Showing papers on "Electrical network published in 1983"

A New Planning Model for Distribution Systems

Abstract: This work presents an efficient algorithm for the static investment planning of large radial distribution systems. It takes into account the fixed costs, concave nonlinearities in the cost functions of all elements and the operational constraints. A concave fixed cost model is used to represent elements with large fixed costs (substations and possibly some feeders) and linear cost functions are assumed for the remaining elements. A branch and bound algorithm is used with bounding criteria dependent on the cost and operational constraints. The fixed costs of the remaining elements is then accounted for through an iterative procedure which modifies the solution of the first step. The validity and efficiency of the model have been tested against published results. Results for a large rural radial system are presented.

Transmission Network Equivalents for Electromagnetic Transients Studies

Abstract: In electromagnetic transients studies, only a limited part of a transmission system can be modelled in detail. The remaining parts of the system have to be reduced to equivalents. Simple equivalents which reproduce the network's response at few frequency points can introduce significant errors into the calculated transients. A method to generate network equivalents from the frequency response of its admittance has been developed. The equivalents are in the form of lumped parameter circuits, have a simple structure and reproduce the network's behaviour over a wide frequency range. The developed method was used to generate an equivalent for a sample system. Voltage transients due to an energization of a transmission line from that sample system were calculated. The results of calculations with the full system representation and the developed equivalent showed a good agreement.

Control apparatus with improved structure for cooling circuit elements

Abstract: A control apparatus such as an inverter includes a hollow body having generally a rectangular cross-section, composed of sides of sheet metal with upper and lower open ends shielded by cast hollow frames, each having a similar cross-section. Electrical circuit elements are mounted to one of the sides of the hollow body through an opening therein. Ventilating fans are mounted to at least one of the hollow frames for cooling the electrical circuit elements.

Design Of The Measurement System For State Estimation In The Norwegian High-Voltage Transmission Network

Abstract: A method proposed by Koglin has been used to find an optimal measurement system for static state estimation in the Norwegian high-voltage transmission network. The method is extended in order to obtain a more robust solution in situations with loss of measurements and bad data, and to reduce the computational effort required. The significance of choice of estimation method, load flow situation and network topology is discussed. In addition the optimal measurement system has been compared with manually designed and arbitrarily generated systems.

Large Scale Security Dispatching: an Exact Model

Abstract: An exact optimal power flow model is presented for dispatching generation, transformer taps, and generator voltages to minimize operating costs while guaranteeing a steady state secure operating point after a contingency. A full ac power flow model is used, which permits including voltage and reactive power constraints in the optimization. The technique of this paper is unique in that all of the voltage and power constraints of all selected contingencies are enforced in a single optimization. No cycling between contingency evaluation and optimization is necessary in order to update the list of active constraints. Cases which have divergent power flow solutions are included in the problem with no difficulty. All non-islanding outages are guaranteed to converge to a feasible solution. The optimization algorithm solves a sequence of linearly constrained subproblems using a quasi-Newton search direction. The dispatching algorithm is tested on the IEEE 118 bus system power system.

System for producing and distributing electrical energy for vehicles particularly aircraft, as well as an electrical power center for such a system

Abstract: In a system including an electrical power center for producing and distributing electrical energy for vehicles, particularly aircraft, primary circuit breakers and contactors are distributed between a D.C. electrical power center, relay boxes, electronic bays and control panels and the electrical power center forms a central unit grouping together different protection or safety devices. The system permits the electrical network on board an aircraft to be simplified and lightened.

Assessment of Electrical Energy Losses in the Colombian Power System

Abstract: The electrical energy losses for the entire Colombian power network comprising distribution voltage levels up to the high voltage transmission levels are calculated. The energy losses are classified as "physical" losses corresponding to Joule effect-(I2R), Corona and core transformer losses and "black"-losses which are defined as the difference between the energy available at the consumer level and the energy- effectively billed by the different electric utilities in Colombia. A new methedology for calculating the-"physical" losses is presented which is extensively ba sed in the use of computerized methods including state estimation for the high voltage network and radial load flow for the distribution levels. The "black" losses ses including metering errors, theft and billing errors are calculated with statistical methods also using computerized tools. The results obtained highlight-the importance of the losses in terms of loss of revenue for the electrical energy utilities.

