Search

Power system simulation is an important means to study the dynamic behavior, to ensure the safety and stability, and to optimize the operation of a power grid. Pure physical simulation and digital simulation have their own advantages and disadvantages. A three-phase four-wire hybrid simulation platform integrating the advantages of both the digital simulation and physical simulation is developed by combining the physical simulation system and real-time digital simulator. The platform is rated at 400 V and 50 kVA with the short-circuit capacity of 500 kVA and can supply ten times the rated current to support the simulation of various short-circuit faults. An improved interface algorithm based on an ideal transformer model is proposed to extend the stability region of a hybrid simulation. Hybrid simulation experiments are conducted under two cases, and the comparison with the digital simulation demonstrates the performance of this platform and the potential applied to a modern power system. This platform has been equipped in a key laboratory of smart power grid technology. [ABSTRACT FROM PUBLISHER]

Recently, Andreotti et al. (2015) have presented a new tool for lightning induced voltage calculations on power networks. This tool, named Circuit for Lightning Induced Voltage (CiLIV), has been initially developed for straight and vertical lightning channels; afterwards, the tool has been extended to evaluate induced voltages produced by tortuous lightning channels. However, in the aforementioned studies, only simple power network configurations have been examined. Therefore, aim of this paper is twofold: 1) to apply CiLIV to more complex network configurations, that is, complex networks equipped with transformers, surge arresters, groundings, and so on; 2) to investigate the effects of channel tortuosity on the voltages induced in these complex networks. [ABSTRACT FROM PUBLISHER]

The article presents a Dispatcher Training Simulator (DTS) based on the Hybrid Real-Time Power System Simulator (HRTSim). The main DTS advantage is the real-time circuit-mode states control of the electric power systems (EPS) equipment, including isolated-phase control. This DTS operates in all EPS modes: normal, emergency, and postemergency. It is achieved by hybrid simulation, which includes digital, analogue and physical modelling approaches. The dispatcher training simulator requires expert software, structure of which is described in this article. In additional, implementation of this DTS for Tyumen EPS, Russia was demonstrated. Finally, the implementation results are given to demonstrate the efficiency of the DTS application for the dispatchers' skills upgrading. [ABSTRACT FROM AUTHOR]

Estimation of power system parameter plays an important role in the modern power system. In this paper, estimation of harmonics components in a power system synthetic signal is done by an improved estimation technique called as ADALINE. This neural estimator basically uses an adaptive interpreted linear neuron. Learning parameter is adjusted to keep the difference between the Real and Expected values to satisfy the difference that arises due to error equation. Tracking of the fourier co-efficent of the proposed signal, which also constitutes a noise, and DC decaying component can be done easily and accurately using the proposed algorithm. To verify the effectiveness of the proposed algorithm, estimation of amplitude as well as Phase of fundamental and harmonics is carried out. The simulation results obtained are encouraging to work more on the estimation of signals. [ABSTRACT FROM AUTHOR]

SUMMARY In a distribution line, power system control and power equipment investment are planned based on a measured power system current. However, recently the mass introduction of photovoltaic (PV) make it difficult for us to precisely measure the demand curve that is a current consumed by electrical equipment because the reversal power flow from PV systems is superposed. Therefore, the prediction of demand curves of distribution line is indispensable for power system management. In addition, it is also necessary to estimate the reliability of the predicted values as well as predicted current itself. In this paper, we propose the estimation method of the prediction interval that is the index of reliability based on the past demand curve database. The feature of the proposed method based on Just-In-Time (JIT) modeling make it possible for us to accurately estimate the prediction interval by the normalized database of demand curve. In this paper, some numerical examples are presented, which demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Nowadays, the simulation tools used to perform power system analysis are evolving into the many-core computation era; some of these techniques propose to tear the power system network into several subnetworks (islands) for its parallel processing. The island's detection is an issue considered by the power flow analysis due to management activities such as feeder reconfiguration, fault detection, and isolation, among others, that generate topological changes. These methods include graph theory, checking the circuit breaker status and on-site measurements, decision trees, frequency deviation, and pattern recognition, among other techniques, which are focused to detect topology changes that may generate islands and affect the state estimation of the system. In contrast, other techniques such as the approximate minimum degree perform a reorganization of the $Y_{{\text{BUS}}}$ matrix that describes the network components and their connectivity, looking to factorizing the $Y_{{\text{Bus}}}$ matrix to solve the power flow problem. These techniques are very functional and efficient; however, some of them require detailed information of the network, and are addressed to cover meshed and radial network configurations separately. This paper presents an iterative algorithm that uses the compressed coordinate branch-to-node matrix for detecting, classifying, and grouping islands within sparse matrixes, describing mesh or radial networks. This algorithm is a valuable tool to simplify islands location and can be implemented using any programing language due to its simplicity. This method is used in Distribution System Simulator - Real Time Version (DSSim-RT), which is a simulator based in OpenDSS, for tearing the power system network to allow the multithread power flow analysis of distribution systems in real time. [ABSTRACT FROM PUBLISHER]

