Abstract: In a power supply apparatus for discharge surface treatment which uses a green compact electrode as a discharge electrode, allows a pulse-type discharge to take place between said discharge electrode and a workpiece, and forms a film, which is made of an electrode material or a material obtained when the electrode material reacts to a discharge energy, on a surface of the workpiece following three measures are taken. (1) When a discharge voltage detected by the voltage detection means is less than or equal to discharge detection voltage set value which is slightly lower than a power supply voltage, the electric current cut-off means forcibly cuts off an output of the oscillator so that long-time pulse is prevented. (2) A capacitor is connected in parallel with an oscillation circuit of the oscillator, and the long-time pulse is prevented by capacitor discharge. (3) Time that the discharge takes place once is controlled by a timer so that the long-time pulse is prevented.

Abstract: Variable shunt and series connected reactors are used in a complimentary combination in an electric arc furnace to provide improved flicker control. A power control system for an time-varying AC load, such as an electric arc furnace, connected to an AC power supply line includes a first variable reactance intermediate the power supply line and the load, and a second variable reactance connected in parallel with the power supply line. A control system is provided for (i) monitoring load current and adjusting the first variable reactance in response to changes in the monitored load current; and (ii) monitoring reactive power draw by the load and adjusting the second variable reactance in response to changes in the monitored reactive power draw. The first variable reactance and second variable reactance are each primarily used to mitigate flicker at different times during the load operation.

Abstract: The system includes an enable signal applied to an output AND element. A comparator compares the voltage ratio of selected measured and calculated phase-to-phase or single phase voltages against a threshold value. An AND gate is responsive to a high signal from the comparator and indications of a three pole open condition, a single pole open condition for selected poles, and a loss of potential condition. A high output from the AND gate is applied to a timer, which produces a high output for a short period of time, which controls the output element. The output element provides a blocking signal for the protective elements under particular conditions and a permissive signal under other conditions.

Abstract: Variable shunt and series connected reactors are used in a complimentary combination in an electric arc furnace to provide improved flicker control. A power control system for an time-varying AC load, such as an electric arc furnace, connected to an AC power supply line includes a first variable reactance intermediate the power supply line and the load, and a second variable reactance connected in parallel with the power supply line. A control system is provided for (i) monitoring load current and adjusting the first variable reactance in response to changes in the monitored load current; and (ii) monitoring reactive power draw by the load and adjusting the second variable reactance in response to changes in the monitored reactive power draw. The first variable reactance and second variable reactance are each primarily used to mitigate flicker at different times during the load operation.

Abstract: An active digital voltage regulator circuit is a two terminal device that is connected in shunt to first and second power supply input lines. The active digital voltage regulator circuit stores energy during times when the local power supply voltage is greater than a predefined voltage, e.g., during times when the parasitic inductances supplement the local power supply voltage. The active digital voltage regulator circuit uses the stored energy to supplement the local power supply voltage during times when the local power supply voltage starts to collapse, e.g., during periods when inductive losses are preventing the power supply from maintaining the local power supply voltage. Consequently, digital active voltage regulator circuit smooths the local power supply voltage by greatly ameliorating the ripple voltages associated with parasitic inductances and resistances. A control circuit within the regulator circuit is a combination of two self-biasing and off-set nulling power supply monitor circuits.

Abstract: Disclosed are a power control apparatus and method thereof capable of controlling a load power by adjusting an AC power voltage supplied to a streetlamp, a computer system, and electronic equipment according to a load characteristic and object. The power control apparatus comprising: a current coil for varying a voltage; a current detecting section for detecting a current and outputting a data, an input voltage detecting section for detecting a voltage; an output voltage detecting section for detecting the voltage; a system controller for outputting a plurality of trigger control signals controlling a peripheral equipment and identifying an operation condition of a system; a switching section operated according to the plurality of trigger control signals; and an output voltage adjusting section for determining increase or decrease of the flux linkage of the current coil.

