Showing papers on "Power-system protection published in 2012"

GECO: Global Event-Driven Co-Simulation Framework for Interconnected Power System and Communication Network

Abstract: The vision of a smart grid is predicated upon pervasive use of modern digital communication techniques to today's power system. As wide area measurements and control techniques are being developed and deployed for a more resilient power system, the role of communication network is becoming prominent. Power system dynamics gets influenced by the communication delays in the network. Therefore, extensive integration of power system and communication infrastructure mandates that the two systems be studied as a single distributed cyber-physical system. This paper proposes a power system and communication network co-simulation framework (GECO) using a global event-driven mechanism. The accuracy is tunable based on the time-scale requirements of the phenomena being studied. This co-simulation can improve the practical investigation of smart grid and evaluate wide area measurement and control schemes. As a case study, a communication-based backup distance relay protection scheme is co-simulated and validated on this co-simulation framework.

Optimizing the Roles of Unit and Non-unit Protection Methods Within DC Microgrids

Abstract: The characteristic behavior of physically compact, multiterminal dc networks under electrical fault conditions can produce demanding protection requirements. This represents a significant barrier to more widespread adoption of dc power distribution for microgrid applications. Protection schemes have been proposed within literature for such networks based around the use of non-unit protection methods. This paper shows however that there are severe limitations to the effectiveness of such schemes when employed for more complex microgrid network architectures. Even current differential schemes, which offer a more effective, though costly, protection solution, must be carefully designed to meet the design requirements resulting from the unique fault characteristics of dc microgrids. This paper presents a detailed analysis of dc microgrid behavior under fault conditions, illustrating the challenging protection requirements and demonstrating the shortcomings of non-unit approaches for these applications. Whilst the performance requirements for the effective operation of differential schemes in dc microgrids are shown to be stringent, the authors show how these may be met using COTS technologies. The culmination of this work is the proposal of a flexible protection scheme design framework for dc microgrid applications which enables the required levels of fault discrimination to be achieved whilst minimizing the associated installation costs.

A New Z-Source DC Circuit Breaker

Abstract: A novel type of circuit breaker is introduced for operation at medium-voltage dc with future naval ship power systems as a targeted application. The breaker utilizes a z-source LC circuit in order to automatically commutate a main-path SCR during a fault. Compared to existing dc circuit breakers, the z-source breaker features fast turn-off, simple control, and the source does not experience the fault current. The operation and analysis of the new breaker is presented. Component sizing is carried out for three medium-voltage power levels. Incorporation of the new breaker within a drive system is also explored. Laboratory validation is carried out on a low-voltage prototype.

Laboratory-Based Smart Power System, Part I: Design and System Development

Abstract: This paper presents the design and development of a hardware-based laboratory smart grid test-bed. This system is developed at the Energy Systems Research Laboratory, Florida International University. The hardware/software based system includes implementation of control strategies for generating stations, and power transfer to programmable loads in a laboratory scale of up to 35 kilowatts in ac power and 36 kW in renewable sources and energy storages. Appropriate software was developed to monitor all system parameters as well as operate and control the various interconnected components in varying connectivity architectures. The interconnection of alternate energy such as wind emulators, PV arrays, and fuel cell emulators are implemented, studied and integrated into this system. Educational experiences were drawn during the design and system development of this laboratory-based smart grid. The real-time operation and analysis capability provides a platform for investigation of many challenging aspects of a real smart power system. The design, development, and hardware setup of this laboratory is presented here in Part I of this paper. This includes component development, hardware implementation, and control and communication capabilities. Part II of the paper presents the implementation of the monitoring, control, and protection system of the whole setup with detailed experimental and simulation results.

