Siemens Aktiengesellschaft

Hermann Waldmann

Michael Becker

Klaus Renz

Dusan Povh

Alfons Fendt

Gerhard Schuch

Manfred Weibelzahl

Wolfgang Meusel

Herbert Auinger

Wolfgang Kaufhold

Kurt Fork

Bernd Gortz

Ludwig Filberich

Heinrich Blau

Werner Grohmann

Dusan Pove

Heinrich Bonig

Manfred Erche

Heribert Niebergall

Synchronous machine having control coils for compensating mechanical

An arrangement for generating in each switching panel of a multipanel switching facility of an electrical power distribution network a digital operating-state image derived from command inputs and switching position signals. The digital operating state image is transmitted to a collecting memory arranged in a coupling panel which produces an overall image of all switching panels; which overall image is transmitted to the individual switching panels at periodic time intervals. A checking procedure is then conducted in the individual switching panels using the overall image. The arrangement utilizes microprocessors which are coupled to one another so as to exchange data via several transmission paths which are one-bit wide. This arrangement obviates the need for an interlock cable harness in the switching panels and cross-cabling between the switching panels.

System for error-protected operation of multipanel, power distribution

A monitoring system for detecting earth contact of at least one phase of a polyphase network. Each of the phases in the network is connected by a capacitive-inductive filter to a neutral node which is connected to earth. In one embodiment of the invention, the current flowing from the neutral node to earth is detected by an induction current transformer which provides a signal responsive to said earth current. The output signal of the induction current transformer is conducted through at least one low pass filter for suppressing harmonics, and rectified to produce a direct current voltage signal, the amplitude of which is proportional to the amplitude of the fundamental frequency component of said signal. A fault indicating signal is produced when the direct voltage signal exceeds a predetermined value.

Earth contact monitoring device for a polyphase three-phase filter

A system for monitoring the capacitor batteries of a three-phase filter circuit. Each capacitor battery is formed of a plurality of parallel legs each having a plurality of sectional capacitors which are connected in series with fuses. Adjacent ones of the sectional capacitors are coupled to one another. In a three-phase system, three capacitor batteries are coupled to one another in a Y-circuit configuration, the Y-circuit node being coupled to a reference potential, illustratively ground. The magnitude and phase of the fundamental frequency component of the current flowing from the Y-circuit node to the reference potential is monitored, variations therein being evaluated to identify defective sectional capacitors. Only variations in the Y-circuit node current which occur rapidly will trigger fault signals, thereby preventing false indications resulting from variations in temperature.

Monitoring system for the capacitor batteries of a three-phase filter

A monitoring system for measuring the phase currents of a filter circuit, the monitoring system having current measuring transformers coupled to respective filter sections for suppressing the harmonic content. Voltage measuring transformers are provided for measuring the network phase voltages, each such voltage measuring transformer being coupled to an electronic filter simulator and a filtering section for suppressing harmonic content. The fundamental frequency component of the measured phase currents and the simulated phase currents are conducted to transient comparator circuitry which is coupled to indicating and triggering circuitry having individual counter stages. Only rapid variations between the measured and simulated phase currents will result in fault indications, thereby preventing false indications resulting from variations in temperature.

Monitoring system for an LC filter circuit in an AC power network

A circuit for damping hunting oscillations of controlled electric machines. The circuit is provided with a measuring circuit for determining the hunting oscillations and an identifier circuit for determining the angle components of such hunting oscillations. A phase shifter circuit is provided for receiving the angle components produced by the identifier circuit and forming a hunting oscillation correction signal which is shifted in phase from the hunting oscillations by a predetermined phase angle. The hunting oscillation correction signal is conducted to a control unit of the electric machine. The invention is particularly useful in damping hunting by the rotors of voltage controlled synchronous generators.

Circuit for damping hunting by electric machines

A circuit for monitoring the voltage stress of a capacitor which produces an over-stress indicator signal responsive to the over-voltage history of the capacitor. If the measured voltage stress of the capacitor exceeds a predetermined over-voltage value, a characteristic-curve generator, having a predetermined transfer function, produces an output signal which is responsive to the measured voltage stress of the capacitor and the transfer function of the characteristic-curve generator. This signal is combined with a further signal which is responsive to a predetermined permissible continuous operation voltage value. The combined signals are conducted to an integrator having a predetermined integration time constant for producing an overload signal. The overload signal at the output of the integrator is a measure of the state of stress of the capacitor. Circuitry may be provided for disconnecting the capacitor from a transmission line in response to the output signal of the integrator. Also, plural capacitor voltage stress monitoring stages may be combined to monitor the capacitor voltage stress in a plurality of over-voltage ranges.

Circuit for monitoring the voltage stress of a capacitor

A method for the transmission of DC current via a DC network between at least one rectifier station and several inverter stations wherein reference inputs are formed on the basis of a fixed predetermined current-voltage characteristic and a fixed predetermined voltage-current characteristic matched to the aforesaid current-voltage characteristic for the voltage controller of the rectifier of the rectifier station and for the current controller of each inverter station, respectively. The formed reference input for each current controller is released to that current controller when the maximum value of the formed reference input exceeds a value determined for the reference input corresponding to the power demand associated with the inverter station which includes that current controller. When the maximum value of the formed reference input is less than the latter determined value, such value is released as the reference input to the current controller.

Method for the transmission of DC current between at least one rectifier

A circuit arrangement is disclosed having an odd number of Y-connected frequency converters. The control units of the frequency converters are associated with current regulators, all of which are addressed by an additional common reference value. In accord with the invention, the aforesaid reference value is derived by generating a difference voltage corresponding to the difference of the voltages at the neutral point of the frequency converter circuit and the neutral point of the load. This difference voltage is then passed through a delay member whose time constant corresponds to the time constant of the load to develop the reference value.

Circuit arrangement with a number of frequency converters, particularly

A method and apparatus for the static compensation of reactive power using controlled reactive power converters having control variables derived from the phase load currents in which the phase load currents are converted into a line frequency oscillation and two rotating current vectors derived from each of the line frequency components, with the current vector components then transformed into d-c quantities by addition to a system vector to form a co-rotating and counter-rotating vector, from the components of which control variables of the reactive power converter are formed.

Method and apparatus for the static compensation of reactive power

An improved arrangement for regulating the speed of an asynchronous motor in which an real performance regulator is inserted between the speed regulator and the means controlling the input voltage and/or current to the motor. The subsidiary regulator inserted between the speed control and the motor control circuits receives as an input a value of the real power which is proportional to the torque or traction force thereby resulting in linear control of the motor based on its actual performance.

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Weiher, Germany

Hermann Waldmann