Showing papers on "Power system simulation published in 1990"
TL;DR: In this article, a method for the simulation of the composite power system is proposed for the purpose of evaluating the probability distribution function of circuit flows and bus voltage magnitudes, which consists of two steps.
Abstract: A method for the simulation of the composite power system is proposed for the purpose of evaluating the probability distribution function of circuit flows and bus voltage magnitudes. The method consists of two steps. First, given the probabilistic electric load model, the probability distribution function of the total generation of generation buses is computed. Second, circuit flows and bus voltage magnitudes are expressed as linear combinations of power injections at generation buses. This relationship allows the computation of the distribution functions of circuit flows and bus voltage magnitudes. The method incorporates major operating practices such as economic dispatch and nonlinearities resulting from the power flow equations. Validation of the method is performed via Monte Carlo simulation. Typical results are presented, showing that the proposed method matches the results obtained with the Monte Carlo simulations very well. Potential applications of the proposed method are: composite power system reliability analysis and transmission loss evaluation. >
131 citations
TL;DR: The application of mathematical programming techniques to optimization in simulation, response surface methodology and designs, perturbation analysis, and frequency domain simulation experiments are discussed.
Abstract: Simulation is commonly used to find the best values of decision variables for problems which defy analytical solutions. This objective is similar to that of optimization problems and thus, mathematical programming techniques may be applied to simulation. However, the application of mathematical programming techniques, e.g., the gradient methods, to simulation is compounded by the random nature of simulation responses and by the complexity of the statistical issues involved. The literature relevant to optimization in simulation is scattered, and no comprehensive and up-to-date treatment of the subject is presently available. To that end, this article brings together numerous concepts related to t he problem of optimization in simulation. Specifically, it discusses the application of mathematical programming techniques to optimization in simulation, response surface methodology and designs, perturbation analysis, and frequency domain simulation experiments. The article provides a user with an overview of the available optimization techniues and identifies future research possibilities.
91 citations
05 Dec 1990
TL;DR: The use of real-time phasor measurements for voltage stability analysis of power systems is considered and an algorithm which achieves this goal has been developed and tested on several power systems of various sizes and structures.
Abstract: The use of real-time phasor measurements for voltage stability analysis of power systems is considered. Two schemes of phasor measurement unit (PMU) placement have been investigated. In the first scheme, PMUs are used as pilot points for the secondary voltage control of a power system. Several criteria for pilot point selections are reviewed and assessed. In the second scheme, the PMUs are used for the purpose of estimating the whole state of the system. This is a prerequisite for the determination of the voltage stability margins. The goal is to find the minimal set of PMUs that makes the system both linear and observable. By making use of the simulated annealing method, an algorithm which achieves this goal has been developed and tested on several power systems of various sizes and structures. >
89 citations
TL;DR: In this article, the authors present a comprehensive large-signal stability analysis of a solar-array power system with a typical nonlinear load characteristic, and employ stateplane analysis techniques to characterize the dynamic behavior of the system from an arbitrary initial condition.
Abstract: The authors present a comprehensive large-signal stability analysis of a solar-array power system. The stability of the equilibrium points of a system with a typical nonlinear load characteristic is analyzed. Employing state-plane analysis techniques, the dynamic behavior of the system from an arbitrary initial condition is characterized, and the region of the desired stable operation is identified. The stability and transient response of the system operation near the solar array's maximum power point are evaluated. The dynamic response of the spacecraft power system operating in the shunt mode and battery-discharge mode is analyzed. >
54 citations
TL;DR: A laboratory environment for research, teaching and demonstration of power system behavior developed at Arizona State University is described, which includes a real-time digital simulation of a large power system and a program-to-program communication specifically developed for this application.
Abstract: A laboratory environment for research, teaching and demonstration of power system behavior developed at Arizona State University is described. The main driver is a real-time digital simulation of a large power system. A full-graphic human interface made up of several levels of one-line diagrams, tables and other displays permits the observation of the power system behavior in real time; it also makes it possible to affect its behavior by introducing supervisory control actions. These programs operate on a database, which can be changed to represent different power systems. The simulation and the database are run on a VAX 11-785 mainframe computer, while the human interface is run on an Apollo DN570 workstation with a 19-inch full-graphic color display. The two computers are linked via a high-speed Ethernet data link. The program-to-program communication was specifically developed for this application. The total environment created is that of a power system control center. It can be used to demonstrate and teach power system behavior as well as to experiment with all facets of the energy management system. >
24 citations
05 Dec 1990
TL;DR: In this article, the authors outline the development of a nonlinear control law to improve the transient stability of a small parallel AC/DC power system described by nonlinear descriptor equations.
