Abstract: A precision digital to analog conversion circuit and method are provided. A regulated direct current (DC) voltage having a DC voltage magnitude is supplied to a device, such as a processor. The processor generates a pulse width modulation (PWM) output signal based, at least in part, on the regulated DC voltage. An analog output signal is generated from the PWM output signal. The regulated DC voltage is compared to a precision reference DC voltage, the DC voltage magnitude is selectively adjusted based on the comparison.

Abstract: A reactance (capacitive and/or inductive) module that may be connected to an electrical power system of a real estate property such as a residential or commercial property. If the electrical power system has a net reactance power that is degrading a power factor of the electrical power system, the reactance module may compensate at least in part for this net reactance power by turning on and off various reactance banks. For instance, net inductance can be compensated for by turning capacitive banks on and off An external monitoring entity may receive remote communications from the reactive bank, allowing the external entity to track energy savings, energy credits, and perhaps even control the reactance module to improve power factor.

Abstract: In a control system for a static var compensator that performs phase control of a current of a reactor for each phase by a thyristor and thus controls reactive power, a detecting unit that detects a tertiary harmonic current flowing through each phase of the static var compensator is provided, and on the basis of the tertiary harmonic current flowing through each phase detected by the detecting unit, the thyristor of each phase is controlled so that the quantity of generated tertiary harmonic current of each phase becomes equal, and therefore an outflow of the tertiary harmonic current toward a system can be restrained by an inexpensive method.

Abstract: A device, a system, and a method for preventing power-producing wind turbine generators from tripping due to the detection of a low-voltage condition on a power grid are disclosed. The disclosed device includes a resistor bank that absorbs real power and a control system that maintains the collector bus voltage above a threshold voltage level during the duration of low-voltage condition on the power grid. Collector bus voltage is maintained using gating signals that include phase delay angles to adjust the opening/closing of the switching devices.

Abstract: An electrical energy transmission device has phase conductors, which carry alternating current and have transfer impedance, and sheathed conductors, which are inductively coupled to the phase conductors. A first end and a second end of each sheathed conductor form a sheath circuit with a reactance. An electronic assembly for changing the impedance of the sheath circuit is provided. The electrical energy transmission device can be used flexibly given different demands placed on the energy transmission. The electronic assembly is also configured to increase the transfer impedance.

Abstract: An apparatus for controlling a power flow in a high voltage network. A phase shifting transformer includes a tap changer.

Abstract: Disclosed is an actuating circuit and method for actuating a switch regulating the power consumption in a power factor correction circuit having input terminals for applying an input voltage and output terminals for providing an output voltage. The switch is cyclically turned on for an on-time and turned off for an off-time, the on-time having a first on-time period and a second on-time period directly adjacent to the first on-time period. A length for the first on-time period is dependent on the control signal, and a length for the second on-time period is proportional, at least for a prescribed range of values for an instantaneous value of the input voltage, to a quotient with a first first-degree function for the instantaneous value in the denominator and a second first-degree function for the instantaneous value in the numerator, with function values for the first function increasing as the instantaneous value rises.

Abstract: A sampling method with adjusting duty ratios is provided and includes the following steps. A first working pulse signal which has a pulse-width duty ratio D in a switching period Ts is provided. A first adjusting period comprising first N successive switching periods of the first working pulse signal is set, wherein N is a natural number larger than 1. A second working pulse signal which has second N successive switching periods with their corresponding pulse-width duty ratio D1, D2, . . . , DN to drive the switch in the converter circuit is provided and the measured signal is generated, wherein the sum of D1, D2, . . . , DN substantially equals to N·D and the second N successive switching periods constitute a second adjusting period.

Abstract: Disclosed is an overload protection delay circuit for use in a switching power supply for enabling the switching power supply to detect overload problems with high accuracy. The overload protection delay circuit is connected between a photo coupler and a pulse-width modulator of the switching power supply, and is consisted of an energy storage device such as a capacitor and a charging controller such as a zener diode. The charging controller is configured to set a limit value for allowing the energy storage device to be charged by an internal current source of the pulse-width modulator when the feedback signal of the switching power supply reaches the limit value. By charging the energy storage device, a time delay is added to the feedback signal so that the pulse-width modulator can accurately activate the internal overload protection mechanism without the interference of load transients.

