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A new technique is proposed for loss of field (LOF) detection in synchronous generators (SGs). The proposed scheme employs the variations of SG angular velocity ∆ωφ and load angle ∆δφ to reach this goal, while the mentioned parameters are estimated through air gap flux estimation. The proposed scheme performance is evaluated using realistic simulation case studies based on IEEE C. 37. 102 standard compared to the conventional impedance‐based one. The obtained results show that the presented scheme excels the conventional scheme from speed and security viewpoints. Moreover, the estimation procedure of ∆ωφ and ∆δφ is experimentally validated by using a 10 kVA SG and the results demonstrate that the proposed technique can be easily set and implemented. [ABSTRACT FROM AUTHOR]

The transformerless single‐phase semi‐quasi‐Z‐source inverter (SqZSI) has a nonlinear gain curve and requires nonlinear sinusoidal pulse width modulation (NLSPWM) to achieve sinusoidal voltage at the output AC terminal. Although the SqZSI provides some advantages, for example, leakage current elimination, doubly grounded, low volume, and low cost, it needs nonlinear modulation control. The NLSPWM is relatively complex among single‐phase modulation methods and it is considered a disadvantage for this topology, so this paper presents a model‐driven processor programming method that facilitates the implementation of NLSPWM. The developed programming method utilizes a Blockset environment in MATLAB/Simulink to implement NLSPWM, and then the obtained model is compiled and directly uploaded to the ARM Cortex‐M4‐based STM32F4 processor. In this approach, there is no need for coding in C programming language, and only the Simulink mathematical blocks are used so it simplifies the implementation process. The same Simulink model used to model the inverter control is slightly edited for implementation, which accelerates the debugging cycle. Experimental results of 100 W SqZSI confirm the desired and accurate performance of this low‐cost method. The qualitative comparison of the processor programming methods and the performance comparison of the developed SqZSI based on this approach verify the simplicity of implementation. [ABSTRACT FROM AUTHOR]

An invasive diagnostic technique is proposed in this article for the detection and discrimination of turn-to-turn faults in the stator and rotor windings of synchronous machines during the startup period. For this purpose, search coils are installed in the machine to sense the rotational magnetic field along the air-gap circumference, while the difference in the related induced voltages (differential voltages) reveals its distortion, using it as a criterion for the detection of the faulty condition. Nevertheless, the rotor speed is a time-variant parameter, which changes from zero at the starting instant up to its rated value at a synchronous speed. Consequently, during the generator startup, the frequency of the induced voltages in the search coils needs to be updated continuously for obtaining reliable values for the differential voltages. A simple method is presented to achieve this goal by detecting the sequential zero crossing of the voltage waveforms. The proposed method is verified through simulation and experimental results. They show that the proposed diagnostic technique is capable of detecting and discriminating stator and rotor turn-to-turn faults during the machine startup period, both in generating and motoring conditions, with suitable accuracy and security. In addition, the region of stator turn-to-turn faults can be easily identified. [ABSTRACT FROM AUTHOR]

The impacts of the static synchronous compensator (STATCOM) on the traditional loss of excitation (LOE) protection are investigated in this article. To do a comprehensive study, a common and realistic excitation system is developed for the generator by employing the phase-domain model of the synchronous generator accessible in the real-time digital simulator. Using such a model, the LOE phenomenon is realistically studied in accordance with IEEE Standard C37. 102-2016, while the generator dynamics along with the LOE relay performance are investigated through different types of partial and complete LOE events. It is shown that in the presence of STATCOM, two major impacts on the generator and its LOE protection can be expected: 1) it imposes an additional time delay on the relay to detect the LOE failures, which depends on the generator initial loading and the type of LOE failure and 2) it might lead the generator to reach a new stable operating point without experiencing a loss of synchronism condition, during an improper changeover from automatic voltage regulator to manual voltage regulator operating mode. The related consequences for both of the impacts are discussed in this article, and some solutions are suggested to deal with the probable negative aspects. [ABSTRACT FROM AUTHOR]