Global complete chaos synchronization in impulsive power systems with delay is studied. The sufficient conditions of exponential synchronization are established based on the theory of stability of impulsive differential equations with delay. Illustrative examples that demonstrate the applicability and effectiveness of the obtained results are given. [ABSTRACT FROM AUTHOR]

Many power systems applications such as power flow and short-circuit analysis require very large sparse matrix computations. With the increase in reliance on our electric infrastructure, power systems are continually growing in size, creating greater computational complexity in solving these large linear systems within reasonable time. For sparse matrix applications, it is desirable to have an algorithm with low runtime complexity in terms of the number of nonzeros in the matrix. There have been several recent advances in computational methods in other fields that, if applied to power system, could make real-time dynamic simulation a reality. Much work has been done for specific types of these problems where the system is symmetric and diagonally dominant, similar to the form of power system matrices. This paper details an expansion on the current work in fast linear solvers to develop power system specific methods that show potential for accurate solutions in $O(m \log ^2 n)$ run times, where $n$ represents the number of nodes and $m$ represents the number of nonzeros in the power system matrix. This paper presents the simulation validation of a recently developed recursively solved iterative chain method for sparse matrices using a low stretch spanning tree preconditioner. [ABSTRACT FROM PUBLISHER]

For a reliable and stable operation of a power system network, it is important to monitor the dynamics of the system. For this purpose, in real system phasor measurement units (PMUs) have been installed to give information about the grid conditions. Due to a large interconnected non-linear system, there is a possibility of system collapse due to unusual high stress. Hence, it is essential to detect the generators going out of step at an early stage and separate them. This study presents two algorithms: first one in meant to identify the coherency between the generators in real-time signal and second algorithm functions to quickly determine the critical generators. The algorithm for coherency identification between the generators uses time--frequency coherency based on smoothed pseudo-Wigner--Ville distribution signal processing technique. The proposed scheme is validated on several PMUs signals. Further, the Lagrangian method is applied to detect the critical sets of generators going out of step following the severe fault occurrence in the line. This is based on the calculation of energy. The suggested approach discussed in this study can be applied to dynamically reduce a large power system. [ABSTRACT FROM AUTHOR]

The framework for virtual integration of laboratories enables co-simulation and joint experiments that include hardware and software resources hosted at geographically distributed laboratories. The underlying concept of such framework is geographically distributed real-time (RT) co-simulation. To this end, digital RT simulators are interfaced over long distances via shared communication network such as the Internet. This study proposes an architecture for a modular framework supporting virtual integration of laboratories that enable flexible integration of digital RT simulators across Europe. In addition, the framework includes an interface that enables access for third parties via a web browser. A co-simulation interface algorithm adopted in this study is based on representation of interface quantities in form of dynamic phasors. Time delay between RT digital simulators is compensated by means of phase shift that enables simulation fidelity for slow transients. The proposed architecture is realised for the integration of laboratories across Europe that are located at RWTH Aachen University in Germany, Politecnico di Torino in Italy and at European Commission Joint Research Centres in Petten, Netherland and in Ispra, Italy. The framework for virtual integration of laboratories presented in this study is applied for co-simulation of transmission and distribution systems. [ABSTRACT FROM AUTHOR]

System frequency may change from defined values while transmitting power from one area to another in an interconnected power system due to various reasons such as load changes and faults. This frequency change causes a frequency error in the system. However, the system frequency should always be maintained close to the nominal value even in the presence of model uncertainties and physical constraints. This paper proposes an Active Disturbance Rejection Controller (ADRC)-based load frequency control (LFC) of an interconnected power system. The controller incorporates effects of generator inertia and generator electrical proximity to the point of disturbances. The proposed controller reduces the magnitude error of the area control error (ACE) of an interconnected power system compared to the standard controller. The simulation results verify the effectiveness of proposed ADRC in the application of LFC of an interconnected power system. [ABSTRACT FROM AUTHOR]

Graphical user interfaces have been progressively used in the classrooms to provide users of computer simulations with a friendly and visual approach to specify all input parameters with enhanced configuration flexibility. In this paper, an educational software package called PowSysGUI (Power System GUI), which runs on MATLAB and uses graphical user interfaces, has been developed for analysis and simulation of small to large size electric power systems. PowSysGUI is open-source software and anyone can see the inner structure of the program to figure out how to code a power engineering problem. It is designed as a simulation tool for researchers and educators, as it is simple to use and modify. PowSysGUI has algorithms for solving power flow, small signal stability analysis, and time-domain simulation. In the case studies, IEEE 16-machine 68-bus test system is given to show the features of the developed software tool. Moreover, classroom experience has shown that the developed software package helps in consolidating a better understanding of power system stability phenomena. [ABSTRACT FROM AUTHOR]

