Showing papers on "Electric power system published in 1979"

IEEE Reliability Test System

Abstract: This report describes a load model, generation system, and transmission network which can be used to test or compare methods for reliability analysis of power systems. The objective is to define a system sufficiently broad to provide a basis for reporting on analysis methods for combined generation/transmission (composite) reliability.

Linear Programming for Power-System Network Security Applications

Abstract: A linear programming (LP) method for security dispatch and emergency control calculations on large power systems is presented. The method is reliable, fast, flexible, easy to program, and requires little computer storage. It works directly with the normal power-system variables and limits, and incorporates the usual sparse matrix techniques. An important feature of the method is that it handles multi-segment generator cost curves neatly and efficiently.

Reliability modeling in electric power systems

Abstract: (1979). Reliability Modeling in Electric Power Systems. Journal of the Operational Research Society: Vol. 30, No. 8, pp. 769-769.

Power system dynamic response calculations

Abstract: Engineers in the power industry, face the problem that, while stability is increasingly a limiting factor in secure system operation, the simulation of system dynamic response is grossly overburdening on present-day digital computing resources. Each individual response case involves the step-by-step numerical solution in the time domain of perhaps thousands of nonlinear differential-algebraic equations, at a cost of up to several thousand dollars. A high premium is thus to be placed on the use of the most efficient and reliable modern calculation techniques. This paper is a critical tutorial-review of the calculation methods used routinely or investigated for use by the industry. It concentrates on solution concepts and computational techniques rather than on the analysis of the numerical methods. Details of system modeling are only emphasized when they affect the choice of solution method. The paper concludes with a view of the state of the art and a prediction of future directions of development.

Real-Time External Equivalents for Static Security Analysis

Abstract: Equivalent models for the external system in online load-flow studies are presented. The main contribution is a simple extension to the Ward-type equivalencing method that solves the boundary-bus designation problem and gives reliable and accurate results. The method can be applied equally well for off-line equivalencing, where it overcomes the need for buffer zones. Variations on this technique are investigated. The models require topology information, but no real-time measurement data, for the external system. The new methods have been verified by simulation on the IEEE 30 and 118 bus load-flow test systems and on the 835-bus interconnected 15 GW power system of S.E. Brazil.

Statistical synthesis of power system functional load models

Abstract: Functional load models characterize the load demand portion of a component load when the influence factors are weather, and human use patterns, etc. Physically based functional load models for individual components are proposed. From these the functional load model of a large number of similar components is obtained by statistical aggregation.

Economic criteria for optimizing power system reliability levels

Abstract: A generalized simulation model for optimizing the reliability level of electrical supply is described. The model is applied to a case study of Cascavel, Brazil to determine a range of optimum reliability levels for long range electric power distribution system planning. The basis of the model is its comparison of the social benefits and costs of changes in power system reliability. The supply side costs of increasing system reliability can be determined from straight forward engineering considerations. On the demand side, the benefits of electricity users consist of cost savings from averted power failures or outages, which may be measured by the disruption of the output streams owing to idle input factors and spoilage. The results of the Cascavel case study indicate that the principal outage costs are incurred by industrial and residential consumers. This fact is reflected in the optimum design of the distribution system, with the high population density core city area and the industrial zone receiving the most reliable service. 22 references.

Power System Analysis

Abstract: Sinusoidal Steady State Circuit Concepts. Power System Representation. Transmission Lines. The Power Transformer. The Synchronous Machines. The Power Flow Problem. Operation and Control of Power Systems. Balanced and Unbalanced Faults. Fault Analysis by Computer Methods. Power System Protection. Power System Dynamic Performance. Appendices. Index.

Diagnosing Power Quality-Related Computer Problems

Abstract: Total reliance on sensitive electronic systems for such important functions as data processing, communications, and process control is now a way of life in our commercial, industrial, and governmental activities. This development has necessitated a new concern toward the quality of the electric power supply. Intermittent power disturbances, capable of disrupting electronic equipment are inherent to both commercial and industrial power systems. Any disruption causing downtime and financial loss, power-related or otherwise, is likely to precipitate a study to determine appropriate corrective actions. Unfortunately, analyzing the cause and effect of power disturbances can be difficult, particularly when sophisticated computer systems are involved. The ultimate purpose is to assist the electronic equipment users in reducing power-related downtime.

