Showing papers on "Power system simulation published in 1973"

Effects of Synchronous Machine Modeling in Large Scale System Studies

Abstract: A study was made of the accuracy of utility power system stability simulations, as affected by the complexity of the synchronous generator models and the data used with the models. The investigation was performed by simulating the operation of a representative multimachine power system with many combinations of disturbance, initial load, system stiffness, model detail and model data. The findings from this study provide guidelines for the selection of the simplest computational machine models for use in large scale stability analyses, with the goal of minimizing the cost of computer usage while assuring sufficient accuracy of the results. Recommendations are made for selecting machine data more suitable for use in stability studies than the standard machine data.

System Load Dynamics-Simulation Effects and Determination of Load Constants

Abstract: Justification for using more realistic load models in stability studies than has been the practice heretofore is presented below. Examples are given which show that stability tests may be dramatically affected by load-voltage characteristics, or that more sophisticated models are necessary under conditions which preclude the usual composite load assumptions. In conclusion the paper states that system measurements are the most practical means of obtaining realistic load-voltage data for use in computer stability programs.

Application of Pattern Recognition to Steady-State Security Evaluation in a Power System

Abstract: Power system operation is outlined and system security is defined. The need for security evaluation in power system operation is discussed, and the evaluation is presented as a pattern recognition problem. A suitable straightforward and quick procedure is used to select a small number of variables as features from a large set of variables which are normally available in power systems. Comparison is made on the security classification performances of a number of different types ot classifiers. The training of classifiers is carried out by a search algorithm which seeks to minimize the number of classification errors. The procedure to determine the security functions (classifiers) is illustrated by an example, and simulation results on the steady-state security of the CIGRE 225-kV system show that the pattern recognition approach to security evaluation is encouraging. Some uses of security functions in the control and operation of power systems are outlined. The effect of many of these uses cannot be achieved as easily by other existing methods. Finally, some of the problems associated with the application of pattern recognition to power system security evaluation are discussed.

Electric power unit commitment scheduling using a dynamically evolving mixed integer program

Abstract: Prepared in association with Electric Power Systems Engineering Laboratory and Dept. of Civil Engineering, M.I.T.

Closed Loop Optimization of Power Systems with Two-Axis Excitation Control

Abstract: This paper describes the results of studies made to improve the dynamic response and damping torques of power systems incorporating synchronous machines with 2-axis excitation control. Dynamic optimization techniques have been used to determine the optimum controls subject to a quadratic integral performance index. The system has been simulated as a seventh order, closed loop, non-linear model incorporating speed governor and voltage and angle regulators. Modified quasilinearization and first order gradient methods have been utilized for solving the optimization problems for this non-linear system. The investigations indicate that optimal control of doubly excited synchronous machines is possible and that it yield, s improved transient performance. Incidentally, some possible limitations of the quasilinearization technique have also been brought out.

State Estimation of a Simulated Turbine Generator

Abstract: A model of a single steam turbine generator is developed which includes the effects of random load fluctuations observed in interconnected power systems. This model is used in the design of an on-line state estimator for an individual generator. A digital simulation of the generator model and state estimator indicates the state estimation procedure is feasible and can be implemented on a small control computer.

Simulation Techniques for Rural Electric Power Systems Planning

Abstract: This paper introduces an effective method for rural electrical systems planning. All three-phase, two-phase, and single-phase lines are simulated in one computer study. Typical load flow results are obtained from the study. The method emphasizes simplicity and flexibility. Very little computation time is required. Once the data are prepared the amount of work required to incorporate the changing of the system is small and very inexpensive. This type of flexibility is one of the most important contributions of this new method. The method applies to both long-range and short-term system planning.

On-Line Transient Control of Capacitor Switching to Improve System Stability

Abstract: Switching of series capacitors to improve system stability is of current interest. Investigations indicate that modern control theory might be applied to determine switching of a combination of series capacitors so that the system may be transferred from one state to another in minimum time and in a nonoscillatory manner. In these studies, a simplified voltage-reactance equivalent of the one-machine infinite bus system was used. The material presented in this paper shows that this simplified model does not predict the performance of a one-machine infinite bus system with the accuracy necessary to determine the capacitor switching times so as to achieve the control objectives. However, it is shown that computation accuracy may be improved by including system losses. It appears that in order to apply optimal control techniques it will be necessary to develop more accurate models of the power system components. Also, faster than real time iterative, on-line, computation techniques as simulatedc in this paper should be implemented and used to calculate the switching times. Until these obstacles are overcome, optimal control theory will have little impact upon the power industry.