Abstract: A steady-state security region is a set of real and reactive power injections (load demands and power generations) for which the power flow equations and the security constraints imposed by equipment operating limits are satisfied. The problem of determining steady-state security regions is formulated as one of finding sufficient conditions for the existence of solutions to the power flow map within the security constraint set. Explicit limits on real and reactive power injections at each bus are obtained, such that if each injection lies within the corresponding limits, the system is guaranteed to operate with security constraints satisfied.

Abstract: Perusal of the V-I characteristics of commercial solar panels with insolation, ambient temperature and production spreads as parameter, indicate that the maximum power is obtained from such a panel when it is loaded to a working voltage that is a fixed percentage of its open circuit voltage within (+2)%. This contribution describes a system that uses this characteristic to achieve maximum power control by determining the open circuit voltage and automatically loading the panel to the maximum power point as applied to a battery charging installation. The description includes the application of a novel modified darlington circuit to boost the efficiency of a pulse width controlled switch mode type regulator by reducing the darlington saturation voltage by a compensating voltage. Advanced switching technology is applied to reduce switching losses, and maximise efficiency.

Abstract: One method of obtaining energy conservation and peak load reduction is through a reduction in voltage on the utility distribution circuit This paper describes a voltage reduction program which included circuit testing to determine voltage reduction effects, data analysis to isolate the sensitivity of loads to voltage, and circuit analysis to determine categories of loads The actual tactics used to effect the desired reduction in voltage and consumption are also described

Abstract: An apparatus and method for stabilizing an output of a DC power source by using a micro-computer to regulate an input voltage to provide an output voltage according to a controlling signal The invention further utilizes a periodic interruption process in the program sequence which moniters the output voltage, compares it to a predetermined level and regulates the output voltage in accordance with the monitered voltage

Abstract: A low voltage protection which prevents an associated circuit from generating erroneous signals during power-up, power-down or power failure conditions. A voltage comparison circuit, powered by a first power supply, detects low voltage conditions in a second power supply and causes a switching circuit to inhibit control and power signals of the associated circuit.

Abstract: A method of static reactive power compensation is disclosed wherein the system voltage is compensated by supplying advanced-phase or retarded phase reactive power in dependence upon the difference between the system voltage and a reference voltage. The difference is formed by a comparator which receives a variable reference voltage from a filter containing a time lag circuit and which receives the system voltage as an input. For transients, the output of the filter does not change and thus reactive power is applied. For smooth variations, the output of the filter follows that of the system voltage so that the output of the power compensation circuit is maintained at zero.

Abstract: Apparatus for detecting, in advance, by a desired length of time, the imminent failure of electric output power provided by an electric power supply due to the reduction or loss of input power. The magnitude of the voltage on an energy storage reservoir capacitor is monitored for deriving a voltage signal proportional to the rate of change thereof. The rate of change voltage is multiplied by a voltage proportional to a desired early warning time interval and this product is added to a voltage proportional to a minimum value of voltage on the capacitor, thus representing an amount of stored energy sufficient to sustain normal output power for a desired time interval. The voltage derived by the adding means is compared with the voltage on the energy storage capacitor for signalling imminent power supply failure when the compared voltages are equal.

Abstract: A variable speed drive for an AC motor has features to improve the power factor. The system uses a rectifier for converting AC supply voltage into DC voltage on a positive rail and a negative rail. Frequency switches are controlled to alternately connect the rails to the power conductors at a variable rate to define a selected voltage frequency. An amplitude switch is located on one of the rails and controlled to vary the potential between the rails in proportion to the frequency. A current sensor senses the current waveform in one of the conductors and applies it to a phase detector which detects the difference in phase between the current and the voltage. Phase difference pulses are produced which are averaged into an average DC value. The DC value is applied to a demand voltage that controls the amplitude switch to reduce the amplitude to improve power factor.

Abstract: A high-frequency, high power n-channel MOS-FET suitable for use in aural power amplifiers of the VHF television transmitters was designed and fabricated. The maximum drain-source voltage as high as 130 volts was obtained with an ON resistance of 0.3 ohm at a gate-source voltage of 20 V with a drain current of 3 A. The drain-source feedback capacitance was designed to be 0.8 pF to operate the MOS-FET at VHF frequencies. The MOS-FET was satisfactorily operated at 250 MHz and the power gain was of 7 dB.

