DE1065930B

DE1065930B -

Info

Publication number: DE1065930B
Application number: DENDAT1065930D
Authority: DE
Publication date: 1959-09-24

Description

Die Erfindung betrifft eine Anordnung zur Erleichterung des Parallelbetriebes von selbsterregten Synchrongeneratoren.The invention relates to an arrangement for facilitating the parallel operation of self-excited Synchronous generators.

Es ist üblich geworden, zumindest kleinere Synchrongeneratoren mit Selbsterregung auszuführen. Die Feldwicklung des Generators wird dabei gewöhnlich von einem Mehrphasengleichrichter und dieser von zwei parallel arbeitenden Gruppen von Stromtransformatoren gespeist, von denen die eine Gruppe von dem Belastungsstrom des Generators und die andere Gruppe von einem Strom beeinflußt wird, der proportional der abgegebenen Generatorspannung ist. ' Die eine Gruppe von Stromtransformatoren liefert also die Leerlauf erregung des Generators, während die andere Gruppe die Feldwicklung mit dem erforderlichen Kompoundstrom speist. Wenn dabei die Erregereinrichtung so angeordnet ist, daß der der abegebenen Generatorspannung proportionale Strom egenüber der Generatorspannung um 90° phasenverschoben ist, wird die Erregung die Einwirkung der Ankerrückwirkung ausgleichen, so daß die abgegebene Spannung annähernd unabhängig von der Größe und dem Phasenwinkel der Belastung wird. Beim Parallelbetrieb von solchen selbstregelnden Generatoren macht es indessen Schwierigkeiten, die Belastung auf die einzelnen Generatoren gleichmäßig zu verteilen. Die Verteilung der Wirkbelastung ist gewöhnlich durch Regulierung der Antriebsmomente der einzelnen Generatoren leicht einzustellen. Eine ähnliche Verteilung der Blindbelastung ist indessen nicht ohne weiteres erreichbar, da die Blindbelastung jedes Generators hauptsächlich von der Erregung des Generators bestimmt wird und die Grunderregungseinrichtungen der einzelnen Generatoren unabhängig voneinander sind.It has become customary to design at least smaller synchronous generators with self-excitation. The field winding of the generator is usually from a polyphase rectifier and this fed by two groups of current transformers working in parallel, one group of which is influenced by the load current of the generator and the other group is influenced by a current which is proportional to the generated generator voltage. 'Which supplies a group of current transformers so the no-load excitation of the generator, while the other group the field winding with the required Feeds compound current. If the excitation device is arranged so that the delivered Generator voltage proportional current phase shifted by 90 ° compared to the generator voltage is, the excitation will compensate for the action of the anchor reaction, so that the delivered Voltage is almost independent of the size and the phase angle of the load. With parallel operation of such self-regulating generators, however, makes it difficult to reduce the load on the evenly distribute the individual generators. The distribution of the active load is usually through Adjustment of the drive torques of the individual generators is easy. A similar distribution the blind load cannot, however, be reached without further ado, since the blind load is every Generator is mainly determined by the excitation of the generator and the basic excitation devices of the individual generators are independent of each other.

