Showing papers on "Power-flow study published in 1971"
TL;DR: In this paper, an analytical approch to the construction of power system dynamic equivalents for use in stability calculations and dynamic simulations is presented, which is capable of accurately representing the dynanlical effects of generator field and amortisseur windings, voltage regulators, and speed governors.
Abstract: This paper presents an analytical approch to the construction of power system dynamic equivalents for use in stability calculations and dynamic simulations. The method presented is capable of accurately representing the dynanlical effects of generator field and amortisseur windings, voltage regulators, and speed governors. Experimental evaluation of equivalents constructed by this method is reported in a companion paper.
153 citations
TL;DR: In this article, a comparison is made of a lower-order linear model and a high-order non-linear system modelled as a single machine-infinite bus as well as multi-machine systems.
Abstract: The stabilization of power systems with excitation control using speed or power signals has been very well developed,1-6 while the application of optimal control to power system stability study is relatively new.7 Both are based on linear models. In this paper, a comparison is made of these two techniques. Signals derived from a lower order linear model are tested on a high order non-linear system modelled as a single machine-infinite bus as well as multi-machine systems.
112 citations
TL;DR: In this paper, it is shown that the classical direct methods, which are based on energy considerations, can be derived and generalized by means of Lyapunov's second method.
Abstract: This paper deals with recent advances in developing direct methods for studying the transient stability problem of single-machine and multimachine power systems. The paper starts out with the construction of the mathematical model that is usually employed in the analyis of power system transient stability. Computer simulation methods are then briefly discussed, and it is indicated why accurate direct methods for transient stability investigations would be most welcome. It is shown that the classical direct methods, which are based on energy considerations, can be derived and generalized by means of Lyapunov's second method. The main purpose of the paper is to give an exposition of the interesting results that have been obtained by applying Lyapunov's second method to the transient stability problem of single-machine and multimachine power systems. In the final portion of the paper some areas for further research are discussed.
103 citations
TL;DR: The paper develops a-method of determining the minimum amount of reactive power capacity installation required to satisfy constrained system voltage conditions, and linear programming is used to obtain the solution.
Abstract: The paper develops a-method of determining the minimum amount of reactive power capacity installation required to satisfy constrained system voltage conditions. The solution gives both location and amount of reactive sources. Sensitivity parameters are the basis of the model, and linear programming is used to obtain the solution. The method is practical and static operating constraints are naturally included. Numerical examples illustrate the application of the method.
87 citations
TL;DR: A new method of scheduling thermal generating units to achieve minimum operating costs including both running and start-up costs while at the same time maintaining a desired level of system security is described.
Abstract: The paper describes a new method of scheduling thermal generating units to achieve minimum operating costs including both running and start-up costs while at the same time maintaining a desired level of system security.
80 citations
TL;DR: In this paper, a three-state reliability model was proposed to simulate the states of power systems during faults, and the effects of component maintenance on the outage frequency and duration of a small 115-kV network were calculated.
Abstract: A reliability model is described which more closely simulates the states of power systems during faults than do the usual "two-state" models. This is achieved primarily by modelling the effects of comnponent failures on the system through three-state cycles, which include a state following the fault and another after the failed device is isolated, through switching, for repair. The effects of component maintenance are also incorporated. A sample study is presented, wherein the average outage frequency and duration of a small 115-kV network are calculated. The findings include the observations that, in most cases, the effects of all but the lowest contingency system failures can be neglected; and that coincidences of failures and maintenance are often more frequent causes of system outages than coincidences of faults.
42 citations
TL;DR: In this article, a computational procedure for the on-line optimal rescheduling of power generation is presented, which is used to correct an unreliable system operating state and bring a potentially dangerous condition into a secure operating state.
Abstract: This paper presents a computational procedurer for the on-line optimal rescheduling of power generation. Rescheduling is used to correct an unreliable system operating state and bring a potentially dangerous condition into a secure operating state. Sensitivity parameters are the basis of the model, and linear programming formulation is developed to solve the optimal rescheduling problem. The constraints on the variables are naturally included in this practical method. A small power-network illustrates the application of the method.