Relyzer: exploiting application-level fault equivalence to analyze application resiliency to transient faults

Abstract: Future microprocessors need low-cost solutions for reliable operation in the presence of failure-prone devices. A promising approach is to detect hardware faults by deploying low-cost monitors of software-level symptoms of such faults. Recently, researchers have shown these mechanisms work well, but there remains a non-negligible risk that several faults may escape the symptom detectors and result in silent data corruptions (SDCs). Most prior evaluations of symptom-based detectors perform fault injection campaigns on application benchmarks, where each run simulates the impact of a fault injected at a hardware site at a certain point in the application's execution (application fault site). Since the total number of application fault sites is very large (trillions for standard benchmark suites), it is not feasible to study all possible faults. Previous work therefore typically studies a randomly selected sample of faults. Such studies do not provide any feedback on the portions of the application where faults were not injected. Some of those instructions may be vulnerable to SDCs, and identifying them could allow protecting them through other means if needed.This paper presents Relyzer, an approach that systematically analyzes all application fault sites and carefully picks a small subset to perform selective fault injections for transient faults. Relyzer employs novel fault pruning techniques that prune faults that need detailed study by either predicting their outcomes or showing them equivalent to other faults. We find that Relyzer prunes about 99.78% of the total faults across twelve applications studied here, reducing the faults that require detailed simulation by 3 to 5 orders of magnitude for most of the applications. Fault injection simulations on the remaining faults can identify SDC causing faults in the entire application. Some of Relyzer's techniques rely on heuristics to determine fault equivalence. Our validation efforts show that Relyzer determines fault outcomes with 96% accuracy, averaged across all the applications studied here.

Extended Topological Metrics for the Analysis of Power Grid Vulnerability

Abstract: Vulnerability analysis in power systems is a key issue in modern society and many efforts have contributed to the analysis. Recently, complex networks metrics, applied to assess the topological vulnerability of networked systems, have been used in power grids, such as the betweenness centrality. These metrics may be useful for analyzing the topological vulnerability of power systems because of a close link between their topological structure and physical behavior. However, a pure topological approach fails to capture the electrical specificity of power grids. For this reason, an extended topological method has been proposed by incorporating several electrical features, such as electrical distance, power transfer distribution, and line flow limits, into the pure topological metrics. Starting from the purely topological concept of complex networks, this paper defines an extended betweenness centrality which considers the characteristics of power grids and can measure the local importance of the elements in power grids. The line extended betweenness is compared with the topological betweenness and with the averaged power flow on each line over various operational states in the Italian power grid. The results show that the extended betweenness is superior to topological betweenness in the identification of critical components in power grids and at the same time could be a complementary tool to efficiently enhance vulnerability analysis based on electrical engineering methods.

A Novel Approach to Detect Symmetrical Faults Occurring During Power Swings by Using Frequency Components of Instantaneous Three-Phase Active Power

Abstract: Since distance relays are prone to interpret a power swing as a three-phase fault, they should be blocked during the power swing to prevent undesired trips. On the other hand, if any fault occurs during a power swing, they should be fast and reliably unblocked. Although unblocking the relay is straightforward in the case of asymmetrical faults by using the zero-sequence and/or negative-sequence component of current, detecting symmetrical faults during a power swing is still a challenge. This paper presents a novel method for detecting symmetrical faults occurring during a power swing. Based on the damping frequency component of 50 (or 60) Hz created on instantaneous three-phase active power profile after inception of a symmetrical fault, the proposed method will be able to detect the fault in less than one power cycle. This detection method can be readily implemented, and is immune to the power swing slip frequency, fault inception time, and fault location. To test the proposed method, several power swings and faults are numerically simulated in MATLAB/SIMULNK, and the simulation results show that the proposed method is sensitive as well as reliable.

A Markov-Transition Model for Cascading Failures in Power Grids

Abstract: The electric power grid is a complex critical infrastructure network. Its inter-connectivity enables long-distance transmission of power for more efficient system operation. The same inter-connectivity, however, also allows the propagation of disturbances. In fact, blackouts due to cascading failures occur because of the intrinsic electrical properties of this propagation and physical mechanisms that are triggered by it. In this paper we propose a stochastic Markov model, whose transition probabilities are derived from a stochastic model for the flow redistribution, that can potentially capture the progression of cascading failures and its time span. We suggest a metric that should be monitored to expose the risk of failure and the time margin that is left to perform corrective action. Finally we experiment with the proposed stochastic model on the IEEE 300 bus system and provide numerical analysis.

