemes. In this regard, a convolutional neural network (CNN)-based protection scheme has been proposed in this paper, which, in addition to detecting, classifying, and locating faults, is also able to discriminate between power swing (both symmetrical and asymmetrical) and faults. The discrimination avoids possible maloperation during the non-faulty stressed conditions, thereby overcoming the limitation of the existing protection scheme. With the convolutional neural network, the raw signals are directly fed to the classifier, thus avoiding the computational cost associated with feature extraction in time and frequency domains. With the aim of achieving improved input–output mapping capability of CNN for larger datasets, an evolutionary optimization technique, i.e., grey wolf optimization, has been utilized for determining the optimal values of CNN tuning parameters. The performance of the proposed scheme has been extensively validated for a wide range of fault and power swing conditions in terms of standard indices, i.e., dependability, security, and accuracy. The effectiveness of the proposed scheme has also been evaluated for practical setting by performing real-time simulation on OPAL-RT digital simulator.

An integrated scheme for a directional relay in the presence of a series-compensated line

This paper presents an integrated method to identify the fault direction in the presence of a series compensator via also identifying the power flow direction. The presented method relies on monitoring both measured angle of the positive-sequence (PS) currents and magnitude of PS voltage. The change of PS voltage magnitude is used to detect the current inversion case. The presented criteria depend on the power flow direction before the fault occurrence. Therefore, a power flow direction identification method is presented using only the change of the phase angle of the PS current. Different system configurations are investigated to test the reliability of the proposed protection scheme (PPS). The power and protection systems’ configurations contain different capacitor ratios leading to current and voltage inversion scenarios, reversing the power flow direction and single-pole tripping. Simulation experiments conducted via the software ATP-EMTP has shown the proper operability of the PPS.

Amplitude based directional relaying scheme for UPFC compensated line during single pole tripping

This work, introduces a directional relaying technique based on amplitude directional discriminating (ADIS) factor for UPFC compensated high-voltage transmission lines during faults in the presence of single-pole-tripping (SPT) condition. After computation of positive sequence superimposed components of voltage and current signals, ADIS has been calculated for accurate fault direction discrimination. The feasibility and practicability of the proposed technique have been realized by simulating the single-circuit and double-circuit system using EMTDC/PSCAD under different adverse power system conditions. Least square method (LSM) has been used to estimate the fundamental components. The performance of various existing angle based directional relaying methods have been analysed considering SPT, in presence of UPFC in the single-circuit/double-circuit power system network and have been compared with proposed amplitude-based technique. The graphical illustration and analytical comparison of ADIS with widely used angle based techniques clearly exhibit its consistency, robustness and accuracy in estimating the direction of fault during SPT.

Wide-Area Backup Protection Against Asymmetrical Faults Using Available Phasor Measurements

This paper proposes a robust and computationally efficient wide-area backup protection (WABP) scheme against asymmetrical faults on transmission systems using available synchronized/unsynchronized phasor measurements. Based on the substitution theorem, the proposed scheme replaces the faulted line with two suitable current sources. This results in a linear system of equations for WABP, with no need of full system observability by measurement devices. The identification of the faulted line is attributed to the sum of squared residuals ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SoSR</i> ) of the developed system of equations. To preserve accuracy, the scheme limits the calculations to the assessment of the negative-sequence circuit of the gird. Relevant practical aspects that have not been properly addressed in the literature, namely the non-simultaneous opening of circuit breakers (CBs) and their single-pole tripping for single-phase to ground faults are investigated. The linearity of the formulations derived removes concerns over convergence speed and potential time-synchronization challenges. The proposed scheme is able to identify the faulted line and retain this capability for hundreds of milliseconds following the fault inception. More than 20 000 simulations conducted on the IEEE 39-bus test system verify the effectiveness of the proposed WABP scheme.

Positive-Sequence Component Based Directional Relaying Algorithm for Single-Pole Tripping

This paper addresses positive-sequence based protection scheme for series-compensated high-voltage transmission lines during faults in the presence of single-pole tripping (SPT) condition. Directional relaying algorithm based on the angle difference between fault and pre-fault positive-sequence current phasor has been proposed to estimate the fault direction during SPT in transmission lines. The performance of the proposed method has been evaluated by simulating the single-circuit system using EMTDC/PSCAD for various fault scenarios considering compensated and uncompensated transmission line. Discrete Fourier transform technique has been used to estimate the fundamental components. The outcome of different existing conventional directional relaying techniques has been analysed considering SPT, in the presence and absence of voltage and current inversion in the compensated/uncompensated system and compared with the proposed technique. To test the ability of the proposed classifier, the WSCC 9-bus system with capacitor switching and power swing has been tested. Some abnormal operating conditions have also been considered to prove the robustness of the proposed scheme. Simulation studies show that the fault direction estimation algorithm efficiently identifies the direction of fault. The performance of the algorithm shows its consistency and accuracy in estimating the direction of fault during SPT.

Distance Protection During Asymmetrical Power Swings: Challenges and Solutions

It is commonly assumed that power swings are symmetrical phenomena that impose almost identical effects on the three-phase voltages and currents of the power system. However, there is another type of power swings which is asymmetrical and occurs mainly during single-pole tripping. In the nowadays heavily loaded power systems, the likelihood of occurrence of this phenomenon is increased considerably. Although the effects of symmetrical power swings on distance protection are widely analyzed in the literature, asymmetrical power swings have been less studied so far. This paper focuses on this type of power swings and their effects on distance protection. Besides, two new techniques are proposed to detect faults during asymmetrical power swings and enhance performance of power swing blocking schemes. The first technique is based on the rate of change of zero sequence current, while the second one is based on the magnitudes of voltage and current in each phase, as well as their relative phase angle. The presented analyses and proposed methods are validated using two benchmark test systems and promising results are obtained.