Um diesen Schwierigkeiten zu begegnen, ist es bereits bekannt, bei Parallelbetrieb von Synchronmaschinen der angegebenen Art die Erregerklemmen der Generatoren miteinander zu verbinden. Eine solche Parallelschaltung setzt aber gleiche Erregerspannungen und gleiche Erregerströme, d. h. gleiche Maschinen mit gleichen Erregerkennlinienverlauf, voraus. Das gilt im übrigen auch dann, wenn statt der genannten Klemmen Punkte gleichen, aber von der Netzspannung abweichenden Potentials miteinander verbunden werden. In diesem Fall wirken sich Unterschiede in der Erregerspannung nicht unmittelbar auf die Parallelschaltung aus. Um eine gleichmäßige Verteilung der Blindleistung mit der vorbeschriebenen Schaltung auch bei Maschinen mit verschiedenen Kennlinien zu erreichen, ist es weiter bekannt, die Primärseite der für die Erregung vorgesehene Gleichrichteranordnung über einen einstellbaren Ausgleichtransformator parallel zu schalten.In order to counter these difficulties, it is already known when synchronous machines are operated in parallel to connect the excitation terminals of the generators with one another in the specified manner. One however, such parallel connection sets the same excitation voltages and the same excitation currents, i. H. same Machines with the same excitation characteristic curve ahead. Incidentally, this also applies if instead of of the named terminals points are the same, but with potential deviating from the mains voltage get connected. In this case, differences in the excitation voltage do not have an immediate effect on the parallel connection. In order to achieve an even distribution of the reactive power with the previously described It is further to achieve switching even with machines with different characteristics known, the primary side of the rectifier arrangement provided for the excitation via an adjustable Connect equalizing transformer in parallel.

Anordnung zum Parallelbetrieb von selbsterregten SynchrongeneratorenArrangement for parallel operation of self-excited synchronous generators

Anmelder: Allmänna Svenska Elektriska Aktiebolaget, Västeräs (Schweden)Applicant: Allmänna Svenska Elektriska Aktiebolaget, Västeräs (Sweden)

Vertreter: Dipl.-Ing. H. Missling, Patentanwalt, Gießen, Bismarckstr. 43Representative: Dipl.-Ing. H. Missling, patent attorney, Giessen, Bismarckstrasse. 43

Beanspruchte Priorität: Schweden vom 26. April 1956Claimed priority: Sweden from April 26, 1956

Sven Eric Hedström, Melbourne (Australien), und Arne Sohlström, Västeräs (Schweden), sind als Erfinder genannt wordenSven Eric Hedström, Melbourne (Australia), and Arne Sohlström, Västeräs (Sweden), have been named as inventors

Das hat aber den Nachteil, daß das Verhältnis zwischen der Erregung der parallel arbeitenden Generatoren innerhalb des ganzen Arbeitsbereiches konstant bleibt, während das Verhältnis zwischen den Erregerströmen bei ungleichen Erregerkennlinien der Generatoren sich zwischen Leerlauf und Vollast ändert. Es wäre also notwendig, das Ubersetzungsverhältnis des Ausgleichstransformators bei Belastungsänderungen automatisch zu ändern. Eine derartige Regeleinrichtung würde aber eine bedeutende Verteuerung der Erregereinrichtung bedeuten.But this has the disadvantage that the relationship between the excitation of the parallel working Generators within the entire working area remains constant, while the ratio between the Excitation currents with unequal excitation characteristics of the generators vary between idle and full load changes. It would therefore be necessary to automatically change the transmission ratio of the compensation transformer when the load changes. Such a one Control device would mean a significant increase in the cost of the excitation device.

Die Mängel der bekannten Anordnungen vermeidet die Erfindung. Sie ist dadurch gekennzeichnet, daß jeder vom Belastungsstrom beeinflußte Stromwandler außer der die Erregerwicklung speisenden Sekundärwicklung noch eine zusätzliche Sekundärwicklung aufweist, welche mit entsprechenden zusätzlichen Sekundärwicklungen auf den entsprechenden Stromwandlern der anderen parallel arbeitenden Generatoren parallel geschaltet ist. Bei dieser Anordnung können den einzelnen Generatoren ungleich große belastungsstromabhängige Erregerkomponenten in der Weise zugeführt werden, daß die Windungszahlübersetzung zwischen der parallel geschalteten Sekundärwicklung und der die Erregerkomponente liefernden Sekundärwicklung ungleich groß in den einzelnen Generatoren bemessen wird. Es wird so der Parallelbetrieb vonThe invention avoids the shortcomings of the known arrangements. It is characterized in that every current transformer influenced by the load current except the secondary winding feeding the excitation winding still has an additional secondary winding, which with corresponding additional Secondary windings on the corresponding current transformers of the other generators working in parallel is connected in parallel. With this arrangement, the individual generators can vary in size depending on the load current Excitation components are supplied in such a way that the number of turns translation between the secondary winding connected in parallel and the secondary winding supplying the excitation component is dimensioned unequal in size in the individual generators. The parallel operation of