Methodology for a Security/Dependability Adaptive Protection Scheme Based on Data Mining

Abstract: Recent blackouts offer testimonies of the crucial role played by protection relays in a reliable power system. It is argued that embracing the paradigm shift of adaptive protection is a fundamental step toward a reliable power grid. The purpose of this paper is to present a methodology to implement a security/dependability adaptive protection scheme. The advocated methodology aims to reduce the likelihood of manifestation of hidden failures and potential cascading events by adjusting the security/dependability balance of protection systems. The proposed methodology is based on wide-area measurements obtained with the aid of phasor measurement units. A data-mining algorithm, known as decision trees, is used to classify the power system state and to predict the optimal security/dependability bias of a critical protection scheme. The methodology is tested on a detailed 4000-bus system.

Differentiating series and parallel photovoltaic arc-faults

Abstract: The 2011 National Electrical Code® requires PV DC series arc-fault protection but does not require parallel arc-fault protection. As a result, manufacturers are creating arc-fault circuit interrupters (AFCIs) which only safely de-energize the arcing circuit when a series arc-fault occurs. Since AFCI devices often use the broadband AC noise on the DC side of the PV system for detection and series and parallel arc-faults create similar frequency content, it is likely an AFCI device will open in the event of either arc-fault type. In the case of parallel arc-faults, opening the AFCI will not extinguish the arc and may make the arc worse, potentially creating a fire. Due to the fire risk from parallel arc-faults, Tigo Energy and Sandia National Laboratories studied series and parallel arc-faults and confirmed the noise signatures from the two arc-faults types are nearly identical. As a result, three alternative methods for differentiating parallel and series arc-faults are presented along with suggestions for arc-fault mitigation of each arc-fault type.

Short-Circuit Fault Protection Strategy for High-Power Three-Phase Three-Wire Inverter

Abstract: This paper proposes a four-stage fault protection scheme against the short-circuit fault for the high-power three-phase three-wire combined inverter to achieve high reliability. The short-circuit fault on the load side is the focus of this paper, and the short-circuit fault of switching devices is not involved. Based on the synchronous rotating frame, the inverter is controlled as a voltage source in the normal state. When a short-circuit fault (line-to-line fault or balanced three-phase fault) occurs, the hardware-circuit-based hysteresis current control strategy can effectively limit the output currents and protect the switching devices from damage. In the meantime, the software controller detects the fault and switches to the current controlled mode. Under the current controlled state, the inverter behaves as a current source until the short-circuit fault is cleared by the circuit breaker. After clearing the fault, the output voltage recovers quickly from the current controlled state. Therefore, the selective protection is realized and the critical loads can be continuously supplied by the inverter. The operational principle, design consideration, and implementation are discussed in this paper. The simulation and experimental results are provided to verify the validity of theoretical analysis.

Intermittent Fault Location in Distribution Feeders

Abstract: Due to the utilization of fundamental frequency, current impedance-based fault-location methods are able to locate only permanent and linear faults. The duration of the arc in low- and medium-voltage systems can be as short as a quarter of a cycle. This period, which is normal for intermittent faults, is insufficient for fundamental frequency-based fault-location algorithms. Therefore, available methods are not applicable for an intermittent arcing fault location. In this paper, a novel method is proposed for arcing fault location in radial feeders, utilizing time-based formulation considering the short duration of the faults. The advantage of the proposed method over available methods is its capability for locating faults using fewer samples, which is suitable for arcing faults as well as normal faults in the network. Also, different types of faults are taken into account in the proposed algorithm. The validity of the devised algorithm is studied within the PSCAD-EMTDC environment and the results obtained show good accuracy for arcing faults. The application of the proposed algorithm in real systems is based on the availability of measured voltage and current waveforms at one end of the network and knowledge of cable/line parameters (self and mutual impedances).