An efficient online flux‐based diagnostic approach is proposed to detect turn‐to‐turn faults in the stator and rotor windings of wound rotor induction machines, at an early stage of development, which can be applied in the online mode. Some flux sensors are installed in the stator slots to detect the rotational magnetic field at various positions along the air‐gap circumference. These sensors measure the flux linked to all winding coil groups, in the three phases. Any fault occurring either in the stator or rotor windings will disturb the air‐gap flux and create an asymmetry in the rotational magnetic field, which is detectable through the difference of the induced voltages in the corresponding flux sensors. The proposed diagnostic technique is evaluated by finite element analysis as well as by multiple experimental tests. The obtained results show that such invasive technique is able to detect and discriminate various faults in the stator and rotor windings with high accuracy, low calculation burden, proper sensitivity and appropriate robustness in the face of machine load level variations. [ABSTRACT FROM AUTHOR]

A new approach for generator loss of field (LOF) protection is proposed by estimating the field current based on the generator measurable parameters. The main idea of the proposed approach is that a significant difference will be created between the measured excitation and the estimated field currents during LOF occurrence. A differential index is introduced to monitor such difference and consequently to detect LOF failures. A detailed and realistic field circuit is considered for the generator by using the phase-domain model of the generator in the real-time digital simulator, while different types of LOF events can be simulated through such model as well. The obtained results show that the presented technique can detect various types of LOF events much faster than the conventional impedance-based scheme. Moreover, it exhibits more security than the conventional technique in the face of power system disturbances (e.g., stable power swing and out-of-step conditions). [ABSTRACT FROM AUTHOR]

A real-time realistic framework for synchronous generator loss of field (LOF) protection studies is suggested in this paper by using the real-time digital simulator, which allows the user to realistically model the generator field supply circuit. By using such framework, the performance of LOF protection algorithms can be comprehensively evaluated in the face of the various LOF events including the short circuit and two types of the open circuit events, while the open circuit occurrence cannot be studied in the conventional simulation programs. The obtained results demonstrate that the generator dynamics are significantly different in the face of various LOF failures and then all of them must be regarded to develop the new LOF protection algorithms. By using the suggested framework, the performance of some recently proposed schemes along with the conventional impedance and the admittance relays are comprehensively evaluated. The obtained results from applying the various LOF failures show that, against the conventional relays, the new schemes cannot detect all types of LOF failures and so, they do not have enough reliability. [ABSTRACT FROM AUTHOR]

A new air-gap flux-based technique is proposed in this paper for turn-to-turn fault (TTF) detection and defective region identification, which is implemented in line-connected and inverter-fed induction motors. Some search coils (SCs) are used to measure the magnetic flux in various air-gap regions of the mentioned motor. The induced voltages in the SCs reveal the configuration of the rotational magnetic field (RMF) along the stator inner circumference to assess the symmetricity level of the flux distribution at each time instant. The RMF asymmetric distribution can be detected by comparing the induced voltages in various dual SCs (which under healthy conditions must sense identical magnetic flux) to detect TTFs and identify the faulty region as well. The proposed method is verified through finite element simulations and also by carrying out several experimental tests. Despite the fact that the proposed method is an invasive diagnostic technique, significant sensitivity and robustness in the face of unbalanced voltage sources and/or loading level are compelling evidence to use it for TTF detection at an incipient stage. The capability of the proposed technique to identify the faulty phase and the related region in the stator is another advantage of this invasive method, which cannot be ignored. [ABSTRACT FROM AUTHOR]

Power transformer, as one of the most important apparatus in power system, must be protected against the turn-to-turn faults. Although the various methods based on the terminal currents and/or voltages have been presented for transformer protection, the flux-based methods can be used to achieve the more accurate, sensitive, and secure results. Since the symmetrical form of the magnetic flux distribution will be disturbed due to any fault occurrence in the transformer windings, it can be considered as an appropriate criterion to achieve a suitable protection algorithm, which can detect the fault occurrence and identify the faulty phase/region. In this paper, a new leakage flux sensor is introduced and then a flux-based technique is proposed to detect and identify the faulty phase in transformers to apply in online conditions. By using the proposed technique, the faulty region can be identified in offline conditions, as well. The experimental results (which are done on a distribution transformer) show that this technique is secure in the face of overfluxing and transformer energizing conditions and can detect turn-to-turn faults with high sensitivity. Moreover, tap changer operation, imbalanced loads, and/or unsymmetrical voltage sources cannot influence the proposed technique security. [ABSTRACT FROM PUBLISHER]