Future power systems with high penetrations of variable renewables will require increased levels of flexibility from generation and demand-side sources in order to maintain secure and stable operation. One potential flexibility source is large-scale energy storage, which can provide a variety of ancillary services across multiple time scales. In order for appropriate levels of investment to take place, and in order for existing assets to be utilized optimally, it is essential that market signals are present which encourage suitable levels of flexibility, either from storage or alternative sources. Suboptimal storage plant dispatch due to uncertainty and inefficient market incentives are represented as operational constraints on the storage plant, and the impact of these inefficiencies are highlighted. Thus, changes required in operational practices for storage plant at different installed wind capacity levels, and the challenges that private storage plant operators will face in generating appropriate bids in a market environment at high variable renewable penetrations are explored. The impacts on system generating costs and storage profits are explored under different plant operating assumptions. [ABSTRACT FROM PUBLISHER]

With the increasing occurrence of extreme weather events, the short circuit and line-breaking faults in transmission lines caused by line galloping have been threatening the security operation of power systems. These faults are also hard to be simulated with current simulation tools. A numerical simulation approach of power systems is presented to simulate the clustered, cascading faults of long-timescale caused by line-galloping events. A simulation framework is constructed in which large numbers of fault scenarios are simulated to reflect the randomness of line galloping. The interaction mechanism between power system operation states and line galloping processes is revealed and simulated by the solution of differences of timescales and parameters. Based on Power System Simulator/Engineering (PSS/E), an extended software package for line galloping simulation is developed with Python, which extends the functionalities of the PSS/E in power system simulation. An example is given to demonstrate the feasibility of the proposed simulation method. [ABSTRACT FROM AUTHOR]

With the emerging growth of high-voltage direct current (HVDC) transmission in modern power systems, the HVDC grid has become a hot topic in recent academic research and real projects. In the DC grid, DC faults can have very serious consequences, and so the faulty DC parts need to be rapidly isolated from the system. Compared to the full-bridge converters for the DC grid, DC circuit breakers are preferred to deal with this problem economically. In this paper, the self-excited resonant DC circuit breaker is reviewed. Then, a novel scheme of hybrid DC circuit breaker is introduced, and the operation principle of the proposed circuit breaker is described in detail. Finally, a four-terminal HVDC grid based on a modular multilevel converter (MMC) is used as the DC test system in PSCAD/EMTDC to verify the validity of the proposed DC circuit breaker. From the simulation results, it is seen that the proposed DC circuit breaker has advantages on current interruption time, voltage on DC circuit breaker, investment, etc. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

The motivation and training of a proficient and diverse pool of power engineers, system operators, and policymakers is an important challenge for the electric industry. Power system experts are increasingly in demand globally to facilitate transitions to more environmentally friendly energy systems. More generally, citizens with a basic understanding of load balancing and renewable energy sources are more effective partners in increasingly complex power economies and political decisions. To address the need for an accessible general introduction to power systems, we are developing Griddle, an educational video game that introduces secondary school students to the basics of power system design, scheduling, and operation. We describe the design of Griddle's gameplay and underlying simulation, improvements made in response to user feedback, alignment with emerging teaching standards, and a high school classroom evaluation (n = 178) of Griddle's significant transformative impact, with the goal of validating the game-based learning approach and sharing “lessons learned” with designers of related tools. We find that Griddle is effective at engaging students and presents evidence that it helps students integrate key concepts, and we identify areas where further development and study are needed. [ABSTRACT FROM AUTHOR]

Power systems require a certain amount of flexibility to meet varying demand and to be able to cope with unexpected events, and this requirement is expected to increase with the emergence of variable power generation. In this paper, we focus on gas engine power plant technology and the beneficial influence its flexible operation can have on a power system. The study introduces the concept of a combined-cycle gas engine power plant (CCGE), which comprises a combination of several gas-fired combustion engines and a steam turbine. The operation of CCGE is then comprehensively analyzed in electricity and reserve production in the South African power system and compared with combined-cycle gas turbine (CCGT) technology. Even though CCGE is a form of technology that has already been commercialized, it is rarely considered as a source of flexibility in the academic research. That is the notion providing the motivation for this study. Our core contribution is to show that the flexibility of CCGE can be valuable in power systems. The methodology is based on the unit-level model of the studied system and the solving of a day-ahead unit commitment problem for each day of the simulated 11-year period. The simulation studies reveal how a CCGE is able to offer system flexibility to follow hourly load variations and capacity to provide reserve power effectively. [ABSTRACT FROM AUTHOR]

