scispace - formally typeset
Search or ask a question

Showing papers on "Power-flow study published in 1978"


Journal ArticleDOI
TL;DR: In this paper, a comprehensive method for planning reactive compensation in power systems so as to maintain voltages in acceptable ranges during contingencies is presented, which allows the addition of further VAR compensation as may be economically justified.
Abstract: This paper presents a comprehensive method for planning reactive compensation in power systems so as to maintain voltages in acceptable ranges during contingencies. The methodology allows the addition of further VAR compensation as may be economically justified. Reactive compensation considered consists of conventional shunt reactive compensation, synchronous condensers, as well as variable shunt reactive control devices called static VAR control devices. This work combines VAR optimization with static as well as with dynamic system performance evaluations. Necessary modelling of static VAR control devices for inclusion in dynamic performance programs is also given.

72 citations


Journal ArticleDOI
TL;DR: In this article, a steady state equivalent of a power system for use in real-time operation is described, which is the result of applying Dimo's REI method for the reduction of the electrical network and also for the provision of a means for on-line calibration.
Abstract: This paper describes a new steady-state equivalent of a power system for use in real-time operation. The equivalent is the result of applying Dimo's REI method for the reduction of the electrical network and also for the provision of a means for on-line calibration. Although this new equivalent is intended for application in system operation, it would also be useful in planning studies.

71 citations


Journal ArticleDOI
TL;DR: In this paper, a new approach is proposed for transient stability analysis of interconnected power systems, which is based upon the concept of vector Lyapunov functions and the decomposition-aggregation method.
Abstract: A new approach is proposed for transient stability analysis of interconnected power systems, which is based upon the concept of vector Lyapunov functions and the decomposition-aggregation method. The approach results in an exact procedure for computation of stability region estimates which are expressed explicitly in terms of system parameters. More refined models of the subsystems can be readily accommodated by the new approach. In particular, the transfer conductances are included in the present study, a feature which is almost exclusively missing in transient stability analysis of multimachine systems by Lyapunov's method.

51 citations


Journal ArticleDOI
J. Fong1, C. Pottle1
TL;DR: This paper investigates the suitability of utilizing simple, extensible parallel microcomputer structures for efficient simulation of power system transients by exploiting the sparsity structure of the equations involved.
Abstract: With the ever-increasing complexity of power systems, transient analyses are demanding a tremendous amount of computer effort. Recent advances in microprocessor technology have developed inexpensive processing units and memory as a set of small chips. This paper investigates the suitability of utilizing simple, extensible parallel microcomputer structures for efficient simulation of power system transients. Algorithms exploiting the sparsity structure of the equations involved are discussed and simulated results are presented.

46 citations


Journal ArticleDOI
Shigeo Abe1, N. Hamada1, Akira Isono1, K. Okuda1
TL;DR: In this article, a region where a set of initial values converges to a stable load flow solution under specified conditions, is investigated theoretically when the Newton-Raphson method is applied to a subset of nodal power equations expressed in either polar or rectangular coordinates.
Abstract: Because load flow problems are expressed as sets of nonlinear simultaneous equations, they have no unique solutions. In this paper a region where a set of initial values converges to a stable load flow solution under specified conditions, is investigated theoretically when the Newton-Raphson method is applied to a set of nodal power equations expressed in either polar or rectangular coordinates. The results are tested in load flow calculations on a 28-node power system and the convergence characteristics for the two types of coordinates are compared.

42 citations


Journal ArticleDOI
TL;DR: In this paper, a power system composed of a turbo-generator set connected to an infinite bus via series capacitor-compensated transmission lines is analyzed for subsynchronous resonance.
Abstract: Studies of subsynchronous resonance (SSR) phenomena are conducted in a power system composed of a turbo-generator set connected to an infinite bus via series capacitor-compensated transmission lines. The analysis is applied to a "bench mark" model proposed by the special IEEE Power Engineering Society Task Force on Subsynchronous Resonance.