Abstract: In a conventional reactive-power compensator using a static reactive-power compensator (SVC), there are many cases in which the SVC is operating in a state in which it generates an amount of reactive power equivalent to a large part of its capacity. When an unforeseen large voltage fluctuation occurs in this state, the SVC can not sufficiently generate the amount of reactive power required to mitigate the voltage fluctuation. In some cases, such a voltage fluctuation can not be brought under control. To address this situation, a reactive-power compensator utilizes a reactive-power control apparatus that includes a comparison voltage generator for generating, for a control target voltage and to mitigate voltage fluctuation, a comparison voltage restricted within predetermined limits and obeying a predetermined time-lag characteristic. A differential voltage generator generates a differential voltage that is the difference between the comparison voltage and the control target voltage.

Abstract: A reactive power control apparatus for an AC power system includes a reactive power compensation device, a compensation capacitor device and a compensation capacitor control device. The compensation capacitor control device includes a detection voltage output circuit which outputs a bus detection voltage after the clearing of a voltage drop abnormality, corresponding to the AC voltage of a system bus after the voltage drop abnormality that occurred in the AC power system has been cleared, and a compensation capacitor control circuit which controls the connection status of a compensation capacitor with respect to the system bus. The compensation capacitor control circuit controls the connection status of the compensation capacitor with respect to the system bus, on the basis of the voltage level of the bus detection voltage after the clearing of the voltage drop abnormality.

Abstract: The invention recognizes that filter size can be reduced substantially as power factor is permitted to deviate below unity in systematic ways. Preferred methods of the invention provide specific, computable waveforms that permit use of a minimum filter size given a desired target power factor.

Abstract: Charging time of a capacitor is shortened while avoiding erroneous firing due to distortion of a power supply voltage and sustaining an inrush current at a constant level. In the charge control method of a capacitor in a thyristor converter comprising a thyristor for rectifying an AC voltage, a CPU delivering an on/off control signal to a thyristor driver for driving the thyristor, a voltage detection sensor for measuring the AC voltage and the capacitor charging voltage, and the capacitor connected with a DC circuit, the AC voltage and the capacitor charging voltage are measured by means of the voltage detection sensor, differential voltage between the firing phase voltage of the thyristor and the capacitor charging voltage is determined, and the thyristor is fired only when the firing phase voltage of the thyristor becomes lower than a specified voltage determined from the differential voltage.

Abstract: To conserve power when regulating the output voltage (Vo) of a power converter, no adjustment is made to the converter's pulse width modulation times (Tp, Ts) even if the output voltage is off target (Vtar), provided that the output voltage does not change or is moving towards the target voltage. In some embodiments, the output voltage is not allowed to stay off target for more than a predetermined length of time. In some embodiments, the minimal adjustments are always large enough to overcome ringing (1004).

Abstract: In a control system for a static var compensator that performs phase control of a current of a reactor for each phase by a thyristor and thus controls reactive power, a detecting unit that detects a tertiary harmonic current flowing through each phase of the static var compensator is provided, and on the basis of the tertiary harmonic current flowing through each phase detected by the detecting unit, the thyristor of each phase is controlled so that the quantity of generated tertiary harmonic current of each phase becomes equal, and therefore an outflow of the tertiary harmonic current toward a system can be restrained by an inexpensive method.

Abstract: The invention features a system and approach for minimizing the step voltage change as seen by the utility customer as well minimizing transients imposed on the fundamental waveform of a normal voltage carried on a utility power network when a reactive power source (e.g., capacitor bank) is instantaneously connected to the utility power. The reactive power source is adapted to transfer reactive power of a first polarity (e.g., capacitive reactive power) to the utility power network. The system includes a reactive power compensation device configured to transfer a variable quantity of reactive power of a second, opposite polarity to the utility power network, and a controller which, in response to the need to connect the shunt reactive power source to the utility power network, activates the reactive power compensation device and, substantially simultaneously, causes the shunt reactive power source to be connected to the utility power.

Abstract: A static VAR compensator has several parallel compensation components (K1–K3). To connect the static VAR compensator to an operating voltage (U) the compensation components (K1–K3) are first successively connected to the operating voltage (U) by a control unit (CU) via a series resistor (R). The compensation components (K1–K3) are only connected to the operating voltage (U) without series resistance once the aforementioned connection has been completed.

Abstract: An apparatus has a green compact electrode including a material of a coating formed on a workpiece by a discharge, a power source for supplying a first voltage, a voltage detector for detecting a voltage between the workpiece and the electrode, and a pulse current generator for generating and outputting a pulse current from the first voltage, and for cutting off the output when a predetermined period of time has passed after the voltage is detected to be less than a detection voltage. The pulse current is supplied between the workpiece and the electrode, and the detection voltage is less than the first voltage by 5% to 20% of the first voltage.

