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Showing papers on "Power system simulation published in 1986"


Journal ArticleDOI
TL;DR: In this article, the authors developed a realistic model for short-term operation planning of a large scale hydrothermal power system with a high share of hydro, where the Benders method was employed to decompose the problem with respect to integer and continuous variables.
Abstract: This paper develops a realistic model for short-term operation planning of a large scale hydrothermal power system with a high share of hydro. This problem is a large scale mixed integer program. Benders' method is employed to decompose the problem with respect to integer and continuous variables. The master problem of this method contains only integer variables and considers the unit commitment of thermal plants. The subproblem includes only continuous variables and considers the economic dispatch problem. The special structure of master and subproblems are further exploited which results in considerable reductions in the size of the problem and computation time requirement.

164 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a procedure for solving the short-term generation scheduling problem for a large hydrothermal system that includes transmission limitations, where the integrated system is divided into a hydro and a thermal subsystem.
Abstract: This paper presents a procedure for solving the short term generation scheduling problem for a large hydrothermal system that includes transmission limitations. The integrated system is divided into a hydro and a thermal subsystem. A reduced gradient algorithm is employed for the solution of the hydro subproblem. This algorithm is specialized to efficiently solve nonlinear network flow problems with additional constraints of non-netwrk type. The thermal subsystem is solved using a fast unit commitment and dispatch algorithm. A case study with the Swedish system is discussed.

93 citations


Journal ArticleDOI
TL;DR: In this paper, a method for determining the costeffectiveness of wind energy and the economic limitations of penetration into electrical power systems is presented based on a Monte-Carlo approach which simulates the hour-byhour operation of the power system.
Abstract: A method for determining the costeffectiveness of wind energy and the economic limitations of penetration into electrical power systems is presented. It is based on a Monte-Carlo approach which simulates the hour-by-hour operation of the power system. The hourly random variations in wind and load are modeled in addition to the operating constraints inherent in conventional generation. The economic assessment is based on a selected one-year simulation period, Two examples of the application of this method are given.

74 citations


Journal ArticleDOI
P.L. Dandeno1
TL;DR: The main areas of interest for generator electrical modelling can be categorized into four general areas (I) through (IV) noted Symposium on ''Synchronous Machine Modelling for below: (Only two of these areas, ie, II and III Power System Studies', (IEEE 83 TH0101-6-PWR). In will be covered in detail in this current paper as discussed by the authors.
Abstract: As a prelude to discussing some of the issues of prime interest to those concerned with the appropriate use of stability models, the Task Force A. INTRODUCTION believes the principal areas of interest for generator electrical modelling can be categorized This paper is being produced as a follow-up to the into four general areas (I) through (IV) noted Symposium on \"Synchronous Machine Modelling for below: (Only two of these areas, ie, II and III Power System Studies', (IEEE 83 TH0101-6-PWR). In will be covered in detail in this current paper). the symposium publication, discussed at the IEEE-PES Winter Power Meeting in 1983, the Joint Working (I) Short circuit, faults, and relay application Group, through a series of individual papers, gave studies. Parameters are required to obtain an overview of various approaches which have been initial R.M.S. current values or R.M.S. values used, or are currently being developed, to produce of current after subtransient currents have parameters for stability models. The complexities decayed. More complex studies can be possible in model availability were covered only performed including determination of dc offset briefly. Furthermore, the limitations in parameters values for specifying breaker ratings more obtained from data, obtained using either \"Standard\" precisely. methods, or using newly proposed methods, were not investigated or delineated in any depth. (II) Stability Studies (Large Disturbances, Non-Linear). Such analysis can include Another important factor, not given much treatment various types of time domain stability at the Symposium, was how saturation should be studies. Included are such examples as: treated in stability studies. It has been customary to consider a \"total\" saturation during the . First angular swing, no exciters, no initialization stage of stability studies, and also saliency (constant voltage behind a fixed during subsequent step by step calculations in time reactance). This approach, once common, is domain simulations. However, the application of now used infrequently for particular saturation factors to \"Unsaturated Models\" had not investigations of generating station been clearly demonstrated or fully justified in any stability limits. However, it is often used of the Symposium articles. Also the effects of to approximate the transient time-angle incremental changes in permeability (or saturation) response of machines or groups of machines have been covered in very few publications. The electrically remote from the principal area consideration of such effects in small signal or of investigation. The inertial effects of linearized stability analyses has been given limited such remote machines are important. recognition or study. First angular swing, with saliency The Joint Working Group feels that the above issues represented, both in the steady state and should be brought to the industries' attention, and transient state (constant field flux we welcome comments from both \"producers\" of linkages in the direct axis). This is an stability data, as well as from the many \"users\" of extension of the more commonly used approach such data. It is the Joint Working Group's described above. It is seldom used, since objective, in accordance with its scope, to the approximations made for the \"constant eventually produce a recommended set of Guidelines voltage\" approach provide acceptable results. for using various models in different types of stability studies, along with concordant procedures . Two or three time-angle rotor swings are for obtaining data for such models. often calculated principally of dominant