Loss-of-field (LOF) phenomenon in synchronous generators may cause equipment damage and voltage drop in the power system, which can be terminated to a blackout. Conventional schemes, which detect LOF on the basis of the measured impedance from the generator terminal viewpoint, have some major drawbacks such as low speed, complicated setting procedure, and unsecure performance in the face of similar phenomena, e.g., stable power swing. In this paper, different electrical quantities of the generator including terminal voltage (V), current (I ), active (P) and reactive power (Q), and power angle (δ) variations are studied to achieve a secure technique for LOF protection in synchronous generators. Comprehensive studies show that a simple criterion based on polarities of V, Q, and δ variations is accessible to achieve this goal, which does not need a complicated procedure to set it. To evaluate the performance of the proposed algorithm, some cases are simulated on sample power systems under various operating conditions. Also, superiority of the proposed algorithm in comparison with the other schemes is proven by the obtained results, as well. Moreover, the proposed technique is experimentally tested by using some 2-kVA laboratory generators to detect LOF. [ABSTRACT FROM AUTHOR]

• Transformerless SqZSI with common-ground and minimum leakage current features is an attractive and cost-effective option as a PV microinverter. • SqZSI injects second harmonic and DC components under certain conditions, which is undesirable in terms of published power-quality standards. • The experimental study on power quality improvement of this family of inverters (SqZSI) is currently limited. • Closed-loop compensation methods based on well-known linear control techniques e.g. PI & PR controllers can mitigate extensively the power quality issues. The transformerless single-phase semi-quasi-Z-source inverter (SqZSI) provides several advantages over classical PWM converters. Reduced or eliminated leakage current, high power density, and low cost are important features making this topology an attractive choice for PV micro-inverter applications. Two drawbacks of this topology are DC and second harmonic injection in the output AC port, which in some cases prevent the fulfillment of standard requirements. To alleviate this power quality issue, four novel harmonic mitigation algorithms based on PI and PR controllers are proposed, analyzed, and experimentally verified with the 90 W SqZSI in this paper. Moreover, a modified modulation reference waveform strategy is introduced. Consequently, the converter performance, in terms of total harmonic distortion (THD V) is achieved at about 1.27% under full power load. Also, in this paper, the non-ideal state-space model of the SqZSI with the effect of the equivalent series resistance of inductors is developed and the generation origin of DC and second harmonic component is analyzed based on the obtained model. The achieved results confirms the significant THD reduction by more than 75%, the DC component suppression, the second harmonic mitigation, and the power quality improvement. [ABSTRACT FROM AUTHOR]

Loss of field (LOF) phenomenon in synchronous generators may cause serious damages and voltage drop in the power system, which can result in a blackout. Conventional methods, which detect LOF on the basis of the measured impedance from terminal viewpoint, are slow and may exhibit mal‐operation in the face of other phenomena, e.g. stable power swing (SPS). In this paper, a novel technique is proposed to detect LOF in synchronous generators on the basis of some electrical quantities variations including voltage of terminal (V), current (I), active power (P), reactive power (Q) and power angle (δ). To evaluate the performance of the proposed algorithm, some cases are simulated under various operation conditions. Obtained results show that this algorithm on the basis of V, Q and δ not only can be considered as a fast LOF detector in comparison with the conventional impedance‐based schemes, but also it is a robust and secure technique in the face of SPS and other power system disturbances. The proposed algorithm is tested by using an experimental setup including the laboratory synchronous generators, too. The obtained results show that the proposed technique can exhibit suitable performance in the actual conditions. [ABSTRACT FROM AUTHOR]

Monitoring of partial discharge (PD) and its progress as the main cause of the insulation deterioration process in power transformers can encompass valuable information about the related insulation condition and reveals degradation mechanisms. In this study, some simple sensors, which are made from a few turns wrapped around the transformer core, are used to detect PD signals. Moreover, a feasibility study is done to identify defective phase/region based on the captured PD signals waveforms through these sensors. The idea is implemented on a 50 kVA, 20 kV/400 V three‐phase transformer by injecting artificial and quasi‐real PD signals to different sections of HV windings. Also, various transformer connections are considered in the experimental studies to find the effect of them on the waveforms of the captured signals (e.g. peak‐to‐peak value and signal energy). The obtained experimental results show that small PDs (as low as 10 pC) is detectable by the mentioned sensors and defective phase can be identified in all of transformer connection cases. Furthermore, considering failure to identify defective regions by broadband analysis, a limited‐band approach is proposed through obtaining |H(s)| for the sensors. The results show that exact defective phase/region identification is feasible by selecting a frequency band compatible with IEC60270 recommendation. [ABSTRACT FROM AUTHOR]

