Showing papers on "Power-flow study published in 1979"
TL;DR: In this paper, the authors describe the development and evaluation of an analytical method for the direct determination of transient stability, which is based on the analysis of transient energy and accounts for the nature of the system disturbance as well as for the effects of transfer conductances on systenmbehavior.
Abstract: This paper describes the development and evaluation of an analytical method for the direct determination of transient stability. The method developed is based on the analysis of transient energy and accounts for the nature of the system disturbance as well as for the effects of transfer conductances onsystenmbehavior. It has been evaluated on a 10 generator 39 bus system and on a 20 generator 118 bus system. The method predicts critical clearing times for first swing transient stability which agree very closely with the results of simulations.
929 citations
TL;DR: A linear programming method for security dispatch and emergency control calculations on large power systems is presented, which works directly with the normal power-system variables and limits, and incorporates the usual sparse matrix techniques.
Abstract: A linear programming (LP) method for security dispatch and emergency control calculations on large power systems is presented. The method is reliable, fast, flexible, easy to program, and requires little computer storage. It works directly with the normal power-system variables and limits, and incorporates the usual sparse matrix techniques. An important feature of the method is that it handles multi-segment generator cost curves neatly and efficiently.
396 citations
TL;DR: The main contribution is a simple extension to the Ward-type equivalencing method that solves the boundary-bus designation problem and gives reliable and accurate results.
Abstract: Equivalent models for the external system in online load-flow studies are presented. The main contribution is a simple extension to the Ward-type equivalencing method that solves the boundary-bus designation problem and gives reliable and accurate results. The method can be applied equally well for off-line equivalencing, where it overcomes the need for buffer zones. Variations on this technique are investigated. The models require topology information, but no real-time measurement data, for the external system. The new methods have been verified by simulation on the IEEE 30 and 118 bus load-flow test systems and on the 835-bus interconnected 15 GW power system of S.E. Brazil.
139 citations
Book•
01 Jan 1979
TL;DR: In this paper, the authors present a power system representation of the power flow problem and present a fault analysis method for the power system with respect to balanced and unbalanced faults, as well as dynamic performance of power systems.
Abstract: Sinusoidal Steady State Circuit Concepts. Power System Representation. Transmission Lines. The Power Transformer. The Synchronous Machines. The Power Flow Problem. Operation and Control of Power Systems. Balanced and Unbalanced Faults. Fault Analysis by Computer Methods. Power System Protection. Power System Dynamic Performance. Appendices. Index.
120 citations
15 May 1979
TL;DR: The paper attempts to provide some clarification of the main fundamental analytical and computational, issues involved in the design of an LP-based method for the rescheduling of power-system operation.
Abstract: Linear and related programming methods have application in transmission planning, security dispatch and emergency control of power systems. With a large still-growing body of literature on the subject, this paper offers a short review of the available LP approaches, techniques and formulations, with due emphasis on state-of-the-art versions. The differences between primal and dual methods and sparse and nonsparse formulations are exposed, and various important techniques such as relaxation, upper bounding and separable programming are dealt with. Thus the paper attempts to provide some clarification of the main fundamental analytical and computational, issues involved in the design of an LP-based method for the rescheduling of power-system operation.
107 citations
TL;DR: In this article, an extension of the power transfer capacity calculation to the calculation of maximum power system loading is described. But the authors focus on the application to assessment of network adequacy and long range planning.
Abstract: This paper describes an extension of the power transfer capacity calculation to the calculation of maximum power system loading. This loading capability is a function of the generation and transmission capacity of the power system. The dc power flow equations provide a basis for the development of constraint equations necessary in the linear programming optimization of the generation-transmission system. An example is provided to illustrate the concepts of the load supplying capability of the power system, and the application to assessment of network adequacy and long range planning is discussed.
75 citations
TL;DR: The enhancement of this data base through advanced estimation programs for the states and parameters of the network is considered and the role of such programs and the different forms they take are presented in a comprehensive and unified manner.
Abstract: The operation of large-scale power systems demands that the real-time monitoring, security, and control procedures can draw on a consistent and reliable set of data representing the measurements and the network parameters. This paper considers the enhancement of this data base through advanced estimation programs for the states and parameters of the network. The role of such programs and the different forms they can take are presented in a comprehensive and unified manner. This will assist the designer in the task of selection and development of a suitable algorithm for his system from a set of possible approaches.