Abstract: One embodiment of the present invention is a method to control input to an alternating current (AC) induction motor from a power supply that includes steps of: (a) determining a measure of reactive power (VAR) in two input lines to the motor during a time period; and (b) maintaining an SSR (solid state relay) connected in series between the power supply and the motor in a non-conducting state for a subsequent time period, the length of which subsequent time period is determined by analyzing the measure of VAR.

Abstract: The invention features a system and approach for minimizing the step voltage change as seen by the utility customer as well minimizing transients imposed on the fundamental waveform of a normal voltage carried on a utility power network when a reactive power source (e.g., capacitor bank) is instantaneously connected to the utility power. The reactive power source is adapted to transfer reactive power of a first polarity (e.g., capacitive reactive power) to the utility power network. The system includes a reactive power compensation device configured to transfer a variable quantity of reactive power of a second, opposite polarity to the utility power network, and a controller which, in response to the need to connect the shunt reactive power source to the utility power network, activates the reactive power compensation device and, substantially simultaneously, causes the shunt reactive power source to be connected to the utility power.

Abstract: The novel circuit arrangement is used for the static generation of a variable electric output, as is common in static reactive-power compensation systems. According to the invention, a voltage is applied to a consumer, i.e. to a capacitor and/or an inductor, and a transformer (T) has at least two power-control windings (W1, W2) in a secondary circuit, said windings being connected electrically in series via bridge circuits (B1, B2). In their branches, the bridge circuits contain static switches (BSS1 . . . 4) in an inverse-parallel connection, said switches can be selectively connected or disconnected.

Abstract: A low noise synchronous motor including a permanent-magnet rotor and a stator with at least two pairs of stator poles and corresponding winding further includes an electronic power supply comprising a capacitor that is serially connected to one winding of only one pair of poles to act as a 90° phase shifter. A static switch that is driven by an output of the electronic power device is connected to drive another winding of said two pairs. The static switch is controlled by a sensor detecting the position at the rotor.

Abstract: In a power supply control apparatus for controlling supplying of power from a battery to a load, a power supply switch circuit chip is connected to the load, to turn ON and OFF a connection between the battery and the load. A control circuit chip is powered by the battery to control the power supply switch circuit chip. The control circuit chip is constructed by an internal circuit for controlling the power supply switch circuit chip, a parasitic diode connected in parallel to the internal circuit, and a depletion type MOS transistor connected in series to the internal circuit. Diode characteristics of the parasitic diode and the depletion type MOS transistor are opposite to each other with respect to the battery. That is, in a forward-connected battery state, the parasitic diode and the depletion type MOS transistor are reverse-biased and forward-biased, respectively.

Abstract: Three-phase system comprising a three-phase power source and a three-pole switch, through which the phase terminals of the three-phase power source can be connected to a load network. A reference time detector is present for determining a reference point in time. A drive control circuit is provided for controlling the poles of the switch. The poles of the three-pole switch are switched at controlled times at different intervals with respect to the reference time. The time of the contact touch of the first pole is after 185° plus the maximum anticipated pre-ignition time increased by n times 180° after the zero crossing of the voltage between the first and second pole.

Abstract: A power management circuit for a system that has combined power supplies from an inductively coupled circuit and from a battery comprises voltage sensing circuitry for sensing the voltage of each of the power supplies. A switching arrangement selectively connects one of the power supplies with a user or with plural users. The switching arrangement is controlled by appropriate control circuitry in response to outputs from the voltage sensing circuitry. The power management makes the best use of energy received over the inductive interface to preserve battery lifetime.

Abstract: Method/apparatus for controlling input to an AC induction motor from a power supply that determines a measure of reactive power in two input lines to the motor from the power supply, and uses that measure of reactive power to control an SSR in series between the power supply and the motor. In one arrangement, a voltage difference between the two input lines and a current in one of the lines is used to determine the measure of reactive power.

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: An industrial load, preferably an electric arc furnace or a plant for rolling of metallic materials, is supplied from a three-phase electric ac network. A device for compensation of the reactive power consumption of the load comprises a first compensation device for controllable consumption of reactive power and a second compensation device for generation of reactive power, both connected to the electric power network in a parallel connection with the load. The first compensation device comprises a thyristor-controlled reactor for each of the phases of the ac network. Control equipment is supplied with measured values of sensed amplitude values for voltages and currents.