909 629/115909 629/115

Claims

Self-regulating synchronous generators of different sizes are possible, with the reactive load being distributed to the individual generators according to their size. The. Winding ratio between the secondary winding supplying the excitation component and the secondary winding connected in parallel for each generator size within a series of generators of unequal size selected so that any generators can be operated in parallel by simply connecting their current transformers in parallel. In the drawing, the invention is explained for two self-excited synchronous generators operating in parallel. 1 denotes a common three-phase network on which two synchronous generators 2a and 2b work in parallel via a switch 3a and 3b each. The field windings 4 a and 4 b of the generators are fed by three-phase rectifiers 5 a and 5 b, which are connected ao to two groups of current transformers 60 and 7a or 6 b and 7 b operating in parallel. One of these groups (6) is influenced by the load current of the generator, the other group (7) by a current which is proportional to the generated generator voltage. The inductive or capacitive loads 80 and 8 b ensure that the currents that influence the current transformer groups 7 a and 7 b are phase-shifted by 90 ° with respect to the voltages output by the generators. This device makes the generators self-regulating in the normal case, so that the voltage output is independent of the magnitude and the phase angle of the load. In order to achieve a correct distribution of the reactive load between the two generators 2a and 2b, each of the current transformers 60 or 6b affected by the load current is provided with a special secondary winding 16a, 17a, 18a or 16b, 17b, 18b, and each of these secondary windings is connected in parallel with the corresponding secondary winding of the corresponding current transformer of the other generator, so that the secondary winding 16a is connected in parallel with the secondary winding 16b, the winding 17a with the winding 17b and 18a with 18 b. This creates equalizing circuits between the current transformers of the generators, so that the load current-dependent exciter component from a current transformer in one generator is always in a fixed ratio to the load current-dependent exciter component of the corresponding current transformer in the other generator. This ratio is determined by the turns ratio between the secondary winding supplying the exciter component and the secondary winding connected in parallel, so that with the same size of the turns ratio for the current transformers of the two generators, the load current-dependent exciter component is the same in both generators. Since the load-dependent exciter components are in a certain ratio to one another, the excitations of the generators are also dependent on one another, which is why each generator emits a certain part of the total reactive load and a fixed distribution of the reactive load to the generators is achieved. The parallel connection of the transformers is carried out by means of a switch 19a or 19b of each generator, which is coupled to the switch 3a or b, so that when a generator is switched off from the common network 1, its current transformers from the parallel connection with the current transformers of the other generators be switched off. Patent claims:

1. Arrangement for parallel operation of self-excited synchronous generators, each with two groups of current converters, one of which is influenced by the load current of the generator and the other by the voltage of the generator, with both current converter groups after superimposing their currents jointly feed the excitation winding of the generator via rectifiers , characterized in that each current transformer influenced by the load current has, in addition to the secondary winding feeding the excitation winding, an additional secondary winding which is connected in parallel with corresponding additional secondary windings on the corresponding current transformers of the other generators operating in parallel.

2. Arrangement according to claim 1, characterized in that each generator has a switch for the parallel connection of its current transformer influenced by the load current with the corresponding current transformers of the generators operating in parallel and this switch is synchronized with the main switch of the generator so that when the generator is switched off In the common network of the generators working in parallel, the current transformers of the generator, which are influenced by the load current, are switched off simultaneously by the corresponding current transformers of the generators working in parallel.

Considered publications: German Patent Specifications Nos. 946641, 761904.

Older patents considered: German Patent No. 960 834.

For this purpose, 1 sheet of drawings