41 citations
TL;DR: A technique is developed for the optimum scheduling of real and reactive generation in which all the transmission network constraints are met and the feasibility of the technique is demonstrated by means of sample systems.
Abstract: A technique is developed for the optimum scheduling of real and reactive generation in which all the transmission network constraints are met. The procedure which is used utilizes a load-flow solution to satisfy the system power equations. The real and reactive schedules of the swing bus are treated as dependent variables in the optimization portion of the solution method. Inequality constraints are met as limits on the variables in the load-flow portion of the solution. The feasibility of the technique is demonstrated by means of sample systems.
36 citations
TL;DR: In this paper, the authors developed methods to obtain simplified models of the systems based on the speed of response of the variables or the modes of a power system, which can be used for dynamic stability analysis of large interconnected power systems.
Abstract: Dynamic stability analysis of a large interconnected power system is extremely time consuming and laborious and may even exceed the storage capacity of modem fast computers because of the high order of the A matrix. Hence methods have been developed here to obtain simplified models of the systems based on the speed of response of the variables or the modes.
36 citations
TL;DR: In this article, a frequency and duration approach to interconnected system reliability evaluation is presented. Butler et al. extended the basic concepts presented by Halperin and Adler and extended them to extend them to the case of two or more systems.
Abstract: Equations for computing the frequency and duration of various capacity outages were first given by Halperin and Adler1. The application to the generation area was subsequently extended by the publication of a recent series of papers2-6 which presented a far more general approach to the problem. The general method is extremely powerful and can be applied to a wide range of problems7-9. This paper utilizes the basic concepts previously presented2,3 and extends them to develop a frequency and duration approach to interconnected system reliability evaluation. Equations are developed for one system connected to another system and are subsequently extended to the case of a system connected to two or more systems. The application of the theoretical technique is illustrated in Part II of this paper entitled "System Applications".
36 citations
TL;DR: A method for the automatic optimized sectionalization of power transmission networks as required for the application of piecewise solution techniques using the minimization of the total computer core memory requirement for storage of the network impedance or admittance matrices is described.
Abstract: This paper describes a method for the automatic optimized sectionalization of power transmission networks as required for the application of piecewise solution techniques. The optimality criterion is the minimization of the total computer core memory requirement for storage of the network impedance or admittance matrices.
TL;DR: The trend in turbine-generator characteristics as unit sizes become larger is in an adverse direction from the standpoint of power system stability as discussed by the authors, and the effectiveness of independent pole switching and other control measures available to the system planner are shown.
Abstract: The trend in turbine-generator characteristics as unit sizes become larger is in an adverse direction from the standpoint of power system stability. Results of specific studies as well as a general rule of thumb for evaluating this effect are given. The effectiveness of independent pole switching and other control measures available to the system planner are shown.
TL;DR: In this paper, a unified treatment of optimum switching is presented by considering the switching instants to be elements of a generalized control vector, and dynamic optimization is then applied to determine optimum switch instants.
Abstract: Power system stability can be improved by sudden changes in the electric power network such as the insertion of braking resistors, generator dropping or load shedding A unified treatment of optimum switching is presented by considering the switching instants to be elements of a generalized control vector Dynamic optimization is then applied to determine optimum switching instants
TL;DR: In this article, a method based on linear models, discrete variable and selective iteration techniques is presented to determine the minimum most efficient combination of location and amount of static capacitors to bring the voltage level of each bus in the system above a specified minimum.
Abstract: Use of capacitor banks for voltage correction has been common practice in electric utilities for many years. Selecting the location and size of such banks for large, interconnected systems is a complicated problem because many combinations are possible. This paper presents a method based on linear models, discrete variable and selective iteration techniques that determines the minimum most efficient combination of location and amount of static capacitors to bring the voltage level of each bus in the system above a specified minimum.