Abstract: A multiple power factor audio amplifier with a power draw up to a maximum amplifier power draw flowing through at least two power flow circuits with at least one circuit including a power factor corrector electrically connected between the amplifier and input terminals. One embodiment including a power factor corrector sized to provide a first output less than the maximum amplifier power draw of the amplifier and a high output power factor bypass adapted to provide a second output to supplement the first output when the amplifier power draw exceeds the first output. Also described are methods for controlling the amplifier demand power factor including adjusting the draw of a first portion of the direct current power at a first level to improve the power factor of an input demand at the rectifier to provide a first part of the demanded amplifier power; and transferring a second portion of the direct current power without power factor correction to provide a second part of the demanded amplifier power.

Abstract: A phase shifter is disclosed in which parasitic elements in a microelectromechanical system (MEMS) switch are designed and utilized to provide a predetermined phase shift. In one embodiment, a circuit containing three MEMS switching modules, each of which includes a pair of series-coupled reactances is described. The first reactance is determined by an inductor, the second by a capacitor representing the MEMS switch contact in either the up or down positions, and wherein the capacitive reactance is greater than the inductive reactance for the MEMS switch contact in the up position and less than the inductive reactance for the MEMS switch in the down position. The three MEMS switching modules are configured such that a switched high pass/low pass phase shifter topology can be realized with the appropriate actuation of the MEMS switch contacts.

Abstract: An industrial load, preferably an electric arc furnace or a plant for rolling of metallic materials, is supplied from a three-phase electric ac network. A device for compensation of the reactive power consumption of the load comprises a first compensation device for controllable consumption of reactive power and a second compensation device for generation of reactive power, both connected to the electric power network in a parallel connection with the load. The first compensation device comprises a thyristor-controlled reactor for each of the phases of the ac network. Control equipment is supplied with measured values of sensed amplitude values for voltages and currents.

Abstract: A method for controlling fault interruption in a high voltage electrical energy transmission system semiconductor high voltage electrical energy transmission switching system which includes a multiple stack of power semiconductor SCR thyristor circuit sections arranged for single phase or three-phase operation with each section of the stack comprising; a pair of input and output terminals, a plurality of switching thyristors connected in series between the input and output terminals, an auxiliary power transformer having at least three windings with first and second windings interconnecting the input and output terminals of one section to the respective output and input terminals in each adjacent section of the stack such that the voltage difference between the first and second transformer windings is limited to the maximum voltage across the section.

Abstract: A multiple power factor audio amplifier with a power draw up to a maximum amplifier power draw flowing through at least two power flow circuits with at least one circuit including a power factor corrector electrically connected between the amplifier and input terminals. One embodiment including a power factor corrector sized to provide a first output less than the maximum amplifier power draw of the amplifier and a high output power factor bypass adapted to provide a second output to supplement the first output when the amplifier power draw exceeds the first output. Also described are methods for controlling the amplifier demand power factor including adjusting the draw of a first portion of the direct current power at a first level to improve the power factor of an input demand at the rectifier to provide a first part of the demanded amplifier power; and transferring a second portion of the direct current power without power factor correction to provide a second part of the demanded amplifier power.

Abstract: The invention features a system and approach for minimizing the step voltage change as seen by the utility customer as well minimizing transients imposed on the fundamental waveform of a normal voltage carried on a utility power network when a reactive power source (e.g., capacitor bank) is instantaneously connected to the utility power. The reactive power source is adapted to transfer reactive power of a first polarity (e.g., capacitive reactive power) to the utility power network. The system includes a reactive power compensation device configured to transfer a variable quantity of reactive power of a second, opposite polarity to the utility power network, and a controller which, in response to the need to connect the shunt reactive power source to the utility power network, activates the reactive power compensation device and, substantially simultaneously, causes the shunt reactive power source to be connected to the utility power.

Abstract: A series compensator, connected in series to an AC transmission line, for compensating for an electric amount, such as a voltage, current, phase or impedance, of the AC transmission line, comprises a first capacitor and a second capacitor connected in series to each other and connected to the AC transmission line, and a compensation current generator connected in parallel to the first capacitor. This structure eliminates the need for a bypass transmission line to simplify the main transmission line structure, has an enhanced current controllability, reduces harmonics to be generated and realizes an economical way of ensuring a large compensation amount.

