Indian Patents. 269656:EQUIPMENT FOR REGULATING ELECTRICAL VOLTAGE

Title of Invention	EQUIPMENT FOR REGULATING ELECTRICAL VOLTAGE
Abstract	The invention relates to a device for regulating the electrical voltage in power mains, comprising a regulating transformer. Optionally interconnecting only three winding taps and a separate reactor winding with a total of four switching elements, enables five different voltage levels to be set.

Full Text	Equipment for regulating electrical voltage The invention relates to equipment for regulating the electrical voltage in supply mains. In the case of present-day widespread central energy supply systems voltage regulation is usually carried out by means of regulating transformers in the central mains junctions of the respective high-voltage or medium-voltage mains. For this purpose the regulating windings of the respective regulating transformers are provided with winding taps; an uninterrupted switching over between adjacent winding taps under load can be carried out by means of tap changers. Tap changers suitable for that purpose can be basically divided into two kinds: those of the type of quick-action resistance switches in which ohmic switch-over resistances loadable only transiently are present for limitation of the circuit current flowing during switching over and accordingly a rapid switching over between the winding taps takes place and those of the type of reactor switches in which inductive switching-over impedances are provided, whereby a slow and continuous switching over is also possible. However, in the case of the described voltage regulation in the field of high-voltage or medium-voltage mains it is not readily possible with decentral energy supply systems to perform regulation at distribution transformers. So-termed 'voltage regulators' have been used, particularly in the United States, for this regulation - in the proximity of the consumer - of the low voltage in decentral energy supply mains. Most of the presently usual Voltage regulators' are single phase, have inductive switch-over impedances, also termed reactor or reactor winding, and allow a voltage regulation in 32 steps each at 5/8%, i.e. in the range of +/-10%. Another form of these 'voltage regulators' is that of the type 'Auto-Booster' (Registered Trade Mark). These apparatus are of substantially simpler construction and enable upward regulation in 4 steps each of 214% or 11/4%, i.e. in total +10% or +6%. Another approach to voltage regulation, carried out in the proximity of the consumer, in the low-voltage field is described in WO 01/33308 and WO 03/044611. These two applications are based on the general idea of providing a regulating transformer with only a few taps. The individual part windings are then selectably looped in by way of a changeover switch, wherein the regulating transformer is to have a leakage impedance of such height that the circuit current in the case of a short circuit of adjacent taps of the part windings - which transiently occurs on switching over under load - is to be limited to the order of magnitude of the nominal current. The typical switch-over resistances of classic tap changers can thus be eliminated. In this arrangement, which is to be suitable not only for construction of the regulating transformer as an autotransformer, but also as a separate-winding transformer, numerous different embodiments of the changeover switch are possible. Thus, it is proposed to use as changeover switch a load changeover switch, which is without resistance contacting and which has exclusively main contacts, of a tap changer. According to other proposals the changeover switch shall be constructed as a multi-stage cam switch selectably also formed from a chain of relays or contactors or exclusively also consisting of a chain of electronic switches, particularly thyristor switches. The number of required switching elements of the changeover switch then corresponds with the number of possible settings. It is disadvantageous with this known state of the art that at least in the case of the separate-winding transformer a separate main winding and regulating winding have to be present. In order to drive the leakage inductance of each step to such a height that the step short-circuit current reaches only the height of the nominal current a short leakage channel is required. From that results a separate, short regulating winding which increases the width and depth of the transformer. This additional outlay on transformer costs in many cases exceeds the advantage due to the omitted switch-over resistances. Moreover, the regulating method becomes difficult; the known arrangement is particularly unsuitable for parallel circuits. It is the object of the invention to indicate simple and economic equipment for regulating the electrical voltage for distributor transformers and voltage regulators with as few switching elements as possible. This object is fulfilled by equipment with the features of the first claim. The subclaims relate to particularly advantageous developments of the invention. The equipment according to the invention is preferably provided for regulation of distributor transformers with a small regulating range