TL;DR: In this paper, the authors developed a procedure for modifying the equations which model a load flow while retaining the same basic (Newton's Method) algorithm; this results in a program of increased power and efficiency.
Abstract: The standard approach to inclusion of a new feature or capability into a load flow program has been to modify whatever numerical algorithm was being used for solution. Usually, the efficiency of the algorithm suffered in the process. This paper develops a procedure for modifying the equations which model a load flow while retaining the same basic (Newton's Method) algorithm; this results in a program of increased power and efficiency.
TL;DR: In this article, the authors present the development of a single technique that simultaneously calculates several widely used power system reliability indices, such as frequency indices and partial capacity outages, and implement various techniques for handling the calculation of frequency indices.
Abstract: The overall objective of this sequence of papers [1]-[4] is to present the development of a single technique that simultaneously calculates several widely used indices of power system reliability. The sequence has already discussed generation and load models, indices of reliability used for generation planning, and models to represent multiple boiler-multiple turbine units and partial capacity outages. This part brings up for examination what the authors believe to be some of the more relevant generation planning problems. The paper presents methods for recognizing the effects of delays in unit installations and for implementing the various techniques for handling the calculation of frequency indices for two interconnected systems. Computer programs and numerical examples of the methods presented are also discussed.
TL;DR: In this paper, the frequency and duration indices can be computed for interconnected systems, and a general computer program for generating capacity reliability evaluation in single and interconnected systems is presented. But the application of these general concepts is limited to single-and interconnected systems.
Abstract: The development of an approach by which frequency and duration indices can be computed for interconnected systems was illustrated in Part I of this paper entitled "Mathematical Analysis". Equations were developed for a system connected to one or to more than one other system. These equations have been incorporated in a general computer program for generating capacity reliability evaluation in single and interconnected systems. This portion of the paper entitled "System Applications" illustrates the numerical application of these general concepts.
TL;DR: In this article, the problem of choosing the stabilizing structures of power system generators with forced excitation control reliably ensuring steady-state stability of the system operation is considered, and the synthesis method outlined for this purpose makes it possible to determine (with minimum stability calculations) both the generator operational condition parameters and the orders of their derivatives to be used for the control stabilization.
Abstract: This paper considers the problems of choosing the stabilizing structures of power system generators with forced excitation control reliably ensuring steady-state stability of the system operation. The synthesis method outlined for this purpose makes it possible to determine (with minimum stability calculations) both the generator operational condition parameters and the orders of their derivatives to be used for the control stabilization.
01 Dec 1971
TL;DR: Particular state variable representations for load frequency control of a linearized two-area interconnected power system were developed in this paper, where a comparison of the resulting modern optimal feedback controllers with the conventional are made.
Abstract: Particular state variable representations are developed for the load frequency control of a linearized two-area interconnected power system. Associated cost functionals are developed emphasizing differences between the various state variable configurations. Comparison of the resulting modern optimal feedback controllers with the conventional are made.
TL;DR: This paper shows how Kron's B coefficients can be calculated by Tinney's optimally ordered direct solution techniques which exploit the sparsity of the network admittance matrix.
Abstract: The on-line economic dispatch of electric power systems is usually accomplished by use of loss formulas employing B coefficients. This paper shows how Kron's B coefficients can be calculated by Tinney's optimally ordered direct solution techniques which exploit the sparsity of the network admittance matrix. The new technique is much faster, more accurate, and more reliable than currently used iterative techniques. In addition, it rigorously handles systems with phase shifters and static elements to ground with no difficulty. Precise timing of sample system experiments (5 to 160 nodes) documents the greatly improved solution efficiency.
TL;DR: A modified version of the complex method of Box is used for the minimization of bus voltage deviation in the first phase of optimization and a numerical search technique for the reduction of transmission losses due to reactive power flows in the second phase.
Abstract: An efficient computational algorithm is presented for the real-time control of system voltage and reactive power on the basis of a simplified linear model. A modified version of the complex method of Box is used for the minimization of bus voltage deviation in the first phase of optimization and a numerical search technique for the reduction of transmission losses due to reactive power flows in the second phase. The numerical example for a sample practical system is also given.