Abstract: The authors outline the development of a nonlinear control law to improve the transient stability of a small parallel AC/DC power system described by nonlinear descriptor equations. The strategy is based on feedback linearization principles. The performance of this strategy is illustrated via simulation. Preliminary results verify the effectiveness of the strategy. >
17 citations
TL;DR: In this article, a case study of the application of a distributed control scheme to a power system control is presented, in which an investigation has been conducted into voltage control and combined injection of VAr-compensating devices controlled by distributed expert systems has been proposed as a measure to maintain voltage stability under heavy loading conditions.
Abstract: A case study of the application of a distributed control scheme to a power system control is presented. In addition, an investigation has been conducted into voltage control. Combined injection of VAr-compensating devices controlled by distributed expert systems has been proposed as a measure to maintain voltage stability in a power system under heavy loading conditions. A simulation study has been carried out by using five workstations that represent a power system and four VAr-compensating devices. The results demonstrate the effectiveness of the proposed system for voltage recovery. >
15 citations
11 Jun 1990
TL;DR: In this paper, a method for efficiently analyzing distributed power systems during the design process is presented, where individual DC-DC power converters are modeled by using averaged or device-level representations.
Abstract: A method for efficiently analyzing distributed power systems during the design process is presented. Individual DC-DC power converters are modeled by using averaged or device-level representations. The averaged models for basic power converter topologies are combined with behavioral models for the control loop. Simulation accuracies close to those for a full component-level model can be achieved with more than an order-of-magnitude reduction of the simulation time. The newly developed models are used for system-level simulation. System stability for fully distributed loads is readily determined for a number of power systems configurations. >
12 citations
12 Aug 1990
TL;DR: In this paper, a comprehensive automation design for Space Station Freedom's electric power system is presented, which aims to increase station productivity by applying expert systems and conventional algorithms to automate power system operation.
Abstract: A comprehensive automation design is being developed for Space Station Freedom's electric power system. A joint effort between NASA's Office of Aeronautics and Space Technology and NASA's Office of Space Station Freedom, it strives to increase station productivity by applying expert systems and conventional algorithms to automate power system operation. An integrated approach to the power system command and control problem is defined and used to direct technology development in: diagnosis, security monitoring and analysis, battery management, and cooperative problem-solving for resource allocation. The prototype automated power system is developed using simulations and test-beds.
10 citations
TL;DR: A microcomputer-based power network control simulator designed to be used as a teaching aid for students in power engineering courses is introduced, an offline version of control systems actually used in power utilities.
Abstract: A microcomputer-based power network control simulator designed to be used as a teaching aid for students in power engineering courses is introduced. The system is an offline version of control systems actually used in power utilities. It includes functions such as steady-state security analysis and security monitoring, online load flow, and contingency analysis. Using a special feature implemented in the system called perturbation scheduling, different events can be set up to occur at different times before the simulation takes place. Also available to the user are other functions, such as short-circuit study and transient stability analysis, that are normally used for planning or study purposes. Following a detailed description of the system, software integration in an undergraduate power system operation course is illustrated, and students responses are discussed. >
9 citations
12 Aug 1990
TL;DR: A real-time AC power system simulation laboratory that has been developed at Arizona State University is described, which gives students the opportunity to witness first-hand how a large power system behaves.
Abstract: A real-time AC power system simulation laboratory that has been developed at Arizona State University is described. The laboratory gives students the opportunity to witness first-hand how a large power system behaves. It can simulate scenarios to demonstrate system disturbances of various types as well as appropriate recovery actions. Researchers also use the laboratory to study power system control methods, effects of various models and algorithms in the simulation, the effectiveness of full graphic displays, and computer communication methods. An overview is given of the computational environment, which consists of three major types of software running concurrently on two computers. The operation of the system is demonstrated for a simple scenario, i.e. relieving an overloaded transformer or line. >
04 Nov 1990
TL;DR: Preliminary results on using artificial neural networks as a dispatcher's aid for power system dynamic security assessment are presented and it is found that the ANN is able to properly estimate the postfault state and accurately predict the security status of the power system.
