Siemens Aktiengesellschaft

Georg Wild

Manfred Weibelzahl

Wolfgang Kaufhold

Kadry Sadek

Karl-Friedrich Leowald

Helmut Neupauer

Johann Messner

Franz-Wolfgang Bendl

Martin Haushofer

Rembert Kohler

Vladimir E Henner

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 high-voltage d-c transmission system in which one of the converters is operated as a rectifier and the other as an inverter. A first cascade control which sets the rectifier control angle includes a superimposed active power controller and a subordinated d-c controller. A second cascade control which sets the inverter control angle includes a superimposed voltage/active power controller, a superimposed quenching angle control and a subordinated quenching angle controller. The setting signal of each of the two superimposed controllers are controlled in dependence on the control deviation of the other one of the superimposed controllers via a first or second pilot control for decoupling the cascade controls. The gain factors of the pilot control quantities depend on the operating point in such a manner that a small engagement of the pilot control variable exists for small control angles and a large engagement exists for large control angles.

Method and apparatus for decoupling the active and reactive power

A state signal is formed to indicate a transition to a bypass mode of operation. In forming the signal of each winding system of a corresponding converter transformer on a side of the converter transformer are determined, weighted with weighting factors and summed up. The summation current formed in this manner does not have any null zones in the normal operation of the converter. All weighting factors are different if the phase currents between the converter and the converter transformer are used to produce the summation current. In the case of a converter transformer which is connected to the converter via a delta-connected winding system and in which the winding currents are used, certain differences formed by the weighting factors are not to be the same. A DC Hall converter with an insertion hole is particularly well suited for weighting and combining the currents of each individual winding system.

State signal formation for indicating the transition into the bypass

Upon the occurrence of a change of an a.c. voltage amplitude of an a.c. power network line in one station A, a computing element generates a first pilot control variable by means of which the control angle of the respective static converter is shifted in terms of a reduction of its d.c. output voltage. In the other station a voltage correction regulator generates a correction variable by compensating the voltage drop in the HVDC transmission line, by means of which the control voltage of the respective static converter is corrected, which, for example, is generated by a pilot control voltage and the output signal of a marginal current or extinction angle regulator. Thus, even in case of an a.c. power network fault-induced voltage dip of the HVDC voltage, a preset value can be maintained for the HVDC current and the voltage dip in the power transmission be reduced. This procedure is independent of which station is operated as rectifier and which as inverter.

Procedure and device to operate an HVDC transmission short coupling in

If in a high-voltage d-c transmission system (HVDCTS), a resonance frequency of an a-c voltage network (NB) connected to the inverter (1B) is located in the vicinity of a voltage component contained in the a-c voltage network, a resonance frequency which often cannot be compensated by a current regulator controlling the rectifier stage (1A) is coupled into the d-c circuit of the HVDCTS via the inverter. Therefore, resonance phenomena which requires an emergency shutdown of the HVDCTS are generated. Therefore, a pilot quantity (U'.sub.d) is formed with a defined phase shift relative to the resonance oscillation of the HVDCTS voltage and added to the output of the current regulator. Thereby, a constant HVDCTS current can be generated for a given operating point and the resonance in the a-c voltage network (NB) can be damped. If the resonance oscillation is determined by two quantities (U'.sub.d, i'.sub.d) of, respectively, the HVDCTS voltage as well as of the HVDCTS current, stable damping of the resonance phenomena can be achieved by the pilot control described with the two quantities even for deviating operating points.

Method and apparatus for suppressing resonance phenomena in the A-C

A method and apparatus are described for operating a high voltage d.c. (HVDC) transmission line system connecting two a.c. transmission line systems during normal operation and during malfunction in either the rectifier station or the inverter station of the HVDC system. When a malfunction exists in one station of a HVDC transmission line, such as a rectifier station, then the regular thyristor firings are disabled and a bypass circuit, preferrably one or several bridge paths of a converter, are fired. As soon as a corresponding change in the current or voltage occurs at the d.c. voltage connections of the other station, this station assumes rectifier operation during which the HVDC transmission line is utilized as a reactive load to stabilize the other system. Once the malfunction has ceased to exist, operation is first resumed in the first station by extinguishing the bypass thyristors and subsequently resumed also in the other station. This procedure permits stable normal operation in both stations, or bypass operation without using remote control signals during which the HVDC transmission line can be rapidly controlled to stabilize the systems.

Growing community of inventors

Langensendelbach, Germany

Georg Wild