Showing papers on "Power system simulation published in 1982"

Variable Structure Control of Electric Power Generation

Abstract: A control scheme to reduce the mismatch in power generation and consumption of electric power systems is developed using the variable structure systems concept. This scheme is introduced to refine the dynamic properties of the presently used integral controller which has been originated in accordance with a steady state concept. The new controller changes its structure according to a certain logic which results in distinct advantageous properties.

Long-Range Generation Planning Using Decomposition and Probabilistic Simulation

Abstract: This paper discusses application of mathematical programming decomposition techniques in a model for planning least-cost investments in generating capacity subject to reliability constraints. The planning problem is decomposed into a set of subproblems, each representing theoperation of a set of generating units of fixed capacity in one year, and a master problem, representing optimal generating capacity investments over the entire planning horizon. The subproblems are solved using the probabilistic simulation procedure. The master problem is a linear program which uses Lagrange multipliers derived from the sub- problems. The solution is found by iteratively solving the master problem and the subproblems.

A New Aggregation Method for Determining Composite Load Characteristics

Abstract: A new aggregation method for deteining load characteristics for representation in computer simulations is proposed. In support of the new method, a mathematical derivation is presented. Also, results are compared with models obtained by using the EPRI/University of Texas at Arlington method and field tests. The application of the proposed method is simpler than existing methods in that it does not require field tests or the use of curve fitting techniques. The procedure should be of primary interest to transmission system planners involved in load flow and dynamic stability simulations of power systems.

Efficient Simulation of Line and Transformer Outages in Power Systems

Abstract: A method of simulating single and multiple transmission element (line and transformer) outages is discussed in the paper. The method simulates the outaged system states assuming the scheduled demands of the end buses of the outaged elements are still met. Sensitivity relationships of power systems are used both to determine the required power injections into the end buses, and to determine the corresponding corrections to the phase angles and magnitudes of bus voltages. The proposed method has been applied to the 30-bus and 118-bus IEEE standard test systems. Relevant results are presented and discussed.

Transient Stability and Long-Term Dynamics Unified

Abstract: A digital computer program is described for the accurate, economic simulation of both the long-term and short-term dynamic response of an interconnected power system. The EPRI Transient/Mid-term Stability power system. The EPRI Transient/Mid-term Stability Program was enhanced to allow a long-term operating mode where integration steps out to one second can be used. The program automatically reverts to and from the short-term and long-term modes according to the short-term and long-term modes according to prevailing system conditions.

Digital Simulation of Static Var System Transients

Abstract: This paper describes digital simulation of stAtic AR system transients. Methods are described for simultaneous digital simulation of thyristors, their gate pulse generating circuit, the regulating circuit, and the power system. Results are presented showing a voltage regulator's response to voltage changes and faults.

Simulation of a Multiprocessor Network for Power System Problems

Abstract: A network of computers arranged in a modified ring structure has been designed for solving in parallel the equations describing dynamic disturbances on large power systems. The operation of this network when solving a 1732-bus, 398-generator system using an algorithm based on the Bonneville Power Administration's Transient Stability Program has been simulated on a CDC 6600. The purpose of the simulation was to determine how efficiently the algorithm can be executed in parallel on this multiprocessor configuration. The critical part of the algorithm is the forward and back substitution passes through the LDU decomposed I = YE equations. Parallel execution times for various combinations of processors and the corresponding gains over a conventional serial solution are given.

High-Speed Power Flows Using Attached Scientific ("Array") Processors

Abstract: The array processor is a comparatively recent innovation in computer architecture which promises large amounts of inexpensive computing power on fairly large problems. In particular, it is able to handle problems involving large, sparse matrix manipulations without serious degradation in performance. One such problem is the AC Power Flow simulation. This paper describes the implementation of Stott's Fast Decoupled Power Flow algorithm on the Floating Point Systems AP-120B array processor. The goal is a power flow which will solve a 1000-bus problem in less than 0.5 second from a "flat start". The parallelism afforded by the functional units of the AP- 120B have a pronounced effect on how the algorithm is implemented. The sparse linear equation solver dictates the hardware options with which the AP-120B should be equipped.

An Optimal Control Law by Eigenvalue Assignment for Improved Dynamic Stability in Power Systems

Abstract: Whenever control laws are computed on the basis of linear optimal control theory and implemented on non-linear systems, such as power systems, the performance is not as good as expected because of saturation type non-linearities in the system components. The only way to ensure that a control law is adequate, short of actually testing the real system, is to observe the simulated behavior of the system. Departure between a calculated linear control law and the actual response can be minimized by (a) computing a feedback control law with gains of small magnitudes to achieve a pre-assigned set of eigenvalues for the closed loop system and by (b) judicious assignment of the eigenvalues to be achieved. This paper discusses a method for achieving such a control law.