66 citations


Journal ArticleDOI
TL;DR: In this paper, an optimal control strategy for improved dynamic performance of integrated ac/dc systems, based on power modulation techniques, is developed and applied to a typical AC/dc system with non-linearly voltage dependent load.
Abstract: This paper develops an optimal control strategy for improved dynamic performance of integrated ac/dc systems, based on power modulation techniques. The basic feature of the method is the minimization of the adverse reactive power interactions between the controls and voltage sensitive loads, which tend to reduce the effectiveness of the modulation process. A method for stability analysis, based on linearization techniques and eigenvalue sensitivities, is developed and applied to a typical ac/dc system with non-linearly voltage dependent load. The dynamic performance of the system, both with dc power modulation and power system stabilizer, is evaluated for various operating conditions, different load characteristics and different excitation systems. Finally, a dynamic simulation program is developed and used to obtain the exact transient response of the ac/dc system in the time domain. The simulation results presented in the paper verify the responses predicted from the linear eigenvalue sensitivity analysis.

33 citations


Journal ArticleDOI
TL;DR: This paper presents a dynamic load flow technique for power system simulators that possesses all the attractive features and basic structure of the normal fast decoupled method, and it does not depend on the selected reference bus.
Abstract: This paper presents a dynamic load flow technique for power system simulators. The approach presented can be applied to a system when there is a net accelerating or decelerating power in the system. It possesses all the attractive features and basic structure of the normal fast decoupled method, and it does not depend on the selected reference bus. The modifications to the standard fast decoupled power flow algorithm are derived, and power system simulator implementation considerations are discussed. The algorithm has been tested on standard IEEE test cases and on a metropolitan utility 559 bus model. A numerical example of the above algorithm on the 559 test case is presented which demonstrates convergence characteristics and computation requirements of the proposed algorithm. These results are compared with those of normal fast decoupled load flow.

31 citations


Journal ArticleDOI
TL;DR: In this paper, an iterative method is developed for synthesizing one-port equivalent networks by the removal of poles corresponding to resonances of the driving-point impedance or admittance function.
Abstract: Equivalent networks can be used in power system simulation to reduce simulation equipment or computer time and memory space. In this paper, an iterative method is developed for synthesizing one-port equivalent networks by the removal of poles corresponding to resonances of the driving-point impedance or admittance function. This results in networks formed by the series or parallel connection of modular RLC circuits. The RLC values are calculated using a parameter-optimization technique. Multi-port equivalent networks are first configured as ? or T forme composed of one-port network branches and the latters are then synthesized by the proposed method for one-port equivalent networks.

28 citations


Journal ArticleDOI
D. N. Ewart1
TL;DR: In this article, differential equations describing a single-phase, multi-winding, steel-core transformer are derived to represent hysteresis, saturation and eddy current effects.
Abstract: Differential equations describing a single-phase, multi-winding, steel-core transformer are developed. Non-linear, time-dependent equations are derived to represent hysteresis, saturation and eddy current effects. An efficient solution algorithm is presented and simulation results using equations and the algorithm are included. The resulting model forms a needed addition to existing simulation programs.

28 citations


Journal ArticleDOI
TL;DR: In this paper, the invariant imbedding non-linear dynamic estimation technique is used to determine the transient state of a power system, in the presence of system input disturbance and measurement noise.
Abstract: This paper describes the application of the invariant imbedding non-linear dynamic estimation technique to determine the transient state of a power system. The estimator handles system and measurement non-linearities effectively and works in the presence of system input disturbance and measurement noise. Off-line computer simulations of the estimator applied to a single machine infinite busbar power system successfully estimated the states of the machine. The results indicated that successful estimation is achieved by a careful choice of the input disturbance noise covariance matrix, Q. High Q values are recommended for the stepout region and low Q values for the hunting region.