Partial discharge (PD) is the most important factor in gradual insulation deterioration of high-voltage (HV) power equipment, and then PD trend monitoring is a great issue for their condition assessment. Impulsive high-frequency PD current/voltage signals can be detected by using electrical sensors, e.g. inductive/capacitive sensors. A comprehensive feasibility study is carried out to use the power frequency current transformers (CTs) that are already installed in medium voltage and HV electrical power systems instead of high-frequency CTs. To achieve this aim, frequency response of a sample protection CT is extracted experimentally and it is fitted to appropriate transfer functions to access the related frequency characteristics. Regarding improper CT frequency response and its extreme variations in different frequencies, reversed transfer function is obtained to apply to CT secondary signals for reconstructing CT input PD pulses. Two types of artificial PD pulses are examined to validate the proposed method and the experimental results show that power frequency CTs can be used for PD detection and measurement in some frequency bands. [ABSTRACT FROM AUTHOR]

Partial discharge (PD) is the most important factor in gradual insulation deterioration of high‐voltage (HV) power equipment, and then PD trend monitoring is a great issue for their condition assessment. Impulsive high‐frequency PD current/voltage signals can be detected by using electrical sensors, e.g. inductive/capacitive sensors. A comprehensive feasibility study is carried out to use the power frequency current transformers (CTs) that are already installed in medium voltage and HV electrical power systems instead of high‐frequency CTs. To achieve this aim, frequency response of a sample protection CT is extracted experimentally and it is fitted to appropriate transfer functions to access the related frequency characteristics. Regarding improper CT frequency response and its extreme variations in different frequencies, reversed transfer function is obtained to apply to CT secondary signals for reconstructing CT input PD pulses. Two types of artificial PD pulses are examined to validate the proposed method and the experimental results show that power frequency CTs can be used for PD detection and measurement in some frequency bands. [ABSTRACT FROM AUTHOR]

Since the internal turn‐to‐turn faults (TTFs), as a common cause of the transformer failures, result in minor changes on terminal currents/voltages, they maybe undetected by the conventional protective relays. In this study, a simple, sensitive and robust linkage flux‐based technique is proposed to protect the power transformers against TTFs. In this approach, some separated multi‐turn windings as search coils (SCs) have to be wrapped around the transformer core legs to sense the related passing flux. Since passing equal flux through a transformer core leg in normal condition induces equal voltages in the related SCs, variation of the induced voltages indicates the fault occurrence in that phase. Against the traditional differential protection schemes, current transformer error and saturation, tap changer operation, energising inrush current, over‐fluxing etc. cannot impact the proposed technique performance. Therefore, it can be introduced as a comprehensive protection technique for power transformers.To confirm the proposed technique performance, it is tested on a real 50 kVA, 20 kV/400 V three‐phase distribution transformer, in various conditions, too. [ABSTRACT FROM AUTHOR]

Current-transformer (CT) saturation phenomenon impacts the performance of the current-based protective relays and leads them to malfunction; so detecting and resolving such phenomenon are important issues in power system protection. This paper provides a modification for two well-established algorithms: 1) least square error and 2) artificial neural network to compensate and reconstruct CT's distorted secondary current waveform (CTDISCW). The effectiveness of an online algorithm is its operating capability in noisy environments and in the presence of travelling waves generated by any event. In addition, this algorithm must be stable against any normal variation in network structure. Then, both mentioned methods need to be modified to present proper results with an acceptable error in online conditions. In this paper, a real CT is considered to simulate, and a section of the Iranian power network is selected to generate CTDISCWs using the modeled CT, and to evaluate the proposed algorithms’ performance. [ABSTRACT FROM AUTHOR]