Current–Time Characteristics of Resistive Superconducting Fault Current Limiters

Abstract: Superconducting fault current limiters (SFCLs) may play an important role in power-dense electrical systems. Therefore, it is important to understand the dynamic characteristics of SFCLs. This will allow the behavior of multiple SFCLs in a system to be fully understood during faults and other transient conditions, which will consequently permit the coordination of the SFCL devices to ensure that only the device(s) closest to the fault location will operate. It will also allow SFCL behavior and impact to be taken into account when coordinating network protection systems. This paper demonstrates that resistive SFCLs have an inverse current-time characteristic: They will quench (become resistive) in a time that inversely depends upon the initial fault current magnitude. The timescales are shown to be much shorter than those typical of inverse overcurrent protection. A generic equation has been derived, which allows the quench time to be estimated for a given prospective fault current magnitude and initial superconductor temperature and for various superconducting device and material properties. This information will be of value to system designers in understanding the impact of SFCLs on network protection systems during faults and in planning the relative positions of multiple SFCLs.

Enhanced Protection Scheme for Smart Grids Using Power Line Communications Techniques—Part II: Location of High Impedance Fault Position

Abstract: An effective protection scheme against high impedance faults (HIFs) has to efficiently confront the issues of detection and location simultaneously. In Part I of this study the issue of detection is investigated, while in Part II a method that deals with the exact location of HIF position using an installed power line communication (PLC) system is elaborated. This method comprises specific test signal injections into the power grid after a HIF alarm is set. Using impulse responses that are recorded by the PLC devices, the location of the fault may be derived. A flowchart that describes the usage of the complete method for HIF detection and location is presented. The impulse responses that correspond to several fault cases are shown and the methodology that may lead to the fault location is explained. The effect of the fault type and its impedance on the efficacy of the method is highlighted. Finally, the model is applied to a line that is part of the Greek rural distribution system and its validity is tested.

Enhanced Protection Scheme for Smart Grids Using Power Line Communications Techniques—Part I: Detection of High Impedance Fault Occurrence

Abstract: Occurrence of high impedance faults (HIFs) in rural overhead power distribution networks may cause safety and economic issues for both public and the utility. Such faults may not be detected by the conventional protection schemes, so the development of a more sophisticated method is necessary. The forthcoming evolution of power networks to smart grids creates opportunities for new technologies to be implemented to that purpose. Utilities may transmit data that are necessary for the system operation using specific frequency ranges. A novel method utilizing these is proposed in this work. The monitoring of the network's input impedance in these frequency ranges can be used for detection of HIF occurrence, because such faults impose significant changes in its value. The proposed method is applied to single branch topologies, as well as to an existing topology of a Greek rural distribution system. Significant conclusions are derived in both cases. Moreover, the influence of several parameters, such as fault impedance and location and earth's electromagnetic properties on the method's efficacy is examined. Also, it is shown that the implementation of the proposed method may be drastically simplified by focusing on the monitoring of specific frequencies rather than the entire frequency range under study.

Over-Current Relay Model Implementation for Real Time Simulation & Hardware-In-the- Loop