Abstract: A series-compensating power flow transformer implements power flow control in a transmission line of an n-phase power transmission system, where each phase of the power transmission system has a transmission voltage. The transformer has n primary windings, where each primary winding is on a core and receives the transmission voltage of a respective one of the phases of the power transmission system. The transformer also has n secondary windings on the core of each primary winding for a total of n2 secondary windings. Each secondary winding has a voltage induced thereon by the corresponding primary winding, and one secondary winding from each core is assigned to each phase. For each phase, the secondary windings assigned to the phase are coupled in series for summing the induced voltages formed thereon, where the summed voltage is a compensating voltage for the phase.

Abstract: A high-efficiency tracking power supply feating a network of switched capacitors and an active noise shaping unit for reducing non-linearity and controlling the noise spectrum. Several variations of an non-inductive switched-capacitor tracking power-supply are presented whch are well-suited to integrated-circuit implementation and battery operation, and which provide ani efficient power supply for the output stage over a wide range of volages that can exceed the votage limits of the main power source, The output of tile tracking power-supply can be fed into an analog linear voltage regulator, or can be used as a Multi-Level Quantizer for generating the output directly. Some simple switching strategies are disclosed which offer power efficiencies in excess of 90%.

Abstract: A power flow transformer implements power flow control in a transmission line of an n-phase power transmission system, where each phase of the power transmission system has a transmission voltage. The transformer has n secondary windings, where each secondary winding is on a core. The transformer also has n primary windings on the core of each secondary winding for a total of n2 primary windings, where one primary winding from each core is assigned to each phase. For each phase, the primary windings assigned to the phase are coupled in series, and the in-series primary windings receive the transmission voltage of the respective phase of the power transmission system. For each core, each primary winding thereon induces a voltage in the secondary thereon. The induced voltages are summed by the secondary to result in a summed induced voltage. Such summed induced voltage is a compensating voltage for a respective phase.

Abstract: A synchronous switching apparatus for detecting a source voltage of each phase to close each phase at an electrical phase angle predetermined for each phase, including switching devices 1a-1c provided one for each phase for opening and closing an impedance load, switching devices 2a-2c for closing and opening the switching devices 1a-1c for each phase, measuring transformers 5a-5c for measuring source voltages of the respective phases and phase-to-phase voltages, and phase control devices 42 each for issuing a command for energizing the impedance load at an electrical phase angle in a range predetermined for each phase, when detecting a zero point of a source voltage of each phase or a zero point of each phase-to-phase voltage.

Abstract: A voltage amplitude adjuster including semiconductor switches for power conversion, an AC chopper for converting an input AC voltage to an AC voltage of the same phase and different amplitude relative to the input AC voltage, and a smoothing AC filter for providing a clear signal to a primary winding of a transformer. Further, by providing a wattmeter, the saved power can be displayed.

Abstract: Switched power converter with hold-up time and harmonics reduction connected to an AC power mains through a first rectifier means (13) and connected to conversion means (19) supplying a regulated voltage. An energy storage means (16) connected in parallel with the rectifier means (13), absorbs or supplies current to the conversion means (19), by adapting the conducting periods of two switching devices in such a way that determines the voltage level on the storage means (16) and assures a sinusoidal current at input terminals (11, 12). The two switching devices are switched in a complementary manner by means of a first control means included in the energy storage means (16).

Abstract: A voltage sag generator for alternating current power systems intentionally creates power quality disturbances. The sag generator has a switch-mode impedance between its input and its output. Varying the duty-cycle of the switch-mode impedance causes voltage sags.

Abstract: A circuit and method for regulating power supplied on a network which provides power to an electric arc furnace or other highly variable load. The circuit includes at least a first inverter connected in series with the arc furnace transformer, and in shunt with the power supply. The circuit and method provide an effective, low cost technique for controlling network power.

