Showing papers on "Voltage optimisation published in 1979"

Method for controlling power flow between an electrochemical cell and a power grid

Abstract: A method for controlling a force-commutated inverter coupled between an electrochemical cell and a power grid for adjusting the magnitude and direction of the electrical energy flowing therebetween. Both the real power component and the reactive power component of AC electrical energy flow can be independently varied through the switching waveform presented to the intermediately coupled inverter. A var error signal is derived from a comparison of a var command signal with a signal proportional to the actual reactive power circulating between the inverter and the power grid. This signal is presented to a voltage controller which essentially varies only the effective magnitude of the fundamental voltage waveform out of the inverter, thereby leaving the real power component substantially unaffected. In a similar manner, a power error signal is derived by a comparison of a power command signal with a signal proportional to the actual real power flowing between the electrochemical cell and the power grid. This signal is presented to a phase controller which varies only the phase of the fundamental component of the voltage waveform out of the inverter relative to that of the power grid and changes only the real power in proportion thereto, thus leaving the reactive power component substantially unaffected.

Rate sensing instantaneous trip mode network

Abstract: Air core current transformers respectively linked with the phase conductors of a power distribution circuit develop secondary voltage signals proportional to the rates of change of the phase currents. A full-wave rectifying network provides a rectified output voltage signal corresponding to the highest magnitude secondary voltage signal. A comparator issues a circuit breaker trip initiating signal when the output voltage signal achieves a pre-selected threshold voltage.

Metering and protection system for an A.C. power system

Abstract: A system for electronically metering an A.C. electrical power system to derive performance parameters such as real and reactive power useful in revenue metering and fault protection applications. Voltage and current sensors associated with the power system provide isolated output signals proportional to the voltage and current in the system. From these signals finite-duration impulse-response filters periodically determine Walsh function correlation coefficients by integrating the voltage and current signals at least once during each period of the power system and periodically sampling and holding the integrated signal in sequence with the integration. The present and a plurality of immediately preceding correlation coefficient values are stored in memory, and by combination of the correlation coefficients by addition, subtraction or multiplication, power system performance parameters, such as real power, reactive power, voltage, current, or power factor, are obtained for utilization in revenue metering or overload protection applications. Related methods are also disclosed.

Controlled D-C power supply

Abstract: By controlling the phase angle at which conduction occurs in the SCR's in an SCR rectifier bridge, a d-c voltage of adjustable magnitude may be produced from a-c line voltage applied to the bridge. The specific angle at which the SCR's are fired into conduction during each half cycle of the a-c line voltage is determined by comparing a ramp-shaped pulse, produced from the line voltage during each half cycle, with an error signal which varies as a function of the difference between the desired d-c magnitude and the actual amplitude of the d-c voltage. The d-c power supply is made immune to line voltage variations by regulating the ramp-shaped pulses so that they always have the same pulse width regardless of line voltage amplitude, thereby facilitating precise control over the d-c magnitude.

Voltage controlled power supply for electrostatic coating apparatus

Abstract: A power supply for generating a high unidirectional voltage at a charging electrode of an electrostatic spray coating apparatus has circuitry for sensing the magnitude of current flow to the electrode and for controlling application of an input voltage to the power supply in accordance therewith to control the magnitude of the high voltage. The arrangement is such that whenever the current flow is less than a predetermined value all cycles of the input voltage are applied to the power supply, but whenever the current exceeds the predetermined value only a limited number of the cycles are applied to the power supply. In this manner, the danger of arcing between the electrode and an article being coated is eliminated or at least significantly reduced.

High voltage high frequency analog signal measuring system

Abstract: Two phase-locked loop (PLL) solid state devices are used in conjunction with a fiber optics transmitter-receiver link in order to derive at a remote location an analog signal which is a representation of an inputted analog signal. Frequency-modulation is used in an analog signal measurement context to provide a bandwidth extending from direct current to a frequency of the order of 125 kHz. The transmitter portion is integrated within the base enclosure of a high voltage coupling capacitor connected between a high voltage power line and ground to provide high voltage protection and measurement capability for high frequency high voltage transients or surges in relation to high voltage power lines from the remote location.

High voltage direct current transmission

Abstract: Improved apparatus for discharging power from a high-voltage direct current line. A direct voltage convertor is connected in series with a smoothing filter and a DC high voltage line on one side and a second smoothing filter and a power discharge inverter on the other side. The rated voltage of the discharge inverter is substantially lower than the line voltage and the direct voltage convertor applies the lower voltage to the discharge inverter.

A doublesided cyclo-converter

Abstract: A power converter with reversible power flow which transforms a.c. or d.c. power of one form and voltage level to a.c. or d.c. power of another form and voltage level is presented. Use of a modulated high frequency link between two sets of matrices of switches at the output terminals allows the application of active filtering processes, the elimination of all low frequency filters and transformers; it allows furthermore, arbitrary and independent programming of the power factors at the two ports. Low weight and cost of apparatus is enhanced by the time proven reliability of its significant functional elements. The potential for the construction of megawatt capacity systems is derived from experience with the basic class of those converters and is reinforced by the report of reduction to practice of some of the described techniques in the form of a 3 kW model in a companion paper.

Phase modulated power control

Abstract: An apparatus for applying AC power to a load while maintaining a minimum charge across a capacitor for use as a DC power supply, that may be connected in series with the power supply and load, and does not require a parallel connection to the power supply, including power control means responsive to the phase of the power supply signal such that the voltage across said power control means is allowed to rise to a given voltage each cycle, before power is applied to the load, and charging means operable to charge said capacitor to said given voltage.