Abstract: Digital microprocessor based relays are currently being utilized for safe, reliable and efficient operation of power systems. The overcurrent protection relay is the most exten­ sively used component to safeguard power systems from the detrimental effects of faults. Wrong settings in overcurrent relay parameters can lead to false tripping or even bypassing fault conditions which can lead to a Therefore it is important to validate the settings of power protection equipment and to confirm its performance when subject to different fault conditions. This paper presents the modeling of an overcurrent relay in SimPowerSystems (MATLAB/Simulink ). The overcurrent relay has the features of instantaneous, time definite and inverse definite minimum time (IDMT) characteristics. A power system is modeled in SimPowerSystems and this overcurrent relay model is incorporated in the test case. The overall model is then simulated in real-time using Opal-RT's eMEGAsim real-time simulator to analyze the relay's performance when subjected to faults and with different characteristic settings in the relay model. Finally Hardware-in-the- Loop validation of the model is done by using the overcurrent protection feature in Schweitzer Engineering Laboratories Relay SEL-487E. The event reports generated by the SEL relays during Hardware-in­ the-Loop testing are compared with the results obtained from the standalone testing and software model to validate the model. algorithms for adaptive protection, designing system integrity protection schemes (SIPS), remedial action schemes (RAS) and other applications (2). In this paper, a detailed model for overcurrent relays is provided. To assess the performance of this model a test system is designed in SPS and is simulated in RT using Opal­ RT's eMEGAsim real-time simulator. Once the SIL model is certified, it is further validated by HIL simulation using the overcurrent protection function of Schweitzer Engineering Laboratories (SEL) relay SEL-487E. The results obtained by the SIT.., and the HIL are compared. SPS does not have a dedicated library for protection functions. Therefore it is necessary to validate the model with HIL so that the validated software model can be used for accurate representation of power system protection components. Similar approach for protection relay model validation has been demonstrated in (3) ( 4) using different modeling platform and RTS. The remainder of the paper is arranged as follows. Section II offers a literature review on overcurrent relays. Section III presents the details of the overcurrent relay modelled in SPS. Section IV focuses on the design of test system in SPS and incorporation of proposed relay model in the test case. SIL simulation and results are discussed in Section V, while standalone testing and HIL validation is explained in Section VI. Finally in Section VII , conclusions are drawn and future work is outlined.

Reliability Study of HV Substations Equipped With the Fault Current Limiter

Abstract: Of particular interest to restrict the short-circuit level of interconnected power systems is to exploit fault current limiter (FCL) technologies. FCLs let the system planners devise new reliable and rather economical substation configurations and provide the possibility of proposing a promising cost-effective and prompt solution to the fault current over duty problem in the existing substations. This paper attempts to assess reliability of substation architectures accommodating the FCL operation and, besides, numerically investigates the FCL's impacts on the substation reliability indices. In order to clarify the proposed approach, two case studies with and without FCL are analyzed and compared. Although the discussions raised here are applicable for reliability modeling of all structures, five common substation configurations, namely: (1) single-bus single-breaker; (2) double-bus single-breaker; (3) ring bus; (4) one breaker and a half; and (5) double-bus double-breaker are considered in this paper. Numerical studies reveal that FCL deployment, while keeping the maximal flexibility of substation, may deteriorate the reliability indices of the substation due to the possible failures of FCLs.

Applying self-healing schemes to modern power distribution systems

Abstract: Self-healing schemes in the context of power distribution systems have the objective of performing fault location, isolation, and service restoration in an automated fashion, i.e., without (or with limited) distribution system operator and repair crew intervention. Some of the intrinsic benefits of this smart distribution technology are increased reliability due to outage duration reduction, more efficient use of personnel and resources (crews, operators, vehicles, etc), and increased operational flexibility. Reliability is naturally increased since less time is needed for locating and isolating faulted feeder areas, as well as for restoring customers located on healthy feeder sections. Self-healing schemes are an inherent part of the Smart Grid and are expected to play a fundamental role in modern and future distribution systems. It is worth noting that the switchgear technology (protective and switching devices, including adaptive protection), sensors, enterprise systems and communications infrastructures required for the implementation of self-healing schemes represent the basis for the execution of other smart distribution applications such as automated system reconfiguration and optimization. Therefore, a growing number of self-healing projects are being implemented by utilities as part of their power delivery modernization plans. This paper discusses the estimation of reliability benefits of self-healing schemes, with emphasis on Fault Location, Identification and Service Restoration (FLISR) applied to real distribution feeders.

A Hybrid Method for Power System Frequency Estimation

Abstract: Power system frequency is a critical parameter of voltage and current measurements for many applications, such as power quality, monitoring, and protection. This paper presents a hybrid approach for frequency estimation based on Taylor series expansion and Fourier algorithm. The method is derived using a dynamic signal model with varying parameters. The changing envelope of a power signal within an observation data window is approximated with a second-order Taylor series. A Fourier algorithm-based method is proposed to compute the parameters of such signal model. The algorithm using the linear model approach aimed at alleviating the computational complexity is also presented. The comparison of the performance under various conditions between the two approaches is conducted. Inheriting from the use of Fourier algorithm, this hybrid algorithm is immune to power system harmonics. It achieves excellent performance for signals with dynamic variations. The performance is investigated and compared with other techniques through simulations for various scenarios observed in real power systems. Experimental studies demonstrate the advantages of the proposed algorithm.

