Abstract: The present invention relates to an on-load tap changer control method for a power transformer in a power system. The power transformer has a primary side for a connection to a first grid in which electric power is generated, and a secondary side for connection to a second grid in which electrical power is consumed, the power transformer being equipped with an on-load tap changer. The method includes measuring the voltage and current at least on the primary side (u1, i1) or on the secondary side (u2 i2) of the power transformer, processing said measured voltages (u1; u2) and currents (i1; i2) in order to derive prospective reactive power at the output of the power transformer after prospective tap-change, comparing prospective reactive power to a predefined set-point, and—initiating tap-change of on-load tap changer if prospective reactive power is closer to said predefined set-point than actual reactive power.

Abstract: A power plant with a fossil fuel fired boiler, an air feed system, flue gas system and condensate system. A unitary flue gas heat exchanger spans a bypass line in the flue gas system and the condensate system so as to improve the thermal efficiency of the power plant while minimising complexity.

Abstract: This application relates to methods and apparatus for control apparatus of a voltage source converter for direct current transmission of electrical power over a transmission line. The control apparatus comprises regulation control for generating a regulation signal for the converter to regulate an electrical parameter of the voltage source converter, such as voltage or power, so as to regulate power transmission over the transmission line. The regulation signal is based on the difference between a measured value of said parameter and a reference value of said parameter, as may be supplied from a reference control block and may be derived from a demand signal indicating the voltage or power demand. The apparatus also includes damping control configured to generate a damping signal for modulating said regulation signal to reduce the effect of resonance within the bandwidth of control of the converter.

Abstract: Systems and methods according to these exemplary embodiments provide for methods and systems related to optical current sensors used to monitor standby power transformers, specifically fiber optical current and voltage sensors and, more particularly, to applications involving filters for use in such sensors, such as frequency tracking comb filters. According to one embodiment, a method for monitoring a connection condition of a stand by power transformer includes the steps of measuring a current flowing through a high voltage side of the standby power transformer using at least one optical current sensor disposed proximate to a current flow path of the high voltage side, using a comb filter to filter the measured current, determining whether the filtered, measured current is less than a predetermined threshold value; and generating an alarm indication that the high voltage side of the standby power transformer is unconnected.

Abstract: Device for making and/or breaking a current including a pair of permanent contacts (3, 4), at least one of the contacts (3, 4) being movable. At least one permanent contact (3, 4) including a main portion (3.1, 4.1) having a free end and an end protection portion (3.2, 4.2) secured to the free end of the main portion (3.1, 4.1), designed to be in mechanical and electrical contact with the other permanent contact (4, 3) only during an operation for opening or closing the pair. The end protection portion (3.2, 4.2) is made of a single transition metal having a melting temperature that is strictly higher than that of the main portion (3.1, 4.1) to which it is secured, or of an oxide or carbide of such a metal, or even of zinc oxide. For application in particular to high- or medium-voltage circuit breakers.

Abstract: A device for regulating the supply to a photovoltaic converter, the device comprising: a laser source (2); a photovoltaic converter (6) that feeds a DC-DC converter (8); circuit (100) for regulating the input impedance of said DC-DC converter (8) as a function of the operating voltage (Us) of the photovoltaic converter (6) and of its no-load voltage (Us0); and circuit (42) for measuring an output voltage of the DC-DC converter (8) and for producing a regulation signal (SR) for regulating the laser source.

Abstract: Circuits comprising at least one energy storage device, a resistor and switch arranged in series with the resistor are described. The energy storage device is arranged in parallel with the series connection of the switch and the resistor, and the switch is arranged to selectively switch the resistor into a parallel connection to the energy storage device. In some examples, the switch comprises a series connection of semiconductor switching elements. In some examples, the circuit may comprise a sub-module for use in a multilevel modular converter.

Abstract: This application relates to control methods and apparatus for a voltage source converter comprising a plurality of energy storage devices which can be selectively connected into an arm of the voltage source converter. The apparatus is configured to generate a modelled value of the voltage of an energy storage device of the voltage source converter based on one or more model parameters and the operation of the voltage source converter, receive the modelled value and also a measured value of the voltage of at least one energy storage device, determine an error between the modelled value and the measured value, and generate a model control signal for adapting the model based on said error so that the modelled value substantially corresponds to the measured value. Control circuitry is responsive to said model module and/or said model adaptation module to control operation of the voltage source converter.

Abstract: A high- or medium-voltage circuit breaker, in which a movable contact (1) is moved in sliding in order to separate stationary contacts (11, 12) from its sliding surface (2). In accordance with the invention, the stationary contacts (11, 12) have switching portions (9) that separate from the movable contact more or less simultaneously as a result of a setback (19) in the movable contact (1), thereby causing two simultaneous switching arcs to appear (14, 15), which arcs are extinguished much more quickly than a single arc, before the current is transferred to the conventional arcing contacts (5). This disposition enables the stationary contacts (11, 12) and their environment to be less exposed to damage.

