Abstract: A static compensator system for providing reactive and/or active power to a power network. The system includes a static compensator, which has a DC capacitor Ud and a voltage source converter. The static compensator is connected to an energy storage device. The system further includes a booster converter device connected in series with the energy storage device and in parallel with the DC capacitor Ud of the static compensator. The booster converter device and the energy storage device are further connected in parallel with the voltage source converter of the static compensator.

Abstract: An apparatus for reducing subsynchronous resonance phenomena in a power transmission system. A determining arrangement determines components of the voltage from stator windings of a generator with one or more discrete frequencies. A calculating arrangement calculates, on a basis of the result of the determining, a voltage to be added to the voltage from the stator windings for reducing phenomena in the power system and an arrangement adapted to add the voltage calculated to the voltage from the stator windings.

Abstract: A power supply apparatus includes a coupling capacitor arranged to be connected on its first end to ground; a transformer including a primary winding and a secondary winding; a first rectifier bridge connected in parallel with the secondary winding; and an energy storage, to which a load is arranged to be connected. The primary winding is arranged to be connected between a second end of the coupling capacitor and a high voltage transmission line such that all current between the second end of the coupling capacitor and the high voltage transmission line passes through the primary winding. The energy storage is arranged to be charged by means of a current passing through the first rectifier bridge. Furthermore, the power supply apparatus includes a bypasser. A corresponding three-phase apparatus is also presented.

Abstract: A one-phase static var compensator apparatus includes a compensator string consisting of a first static var compensator connected serially to a thyristor valve. The compensator string is arranged to be connected on its first end to one phase of a transmission grid of a rated voltage exceeding 69 kV. Moreover, the thyristor valve includes a plurality of thyristors connected serially and the compensator string is arranged to be directly connected to the transmission grid. A corresponding three phase apparatus is also presented.

Abstract: A temperature controller for providing heat to an energy storage device of a power compensator. The energy storage device includes a plurality of high temperature battery units on high potential. The temperature controller includes a pipe network for housing a heat transfer medium. The pipe network includes a main pipe loop and a local pipe loop in each battery unit. Each local pipe loop includes a first end for receiving a heat transfer medium and a second end for exhausting the medium.

Abstract: A power compensator for an electric power transmission line. The power compensator includes a voltage source converter, a capacitor and an energy storage device. The energy storage device includes a high voltage battery having a short circuit failure mode, a first main switch and second main switch for disconnecting the battery from the capacitor, and a control unit for operating the first and second switch.

Abstract: A charge controller of a high temperature battery for a power compensator of an electric power transmission line. The charge controller includes a sensor and a processor including a memory module. The charge controller includes a virtual battery model of the battery.

Abstract: An energy supply system adapted for supplying energy to equipment on a high voltage platform. The system includes a fuel cell and an effectuating capacitor. The system also includes an intermediate storage and supply unit. This unit stores energy from the fuel cell and supplies energy to the effectuating capacitor via an electric transforming unit. A high voltage platform including the energy supply system. An electrical network including the platform. A method for supplying energy to equipment on a high voltage platform.

Abstract: A method for controlling the power flow in an ac transmission line including prompt handling of voltage recovery and only thereafter thermal constraints.

Abstract: An auxiliary power supply equipment for a high voltage installation includes a power source at ground potential, a load circuit at high potential, and a transmission link for coupling the power source to the load circuit. The power source includes a high frequency voltage generator, and the transmission link comprises a first and a second current path. Each path is closed by capacitive coupling to provide insulation between the ground potential and the high potential, and each current path has a reactive compensation means for series compensation of reactive power generated by the capacitive coupling.

Abstract: An electric network for generation and transmission of electric power, including a power generating part, a point of common connection for the power generating part, a transmission link, a load network, and a reactive power compensator. The transmission link is coupled between the point of common connection and a grid connection point at the load network. The reactive power compensator is coupled to transmission link. The power generating part includes at least one wind turbine with an electric generator of induction type, coupled to the point of common connection. The reactive power compensator includes a capacitor bank and in parallel coupling to the capacitor bank a controllable inductor having a magnetic core, a main winding for alternating current, and a DC-control winding for direct current. The DC-control winding for control of the magnetic flux is set up by the main winding via orthogonal magnetization of the core.

Abstract: An electric network for generation and transmission of electric power, including a power generating part, a point of common connection for the power generating part, a transmission link, a load network, and a reactive power compensator. The transmission link is coupled between the point of common connection and a grid connection point at the load network. The reactive power compensator is coupled to transmission link. The power generating part includes at least one wind turbine with an electric generator of induction type, coupled to the point of common connection. The reactive power compensator includes a capacitor bank and in parallel coupling to the capacitor bank a controllable inductor having a magnetic core, a main winding for alternating current, and a DC-control winding for direct current. The DC-control winding for control of the magnetic flux is set up by the main winding via orthogonal magnetization of the core.

