Showing papers on "Power system simulation published in 2001"
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TL;DR: A genetic algorithm to seek the optimal location of multi-type FACTS devices in a power system and shows that the simultaneous use of several kinds of controllers is the most efficient solution to increase the loadability of the system.
Abstract: This paper presents a genetic algorithm to seek the optimal location of multi-type FACTS devices in a power system. The optimizations are performed on three parameters: the location of the devices, their types, and their values. The system loadability is applied as a measure of power system performance. Four different kinds of FACTS controllers are used and modeled for steady-state studies: TCSC, TCPST, TCVR, and SVC. Simulations are done on a 118-bus power system for several numbers of devices. Results show the difference of efficiency of the devices used in this context. They also show that the simultaneous use of several kinds of controllers is the most efficient solution to increase the loadability of the system. In all the cases (single-and multi-type FACTS devices), we observe a maximum number of devices beyond which this loadability cannot be improved.
775 citations
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TL;DR: In this paper, the authors assess the capability of the emerging synchronized phasor measurement technology in improving the overall stability of the Hydro-Quebec transmission system through supplementary modulation of voltage regulators.
Abstract: The aim of this paper is to assess the capability of the emerging synchronized phasor measurement technology in improving the overall stability of the Hydro-Quebec transmission system through supplementary modulation of voltage regulators. Following a thorough singular value and eigenvalue analysis of the system dynamic interactions, five control sites consisting of four generators and one synchronous condenser are chosen to implement new power system stabilizers with a supplementary input from remote phasor measuring units, geographically spread over nine electrically coherent areas. Since the remote feedback loops are built on top of an existing decentralized control system, this design approach results in a decentralized/hierarchical control architecture with significant advantages in terms of reliability and operational flexibility. A systematic control and measurement pairing yielded four dominant natural loops, each associated with a significant open-loop inter-area oscillatory mode at 0.06, 0.4, 0.7 and 0.95 Hz respectively. These PSSs have a speed sensitive local loop operating in the usual way, and a wide-area measurement based global loop which involves a single differential frequency signal between two suitably selected areas. The tuning and coordination technique for these advanced multiple input signals PSSs is described. Their impacts on the system is assessed using both small-signal analysis and nonlinear simulations in a transient stability program. Wide-area stabilizing controllers have a significant potential in improving the dynamic performance of the Hydro-Quebec's existing power system.
619 citations
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TL;DR: In this paper, the traditional automatic generation control (AGC) two-area system is modified to take into account the effect of bilateral contracts on the dynamics of the system, and the concept of distribution companies (DISCO) participation matrix to simulate these bilateral contracts is introduced and reflected in the two area block diagram.
Abstract: In this paper, the traditional automatic generation control (AGC) two-area system is modified to take into account the effect of bilateral contracts on the dynamics. The concept of distribution companies (DISCO) participation matrix to simulate these bilateral contracts is introduced and reflected in the two-area block diagram. Trajectory sensitivities are used to obtain optimal parameters of the system using a gradient Newton algorithm.
474 citations
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TL;DR: In this article, the authors present a graphical approach for modeling and analysis of custom power controllers, a new generation of power electronics-based equipment aimed at enhancing the reliability and quality of power flows in lowvoltage, distribution networks.
Abstract: This paper addresses the timely issue of modeling and analysis of custom power controllers, a new generation of power electronics-based equipment aimed at enhancing the reliability and quality of power flows in low-voltage, distribution networks [2],[3] The modeling approach adopted in this article is graphical in nature, as opposed to mathematical models embedded in code using a high-level computer language The well-developed graphic facilities available in an industry standard power system package, namely, PSCAD/EMTDC, are used to conduct all aspects of model implementation and to carry out extensive simulation studies Graphics-based models suitable for electromagnetic transient studies are presented for the following three custom power controllers: the distribution static compensator (D-STATCOM), the dynamic voltage restorer (DVR), and the solid-state transfer switch (SSTS) Comprehensive results are presented to assess the performance of each device as a potential custom power solution The paper is written in a tutorial style and aimed at the large PSCAD/EMTDC user base
360 citations
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TL;DR: Numerical experiences show that the solution technique is computationally efficient, simple, and suitable for decision support of short-term hydro operations planning and can be easily extended for scheduling applications in deregulated environments.