A New Technique for Simulating the Operation of Multiple Assigned-Energy Generating Units Suitable for Use in Generation System Expansion Planning Models

Abstract: A new technique is presented for probabilistically simulating the operation of power systems which includes multiple assigned-energy units (e.g., conventional hydroelectric and, under certain circumstances, both nuclear units and cogeneration units). Within the context of probabilistic simulation, the new technique is completely rigorous. Statistical cumulants are used to represent equivalent load. The new technique has been successfully applied in an advanced technology evaluation and expansion model???the TVA TARANTULA model. This application has been accomplished with-out sacrificing other simulation capabilities such as: random partial outages, maintenance based on LOLP and load forecast uncertainty, and the ability to aggregate (without loss of rigor) groups of many small units for the purpose of computational expediency. A description is provided of tests performed to evaluate the new technique. Probabilistic simulation is a load duration oriented technique for simulating the operation of electric power systems. The technique is particularly amenable both to power systems consisting entirely of demand-energy units and to rigorous simulation of the random forced outage effects of these units. In this paper a demand-energy unit is defined as any generating unit which serves consumer load upon demand???provided the unit is available to do so and the dispatcher calls on it to operate. Demand-energy units include coalfired units, oil-fired units, gas turbines, and nuclear units early in the refueling cycle. Certain types of generating resources are unable to serve load upon demand (even if they are available to do so) because the supply of energy is limited.

Dynamic Simulation of a Power System Network for Dispatcher Training

Abstract: This paper describes the various requirements, problems and solutions in order to realize a power system network dynamic simulator for dispatcher training. Especially software techniques such as simulation algorithm and modelling are stressed. The description is based upon the experience gained in developing and implementing the simulator at the Power Control Center (PCC) of the Chubu Electric Power Co. (CEPCO), Japan. The simulator has been in operation since June 1981 in conjunction with the Automatic Dispatching System (ADS) at the PCC of CEPCO. To give trainees realistic simulation, the simulator calculates AC load flows and frequencies of a 287 node network every 5 seconds.

Power system simulation of low orbit spacecraft: The eblos computer programme

Abstract: This paper describes one approach to model spacecraft power systems. Modelling of solar array, batteries and power conditioning units is achieved for the simulation and analysis of in-flight performances of satellite power systems. The programme EBLOS operates from a minicomputer and at present deals with heliosynchronous orbits. However, for a maximum of flexibility, its design has been based on two features: a modular structure copied on the natural structure of power system and a nodal description input. The outputs are given in a form compatible with real in-flight measurements. The programme is described and validated against the ERS-1 Project.

An Accurate Computer Method for Obtaining Boundary Conditions in Faulted Power Systems

Abstract: This paper details an accurate technique to solve the three-phase power system equations under faulted conditions. The technique makes use of frequency domain simulation to provide a means of representing the transmission line with frequency dependent parameters. Faults can be simulated at any location along the line and at any time of fault inception. The technique enables a more accurate representation of synchronous machines to be combined with a transmission line model having distributed frequency dependent parameters. A typical power system example along with the modeling details illustrate the practicality and accuracy of the method.

A Local Control Strategy For Power Systems in Transient Emergency State Part I: Functional Design

Abstract: This paper is concerned with the investigation of a systematic corrective control approach for the transient emergency state problem of the power system. The proposed new control framework involves distributing the task of system transient stability margin improvement among several local facilities dedicated to the various subsystems comprising the power system. The functional design of the various local controllers to undertake local information processing and provide appropriate closed-loop stabilizing control action during severe transient disturbance is presented. An illustrative example is included to demonstrate the effectiveness of the proposed local control framework.

An Efficient Method for Real-Time Simulation of Large Power System Distribances

Abstract: This paper describes a method capable of simulating, interactively and in real time, the dynamic behaviour of a power system under emergency conditions. The method has been developed as a suitable basis for a digital simulator for use in training operators to deal effectively with severe disturbances.

Power System State Estimation: A Method for Metering Reinforcement

Abstract: This paper presents a modified-version of the Levenberg-Marquardt algorithm to overcome the ill-conditioning problem due to poor metering strategy in power system state estimation. The aim is to obviate the ill-condition permanently by high-lighting the most sensitive points where additional meterings are necessary. Digital simulation results are presented on an ill-conditioned metering structured power system. The algorithm can be extended to cover the case of preventing estimator failure due to telecommunication breakdown.

