Abstract: A static VAR generator utilizing a multitude of reactor banks each having different computation circuits and firing angle control circuits is provided. The different computation and firing angle control circuits allows the VAR generator the flexibility of being able to change the reactor power in an A.C. network repetitively in any cycle in response to rapid changes in load demand. This is accomplished by each reactor bank having progressively longer computation times and later insertion of additional banks into the network after the first bank has responded to load demand.

Abstract: In an unrestricted frequency changer (UFC) the control pulses are generated by the intersection of a reference ramp of controllable slope and frequency with a succession of timing ramps characterizing the succession of phase voltages at the input of the UFC, whereby by increasing the slope and exceeding the peaks of the timing waves the sinusoidal shape of the output becomes trapezoidal and by increased slope increasingly close to a square-shaped wave, thus maximizing the output voltage at high frequency of operation.

Abstract: In a static frequency changer controlled by adjusting the time of conduction of the bilateral switching units forming static converters, the time of conduction is split into n time intervals of conduction of respective subdurations adding-up to be equivalent to the effective time of conduction of the controlled switching unit, and such subdurations are spread and distributed throughout the time period of control of the switching unit within the original switching pattern of the converters, thereby to improve the quality of the output and input currents.

Abstract: An auxiliary thyristor control circuit inserts a zinc oxide varistor in series with the capacitor bank of a static VAR generator for discharging the capacitor bank when the static VAR generator is subjected to high transient voltages.

Abstract: There is provided a static VAR generator having voltage regulation in combination with the capability to damp subsynchronous resonance should it occur. A novel method for controlling subsynchronous resonance is provided by monitoring the frequency of the electrical generating system and controlling the insertion of compensating inductance in response to disturbances that may result in voltage and frequency pulsations.

Abstract: a multiphase AC current of one frequency is converted to a multiphase current of another frequency by a frequency changer having its output terminals terminated by a load having the impedance characteristics of a voltage source. In this arrangement the multiple phases of a practical AC current source such as a synchronous generator are connected directly to each load phase, even where the bidirectional switches of the UFC are arranged in pulse groups or a bridge configuration.

Abstract: There is provided a static VAR generator having a novel method for controlling subsynchronous resonance by monitoring the frequency of the electrical generating system and controlling subsynchronous resonance by phase-firing thyristor controlled inductance.

Abstract: There is provided a static VAR generator generally comprised of a fixed capacitor bank and a first and second switched conductor bank whereby said second switched inductor bank is operated at voltages leading the first inductor bank by 30 electrical degrees to allow the VAR generator to adjust its output current twice in each half cycle of operation.

Abstract: There is provided by this invention a novel high power resonance filter utilizing a resistive element between two resonant branches disposed to dampen resonant harmonic currents or voltages while maintaining minimal losses at the fundamental frequency.

Abstract: There is provided by this invention a static VAR generator having an auxiliary shutdown firing pulse generator that initiates a thyristor controlled inductive current to cancel only capacitive current supplied by the static VAR generator in the event of failure of the VAR generator's control means monitoring the capacitive current requirements.

Abstract: There is provided by this invention a static VAR generator having an auxiliary shutdown firing pulse generator that initiates a thyristor controlled inductive current to cancel any capacitive current supplied by the static VAR generator in the event of failure of the VAR generator's control means monitoring the capacitive current requirements.

Abstract: A voltage regulator is taught for maintaining the terminal voltage of a three phase transmission line at a fixed reference value. The voltage regulator system utilizes the reactance of the transmission line in conjunction with reactive current from a VAR generator to compensate for the voltage effect of line current as it flows through the line reactance. The VAR generator is of the parallel capacitor-inductor type where the inductor is controlled by a thyristor switch. The conduction of the thyristor is controlled by utilizing a control system which generates an error signal based on the half period average of line voltage. The error signal is converted to a signal which is proportional to flux linkages by an integrator and then compared with the integral of the voltage signal for determining the conduction angle of the thyristor switches.