Internal turn‐to‐turn faults (TTF) are considered as a common cause of transformer failures. Such defects (especially minor TTFs) may result in minor changes in terminal currents/voltages as these are undetectable by conventional current and/or voltage‐based methods. In this study, a simple, sensitive and robust method is proposed to identify the TTF locations in power transformers by using core flux based technique. In this approach, a few turns must be wrapped around the transformer core legs to sense and detect the related core flux. Passing asymmetrical flux through a transformer core leg (due to a TTF) induces different voltages in the related sensors, which are located at different places. Variation of the core flux in the corresponding sensors indicates the faulty phase and the TTF location on that phase as well. The proposed technique is verified by some simulations and experimental tests. The obtained results show that the proposed technique successfully (i) detects all the TTFs, (ii) identifies the faulty phase, and (iii) specifies the faulty region on the related phase. Although the proposed method requires a few search coils to be installed on the transformer core legs, installing these thin wires will not change the transformer design significantly. [ABSTRACT FROM AUTHOR]

• Exact value of the parameters of both DDC components is estimated without any approximation. • The CT DDC component is estimated without the requirement of CT parameters. • Variations of the primary time constant and the sampling rate dose not influence the response of the proposed method. • Proposed method does not increase the sensitivity of the phasor estimation to off-nominal frequency conditions. • Anti-noise capability of the proposed method is high due to using averaging filter in DDC estimation processes. Fault current signals typically suffer from primary and secondary decaying DC (DDC) components due to the transient response of the power system and current transformer. On the other hand, the conventional phasor estimation method, discrete Fourier transform (DFT), is severely sensitive to these components and exhibits a significant oscillatory error. This paper proposes a new modification for the conventional DFT-based phasor estimation method to improve its performance in the face of fault current signals containing DDC components. The proposed method accurately estimates both DDC components using the fault current signal and an auxiliary signal generated using high-frequency modulation. The averaging filter is applied to the fault current and auxiliary signal over one cycle, and then parameters of the DDC components are estimated using its three successive results. In the last step, the undesired effect of DDC components is eliminated from DFT output. The efficiency of the proposed method is validated through fault current signals generated by mathematical formulation and simulated using the PSCAD/EMTDC environment. The overall analysis of the obtained results demonstrates that the new modification makes the DFT method robust against both DDC components. [ABSTRACT FROM AUTHOR]

Although wavelet transform decomposition has wide applications in the analysis of power system transients due to its multi-resolution analyzing nature, conventional transient simulation programs do not provide an effective inbuilt wavelet transform toolbox for online studies. This paper proposes the development and implementation of an Online Instantaneous Discrete Wavelet Transform Decomposition Toolbox ( IWTD toolbox) in ATP-EMTP software by its MODELS programming language. Integration of a powerful online discrete wavelet transform toolbox with alternative transient program makes this software highly functional especially with selectable different full and reduced order mother wavelets with definable reduction degree. The proposed toolbox provides a user-friendly interface with additional capabilities and features for ATP users. Numerous cases simulated and compared with the results of the well-known MATLAB Wavelet Toolbox have indicated that the proposed toolbox works reliably and accurately in the ATP-EMTP environment. [ABSTRACT FROM AUTHOR]

The issue of resilience in electrical distribution systems has been proposed increasingly with the frequent occurrence of natural disasters in recent years and the imposition of high costs due to widespread power outages. To date, various resilience indices have been proposed, some of which have been improved upon over time by extensive research, leading to more comprehensive indices. However, a standard index has not yet been approved and presented in this regard by international committees, despite the efforts made. The issue of resilience in electrical networks was examined by curve analysis index in more detail compared to other proposed indices, although it is not yet complete and should be investigated from various aspects and its shortcomings be eliminated. The present study aims to evaluate some fundamental obstacles in the "curve analysis" index and correct it in a new index called "Combining Investment and Reform" (CIR) index. Two issues of "costs in terms of investment and repairs imposed by the event" and "need to separate critical and non‐critical loads" are considered simultaneously in the proposed index. Finally, the capabilities of the proposed index are evaluated and compared in a sample electrical network in the face of events with different intensities. [ABSTRACT FROM AUTHOR]