Abstract: A DC to DC converter for converting voltage between two voltage levels is described. The converter comprises a plurality of capacitors and switch units and is controllable between a first and second commutation state. In the first commutation state, the converter is configured for connection to higher voltage terminals and the capacitors are connected in series. In the second commutation state, the converter is configured for connection to lower voltage terminals, and the capacitors are connected to form at least two branches connected in parallel, the branches comprising a series connection of at least two capacitors. In some embodiments, one or more intermediate commutation states may also be provided.

Abstract: A solar thermal power system includes a solar receiver, and a thermal energy storage arrangement having thermal energy storage fluid to be circulated through the solar receiver to store thermal energy. The system includes a multistage steam turbine operable on variable pressure steam generated by a steam generator arrangement, by utilizing the thermal energy storage fluid. The arrangement includes an economizer section, an evaporator section, and a superheater section communicably configured to utilize the heat of the hot thermal energy storage fluid to generate and supply the variable pressure steam to the turbine. The system includes a recirculation line configured around the economizer section to recirculate the heated water to an inlet of the economizer section, increasing pressure range of the variable pressure steam in the arrangement.

Abstract: The invention relates to a circuit breaker (10) for an electricity transport installation, the circuit breaker comprising a tank (12), a vacuum bottle (20) that has a stationary contact (24), a movable contact (26), and sealing means (40), a casing (30) that is arranged inside the tank (12), that electrically connects the movable contact (26) to an electrical conductor (18), and that co-operates with an outside wall of the vacuum bottle (20) to define a volume (42) that is taken to a pressure close to atmospheric pressure, and feeder means for feeding the inside volume (42) of the casing (30), which feeder means pass through the inside volume (14) of the tank (12), the circuit breaker being characterized in that the feeder means for feeding the inside volume (42) of the casing (30) consist in a tubular element (38, 54, 56) made of insulating material.

Abstract: The invention relates to a conductor (2) for electrical equipment, the conductor comprising at least one hollow section member (2) of electrically conductive material that is elongate along a longitudinal axis (Y), the conductor having an outside surface in which at least a portion forms corrugations (23, 24) in a plane perpendicular to the longitudinal axis. The conductor may advantageously form a movable contact (blade) (2) of a high voltage disconnector.

Abstract: A disconnector for high voltage, including columnar supporting elements which are electrically isolating and are adapted to support electromechanical elements of opening and closing a circuit or an electrical line. At least one columnar supporting element, which is tubular, supports an optical current transformer, the optical fiber of which, surrounded by protection elements, extends inside the tubular columnar supporting element.

Abstract: The invention provides a RC module (20) for a RC voltage divider for an electrical substation insulated by a dielectric fluid. The RC module (20) comprises first and second plane conductive supports (210a,b) separated from each other in order to co-operate with the dielectric fluid to form a capacitor, when the module equips an electrical substation. The module further comprises at least one resistive element (220a,b) electrically connecting together the first and the second conductive supports (210a,b), the resistive element comprising a printed circuit (222) defining a resistive electric circuit including a plurality of resistive 2-terminal components mounted in series. The invention also provides a resistive element and a voltage divider.

Abstract: The present invention relates to medium- or high-voltage equipment having low environmental impact, including a leaktight enclosure in which there are located electrical components covered with a solid dielectric layer of varying thickness and a gaseous medium for providing electrical insulation and/or for extinguishing electric arcs that are likely to occur in said enclosure, and that comprises heptafluoroisobutyronitrile in a mixture with a dilution gas.

Abstract: The invention provides a support structure (10) comprising at least one cylindrical pillar (16) of vertical main axis, having a bottom end (16i) that is connected to the ground (14) and a top end (16s) connected to a component to be supported; the support structure being characterized in that the pillar (16) includes at least one helical slot (20) coaxial about the main axis of the pillar (16).

Abstract: The invention relates to an assembly of modules for an electrical circuit comprising: a module support for at least two modules and at least two modules, each module comprising two complementary connectable sub-modules. The module support comprises for each sub-module at least an alignment member adapted to individually align the sub-module during its installation on the module support in such way to connect it to complementary sub-module already installed on the module support to form one of the modules. The invention also relates on a module support, a module and a Flexible Alternative Current Transmission Systems.

Abstract: The present invention provides medium- or high-voltage equipment including a leaktight enclosure in which there are located electrical components and a gas mixture for providing electrical insulation and/or for extinguishing electric arcs that are likely to occur in said enclosure, the gas mixture comprising heptafluoroisobutyronitrile, carbon dioxide, and oxygen in small quantities. Electrical components covered in a solid dielectric layer of varying thickness are located inside said leaktight enclosure of the equipment of the invention.

Abstract: A configuration for joining a ceramic layer has a thermal insulating material to a metallic layer. The configuration includes an interface layer made of metallic material located between the ceramic layer and the metallic layer, which includes a plurality of interlocking elements on one of its sides, facing the ceramic layer, the ceramic layer comprising a plurality of cavities aimed at connecting with the corresponding interlocking elements of the interface layer. The configuration also includes a brazing layer by means of which the interface layer is joint to the metallic layer. The invention also refers to a method for obtaining such a configuration.