Abstract: This paper describes experiences with mixed integer linear programming (MILP) based approaches on the short-term hydro scheduling (STHS) function. The STHS is used to determine the optimal or near-optimal schedules for the dispatchable hydro units in a hydro-dominant system for a user-definable study period at each time step while respecting all system and hydraulic constraints. The problem can be modeled in detail for a hydro system that contains both conventional and pumped-storage units. Discrete and dynamic constraints such as unit startup/shutdown and minimum-up/minimum-down time limits are also included in the model for hydro unit commitment (HUC). The STHS problem is solved with a state-of-the-art package which includes an algebraic modeling language and a MILP solver. The usefulness of the proposed solution algorithm is illustrated by testing the problem with actual hydraulic system data. Numerical experiences show that the solution technique is computationally efficient, simple, and suitable for decision support of short-term hydro operations planning. In addition, the proposed approaches can be easily extended for scheduling applications in a deregulated environment.
251 citations
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TL;DR: In this article, a global controller is proposed to co-ordinate the transient stabilizer and voltage regulator, which is smooth and robust with respect to different transient faults in a single-machine infinite bus power system.
Abstract: Summary form only given as follows. This paper is concerned with the global control of power systems. It arises from the practical concern that transient stability and voltage regulation are both important properties of power system control, but they are ascribed to different model descriptions and relate to different stages of system operation (i.e. transient period and post-transient period respectively). Earlier control results deal with the two problems separately, or employ a switching strategy of two different kinds of controllers, which causes a discontinuity of system behavior. We design in this paper a global controller to co-ordinate the transient stabilizer and voltage regulator. The designed controller is smooth and robust with respect to different transient faults. Simulations on a single-machine infinite bus power system have demonstrated better performances compared with existing controllers.
178 citations
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TL;DR: In this paper, a global tuning procedure for FACTS device stabilizers and power system stabilizers in a multi-machine power system using a parameter-constrained nonlinear optimization algorithm implemented in a simulation program is presented.
Abstract: This paper presents a global tuning procedure for FACTS device stabilizers (FDS) and power system stabilizers (PSS) in a multi-machine power system using a parameter-constrained nonlinear optimization algorithm implemented in a simulation program. This algorithm deals with such an optimization problem by solving a sequential quadratic programming using the dual algorithm. The main objective of this procedure is to simultaneously optimize pre-selected parameters of the FDSs and PSSs having fixed parameters in coping with the complex nonlinear nature of the power system. By minimizing a nonexplicit target function in which the oscillatory rotor modes of the generators involved and suing characteristics between areas are included, interactions among the FACTS controls under transient conditions in a multimachine power system are improved. A multimachine power system equipped with a TCSC and an SVC as well as three PSSs is applied to demonstrate the efficiency and robustness of the tuning procedure presented. The results obtained from simulations validate the improvement in damping of overall power oscillations in the system in an optimal and globally coordinated manner. The simulations also show that the stabilizers tuned are robust in providing adequate damping for a range of conditions in the system.
175 citations
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09 Dec 2001TL;DR: This introduction to simulation tutorial is designed to teach the basics of simulation, including structure, function, data generated, and its proper use, as well as discussion on issues concerning the use of simulation in industry.
Abstract: Simulation is a powerful tool if understood and used properly. This introduction to simulation tutorial is designed to teach the basics of simulation, including structure, function, data generated, and its proper use. The introduction starts with a definition of simulation, goes through a talk about what makes up a simulation, how the simulation actually works, and how to handle data generated by the simulation. Throughout the paper, there is discussion on issues concerning the use of simulation in industry.
160 citations
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15 Jul 2001TL;DR: In this paper, a novel evolutionary algorithm based approach to optimal design of multimachine power system stabilizers (PSSss) is proposed, which develops and employs particle swarm optimization (PSO) technique to search for optimal settings of PSS parameters.
