Abstract:
The present disclosure relates to the technical field of conductor bars, especially for assembly into electric machines. It is an object of the invention to provide an alternative method for fabricating a conductor bar with a vacuum pressure resin-rich process. Described is a method for producing a conductor bar comprising the steps of packing a conductive bar with a B-stage resin-rich main wall insulation into a layer of release tape, a layer of breather/ bleeder and thereon a layer of synthetic material which is forming a hermetical sealing around the pre-impregnated insulated conductive bar, placing the pre-impregnated insulated conductive bar with the layers described above into a vessel where the volume inside the synthetic layer is connected to a vacuum pump outside of the vessel and is evacuated while an overpressure is created inside the vessel with a heated compression gas causing a compacting and thermal curing of the resin-rich insulation around the conductive bar.
Abstract:
This application describes a voltage source converter (300) of the controlled transition bridge type, having three phase limbs, each phase limb having a high side director switch (S w1 , S w3 , S w5 ) and a low side director switch (S W4 , S W6 , S W2 ) connecting a respective DC terminal (DC+, DC-) to an AC node (102a-c) for that phase limb. Chain- link circuits (101a-c) for each phase limb comprise a plurality of series connect cells (103), each cell having an energy storage element (105) that can be selectively connected in series or bypassed. The chain-link circuits are operated in a voltage mode to provide a defined voltage transition at the AC node during a transition between one director switch being turned off and the other directors switch being turned on. In embodiments of the invention the chain-link circuits (101a-c) are connected to a common node such that, in use, a current can flow from one phase limb to another via the respective chain-link circuits. A converter controller (900) operates a chain-link circuit of a phase limb in a current mode to provide a defined chain-link current for at least part of the time when that phase limb is not in a transition state. The defined current can allow correct circulation of the DC current and/or provide capacitor balancing of the capacitors of a chain-link circuit. Additional chain-link circuits (301, 302) are provided between the DC terminals and the common node to provide a DC current in a converter state where all the high side or low side director switches are off at the same time.
Abstract:
A voltage source converter (30) comprises first and second DC terminals (32,34) for connection to a DC network (58). The voltage source converter (30) further includes at least one limb connected between the first and second DC terminals (32,34). The or each limb includes: a phase element (36) including two parallel-connected sets of series-connected switching elements (40) connected in an H-bridge to define first and second diagonal switching pairs, a respective junction between each set of series-connected switching elements (36) defining an AC terminal (40) for connection to an AC network (50); and a sub-converter (38,39) configured to be controllable to act as a voltage waveform synthesiser; wherein the voltage source converter (30) further includes a controller (60) to operate the sub-converter (38,39) to selectively synthesise a driving commutation voltage to modify a DC side current at a DC side of the H-bridge so as to minimise any differences in magnitude and direction between the DC side current and an AC side current at an AC side of the H-bridge and thereby carry out commutation of current from one of the first and second diagonal switching pairs to the other of the first and second diagonal switching pairs.
Abstract:
Circuits comprising at least one energy storage device (120), a resistor (206) and switch (204) arranged in series with the resistor (206) are described. The energy storage device is arranged in parallel with the series connection of the switch (204) and the resistor (206), and the switch (204) is arranged to selectively switch the resistor (206) into a parallel connection to the energy storage device (120). In some examples, the switch (204) comprises a series connection of semiconductor switching elements (202). In some examples, the circuit may comprise a sub-module (200) for use in a multilevel modular converter (300).
Abstract:
The invention refers to a method for controlling part load operation of a gas turbine comprising a controller (27) wherein a load set point (LSP) of the controller (27) is greater or equal a minimum load set point (LSPmin).The minimum load set point (LSPmin) depends on a hot gas temperature (THG) that is calculated based on a hot gas temperature model (57).
Abstract:
A voltage source converter (30), for interconnecting first and second electrical networks (44, 46), comprising: first and second terminals (32, 34) for connection to the first electrical network (44); and a primary converter limb (36a) extending between the first and second terminals (32, 34), the primary converter limb (36a) including first and second primary limb portions (38, 40) separated by a third terminal (42), the third terminal (42) being connectable to the second electrical network (46), each primary limb portion (38, 40) including at least one switching element (50) and/or a first chain-link converter, each primary limb portion (38, 40) being operable to be switched into and out of circuit between the third terminal (42) and a respective one of the first and second terminals (32, 34), each primary limb portion (38, 40) being operable to transfer power between the third terminal (42) and a respective one of the first and second terminals (32, 34); at least one second chain-link converter (58) connected to the third terminal (42), the or each chain-link converter (58) comprising a plurality of chain-link modules (60), each of the plurality of chain-link modules (60) being operable to selectively provide a voltage source, wherein the or each chain-link converter (58) includes a control unit configured to selectively operate the plurality of chain-link modules (60) to generate a discontinuous pulse width modulation voltage waveform; and a controller (62) configured to selectively operate the or each chain-link converter (58) to control the configuration of a discontinuous pulse width modulation voltage waveform at the third terminal (42), the controller (62) including the or each control unit, the controller (62) being configured to selectively control switching of each primary limb portion (38, 40) into circuit between the third terminal (42) and a respective one of the first and second terminals (32, 34) during a respective unmodulated period of the discontinuous pulse width modulation voltage waveform, the controller (62) being configured to selectively coordinate operation of the primary limb portions (38, 40) and the or each second chain-link converter (58) to control the configuration of the discontinuous pulse width modulation voltage waveform at the third terminal (42).
Abstract:
The invention relates to a combined cycle system, which comprises a gas turbine, a steam turbine and a heat recovery steam generator, wherein the steam discharged from the water separation unit is routed through a high pressure outlet line to the set of super-heaters and discharged from the set of super-heaters through a main outlet line of the heat recovery steam generator to be introduced into the steam turbine, an attemperating line is connected between the high pressure outlet line and the main outlet line of the heat recovery steam generator to introduce a portion of steam that is discharged from the water separation unit into the steam discharged from the set of super-heaters, and that a control valve is disposed in the attemperating line. With the solution of the present invention, pressure difference across control valve for steam temperature remains low in low load or high load application of the combined cycle system.
Abstract:
Method for manufacturing a braze joint gap for connecting a first part to a second part via brazing or soldering, comprising the steps of: adding microstructural elements to a first connecting surface of the first part to be connected to the second part via brazing or soldering; aligning the second part and the first part or an electrode part having a tool contour, which is identical to the contour of the first connecting surface; electro-chemically machining (ECM) or precise electro-chemically machining (PECM) a second connecting surface of the second part by polarizing the first part or the electrode part as a cathode and the second part as an anode.
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:
Aerating system (100) for the runner (10) of a hydraulic turbine, the runner (10) comprising a plurality of blades (2), such that inter-blade canals (11) are configured between each pair of blades (2) for the admission of air in the water flow circulating through the hydraulic turbine, such that the aerating system (100) comprises at least one hydrofoil (12) located in the inter-blade canal (11) of the runner (10) contacting the pair of blades (2) configuring the inter-blade canal (11) where the hydrofoil (12) is located, such that the hydrofoil (12) has a non-axis symmetrical profile, and such that at least one of the blades (2) in contact with the hydrofoil (12) comprises an aerating canal (20) delivering air to the hydrofoil (12).