Siemens Aktiengesellschaft

Siemens Aktiengesell Schaft

Karl-Friedrich Leowald

Jakob Schenk

Stephan Weiss

Oskar Beckmann

Adolf Habock

Georg Wild

Stefan Frese

Franz Mayerhofer

Herbert Radda

Vladimir E Henner

Manfred Hoffmann

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.

Method and apparatus for generating a synchronizing signal for a

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.c), and this series compensator is able to be brought into such a state that disadvantages are avoided for the network operation, through which means the availability of the system and the quality of the compensation are increased.

Method and apparatus for recognizing defects in a triggering system of a

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.

Method and apparatus for symmetrically modulating a controlled series

When there are variations in the short-circuit power of a system, the operating conditions can change, particularly in a controller of a compensating device. To automatically adapt the controller and to avoid or suppress oscillations or voltage variations in the system, a method is provided according to a first solution, where the circuit state of a compensating element is modified for testing purposes. The reaction of the system is detected in a device and, then a parameter which determines the damping of the controller is modified by means of a computing device. According to a second solution, an oscillation of the controller is established by detecting a signal which is dependent on the system voltage and by comparing specific variations. To suppress the oscillations, the hysteresis of the controller is damped by means of the computing device.

Methods and device for stabilizing an electric supply system through the

A protection circuit for protecting the thyristors of a series circuit of several thyristors, each of which has a corresponding firing circuit to which its anode-cathode voltage is applied. The protection circuit comprises: a plurality of first monitoring means, each of which first monitoring means is associated with and at the potential of a different one of said thyristors, and each of which monitoring means generates a first switching signal when either the current carried by its associated thyristor becomes zero or the voltage across its respective thyristor falls below a predetermined negative value; a plurality of first potential-separating transmission means, each of which first transmission means transmits a different one of said first switching signals; an evaluating means; a plurality of second, potential separating transmission means; a plurality of second monitoring means, each of which second monitoring means is associated with and at the potential of a different one of said thyristors, and each of which second monitoring means generates a second switching signal when the voltage across its associated thyristor exceeds a predetermined positive value; and a plurality of logic circuit means each of which is adapted to feed a signal to the firing circuit associated with a different one of said thyristors when the second switching signal generated by the second monitoring means associated with that one thyristor appears during the timing signal transmitted by the second transmission means associated with that one thyristor.

Protection circuit for serially connected thyristors

Apparatus for firing the thyristors or valves in parallel connected first and second valve branches. More particularly, a firing device is provided for providing firing pulses to at least a first valve in the first valve branch. A refiring device is provided which includes a transformer for determining the difference in the current carried by the first valve and a second valve adjacent thereto in the second valve branch. The latter refiring device also comprises a threshold member which, when the current difference determined by the transformer exceeds a predetermined value, causes the one of the first and second valves carrying the lesser current to receive firing pulses.

Circuit arrangement for firing controlled, parallel-connected electric

The invention concerns a circuit arrangement for firing a controlled semiconductor valve, particularly a thyristor, the control path of which is connected to a d-c voltage source by way of the collector-emitter path of a transistor. In order to obtain a control electrode current at the semiconductor valve, which is independent of the d-c voltage of the d-c voltage source and the control electrode characteristic of the semiconductor valve, provision is made, according to the invention, that a resistor is arranged in series with the collector-emitter path of the transistor, and that a Zener diode is connected between the base of the transistor and that terminal of the resistor which is facing away from the transistor.

Circuit arrangement for firing a controlled semiconductor valve,

The invention concerns a circuit arrangement for firing an electric valve, particularly a thyristor, with a pulse capacitor which can be charged from the a-c voltage at the anode-cathode path of the electric valve by means of an external resistor and can be discharged by means of a contactless switching device for firing the electric valve by way of its control path. To increase the firing performance, there is provided in parallel to the anode-cathode path of the electric valve a series circuit comprising an external resistor and the primary winding of a transformer the secondary winding of which is connected to the pulse capacitor by way of a rectifier.

Firing circuit for an electric valve

The invention concerns a circuit arrangement for the wireless transmission of control signals to the control paths of controlled semiconductor valves, particularly of thyristors, which are preferably usable in a rectifier for high voltage. The control signals are provided for the modulation of a high-frequency transmitter which is disposed at some distance from high frequency receivers each containing a demodulator, whose output signal is delivered to the control path of a semiconductor valve. In order to ensure reliable and interference-proof firing of the semiconductor valves, if the distance between the high-frequency transmitter and the high-frequency receiver is large, there is provided, a frequency-modulated high-frequency transmitter as the high-frequency transmitter. The carrier frequency of the frequency modulated transmitter is in the range of 10 MHz to 50 GHz and has a transmitting antenna provided with a reflector which is directed toward receiving antennas with which the individual high-frequency receivers are equipped. The demodulator contained in each high-frequency receiver comprises a filter which is tuned to the modulation frequency associated with the control signal (p2, p5) which substantially blocks the passage of other frequencies.

Circuit arrangement for the wireless transmission of control signals to

The invention concerns a firing device for a number of electric valves, particularly thyristors. Each thyristor control path is associated with a firing circuit with a detector for electromagnetic radiation responsive to a transmitter which is controlled by a firing control signal and is equipped with a radiating device which energizes the individual detectors. The detectors are arranged close together in a plane perpendicular to the radiation direction of the radiator. In order to obtain latitude in the arrangement of the detectors, the radiator is designed so that it furnishes a parallel-ray bundle of radiation and the detectors are spatially arranged relative to each other, such that they are exposed to the parallel ray bundle without mutual shadowing upon projection in the direction of the radiation on a projection plane which is perpendicular to the radiation direction.

Firing apparatus for a plurality of electric valves

The invention relates to a circuit arrangement for the simultaneous ignition of a plurality of thyristors. Control paths of the thyristors are each connected to a secondary winding of a pulse transformer by way of a separate full-wave rectifier, an alternating current of higher frequency being supplied to the primary winding of the pulse transformer by a control current amplifier. In order to obtain a continuous flow of control current when a control signal is given, it is provided, according to the invention, that there is connected to the control path of each thyristor the series arrangement of a storage reactance coil and an uncontrolled diode poled in the direction of the gate current, and that the output of the full-wave rectifier is connected to this uncontrolled diode.

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Weiher, Germany

Karl-Friedrich Leowald