Showing papers on "Power system simulation published in 1977"

An Application of Lagrangian Relaxation to Scheduling in Power-Generation Systems

Abstract: Two major decisions are made when scheduling the operations of a fossil-fuel power-generating system over a short time horizon. The “unit commitment” decision indicates what generating units are to be in use at each point in time. The “economic dispatch” decision is the allocation of system demand among the generating units in operation at any point in time. Both these decisions must be considered to achieve a least-cost schedule over the short time horizon. In this paper we present a mixed integer programming model for the short time horizon power-scheduling problem. The objective of the model is to minimize the sum of the unit commitment and economic dispatch costs subject to demand, reserve, and generator capacity and generator schedule constraints. A branch-and-bound algorithm is proposed using a Lagrangian method to decompose the problem into single generator problems. A sub gradient method is used to select the Lagrange multipliers that maximize the lower bound produced by the relaxation. We present...

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.

Hybrid simulation for long term dynamics

Abstract: This paper describes the work done under the EPRI RP908-1 project to study the long-term dynamics of power systems using hybrid simulation. A hybrid simulator was designed, constructed and tested at the University of Missouri-Columbia for a sample system provided by General Electric in RP907-1. The sample system consists of 16 machines and 68 buses. Each power system component was implemented in electronic integrated circuits and is contained on 8" × 10 1/2" printed circuit cards. The power system model is an ac, single phase, variable frequency, simulation scaled to operate 20 times faster-than-real-time. The base frequency is 1200 Hz which means that a 20 minute real time run can be obtained in one minute system running time. A 16-bit digital minicomputer was used for input, output and control of the analog simulation. A special purpose digital/analog interface controller was designed and built to achieve the desired data collection and control functions. The analog power system models include all of the specific components which influence the long term dynamics. A description of the hybrid simulator, and the results of the specific studies performed are presented. Two scenarios demonstrating the long term analysis capability of the simulator are presented along with a comparison of short-term results with a conventional digital program. This project has successfully demonstrated the basic feasibility of the hybrid approach to perform long-term dynamics studies and has demonstrated a working model of a faster-than-real-time hybrid simulator. Furthermore, it was shown that the hybrid approach is feasible and practical for a wide range of additional studies and purposes.

Applications of dynamic programming to energy planning and scheduling problems

Abstract: Dynamic programming has long been recognized as a very powerful approach to optimization problems. However, its applicability has been somewhat limited because of the high computational requirements of the standard computational procedure. Fortunately, in recent years a number of new computational techniques have been developed for reducing the computational burden while retaining most of the desirable properties of the basic method. Many of these advanced techniques have been developed for solving problems in the area of energy system planning and scheduling. The purpose of the paper is to review a number of specific problems where dynamic programming has been successfully applied. These problems include national energy planning, utility expansion planning, generation scheduling, unit commitment, and automatic generation control. In all cases the problem formulation is given, effective dynamic programming solution algorithms are presented and experience in applying the algorithms to specific problems is cited.

Electric power networks

Abstract: An overview of network problems in power systems is provided. Discussion is devoted to problems in the following areas: (a) steady-state analysis, (b) transient and dynamic stability analysis, (c) electrical transients, and (d) electromagnetic transients. Analysis problems in each area range from those of pure simulation and adequate modeling to those of optimal control, non-linear optimization, stochastic analysis, identification techniques, and hierarchical control. Some of the key developments are discussed with reference for possible future problems.