Showing papers on "Power system simulation published in 1993"
TL;DR: In this paper, the authors conducted a study on the Alaskan railbelt system to examine the hydrothermal power system response after the hydroelectric power units at Bradley Lake are installed.
Abstract: Studies have been conducted on the Alaskan Railbelt System to examine the hydrothermal power system response after the hydroelectric power units at Bradley Lake are installed. The models and data for the generating units for the initial studies were not complete. Typical models were used, but their response appeared to be faster than judged by operating experience. A testing program was felt to be necessary so that accurate models could be obtained for the dynamic simulation studies. The testing method used for the combustion turbine governors, the models derived from tests, and comparison of those models with typical models are discussed. Simulation results revealed that the typical models were more optimistic. >
194 citations
TL;DR: In this paper, a theory for analyzing power system damping enhancement by application of static VAr compensators (SVCs) has been developed using the equal area criterion, where the SVC reactive power output at discrete points is determined from the power deviation on a transmission line.
Abstract: A theory for analyzing power system damping enhancement by application of static VAr compensators (SVCs) has been developed using the equal area criterion. Some fundamental issues, such as the effect of SVCs on a power system, how to control an SVC to improve system damping, and the differences between continuous and discontinuous control of SVC reactive power to achieve the maximum damping improvement, are discussed. A discontinuous SVC reactive power output at discrete points is determined from the power deviation on a transmission line. Time-domain simulations of the application of this approach to a one-machine system to increase swing oscillation damping and to a four-machine system to increase the damping of an interarea oscillation mode demonstrate that the theory and method can be applied to solve practical power system damping problems. >
193 citations
20 Jun 1993
TL;DR: In this paper, a digital hill-climbing control strategy combined with a bidirectional current mode power cell is presented that makes it possible to get a regulated bus voltage topology, suitable for space applications, by means of two converters.
Abstract: In power systems involving a load, a battery and a solar array, MPPT (maximum power point tracking) is a promising principle to extract the maximum amount of energy from the solar array and distribute it to the battery and loads. A digital hill-climbing control strategy combined with a bidirectional current mode power cell is presented that makes it possible to get a regulated bus voltage topology, suitable for space applications, by means of two converters. Theory, simulation, and breadboard validation are successively detailed. >
98 citations
TL;DR: In this article, an extended time-scale stability (EXSTAB) program is developed for representing a wide variety of power system performance problems, from transient stability through long-term dynamics and voltage instability.
Abstract: A new program, EXSTAB (extended time-scale stability) has been developed for representing a wide variety of power system performance problems, from transient stability through long-term dynamics and voltage instability. The capability of the program includes multiple execution modes and automatic step size selection to address conflicting goals of accuracy and efficiency. The modeling includes a broad range of apparatus to provide the needed time-scale representation (four orders of magnitude). Models for automatic generation control, plant characteristics and control, voltage and reactive power control, static and dynamic loads, and protective relaying for apparatus and system connections are provided. Technologies were developed to perform analysis of voltage stability and prediction of peak power transfer to avoid voltage collapse. >
74 citations
TL;DR: In this article, the optimality conditions of an incremental network flow programming (INFP) approach are described and the implementation of INFP in an energy management system (EMS) and its interface with the existing unit commitment (UC) software are presented.
Abstract: Hydrothermal coordination (HTC), consisting of hydro optimization and thermal unit commitment, is a major function in a power system for allocating its generating resources to achieve the system's maximum economy. The optimality conditions of an incremental network flow programming (INFP) approach are described. The implementation of INFP in an energy management system (EMS) and its interface with the existing unit commitment (UC) software are presented. Some new features are described in detail. The combined HTC and UC package has been delivered to a power utility, Tenaga National Berhad (TNB) in West Malaysia. Internal tests and factory acceptance tests have shown that NFP with a modified Superkilter algorithm is a powerful tool for hydro network flow optimization. >
67 citations
TL;DR: A time sequential Monte Carlo simulation approach to reliability assessment of substations and switching stations is presented in this article, which is illustrated by application to a practical configuration and used to evaluate the station reliability indices which are then compared with those obtained using an analytical method.
