Showing papers on "Power-flow study published in 1970"

Power System Static-State Estimation, Part III: Implementation

Abstract: The static state of an electric power system is defined as the vector of the voltage magnitudes and angles at all network buses. The static-state estimator is a data processing algorithm for converting redundant meter readings and other available information into an estimate of the static-state vector. Discussions center on implementation problems associated with computation time requirements, dimensionality resulting from a large number of buses, and the actual time-varying (nonstatic) character of power systems. Various potentially useful approaches are discussed and compared.

A Mathematical Optimization Technique for the Expansion of Electric Power Transmission Systems

Abstract: Planning the expansion of a high-voltage transmission system involves deciding which new lines will enable the system to satisfy forthcoming loads with the required degree of reliability. Since these decisions involve considerable investment and operating costs, the planner will wish to keep the present worth of all costs as low as possible. The difficulties of the problem come from the tremendous number of possible alternatives, the need to make the best use of information about future loads, and the complexity of the reliability constraints: The outages of some specific combinations of lines (highest capacity lines among them, perhaps) must not at any time overload any other line in the system. A new computational procedure for system planning is presented; this procedure combines and optimizes the formerly separate computations of load flow, reliability analysis, and economic evaluation. This procedure has been applied successfully to a 17-node system studied by the Bonneville Power Administration.

State Calculation of Power Systems From Line Flow Measurements

Abstract: This paper describes a new and efficient method for computing a real-time load flow solution of a power system network. The use of line flow measurements is proposed and it is shown that this measurement scheme shows superiority in speed, accuracy and numerical behavior together with advantages in error detection and identification.

Power System Dynamic Equivalents

Abstract: This paper describes a method for determining a simplified equivalent mathematical representation of portions of a power system for transient stability analysis The method leads to equations that do not correspond directly to a system composed of normal power system components Conditions under which it is possible to obtain such an equivalent are given, and the results of applying the method to the 118-bus IEEE test system are reported

State Estimation in Power Systems Part II: Implementation and Applications

Abstract: State estimation is a digital processing scheme which provides a real-time data base for many of the central control and dispatch functions in a power system. Its purpose is to permit improvements in system security and data accuracy and to reduce measurement and telemetry cost. The on-line implementation of an efficient state-estimator algorithm is discussed, and its feasibility is demonstrated on a 400-node network. The main motivations for and potential applications of on-line state estimation are listed, and the tradeoffs between measurement, estimation, and on-line load- flow computation are briefly discussed.

Improvement of Power System Transient Stability Using Optimal Control: Bang-Bang Control of Reactance

Abstract: The problem of restoring a power system to its initial steady state in minimum time after a transient disturbance is identified as a minimum time problem in optimal control theory. The optimal control obtained to achieve this objective, by use of Pontryagin's maximum principle, is bang-bang control of line reactance. The implementation of this scheme on a simple power system model is shown, along with numerical results.

Power System Operation

Abstract: Basic Principles. Transfer of Energy in Power Systems. VAR Flows. Economic Operation of Power Systems. Power System Control. Energy Accounting in Interconnected Disciplines. Power System Communication. Telemetering Methods. Supervisory Control and Data Acquisition System. Power System Reliability Factors. Power System Protection. Power System Stability. EHV Operation.

Techniques for the Real-Time Monitoring of Power System Operations

Abstract: This paper describes methods for using power system readings to compute a real-time power flow solution of the transmission network. The use of redundant data is discussed and procedures are outlined to detect, identify, and correct for data errors. Several examples are presented and the numerical behavior of the methods is discussed.

Transmission Planning Using a Reliability Criterion, Part I: A Reliability Criterion

Abstract: The utilization of a quantitative reliability criterion in long range transmission planning is proposed. The application of a conditional probability approach the determination of load point reliability indices in practical systems is discussed and illustrated by a simple hypothetical system study. Failure at a bus is defined by three planning criteria and the reliability level obtained in terms of a probability and an expected frequency of bus failure. The method requires ac load flow analysis at several load levels under possible system component outages. The technique is quite general, and any known operating conditions can be included. Planning based on acceptable load bus reliability levels results in optimum utilization of the investment placed in transmission facilities.

A Method of Improving Power System Transient Stability Using Controllable Parameters

Abstract: Controllable parameters in a power system include generator terminal voltage, generator input power, and network admittances. These parameters can be controlled to damp mechanical rotor oscillation in the generators and thereby improve system transient stability. Explicit equations are derived for the control of these parameters to introduce damping uniformly throughout a large power system. These equations are derived on the basis of minimizing a positive definite error function. Decision functions are included which inhibit damping action when it leads to system instability. This method can be used to coordinate the application of locally based damping techniques.

