Showing papers on "Power-flow study published in 1977"

A second order load flow technique

Abstract: This paper presents a second order load flow technique based on the Taylor series expansion of a multivariable function. An algorithm for obtaining digital solutions by the proposed approach is described. Six simplified versions of this algorithm are also discussed. The proposed algorithm and its modifications have been tested by obtaining load flow solutions of a five bus system, the 26 bus Saskatchewan Power Corporation transmission network model and the IEEE 14 bus, 30 bus, 57 bus and 118 bus test systems. The effectiveness of these algorithms is compared with the performance of the Newton Raphson approach and some of the results from these studies are presented.

A new state space for emergency control in the interconnected power system

Abstract: A new state space is introduced for the large interconnected power system in which the state of the system can be estimated piecewise by local computations from conventional local measurements. The new state space is defined, its mathematical equivalence to the conventional state space is proven, and initial illustration is provided of its usefulness.

Isolated electrical power generation system with multiple isochronous, load-sharing engine-generator units

Abstract: An isolated electrical power generation system is described with multiple isochronous, load-sharing engine-generator units. The system includes load sensing means for generating a signal representing the individual power output of each engine-generator unit, means for generating a signal representing the total power output of all the engine-generator units in the system, and load-sharing means responsive to deviations between each individual power output signal and the total power output signal for controlling the fuel inputs to the respective engines in the various units. A load simulating means responds to the occurrence of a preselected condition, such as an excessive temperature, in an individual unit for adding a simulated power output signal to the individual power output signal for that particular unit. This reduces the fuel input unit to that particular unit without reducing the total power output signal, thereby avoiding a reduction in the fuel inputs to the other units and a resultant reduction in the frequency of the power output of the system.

Operating cost calculation of an electric power generating system under incremental loading procedure

Abstract: A phased approach to calculating the expected operating cost of a power system, under the incremental loading procedure, is presented. The units in the system are divided into subsets according to their marginal cost characteristics. The contribution of each subset to the operating costs of the system is then derived in a recursive manner, taking maintenance and forced outages into account. The procedure is also extended to yield the expected amount of energy delivered by each unit in the system as well as the expected fuel cost for each unit. Given the unit cost of fuel, the expected amount of fuel consumed by each unit is easily derived.

Security constrained economic dispatch with participation factors based on worst case bus load variations

Abstract: An efficient method is presented for finding the economic and steady-state secure base point generation levels to supply the present load. From the specified range of possible load variation anticipated for each bus during the interval before the next base point optimization, the generator participation factors are calculated to guarantee a secure supply to the worst case combination of bus load excursions. The base points are calculated using a linear but lossy system model coupled with an efficient gradient computation technique. The worst case bus load condition is found as an extension of the base point calculation.

Reactive Power Meter for Nonsinusoidal Systems

Abstract: This paper describes a novel reactive power meter realized by electronic circuits that determine successively the terms of the equation Q = ?n=1?VrIrsin?r for n significant harmonics. The harmonic contributions to the total reactive power is determined by electronic simulation of the mathematical expression that sets the orthogonal condition of two functions in a periodical interval. Partial reactive power with its sign are stored and added in a circuit to get at the end of the cycle the total reactive power. A control system permits operation in a repetitive form.

A modified method for solving the economic dispatching problem

Abstract: A method is developed for solving the economic dispatching problem by changing it from constrained nonlinear programming problem to a sequence of constrained linear programming problems. The formulation of the load scheduling is exact in the sense that all the system voltages, active and reactive generation, as well as the phase angles are considered as independent variables. In addition, the effect of bus voltages on the loads is taken into consideration. Also any type of load can be included in the system constraints without altering the solution. The feasibility of the technique is demonstrated by means of a sample system.

Estimation of transient state of multi-machine power system by extended linear observer

Abstract: The development of extended linear observer estimating the transient state of power system has been made previously [5], using one-machine infinite bus system. In this paper, the application of this estimation technique to the multi-machine system is investigated. To get the good estimation performance defining the fast convergency of estimated value to the true value, the choice of specific combination having the least number of measurments from among a large number of combinations is most desirable. The examination is made at first, in one-machine infinite bus system, next, in multi-machine system. The results of computer simulation conclude that, at least, one measurement from each electrical and mechanical system should be adopted.