Supplemental electrical power generating system

Abstract: Hydrocarbon fuel energy is converted to AC electrical energy by a new system utilized to supplement AC power for household and similar limited size loads in synchronism with existing AC utility service via pre-existing wiring between the load and the utility lines. The system has an externally excited commutator AC motor-generator driven by an internal combustion engine to provide AC power at a magnitude which is a function of the drive shaft velocity and degree of excitation. An exciter circuit provides excitation for the motor-generator to cause the generated AC power to be in phase with utility power. A load demand sensor senses current flowing through the wiring to the load, providing a control signal signifying magnitude of the current, thus measuring load power requirements. Control circuitry interconnected with the exciter circuitry and the engine is responsive to the control signal to control excitation for causing the generated supplemental power substantially to meet load requirements. The control circuitry also controls engine speed to provide sufficient engine power to meet these load requirements. Mechanical elements of the system are contained by an insulated, sound-proofed enclosure. Air is drawn into the enclosure for cooling of the motor-generator and for recovering heat from the engine and the engine exhaust. The heated air is ducted out of the housing for use in household heating, etc. Various circuit features, including a phase sensitive detector, ensure that electrical power generated by the system does not flow back to the utility service. The system starts and stops automatically according to power demand.

Load-flow studies in the presence of geomagnetically-induced currents.

Abstract: Large transient fluctuations in the earth's magnetic field can produce quasi-dc currents in electric power systems. These geomagnetically-induced currents (GIC's) cause half-cycle saturation in power transformers resulting in increased transformer var requirements. This paper discusses the phenomena by which GIC's are produced in power systems, the system and transformer modeling necessary for representing the effects, and the results of load-flow studies made with GIC present in a large interconnected power system in the northern United States and Canada. Results of the studies are compared with data recorded during a geomagnetic storm.

System and method for accelerating and sequencing industrial gas turbine apparatus and gas turbine electric power plants preferably with a digital computer control system

Abstract: A gas turbine power plant is provided with an industrial gas turbine which drives a rotating brushless exciter generator coupled to a power system through a breaker. One or more of the turbine-generator plants are operated by a hybrid digital computer control system during sequenced startup, synchronizing, load, and shutdown operations. The program system for the computer and external analog circuitry operate in a multiple gas turbine control loop arrangement. Logic macro instructions are employed in programming the computer for logic operations of the control system.

Load Supplying Capability of Generation-Transmission Networks

Abstract: This paper describes an extension of the power transfer capacity calculation to the calculation of maximum power system loading. This loading capability is a function of the generation and transmission capacity of the power system. The dc power flow equations provide a basis for the development of constraint equations necessary in the linear programming optimization of the generation-transmission system. An example is provided to illustrate the concepts of the load supplying capability of the power system, and the application to assessment of network adequacy and long range planning is discussed.

Optical Measurement of Current and Voltage on Power Systems

Abstract: The basic principles of optical methods for measuring voltage and current at high voltage are presented. These include the magneto-optic effect, the electro-optic effect and the electrogyration effect, plus various detection and noise-reduction techniques. Both free-path and enclosed-path devices which have been constructed on these principles are described. The viability of these devices for the electricity-supply industry is assessed.

Modelling and Evaluating the Reliability of Distribution Systems

Abstract: Comparatively, distribution systems have received least consideration in the reliability evaluation of power systems although paradoxically they have the greatest average effect on loss of supply to the consumers. This paper discusses the inherent features of typical distribution systems and describes and evaluates models that more truly reflect the operational behaviour of such systems and their effect on the consumers. The analysis of a typical system is included which illustrates the additional and more meaningful results that can be achieved from the use of these improved system models.

Near-optimal control of composite systems: The multi time-scale approach

Abstract: This short note formulates an m -level hierarchical system structure, with the lower level subsystems being faster than the one above. In the context of linear time-invariant systems and the regulator problem a near-optimal solution is found using results in singular perturbation theory. An example from power systems is given, and computational and conceptual advantages of the method are indicated.

Frequency adaptive, power-energy re-scheduler

Abstract: A frequency adaptive, power-energy re-scheduler (FAPER) that includes a frequency transducer that notes frequency or frequency deviations of an electrical system and logic means which controls and re-schedules power flow to a load unit in part on the basis of the deviations in frequency from a nominal frequency and in part on the needs to the load unit as expressed by an external sensor signal obtained from the physical system affected by the load unit

Harmonic Analysis and Suppression for Electrical Systems Supplying Static Power Converters and Other Nonlinear Loads

Abstract: This paper is comprised of the proposed Chapter 9, entitled ``Harmonic Analysis,'' of the forthcoming IEEE Recommended Practice for Industrial and Commercial Power System Analysis (Brown Book).

Model of generator saturation for use in power-system studies

Abstract: The representation of magnetic saturation of generators in power system studies is re-examined in the light of new test data obtained on 500 MW and 660 MW units. A new saturation model, of adequate simplicity for use in multi-machine studies, is formulated and checked for accuracy. The parameters for use in the model are obtained firstly from no-load measurements but later in the paper it is shown that the parameters can be obtained from on-load measurements. The primary incentive for the work was to devise a method for the accurate calculation of generator rotor angle when operating at leading power factors. In the event, the model is shown to produce accurate calculation of both rotor angle and excitation requirements over the whole of the normal operating range.