A Generalized Methodology for Modeling System Components in Power System Dynamics Simulation

Abstract: A generalized methodology for modeling various system components in power system dynamics simulation studies is presented in this paper. One of the salient features of the method is its applicability to transient stability, mid-term dynamics simulation and long-term dynamics simulation. Also, the application of sparse matrix techniques to the computation of initial conditions is presented.

A Local Control Strategy for Power Systems in Transient Emergency State. Part II: Implementation and Test Results by Simulation

Abstract: The functional design of a local control strategy considered suitable for bulk power system disturbed into transient emergency state was set forth in the companion paper [1]. It utilized a particular control procedure based on an adaptively specified angle- velocity threshold limit criteria. In order to consolidate the validity of the strategy, this paper describes its algorithmic implementation and discusses two extensive test results. The design philosophy and implementation of the proposed control framework are based on the hierachical control approach.

Simulating Central Battery Storage Using A Levelized Incremental Cost Method

Abstract: This paper describes a methodology for including central battery storage in hourly production simulation computer programs. As such, these simulation tools calculate detailed production statistics by modeling the hour by hour operation of a power system over the planning horizon. An example of such a production analysis code is GLIMPS, described in reference 1-2. By integrating the hourly operation of central storage into the unit commitment and economic dispatch routines, production analysis codes can be used to assess the production credits associated with the storage technologies. These credits can then be used to value central storage by determining the present worth production costs with and without storage over the planning horizon.

Design of A Generalized Static-Var System Model For TNA Simulation

Abstract: The development of a generalized static-var system (SVS) model for transient network analyzer (TNA) simulation is described in this paper. The development included the design of a real-time, programmable micro-processor control which allows convenient analysis of any control system characteristics. The hardware was designed so that a wide variety of static-var system configurations could be represented. Control of the static-var system model by the master TNA control computer is also described and an example of the data output is presented.

Power Distribution Planning and the Application of Linear Mixed-Integer Programming

Abstract: The planning of power distribution networks is a complex process in which the application of mathematical models and optimization methods has grown considerably in the recent few years A survey of problems in connection with the synthesis of distribution networks is given The planning process is analyzed and computer application in special areas is discussed A fundamental task is the selection of a suitable mathematical optimization technique The main characteristics of models for distribution planning are decisive for this purpose A comparison of properties and abilities of various optimization techniques reveals the advantages of linear mixed-integer programming For this efficient algorithms based on the branch-and-bound principle are available as standard program products [1] The method is not suited economically for arbitrary distribution planning problems A severe problem selection and an exact problem formulation are re- commendable Modelling techniques influence heavily solution time and therefore a short overview is given An example in the appendix illustrates the application on a typical problem

Dispatcher Training Course: Program, Facilities, and Support Requirements

Abstract: A Dispatcher Training Course was developed with the main objective being to educate power system dispatchers in the fundamental principles and practices of interconnected system operation and performance.

Simulation of electric power systems by parallel computation

Abstract: The aim of dynamic contingency calculations in power systems is to estimate the effects of assumed disturbances, such as loss of generation, faults, etc. Due to the large dimensions of the problem these simulations require considerable computing time and cost, which may be reduced by parallel computation. Some results of a study employing a prototype parallel computer (SMS) are presented. It presently consists of a bank of 16 microcomputers bus-connected to a process computer Siemens 330-R30. Each of the modules is programmed to simulate a node of the power grid. Generators with their associated control are represented by models of 13 states. All programming is performed through the control computer in FORTRAN. 10 references.

Dynamic Programming in Power System Extension Planning

Abstract: In connection with questions concerning generation extension planning a model for extension optimization of power systems was established in 1973. Thereby the particular situation of Austria characterized by a high hydro proportion had to be taken into account. The model shall serve two purposes: first adequate additions of hydro and thermal power plants shall be determined and second design problems, such as reservoir volumes for pondage and annual storage power plants.

Optimal stochastic scheduling of power systems with delays and large cost differentials

Abstract: The optimal scheduling or unit commitment of power generation systems to meet a random demand involves the solution of a class of dynamic programming inequalities for the optimal cost and control law. We study the behavior of this optimality system in terms of two parameters: (i) a scheduling delay, e.g., the startup time of a generation unit; and (ii) the relative magnitudes of the costs (operating or starting) of different units. In the first case we show that under reasonable assumptions the optimality system has a solution for all values of the delay, and, as the delay approaches zero, that the solutions converge uniformly to those of the corresponding system with no delays. In the second case we show that as the cost of operating or starting a given machine increases relative to the costs of the other machines, there is a point beyond which the expensive machine is not used, except in extreme situations. We give a formula for the relative costs that characterize this point. Moreover, we show that as the relative cost of the expensive machine goes to infinity that the optimal cost of the system including the expensive machine approaches the optimal cost of the system without the machine.