Abstract: A method and system for preventing sustained resonance conditions in a power system involves measuring voltage and current samples on a conductor to which a plurality of controlled capacitors are operatively coupled. The measured voltage and/or current is utilized to identify a resonance condition. The method or system determines whether the resonance condition is due to switching of a controlled capacitor and, if so a corrective switching operation is performed after a first time delay. If the resonance condition is determined not to be due to the switching of a capacitor, then a second switching operation, in which a second controlled capacitor is switched after a second time delay, is performed. The second time delay is preferably greater than the first time delay.

Abstract: A polyphase thyristor-switched-capacitor static var compensator (SVC) arrangement employs a transformer circuit connected to the capacitors of the SVC and configured such that when the capacitors are switched out of circuit in sequence, a residual charge on the capacitors is reduced by the transfer of energy between the capacitor and an energy-dissipation circuit by way of the transformer circuit. The primaries of the transformer circuit are connected across respective capacitors, while the secondaries are connected in series in a delta configuration. Damping resistors may be connected in series with the primaries to help dissipate the capacitor energy. The transformer circuit may be saturable and may be constituted by individual transformers or one polyphase transformer.

Abstract: An active digital voltage regulator circuit is a two terminal device that is connected in shunt to first and second power supply input lines. The active digital voltage regulator circuit stores energy during times when the local power supply voltage is greater than a predefined voltage, e.g., during times when the parasitic inductances supplement the local power supply voltage. The active digital voltage regulator circuit uses the stored energy to supplement the local power supply voltage during times when the local power supply voltage starts to collapse, e.g., during periods when inductive losses are preventing the power supply from maintaining the local power supply voltage. Consequently, digital active voltage regulator circuit smooths the local power supply voltage by greatly ameliorating the ripple voltages associated with parasitic inductances and resistances. A control circuit within the regulator circuit is a combination of two self-biasing and off-set nulling power supply monitor circuits.

Abstract: In an interconnection system (100) for transferring power between a first grid (22) operating at a first electrical frequency and voltage and a second grid (24) operating at a second electrical frequency and voltage, compensation circuits including a shunt compensation circuit (40) and a series compensation circuit (50) are provided for use in conjunction with a rotary transformer (102). The shunt compensation circuit (40) regulates voltage by adjusting reactive current injected in shunt, and is preferably connected between the first grid (22) and the rotary transformer (102). The series compensation circuit (50), which regulates e.g., reactive power flow through the rotary transformer (102), is preferably connected to a transformer (30) which interfaces the first grid (22) to the rotary transformer (102).

Abstract: DVRs and APLCs utilize a single transformer for injection of compensating voltages into an ac power line and for drawing power from or exchanging power with the ac power line. The poles of an inverter are connected in series with the wye connected transformer primary winding which is also connected to the source end of the power line. A first secondary winding is connected to the load end of the power line. A rectifier circuit or a power interface inverter in the DVR and APLC, respectively, is connected to a second secondary winding on the transformer. For high pulse numbers, the rectifier circuit or interface inverter can have additional rectifier bridges or inverter poles connected to additional transformer secondary windings phase shifted with respect to each other. The single transformer can be a load transformer already provided in the power line, thereby further reducing the cost of the arrangement.

Abstract: A power lag compensation device is provided including a housing. A socket assembly is situated within the interior space of the housing for releasably receiving a plug connected to an appliance for being in electrical communication therewith. A plug assembly is mounted on the housing and extended therefrom exterior of the housing. The plug assembly includes a pair of spaced parallel rectangular prongs. The rectangular prongs each have an associated interconnect wire connected to a corresponding socket of the socket assembly. The plug assembly serves to releasably insert within a socket which is connected to an alternating current power source. A triggering mechanism is connected in communication with one of the interconnect wires within the housing. The triggering mechanism is adapted for producing an activation signal upon the detection of a current flow therethrough.

