Abstract:
An electric high voltage AC machine intended to be directly connected to a distribution or transmission network (16) comprises at least one winding. This winding comprises at least one current-carrying conductor, a first layer having semiconducting properties provided around said conductor, a solid insulating layer provided around said first layer, and a second layer having semiconducting properties provided around said insulating layer. In addition grounding means (18, 24, 26, 28) are provided to connect at least one point of said winding to ground.
Abstract:
The magnetic circuit of synchronous compensator plant is included in an electric machine which is directly connected to a high supply voltage of 20-800 kV, preferably higher than 36 kV. The electric machine is provided with solid insulation and its winding(s) is/are built up of a cable (6) intended for high voltage comprising one or more current-carrying conductors (31) with a number of strands (36) surrounded by at least one outer and one inner semiconducting layer (34, 32) and intermediate insulating layers (33). The outer semiconducting layer (34) is at earth potential. The phases of the winding are Y-connected, and the Y-point may be insulated and protected from over-voltage by means of surge arresters, or else the Y-point is earthed via a suppression filter. A procedure is used in the manufacture of a synchronous compensator for such plant, in which the cable used is threaded into the openings in the core for the magnetic circuit of the synchronous compensator.
Abstract:
A current-limitation system for limiting a current through an DC connection in case of a fault occurring in a DC grid of which the DC connection forms a part is provided, as well as a method of operating a current-limitation system for limiting a current through an DC connection in case of a fault occurring in a DC grid of which the DC connection forms a part.
Abstract:
A current-limitation system for limiting a current through an DC connection in case of a fault occurring in a DC grid of which the DC connection forms a part is provided, as well as a method of operating a current-limitation system for limiting a current through an DC connection in case of a fault occurring in a DC grid of which the DC connection forms a part.
Abstract:
The invention provides improved control of a power transmission system having a first group of measurement units (10, 12, 14) in a first geographical area (A_1) providing a first set of phasors and a second group of measurement units (16, 18) in a second geographical area (A_2) providing a second set of phasors, where the phasors in the sets are generated at the same instant in time. In this system the power control device (32) includes a phasor aligning unit (30) that time aligns the first and second sets of phasors and a control unit (33) that compares each set of phasors with a corresponding phasor number threshold, determines that a first control condition is fulfilled if each phasor number threshold has been exceeded and enables the provision of a common signal if the first control condition is fulfilled. The common signal is based on the obtained phasors in the first and second sets.
Abstract:
The present invention is concerned with the computation of power system sensitivities from power flow parameters and control parameters of a Power Flow Control Device (PFC). To this end, control parameter variations are applied to or generated by a PFC (20), and comprise variations in a control input u, a control effort e (injected series voltage, inserted series reactance), or a control effect q (power flow, active power transfer, phase-shift, current). A power flow response measuring unit (40) measures a variation of a power flow response such as current, active or apparent power, in a way sufficiently synchronized with the control parameter variation to allow establishing an unambiguous causal relationship or correspondence in the form of a power system sensitivity. The latter may be on-line adapted to continuously reflect an updated aspect of the power system behaviour, and thus enable an improved, fast and reliable power flow control in power systems comprising a meshed power network with two parallel flow paths or corridors connecting two areas or sub-systems.
Abstract:
A device (1) for control of power flow in a three-phase ac transmission line comprises a series transformer unit (10), a shunt transformer unit (20), and a reactance unit (30).
Abstract:
An electric high voltage AC machine intended to be directly connected to a distribution or transmission network (16) comprises at least one winding. This winding comprises at least one current-carrying conductor, a first layer having semiconducting properties provided around said conductor, a solid insulating layer provided around said first layer, and a second layer having semiconducting properties provided around said insulating layer. In addition grounding means (18, 24, 26, 28) are provided to connect at least one point of said winding to ground.
Abstract:
In a plant containing a turbo-generator the magnetic circuit of the turbo-generator is included in an electric generator which directly supplies a high supply voltage of 20-800 kV, preferably higher than 36 kV. The insulation of the generator is built up of a cable (6) comprising one or more current-carrying conductors (31) with a number of strands (36) surrounded by outer and inner semiconducting layers (34, 32) and intermediate insulating layers (33). The outer semiconducting layer (34) is at earth potential. The phases of the winding are Y-connected. The Y-point may be insulated and protected from over-voltage by means of surge arresters, or else the Y-point may be earthed via a suppression filter.
Abstract:
A DC grid (100) comprising a plurality of AC/DC converters (105) which are interconnected via DC lines (115) is provided, wherein, in order to limit the effects of a fault in the DC grid, the DC grid is divided into at least two zones (200) by means of at least one current limiter (205) in a manner so that a current limiter is connected in each of the DC line(s) (115z) by which two zones are interconnected. A method of limiting the effects of a fault in a DC grid by dividing the DC grid into at least two zones is also provided.