Abstract: A time sequential Monte Carlo simulation approach to reliability assessment of substations and switching stations is presented. The technique is illustrated by application to a practical configuration and is used to evaluate the station reliability indices which are then compared with those obtained using an analytical method. The study results show that the simulation method can provide acceptable indices. The simulation approach is also used to perform station sensitivity analysis by varying selected station component parameters. This type of analysis can play an important role in improving power system reliability, and is essential and necessary in the selection of critical components. The Monte Carlo procedure is utilized to develop probability distributions associated with the station reliability indices. It is shown how the simulation method can provide additional indices which cannot easily be obtained using an analytical method. >
55 citations
27 Sep 1993
TL;DR: The development of a fuse model for SPICE derived software that can accurately represent characteristic fuse parameters and can be adapted to represent the operation of circuit breakers is reported on.
Abstract: The design and analysis of overcurrent protection for telecommunication DC power systems can be greatly assisted by the use of a computer-aided simulation tool. This paper reports on the development of a fuse model for SPICE derived software that can accurately represent characteristic fuse parameters. The fuse model can also be adapted to represent the operation of circuit breakers. >
53 citations
TL;DR: A parallel simulated annealing (PSA) technique is developed to decompose power systems so that subsystems are equally separated in terms of the number of nodes and control variables.
Abstract: This paper proposes a parallel optimization approach to power system decomposition for voltage control. In this paper, a parallel simulated annealing (PSA) technique is developed to decompose power systems so that subsystems are equally separated in terms of the number of nodes and control variables. System decomposition is one of difficult discrete number combinatorial problems. The PSA technique provides better solutions than the conventional SA because of searching a solution near a global minimum over a wide range. The proposed method is tested in IEEE 30, 57, and 118 node systems. >
45 citations
TL;DR: An application of the automatic differentiation method which results in large savings in the computation of Jacobian matrices, which should be valuable to other power system software, in particular those which offer users the possibility of defining their own models.
Abstract: Many numerical methods used in power system simulation require the computation of Jacobian matrices. This being particularly true for implicit integration algorithms, and not for explicit ones. These computations often take a significant proportion of the overall CPU time. This paper presents an application of the automatic differentiation method which results in large savings in the computation of Jacobian matrices. An original application of this method is in a software which simulates power systems dynamics. As the program enables the users to introduce their own models, automatic differentiation becomes particularly efficient. In comparison with numerical differentiation, it leads to a saving of 80% of the time required for the computation of the Jacobian matrices and up to 28% of the total CPU time. Automatic differentiation is a very efficient method which should be valuable to other power system software, in particular those which offer users the possibility of defining their own models. >
27 citations
TL;DR: In this paper, the weekly optimization of a power system consisting of hydro and thermal units is discussed and the solution of the unit commitment and economic dispatch problem is determined over a period of a week on an hourly basis.
26 citations
08 Nov 1993
TL;DR: A genetic approach for determining the priority order in the commitment of thermal units in power generation to meet the load demand and the reverse requirement at each time interval, such that the overall system generation cost is a minimum, while satisfying various operational constraints.
Abstract: The authors present a genetic approach for determining the priority order in the commitment of thermal units in power generation. The objective of the problem is to properly schedule the on/off states of all thermal units in a system to meet the load demand and the reverse requirement at each time interval, such that the overall system generation cost is a minimum, while satisfying various operational constraints. The authors examine the feasiblity of using genetic algorithms and report some simulation results in near-optimal commitment of thermal units in a power system.
TL;DR: In this article, the purpose of the equipment described is to separate the power system when an out-of-step between two groups of generators within it is predicted, based on the generator's angular-velocity data measured by electromagnetic sensors and gears that are fastened directly to the rotors.
Abstract: The purpose of the equipment described is to separate the power system when an out-of-step between two groups of generators within it is predicted. The out-of-step prediction method is based on the generator's angular-velocity data measured by electromagnetic sensors and gears that are fastened directly to the rotors. The equipment was tested by the large-scale power system simulator APSA (Advanced Power System Analyzer) and was also field tested. The results are presented. >
02 Oct 1993
TL;DR: In this paper, an instance of poorly damped oscillations in computer simulation has been observed in the connection of an industrial cogeneration power system to the utility grid, and an extensive investigation of this problem is presented.