Charging Current Data for Guesswork-Free Design of High-Resistance Grounded Systems

Abstract: The design of high-resistance grounded power systems requires the sizing of the grounding resistor to provide a current flow equal to or greater than three times the system charging current (I co ) of each phase. In industrial power systems the insulated power cables are a major source of system charging current which flows into line-to-ground faults. Data are presented which will allow cable charging currents to be quickly and precisely determined after the cable size, voltage, footage, insulation type, and thickness have been determined. Charging current data for transformers, motors, generators, and capacitors are also included.

Induction-generator/synchronous-condenser system for wind-turbine power

Abstract: A novel wind-turbine-driven electric power system for isolated communities is described. The system components consist of an induction generator and a synchronous condenser. The synchronous condenser supplies the magnetisation current to the induction generator. Besides supplying the load power, the induction generator feeds the synchronous condenser with real power to replenish windage, friction and I2R losses to sustain it at synchronous speed. The theory of operation is given, and predictions based on it are experimentally verified. The controllers required to maintain regulated voltage and frequency in spite of load and wind velocity changes are investigated. Slip-energy recovery is involved, and preliminary test results are presented.

Current Transformer Burden and Saturation

Abstract: A tutorial review of the steady-state and transient behavior of current transformers used with power system relays and meters is presented. ANSI accuracy standards are discussed and consideration is given to the significance of burden and saturation in the application of protective relays.

30-MJ superconducting magnetic energy storage (SMES) unit for stabilizing an electric transmission system

Abstract: Electric power systems that have major loads and generation centers separated by large distances may experience low-frequency power oscillations. This type of oscillation has occurred on the Pacific AC Intertie that connects southern California and the Pacific Northwest. A separate, almost parallel, dc-transmission line also connects these areas. The Bonneville Power Administration, which operates this transmission system, has overcome the instability by controlling the power transmitted on the dc-transmission line. A 30-MJ (8.4-kWh) superconducting magnetic energy storage unit with a 10-MW converter could also provide damping for this instability. The conceptual design of the 30-MJ coil and the cryogenic and electrical components of the system are described. The system is to operate at a maximum current of 5 kA and will modulate the AC Intertie at 0.35 Hz. Discharge will be controlled to retain a minimum stored energy of 20 MJ to limit cyclic strains in the coil and ac losses in the conductor. The conductor will be made of multistrand-copper and copper-matrix, multifilament NbTi superconducting wires on a stainless steel mandrel.

Current sharing modular power system

Abstract: A current sharing modular power system including, in each module, an inverter circuit and means to determine the current to a common load from the module. A difference circuit is provided to determine the difference between the module supplied current and the average of the current supplied by the other modules. The difference is then utilized to vary the pulse width of the inverter output so that the pulses are wider if the current from the module is smaller than the current supplied by the other modules and the pulses are thinner if the current from the module is larger than the average current supplied by the other modules. The system also includes a voltage sense circuit to adjust the module operation to maintain a constant voltage output.

Dual speed control circuit for power flow through an inverter

Abstract: A control circuit for a force-commutated inverter connected intermediate a regenerative DC power source and a power grid, the power source/inverter combination operative to supply AC electrical energy to, or receive AC electrical energy from or adjust the power factor of, the AC electrical energy of the power grid. The control circuit of the present invention varies the real power component and the reactive power component of the electrical energy flowing between the electrochemical cell and the power grid through the use of two feedback loops with separate time constants. The first feedback loop allows for the independent control of the magnitude and direction of both the real power component and the reactive power component of the AC electrical energy flowing to or from the power grid. The first feedback loop also has a relatively slow time constant so that the power flow between the DC source and the power grid is substantially unaffected by transients. The second feedback loop has a fast time constant for rapidly adjusting the effective magnitude and phase of the voltage waveform from the inverter to compensate for instantaneous or short duration voltage surges which periodically appear on the power grid.

Estimation Algorithms for Large-Scale Power Systems

Abstract: The operation of large-scale power systems demands that the real-time monitoring, security, and control procedures can draw on a consistent and reliable set of data representing the measurements and the network parameters. This paper considers the enhancement of this data base through advanced estimation programs for the states and parameters of the network. The role of such programs and the different forms they can take are presented in a comprehensive and unified manner. This will assist the designer in the task of selection and development of a suitable algorithm for his system from a set of possible approaches.

Dual alternator power system for motor vehicle

Abstract: In an emergency vehicle having dual batteries, one of which is employed for supplying power to the electrical system of the vehicle chassis and the other of which is employed for supplying power to the emergency equipment, dual alternators driven by the engine are provided for charging the batteries. The output of each alternator is connected to the input of its regulator and to both batteries whereby both alternators will be on at all times when the engine is running and will share the load on either or both batteries.