Abstract: Preliminary results on using artificial neural networks (ANNs) as a dispatcher's aid for power system dynamic security assessment are presented. Dynamic security assessment is explained, and a brief introduction to ANNs is given. The ANN-based dispatcher training simulator is then described, and results for a 39-bus test system are given. It is found that the ANN is able to properly estimate the postfault state and accurately predict the security status of the power system. In general, the ANN results are in close agreement with those obtained by simulation. >
01 May 1990
TL;DR: The WR algorithm is extended to a structure-preserving power system model in which the loads are retained and results in a system of differential/algebraic equations (DAEs) that is suitable for simulation by the WR method.
Abstract: Several results pertaining to the partitioning of the waveform relaxation (WR) algorithm for dynamic simulation are presented. The WR algorithm is extended to a structure-preserving power system model in which the loads are retained. This results in a system of differential/algebraic equations (DAEs). Power systems are shown to exhibit several dynamic characteristics which make them suitable for simulation by the WR method. A heuristic method for determining a fault-dependent partitioning of the power system for parallel implementation is given. >
05 Dec 1990
TL;DR: The authors present an efficient technique for solving the weekly thermal unit commitment and hydrothermal generation scheduling problem known as multi-pass dynamic programming (MPDP).
Abstract: The authors present an efficient technique for solving the weekly thermal unit commitment and hydrothermal generation scheduling problem known as multi-pass dynamic programming (MPDP). The MPDP technique can overcome the difficulties associated with the requirements of the long computation time and the large storage memory of conventional dynamic programming. The algorithm is tested on a power system with seven hydro units, one pumped storage plant, and forty thermal units. Solutions are reached within 40 min on a 16-MHz PC/AT and are consistent with engineering intuition. The reasonable results, the fast convergence, and small memory requirement make the algorithm suitable for practical systems with many generation units. >
TL;DR: In this article, the authors describe the theoretical and practical development of a personal computer-based demonstration of power generation concepts using a Y-wound generator connected to an infinite bus through a stepup transformer and two parallel lines.
Abstract: A description is given of the theoretical and practical development of a personal-computer-based demonstration of power generation concepts. The software developed simulates a Y-wound generator connected to an infinite bus through a step-up transformer and two parallel lines. The operation of the generator is simulated under starting, normal, and abnormal conditions of the power system. >
11 Jun 1990
TL;DR: In this article, the development and implementation of a static VAr (volt-ampere reactive) compensator (SVC) model for digital transient simulation packages are described, and the method of interfacing the model to a power system transients program is discussed.
Abstract: The development and implementation of a static VAr (volt-ampere reactive) compensator (SVC) model for digital transient simulation packages are described The SVC model consists of a 12-pulse thyristor controlled reactor (TCR) with a thyristor switched capacitor (TSC) The equations for the circuit are obtained in state variable form using graph theory techniques and result in accurate, numerically stable solutions The switching of the TSC capacitors has been modeled in a novel manner that saves on storage and computation time The method of interfacing the model to a power system transients program is discussed The transients program can be used to model large power systems external to the SVC model A demonstration of the use of the SVC model in a power system simulation with the EMTDC packager is presented >
01 May 1990
TL;DR: Using simple mathematical techniques, this parametric program is solved explicitly, thus providing an efficient tool for optimal looad dispatch when several levels of demand have to be met with a fixed configuration of generating units.
Abstract: The problem of optimal load dispatch (excluding unit commitment and network questions) is modeled as a parametric convex quadratic programming problem with the demand acting as parameter. Using simple mathematical techniques we solve this parametric program explicitly, thus providing an efficient tool for optimal looad dispatch when several levels of demand have to be met with a fixed configuration of generating units.
12 Aug 1990
TL;DR: In this paper, the use of a multiple pulse testing technique was proposed to determine the electrical characteristics of large megawatt level power systems, such as the Mapham inverter.