Abstract: An instance of poorly damped oscillations in computer simulation has been observed in the connection of an industrial cogeneration power system to the utility grid. An extensive investigation of this problem is presented. Both time-domain and frequency-domain analyses are used to determine the fundamental characteristics of the system, the major factor of the system oscillation, and a possible solution for the problem. Study results indicate that installation of a PSS (power system stabilizer) may improve the dynamic stability problems of the system. However, it requires accurate system information in the design stage and on-site field tuning after installation. Retuning services are required if the system configuration and/or generation conditions are changed dramatically. Several examples have shown the PSS did not reach its expected performance due to the inaccurate system parameters that were used to determine the parameters of the PSS. Therefore, more system operation information is desired before installation of a PSS. >
05 Sep 1993
TL;DR: The authors describe the detail of their developed digital/analog conversion interface of the real-time digital simulator for testing advanced power instruments and its conversion algorithm, the system configuration of the simulator with the interface, and experimental results are presented.
Abstract: The need for real-time simulation stems from the fact that in many practical situations it is desirable to analyze the dynamic behavior of a large power system with advanced equipment that has complex and high-speed performance. Analog simulators are effective, however they impose serious limitations on the size of the system that is being modeled. The authors have studied and developed a real-time digital simulator using a hypercube computer, and realized a real-time performance available for the analysis of large power systems. Now as the second step of their study, they developed a digital/analog conversion interface for testing actual power instruments. The interface exchanges the variables of fundamental frequency domain in the real-time digital simulator, and the variables of exact time domain in the analog equipment connected to the simulator. In this paper, the authors describe the detail of their developed digital/analog conversion interface of the real-time digital simulator for testing advanced power instruments. Its conversion algorithm, the system configuration of the simulator with the interface, and experimental results are also presented. >
19 Apr 1993
TL;DR: In this paper, the authors simulated the fault with the EMTP and obtained a satisfying simulation result which was almost the same as the practical record, and the over voltage protection system operated normally and the VSPS continued as normal.
Abstract: The world's-first power converter-fed variable speed pumped storage power system (VSPS) was commissioned in 1990. The VSPS has been monitored to verify the operating characteristics when a fault occurs in the electric power system. A one-line fault occurred in the transmission line in 1992. The over voltage protection system operated normally and the VSPS continued as normal. The authors simulated the fault with the EMTP and obtained a satisfying simulation result which was almost the same as the practical record. >
20 Jun 1993
TL;DR: In this article, a new compound energy converter for low earth orbit satellites is proposed, using the parallel power conversion technique, a new maximum power point tracking technique based on positive feedback, and the peak current-programmed control technique.
Abstract: A new compound energy converter for low earth orbit satellites is proposed, using the parallel power conversion technique, a new maximum power point tracking technique based on positive feedback, and the peak current-programmed control technique. These techniques are used for low EMI (electromagnetic interference), high power conversion efficiency, high reliability, stability and size reduction. >
02 Oct 1993
TL;DR: In this paper, a reliability analysis method that combines a Monte Carlo simulation with an electrical network is presented, which considers short circuits followed by an intervention of the protection instead of just the removal of a component.
Abstract: A reliability analysis method that combines a Monte Carlo simulation with an electrical network is presented. The method considers short circuits followed by an intervention of the protection instead of just the removal of a component. The correct and incorrect behavior of the protection can be modeled in detail. The method is suitable for industrial power systems with sensitive loads. The method can be used to compare the reliability of the supply for different design alternatives, to quantify the gain that can be obtained by increasing the voltage solidity of a plant, and to choose a maintenance policy. The author presents an overview of the power system model used and discusses the interruption criterion, the protection model, and the aging of components. For an example network the influence of voltage solidity and maintenance is discussed. >
TL;DR: In this paper, a hybrid algorithm which combines the two methods, selecting their best features, is described, and the relative performances of conventional and hybrid algorithms are discussed, showing that the hybrid representation provides more stable, accurate and efficient solutions.
