Abb Technology Ag

Abb Ab

Asea Brown Boveri Ab

Asea Brown Boveri Inc.

Abb Schweiz Ag

Krister Nyberg

Hans Björklund

Gunnar Asplund

Roland Siljeström

Urban Åström

Hans Bj&ouml;rklund

Urban &angst;str&ouml;m

Urban Strom

Roland Siljestr&ouml;m

Tommy Segerbäck

Urban Strangm

Ari Seppanen

A device for sensing a binary signal includes a device configured to measure a signal level of the signal, a device configured to determine whether the measured signal level is 'low' or 'high', a device configured to provide a variable input impedance, and a device configured to control the input impedance in response to the measured signal level. The variable input impedance may be provided by way of a transistor and a resistor, and by controlling the duty ratio of the transistor using pulse width modulation. Preferably, the input impedance is controlled to be low for low signal levels and to be high for high signal levels, which results in a more reliable sensing of binary signals. The device may be used for detecting the state of contact transducers suffering from parasitic resistances caused by moist and/or polluted environments. Further, a method of sensing a binary signal is provided.

Digital input with variable impedance

A method, device and computer program product for providing increased reliability in the processing of digital signals. The device includes a module for performing analog measurement of a received signal intended to occupy two logical states at various instances in time, a module for determining if there is a change in the analog signal level, a module for determining if the change fulfills at least one logical state change condition, wherein a first logical state change condition is based on the speed of change of the analog signal level, and a module for determining that there is a change from one logical state to the other if at least one logical state change condition is fulfilled. The invention provides secure detection of unreliable digital signals that may be generated in harsh environments that are polluted or moist.

Increased reliability in the processing of digital signals

A method for sending signals from an active computer in a high-voltage power transmission system including active protection computers and active and standby control computers in a hierarchical structure having at least two hierarchical levels. A high-voltage power transmission system and a control station for at least a part of such a transmission system. In the system all computers on the various hierarchical levels are connected to at least two separate computer communication networks. An active computer sends signals that are to be received by at least one other computer at the same or another hierarchical level simultaneously on the two separate computer communication networks to which it is connected.

Point-to-point communication in a high voltage power transmission system

Redundant computers and computer communication networks in a high-voltage power transmission system

A method and device for providing redundant control of a controllable current valve in a converter of a power transmission system. A first converter control unit sends a first valve control signal. A first active/standby indicator is associated with the first converter. A second converter control unit sends a second valve control signal. A second active/standby indicator is associated with the second converter control unit. The device also includes a valve control unit. An active/standby indicator indicates if a corresponding converter control unit is active or standby. Only one indicator indicates an active unit at a given point in time. The valve control unit receives the active/standby indicators and valve control signals, selects a valve control signal to be applied if the corresponding active/standby indicator indicates an active converter control unit and controls the current valve using the selected valve control signal.

Redundant current valve control in a high voltage power transmission system

A voltage measurement device for connection to a primary voltage dividing element provided between ground and an electrically conducting element in a system for controlling an electrical process and such a system. The device includes at least one first branch of secondary voltage dividing elements, where the branch is adapted to be connected in parallel with the primary voltage dividing element, and a first measuring unit connected to one of the secondary voltage dividing elements of the first branch and arranged to measure the voltage across this secondary voltage dividing element and provide a first voltage signal corresponding to a voltage of the electrically conducting element.

Voltage measurements of electrically conducting elements in systems for controlling electrical processes

A device in a valve on high voltage potential level and in a high voltage converter station comprises members arranged on high voltage level and adapted to detect parameters of a voltage divider circuit consisting of resistances (,) and capacitors (,) connected in series and across each thyristor of said valve. The capacitors are of self-healing type, in which from the point of time for occurring of a possible fault thereof the capacitance is gradually reduced, and said members are adapted to carry out measurements so as to determine whether the capacitance of the capacitors is changed over the time.

Device for supervising a high voltage converter station

A device for supervising the cooling of a cooling system of a valve of a high voltage converter station located on high voltage potential level comprises members (,) located on high voltage potential level and adapted to detect the temperature at cooling blocks (,) of the valve on high voltage potential level and send values so detected to first control units (,) for controlling semiconductor components (,) of the valve. The first control units have means (,) for treating said values detected and the first control units are adapted to send data resulting from said treatment to an arrangement (,) for supervising said valve located on low potential level.

HVDC power transmission system with cooling and switching device temperature detection

Device for supervising in a high voltage converter station

An apparatus and method for communication between low potential level and a valve of a high voltage converter station located on high voltage potential level is provided. The apparatus comprises means adapted to send serial messages on light conductors between a valve control unit and a first control unit for controlling semiconductor components of the valve of turn-on type on high voltage potential level in periods of time when the respective light conductor is free from signals associated with a change in the conducting state of the semiconductor component, such as turn-on and/or indications signals.

Method and a device for communication in a high voltage converter station

In a method for monitoring and/or control of a plant component (4A, 4B, 4C, 4D) connected to an electric power network (N1, N2), for example a tunable filter for harmonic filtering or a capacitor bank for generating reactive power in a converter plant for high-voltage direct current, products of, respectively, a voltage (U.sub.A, U.sub.B, U.sub.C, U.sub.D) occurring in the plant component and of a current (I.sub.A, I.sub.B, I.sub.C, I.sub.D, I.sub.AC) flowing therethrough are formed, and sine and cosine signals, the frequencies of which are equal to the product of the ordinal number of a selected tone and a fundamental frequency associated with the power network, the products are integrated and the phase difference (.phi..sub.un -.phi..sub.In) and/or the amplitude value (SUn, SIn, respectively) between/for the components of the voltage and the current of the selected tone are formed by quotient generation, multiplication, and summation of the integrated products.

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Smedjebacken, Sweden

Krister Nyberg