41 citations
Patent•
09 Aug 1979
TL;DR: In this article, a system for electronically metering an A.C. electrical power system to derive performance parameters such as real and reactive power useful in revenue metering and fault protection applications is presented.
Abstract: A system for electronically metering an A.C. electrical power system to derive performance parameters such as real and reactive power useful in revenue metering and fault protection applications. Voltage and current sensors associated with the power system provide isolated output signals proportional to the voltage and current in the system. From these signals finite-duration impulse-response filters periodically determine Walsh function correlation coefficients by integrating the voltage and current signals at least once during each period of the power system and periodically sampling and holding the integrated signal in sequence with the integration. The present and a plurality of immediately preceding correlation coefficient values are stored in memory, and by combination of the correlation coefficients by addition, subtraction or multiplication, power system performance parameters, such as real power, reactive power, voltage, current, or power factor, are obtained for utilization in revenue metering or overload protection applications. Related methods are also disclosed.
36 citations
TL;DR: In this article, an external system equivalent for on-line generator outage simulation is presented. The proposed method is an extension to the Ward equivalent, which models the steady state MW response of the external system after primary speed control actions.
Abstract: This paper describes an external system equivalent for on-line generator outage simulation. The equivalent models the steady- state MW response of the external system after primary speed control actions. The proposed method is an extension to the Ward equivalent. Starting with the frequency response characteristics of the individual units and loads in the external system, equivalent frequency response characteristics for each boundary bus have been developed. These equivalent frequency response characteristics model not only the total in-rush, but also the distribution among the individual tie lines. In addition to the data required for branch outage simulations the incremental speed regulations and rated powers of all external units on the line are assumed to be known. No real-time measurement data from the external control areas are required. The suggested equivalent has been verified by off-line simulations of 10 severe generator outages in three European 380/220 kV networks.
32 citations
TL;DR: An efficient and reliable algorithm is developed for studying the load shedding and generation reallocation problem in emergencies where a major portion of the transmission system is disabled and an a.c. power flow solution cannot be found for the over- loaded system.
Abstract: An efficient and reliable algorithm is developed for studying the load shedding and generation reallocation problem in emergencies where a major portion of the transmission system is disabled and an a.c. power flow solution cannot be found for the over- loaded system. The problem is first formulated as a nonlinear optimization problem, and an approximation based on a linear sensitivity between real injections and voltage angles is derived. The linearized problem is solved by a linear programming algorithm which exploits the sparsity of the linear programming tableau. The sparse linear programming algorithm is described, and the test result on a 37-node system shown. The solution algorithm is applicable for large networks.
32 citations
TL;DR: In this article, a power system stabilizer application overcomes an unusual combination of constraints which would otherwise severely limit the damping influence obtainable from a conventional stabilizer system, by modifying a specific technique.
Abstract: This power system stabilizer application overcomes an unusual combination of constraints which would otherwise severely limit the damping influence obtainable from a conventional stabilizer system. A specific technique of modifying the stabilizer system has been applied effectively in a two unit steam power plant and its effectiveness has been verified by system tests. This modified technique would be applicable in other plants to relieve such constraints.
TL;DR: In this paper, the authors model the large power system DYNAMICS as one large electric machine so that both the voltage and the frequency of the unknown power system bus may vary.
Abstract: Instead of approximating an unknown large power system in the neighboring area by an infinite bus of constant voltage and constant frequency, this paper models the large power system DYNAMICS as one large electric machine so that both the voltage and the frequency of the unknown power system bus may vary. For the parameter estimation, an unknown dynamic power system model is developed, and a local power system model is adapted to accommodate these changes. An estimation technique is applied and an alogrithm is presented. Computer results show that the unknown large power system parameters can be uniquely determined regardless of the power factor of the local system, the local load, a strong or weak intertie, the unknown system inertia and damping, and the initial guess for the estimation.
15 May 1979
TL;DR: The particular array processor which was studied performs network solutions several times faster than general purpose large mainframe digital computers and is available at a fraction of the cost.
Abstract: The application of an array processor to solution of power system network equations is discussed and results from its performance evaluation are presented. The particular array processor which was studied performs network solutions several times faster than general purpose large mainframe digital computers and is available at a fraction of the cost. It has an immediate application for decreasing the computer costs and improving the responsiveness of programs which are used in power system planning and operations.