Abstract: An automatic voltage control system controls the voltage delivered to the primary winding (12) of a step-up transformer (10) and hence the power delivered to a dehydrator (40) so as to prevent the step-up transformer (10) from exceeding rated power when a current limit occurs. The automatic voltage control system controls the voltage applied to the primary winding (12) so as to maximize the voltage applied to the grid elements (38) of the dehydrator (40). Upon encountering a current limiting condition, the automatic voltage control system reduces to zero the voltage applied to the primary winding (12) and hence the power applied to grid elements (38) of the dehydrator (40) to dissipate the cause of the current limiting condition. The voltage is reapplied to primary winding 12 at a voltage level below where the current limit occurred. The voltage is then increased to maximize the voltage applied to the grid elements (38) of the dehydrator (40). Upon encountering a voltage limit, the voltage is maintained at a constant level until either an arc or current limit are encountered whereupon the control cycle is repeated.

Abstract: PURPOSE:To ensure the following even to the frequent actions carried out to the variation of the system conditions and the load by selecting a controller after deciding whether are deviation between the system voltage and the reactive voltage which is generated by the variation of the back voltage at the system side. CONSTITUTION:Both the system voltage and the reactive power of systems 1-3 are measured by a CPU76 via input signal converters 71-75 of a voltage-reactive power controller 7. The CPU76 identifies the initial value from said measured value as well as the system reactance from the initial value and its variation. Then the CPU76 decides whether the deviation between the system voltage and the reactive power which is due to the variation of the system back voltage satisfies a specific function relation decided by the prescribed system voltage, the blind sector width of the reactive power and reactance respectively. Based on this decision, the CPU76 selects a tap switch 41 or a breaker 51 for shunt reactor and a breaker 61 for static capacitor via output signal converters 77-79. These controllers are sequentially operated.

Abstract: When designing a power plant dc system, the engineer must be cognizant of the limitations that the selected nominal voltage level places on the system. A discussion (from design, operation, and economic viewpoints) of the advantages and disadvantages of commonly used dc voltage levels is presented. Recommendations on system voltage selection are made.

Abstract: An analytical model is developed to allow effective reactive power control in critically loaded power transmission systems. Representation of the transmission network, tap-changing transformers, and nonlinear loads is incorporated. The model has application in computer control and monitoring of transmission voltage performance.

Abstract: In a method and a test circuit for testing isolated cable sections for earth fault, particularly medium- or high-voltage cables which can be open at their end or can be connected by loads, it should also be possible reliably to detect high-impedance and voltage-dependent insulation faults and reliably to prevent the power system voltage from being connected when insulation faults have been found. For this purpose, the cable is continuously charged up by a charging current (IL) to a voltage (UL) the amplitude of which corresponds to that of the power system voltage before the power system voltage is connected. At the same time, a current (IV) proportional to the charging current (IL) charges up a comparison circuit (10), the voltage (UV) of which is continuously compared with a voltage (UM) corresponding to the charging voltage (UL) of the cable. When a nominal measurement voltage (UN) proportional to the nominal power system voltage is reached (UM >/= UN) by the voltage (UM), the test process is ended and the connection of the power system voltage is enabled whilst, when the voltage (UM) drops below (UM

Abstract: PURPOSE:To attain a rapid CPU operation through a single electric power supply, by driving an ROM, an RAM, an instruction decoder and a CPU in an one- chip microcomputer by the voltage boosted from the primary voltage. CONSTITUTION:The voltage of a low voltage single power supply 1 is boosted by a boosting circuit 4 consisting of boosting capacitors 2, 3, etc. and the boosted voltage is supplied to a central processing circuit CPU5, an oscillation circuit 6, an ROM7, an RAM8, and an instruction decoder. Since the boosting circuit 4 supplies double voltage power to a boosting power supply system driving part 9, the rapid operation of the CPU5 is attained. In addition, power consumption is reduced by operating the oscillation circuit 5 at low voltage.

Abstract: Standard means of measuring high dc voltage are usually based on precision resistive dividers. Special parametric testing methods have been developed in the USSR and abroad for checking these, in which the effect of corona and leakage currents along the surface of the divider component is taken into account [1-3]. However, these methods are not completely correct. The reliability with which the scale division factor is determined when a high operating voltage is present can be increased considerably if the elements of the divider have low resistances. This would enable one to neglect the resistance to corona currents to ground and the resistance of the leakage current through the insulation. However, such a divider would consume considerable power from the measuring circuit, its elements would heat up, and as a consequence a considerable temperature error would be introduced. Consequently, for precision measurements in high-voltage circuits is is best to use apparatus having a comparatively high input impedance, i.e., which do not take too great a current from the measuring circuit, and have a low internal (output) resistance.