Connection arrangement for the stator winding of a turbo machine having two or more parallel circuits

In a connection arrangement (10) for the stator winding of a turbo machine with two or more parallel circuits of individual conductors (26, 29) per phase, the individual conductors belonging to one phase form a phase group (25, 28) and run directly adjacent to one another in the stator body, the individual conductors of the winding are each connected from a winding connection (21, . . . , 24) to an external connection (15, . . . , 20) via a phase ring (32), which runs concentrically with respect to the machine axis (33).A simplification of the manufacture and assembly as well as a reduction in space requirements and an improvement in the thermal properties are achieved by the phase rings (32) of a phase group each being led together as a phase ring group (11, . . . , 14) from the winding connections (21, . . . , 24) to the external connections (15, . . . , 20).

This application claims priority under 35 U.S.C. § 119 to Swiss application number 00110/06, filed 24 Jan. 2006, the entirety of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of electrical machines. It relates to a connection arrangement for the stator winding of a turbo machine with two or more parallel circuits.

2. Brief Description of the Related Art

There are numerous schemes in which the connections are led from the stator winding of an electrical machine to the machine or generator housing in order to be connected there to the busbars. In general, the connecting conductors are in this case led from the phase connection location, i.e., from the ends of the winding bars protruding out of the slots of the stator body, along the rear side of the evolute of the stator end winding up to external connections arranged on a circumferential circle.

The arrangement used depends on the winding scheme, in particular on the number of phases, the number of poles and the number of circuits per phase. In general, the various phase connecting conductors are arranged such that the sum of the currents of all phase rings at any desired circumferential location is limited to a specific value in order to avoid imbalances in the magnetomotive force (MMF) resulting from the currents in the phase rings. In general, such connecting rings (phase rings) are insulated individually and laid individually according to the physical and electrical boundary conditions.

The article by Nagano S, Kitajima T, Yoshida K, Kazao Y, Murata D, Nagakura K., “Development of world's largest hydrogen-cooled turbine generator”, PES Summer Meeting July 2002, Proceedings volume 2, pages 657-663 describes the construction and testing of a hydrogen-cooled 500-600 MVA generator.FIG. 15(b) therein illustrates the phase ring connections and shows that the winding has three phases, of which each has three parallel circuits, all six external connections being arranged on the base of the machine. The three parallel circuits are arranged such that they run together in adjacent stator slots within a phase group. However, the phase rings which connect them to the external connections are insulated individually and led individually to a suitable external connection.

The article by R. Lari and V. Tartaglione, “THR-L63, An Advanced Generator coupled front and back to gas and steam turbine for single shaft configuration”, PowerGen Europe, Dusseldorf 6-8 May 2003, describes the construction of a hydrogen-cooled 400 MW generator. The diagram shown therein on page 11 of the end winding supports shows that the winding likewise has three phases, which each have three parallel circuits, and three external connections on the base and three external connections on the upper side of the machine. The three parallel circuits are arranged such that they run together in adjacent slots of the stator within a phase group. However, here too, the phase rings which they connect to the external connections are insulated individually and led individually to a suitable external connection.

The known technique of individually leading the phase ring connections means that each ring needs to be insulated from the full voltage between two phases and mounted and installed individually. This results in impaired thermal properties of the connecting conductors and an increased space requirement owing to the thicker bar insulation and/or owing to the increased distance between the bars. Also, the need to manufacture and install individual bars results in the manufacture and assembly of the winding being time-consuming and expensive. This is particularly the case when each phase has more than two parallel circuits.

SUMMARY OF THE INVENTION

One of numerous aspects of the present invention includes providing a connection arrangement for the stator winding of a turbo machine with two or more parallel circuits, which is characterized by reduced manufacturing and assembly complexity and requires less space in the machine.

Another advantageous aspect of the present invention includes that the phase rings of a phase group within the connection arrangement are each led systematically together as a phase ring group from the winding connections to the external connections. This avoids a situation in which all of the phase rings need to be designed individually in terms of the insulation for the maximum voltage between two phases with the negative consequences outlined above.