Dynamic stability and power system stabilizersߞAnalysis and tests on the Venezuelan system

Abstract: The nature of undamped oscillations in a power system is closely examined in this paper and an experimental approach is proposed for the adjustment of the power system stabilizers to damp these oscillations. A description is given of the poorly damped and occasionally sustained oscillations that the Venezuelan Interconnected power system experienced after the installation of high initial response solid-state exciters and a detailed discussion is presented of the results of tests performed on the power system with stabilizers adjusted using the experimental approach proposed.

A Penetrating Gaze at One Open Phase: Analyzing the Polyphase Induction Motor Dilemma

Abstract: Portions of the material proposed for a chapter in a new IEEE Standard (#399-the ``Brown Book'') being prepared by the Power System Analysis Subcommittee of the I & CPS Committee are presented. In order to establish a library of approved analytical methods, the material provides a review of the more important basic electrical circuit analysis techniques used for determining the voltage and current relationships which describe various power system network events and operating conditions. Certain simplified circuit arrangements are examined. They illustrate the power and merit of the analytical methods that evolve, as well as the errors that can occur because of improper regard for the restraints that apply. Using the analytical methods, the classical problem of a three-phase induction motor operating with one phase of the supply line open-circuited is studied in considerable detail. Finally, important observations and conclusions are presented regarding the motor protection requirements.

Power System State Measurements for Transient Control Augmentation Using Digital Techniques

Abstract: Any strategy, considered reasonable for the control of transient modes which occur as the result of a major disturbance in a large electric power system, will require fast and reasonably accurate measurements of at least two states per machine, namely, rotor speed deviation and torque angle. Since any control strategy will probably require an on-line digital computer for decision, computation, and execution, minimal computation time for the determination of state is imperative. Such a computer based technique along with the pertinent hardware for implementation is presented in this paper.

Optimal power system operation-analysis techniques

Abstract: A study of power system operation optimization is presented for the purpose of establishing trends in the evolution of power system operation and to begin development of the tools and techniques required for this evolution. A general technique of using linear optimization and linearization of nonlinear quantities is followed. This study concluded that: the developed techniques are applicable to real-time and on-line computer control and operation of power systems; very well developed software package can be used; generation and power flow optimization are carried out within safe margins, and will not disturb system security; this analysis is applicable to reactive power as well as real power and could be implemented in dc, ac, or a combination dc and ac transmission system; and the developed techniques could be useful for system planning and scheduling, as well as operation. (LCL)

Electric Power System Hardening to Nuclear EMP

Abstract: Most nuclear explosions produce an Electromagnetic Pulse (EMP). Surface explosions produce blast effects which are far more destructive than the EMP effects. How­ ever, with exoatmospheric bursts, since there is no significant overpressure, the EMP becomes a dominant threat. Furthermore, EMP travels in line-of-sight fashion to the horizon; the higher the altitude of detonation the great­ er the area affected. Thus, a large portion of the Un itedStates could be affected by EMP from a single exo­ atmospheric blast. The transmission lines and other elements of an entire electric power system grid could be suddenly and almost simultaneously illuminated by very intense electromagnetic fields. Because of this dominant role for high altitude nuclear events, this paper considers the EMP effects resulting solely f r omsu ch bursts.

Effects of large interconnected wind generators on the electric power system

Abstract: 3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row and continuing on until complete.

Sparsity and decoupling in load power flow analysis

Abstract: This paper presents some recent ideas on and methods created by power engineers for the solution of the Load Flow Problem. Beginning with an analysis of the solution of large systems of linear equations, techniques employing elementary matrix operations are discussed to reduce the amount of calculations necessary to achieve repeated solutions. Recent interest in taking advantage of the characteristic sparsity of the admittance matrix is also examined. The problems of operating on and computer storage of large sparse matrices are investigated. Methods to efficiently order, store and work with large sparse matrices are discussed and demonstrated. The general acceptance and use of Newton's Method by power engineers for Load Flow Studies has resulted in many variations on it. Together with a review of the Load Flow Problem and Newton's Method, an analysis of three related methods is presented and a comparison of their characteristics is made to Newton's Method. This paper serves to keep the power engineer abreast of the many recent advances available for conducting Load Flow Studies. APPROVAL OF THESIS SPARSITY AND DECOUPLING IN LOAD POWER FLOW ANALYSIS BY KENNETH NAZIMEK FOR DEPARTMENT OF ELECTRICAL ENGINEERING NEW JERSEY INSTITUTE OF TECHNOLOGY