Abstract: A VAR generator of the switched capacitor controlled reactor type is shown utilized for a power transmission system. The control arrangement is such that the thyristor controlled capacitor and reactor banks are kept switched out for small terminal voltage variations which can be tolerated without compensation in order to minimize standby or no load losses in the region of the nominal voltage of the transmission system. Outside of this region VAR compensation is provided.

Abstract: When the input frequency is below a preselected value, an unrestricted frequency changer (UFC) is operated in the conventional manner by sequentially switching to more positive input phases while the fundamental component of the output waveform is positive going and to more negative input phases while it is negative going. Above the preselected input frequency, the UFC is operated in a complementary manner; that is, by switching to more negative input phases while the output waveform fundamental component is positive going and to more positive input phases when it is negative going. The switching instants occur in UFC operation when the reference waveform is equal in amplitude but opposite in slope to each waveform in a set of timing waveforms phase locked to the input waveforms. During complementary UFC operation, switching occurs when the reference waveform is not only equal in amplitude to the timing waveforms but also has a slope of the same sense.

Abstract: The input power factor of an AC to AC static power converter is continuously adjustable between a maximum leading or lagging phase angle, determined by the load power factor, through rapidly transferring between conventional and complementary unrestricted frequency changer operation with the proportion of each sub generator cycle interval dedicated to each mode of operation being selected to produce the desired input power factor. Since the input power factor affects generator excitation, the input power factor control can be used in a closed loop feedback control system to regulate generator voltage.

Abstract: This invention discloses a novel means of inserting capacitance into an AC network for power factor correction or voltage regulation that minimizes and transient disturbances to the system. Current surges and voltage transients that are normally associated with connection of capacitors into an AC network is minimized by predetermining an amount of inductance that must be inserted to suppress these transients and simultaneously inserting the inductance into the network with the capacitance.

Abstract: A control system for a VAR generator is taught in which a thyristor controlled inductive element is used to provide lagging VAR's and a bank of parallel capacitors, each of which may be switched into and out of circuit cooperation independent of the other, is used to provide discrete levels of leading VAR's. The inductive element is utilized in conjunction with the discrete levels of leading VAR's to provide a continuum of VAR generation in the region between the discrete levels by providing continuously variable compensating or cancelling current for interaction with the discrete levels to provide an overall continuous range of VAR generation in the leading VAR region.

Abstract: Electrical apparatus such as a VAR generator or convertor is taught for high-voltage application. The electrical apparatus includes series stacked silicon controlled rectifiers, some of which operate at high electrical potential. Switching information is provided to the thyristors by way of insulating light pipes. The energy for actuating the gate of the thyristor in each case is provided by a current transformer which in some instances is interconnected with the anode of the thyristor in question to monitor the anode current thereof in a previous half cycle of conduction. In other instances, anode current of another thyristor are monitored. The anode current is converted to stored charge which is later released through a light actuated switch to the gate for energization of the thyristor in question. This means that a thyristor may be repeatedly energized even after many intervals of full cycle conduction where no anode to cathode potential is available for charging a capacitor.

Abstract: A voltage regulator and flicker compensator is taught which utilizes a simulated light bulb in the feedback control. The simulated light bulb utilizes an analog voltage squaring module the output of which is filtered to reduce the second harmonic of the input signal. An error generator is provided as part of the control loop. The error generator utilizes an adaptive voltage reference which tends to conserve VAR generator capacity. A voltage preconditioner is also utilized which reduces spurious non-flicker transients and the like in the feedback signal.

Abstract: A VAR generator is taught in which a thyristor controlled inductive element is used to provide lagging VAR's and a bank of parallel capacitors, each of which may be switched into and out of circuit cooperation independent of the other, is used to provide discrete levels of leading VAR's. The inductive element is utilized in conjunction with the discrete levels of leading VAR's to provide a continuum of VAR generation in the region between the discrete levels by providing continuously variable compensating or cancelling current for interaction with the discrete levels to provide an overall continuous range of VAR generation in the leading VAR region.