Abstract: A supply device (FD1, FD2) for power supply to an electronic unit (EU1, EU2) for a controllable semiconductor element (T1, T2) in a semiconductor valve in a shunt-connected thyristor-switched capacitor (CA). The capacitor being intended to carry an alternating current with a known period (T), the semiconductor valve comprising a snubber circuit (SC) with a first and a second terminal (CS1 and CS2, respectively) only. The supply device has an energy storage (C1, C2) for storing electrical energy, a valve terminal (J13, J23), a snubber terminal (J12, J22), a supply terminal (J11, J21) connected to the energy storage and a first current path from the snubber terminal to the supply terminal. The energy storage is designed to store an amount of energy which is larger than the energy requirement of the electronic unit during one cycle of the alternating current but smaller than its energy requirement during two cycles.

Abstract: A controller for generating a modulation signal m applied to a transformerless reactive series compensator connected serially in a power transmission line. A modulation signal generator generates a modulation signal m in the form of m=md cos (&ohgr;t)−mq sin (wt). The controller includes a current control loop with a current controller outputting the modulation index mq of the modulation signal m. A voltage control loop including a DC voltage controller outputs the modulation index md, of the modulation signal m. The current control loop and the voltage control loop are respectively provided for outputting indices mq′, md′ in order to control a line current and a DC capacitor voltage of a capacitor of the compensator to reference values. The controller includes a decoupler so that the line controller and the capacitor voltage are independent of the output of the current controller.

Abstract: A method and apparatus are provided directed to a synchronous and adaptive capacitor switch controller for minimizing transients in the power factor correction of an electric power distribution system or transmission line. In particular, a capacitor, operatively associated with an electrical bus for distributing electric power, is provided for varying a capacitance on the electrical bus to perform power factor correction. A mechanical switch having a variable switch delay is provided for electrically connecting and disconnecting the capacitor to the electrical bus. A disturbance detector for measuring a voltage disturbance on the electrical bus upon connection and disconnection of the capacitor is further included.

Abstract: A device for compensation of the reactive power consumption of an industrial load, preferably an electric arc furnace or a plant for rolling of metallic materials, supplied from a three-phase (a, b, c) electric ac network, comprises a first compensation device for controllable consumption of reactive power and a second compensation device for generation of reactive power. The first compensation device comprises an inductor connected in series with a semiconductor connection controllable in dependence on a control order (.alpha.ref) supplied thereto. Control equipment is supplied with measured values of voltage (Ua, Ub, Uc) and current (Ia, Ib, Ic), respectively, at the load. The control equipment comprises devices for determination of the instantaneous consumption of active and reactive power by the load, and a control device which forms the control signal to the first compensation device in dependence on the consumption of reactive power and active power by the load.

Abstract: The invention relates to a compensator device connected in series to power transmission lines and including at least one compensator unit with a transformerless reactive series compensator. The compensator unit includes an AC switch coupled to output terminals of the series compensator. Furthermore, the invention also relates to such a compensation device including multiple compensator units connected in series at the output terminals and a continuous operation control for selectively controlling the series-connected compensators. With such a compensation device, the transformerless reactive series compensator can be prevented, by the AC switch, from conducting an overcurrent and the main components of the compensation device can be compact.

Abstract: This invention relates to a method for measuring the electrode-related electric quantities of an AC electric-arc furnace. The method is based on observing the mutual correlation between electrode currents and total power supplied into a furnace by utilizing the fast, natural fluctuation of currents and power supplies into a furnace, and on estimation observations. The information required in estimation is collected by performing a plurality of successive current and voltage measurements at adjacent instants and at various energy distributions of a furnace. The measurement results are used to calculably determine the estimates for electrode-related voltages, impedances and powers. It is further possible to split the electrode-related powers and voltages on the one hand in the electric-arc power and voltage and on the other hand in the power and voltage loss caused by resistive conduction. The effect of mutual impedances is automatically taken into account in estimation.

Abstract: A compensation device connected in series with power transmission lines having at least one circuit breaker and including at least one compensator unit with a transformerless reactive series compensator having a DC capacitor and a single-phase inverter. A pre-charger pre-charges the DC capacitor of at least one compensator unit. The pre-charger may decouple the DC capacitor from the power transmission lines during pre-charging. The pre-charger may include an AC switch and an AC switch controller opening the AC switch for a time interval (alfa) after a zero-crossing of the line current.