of, for example, +/- 5% in 2.5% steps, thus in total, for example, 5 steps. The equipment according to the invention is suitable not only for oil transformers, but also for dry transformers. The particular advantage thereof consists in that only a minimum enlargement of the dimensions of the respective distributor transformer is required and a high level of serviceability and operational reliability is given. This is due to the fact that the equipment according to the invention is conceived as switching apparatus dispensing with mechanically moved selectors or load selectors of an on-load tap changer. Moreover, the equipment according to the invention has a small degree of complexity, in particular only a few components and also switching elements. For example, only four switching elements are required for an embodiment with five selectable voltage steps as explained in more detail further below. These switching elements can, with particular advantage, be each constructed as an antiparallel thyristor pair or also as vacuum switching cells. The invention shall be explained in more detail in the following by way of example with reference to drawings, in which: Fig. 1 shows the schematic circuit arrangement of first equipment according to the invention; Fig. 2 shows a table of the achievable voltage steps with this equipment in dependence on the setting of the individual switching elements; Fig. 3 shows the respective settings of the individual switching elements with these voltage steps; Fig. 4 shows further equipment according to the invention for voltage regulation on the load side of a voltage regulator; Fig. 5 shows further equipment according to the invention for voltage regulation on the primary side of a voltage regulator; Fig. 6 shows further equipment according to the invention with switching elements of alternative construction; and Fig. 7 shows further equipment according to the invention with an extended switching arrangement. First equipment according to the invention is schematically illustrated in Figure 1. A main winding 1 of a regulating transformer, the winding end 2 of which is led to the centre of a separate regulating winding 3 of the regulating transformer, is shown. The regulating winding 3 here has three separate taps A1 ... A3. The taps A1 and A3 are respectively disposed at the opposite ends of the regulating winding 3 and the tap A2 exactly in the centre, at the place of which the connection with the winding end 2 of the main winding 1 is present. The regulating winding 3 is dimensioned in such a manner that the effective winding length between the taps A1 and A2 and also between the taps A2 and A3 here corresponds in each instance with 5% of the winding length of the main winding 1. Obviously also other winding lengths are possible. Each of the taps A1 ... A3 is connected with the input of a switching element, here a vacuum switch V1 ... V3. The output of the first vacuum switch V1, which is connected with the tap A1 at the first winding end of the regulating winding 3, and the output of the second vacuum switch V2, which is connected with the tap A2 in the centre of the regulating winding 3, lead to the two ends of a reactor winding 4; parallel thereto a further switching element, here a further vacuum switch V4, is arranged between these two outputs. The output of the third vacuum switch V3, which is connected with the tap A3 at the other end of the regulating winding 3, is electrically connected with the output of the first vacuum switch VI The centre of the reactor winding 4 leads to the shunt. For this purpose a tap 5 is provided at the reactor winding 4. Through corresponding actuation of the vacuum switches V1 ... V4 the voltage in this example can thus be regulated to the range of +/- 5% in 2.5% steps. Fig. 2 shows for the example shown in Figure 1 a table of the five possible different voltage steps in dependence on the setting of the respective vacuum switches V1 ... V4. In that case c signifies the closed position ('closed') and o stands for the open position of the respective switch. It can be seen that with these four vacuum switches a total of five voltage steps can be set. This is due to the fact that at the taps A1 and A3 it is possible to tap off each time a voltage at around +/- 5% relative to that at the tap A2 and through appropriate electrical coupling of the reactor winding 4 again half thereof, consequently 2.5%, can be superimposed. The control of the vacuum switches V1 ... V4 is possible in simple manner, for example by cam switches, since a very simple actuating sequence, depending on the switching direction of 'higher voltage' or 'lower voltage', results through simple switching on or switching off. Figure 3 shows the different settings of the vacuum switches V1 ... V4 of the circuit, which is shown in Figure 1 and explained above, with the individual voltage steps, thus as is shown in the table in Figure 2. Figure 4 shows an arrangement according to the invention as a component of a voltage regulator for regulation on the load side. It can be seen that the input voltage Us is present at the main winding 1, the end of which leads to the centre tap of the regulating winding 3, which is the illustrated