In this paper, we present a scalable approach for real-time simulation of ship power systems with high-frequency power electronics converters (100–200 kHz). The proposed approach is based on the latency-based linear multistep compound method and relies on field-programmable gate array (FPGA) execution. Several examples of increasing dimension and complexity are used to evaluate the scalability—both of in terms of computational delay and of resources usage—of the proposed approach. Real-time execution with a 50 ns time step is achieved for all the examples considered. [ABSTRACT FROM PUBLISHER]

Electromagnetic transient (EMT) simulation of nonlinear elements in power systems is a particular challenge due to the requirements of an accurate representation and an efficient solution. The existing real-time simulators utilize a piecewise linear representation along with a fixed time step for the solution of nonlinear elements. This paper proposes the detailed methodologies for applying variable time stepping to real-time EMT simulation to improve the simulation accuracy and efficiency. The challenges, the feasible solutions, and corresponding restrictions of applying various variable time-stepping schemes along with nonlinear element solution methods in real time are discussed. The offline simulation and the real-time hardware emulation of two case studies, a full-bridge diode circuit and a power transmission system, are presented. The case studies were implemented on the field-programmable gate array device (Xilinx Virtex-7 XC7VX485T) in real time using high-level synthesis tool to achieve a parallelized and pipelined hardware design with minimum coding effort. The real-time emulation results captured by an oscilloscope are validated against the offline simulation on Saber and PSCAD/EMTDC software tools. [ABSTRACT FROM PUBLISHER]

This paper explores the performance of dynamic neural networks (DNNs) in solving the combined economic-emission dispatch (CEED) problem. The idea behind the CEED formulation is to estimate the optimal generating unit schedule in such a manner that both the fuel cost and the pollutant emission levels are minimized for a given load demand. DNNs present an elegant approach to transform the CEED optimization problem into dynamical systems whose states converge to the desired optimal generated power configuration. As compared to other neural network approaches, e.g., multilayer perceptron or radial basis function networks, complicated problem mapping or training is not necessary in DNN. Further, the convergence characteristics of DNNs are theoretically well established. Three DNN structures, namely, gradient based primal DNN, Lagrangian based primaldual DNN, and dual DNN, are investigated in optimizing the CEED of 6 and 11 u test power systems. Compared to other optimization techniques, the investigated DNNs feature a transparent design procedure, lower model complexity, and faster convergence. [ABSTRACT FROM AUTHOR]

Inrush current simulation plays an important role in many tasks of the power system, such as power transformer protection. However, the accuracy of the inrush current simulation can hardly be ensured. In this paper, a Jiles-Atherton (J-A) theory based model is proposed to simulate the inrush current of power transformers. The characteristics of the inrush current curve are analyzed and results show that the entire inrush current curve can be well featured by the crest value of the first two cycles. With comprehensive consideration of both of the features of the inrush current curve and the J-A parameters, an automatic J-A parameter estimation algorithm is proposed. The proposed algorithm can obtain more reasonable J-A parameters, which improve the accuracy of simulation. Experimental results have verified the efficiency of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Scheduling for generation units in modern power markets is one of the most important tasks of independent system operators (ISO). To ensure secure and economical operation of power systems, ISOs solve the security constrained unit commitment (SCUC) problem. SCUC is a very complex and large-scale optimization problem. In addition, uncertainties imposed by wind generators and variable loads add to this complexity. Stochastic SCUC, one of the most important problems for scheduling generation units, considers different power system uncertainties. A considerable amount of previous works demonstrates the efficacy of decomposition techniques, such as benders' decomposition for Stochastic SCUC. Solving this problem, even with decomposition techniques, for large-scale systems with multiple uncertainties is very time-consuming. A major part of Stochastic SCUC constraints belongs to network security. This paper presents a method in which cumulants are used to detect and eliminate inactive network constraints during the solving process. As a result, the method reduces the number of network security constraints and decreases the simulation time considerably. Implementing the proposed method on a six -bus test system and a modified IEEE 118-bus system demonstrates its efficiency and accuracy. [ABSTRACT FROM AUTHOR]

This paper presents a novel frequency-domain approach for distributed harmonic analysis (DHA) of a multi-area interconnected electric power system within restructured environment. The proposed approach is based on a decentralized structure in which harmonic analysis of an area is independently conducted, even with limited available data, via local computing resources. The large-change sensitivity (LCS) concept is then applied in a secure platform to account for the effects of whole network to each single area of the interconnected power system. Frequency-dependent models of system elements accompanied by any existent harmonic assessment method can be utilized for harmonic penetration calculation. The proposed DHA approach is capable of finding exact values as those of the interconnected system using TCP/IP communication facility. Moreover, it allows operator of a utility to independently conduct DHA within a restructured power network. The developed method is implemented in an existing software package and applied to several networks including the IEEE 118-bus test system. [ABSTRACT FROM AUTHOR]