The CuII complex bis[hydroxybis(pyridin-2-yl)methanesulfonato-κ3 N, O, N′]copper(II) hexahydrate, [Cu(C11H9N2O4S)2]·6H2O, (I), crystallizes in the space group P, compared with P21/ c for the anhydrous CoII analogue bis[hydroxybis(pyridin-2-yl)methanesulfonato-κ3 N, O, N′]cobalt(II), [Co(C11H9N2O4S)2], (II). However, both molecules sit on a crystallographic inversion centre and are thus very similar in appearance. Jahn-Teller elongation of the Cu-O bonds [2.347 (3) Å in (I) and 2.064 (2) Å in (II)] influences the S-O bond lengths, which are all around 1.455 (3) Å in (I) and 1.436 (2)-1.473 (2) Å in (II). [ABSTRACT FROM AUTHOR]

In the title compound, C36H25F6O2P2+·I3−, hydrogen-bonded [{( p-FC6H4)3PO}2H]+ dimers assemble along the crystallographic c axis to form channels that house extended chains of triiodide anions. Although the I-I bond lengths of 2.9452 (14) and 2.9023 (15) Å are typical, the inter-ion I...I distance of 3.5774 (10) Å is unusually short. A posteriori modelling of nonmerohedral twinning about (100) has been only partially successful, achieving a reduction in the maximum residual electron density from 5.28 to 3.24 e Å−3. The inclusion of two low-occupancy I-atom sites (total 1.7%), which can be interpreted as translational disorder of the triiodide anions along the channels, reduced the maximum residual electron density to 2.03 e Å−3. The minor fractional contribution volume of the nonmerohedral twin domains refined to 0.24 and simultaneous refinement of the inversion twin domains showed the crystal to be a 0.5:0.5 inversion twin. [ABSTRACT FROM AUTHOR]

The article discusses a study on Bis(methyltri-o-tolylphosphonium)octaiodide. Researchers reacted equimolar amounts of tri-o-tolyphosphine and methyl iodide at room temperature in dry dichloromethane and then 25 milliliters (ml) of anhydrous dichloromethane was added. The study showed that the octaiodide bonding distances are indicative of a di-iodide molecule and two tri-iodide anions.

The subject of resilience in electrical grids has become more popular among researchers in recent decades due to the rise of worldwide natural disasters such as floods, severe storms, snow, and hailstorms as well as the imposition of high costs resulted from widespread outages. Various methods have been proposed to improve the resilience of electrical grids under different conditions. In each work, the authors have validated their proposed method based on a function or metric they have defined to clarify its effect on improving the resilience of electrical grid. However, to date, there is no standardized metric for assessing the resilience of an electrical grid and providing the possibility to compare the many strategies discussed in different papers. This paper tries to explain the metrics that have been presented in various researches in this regard so far, and it compares these metrics from different aspects in order to determine the most comprehensive metric. [ABSTRACT FROM AUTHOR]

Here a new sensitive fault detection criterion is proposed, based on the stationary wavelet transform (SWT) decomposition components of the stator currents, for the online detection of stator winding turn‐to‐turn faults at an early stage of development. The energies of the desired detail components are calculated and the normalized Euclidean distance of the energy differences between the three phases is used as a new fault detection criterion. The robustness of the proposed technique against the presence of rotor turn‐to‐turn faults and loading variations is demonstrated. In addition, an adaptive threshold level as a function of the voltage unbalance factor is proposed to guarantee the robustness of the diagnostic technique against unbalanced voltage sources. Experimental results demonstrate the effectiveness and sensitivity of the proposed diagnostic approach for the detection of stator faults in line‐connected and inverter‐fed motors. [ABSTRACT FROM AUTHOR]

A portable flux probe is proposed and investigated in this article to detect turn-to-turn fault in the rotor poles of the high rated salient pole synchronous machines. The rotor circuit is fed by a low amplitude sinusoidal voltage source with a fixed voltage amplitude which has a frequency more than a few hundred Hz to achieve the higher reaction of the shorted turns on the faulty pole, which results in a significant reduction of the magnetic flux in the air-gap. Numerous simulations and experimental tests are carried out to investigate the proposed probe and the related technique performance to specify the faulty pole versus the number of shorted turns, applied frequency and probable eccentricity in the rotor position. The obtained test results show that all stable turn to turn faults (weak or heavy ones) can be specified easily by applying a portable sinusoidal voltage source with the frequency in the range of more than a few hundred Hz. The experimental test results validate that the flux density can be reduced to about zero in the faulty pole face, even in the case of one shorted turn in the sample machine. [ABSTRACT FROM AUTHOR]