Abstract: A trigger control system for a thyristor-controlled series capacitor (TCSC) is disclosed. In one application, a power system 10 is coupled to a load 12 by a series capacitor 14 connected in parallel to a thyristor unit 16 and inductor 17. The thyristors are triggered by the control system 18, which includes a first circuit 20 that generates signals proportional to the peak of the line currents, a stabilizer circuit 22, an adder 24, a look-up table 26, a conversion circuit 28, a pulse generator 30, a phase-locked loop (PLL) 32, a ramp generator 34, a trigger window circuit 36, and a three input AND gate 38 the output of which is a grid pulse signal 40 that triggers the thyristor unit 16. The control system diminishes power swing oscillations and subsynchronous resonance oscillations.

Abstract: An electrical power transmitting system (50) in accordance with the invention includes an alternating current electrical power generator (12) for producing alternating current on an output having a specified maximum; at least one electrical load (22) which is coupled to a point of regulation (16) in the electrical transmitting system; a feeder (14) having a specified maximum voltage drop, a length extending between the output and the point of regulation for transmitting the alternating current to the point of regulation, an inductance having an inductive reactance at a fundamental frequency of the alternating current, a capacitance (54, 66, 80 and 100) in series with the inductance having a capacitive reactance at the fundamental of the frequency of the alternating current which cancels at least part of the inductive reactance at the fundamental frequency of the alternating current to provide a reduced impedance in the feeder at the fundamental frequency of the alternating current to produce a reduced voltage

Abstract: An apparatus for retrofitting an HID light fixture is described in several embodiments. The apparatus is coupled in series with the secondary winding and the HID lamp of the HID light fixture. A first retrofit capacitor replaces the light fixture capacitor of the HID light fixture. A switching device is coupled in series with a second retrofit capacitor and couples the first and second retrofit capacitors in parallel in response to a normal power mode control input so that the HID lamp provides normal intensity lighting at normal power. The switching device uncouples the first and second retrofit capacitors from being in parallel in response to a low power mode control input so that the HID lamp provides low intensity lighting at low power.

Abstract: A device for suppressing higher harmonic current of a power source and applicable to a switching power source, air conditioner with an inverter, lamp regulator or the like. The device suppresses higher harmonic current by increasing the conduction angle of input current.

Abstract: An active damping control device for an active power filter includes a filter circuit having an inductor and a capacitor for suppressing noise in the active power filter; a first current sensor for sensing a three phase capacitor current of the filter capacitor; a second current sensor for detecting a three phase load current; and an active power filter controller for extracting the fundamentals of the capacitor and load currents and calculating a reference current for the active power filter.

Abstract: A switch-off method for a three-phase solid state reactive power compensator for a rotary three phase power system has first and second thyristor valves receiving respective first and second firing signals, and three capacitors. The firing signals are suppressed to a point in time for first turning off the second firing thyristor valve in immediately successive phases in direction of rotation of the three-phase power system.

Abstract: A static reactive power compensating equipment includes a circuit for preventing harmonic currents generated by adjusting lag compensation current from phase control from flowing out of the equipment. A first reactor and a controller are connected to a switching circuit. A second reactor is connected between an output terminal and a connection node. The first reactor is also connected to the connection node such that the first and second reactors are series connected. A resonant circuit including a third reactor connected in series with a capacitor is connected to the connection node such that the resonant circuit is series connected with the second reactor and parallel connected to the first reactor. The resonant circuit is constructed to resonate at a predetermined frequency which substantially absorbs harmonic currents flowing from the static reactive power compensating equipment.

Abstract: Using a switching circuit (2) for a reactive power compensation device (1), he compensation capacitors of the reactive power compensation device (1) can be switched on with voltage measuring devices (30, 31) which are switched between two phase conductors (3, 4) if the the voltage is the same on both sides of an open phase conductor switch (24). In a preferred embodiment, closing the second phase conductor switch (25) occurs triggered by a delay device (36) following a fixed delay time. In another preferred embodiment, switching on occurs when the voltage is the same between the phase conductors (4,5) on both sides of the second phase conductor switch (25), whereas this condition can be checked with two other voltage measuring devices switched between the phase conductors (4, 5) as well as with another equivalence comparator.