Special protection schemes (SPSs) are an efficient alternative to increase the flexibility in the operation of power systems. The implementation of SPSs is often motivated by technical rather than economic reasons. The aim of this paper is to propose a novel framework for the analysis and development of SPSs in a context from the Chilean experience that comprises both technical and economic incentives to enable high penetration of solar energy. With this purpose, this paper explores the new capabilities of SPSs based on maximizing the cost-effective integration of solar power into a power system, given a set of technical challenges (congestion and dynamic response in case of contingencies) that must be considered in their design. In this framework, three main drivers were identified and discussed. The discussion includes the mechanisms associated with each driver that promote the massive integration of solar power. Moreover, within the proposed technical-economic framework, a methodology for driver selection and SPS design is proposed. The methodology and the drivers identified are evaluated in the Chilean power system. [ABSTRACT FROM AUTHOR]

Real-time (RT) simulator is a powerful tool for analyzing operational and control algorithms in electric power systems engineering. For understanding the dynamic and transient behavior of a power systems, significant RT computation capabilities are essential. A single unit of RT simulator has limited simulation capabilities. The most common way of augmenting simulation capability is using a bank of locally connected RT simulators. However, creating a large-sized bank of RT simulators involves significant financial investments and hence may not be feasible at all research facilities. Power and energy systems research facilities that use RT simulators are at diverse physical locations. In addition to RT simulators, research facilities around the world house an array of facilities with unique power, energy, and control systems for innovative research. To leverage these unique research facilities, geographically distributed RT simulation based on Wide Area Network (WAN) is required. Typical RT simulators perform simulations with time-steps in the order of milliseconds to microseconds, whereas data latency for communication on WAN may be as high as a few hundred milliseconds. Such communication latency between RT simulators may lead to inaccuracies and instabilities in geographically distributed RT simulations. In this paper, the effect of communication latency on geographically distributed RT simulation is discussed and analyzed. In order to reduce the effect of the communication latency, a Real-Time Predictor (RTP), based on linear curve fitting is developed and integrated into the distributed RT simulation environment. Two geographically distributed digital RT simulators are used to perform dynamic simulations of an electric power system with a fixed communication latency and the predictor. Empirical results demonstrate the effects of communication latency on the simulation and the performance of the RTP to improve the accuracy of simulations. [ABSTRACT FROM AUTHOR]

This paper proposes a new approach for power system transient stability simulation, which is based on a semi-analytical solution (SAS) of power system differential-algebraic equations. In this paper, an SAS is derived using the Adomian decomposition method as a closed-form explicit function of symbolic variables such as time, the initial state, and other variables on system conditions and; hence, it can directly give a power system's dynamic trajectory being accurate for a certain time window. Unlike a traditional numerical integration based simulation approach, the proposed new approach offline derives an SAS and online evaluates the SAS by plugging in values of symbolic variables for a series of time windows making up the desired simulation period. This paper further studies the maximum length of the time window for an SAS being accurate and proposes a divergence indicator for simulation using adaptive time windows. Implementation of this new approach on parallel computers is also studied. The new approach is validated through contingency simulation of the IEEE 10-generator 39-bus system with detailed generator models. [ABSTRACT FROM AUTHOR]

Real-time operation of electric power systems under high penetration of renewable energy generation has to incorporate strategies for managing the uncertainty associated with this type of power sources. In the case of the unit commitment problem, models based on robust optimization have been widely used for the day-ahead computation of power dispatch and reserves schedule. Typical approaches use uncertainty sets with fixed levels of conservativeness, without considering the real-time performance of the solutions. This paper proposes a solution scheme for the adaptive robust unit commitment problem using online adjusted data-driven uncertainty sets. Conservativeness parameters of the uncertainty sets are dynamically calculated as a function of previous operating results and incoming data via reinforcement learning, resulting in an online learning-optimization framework. The paper also develops an experimental framework to simulate real-time operation under the proposed methodology. Out-of-sample experiments illustrate the effectiveness of the proposed scheme against well-known benchmarks with fixed robustness levels. Results show improvements in power generation costs, voltage violations, and use of reserves. Two systems of different sizes are analyzed, illustrating the scalability of the proposed approach. • Q-learning algorithms for data-driven robust uncertainty sets adaptation. • Uncertainty sets dynamical adaptation based on real-time system indicators. • Novel framework for real-time power systems operation simulation. • Results comparison against two-stage robust and stochastic optimization approaches. • Statistically significant lower generation costs and use of system reserves. [ABSTRACT FROM AUTHOR]