Abstract: The two methods in current use for the transient simulation of high-voltage DC (HVDC) power systems are electromagnetic transient programs and state variable analysis. A hybrid algorithm which combines the two methods, selecting their best features, is described. The relative performances of conventional and hybrid algorithms are discussed. Simulation results of typical back-to-back HVDC links show that the hybrid representation provides more stable, accurate and efficient solutions. >
Proceedings Article•
01 Jun 1993
TL;DR: The paper examines the feasibility of using genetic algorithms for determining short-term commitment order of thermal units in studied power systems, and reports preliminary results in determining a near-optimal commitment order.
Abstract: Unit commitment is a complex decision-making process because of multiple constraints which must not be violated while nding the optimal or a near-optimal commitment schedule. This paper discusses the application of genetic algorithms for determining short-term commitment of thermal units in power generation. The objective of the optimal commitment is to determine the on/oo states of the units in the system to meet the load demand and spinning-reserve requirement at each time period such that the overall cost of generation is minimum, while satisfying various operational constraints. The paper examines the feasibility of using genetic algorithms, and reports preliminary results in determining a near-optimal commitment order of thermal units in studied power systems.
TL;DR: In this article, fast and slow power system dynamic performance is illustrated with two examples from actual electric utility systems, chosen to characterize a local reactive power shortage and radial system performance, respectively.
Abstract: Fast and slow power system dynamic performance is illustrated with two examples from actual electric utility systems. These examples were chosen to characterize a local reactive power shortage and radial system performance, respectively. In both cases, a critical disturbance is examined. These disturbances result in a load flow that cannot be solved. Studies were performed with the Extended Term Dynamics module of PTI's Power System Simulation (PSS/E) program. >
05 Sep 1993
TL;DR: In this article, the authors presented a detailed model of the Nelson River HVDC System's Bipole 1 controls for use with the RTDS (Real-Time Qigital Simulator).
Abstract: A fully digital, electromagnetic transients class of power systems simulator capable of continuous real-time operation has been developed at the Manitoba HVDC Research Centre. A detailed model of the Nelson River HVDC System’s Bipole 1 controls was prepared for use with the RTDS (Real-Time Qigital Simulator). Operation of the RTDS using the modelled I-NDC controls, as well as using physical controls interfaced to the simulator is presented herein.
06 Oct 1993
TL;DR: The possibility of the use of the existing Dae solvers to solve the transient stability analyse's application is discussed and the research in developing a scalable, parallel DAE solver for use by the power system community and in related applications is discussed.
Abstract: Real-time or faster-than-real-time power system transient stability simulations will have significant impact on the future design and operations of both individual electrical utility companies and large interconnected power systems. The analysis involves solution of extremely large systems of differential and algebraic equations. Differential-Algebraic Equation (DAE) solvers have been used to solve problems similar in nature to the transient stability analysis (TSA) problem. This paper discusses the possibility of the use of the existing DAE solvers to solve the transient stability analyse's application. We also discuss our research in developing a scalable, parallel DAE solver for use by the power system community and in related applications. >
TL;DR: In this paper, the authors describe test results from simulation studies and field tests where a self-tuning control algorithm was tested using a digital power system stabilizer and indicated a marked improvement in local mode damping and a contribution to damping at the inter-area mode while initial tests at power plants gave promising results.
Abstract: Digital power system stabilizers have opened new avenues for applying innovative control strategies to damp generator rotor oscillations at steam and hydroelectric power plants. This paper describes test results from simulation studies and field tests where a self-tuning control algorithm was tested using a digital stabilizer. The simulation studies indicated a marked improvement in local mode damping and a contribution to damping at the inter-area mode while initial tests at power plants gave promising results. >
07 Mar 1993
TL;DR: The authors discuss how object-oriented programming techniques can be applied to the development of power-engineering-related software and use segments of code used in a three-phase load flow program as examples.
Abstract: The authors describe the object-oriented approach, which is currently being touted as a means of making programmers more productive but will require new approaches to viewing old problems. They discuss how object-oriented programming techniques can be applied to the development of power-engineering-related software. Segments of code that were used in a three-phase load flow program are used as examples.