Abstract: Electric power requirements for aerospace missions have reached megawatt power levels. Within the next few decades, it is anticipated that a manned lunar base, interplanetary travel, and surface exploration of the martian surface will become reality. Several research and development projects aimed at demonstrating megawatt power level converters for space applications are currently underway at the NASA Lewis Research Center. Innovative testing techniques will be required to evaluate the components and converters, when developed, at their rated power in the absence of costly power sources, loads, and cooling systems. Facilities capable of testing these components and systems at full power are available, but their use may be cost prohibitive. This paper proposes the use of a multiple pulse testing technique to determine the electrical characteristics of large megawatt level power systems. Characterization of a Mapham inverter is made using the proposed technique and conclusions are drawn concerning its suitability as an experimental tool to evaluate megawatt level power systems.
TL;DR: For example, transient network analyzers (TNAs) as mentioned in this paper can be used to simulate a portion of a power system in miniature, complete with voltage sources representing generators and various kinds of capacitive or inductive loads.
Abstract: Electromagnetic transients are the tidal waves of electric power systems. These momentary voltage surges generally lasting only fractions of a second can be powerful enough to disrupt normal operations and even cause serious damage to major pieces of equipment, such as transformers. Created by lightning, line faults, substation switching functions, and other sudden events along a utility network, transients must be taken into account both in choosing equipment ratings for a power system and in setting its operating parameters. Like the builders of a seawall that must withstand the highest expected waves from the ocean, engineers trying to guard against damage from transients face an extraordinary design task. Most of the huge computer simulation codes related to power systems either model steady-state conditions or deal with system stability problems. The analysis of electromagnetic transients, on the other hand, requires a much more detailed examination of how some critical portion of a power system will react to conditions that can change greatly in microseconds. For many years, simulation of transient effects was performed by special-purpose analog computers called transient network analyzers (TNAs). These machines, which are still in use, recreate a portion of the power system in miniature, complete with voltage sources representing generators and various kinds of capacitive or inductive loads. TNAs are generally adequate but relatively inflexible, tedious to set up, and cumbersome to use. Once a system configuration is modeled, many simulations can be performed. Given the need to manually reconfigure TNA circuits to represent changes in a system, however, the analyzers can also be quite expensive to use. During the late 1960s, Herman Dommel of the Bonneville
TL;DR: For sophisticated approaches to system planning, development of methodologies and techniques are needed to incorporate practical knowledge of planning engineers into programs which also include the numerical analysis programs.
Abstract: Modern power systems are required to generate and supply high quality electric energy to customers. To achieve this requirement, computers have been applied to power system planning, monitoring and control. Power system application programs for analyzing system behaviours are stored in computers. In the process of generating the development and operation plans for a power system, engineers execute system analysis programs repeatedly by adjusting and modifying input data to them according to their experience and heuristic knowledge about the system until satisfactory plans are determined. However, the programs so far developed for power system analysis and planning are based on mathematical models and are implemented using languages which are suitable for numerical computation only. For sophisticated approaches to system planning, development of methodologies and techniques are needed to incorporate practical knowledge of planning engineers into programs which also include the numerical analysis programs.
28 Mar 1990
TL;DR: Work at Bath has developed from optimal control studies for a single generator, to the simulation of complex multi-machine power systems, which can be exploited by a computer system using a number of processing units.
Abstract: Work at Bath has developed from optimal control studies for a single generator, to the simulation of complex multi-machine power systems. Early work showed that power system simulation could be divided into several concurrent processes. At the highest level user interaction and graphical output can run concurrently with the main calculation model. The model itself has inherent concurrency between the individual generators. This can be exploited by a computer system using a number of processing units. Using multiple microprocessors, a power system simulator can be built with dedicated hardware giving reasonable performance at low cost.
22 Jan 1990
TL;DR: A neural network design and simulation environment for real-time fault diagnosis of a model power system and the suitability of using artificial neural networks for fault detection and diagnosis of electric power systems is explored.
Abstract: Fault detection and diagnosis in real-time are areas of research interest in knowledge-based expert systems. Rule-based and model-based approaches have been successfully applied to some domains, but are too slow to be effectively applied in a real-time environment. Neural computing is one of the fastest growing areas of artificial intelligence research. This paper explores the suitability of using artificial neural networks for fault detection and diagnosis of electric power systems. The paper describes a neural network design and simulation environment for real-time fault diagnosis of a model power system.