This paper presents an improvement in the long-term hydrothermal system operation planning by including peak generation as a decision variable in the simulations, in order to better operate the hydro plants. Although this has been widely considered in the short-term, the objective is to correctly set the power system operation planning to avoid instantaneous shortages and blackouts. Thus, the instantaneous generation capacity is included in the objective function in order to better consider this variable in long-term operation planning. The results show that it is possible to significantly increase peak power by simply modifying the operation of hydro plants. Moreover, this approach does not present a significant increase in the operation costs. [ABSTRACT FROM AUTHOR]

This paper illustrates the construction of a new class of iterative solvers for power flow calculations based on the method of Alternating Search Directions. This method is fit to the particular algebraic structure of the power flow problem resulting from the combination of a globally linear set of equations and nonlinear local relations imposed by power conversion devices, such as loads and generators. The choice of the search directions is shown to be crucial for improving the overall robustness of the solver. A noteworthy advantage is that constant search directions yield stationary methods that, in contrast with Newton or Quasi-Newton methods, do not require the evaluation of the Jacobian matrix. Such directions can be elected to enforce the convergence to the high voltage operative solution. The method is explained through an intuitive example illustrating how the proposed generalized formulation is able to include other nonlinear solvers that are classically used for power flow analysis, thus offering a unified view on the topic. Numerical experiments are performed on publicly available benchmarks for large distribution and transmission systems. [ABSTRACT FROM AUTHOR]

This article presents a study on short-circuit current limiting using resistive superconducting fault current limiters, based on a melt cast processed BSCCO-2212. The application of the resistive superconducting fault current limiter was analyzed when installed downstream of a substation, protecting a distribution feeder. The studied power system is based on a dynamic model of the IEEE 13-node test feeder considering a power system expansion scenario, including renewable power generation. As a result of the power system expansion, fault current levels tend to increase, and the resistive superconducting fault current limiter device is used for fault current mitigation. The main contribution of this article is the performance assessment of superconducting fault current limiters and its effects on power quality due to different fault locations in the system and by accounting the complexity of the power system topology. Results obtained demonstrate that the system expansion does not significantly raise fault current levels. It also demonstrated that the resistive superconducting fault current limiter has a desirable operation zone, and unwanted power interruption may occur due to its operation outside this zone. [ABSTRACT FROM AUTHOR]

The improper operation of the third-zone distance protection has been attributed as one of the factors for power system blackouts. The third-zone protection could incorrectly operate during power-swing scenarios. This research proposes a fast and practical methodology using local measurements for blocking the third-zone distance relays during stable power swings. The proposed scheme is referred to as the BTZ scheme. The proposed method calculates the relative speed of a fictitious equivalent machine from the local relay measurements. If the relative speed goes through a zero crossing, the swing is classified as a stable power swing; whereas if the speed does not go through a zero value, then the swing is classified as an unstable power swing. The benefit of the proposed method is that it analyzes the power swings from a system stability point of view, and does not need rigorous offline simulation studies to determine the relay settings. The performance of the proposed method in this paper is compared with an industry-standard method (conventional double blinder method). As is well known, the settings of the blinder-based methods are system specific and need several simulations to arrive at the blinder values. Transient simulation studies on a three-bus system and a modified Western Coordination Council 9-bus system are used to test the performance of the proposed approach. [ABSTRACT FROM PUBLISHER]

This paper proposes a new method for measurement-based modeling of nonlinear loads in power systems. The proposed method includes a combination of a binary tree algorithm with nonlinear autoregressive with exogenous input (NARX) identification. This paper demonstrates that the new method performs well without any prior knowledge of the system structure. In contrast to other load modeling methods, which are typically aimed for particular studies or load types, the proposed method can be used with any load type and for any study. Accurate load modeling is particularly important for studies of industrial networks and grids. In the study described, a field data set was collected at a mine site from a large electrical rope shovel. This data set has been used to develop a model of the rope shovel based on the proposed binary tree—NARX algorithm. When compared to other known methods, such as wavelet and sigmoid networks, the proposed method has shown the fastest training time and the highest accuracy. Finally, the modeling results have been verified against another set of field measurements from an existing network and have shown a very good agreement. [ABSTRACT FROM PUBLISHER]

Automatic synchronizing systems are used to reconnect multiple islanded power grid sections. These systems are required to function automatically with minimal human supervision because they must dispatch multiple generators simultaneously to reduce slip and voltage difference at the interconnection point. This paper describes a smart automatic synchronizing system that can connect multiple generators in an industrial power system during islanded and utility-connected modes via six different bus-tie and utility tie breakers. The automatic synchronizing system performs matching by controlling multiple governor and exciter interfaces within the facility. Controlling slip and voltage difference across any of the six different breakers in any combination is accomplished with up to six different and simultaneous power system islands. The power system studied is a large refinery containing six generators, totaling about 260 MW of generation. The functionality, operation, and validation of this automatic synchronizing system using real-time-digital-simulator tests are discussed. [ABSTRACT FROM AUTHOR]