Abstract: An audio amplifier for receiving input current and sinusoidal line voltage from an AC source, and delivering audio output power to a load includes: a power factor correction circuit for receiving the line voltage from the AC source, the power factor correction circuit including a control circuit operable to cause the wave shape of the input current drawn from the AC source to substantially correspond to the wave shape of the line voltage by producing an intermediate source of voltage at a substantially higher potential than the line voltage of the AC source; a DC power supply coupled to the power factor correction circuit and operable to convert the intermediate source of voltage into a regulated DC source of power; and an audio power amplifier coupled to the DC power supply and operable to convert the DC source of power into the audio output power for delivery to the load.

Abstract: A device for control of a capacitor device for a shunt-connected static compensator unit (COM1, COM2, COM3) for compensation of reactive power in an electric power network (NW). The capacitor device comprises a capacitor and a semiconductor valve, connected in series with said capacitor, with a first semiconductor, corresponding to respectively a first and a second conduction direction for current through the capacitor. The device comprises members (VN, FSD, CU) which, in dependence on a voltage (Uab, Ubc, Uca) sensed at the compensator, alternately generate a firing order for the respective semiconductor. In addition thereto, the device comprises members which, for each of the first and second conduction directions, form a deblocking signal, indicating that the conduction direction associated with the respective firing order does not carry current, and which thus generate a firing order for the second of the first and second conduction directions with an optional delay (T1*f*360.degree.

Abstract: A transient reducing capacitor switching device that switches grounded capacitors into a multi-phase power line, wherein each phase of the line carries an AC voltage signal that cycles its polarity. A first switch is associated with a first grounded capacitor, a second switch is associated with a second grounded capacitor and a third switch is associated with a third grounded capacitor. A switch controller switches the first capacitor into the first phase of the power line substantially when the voltage signal in the first phase crosses zero potential. The switch controller has a delay that delays at least one-quarter of one cycle after the first capacitor was switched into the first phase, then switches the second capacitor into the second phase of the line substantially when the voltage signal in the second phase crosses zero potential.

Abstract: A compensation control device for a power system includes a switched capacitor connected in series with a transmission line, a voltage applying control connected in series with the transmission line, and a ganged control for controlling on/off operation of the switched capacitor and a linearizing voltage generated by the voltage applying control. The control ensures that a sum voltage of a stepped voltage generated across the switched capacitor and the linearizing voltage produced by the voltage applying control and that is applied to the transmission line is continuous. The control device realizes controllability of the total impedance of the transmission line and reduces the capacitance of the parts employed in the ganged control.

Abstract: In an apparatus for control of controller equipment for damping power oscillations in a power line, the controller equipment is serially connected between a first connection point and a second connection point in the power line in an electric network for alternating current. The controller equipment is adapted to serially generate in the power line, dependent on a control order, a damping voltage for damping power oscillations in the power line. Controlling equipment receives sensed quantities of the power network and forms a phase deviation dependent on these quantities. The phase deviation is the difference between a phase angle of a first voltage at the first connection point and a phase angle of a second voltage at the second connection point. The controlling equipment forms the control order dependent on the time rate of change of a function of the phase deviation.

Abstract: A thyristor-controlled capacitor bank includes a thyristor switch and a capacitor bank. The capacitor bank is split into at least two series-connected capacitor groups. A series circuit including a thyristor switch and an inductor coil is connected in parallel with the capacitor group which is remote from a capacitor group at a mains power supply connection. A thyristor-switched capacitor bank is thus obtained which has a thyristor switch that therefore only needs to be constructed for a fraction of the mains power supply voltage itself, which is a major advantage for economic reasons.

Abstract: Series voltage compensation is provided in an ac power line by connecting the inverter unit of a dynamic voltage restorer (DVR) in series with the primary winding of a load transformer, which may already be present, thereby eliminating the need for injection transformers. For three-phase ac power lines the three primary phase windings can be either wye or delta connected. If they are wye connected, a three-phase inverter with a common dc source is preferred. For delta connected primary phase windings, separate single-phase inverters each with its own floating dc source can be directly connected in series with each primary phase winding. Preferably however, the poles of a two-phase inverter are direct connected in series between two of the primary phase windings and a common source phase, and share a common dc source referenced to the common source phase.

Abstract: A VAR generator compensation system wherein the voltage of the capacitor or reactor bank is changed as a means of adjusting the phase angle is taught. Briefly stated a reactive bank such as a capacitor bank is connected to the secondary of an autotransformer such that the voltage of the reactive bank is controlled by the autotransformer. The line and load are connected to the primary of the autotransformer, such that changing the voltage of the autotransformer and hence the secondary voltage connected to the reactive bank, thus changes the VARS generated on the grid or system.