Fault‐swing discrimination using Hilbert–Huang transform integrated discrete teager energy operator

In this work, a fault detection methodology during power swing is demonstrated. Modern distance relays are embedded with power swing blocking (PSB) function to preserve the security and reliable operation of power system during swing. However, the operation of PSB should be unblocked and let the distance relay allow to operate for any fault during swing. However, sometimes, distance relay unable to make a proper discrimination between swing and fault event leading cascading failures. In order to accomplish the fault detection task, first online empirical mode decomposition is used and processed through Hilbert-Huang transform to compute the amplitude and instantaneous frequency of that signal. Next, discrete teager energy approach is applied to estimate the teager energy. The energy operator functions as a reliable index for fault detection task during power swing. To evaluate the performance of the proposed method, different power system structures are considered and simulated using EMTDC/PSCAD. Results for current transformer saturation, single-pole tripping, and in presence of noise are provided. The response of the proposed method is compared with the conventional and existing methods. Results and comparative assessment reports demonstrate that the method is more efficient and robust in maintaining both selectivity and dependability.

Directional relaying in presence of STATCOM during single pole tripping

Static synchronous compensator (STATCOM), a shunt type flexible AC transmission system device, is used to control the voltage at different locations within a power system by absorbing/injecting reactive power. The dynamic control action associated with the operation of STATCOM in both capacitive and inductive modes is the reason for varying system condition and failure of different relaying schemes. Directional relaying is affected by the reactive current contributed by STATCOM in wide range of inductive to capacitive mode of operation. Further, single pole tripping (SPT) condition during STATCOM operation leads to mal-function of the directional element due to phase change in sequence components of voltage and current. In this study, directional relaying is addressed for different types of faults in the presence of STATCOM connected at different locations during single phase auto reclosing period. Proposed directional relaying technique is based on the phase angle between positive sequence fault and pre-fault apparent powers. Performance of the proposed scheme has been investigated for different types of faults for single and double circuit lines during SPT using simulated data of different power networks using PSCAD/EMTDC software. A comparative study is also carried out to verify the performance of the proposed scheme for different STATCOM operating conditions.

Adaptive α ‐plane line differential protection

Alpha plane ( α -plane)-based differential relay protecting a transmission line uses the ratio of the current phasors of both ends and has numerous advantages. Such an approach either uses phase or sequence components of currents. For a normal operating condition and external fault, the ratio remains within restraining region in the α -plane. During high resistance internal fault, the computed ratio at times lies inside the restraining region resulting misoperation of the technique. The scheme which uses sequence components of the currents has limited performance for single pole tripping and line impedance unbalance conditions. In this study, two features: phase angle between voltage and current and magnitude of change in currents of both ends of the line supplement the relay in identifying an internal fault. This improves the performance of phase current-based α -plane relay. The proposed method is tested for Western Electricity Coordinating Council (WSCC) 9-bus and two source equivalent system and results for various cases show improved performance.

Synchrophasors assisted protection scheme for the shunt‐compensated transmission line

This study presents synchrophasor assisted protection scheme for the protection of long transmission line compensated with shunt flexible AC transmission system (FACTS) device. With the advancement in synchrophasor technology, data communication medium, and wide area measurement system for transmission line protection, the differential protection scheme is a most suited scheme over the over-current, distance and directional protection schemes. The proposed scheme discriminate between internal and external fault using the time synchronised voltages and currents of both the terminal of the transmission line. The performance of proposed scheme has been evaluated on IEEE 12 bus FACTS benchmark power system model implemented in PSCAD/EMTDC. The measured voltage & current signals are pre-processed and phasors are estimated through DFT algorithm in MATLAB. The performance remains unaffected during wide variation in fault and system parameters including different line length and static var compensator rating. The test results confirm the selective, simplicity, high speed, sensitivity, and robustness of the proposed protection scheme. This scheme is also able to distinguish the faulty phase(s) from healthy phases, which enables the single-pole tripping option. Finally, comparative evaluation of the proposed technique with the existing protection schemes clearly shows its superiority.

An optimal/adaptive reclosing technique for transient stability enhancement under single pole tripping

This paper presents an integrated autoreclosure scheme (IAS) for transmission networks. The IAS operation is based on merging the functional advantages of the adaptive reclosing technique (ART) and the optimal reclosing technique (ORT). The ART identifies the nature of the fault, transient or a permanent fault, and determines the fault persistence time of a transient fault by analyzing the harmonic of the fault phase voltage using wavelet packet transform (WPT). The ORT is dependent on the load angle of the generators that minimizes the systems oscillation. The resulted information from the adaptive reclosing and the optimal reclosure timing units can effectively settled to achieve the optimum reclosing strategy that able to enhance power system stability. The proposed IAS is merited by an adaptive threshold level while needed information are captured from single end only. The IAS performance assessment compared to conventional reclosing schemes is carried out by using proposed voltage and speed indices. Examination of the proposed IAS is successfully achieved at different fault scenarios that involve various fault locations, inception angles, and representation of secondary arc characteristics. Added to that, the capability of the proposed scheme is confirmed considering the effects of shunt compensators, reactors and capacitors. Numerous simulation studies are emulated using MATLAB/SIMULINK on two test systems with different configurations. Simulation results indicate that the proposed reclosing method can enhance the transient stability.