Abstract: An auxiliary power supply equipment for a high voltage installation includes a power source at ground potential, a load circuit at high potential, and a transmission link for coupling the power source to the load circuit. The power source includes a high frequency voltage generator, and the transmission link comprises a first and a second current path. Each path is closed by capacitive coupling to provide insulation between the ground potential and the high potential, and each current path has a reactive compensation means for series compensation of reactive power generated by the capacitive coupling.

Abstract: A device for control of a compensator connected to a polyphase electric transmission network for reactive electric power in dependence on a voltage sensed in the transmission network. A voltage controller, in dependence on the difference of a reference value for the voltage and its sensed value, forms a reference value for a reactive power flow through the compensator. A transformation element represents the sensed voltage as a voltage vector in a rotating two-phase system of coordinates and forms a compensation signal in dependence on a sensed change of the angular position of the voltage vector in the two-phase system of coordinates. A summation element forms the reference value for reactive power flow through the compensator in dependence on the compensation signal.

Abstract: A device for control of a compensator (SVC), connected to a polyphase electric transmission network (NW), for reactive electric power in dependence on a voltage (Vabc) sensed in the transmission network has a voltage controller (7, 8) which, in dependence on the difference of a reference value (V, ref) for said voltage and its sensed value, forms a reference value (QCR) for a reactive power flow (QC) through the compensator. The device comprises transformation means (3, 4, 11, 12, 13) which represents the sensed voltage as a voltage vector (Vdq) in a rotating two-phase system of coordinates and form a compensation signal (Sc) in dependence on a sensed change of the angular position of the voltage vector in the two-phase system of coordinates. The device further comprises summation means (9) for forming the reference value for reactive power flow through the compensator in dependence on the compensation signal.

Abstract: In a method for damping power oscillations in a transmission line, at least one first angular-frequency signal is generated, representing a first angular frequency which is given by a prior knowledge of oscillation frequencies expected in the power system, and a first phase-reference signal is formed as the time integral of the angular-frequency signal. A power quantity in the transmission line characterizing the power is sensed and a first estimated power quantity is formed, representing for an oscillation of the first angular frequency, its amplitude and phase position relative to the first phase-reference signal. A first damping signal is formed with an amplitude dependent on the amplitude of the first estimated power quantity and with a first phase shift in relation to the phase position thereof, and the first damping signal is supplied to an actuator for influencing the power transmitted in the transmission line.

Abstract: Thyristor-controlled series capacitor equipment (CEQ), intended for connection between an ac network (NET) and a converter (CONV), connected thereto, for conversion between alternating current ((IT) and high-voltage direct current (Id), with a controllable semiconductor valve (TYSW), has control equipment with control means (32) which, in dependence on a synchronization signal (&PHgr;SYNC), form firing pulses (TP1,TP2) for control of the semiconductor valve. The converter has a control device (CTR1) which forms a control-angle order (&agr;-ORD) for phase-angle control of the converter, related to the phase position for a voltage (U12) at a chosen connection point (J2).

Abstract: A device for compensation of the reactive power consumption of an industrial load, preferably an electric arc furnace or a plant for rolling of metallic materials, supplied from a three-phase (a, b, c) electric ac network, comprises a first compensation device for controllable consumption of reactive power and a second compensation device for generation of reactive power. The first compensation device comprises an inductor connected in series with a semiconductor connection controllable in dependence on a control order (.alpha.ref) supplied thereto. Control equipment is supplied with measured values of voltage (Ua, Ub, Uc) and current (Ia, Ib, Ic), respectively, at the load. The control equipment comprises devices for determination of the instantaneous consumption of active and reactive power by the load, and a control device which forms the control signal to the first compensation device in dependence on the consumption of reactive power and active power by the load.

Abstract: Control equipment (CE) for a series capacitor (1) connected into an electric power line (2) has a semiconductor valve (3), which is controllable in both directions, for connection in parallel with the capacitor. An inductor (4) is adapted to form, together with the capacitor, an oscillation circuit in which the semiconductor valve is included. The equipment has control members (PLL, TC) for firing the semiconductor valve for reversal of the capacitor charge and for control of the times (t.sub.p) for the zero crossings of the capacitor voltage (u.sub.C) such that these become substantially equidistant also in the presence of subsynchronous components in the power line current.

Abstract: An arc furnace (1) has an electrode (13) and connection members (14) for connection to a power-supply network (20) for supplying an arc (16) at the electrode with current. The furnace is provided with a voltage-pulse generating member (3) adapted, in connection with an interruption in the arc, to supply voltage pulses to the furnace for striking the arc.