Abstract: A voltage regulator regulates the voltage a static VAR compensator (SVC) supplies to a power supply network. An SVC status detector detects the conducting status of the SVC thyristors and generates the measured SVC susceptance in accordance with that conduction status. A calculator calculates a representative voltage, (i.e. the Thevenin equivalent), of the power supply network based on the measured SVC susceptance, measured SVC voltage, and an estimate of the power supply network's equivalent reactance. An ordered susceptance to be provided by the SVC to maintain the SVC voltage at a desired level is predicted based on the calculated voltage. A firing control unit receives the predicted susceptance value and calculates drive signals for controlling thyristors in the SVC. The equivalent reactance is initially estimated, and thereafter, it is modified automatically to track and compensate for large disturbances in the power transmission network.

Abstract: The present invention provides method and apparatus for reassigning switched capacitors which are lost as a result of circuit reconfiguration. A power distribution network includes a plurality of substations. Each substation includes a master controller which manages switching operations of a plurality of load regulation capacitors. The capacitors which are a part of the same circuit as a given master controller are normally under the control of that master controller. Each time a load regulation capacitor is connected or disconnected, a change in the voltage level and the VARs level is observed on the distribution line to which the capacitor was connected.

Abstract: A method and apparatus is described for generating a synchronizing signal for a firing-circuit subassembly to trigger a power converter valve of a controlled series compensator. According to the invention, a sinusoidal substitute variable is provided, which can be either a measured line current or the sum of a capacitor current and a valve current, such that the zero crossings of said substitute variable do not vary. This substitute variable is modified in terms of its phase position so that a synchronizing signal that corresponds to the phase position of the capacitor voltage of the series capacitor of the controlled series compensator is made available to the firing-circuit subassembly. The result, even in the bypassed state, is a sinusoidal synchronizing signal whose zero crossings do not vary, so that operating stability problems no longer occur in the transient state during operation close to resonance.

Abstract: An embodiment of the present invention is a boost preregulator circuit which includes a bridge rectifier, an inductor, a boost diode and an output capacitor. A power transistor is switched on and off across a junction of the boost inductor and boost rectifier according to a variable duty cycle. Proper variation of the duty cycle results in a power factor corrected AC line current waveform with an in-phase sinusoidal shape.

Abstract: A device runs a precheck of an inductive load for an overload prior to swhing on to supply mains. For this purpose, following switching-on for a load precheck, initially a phase limited voltage signal is applied to the load, whereby the voltage signal duration gradually increases. With the start of each application of voltage, the active current is measured in a narrow time window. If it does not exceed a predetermined active current limit at an application of a specific effective voltage, the load is switched to the mains. Otherwise, the switch-on process is cut off. This switching-on process avoids a high taxing of the mains in the event of a short circuit or an overload. The active current window begins with the application of voltage to the load. At a different time than this time window, a further measurement window is provided for the reactive current, whereby this measurement window begins with the zero crossing of the alternating voltage.

Abstract: A firing controlled scheme including a method and apparatus for vernier operation of a shunt-connected thyristor-controlled capacitor (STCC) uses phase controlled firing of the thyristors based on monitored line voltage, monitored thyristor current, and a thyristor current command to vary the effective reactance of the capacitor. The STCC includes a capacitor and surge inductor connected in shunt across a power transmission line via a thyristor switch. A vernier controller predicts an upcoming firing angle based on the above parameters and switches the thyristor circuit to partially conduct pulses of thyristor current at different amplitude levels depending upon the commanded firing angle. By varying the firing angle, variable inductive and capacitive reactive power can be selectively delivered to the transmission line.

Abstract: Controlling a customer voltage and VAR flow in a power transmission and distribution system includes measuring first voltages in a power line directed to a first location related to customers. Both the customer voltage and the VAR flow for the network is determined in relation to the number of capacitors associated with the first location which are switched in or out of the network. The measured voltages are communicated to a voltage control. Voltage deviations of the measured first voltage are determined relative to a predetermined voltage range intended to be present at the first locations. Switching the capacitor means into or out of the network is determined by the voltage control in accordance with a voltage rise table. A VAR flow controller is responsive to the voltage at the first locations, the effect of the VAR generation by the capacitors and the change of VAR generation by the capacitor. A decrease in voltage at the customers saves energy use.