37 citations


Journal ArticleDOI
TL;DR: In this article, a method of finding the optimum shift in generation to eliminate overloading of lines and transformers or to maintain fixed flows on tie lines is presented, which incorporates the concept of generalized inverse matrices, and the sensitivity matrix of power systems.
Abstract: This paper presents a method of finding the optimum shift in generation to eliminate overloading of lines and transformers or to maintain fixed flows on tie lines. It incorporates the concept of generalized inverse matrices, and the sensitivity matrix of power systems.

30 citations


Journal ArticleDOI
TL;DR: The influence of generator capability chart representation (overexcited zone) on system voltage and reactive power control studies is examined and possible criteria for the optimization of system voltage, reactive power scheduling in critical conditions are discussed.
Abstract: The influence of generator capability chart representation (overexcited zone) on system voltage and reactive power control studies is examined. A load pick-up in a power system is simulated by means of a computer program and the steady--state operation in some "critical" conditions (heavy power flows and low power factors) is analyzed. Under these conditions the adoption of the simplified representation (rectangular) or of a more exact representation of the actual capability charts, may influence the search for feasible solutions to a considerable extent. Possible criteria for the optimization of system voltage and reactive power scheduling in critical conditions are also discussed on the basis of this more L exact representation.

20 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a planning model suitable for minimizing system energy costs over a specific time period in the long range time frame, which includes fossil fired, nuclear and hydro units.
Abstract: The integrated power system which includes fossil fired, nuclear and hydro units has need for a planning model suitable for minimizing system energy costs over a specific time period in the long range time frame. This paper presents such a model. Predicted partial and total forced outages, scheduled down time for various unit maintenance activities, cost of operation for various valve loadings and stochastic river flow data are inputs to a program which yields hydro energy scheduling for most economic loading over the time frame.

15 citations


Journal ArticleDOI
TL;DR: In this paper, the authors apply the concepts of hierarchical system theory in conjunction with power system engineering to enable the real-time control of a large-scale power distribution system, where the overall control strategy for each substation is decomposed into independent control functions which are ordered (ranked) to meet a hierarchy of control requirements specified by the system's physical operation.
Abstract: The concepts of hierarchical system theory, in conjunction with power system engineering, have been applied to enable the real-time control of a large-scale power distribution system.1 The control objective of the distribution system consists of security (equipments protection) and operation (continuity of service) requirements to be satisfied within the feasible control boundaries for all substations composing the distribution system. The overall control strategy for each substation is decomposed into independent control functions which are ordered (ranked) to meet a hierarchy of control requirements specified by the system's physical operation. This approach was adopted not only to simplify the real-time control problem solution, but also was necessitated by the requirement that a partial feasible solution be provided which meets higher priority objectives when a total feasible solution does not exist. This paper describes, in the hierarchical framework, the physical process, the network decomposition and modeling, the control decomposition and criteria, and the control procedure along with numerical results.

15 citations


Journal ArticleDOI
TL;DR: This paper is a contribution to the improvement of transient stability of parallel ac-dc power systems by use of the optimal switching control.
Abstract: This paper is a contribution to the improvement of transient stability of parallel ac-dc power systems by use of the optimal switching control.


Journal ArticleDOI
TL;DR: In this article, a graph-theoretic approach was used to develop a linearized state model for a typical hydro-power system effectively and systematically, which is applicable to multi-machine systems and is easily amenable to digital simulation.
Abstract: The paper demonstrates a powerful application of graph-theoretic approach in developing a linearized state-model for a typical hydro- power system effectively and systematically. The linearized d-q state models of basic components of power system such as generator, transformer, transmission line are formulated (conceptually, in isolation) in a synchronousiy rotating frame which permits ease of inter- connection without involving any intermediary of axis transformations. The formulation of model in general, is applicable to multi- machine system and is easily amenable to digital simulation. It is hoped that the system state-model formulation through graph-the- oretic approach would strongly appeal to power system engineers engaged in large-scale comprehensive dynamical system studies.