Abstract: In this paper, a novel evolutionary algorithm based approach to optimal design of multimachine power system stabilizers (PSSs) is proposed. The proposed approach develops and employs particle swarm optimization (PSO) technique to search for optimal settings of PSS parameters. Two eigenvalue-based objective functions to enhance system damping of electromechanical modes are considered. The robustness of the proposed approach to the initial guess is demonstrated. The performance of the proposed PSO based PSS (PSOPSS) under different disturbances and loading conditions is tested and examined. Eigenvalue analysis and nonlinear simulation results show the effectiveness of the proposed PSOPSSs to damp out the electromechanical oscillations and work effectively over a wide range of loading conditions.
133 citations
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10 Sep 2001TL;DR: In this article, the authors present a solution to the problem of calculating the initial conditions of the dynamic model from load flow data to be able to initialize the dynamic simulation correctly, in which wind turbine models are integrated to enable the investigation of increasing wind turbine penetration on power system behavior.
Abstract: As a result of increasing environmental concern, increasing amounts of electricity are generated from renewable sources. One way of generating electricity from renewable sources is to use wind turbines. A tendency to erect more wind turbines can be observed. As a result of this, in the near future wind turbines may start to influence the behavior of electrical power systems. To investigate the impact of increasing wind turbine penetration, power system dynamics studies need to be carried out. To this end, power system dynamics simulation software is used, in which wind turbine models must be integrated to enable the investigation of increasing wind turbine penetration on power system behavior. If wind turbine models are to be integrated into power system dynamics simulation software, it must be possible to calculate the initial conditions of the dynamic model from load flow data to be able to initialize the dynamic simulation correctly. In this paper, a solution to this problem is presented.
129 citations
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TL;DR: Two parallel methodologies for composite reliability evaluation using sequential Monte Carlo simulation based on coarse grain asynchronous implementations are described, which show high speedup and efficiency on both parallel platforms.
Abstract: This paper describes two parallel methodologies for composite reliability evaluation using sequential Monte Carlo simulation. The methodologies are based on coarse grain asynchronous implementations. In the first methodology, a complete simulation year is analyzed on a single processor and the many simulated years necessary for convergence are analyzed in parallel. In the second methodology, the adequacy analysis of the system operating states within the simulated years is performed in parallel and the convergence is checked on one processor at the end of each simulated year. The methodologies are implemented on a 10 nodes IBM RS/6000 SP scalable distributed memory parallel computer and on a network of 8 IBM RS/6000 43P workstations. The results obtained in tests with actual power system models showed high speedup and efficiency on both parallel platforms.
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TL;DR: In this article, a bidding strategy based on the theory of ordinal optimization is presented, where the ordinal comparisons of performance measures are robust with respect to noise and modeling error, and the problems become much easier if the optimization goal is softened from asking for the "best" to "good enough" solution.
Abstract: The deregulation and reconstruction of the electric power industry worldwide raises many challenging issues related to the economic and reliable operation of electric power systems. Traditional unit commitment or hydrothermal scheduling problems have been integrated with generation resource bidding, but the development of optimization based bidding strategies is only at a very preliminary stage. This paper presents a bidding strategy based on the theory of ordinal optimization that the ordinal comparisons of performance measures are robust with respect to noise and modeling error, and the problems become much easier if the optimization goal is softened from asking for the "best"" to "good enough" solution. The basic idea is to use an approximate model that describes the influence of bidding strategies on the market clearing prices (MCP). A nominal bid curve is obtained by solving optimal power generation for a given set of MCPs via Lagrangian relaxation. Then N bids are generated by perturbing the nominal bid curve. The ordinal optimization method is applied to isolate a good enough set S that contains some good bids with high probability by performing rough evaluation. The best bid is then selected by solving full hydrothermal scheduling or unit commitment problems for each of the bids in S. Using ordinal optimization approach we are able to obtain a good enough bidding strategy with reasonable computational effort. Numerical results using historical MCPs from the California market and a generation company with 10 units show that the ordinal optimization based method is efficient.
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TL;DR: A novel concept for power quality study that integrates the power system modeling, classifying, and characterizing of power quality events, studying equipment sensitivity to the event disturbance and locating the point of event occurrence into one unified frame is proposed.