26 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present main characteristics of longitudinal power systems and common operating problems and illustrate the examples included in the paper are based on simulations using real longitudinal power system, where voltage control, transient stability and frequency dynamics are analyzed.
Abstract: In the last decade modern control centers with advanced security functions have been installed in several countries. However most security applications have been based on steady state calculations, mainly because for those systems typical operating problems can be assessed using steady state analyses. Many power systems around the world, specially in developing countries, are characterized by a weak longitudinal structure. For these systems operating problems and system security are closely related to system configuration. The paper presents main characteristics of longitudinal power systems and common operating problems are described and illustrated. The examples included in the paper are based on simulations using real longitudinal power systems. For these systems dynamic security analyses are required to assess system performance. Main areas of study are voltage control , transient stability and frequency dynamics. Basic simulation tools are described and operating strategies presented.

24 citations


Journal ArticleDOI
TL;DR: In this paper, the main characteristics of a digital computer package for solving the complex problem of Short-Term Hydro-thermal unit commitment in medium and large size power systems (over 150 units) are presented.
Abstract: The main characteristics of a digital computer package for solving the complex problem of Short-Term hydro-thermal unit commitment in medium and large size power systems (over 150 units) are presented. The over-all system design criteria, including Man Machine Interface (MMI), the software tools that support the analysis of the large volume of information required for unit commitment planning, and the optimization algorithms are discussed in the text. The package has been tested on a medium-size power system model.

Journal ArticleDOI
TL;DR: The paper describes the computerized algorithm as well as numerical results for the IEEE 118-bus power system to demonstrate the applicability of the algorithm to actual systems.
Abstract: This paper presents a combined optimization/reliability technique to evaluate the reliability of large power systems. It uses Monte Carlo simulation for the individual operation/failure random performance of elements of a power network. This simulation overcomes the difficulty in constructing the many possible states for large power systems of complex topology. A simplified power-flow representation of the power network is used and a network reduction is implemented to reduce the size of the power-flow problem, such that only the effective part of the network (for a given contingency) is retained. The control parameters are optimized in order to simulate practical contingency situations in which suitable controls are invoked to preserve, as much as possible, the continuity of supply. The optimization problem is solved by linear programming in which the generator powers are manipulated as optimization variables to maximize the load power supplied and subject to the power flow equations as well as upper and lower bounds on the optimization variables. The outputs of the performance simulation and the optimization problem are subsequently used to compute the system reliability indices. The paper describes the computerized algorithm as well as numerical results for the IEEE 118-bus power system to demonstrate the applicability of the algorithm to actual systems.

Journal ArticleDOI
TL;DR: In this paper, the feasibility of using an online method to coordinate the dc injections of a multiterminal dc system to dynamically control the power flows in certain ac lines of an integrated ac-dc power system was investigated.
Abstract: As more dc terminals, in the form of links or multiterminal systems, come into operation, the opportunity for controlling ac line flows using the injected dc powers increases. This paper describes a study undertaken to determine the feasibility of using an on-line method to coordinate the dc injections of a multiterminal dc system to dynamically control the power flows in certain ac lines of an integrated ac-dc power system. The proposed controller can be used to steer and to regulate the power flows, and also to damp the power oscillations in these ac lines. The effectiveness of the controller is demonstrated using a transient simulation program.

Journal ArticleDOI
TL;DR: The current status of long term power system dynamic simulation at the conclusion of EPRI RP1469-1 project is summarized in this article, focusing upon future usage of the simulation.
Abstract: The current status of long term power system dynamic simulation at the conclusion of EPRI RP1469-1 project is summarized. Technical perspectives on the application history and simulation methodology are given first. The current status description concentrates on the program requirements, the power system models and the solution method. Discussions in relation to the actual project work are given throughout this paper, focusing upon future usage of the simulation. A number of recommendations are given to facilitate application.