Timed gas metering and distribution system

Abstract: A timed gas metering and distribution system provides a point of use metering and an individual remote meter readout capability in a branched-line gas distribution system, such as in a multi-unit apartment building. In such a system, a single main gas line enters the building and has branches of minimal length extending to a gas-fueled appliance, e.g., a heater, in each unit. Each heater has a fixed orifice in its gas line, to provide a specified fixed gas flow rate at a constant line pressure and an electrical pressure switch in its manifold to detect pressure changes and actuate an electrical circuit upon operation of the heater. The circuit transmits an electrical signal to a timing meter located remotely of the unit for convenient reading. One embodiment uses a direct current electrical circuit and a digitally controlled analog run-time meter. A second embodiment uses an oscillator low frequency pulsing circuit, shift register, and digital counter. It can be used to monitor gas consumption of multiple appliances by summing the pulse trains. As used in a fixed flow appliance, the pulsing circuit uses a mechanically tunable oscillator to proportion the pulse rates to constant pressure gas flow through a fixed orifice. For a variable flow appliance, e.g., a stove, a voltage-tunable oscillator, controlled by a switch-potentiometer coupled to the gas flow control, proportions the pulse rate to gas flow.

Loop fault isolator

Abstract: The invention comprises a method and a device for locating, isolating and by-passing a defective electrical device in an electrical circuit, and comprising sensing current and voltage at a first point in such circuit, on one side of such device, whereby the current and voltage are not significantly altered by the sensing process, sensing current and voltage at a second point in such circuit, on the other side of such device, whereby the current and voltage are not significantly altered by the sensing process, comparing such currents and voltages as between such two points, creating a control signal responsive to such compared currents and voltages, and, isolating such device from such circuit, and thereafter re-establishing such circuit whereby to by-pass such device, in response to a control signal of predetermined characteristics.

Electrical circuit assembly

Abstract: The invention describes a method of producing an electrical circuit incorporating integrated circuits on semiconductor chips, which comprises mounting the electrical components (10) which are to constitute the circuit including the unpackaged semiconductor chips on an insulating substrate (12) in such a manner that the contact areas 14 of the components lie in a substantially flat plane, and depositing a conductive pattern over the substrate to establish electrical connection between the components of the circuit.

Microprocessor-based identification system applied to synchronous generators with voltage regulators

Abstract: With the need to improve the operation and control of existing generating units and to provide accurate information for the design of new units, better transfer function models and estimates of system parameters are required. This involves the identification of individual generator and voltage regulator parameters as well as system modes of oscillation and damping. The problem is to experimentally determine this information, simply, quickly and accurately. For this reason, system identification techniques are of interest to power engineers. In the paper, an identification technique involving pseudo-random ternary noise injection and cross correlation is assessed and applied to power systems. The theoretical basis, advantages and limitations of this method are examined and it is shown that the entire process of signal generation, injection, response measurement and crosscorrelation can be performed in real time using a dedicated microprocessor system. The identification technique is tested on a simple microalternator connected to a noisy power system through a transmission line. It is shown that under normal operating conditions a highly accurate system impulse response can be obtained and that the parameters of the machine and its voltage regulator can be estimated from this result. The technique is also applied to an open-circuited microalternator with a more complex voltage regulator and estimates of the regulator parameters are found with good accuracy.

Dynamic Equivalent Power System Models

Abstract: This paper discribes the use of identification methods for the determination of dynamic equivalent models of portions of a power system. The resulting models are linear models for use in stabilizer design and dynamic stability studies. Data for the models are obtained from a transient stability program where small perturbations of the complex voltage on a bus are made, and the resulting complex currents are measured. Using the above data and linear system identification techniques, linear models are obtained relating the complex current to the complex voltage on the bus. The power system as seen from the bus may then be replaced by the model. An example system of 59 machines and 63 buses is used to demonstrate the method[l].

Representation and analysis of electrical circuits in a deductive system

Abstract: We have developed representations and analysis methods for electrical circuits in a deductive system called DUCK. Circuitsare represented as conjunctions of logical predicates. Circuit analysis is done as an iteration of proofs which determine the basic structures in the circuit. Electrical constraints for the circuit are produced from the results of the proofs. The constraints are then solved using propagation methods.