12 Aug 1990
TL;DR: In this article, the authors describe the results of the power system fault study and the planned implementation of these faults into the Large Autonomous Spacecraft Electrical Power System (LASEPS) Breadboard.
Abstract: NASA - Marshall Space Flight Center proposes to implement computer controlled fault injection into an electrical power system breadboard to study the reactions of the various control elements of this bread board. Elements understudy include the Remote Power Controllers (RPCs), the algorithms in the control computers, and the artificially intelligent control programs which are resident in this breadboard. To this end, a study of electrical power system faults is being performed to yield a list of the most common power system faults. The results of this study will be applied to a multi-channel high voltage dc spacecraft power system called the Large Autonomous Spacecraft Electrical Power System (LASEPS) Breadboard. This paper will describe the results of the power system fault study and the planned implementation of these faults into the LASEPS Breadboard.
05 Dec 1990
TL;DR: In this paper, the authors consider the use of a multiple controller structure in an attempt to achieve fault-tolerant control of a power system, which consists of a model reference adaptive controller in parallel with a conventional power system stabilizer.
Abstract: The authors consider the use of a multiple controller structure in an attempt to achieve fault-tolerant control of a power system. The controller consists of a model reference adaptive controller in parallel with a conventional power system stabilizer. The adaptive system is based on an adaptive controller originally developed to stabilize unknown linear systems with relative degree one or two and modified to operate in the presence of bounded disturbances and high-frequency unmodeled dynamics. System closed-loop behavior is studied via simulation in the presence of significant load induced plant uncertainty as well as failure of the conventional power system stabilizer. Significant improvement in closed-loop system behavior is noted during normal operation as well as during load peaks and conventional stabilizer failure. >
12 Aug 1990
TL;DR: In this paper, an expert system competent in the domain of cryogenic fluid management experimentation was developed to help design and test automated power scheduling software for Space Station Freedom's electric power system.
Abstract: Space Station Freedom will provide an infrastructure for space experimentation. This environment will feature regulated access to any resources required by an experiment. Automated systems are being developed to manage the electric power so that researchers can have the flexibility to modify their experiment plan for contingencies or for new opportunities. To define these flexible power management characteristics for Space Station Freedom, a simulation is required that captures the dynamic nature of space experimentation; namely, an investigator is allowed to restructure his experiment and to modify its execution. This changes the energy demands for the investigator's range of options. An expert system competent in the domain of cryogenic fluid management experimentation was developed. It will be used to help design and test automated power scheduling software for Freedom's electric power system. The expert system allows experiment planning and experiment simulation. The former evaluates experimental alternatives and offers advice on the details of the experiment's design. The latter provides a real-time simulation of the experiment replete with appropriate resource consumption.
12 Aug 1990
TL;DR: The Large Autonomous Spacecraft Electrical Power System (LASEPS) as mentioned in this paper is a complete autonomous source-to-load power system based on two breadboards developed by NASA/MSFC.
Abstract: NASA/Marshall Space Flight Center (MSFC) has developed two autonomous electrical power system breadboards. The first breadboard, the Autonomously Managed Power System (AMPS), is a two power channel system featuring energy generation and, storage and 24-kW of switchable loads all under computer control. The second breadboard, the Space Station Module/Power Management and Distribution (SSM/PMAD) testbed, is a two-bus 120-Vdc model of the space station power subsystem featuring "smart" switchgear and multiple knowledge-based control systems. NASA/MSFC is combining these two breadboards to form a complete autonomous source-to-load power system called the Large Autonomous Spacecraft Electrical Power system (LASEPS). This paper will describe the two individual systems, the combined systems (hardware and software), and the current and future uses of LASEPS.
07 Oct 1990
TL;DR: In this article, the authors discuss the language choices, computer-aided engineering and design interfaces, and standards for power system software used by electric utility industries used by power utility industries.
Abstract: The language choices, computer-aided engineering and design interfaces, and standards for power system software used by electric utility industries are discussed. The techniques used in time-current coordination studies, load flow programs, transient motor starting analyses, and transient stability modeling programs are described. Recommendations for machine models, governor models, load models, protection relay models, disturbance modeling, and industrial system studies are presented. >