Cyber security impacts on all-PMU state estimator - a case study on co-simulation platform GECO

Abstract: Traditional state estimators require longer scan time, leading to delayed, and inaccurate state estimation Given the increased deployment trend of phasor measurement units (PMUs), it is expected that all-PMU state estimation will eventually replace traditional or mixed state estimators at the control centers of power utilities Due to the repeated calibration of the voltage and current transformers at the measurement sites, and direct time-synchronized measurement of phasors, the estimated state by an all-PMU state estimator is not only accurate, but also available at a rapid rate, leading to the use of the system state for protection, stabilization, and even calibration of the measuring devices However, due to high reliance on an advanced communication network infrastructure for the delivery of large amount of measurements in real-time, the cyber attack surface of the power system is increased Deliberate cyber attacks or unintentional network failures can affect the state estimator leading to misoperations of the power system In this paper, we study the cyber security impacts on the all-PMU state estimator, using a power system and data network co-simulation method A linear state estimator for a model of the New England 39-bus system and the corresponding data network is built in a global event-driven co-simulation platform “GECO” which was developed and leveraged for our experimental setup The co-simulation of PSLF (power system simulator) and NS-2 (network simulator) is run with injection of attacks on the network The injected cyber attacks in the form of network failures or malicious data injection are simulated and their effects are observed We also, observe the robustness of the all-PMU state estimator, when the number of affected measurements is below a threshold

Over-current relay model implementation for real time simulation & Hardware-in-the-Loop (HIL) validation

Abstract: Digital microprocessor based relays are currently being utilized for safe, reliable and efficient operation of power systems. The overcurrent protection relay is the most extensively used component to safeguard power systems from the detrimental effects of faults. Wrong settings in overcurrent relay parameters can lead to false tripping or even bypassing fault conditions which can lead to a catastrophe. Therefore it is important to validate the settings of power protection equipment and to confirm its performance when subject to different fault conditions. This paper presents the modeling of an overcurrent relay in SimPowerSystems (MATLAB/Simulink). The overcurrent relay has the features of instantaneous, time definite and inverse definite minimum time (IDMT) characteristics. A power system is modeled in SimPowerSystems and this overcurrent relay model is incorporated in the test case. The overall model is then simulated in real-time using Opal-RT's eMEGAsim real-time simulator to analyze the relay's performance when subjected to faults and with different characteristic settings in the relay model. Finally Hardware-in-the-Loop validation of the model is done by using the overcurrent protection feature in Schweitzer Engineering Laboratories Relay SEL-487E. The event reports generated by the SEL relays during Hardware-in-the-Loop testing are compared with the results obtained from the standalone testing and software model to validate the model.

Analysis and solutions of overcurrent protection issues in a microgrid

Abstract: Implementation of microgrid concept creates several issues to the existing protection scheme in the radial distribution network. Contribution of short-circuit current from the main grid and distributed generations result in variations of fault current levels inside the microgrid depending on the location and capacity of the distributed generators. The changes cause detrimental effect of sympathetic tripping, blinding of protection, relay over-reaching, relay under-reaching and loss of selectivity of the overcurrent protection scheme. Such issues must be managed carefully to ensure full benefit from microgrid adaptation. Analysis of the existing overcurrent protection schemes applied in a microgrid with distributed generations reveal the incapability of the system to adapt to the new challenges. Some solutions that could rationalize the protection challenges are also presented in this paper.