TL;DR: In this paper, a time-scale separation procedure is applied to a three machine interconnected power system with flux and voltage regulator dynamics, where partial models such as the electromechanical model and single machine-infinite bus model are used to identify the slow and the fast states of the systems.
01 Dec 1979
TL;DR: In this paper, the authors describe the application of decentralized tuning regulators to solve the load and frequency control problem (automatic generation control problem) of a large power system consisting of three interconnected areas with nine synchronous machines.
Abstract: This paper describes the application of decentralized tuning regulators [1] to solve the load and frequency control problem (automatic generation control problem) of a large power system consisting of three interconnected areas with nine synchronous machines. In this problem, it is assumed that the power system is completely unknown, i.e. it is assumed that a mathematical model describing the power system is not available, and it is desired to find a robust decentralized controller for the power system so that the power flow and frequency of the system are regulated, independent of any constant disturbances (load changes) which may affect the system. It is shown that the resultant control system obtained by using decentralized tuning regulator theory is in fact virtually identical to the controller obtained assuming a full knowledge of the mathematical model describing the system. This in turn implies that the conventional way of solving the load and frequency control problem is not likely to be significantly improved on by assuming that a detailed mathematical description of the power system is available or by using more complex controllers.
Book•
01 Jan 1979
TL;DR: In this paper, the authors present a textbook for electrical power or electrical generators and motors courses, which provides a broad overview of the subject, including power production, distribution, and power conversion.
Abstract: This volume is a textbook for an electrical power or electrical generators and motors course, provides a broad overview of the subject. Contents, abridged: Power production. Power distribution. Power control systems. Power conversion. Power measurement. Index.
Patent•
10 May 1979
TL;DR: In this paper, the authors proposed a scheme to transfer power from an auxiliary system to the motor bus when the phase difference of the auxiliary system with respect to the frequency of the residual voltage on the motor buses is essentially zero degrees.
Abstract: In a typical power system, a motor bus is fed by a main power system; and, an auxiliary system is provided to alternatively feed the motor bus. When a fast transfer from the main power to the auxiliary power system is desired, for example, in case of fault occurring in the main system, the inventive method transfers power in a synchronous mode; that is, power is transferred from the auxiliary system to the motor bus when the phase difference of the auxiliary system with respect to the frequency of the residual voltage on the motor bus is essentially zero degrees.
15 May 1979
TL;DR: In this paper, an estimation process is proposed which gives a much tighter estimate of the area load excess (ALE) over the scheduled load than the traditional area control error (ACE), while it also provides an extrapolated estimation of the turbine power at each unit.
Abstract: The economic dispatch and load frequency control problem is approached as a design for digital computer control with system theoretic foundations from scratch but utilizes the ingenious insights of the past 30 years of practice. In Part I of the paper, an estimation process is proposed which gives a much tighter estimate of the area load excess (ALE) over the scheduled load than the traditional area control error (ACE) while it also provides an extrapolated es- timate into the future and an estimate of the turbine power at each unit. The latter is needed for unit control. Part II** introduces a three step algorithm to generate extrapolated target curves for the individual units to follow for economically matching the area load demand throughout the day.
TL;DR: In this paper, a power system consisting of two control areas is simulated in which the two areas are interconnected via two parallel ac tie lines and as an alternative, the Interconnection via an ac line and a parallel dc link is examined.
Abstract: A power system consisting of two control areas is simulated in this paper. The two areas are interconnected via two parallel ac tie lines and as an alternative, the Interconnection via an ac line and a parallel dc link is examined. The two system configurations are subjected to the same disturbances and faults and their responses are compared and assessed with regard to system stability.
15 May 1979
TL;DR: This paper examines the possibility of using a dedicated multiprocessor network to do the step-by-step computations needed in the digital simulation of the dynamic response of a large power system.
Abstract: This paper examines the possibility of using a dedicated multiprocessor network to do the step-by-step computations needed in the digital simulation of the dynamic response of a large power system. This multiprocessor network would use a general purpose digital computer for the input and output. It is found that over 97% of the computations for a typical 1723-bus, 396-machine, stability study could be done in parallel. Approximately 30% of the computation time is spent solving the network equations, I = YE. Various algorithms for this part of the solution and ways of scheduling the work assignments to the processors are discussed.
TL;DR: In this article, a multisolution problem in power flow analysis was discussed and a solution mode concept, each mode corresponding to a solution, was introduced, and an algorithm was proposed to derive the solutions of power equations corresponding to an arbitrarily specified solution mode.