A flux-based technique is proposed for the on-line detection, localization and discrimination of stator and rotor turn-to-turn faults in synchronous generators, using the measured air-gap rotational magnetic field. Simple magnetic field sensors (MFSs) are installed in the stator slots at different regions, and the corresponding induced voltages are measured. Several differential voltages are then obtained to give a picture of the rotational magnetic field symmetricity, whose distortions indicate the presence of the stator or rotor faults. The proposed diagnostic technique is presented in detail and validated initially by simulation results obtained with a finite element simulation package and afterwards through the experimental tests. The obtained results demonstrate that the proposed technique can be used to detect and discriminate stator and rotor turn-to-turn faults with appropriate sensitivity. In addition, the region of the stator turn-to-turn faults can be identified as well. [ABSTRACT FROM AUTHOR]

This paper presents a novel technique for the online detection of broken rotor bar(s) (BRBs) in induction motors, based on the analysis of the air-gap rotational magnetic field (RMF), being it indirectly sensed using the voltages induced in dual search coils installed in several stator regions. The induced voltages allow obtaining three differential voltages which reveal the symmetricity level of the mentioned field along the stator circumference. Under the presence of the broken bar(s), the RMF is disturbed by the rotor magneto-motive force, being these disturbances detected through the fundamental components of the differential voltages using a new time-domain analysis technique. The proposed diagnostic approach is verified by finite-element analysis and also by several experimental tests. A high sensitivity, robustness in the face of unbalanced voltage sources and motor load level variations are the main advantages of the proposed technique. Moreover, it is a secure method for BRB detection, easily implementable in low-cost digital signal processing units. [ABSTRACT FROM AUTHOR]

• Provide the number and capacity of truck-mounted mobile generators in order to achieve a certain percentage of the resilience parameter. • Introduction and application of the consolidation index and simultaneous examination of two parameters " cost (either of the type of investment or of the type of repairs imposed by the event)" and " unsupplied loads (with critical and non-critical load separation)". • Providing the "decision curve" and the possibility of optimal choice by the planner or policymaker to promote resilience according to the available budget. Electrical energy supply is a vital part of a modern network, so enhancing its resilience to natural hazards is of paramount importance. The present study aims to determine the number and capacity of truck-mounted mobile generators that can be utilized in electric power distribution networks to provide a certain level of resilience, taking into account the costs and revenues associated with their use. To this aim, a "consolidation index" is used, which is based on the "curve analysis index" and considers "cost (either of the type of investment or of the type of repairs imposed by the event)" and "lack of load supply (with critical and non-critical load separation)" simultaneously. Presenting a "decision curve" allows the planner or policymaker to perform the best by applying the amount of capital or budget at his/her disposal to improve a certain percentage of the resilience in the evaluated network. Finally, the effectiveness and efficiency results of the proposed method are shown in the modified IEEE 33-bus network. [ABSTRACT FROM AUTHOR]

In this paper, based on the CART technique and wide area measurement system (WAMS), a new scheme of wide area damping controller (WADC) is presented for inter-area oscillation in which each generator is equipped with an individual WADC which works based on the global inter-area signals. The proposed WADC scheme is an individual controller which uses angle and speed deviation of the center of inertia of the oscillating areas as global inter-area signals (GIS) (Δω COI , Δδ COI ). Each individual WADC consists of two CART1 and CART2 which perform as optimal gain estimators for estimating optimal gains K1 and K2 of the individual WADC of each generator. In fact, the proposed WADC scheme is an online and non-model based controller consisting of two CARTs which estimate optimal gains (K 1 , K 2 ) from which inter-area control signal (ICS) is produced for direct presentation to AVR of generators. In this scheme, for selecting the most effective generators for participating in damping control, a combination index (CI) is presented which is maximized by binary genetic algorithm (BGA) for achieving most damping. The proposed CI index consists of generation pattern and Thevenin impedance of generators. For this purpose, for online estimation of Thevenin impedance of generators, an online approach is presented in which by using three consecutive measurements Thevenin impedance of generators are evaluated. The proposed CARTs are trained off line and then in the real time working mode of the proposed approach by using online GIS signals estimate optimal gains K1 and K2 from which individual control signal is deveopled. The proposed control scheme is demonstrated on IEEE 39-bus test system with promising damping effect for inter-area oscillation. [ABSTRACT FROM AUTHOR]