A study on interdependencies of cyber-power networks in smart grid applications

Abstract: A cyber-power system, a type of cyber-physical system, contains two interconnected infrastructures: a power network and a cyber network. The cyber network monitors, protects and controls the power network. Without the cyber network, the power network cannot operate efficiently or reliably. This paper studies the cyber-power interdependencies in smart grids and categorizes four types of interdependencies between cyber and power networks. The proposed classification permits the assessment of adverse effects of cyber network failures on the power network's operation. Two applications of cyber-power systems, automated substations and micro grids, are discussed in this paper, and certain cyber-power interdependencies are listed as examples.

State of the art of Fault Current Limiters and their applications in smart grid

Abstract: We summarize the state of the art of Fault Current Limiters (FCL), focusing on devices in or near to field test status, and then, based on capabilities and characteristics of FCLs and smart grid, assign the various types to the most appropriate nodes in a smart grid.: 1) solid-state FCLs can be installed at microgrid and renewable energy resource feeders to replace circuit breaker and maintain protection coordination of the transmission network; 2) resistive superconducting FCL, saturated iron-core superconducting FCL and dynamic FCL can be installed at distribution substations to maintain downstream over-current protection without current harmonics disturbance; and 3) resistive and saturated iron-core superconducting FCLs can be installed at optimum locations in the transmission network to reduce fault currents to within a tolerable range when a new power plant is installed. With these placements, we can make full use of the advantages of smart grid's communication network and different characteristics of FCL devices in different categories to offer a more flexible and reliable protection for future power grid.

Analysis of Microgrid protection strategies

Abstract: Microgids have been proposed to improve reliability and stability of electrical system and to ensure power quality of modern grid. In this paper, different protection strategies are investigated for adaptive safety protection. It is essential to protect a Microgrid in both the grid-connected and the islanded mode of operation against all different types of faults. This paper describes Microgrid protection and safety concept with central control and monitoring unit where multifunctional intelligent digital relay could be used. This central control & monitoring infrastructure is used for adaptive relay settings strategy for Microgrid protection. Also FPGA based decision making is proposed for Microgrid protection to shortening response time and ensure adaptive protection.

Electromagnetic Transients in Transformer and Rotating Machine Windings

Abstract: Electromagnetic transient phenomena in transformers and rotating machines are complicated by their winding structures, with transient phenomena caused by either external events such as lightning, or by internal events such as switching operations and faults. Electromagnetic Transients in Transformer and Rotating Machine Windings explores relevant theoretical frameworks, the latest empirical research findings, and industry-approved techniques in this area. Written for professionals who want to improve their understanding of the electromagnetic transient phenomena in transformer and rotating machines windings, this research volume is also useful for university research students in power system protection, insulation condition monitoring, and incipient fault diagnosis.

Enhanced protection against false data injection by dynamically changing information structure of microgrids

Abstract: For a power grid, false data injection attacks attempt to exploit the configuration and information structure of the power system, introduce erroneous but conforming values into certain state variables, and evade the existing detection techniques based on residual testing, leading to severe security threat to the overall system. Accordingly, an enhanced method of evading false data injection in power grids is proposed. Since the power system can typically be partitioned into a group of microgrids the proposed approach shows that the microgrids (i.e., their boundaries and information sharing structures) are dynamically reconfigured, which makes it impossible to organize a synchronized data injection that exploits a fixed configuration and coordinately attacks certain meters in the configuration. Examples are used to demonstrate the effectiveness of the proposed scheme.

Line outage detection using support Vector Machine (SVM) based on the Phasor Measurement Units (PMUs) technology

Abstract: Phasor Measurement Units (PMUs) have been increasingly widespread throughout the power network. As a result, several researches have been made to locate the PMUs for complete system observability. Many protection applications are based upon the PMUs locations. This paper introduces an important application in power system protection which is the detection of single line outage. In addition, a detection of the outaged line is achieved depending on the variations of phase angles measured at the system buses where the PMUs are located. Hence, a protection scheme from unexpected overloading in the network that may lead to system collapse can be achieved. Such detections are based upon an artificial intelligence technique which is the support Vector Machine (SVM) classification tool. To demonstrate the effectiveness of the proposed approach, the algorithm is tested using offline simulation for the 14-bus IEEE system.