Abstract: A method for analyzing the multisolution problem in power flow analysis was discussed. The solution mode concept, each mode corresponding to a solution, was introduced. An algorithm was proposed to derive the solutions of power equations corresponding to an arbitrarily specified solution mode. The method was applied to 3, 5 and 11-node model systems with very satisfactory results. It was stated that the method would be available for finding a certain solution mode whose operating condition might bring the power system into the state of voltage collapse.
15 May 1979
TL;DR: In this article, the authors present on-line computer software and systems which were used to allow Power System Control Centre Operators to monitor and control such a stability constrained Power System, which is highly constrained by stability considerations, generator rejection schemes and security standards.
Abstract: Operation of a Power System which is highly constrained by stability considerations, generator rejection schemes and security standards requires complex control and operating strategies. This paper presents on-line computer software and systems which were used to allow Power System Control Centre Operators to monitor and control such a stability constrained Power System.
15 May 1979
TL;DR: In this paper, a digital computer program that employs a novel, fast and efficient technique to solve transient stability problems of large scale power systems is presented, which has the unique features of simulating generalized HVDC schemes; and different types of static reactive power compensators, as well as other conventional components in a power system.
Abstract: This paper presents a digital computer program that employs a novel, fast and efficient technique to solve transient stability problems of large scale power systems. The program has the unique features of simulating generalized (two and multi-terminal) HVDC schemes; and different types of static reactive power compensators, as well as other conventional components in a power system. Results for a complex ac/dc multimachine system under low short circuit ratio conditions are presented.
15 May 1979
TL;DR: The requirements and design of the input- output processing of an on-line steady state contingency analysis program for a power system control center and the violation of equipment limits indicated by the program are tracked over time by using an equipment violation matrix.
Abstract: The requirements and design of the input- output processing of an on-line steady state contingency analysis program for a power system control center are outlined in this paper. A method is described to accommodate the secondary changes in the power system configuration that may be caused by the input contingencies that have to be studied by this program. The scheme utilizes a technique to quickly detect contingencies that produce secondary changes, the presence of which requires the use of the topology processor before solving for the power flows. The output processing consists mainly of ranking the output data so that only a reasonable amount of information has to be displayed to the operator. In addition, the violation of equipment limits indicated by the program are tracked over time by using an equipment violation matrix which can be stored very efficiently using several different techniques.
15 May 1979
TL;DR: The convenient features of the Continuous Systems Modeling Program (CSMP III) in developing of three-phase power system dynamic performance are presented and a modified large resistor interface between the synchronous generator and the network is developed.
Abstract: This paper presents the convenient features of the Continuous Systems Modeling Program (CSMP III) in developing of three-phase power system dynamic performance A modified large resistor interface between the synchronous generator and the network is developed A method of computing the initial conditions of the machie including the more common situation of unbalanced conditions at the generator terminals is suggested The necessary mathematical models of the synchronous generator and the various power system network components are provided for completness Examples of load rejection and single-pole switching applications are included to demonstrate the simulation capabilities using CSMP III
01 Dec 1979
TL;DR: In this paper, the voltage dependencies of individual load elements are algebraically aggregated into a voltage dependent admittance matrix which describes the interconnected loads explicitly in terms of the voltages at the reference nodes.
Abstract: The electrical power system loads, as seen from a substation level, consist of numerous load elements and network elements. A subsystem consisting of load elements which are interconnected by network elements is connected to the rest of the power system at several points called reference nodes. This paper is concerned with a description of interconnected loads for a study of their interactions with the rest of the system through the reference nodes. The voltages at the reference nodes are the electrical inputs to the interconnected loads. Only balanced phase operations of symmetrical three phase loads are considered. The voltage dependencies of individual load elements are algebraically aggregated into a voltage dependent admittance matrix which describes the interconnected loads explicitly in terms of the voltages at the reference nodes.
01 Dec 1979
TL;DR: A new exact diakoptical technique for load-flow solution of very large power systems, using the bus admittance matrix, is developed that produces the same final result, retains the convergence property of the original untorn system, and can be applied to systems of any voltage level.
Abstract: A new exact diakoptical technique for load-flow solution of very large power systems, using the bus admittance matrix, is developed. This method employs bifactorisation and other sparsity techniques. It produces the same final result, retains the convergence property of the original untorn system, and can be applied to systems of any voltage level.