Abstract: A novel concept for power quality study is proposed. The concept integrates the power system modeling, classifying, and characterizing of power quality events, studying equipment sensitivity to the event disturbance and locating the point of event occurrence into one unified frame. Both Fourier and wavelet analyses are applied for extracting distinct features of various types of events as well as for characterizing the events. A new fuzzy expert system for classifying power quality events based on such features is presented with improved performance over previous neural network-based methods. A novel simulation method is outlined for evaluating the operating characteristics of the equipment during specific events. A software prototype implementing the concept has been developed in MATLAB. The voltage sag event is taken as an example for illustrating the analysis methods and software implementation issues. It is concluded that the proposed approach is feasible and promising for real world applications.
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TL;DR: A fuzzy decision making approach has been developed to solve the unit commitment problem and to train the artificial neural network to incorporate the changes due to the addition of new constraints automatically, an expert system (ES).
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TL;DR: In this article, the authors investigate market power issues in bid-based hydrothermal scheduling, where market power is simulated with a single-stage Nash-Cournot equilibrium model and market power assessment for multiple stages is carried through a stochastic dynamic programming scheme.
Abstract: The objective of this paper is to investigate market power issues in bid-based hydrothermal scheduling. Initially, market power is simulated with a single-stage Nash-Cournot equilibrium model. Market power assessment for multiple stages is then carried through a stochastic dynamic programming scheme. The decision in each stage and state is the equilibrium of a multi-agent game. Thereafter, mitigation measures, specially bilateral contracts, are investigated. Case studies with data taken from the Brazilian system are presented and discussed.
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TL;DR: In this paper, the authors explored the inherent characteristics of multi-grounded three-phase four-wire distribution systems under unbalanced situations and explored the effects of neutrals and system grounding.
Abstract: This paper has explored the inherent characteristics of multi-grounded three-phase four-wire distribution systems under unbalanced situations. The exploration also involved the effects of neutrals and system grounding. Power engineers have often disregarded these effects while analyzing a power system. The simulation tool is PSpice for Windows. It is capable of representing and simulating the equivalent model with an explicit neutral wire and groundings of a multi-grounded distribution system. In this paper the equivalent model of a full-scale multi-grounded distribution system implemented by PSpice is introduced. Simulation results have illustrated the effects of neutrals and system grounding on the operation characteristics of multi-grounded four-wire distribution systems.
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TL;DR: In this article, a new approach for the real-time digital simulation of power electronic controllers in power systems is presented, which combines the variable step-size numerical integration method with linear interpolation for the synchronization of a realtime digital simulator and a digital controller.
Abstract: This paper presents a new approach for the real-time digital simulation of power electronic controllers in power systems. Digital controllers for power electronic systems present a problem when testing in real-time using a digital simulator due to the discrete nature of their outputs, which are not necessarily in synchronism with the time step of the simulator. The proposed algorithm combines the variable step-size numerical integration method with linear interpolation for the synchronization of a real-time digital simulator and a digital controller. It is shown that lack of such synchronization leads to inaccurate simulation results, specifically with regard to the fundamental and harmonics of the voltage and current signals. Sampling theory is used to model the interaction between a digital simulator and a digital controller. A pulse width modulated (PWM) voltage source converter (VSC) based reactive power compensator system is used as an illustrative example for the simulation.
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15 Jul 2001TL;DR: In this paper, the modeling of wind turbines in power system dynamics simulations is discussed and the three most important actual wind turbine concepts are described, and various classes of wind turbine models are introduced.
Abstract: In this panel contribution, the modeling of wind turbines in power systems dynamics simulations is discussed. First the three most important actual wind turbine concepts are described. Then, various classes of wind turbine models are introduced and it will be discussed which model type can be integrated in power system dynamics simulation software. To conclude, it will be argued that it is possible to model various kinds of variable speed wind turbines with only one model in power system dynamics simulations.
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28 Oct 2001
TL;DR: The paper presents the basics of the wavelet transforms technique in power systems terminology and illustrates its use in the new algorithm, showing that the proposed algorithm offers a fast and secure technique for fault classification inPower systems.