Journal ArticleDOI
01 Aug 1978
TL;DR: Two methods of computing the instantaneous reactive power from concurrent samples of voltages and currents are suggested and such a fast computation finds applications in protection, load behavior modelling, state estimation, reactive power compensation, etc.
Abstract: Two methods of computing the instantaneous reactive power from concurrent samples of voltages and currents are suggested. The advantages are not having to wait for a quarter of a cycle, consistency with the active power computation, and a simple measurement of the deformation factor. Such a fast computation finds applications in protection, load behavior modelling, state estimation, reactive power compensation, etc.

Journal ArticleDOI
TL;DR: This analysis is based on studies that have been carried out in Ref. 1 to determine the maximum simultaneous power interchange capability into an area from its neighboring areas based on off-line computer analyses.
Abstract: This analysis is based on studies that have been carried out in Ref. [ 1 in which the procedure is developed to determine the maximum simultaneous power interchange capability into an area from its neighboring areas. Such procedure is based on off-line computer analyses.

Journal ArticleDOI
TL;DR: In this paper, a new approach to transient stability analysis of a large-scale electric power system based on the two-level structure of a power system has been suggested, where at the lower level, comprising controlled synchronous machines, the state vector is estimated using the new static state estimation method presented here.

Journal ArticleDOI
TL;DR: In this article, the case where multistabilizing apparatus exists in a power system is considered, and the following problems are discussed: mutual interaction between these multi-stabilizing apparatuses, totalized control of the multisensor apparatus, optimal allocation of multislabeling apparatus, and confirmation of the effectiveness of these apparatus by simulation method.
Abstract: Many devices are used to improve the stability of power systems. The power system stabilizer (PSS), dynamic braking resistor (DBR), and switching capacitor (SWC) are some examples. These devices can be used to secure the stability of a wide area power system. The case where multistabilizing apparatus exists in a power system is considered, and the following problems are discussed: mutual interaction between these multistabilizing apparatuses; totalized control of the multistabilizing apparatus; optimal allocation of multistabilizing apparatus; and confirmation of the effectiveness of these apparatuses by simulation method.

Journal ArticleDOI
TL;DR: In this article, the authors propose a reliable, cost effective method of connecting 480 volt ac non-Class 1E loads to the Class 1E ac power systems, which is a non-class 1E power system.
Abstract: Nuclear plant designers frequently seek a reliable, cost effective method of connecting 480 volt ac non-Class 1E loads to the Class 1E ac power systems.

Journal ArticleDOI
TL;DR: A discussion of various approaches to modelling the bulk load as seen at a high voltage bus of an electric power system leads to a mathematical model and an analogue representation suitable for an Electronic Power System Simulator.

Journal ArticleDOI
TL;DR: In this article, the stability of a weakly interconnected system can be tested using the zero-separating eigenvalue, and the stability test of a strongly interconnected system and the global behavior of a zero separating eigen value must be studied in detail in detail.
Abstract: How the loading condition and the interconnection strength affect the stability of an interconnected system are studied. Mathematically speaking, the stability of a weakly interconnected system can be tested using the zero-separating eigenvalue. For a complicated multimachine interconnected system, it is possible to test the stability using stability test index. Although a longitudinal-type interconnected system has been dealt with, the proposed method is applicable to interconnected systems in general. The stability test of a strongly interconnected system and the global behavior of a zero-separating eigenvalue must be studied in detail in the future.

Journal ArticleDOI
TL;DR: In this article, a step-by-step network reduction technique is described to provide realistic simulations of power systems with nonlinear loads, and the authors show that the errors introduced by the network reduction are quite tolerable provided angular swings and voltage deviations at retained buses are not excessive.
Abstract: This paper describes a step-by-step network reduction technique which is accurate enough to provide realistic simulations of power systems with nonlinear loads. This method has been developed at Arizona State University as a part of an ongoing research program sponsored by the Electric Power Research Institute to investigate methods of economically extending transient stability simulations. Test results; from up to 49 bus examples indicate that the errors introduced by the network reduction are quite tolerable provided the angular swings and voltage deviations at retained buses are not excessive.