Journal ArticleDOI
TL;DR: A new model generator implementation in which a microprocessor solves the discretized generator dynamic equations is described, implemented using digital hardware.
Abstract: A major shortcoming of real-time analog power system simulators has been the lack of an inexpensive and flexible dynamic generator model. This paper describes such a model, implemented using digital hardware. Issues which are addressed in the design include model-to-network interfacing, stability, accuracy, and processor architecture. Simulation results of the resulting model generator are presented. Real-time power system simulation is typically carried out on a scale model of the power system known as a Transient Network Analyzer (TNA), which consists primarily of passive component models of power system elements such as transmission lines and transformers. Several dynamic generator models have been constructed for use with TNA's with varying degrees of success. [1,2] The primary shortcomings of these implementations have been high cost and lack of flexibility. This paper describes a new model generator implementation in which a microprocessor solves the discretized generator dynamic equations. Interface to the TNA is via analog-to-digital and digital-to-analog converters. A few of the advantages to this approach are: the parameter values are easy to change, the mathematical model itself is easily modified, and the hardware is inexpensive.

Journal ArticleDOI
TL;DR: In this paper, a power system under a transmission and generation constrained economic dispatch strategy is simulated over the feasible range of system load using recently developed techniques based on the continuation method, which can be easily computed as analytic piecewise linear or quadratic functions of the system load.
Abstract: The behaviour of a power system under a transmissionand generation constrained economic dispatch strategy, is simulated over the feasible range of system load using recently developed techniques based on the continuation method. All optimum variables of interest including costs, incremental costs, power generated, power and energy flows, and the Lagrange multipliers of the active variables, can be easily computed as analytic piece-wise linear or quadratic functions of the system load. These results are combined with a load duration curve model of the probabilistic load behaviour to generate duration curve models for all the above variables. The new load duration curves then serve to generate a wide range of probabilistic measures of the system behaviour useful in the estimation of production costs,and in planning.

Patent
16 Oct 1986

Journal ArticleDOI
TL;DR: In this paper, the authors describe modifications and additions made to a static analog network analyzer to make it behave as a realistic and dynamic power system model, combined with a full-scale control system, forms a unique tool for power system control and operation studies.
Abstract: This paper describes modifications and additions made to a static analog network analyzer to make it behave as a realistic and dynamic power system model. The modified analyzer, combined with a full-scale control system, forms a unique tool for power system control and operation studies. All power system dynamics which are relevant from a control system point of view must be modelled. This implies that new power plant models and dynamic load models have been added to the analyzer. A metering system, used to measure interesting signals in the model, has also been added and serves as well as an interface to the control system The modified analyzer presented here is now a realistic model of the power system and, used with the control system, provides an excellent point of departure for further research.

Patent
09 Jul 1986

DOI
01 Jan 1986
TL;DR: The resulting integrated algorithms are capable of performing mixed-mode simulation, where a circuit is partitioned into discrete and continuous regions, and each region is simulated at the appropriate...
Abstract: This paper presents a unified approach to mixed-mode simulation. It investigates the algorithms for both logic and circuit simulation, considering their similarities and differences, and a general framework is presented for integrating the two algorithms in uniform manner. The time advance mechanisms and component functional evaluations of the algorithms are show to be similar in nature, and mechanisms for the translation of information represented uniquely in the two algorithms are given. The resulting integrated algorithms is capable of performing mixed-mode simulation, where a circuit is partitioned into discrete and continuous regions, and each region is simulated at the appropriate... Read complete abstract on page 2.

Journal ArticleDOI
TL;DR: Control requirements and computer architectures are discussed, proposing some new research areas according to past experiences and future developments of computer technology are proposed.

Book ChapterDOI
01 Jan 1986
TL;DR: An attempt of IBM Austria and STEWEAG to practically implement a short term operation planning system which is universally applicable to electric power systems and district heating systems is proposed.
Abstract: This paper deals with economical optimization in electric utilities. After a short review which summarizes the optimization activities of the Styrian electric utility STEWEAG, a report is given about an attempt of IBM Austria and STEWEAG to practically implement a short term operation planning system which is universally applicable to electric power systems and district heating systems. Some of the highlights of this optimization model are: • Complex water reservoir systems including reservoir networks, time delays for the water flow and water contracts to downstream plants • Coupled energy systems with electric and heating power generation • Sophisticated interchange contracts taking into account several types of contracts • New acceleration strategies for solving the optimization problem