Abstract: An impedance compensator for adjusting the power factor of a power distribution system by directly measuring impedance at a point in the power distribution system and dynamically adjusting that impedance to be resistive yielding a power factor of one. The compensator dynamically inserts and removes both capacitance and inductance to adjust the impedance. The inductance is utilized to make coarse adjustments to the impedance, whereas the capacitance is utilized to make fine adjustments.

Abstract: A method and a device for recognizing defects in a triggering system of a controlled series compensator. An intervention is made in the closed-loop control of the controlled series compensator on the basis of an impedance differential (.DELTA.Z) determined from a setpoint impedance (Z.sub.S1, Z.sub.S2) and from an effective impedance (Z.sub.i) calculated from system variables (i.sub.L,u.sub.C), and in dependence upon the voltage level of a measured conduction current (i.sub.L). When the conduction currents (i.sub.L) are smaller than a limiting value (i.sub.LG), the firing is blocked in the branches, and when the conduction currents (i.sub.L) are greater than a limiting value (i.sub.LG), a firing-angle signal (S.sub..alpha.S) is generated, through which means the valve (Th1, Th2) can be protectively fired. Thus, one is able to recognize defects in the triggering system of the controlled series compensator by applying system variables (i.sub.L,u.sub.

Abstract: A compensating circuit arrangement for a power transmission system for rapidly inserting capacitance into a transmission line for desired portions of cycles of the operating frequency of the system, has first anti-parallel connected thyristors in series with a capacitance and second anti-parallel connected thyristors in parallel with the series connected first thyristors and the capacitance. A control responsive to a variable in the system, and related to system reactance, switches desired thyristors on at desired times during a cycle of operating frequency to introduce controlled amounts of capacitance into the power transmission system.

Abstract: A capacitor bank installation for generating reactive power in high or extra high voltage electrical power systems, for example 345kV, to maintain the voltage level during heavy loading conditions or system contingencies. A three phase capacitor bank is connected between the high voltage line and the low voltage line by a first switching device which is connected between the high voltage line and the capacitor bank and by a second switching device which is connected between the capacitor bank and the low voltage line. The first switching device is a current interrupting device in series with a motorized disconnect switch which has a lower recovery voltage withstand capability than would be required if switching a shunt capacitor bank connected to the high voltage system. The second switching device is a motorized disconnect switch without any current interrupting capability.

Abstract: A method and an apparatus for symmetrically modulating a controlled series compensation system (2) in electrical networks (6). Impedance manipulated variables determined from a current control for the series compensators (14) of the system (2) are limited by determining an upper or lower limiting value (Z.sub.OO,Z.sub.OU). The upper and lower limiting values are respectively determined by adding a positive or negative deviation (.DELTA.Z.sub.+,.DELTA.Z.sub.-) to and subtracting it from a reference manipulated variable (Z.sub.O) for impedance. The reference manipulated variable (Z.sub.O) for impedance is selected from the impedance manipulated variables (Z.sub.y1,Z.sub.y2,Z.sub.y3). Thus, small asymmetries can be corrected and, given network faults of generally only a brief duration, unnecessary control deviations can be avoided.

Abstract: An optically triggered solid state switch and method for switching a high voltage electrical current. A plurality of solid state switches (350) are connected in series for controlling electrical current flow between a compensation capacitor (112) and ground in a reactive power compensator (50, 50') that monitors the voltage and current flowing through each of three distribution lines (52a, 52b and 52c), which are supplying three-phase power to one or more inductive loads. An optical transmitter (100) controlled by the reactive power compensation system produces light pulses that are conveyed over optical fibers (102) to a switch driver (110') that includes a plurality of series connected optical triger circuits (288). Each of the optical trigger circuits controls a pair of the solid state switches and includes a plurality of series connected resistors (294, 326, 330, and 334) that equalize or balance the potential across the plurality of trigger circuits.