This paper discusses some of the main issues that are generally found in protection systems of low-voltage electrical installations and presents a methodology that can be used to analyze and upgrade the existing power system protective devices in these low-voltage distribution systems. The upgrades of existing operating systems, especially low-voltage systems, always face an economic challenge where the monetary value spent on upgrades has to be justifiable against the benefit derived. If understood clearly, the benefit of upgrades to existing protective systems is larger than just making these systems safer. A gated approach for the upgrade and proper management of such systems can help in planning for future expansions, provide reliability of equipment, and decrease the overall risk for the operation of any facility. [ABSTRACT FROM AUTHOR]

Power system electromagnetic transient (EMT) simulation has been used to study the electromagnetic behavior of power system components. It generally comprises detailed models of the study area and an equivalent circuit which represents an external part of the study area. However, a detailed description of an external system that includes transmission or distribution system models is required to study the interaction among power system components because the number of high power converter based devices in a power grid have been increasing. Since detailed models of the system components are necessary to simulate a series of events such as cascading faults the computational burden of power system simulation has increased. Therefore a more effective and practical framework has been sought to handle this computational challenge. This paper proposes a co-simulation framework including a delay compensation algorithm to compensate the time delayed signals due to network segmentation and a fast and flexible simulation environment composed of non-real time power system EMT simulation on a general purpose computer with a multi core central processing unit (CPU), which is currently very popular owing to its performance. The proposed methods are applied to an AC/DC power system model. [ABSTRACT FROM AUTHOR]

This paper describes a simple and didactic procedure which illustrates the benefits of the visual aspects of MATLAB/SIMULINK for educational purposes. The novel didactic procedure is specially developed for transient stability simulation of a multi-machine power system given with full details. Structural details of various sub-models for a multi-machine power system are provided and their implementation in SIMULINK environment is outlined. Simulation results show that the developed transient simulation model is a powerful and promising tool for transient stability studies, and very helpful to understand transient stability phenomena for students and researchers. The most salient features of the developed MATLAB/SIMULINK-based model are simplicity of use, transparency, flexibility and expandability. These special characteristics are easy to understand and can be easily modified. Hence, these features make the proposed model suitable for both educational and research purposes. In addition, classroom experience has shown that the didactic procedure helps in consolidating a better understanding of power system transient stability. [ABSTRACT FROM AUTHOR]

The small-signal stability analysis of power systems concerns the critical modes as well as the modes associated with a physical meaning, e.g., the interarea oscillation modes for weakly connected systems and the modes sensitive to a particular parameter. As the order of the power-system state matrix increases, it becomes more difficult to determine these modes. In this paper, a method is proposed to compute the interarea oscillation modes of large-scale power systems. The deviation in the active power of the transmission section is selected to identify the interarea oscillation modes. Then, the two-sided Jacobi-Davidson method combined with this selection is employed to compute these modes. Participation factors are used to separate the electromechanical oscillation modes. Numerical tests show that the proposed method is valid and efficient. [ABSTRACT FROM PUBLISHER]

The power system islanding problem aims to divide the power system into several different islands after serious disturbances occur. The objective of this problem is to minimize the total generation-load imbalance of all islands while placing the coherent generators in the same island and maintaining the connectivity of each island. Two main challenges of solving this problem are the large scale of the power system and the requirement of a short computation time. In this study, we propose a tailored tabu search algorithm to solve this problem, which employs a novel initial solution generation procedure and a neighborhood operation based on the movement of the boundary nodes. The numerical experiments on 15 test instances show that this algorithm can deal with the power systems with up to 3120 nodes within 0.7 s. Then, the comparisons with some existing islanding methods based on the IEEE 39-bus system and the IEEE 118-bus system prove the validity and accuracy of our method. Finally, time-domain simulations based on three power systems demonstrate the importance of our tabu search algorithm in minimizing the impacts of the disastrous disturbances. The computational results imply that our tabu search algorithm is very effective and efficient and satisfies the requirements of islanding power systems of various sizes. [ABSTRACT FROM AUTHOR]