Electrical Phenomena in Fish Intestine

Abstract: This article is an attempt to review electrical phenomena in fish intestinal preparations. In the first two sections the various preparations and their electrical characteristics will be described. In the next section, the equivalent electrical circuit and a geometrical representation of the equations used as a solution of the equivalent circuit as introduced by Bakker (1980) will be presented. Then the electrical characteristics will be discussed on the basis of the equivalent circuit and the question of an active CI- transport in seawater fish will be debated. The final section will deal with sugar-and amino acid-evoked potentials.

Reactive Power Dispatching for Power System Voltage Security

Abstract: An optimization-based method is presented for determining the scheduling of reactive equipment (capacitors for example) on an hourly basis for maximum steady-state power system security during normal and post-contingency conditions. The method simultaneously deals with the effects of a number of contingencies, and includes all bus voltages as constraints. The intended application is to schedule existing capacitors during periods of light load to prevent abnormally high voltages from occurring during normal and post-contingency condittons. Results from tests using a Pennsylvania-New Jersey-Maryland Interconnection (PJM) model are presented.

RF Conducted noise measurements of automotive electrical and electronic devices using artificial network

Abstract: Two RF conducted noise measurement systems have been developed for laboratory measurements of automotive electrical and electronic devices. One is a noise emission measurement system for measuring noise level from the electrical devices while the other is a susceptibility measurement system for measuring the susceptibility level of the electronic devices to the noise. The former's function is to measure a histogram of noise level, and the latter functions both to measure the malfunction level and to judge a malfunction mode of the electronic devices. These measurement systems are applicable to the frequency of 150 kHz-60 MHz. These are for laboratory measurements performed with the measurement systems connected to an artificial network of the automotive electrical network. This artificial network represents electrical networks used on Japanese compact passenger vehicles.

A Frequency Response Method for Determining the Parameters of High-Performance DC Motors

Abstract: This paper introduces a technique for measuring the parameters of high-performance dc motors. A second-order motor model, under certain conditions, is shown to be equivalent to a series resonant electrical circuit. Frequency response measurements of the motor, when treated as an electrical impedance, form the basis of a measurement technique which has certain practical advantages. Results are compared to measurements made using conventional methods.

Sensor with optically excited resonant circuit

Abstract: A sensor (9) for detecting or measuring quantities such as position, force, pressure, liquid level, flow, temperature, voltage, current and magnetic field, which comprises opto- electric members for converting optical energy into electric energy and vice versa is characterised in that at least one electrical resonant circuit, the resonant frequency or Q-value of which is arranged to be influenced by the quantity to be detected or measured is included in the electrical circuit of said opto-electric members. As shown, the sensor enables conversion of an electrical pulse input 8, derived from a phase locked loop 13, to a ringing electrical output from 10 which is fed to the phase comparator 14 of the loop 14. The branch 7 of optical fibre coupler 5 may be further divided for simultaneous use of a plurality of sensors with different resonant frequencies. Light emitting and photo diodes 8 and 10 may be replaced by a single diode performing both functions.

Reliability and Availability Studies for Industrial Power System Analysis

Abstract: Reliability and availability (R&A) studies have been made a part of the IEEE Recommended Practice For Industrial and Commercial Power System Analysis (IEEE Standard 399-1980). R&A studies should improve the selection of system configurations and components by basing decisions on quantitative information rather than on intuitive and qualitative decisions. The R&A indices for any electric power system design can be computed from knowledge of the statistical performance of individual components within the system. One of the important indices is the system overall downtime, which has a direct cost impact due to plant process interruption. In addition to R&A computation of electrical components in simple series or parallel configurations, other commonly encountered electrical power systems situations are considered such as a) scheduled maintenance of system components, b) manual switching of system components, c) transformer overloading practices, d) parallel redundant connections within a system, e) spare components available on short notice, and f) local generator units. These situations will be discussed, and the methods of calculation required to include them in R&A studies will be presented.

LINSIM, a Linear Electrical Network Simulation and Optimisation Program

Abstract: On-line computer-aided-design programs must be versatile, easy to use, reliable, and virtually ‘crash-proof. LINSIM is such a package which has been used by students and engineers at the University of Canterbury, New Zealand, for the past three years. Its structure and use are described and illustrated.