Abstract: This paper presents a new approach to fault classification on transmission lines for high speed protective relaying. The scheme is based on the use of wavelet transform and implementation of digital signal processing concepts. It uses samples from the three line currents. The data window is 6 samples based on 10 kHz sampling rate. The new technique is tested on data simulated on EMTP for the 11 types of faults at different fault locations, different fault resistances, different fault inception angles, and different system parameters. The test results showed that the proposed algorithm offers a fast and secure technique for fault classification in power systems. The paper presents the basics of the wavelet transforms technique in power systems terminology and illustrates its use in the new algorithm.
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TL;DR: In this article, the impact of load models on an unstable low frequency oscillation damping, which recently occurred in the Taiwan power system, was also investigated, using the eigenvalue analysis approach.
Abstract: This paper uses the eigenvalue analysis approach to observe the impact of load models on an unstable low frequency oscillation damping, which recently occurred in the Taiwan power system. In order to enhance oscillation damping, the effect of load models on power system stabilizers is also investigated. Three kinds of the derived load models (a dynamic model, a composite model, and an exponential model) based on the component approach with the measured characteristics of power system loads are used in this paper. Time simulation results are extensively used to verify the eigenvalue analysis results with and without power system stabilizers. One set of field test data obtained from the Taiwan power nuclear plant with power system stabilizers is used to determine which load model provides a more accurate result in enhancement of oscillation damping. Depending on the results, the effect of load models on electromechanical oscillation damping with and without power system stabilizers is verified.
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10 Sep 2001
TL;DR: In this paper, a load-frequency control problem in a three-area interconnected power system such that two areas include steam turbines and the other area includes a hydro turbine is considered, and a back propagation-through-time algorithm is used as a neural network learning rule.
Abstract: This paper includes an application of layered artificial neural network controller to study the load-frequency control problem in a power system. The control scheme guarantees that steady state error of frequencies and inadvertent interchange of tie-lines are maintained in a given tolerance limitation. The proposed control has been designed for a three-area interconnected power system such that two areas include steam turbines and the other area includes a hydro turbine. Only one artificial neural network (ANN) controller, which controls the inputs of each area in the power system together, is considered. In the study, a back propagation-through-time algorithm is used as a neural network learning rule. The performance of the power system is simulated by using a conventional integral controller and ANN controller, separately. By comparing the results for both cases, the performance of an ANN controller is better than conventional controllers.
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TL;DR: In this article, a decentralized operation of the transmission grid for scheduling inter-utilities power exchanges is proposed, which achieves a market equilibrium while the operational independence of each interconnected utility is preserved.
Abstract: A decentralized operation of the transmission grid for scheduling inter-utilities power exchanges is proposed. This approach is well suited for market-oriented environments; it achieves a market equilibrium while the operational independence of each interconnected utility is preserved. We employ decomposition-coordination techniques in combination with an interior-point/cutting-plane method in order to reduce the number of iterations of the decomposition algorithm. The paper includes test results on IEEE-based systems.
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TL;DR: In this paper, a random search algorithm based on power system heuristics is given for fast rare-event simulation of consecutive relaying malfunctions in bulk power systems and an economical system upgrading strategy that can best enhance the protection system reliability under limited budget.
Abstract: Recent studies have shown that hidden failures in the protective devices have a great impact on the power system reliability. In this paper, the authors provide definitions of vulnerability and reliability of protection systems to numerically characterize this impact. A random search algorithm based on power system heuristics is given for fast rare-event simulation of consecutive relaying malfunctions in bulk power systems. They also propose an economical system upgrading strategy that can best enhance the protection system reliability under limited budget. Finally, they present the result of a case study on New York Power Pool (NYPP) 3000-bus system.
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03 Jan 2001TL;DR: A fuse model using DC load flow and fuse protection is presented to simulating the cascading events in power transmission networks and finds that the probability density of time intervals between disturbances can be given an exponential fit.
Abstract: In this paper, NERC (North American Reliability Council) records of power System disturbances for the year 1984 through 1999 are explored. The disturbance sizes show a power law distribution, which confirms the early results [2]. Further, we find that the probability density of time intervals between disturbances can be given an exponential fit. Based on this observation, the suitability of applying SWV analysis to power system disturbance data is questioned. An artificial time series is constructed to support our idea. A fuse model using DC load flow and fuse protection is presented to simulating the cascading events in power transmission networks. Some initial simulation results are shown to be consistent with NERC data. Besides SOC and HOT, this model gives another way to investigate power law behavior in power system disturbances.