The increasing use of electronic converters is making possible the development of more sustainable, efficient, and reliable electric power systems, but it is also introducing new challenges that need to be addressed. Power system stability is one of them since the converter multiscale coupling between control loops and the mutual effects of multiple converters make the traditional approaches and specialized software available not fully adequate. In this context, this paper presents a software tool called CSTEP capable of carrying out small- and large-signal stability analysis for electric power systems strongly dominated by electronic converters. By utilizing the tool description, the paper provides the reader with a systematic methodology to obtain the system dynamic representation, and with some software tools for the analysis of the large and small-signal stability. Finally, the validity and functionality of CSTEP have been tested with the implementation of three use cases: a simple ac use case to illustrate the application of the system algorithm step by step, an IEEE 5-bus use case to validate the tool with already established commercial software and a more realistic system based on a medium voltage CIGRÉ benchmark to highlight the potential applications of the tool. The results show that, unlike existing tools that simplify or neglect the electric part of the grid (filters, line impedances, etc.), CSTEP can predict power system instabilities caused by the interactions of fast control loops of electronic converters with the electric part. [ABSTRACT FROM AUTHOR]

The paper presents a complex modelling of a hydro-power plant synchronized with an electrical network. A dynamic performance model of a synchronous generator, Kaplan turbine, turbine controller, excitation system, automatic voltage regulator, transformer and simplified electrical network is designed in accordance with the IEEE recommended practices and standards. The developed model which is validated with the in situ measurements taken on the Mavčiče hydro-power plant and nearby 110 kV Slovenian electrical network shows a great matching of the characteristics. An important property of the model is its ability to simulate the various types of the power-system operation and the impact of the hydro-power plant control systems on the electrical network, especially the hazard scenarios that cannot be tested on a real power system. [ABSTRACT FROM AUTHOR]

Copyright of Tecnura is the property of Tecnura and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper studies the impact of wind generation on system costs and prices in Ireland. The importance of wind power and potential impacts on system costs is of interest to power system planners and policy makers globally. However, the impact of wind generation on system costs has been only studied with limited actual data from power systems with increased wind penetration. The paper uses a unique dataset of half-hourly system demand, generation, forecast and actual wind generation, along with Irish system marginal price (SMP) data from 2008 to autumn 2012. An econometric time-series model of SMP as a function of forecast and realized demand and wind generation yields results which suggest that each 1% increase in wind generation reduces SMP in Ireland by about 0.06%, while each 1% wind forecast error increases SMP about 0.02%. In absolute terms, though, at the mean the impact of wind forecast errors is small, or about 0.4€cent/MWh-wind generated. [ABSTRACT FROM AUTHOR]

As the application of wind power energy is rapidly developing, it is very important to analyze the effects of wind power fluctuation on power system operation. In this paper, a model of thermal unit commitment problem with wind power integration is established and chance constrained programming is applied to simulate the effects of wind power fluctuation. Meanwhile, a combination of quantum-inspired binary gravitational search algorithm and chance constrained programming is proposed to solve the thermal unit commitment problem with wind power integration. In order to reduce the searching time and avoid the premature convergence, a priority list of thermal units and a local mutation adjustment strategy are utilized during the optimization process. The priority list of thermal units is based on the weight between average full-load cost and maximal power output. Then, a stochastic simulation technique is used to deal with the probabilistic constraints. In addition, heuristic search strategies are used to handle deterministic constraints of thermal units. Furthermore, the impacts of different confidence levels and different prediction errors of wind fluctuation on system operation are analyzed respectively. The feasibility and effectiveness of the proposed method are verified by the test system with wind power integration, and the results are compared with those using binary gravitational search algorithm and binary particle swarm optimization. The simulation results demonstrate that the proposed quantum-inspired binary gravitational search algorithm has a higher efficiency in solving thermal unit commitment problem with wind power integration. [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cells (PEMFCs) are devices that attract the interest for a variety of applications including portable devices, transportation and stationary power. Several models are available in the literature concerning PEMFCs with different modelling approaches. In this paper, two representative dynamic models are examined, one using an electrical equivalent and one based on semi-empirical equations. Moreover, an enhanced model based on semi – empirical equations and a simplified transfer function representation for the dynamic response is proposed. All models can be easily incorporated in power system simulation software. Scope of this paper is to present a parametric analysis method in order to determine the ability of each model to represent accurately the steady – state as well as the slow and fast dynamics of a PEMFC. The influence of each specific parameter is investigated and the tuning procedure is described. Finally, simulation results are presented and the adaptability of all models is evaluated. [ABSTRACT FROM AUTHOR]

This work presents the use of the modern software tool Alternative Transients Program (ATP) in the teaching of power engineering, within the course Computer Aided Engineering. A simulation model is presented through which it is possible to analyse the effects of distributed generators (DG) on the operation of a distribution network in both a steady and a transient state, with the objective of fulfilling the conditions for connection. This problem was selected not only because it allows students to gain proper insight into the phenomena within a distribution network with a connected distributed generator, but also because it has been shown that the problem of educating engineers is often a constraining factor for implementing distributed generation (DG). It is shown that by using the software tool ATP-EMTP, very complex phenomena in large networks can be studied without great difficulty or the need for analytical methods. The problem-based learning (PBL) method was applied. [ABSTRACT FROM AUTHOR]