New Integration Algorithms for Transient Stability Studies

Abstract: New integration algorithms suitable for power system transient stability studies are developed and applied to a simple power system example. Both theoretical and preliminary experimental investigations indicate that the new algorithms operate satisfactorily at step sizes five or even te l times those necessary to assure numerical stability when using conventional one-step and multistep methocls. Since the computation time per integration time step of the new methods is similar to that of the conventional methods, the new methods offer significant saving in overall computing effort.

Block Diagram Approach to Power System Reliability

Abstract: The Markov process concept is used to derive expressions for an equivalent of two units in series and parallel considering two-state conditions of fluctuating normal and stormy weather. These expressions are then used to simplify a system by the series and parallel block reduction technique. It is observed that this technique alone is not sufficient for a system where a complex configuration is involved. For such cases, star-delta conversion in addition to the series and parallel equivalents is used. The results obtained by this technique are compared with those obtained by existing methods. Finally a computer algorithm for system reduction is described.

Step-by-Step Formation of Bus Admittance Matrix

Abstract: An algorithm has been developed to form the bus admittance matrix Ybu,, by forming the network through a step-by- step addition of a line or a passive element to the system, taking into account the mutual coupling between the elements. Two sets of formulas have been derived for the addition of a tree branch and for the addition of a link. This method eliminates the formation of incidence matrices and does not require singular or nonsingular transformations. This algorithm is very convenient for calculation in digital computers.

New Stability Measure for Multimachine Power Systems

Abstract: A new measure of the relative transient stability of a multimachine power system based on the Lyapunov stability theory is introduced. Techniques of sensitivity analysis are used to determine numerically the influence of variations or errors in the estimation of the system parameters on the transient stability of a power system. In particular, data is presented for an application of these ideas to a one machine infinite bus system.

Digital Representation of a DC Transmission System and Its Controls

Abstract: This paper discusses the mathematical representation of a dc transmission system and its controls. Presented for comparison are digital computer study results of the same studies performed on an intermediate power level model of a parallel ac/dc transmission system. Also presented are the mathematical representations of the several ac components of the model system.

H.V.D.C. Stations Connected to Weak A.C. Systems

Abstract: The operation of a h.v.d.c. converter station connected to a three- phase power system having a low short-circuit capacity gives rise to a series of special problems which must be treated together in order to produce an economic solution for the whole transmission system. The design of the reactive power supply for such a system is given particular attention and the question of a suitable grid control method for the converters is discussed in connection with the problem as a whole. In this way the complete technical and economic framework for the economic layout of a h.v.d.c. station fed by a weak a.c. system is demonstrated.

New approach to power-system load-flow analysis in a digital computer

Abstract: The paper describes a method of evaluating power-system load flow on a digital computer, which is based on established network-analyser techniques. The technique does not rely on sophisticated mathematics for convergence. It has been used satisfactorily on a wide range of power systems, for which previously reported digital load-flow techniques completely failed.

An Indefinite Admittance Network Description for Fault Computation

Abstract: An algorithm for constructing the admittance matrix of a power system is given which is based upon the concept of an indefinite admittance matrix. The application of this algorithm to a power system with mutually coupled elements is discussed. The simplicity of the method is illustrated by means of an example.

Prevention of Power Failures in Major Networks

Abstract: An outline of the philosophy underlying the Federal Power Commission's study of the reliability of electric power systems and their distribution networks is presented. A broad review of bulk power system reliability is given. The steps required for the prevention of major power outages of wide extent and substantial duration are set forth.

Power system load flow analysis by digital computers

Abstract: This paper outlines the Glimn-Stagg and the Newton-Raphsun methods of solving the power system load flow problem. Results of a 5-bus network obtained by the IBM 1130 computer are given. Flow charts and computer programs using the Fortran IV language are presented.

Determination of Reference Operating Voltages in Power Systems

Abstract: In advance of the integrated voltage and reactive power control in a power system, it is necessary to determine an appropriate reference operating voltage, that is, the desired operating values at generating plants and substations The reference operating voltage used so far, determined mainly from experience, cannot be said to be reasonable A newly developed method to determine the appropriate reference operating voltage and also a machine computation program is described in detail In addition, the results of applying these methods and programs to a model power system are also mentioned