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10 Sep 2001TL;DR: Simulation analyses of transient stability of a power system including an induction generator performed by PSCAD/EMTDC are presented.
Abstract: Induction machines are mostly used as generators in wind power stations. Since induction machines also have a stability problem, it is important to analyze the transient stability of the power system including wind power stations. This paper presents simulation analyses of transient stability of a power system including an induction generator performed by PSCAD/EMTDC.
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29 Nov 2001TL;DR: In this paper, a unified method for modeling and simulation of electrical drives using state-space formulation in MATLAB/Simulink is presented, which has been successfully implemented in a simulation package called "Power System Blockset" (PSB) for use in MATLab/simulink environment.
Abstract: This paper presents a unified method for modeling and simulation of electrical drives using state-space formulation in MATLAB/Simulink. The proposed method has been successfully implemented in a simulation package called "Power System Blockset" (PSB) for use in MATLAB/Simulink environment. The principle of the modeling and simulation method is presented and the PSB operation is described. Application examples including a DC brushless motor drive and a direct torque control (DTC) induction motor drive are presented. Simulation results obtained with the PSB are presented to illustrate its possibilities.
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TL;DR: In this paper, the performance of a wavelet-based, on-line (real-time) voltage detection scheme for power quality applications is evaluated, and the authors demonstrate suitability of the proposed method in detecting faults/disturbances in a power system and compare its performance with that of a conventional scheme.
Abstract: This article evaluates the performance of a wavelet-based, on-line (real-time) voltage detection scheme for power quality applications. The objectives are (1) to demonstrate suitability of the proposed method in detecting faults/disturbances in a power system and (2) to compare its performance with that of a conventional scheme. Two static transfer switch (STS) systems are chosen as frameworks for comparison; a low-voltage laboratory STS set-up for which measured results are provided, and a medium-voltage STS system for which detection times are derived based on simulation, using the EMTDC/PSCAD.
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TL;DR: In this article, a review of characteristics and modeling of major power electronic types of harmonic sources for the power system harmonic analysis is presented, including static power converters, static var compensators (SVCs), and cycloconverters.
Abstract: This paper presents a review of characteristics and modeling of major power electronic types of harmonic sources for the power system harmonic analysis. The power electronic switching types of harmonic sources to be reviewed include static power converters, static var compensators (SVCs), and cycloconverters. Discussions and comtnents for applications of these harmonic sources in harmonic modeling and simulation also will be described.
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TL;DR: In this article, the authors investigated the application of genetic algorithms to optimize large, nonlinear complex systems, particularly the optimization of the operation planning of hydrothermal power systems, and presented the adaptation of the technique and an actual application on the optimization for a cascade system composed by interconnected hydroelectric plants.
Abstract: This paper investigates the application of genetic algorithms to optimize large, nonlinear complex systems, particularly the optimization of the operation planning of hydrothermal power systems. Several of the current studies to solve this kind of problem are based on nonlinear programming. This approach presents some deficiencies, such as difficult convergence, oversimplification of the original problem, or difficulties related to the objective function approximation. Aiming to find more efficient solutions for this class of problems, this paper proposes and investigates the use of a genetic approach. The characteristics of the genetic algorithms, such as simplicity, parallelism, and generality, can provide an effective solution to these problems. The paper presents the adaptation of the technique and an actual application on the optimization of the operation planning for a cascade system composed by interconnected hydroelectric plants
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TL;DR: An object-oriented power system simulation environment is constructed using the SIMULINK dynamic system modeling software, which provides an excellent simulation engine for the nonlinear models.
Abstract: An object-oriented power system simulation environment is constructed using the SIMULINK dynamic system modeling software. The environment is well suited to educational purposes, because the user interface is interactive and intuitive with a graphical, object-oriented model representation. For small system studies, a model is constructed in block diagram form with one block for each system component. For large scale simulations, the dynamics of portions of the network can be combined into collective blocks, with parameters managed as data arrays accessed indirectly using string mnemonics. The advanced numerical capabilities built into SIMULINK provide an excellent simulation engine for the nonlinear models. Offline analysis is available through the extensive capabilities of the MATLAB environment.