A Fast Stability Program For Power Systems With Multiterminal HVDC And Static Var Comensators

Abstract: This paper presents a digital computer program that employs a novel, fast and efficient technique to solve transient stability problems of large scale power systems. The program has the unique features of simulating generalized (two and multi-terminal) HVDC schemes; and different types of static reactive power compensators, as well as other conventional components in a power system. Results for a complex ac/dc multimachine system under low short circuit ratio conditions are presented.

Three phase undervoltage monitor

Abstract: A three phase undervoltage monitor separately converts the voltage on each phase to a D.C. voltage, compares each of the separate D.C. voltages with a reference voltage, and operates an output signal whenever one or more of the voltages drops below the reference voltage.

Single-phase reactive power converter

Abstract: PURPOSE: To enable detection of a reactive power with small errors even for an imbalance three-phase power system and a frequency fluctuation system by multiplying the volume of electricity corresponding to the current and voltage of a power system phased in a prescribed manner and by removing an unrequired component of frequency with a filter. CONSTITUTION: The current and voltage of a power system are converted into prescribed electric volumes by input converting circuits 1 and 2, while they are advanced or delayed in shifting respectively by phase angles of θ, 90-θ degrees by phasers 3 and 4. And when the outputs of the phase shifters 3 and 4 are processed for multiplication in a multiplying circuit 5, they turn to be a DC component proportional to the volume of the reactive power and a higher harmonic component which is double the volume of inputted electricity. When this unnecessary higher harmonic component is removed by LPF 6, the reactive power with small errors also for an imbalance three-phase power system and a system wherein the frequency fluctuates is detected and thus the single-phase reactive power converter which can continue operation even when the rated frequency is changed. COPYRIGHT: (C)1981,JPO&Japio

Novel capacitor-divider voltage sensors for high-voltage transmission systems

Abstract: For some time, it has been recognised that conventional capacitor voltage transformers (c.v.t.s) have transient response limitations which affect the performance of modern high-speed protection. To take advantage of existing and new types of distance protective systems, capable of performing accurately withing the first 20 ms of fault inception, a high-fidelity voltage measurement system which overcomes the limitation of conventional c.v.t.s has been developed. The novel high-fidelity voltage sensor comprises a conventional capacitor divider and solid-state amplifier system, the latter being suitable for application with existing designs of capacitor voltage transformer, purpose-designed capacitor voltage dividers, or with capacitor-probe facilities in SF6 metal-clad switchgear installations. A summary of the results of the various tests which have led to the development and design of a fully engineered system are described. Reasonable correlation is shown to exist between actual performance of the novel c.d.v.s on the 400 kV system and laboratory tests. Technical performance requirements for high-speed protection covered by the IEC Recommendations, Publications 186, 1969, and 186 A, 1970, and other special requirements are evaluated in a manner which could be used as a basis for design specifications. The paper concludes by considering economic aspects and future possibilities.

Summary of a Guide for Determining the Maximum Electric Power Station Ground Potential Rise and Induced Voltage from a Power Fault

Abstract: Difficulties are experienced by telecommunication and protective relay engineers in determining the maximum power station ground potential rise, and/or induced voltages. Suitably rated protective devices are required for personnel safety and for the protection and continuity of service of wire line telecommunication facilities entering electrical power stations, or otherwise exposed to the influence of electrical power circuits. This is a summary of the IEEE Standards Ccmmittee Project No. P 367 proposed Guide which provides guidance for the calculation of these maximum voltages and for the acceptance of values lower than maximum, as well as the time requirements of coumunication channels where protective relaying is involved. The proposed Guide was submitted to the IEEE Standards Board by G. Y. R. Allen, Chairman of the PSOC Wire Line Subcommittee of PES and Chairman of the Inductive Coordination and Electrical Protection Subcommittee (Transmission Systems Committee) of the Cc mnunications Society.

Power supply circuit of the high voltage type for electrical discharge machining apparatus

Abstract: An improved high voltage module for use in conjunction with a standard power module. The high voltage module includes a floating power supply in parallel with the standard power module and without ground connection included in the high voltage module are a plurality of stages of Darlington amplifiers. The two modules are opticoupled in the circuit with provision for fast turn-on and turn-off networks for the opticoupling network.

Improvement of power system stability using static voltage stabilizer

Abstract: The effects of the static voltage stabilizer on the stability of a bulk power transmission line were investigated. Two types of stabilizer are considered. One is a saturable-reactor type and the other is a thyristor-controlled reactor type. Control method and transient behavior are discussed in the case of a thyristor-controlled reactor type. By this analysis it can be determined whether the power system can be represented by fundamental components only, neglecting the harmonic components. The optimum value of controlled voltage to suppress the power swing is also derived. The effects of the static voltage stabilizer in comparison with those of series capacitor compensation are also examined. It was concluded that the voltage control via voltage stabilizer is effective to improve stability, especially in heavy load conditions.

Degraded or Loss of Voltage Protection of Class 1E Auxiliary Power Systems in a Nuclear Power Plant

Abstract: This paper analyzes the protection of onsite emergency power systems in nuclear power plants from sustained degraded or sudden loss of voltage conditions of the off-site power. This analysis develops insights into the problems of existing operating nuclear facilities and establishes corrective actions. The protection philosophy and design of protective scheme developed in this paper are adaptable to back-fitting operating nuclear facilities and also iterative approach to the design of relay protection system for new nuclear power plant that will be on-line in mid 1980's. The design approach emulates the recent Nuclear Regulatory Commission staff positions with regard to susceptibility of safety related electrical equipment during sustained degraded voltage conditions at the offsite power sources.