• A novel controller based on the combination of a FOPID controller, a TID controller, and a 2DOF controller is proposed to rectify the ACE signal and consequently to improve the frequency response of multi-area power systems. • The AVR loop along with PSS is added to the LFC model to complete the LFC aim and considering the cross‐coupling of LFC with AVR. • A modified SCA (MSCA) is used to obtain the best controllers gains during disturbances. • The simulation studies are conducted on different power systems. • Sensitivity analysis is done to exhibit the robustness of the proposed LFC scheme against variations of the grid parameters. This paper presents a novel load frequency control (LFC) model for an interconnected thermal two-area power system in the presence of wind turbine generation and redox flow battery (RFB). The study model includes frequency and voltage excitation loops with needed interactions between them along with the power system stabilizer. A two-degree of freedom (2DOF)-based controller called 2DOF-Hybrid controller is developed as secondary controller in automatic generation control (AGC) to adjust the power outputs of generator and RFB. Also, the dynamic performance of the proposed controller in the RFB loop is evaluated. The Hybrid controller comprises a fractional-order proportional-integral-derivative (FOPID) controller and a tilt-integral-derivative (TID) controller. In order to obtain accurate and realistic results, the outputs of thermal power plants are restricted by considering the limitations of the governor dead-band and generation rate constraint. Since the controller performance depends on its parameters, these parameters are optimized using a modified sine–cosine algorithm (MSCA). The dynamic performance of the proposed 2DOF-Hybrid controller as secondary controller of the AGC loop is compared with integral-double-derivative (IDD), integral-tilt-derivative, proportion-integral–derivative (PID)-DD, 2DOF-PID, 2DOF-TID, and 2DOF-FOPID ones under different scenarios. In addition, the superiority of the MSCA is compared with benchmark metaheuristic methods including an SCA, a genetic algorithm, a particle swarm optimization, and a differential evolution. The sensitivity analysis is also carried out to show the robustness of the proposed controller versus the changes of the parameters. The simulation studies on two-area and New England 39-bus power systems are carried out to examine the advantage of the presented LFC scheme. A range of power system signals such as frequencies of areas, terminal voltages, and tie-line power flow is demonstrated to compare the controllers. The results disclose that the proposed LFC scheme provides better dynamic performance compared to other ones. Moreover, RFB modeling based on the proposed controller is superior to conventional RFB modeling in reducing the amplitude of the oscillations. [ABSTRACT FROM AUTHOR]

• Proposing a novel damping control strategy for GCSC to contribute to LFC. • Adopting a robust stability criterion for the proposed LFC scheme. • Evaluating the time delay impact on the performance of frequency regulation. • Applying the proposed method to multi-area power systems under various environments. • Comparing the proposed control strategy with integer/fractional order controllers. • Performing the sensitivity analysis to assess the robustness property. This paper addresses the application of the gate controlled series capacitor (GCSC) in coordination with automatic generation control (AGC) for providing better dynamic responses in interconnected multi-area power systems. A novel controller scheme called Hybrid controller for modeling the GCSC is proposed. The proposed control model consists of a fractional-order proportional-integral-derivative (FOPID) controller and a tilt-integral-derivative (TID) one. Optimized coefficients of the controllers are obtained by applying the Sine-Cosine algorithm (SCA). The delay in communication links as a common feature in wide area control of power systems may cause instability problem. So, a robust stability criterion is presented to estimate the maximum delay time which allows an AGC scheme embedded with the GCSC damping controller to retain stable. Comprehensive discussions are presented on a deregulated two-area power system and a traditional three-area one. Simulation results confirm that the proposed Hybrid controller is capable to achieve better dynamic responses and provide better coordination between the GCSC and AGC in comparison to the other coordinated controllers including PID-based GCSC-AGC, TID-based GCSC-AGC, and FOPID-based GCSC-AGC ones. Eventually, the sensitivity analysis is accomplished to assess the robustness property of the proposed controller against the variations of the parameters. [ABSTRACT FROM AUTHOR]