TL;DR: In this paper, an optimal excitation control for the stability of synchronous machines is found in a closed form using Pontryagin's minimum principle, and the results obtained for the single machine- infinite bus case indicate that such control provides major benefits in removing transients.
Abstract: An optimal excitation control for the stability of synchronous machines is found in a closed form using Pontryagin's minimum principle. While the optimal control is bang bang, in practice it is necessary to compromise with normal voltage regulator action to produce a sub-optimal control. The time required for stabilization is slightly increased by this. The results obtained for the single machine- infinite bus case indicate that such control provides major benefits in removing transients.
TL;DR: In this article, a field test program is described which was used to evaluate and then to adjust the 33 power system stabilizers installed on the Pacific Gas and Electric Company's system.
Abstract: A field test program is described which was used to evaluate and then to adjust the 33 power system stabilizers installed on the Pacific Gas and Electric Company's system. Also included is a comparison of the results of these tests with those of a digital computer simulation.
TL;DR: In this article, the Self-Adjusting Accelerator (SAA) is proposed for load-flow optimization in a power system network load flow problem, and a mathematically rigorous solution is obtained using less computer time than any other nodal iterative method.
Abstract: Introducing the Self-Adjusting Accelerator, a completely new digital computer method of solving a power system network load-flow is presented. With no sacrifice in accuracy, a mathematically rigorous solution (employing A B C D1 constants) is obtained using less computer time than any other nodal iterative method.
TL;DR: It is shown how hybrid computers formed from special- purpose analog modules and process-control- type digital computers can be used to solve power system load flows more rapidly than by digital computation alone.
Abstract: It is shown how hybrid computers formed from special- purpose analog modules and process-control- type digital computers can be used to solve power system load flows more rapidly than by digital computation alone. For a 181-bus system, a particular hybrid computer has been built that requires about 20 seconds for each solution as compared with 30 minutes for an all-digital solution with the same computer.
TL;DR: A solid-state acceleration relay has been developed by the Bureav of Reclamation for data acquisition, but with potential, also for use in generator dropping and load shedding schemes as mentioned in this paper.
Abstract: A solid-state acceleration relay has recently been developed by the Bureav of Reclamation for use in data acquisition, but with potential, also for use in generator dropping and load shedding schemes. A pilot model of the relay has been installed at Palisades Powerplant in Idaho to assist in collection of system performance parameters. Data acquired during a major system disturbance demonstrate the potential value of the acceleration relay for sensing behavior and for eventually improving power system reliability.
01 Dec 1971
TL;DR: In this article, the control of a two area interconnected power system subjected to disturbance inputs is discussed from the viewpoint of optimal stochastic control theory, and the control is shown to be optimal.
Abstract: The control of a two area interconnected power system subjected to disturbance inputs is discussed from the viewpoint of optimal stochastic control theory.
TL;DR: In this article, a method for finding the closed-loop time optimal excitation control for a power system by applying Pontryagin's minimum principle is presented, and numerical results are presented for single machine-infinite bus problems implementing such control.
Abstract: A method is presented for finding the closed-loop time optimal excitation control for a power system by applying Pontryagin's minimum principle. Numerical results are presented for single machine-infinite bus problems implementing such control.
01 Dec 1971
TL;DR: In this article, the load flow analysis of a power system is treated as a circuit analysis problem by converting all generators and loads into equivalent current sources, which gives rise to much convenience in tearing the system and analysing it by parts.
Abstract: In this paper the load flow analysis of a power system is treated as a circuit analysis problem by converting all generators and loads into equivalent current sources. This representation gives rise to much convenience in tearing the system and analysing it by parts. This procedure facilitates the solution of a large power system on a small size computer. The nodal admittance method adopted here for network solution is shown to have better convergence. Other simulation techniques tried for the loads and generator representation using the mesh method of analysis are also given.