Abstract: A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line.

Abstract: Apparatus for controlling the reactive impedance of a transmission line where capacitive reactance is inserted in series in the line to compensate inductive reactance includes a plurality of three or more capacitor modules connected to each other in series to form a series combination of capacitor modules. Each module is individually bypassed by fast acting thyristor bypass switches so that a central automatic control system can selectively place all of the modules in series where a maximum compensation level is achieved (meaning that the total reactive impedance is at a minimum level), or to provide a minimum change with just one capacitor module.

Abstract: An exposure device with a metal-halide lamp for the exposure of photosensitive materials in reprographics includes a circuit having a power source and an adjusting device in the circuit for adjusting the lamp between exposure operations at full power and a power level reduced for stand-by operation. The reduced power level is preselected as a function of predetermined properties of the photosensitive materials.

Abstract: The reactance of series capacitor equipment connected to an electrical transmission power line can be changed during operation with the aid of a transformer on-load tap-changer which switches in or out a variable number of capacitor modules. The tap-changer comprises a tap selector, the contacts of which in currentless state can be moved between the capacitor steps, and a diverter switch with a plurality of sequentially operating contact members and with resistors arranged to prevent direct short-circuiting of the capacitor steps. The tap-changer can be at line potential and operated remotely by contact-moving means at ground potential.

Abstract: Simultaneous power and voltage control by a d-c-tie between a-c networks is carried out by means of fixed and switchable inductive and capacitive compensation elements including the tap changer of both converter transformers of a d-c-tie for setting the optimum operating point by a transformation ratio of the converter transformer taps matching the primary current ratio, of the converter transformer taps for the maximally permissible stage of the one converter transformer, taking into consideration control, extinction and overlap angles of the d-c-tie.

Abstract: A method and capacitor control apparatus for controlling the power factor and voltage on an electrical distribution line based on the power factor on the line subject to a voltage override control. Hysteresis above an undervoltage limit and below an overvoltage limit prevent undesired oscillation in switching the capacitor controls to and from the distribution line.

Abstract: Device for and method of modulating an electric current pulse in which an inductor is shunted by a closing switch element in order to define a loop. The loop is then opened, which magnetically transfers energy stored in the inductor to the other inductor elements. Included in the loop is a constant voltage opening switch element which limits the potential difference across an opening switch in the loop. Proper selection of the number of such loops included in the device, the inductance of the inductor elements, and the voltage for the constant voltage opening switch elements permits tailoring of the resultant current pulse to any load in any predetermined shape, including a square pulse in which current is maintained constant for the duration of the pulse.

Abstract: A power converter apparatus for a DC power transmission system or a frequency conversion system includes a control apparatus that functions such that during the operation of converters, when the output voltage of a constant reactive control circuit reaches the output voltage of a margin angle limited control circuit, a shunt reactor is interrupted or a shunt capacitor is closed, and when the output voltage of the constant reactive power control circuit reaches a control delay angle corresponding to the curve which has a difference .DELTA.Q compared with the curve P-Q at a minimum margin angle .gamma. min, the shunt reactor is closed or the shunt capacitor is interrupted.

Abstract: A static var compensator connected to a line node in a power transmission system and having a capacitor and a first reactor for producing and absorbing reactive power, respectively, and a second reactor connected between the line node and the common node of the first reactor and the capacitor for providing, in combination with the capacitor and the first reactor, a maximum leading reactive capacity so as to effectively reduce the capacities of the elements and for compensating for changes in reactive power resulting from a current fluctuation in response to a load fluctuation. The second reactor increases the reactive power produced by the capacitor when the reactive power absorbed by the first reactor is low and decreases the reactive power produced by the capacitor when the reactive power absorbed by the first reactor is high.