One exemplary configuration in accordance with the present invention includes individual conductors of a phase group run separately from one another in adjacent slots of the stator body.

Another exemplary configuration in accordance with the present invention includes individual conductors of a phase group being assembled in a manner in which they are insulated from one another, to form a unit provided with common outer insulation.

In particular, the individual conductors for their part may include individual conductor elements.

Yet another exemplary configuration in accordance with the present invention includes adjacent phase rings of two adjacent phase ring groups having a first distance from one another, the phase rings of a phase ring group having a second distance from one another, and the second distance is markedly smaller than the first distance.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1reproduces a perspective illustration of an exemplary embodiment of a connection arrangement according to the invention. The stator itself, the stator winding, and the machine housing are not illustrated for reasons of clarity. The connection arrangement10is designed for three phases, which each have three parallel circuits. The external connections15,16,17and18,19,20, which are arranged on the upper side of the machine, belong to the three phases. The winding, which is led parallel to the machine axis33through the stator body34in the stator slots35, is connected to the connection arrangement10at a large number of winding connections. Of the winding connections, only the winding connections of one phase are provided with the reference symbols21, . . . ,24, in a representative manner. In the example inFIG. 1, in each case three parallel winding circuits are provided per phase, whose (three) individual conductors26—as shown in FIG.2—run next to one another in phase groups25and are accommodated in adjacent stator slots35. Accordingly, in each case three adjacent connections are provided at the winding connections21, . . . ,24inFIG. 1. Each of the individual conductors26is connected in the winding connections21, . . . ,24to the associated external connection15, . . . ,20by means of a phase ring32, which is arranged concentrically with respect to the machine axis33.

An advantageous aspect of the invention includes the systematic (ordered) leading of these phase rings32, which are associated with a certain phase, together as a phase ring group11, . . . ,14from the winding connections21, . . . ,24to the external connections15, . . . ,20, as is shown inFIG. 1. This results in a plurality of phase ring groups11, . . . ,14each with three parallel phase rings32with corresponding individual conductors26. This arrangement means that adjacent phase rings32of two adjacent phase ring groups11, . . . ,14, as shown inFIG. 2, have a first distance d2from one another, that the phase rings32of a phase ring group11, . . . ,14have a second distance d1from one another, and that the second distance dl may be selected to be markedly smaller than the first distance d2owing to the lower requirements placed on the dielectric strength. This also means that the insulation thickness of the conductor insulation (27inFIG. 2) of each individual conductor (bar)26within the phase group25or phase ring group11can be reduced, as a result of which the thermal properties are improved and the manufacturing costs are reduced and, at the same time, a more compact arrangement of the conductors is made possible. An additional advantage is that the phase rings32can be manufactured and assembled in phase groups25, as a result of which the time for the in-plant assembly and subsequent packaging and fixing can be markedly reduced.

FIG. 1shows the proposed phase ring arrangement for a phase connection with three phases, three parallel circuits per phase, and with the external connections15, . . . ,20on the upper side (or on the base) of the machine. The three individual conductors26are led systematically together as a group from the stator winding to the external connection. Similar arrangements are possible for any desired locations of the external connections, for example with three connections at the top and three connections at the bottom. The individual conductors can in this case either have a solid Cu cross section (FIG. 2) or themselves include a plurality of individual conductor elements, which can be transposed (Roebel bar) in order to reduce circulating current losses (FIG. 3). In addition, the individual conductors within a phase group28can be manufactured as a complete unit, an intermediate insulation30being provided between the individual conductors29and an outer insulation31being provided around the conductor group (FIG. 3).

Principles of the present invention can be applied to any desired stator windings with two or more circuits, whose windings are accommodated in adjacent slots, and can be applied to phase sequences which rotate in the same direction as or in the opposite direction to the direction of rotation of the rotor.