Book•
01 Jan 1993
TL;DR: In this paper, the authors present a state-of-the-art of mathematical programming methodologies, unit commitment, optimal power flow and their applications in power system control, and present several optimization packages currently used for unit commitment and power flow calculations.
Abstract: Permanently increasing requirements in power supply necessitate efficient control of electric power systems. An emerging subject of importance is optimization. Papers on modelling aspects of unit commitment and optimal power flow provide the introduction to power systems control and to its associated problem statement. Due to the nature of the underlying optimization problems recent developments in advanced and well established mathematical programming methodologies are presented, illustrating in which way dynamic, separable, continuous and stochastic features might be exploited. In completing the various methodologies a number of presentations have stated experiences with optimization packages currently used for unit commitment and optimal power flow calculations. This work represents a state-of-the-art of mathematical programming methodologies, unit commitment, optimal power flow and their applications in power system control.
TL;DR: In this article, a multi-pass dynamic programming (MPDP) combined with successive approximations is applied to solve the weekly thermal unit commitment and hydrothermal generation scheduling problem.
Abstract: This paper applies a very efficient new technique, multi‐pass dynamic programming (MPDP) combined with successive approximations, to solve the weekly thermal unit commitment and hydrothermal generation scheduling problem. Conceptually, dynamic programming is suited for solving this problem, but the long computing time and the large storage memory required become unacceptable for large power systems and long scheduling periods. The MPDP technique can overcome these difficulties. Furthermore, the unit start‐up cost and pumped storage plants are considered in the hydrothermal coordination instead of only the production cost as in the previous application. The algorithm is tested on Taipower system with forty thermal units, seven conventional hydro units and one pumped storage plant. The results show that this method is suitable for practical systems.
19 Oct 1993
TL;DR: The application of a fuzzy controller to improve the stability of power systems is presented and shows that it is very effective and gives better performance than the conventional power system stabilizer.
Abstract: The application of a fuzzy controller to improve the stability of power systems is presented in this paper. To achieve good damping characteristics over a wide range of operating conditions, speed deviation and acceleration of a synchronous generator are chosen as the input signals to the fuzzy controller. The stabilizing signal is determined according to the nonlinear fuzzy membership function depending on the speed and acceleration states of the generator. Simulation and implementation studies have been carried out on a one-machine and two-machine infinite bus system respectively. The simulation and implementation result show that the proposed fuzzy controller is very effective and gives better performance than the conventional power system stabilizer. >
19 Oct 1993
TL;DR: In this article, the authors compared field tests to obtain the parameters of the power system elements and validate the models and their parameters with emphasis on the comparison of test and simulation results, and showed that the dynamic characteristics of power systems can be more exactly represented by using the models obtained from field test data.
Abstract: Mathematical models of power system elements are fundamental to power system studies such as planning, design, operation and control. It is necessary to improve the accuracy of power system simulation by means of identification techniques to obtain more realistic parameters of the elements in real power systems. In this paper, field tests to obtain the parameters and field tests to validate the models and their parameters are briefly described with emphasis on the comparison of test and simulation results. Transient stability studies show that the dynamic characteristics of power systems can be more exactly represented by using the models and parameters obtained from field test data. They also show that the total power output of the concerned power plant can be increased by 4-6 percent. Thus the economic benefit is considerable. >
01 Mar 1993
TL;DR: The authors demonstrate that shallow reasoning systems performing a comparative analysis of the data are sufficient for a complex application.
Abstract: Model-based artificial intelligence approaches to diagnosis require encoding a reasonable facsimile of the problem domain. The model is encoded as a classical engineering simulation of the domain, a spacecraft electrical power system (EPS). Portions of the reasoning system thus become comparators between the expected behavior and the EPS. The diagnostic problem is partitioned into six discrete steps including: fault detection, diagnosis and hypothesis generation, hypothesis space pruning, validation of the hypothesis, test case selection, and verification of the diagnosis. The system performs a simplified form of learning by injecting diagnosed faults into the model thereby maintaining its consistency with the EPS and reducing unnecessary future computations. The authors demonstrate that shallow reasoning systems performing a comparative analysis of the data are sufficient for a complex application. >