Photo trigger type solid-state relay

Abstract: PURPOSE:To prevent the damage of element and malfunction due to noise, by insulating terminals inbetween perfectly in DC and AC electrical circuits by using a photo-electric conversion circuit including an optical fiber and a photodetector. CONSTITUTION:An output signal of a microprocessor is converted into a light as an input and it is converted into an electric signal at a photo-electric conversion circuit consisting of an optical fiber 14C, a fiber connector 14A, a visual light cut filter 14B and a photodetector 4B, a signal is formed at a zero voltage detector 3, a bidirectional thyristor 1 is triggered via a signal amplifier circuit 2, and a series circuit consisting of an AC power supply 30 and a load 20 is conducted. The DC low voltage side of the microcomputer and the AC side of the load 20 are completely isolated in the electrical circuits of DC and AC, allowing to avoid the damage of elements and malfunction due to noise.

Leaky Electricity: 1-Chain Formulas for the Current and Voltage

Abstract: A leaky electrical network N is a mathematical generalization of an electrical network. In this paper we present a formula expressing the current 1-chain of N as a linear combination of leaky $uv$-flows associated with the spanning 2-arborescences and a formula expressing the voltage 1-chain as a linear combination of coboundaries associated with the spanning 2-arborescences. This generalizes a result of Nerode and Shank [Amer. Math. Monthly, 68 (1961), pp. 244–247] on electrical networks.

Recent advances in variable speed electrical generator systems for large wind turbines

Abstract: Major variable speed electrical generator system design objectives have been verified through large-scale experiment. Full exploitation of variable speed generator benefits can revolutionize large wind turbine design. The greatest advantages come not only from the improved aerodynamic efficiency of keeping tip speed proportional to wind speed, but from dramatic reduction in drive train resonances, elimination of dissipative damping losses, easy motorized turbine start, and isolation of turbine dynamics from the electrical network. Experimental verification proceeded by two steps: first, actual control hardware and software were verified with a hybrid simulation of a full wind turbine system; then the controls were combined with power thyristor bridges configured as a cycloconverter and motor-generator test train to implement a variable speed generator and a simulated wind-turbine/drive train. Although the existing equipment presented several constraints on testing latitude, major features demonstrated include: (1) variable frequency motoring to 50% speed for quick, efficient turbine start-up; (2) synchronization below, at, and above synchronous speeds, both steady state and transient; (3) net power output up to 120 kW with stable response to 50 kW step changes in demand within one second and similarly responsive control of VARs; (4) steady power and VAR output throughout speed transients frommore » ten percent below to ten percent above synchronous speed; (5) output voltage waveform with less than five percent total harmonic distortion; and (6) damping of simulated drive train resonance at 0.2 Hz.« less

Cutting and separating tool for parts and connecting points made of plastic

Abstract: The cutting and separating tool for parts and connecting points made of plastic consists of an insulated handle and a tool blade which is located directly in an electrical circuit and is heated by virtue of its electrical resistance. The tool blade preferably used is an essentially U-shaped rigid bow, the leg ends of which are connected to the electrical terminals. This bow can be flattened in the shape of a blade at least in the front region and/or can be angled transversely to its main central plane. The tool blade is connected to an electrical voltage source of approximately 0.5 V-5 V and has a power of approximately 0.1-0.2 kW.

Switch, especially for cooling devices

Abstract: A switch especially for controlling a refrigerator which can equally be operated from an electric mains, a storage battery and a source of propane-butane gas, has a shaft 3,8 journalled in a housing 5 and provided with cams 1 for actuating electrical microswitches 6 which control the electrical circuits supplying the electrical power. In a given angular position of the shaft 3, it is axially movable for actuating a gas supply valve 4. The microswitches 6 are isolated from each other by partition walls of the housing 5.

A solution for an infinite electrical network arising from various physical phenomena

Abstract: A procedure for determining the currents and voltages in a square or cubic grounded grid, wherein the grounding conductances can differ in quite arbitrary ways, is presented. Such a semi-infinite electrical network is of practical importance, for it arises naturally from the discretization of a number of physical phenomena. There are very few classes of infinite electrical networks for which computational methods of solution exist; the present work adds one more class to that brief list.