tap A2. Again, the taps A1 and A3 are provided at the two ends of the regulating winding 3 each at the winding spacing of 5% of the main winding. The position and function of the vacuum switches V1 ... V4 were already explained, equally the illustrated reactor winding 4. Additionally illustrated here are a current converter 6 and a voltage converter 7 on the load side. Thus, in known manner the actual values of current and voltage of the load can be ascertained. With the help of a regulator, which is not illustrated here and which is known per se, a target/actual value comparison is then undertaken and in the result a decision is made about necessary regulation in the direction of 'higher' or 'lower'. A corresponding change in the switching states of the vacuum switches V1 ... V4 is thereupon undertaken as illustrated in Figure 2. If the control of these vacuum switches V1 ... V4 is carried out by a cam control, then a rotation of the switching cam through 72 degrees is carried out quite simply for directionally dependent actuation. Figure 5 shows an arrangement according to the invention for regulation on the input (source) side of a voltage regulator. The function is unchanged. Figure 6 shows a further arrangement according to the invention, here with thyristor pairs Th1 ... Th4, as switching elements, connected in antiparallel manner. Within the scope of the invention the described switching elements can be realised not only by vacuum switches as explained further above, but also by mechanical switches or even by thyristor switches. The embodiment, which is shown here, with thyristor switches has the advantage that the arrangement according to the invention gives overall a completely static switch without any form of mechanically moved actuating elements. For drive control of the thyristor switches Th1 ... Th4 the table shown in Figure 2 can, for example, be readily converted by the expert into an electrical drive control logic system. It is also possible within the scope of the invention to extend the switching arrangement, which is illustrated in Figure 1, in cascade manner in that more than three taps are provided at the regulating winding 3 and each of these additional taps is similarly electrically coupled by an own switching element. An example for that with here only one additional tap A4 is shown in Figure 7. The regulating winding 3 in the case of such a form of embodiment of the invention is so dimensioned that the winding length between all taps A1 ... A4 is the same each time, for example amounts each time to 5% of the winding length of the main winding 1. It is thus readily possible for the expert to extend the corresponding state table - analogously to the illustration shown in Figure 2 - in correspondence with the additional voltage steps achievable in accordance with the invention. This cascade principle can be extended as desired. Patent Claims 1. Equipment for regulating the electrical voltage in supply mains with a regulating transformer, wherein the regulating transformer in each phase has a main winding and a separate regulating winding which is provided with taps and wherein the individual taps can be electrically coupled by switching elements and are connectible with a shunt, characterised in that the regulating winding (3) has three taps (A1 ... A3), that the first and the third tap (A1 and A3) are each arranged at a respective winding end of the regulating winding (3) and the second tap (A2) is arranged exactly in the winding centre of the regulating winding (3), that the end of the main winding (1) is connected with the second tap (A2), that the regulating winding (3) is so dimensioned that the winding length between the first and second tap (A1 and A2) and also between the second and third tap (A2 and A3) each amounts to X% of the winding length of the main winding (1), wherein X is a natural number, that the first tap (A1) is electrically connected with the input of a first switching element (V1, Th1), the second tap (A2) with the input of a second switching element (V2, Th2) and the third tap (A3) with the input of a third switching element (V3, Th3), that the output of the first switching element (V1, Th1) and the output of the second switching element (V2, Th2) are each connected with a respective one of the two ends of a reactor winding (4), that the output of the third switching element (V3, Th3) is electrically connected with the output of the first switching element (V1, Th1), that a further switching element (V4, Th4) is arranged parallel to the reactor winding (4) and that exactly the centre of the reactor winding (4) leads to the shunt. 2. Equipment according to claim 1, characterised in that the value of X is equal 5. 3. Equipment according to claim 1 or 2, characterised in that vacuum switches (V1 ... V4) are provided as switching elements. 4. Equipment according to claim 1 or 2, characterised in that semiconductor switches, particularly thyristor switches (Th1 ... Th4), are provided as switching elements.

Full Text

Equipment for regulating electrical voltage
The invention relates to equipment for regulating the electrical voltage in supply mains.
In the case of present-day widespread central energy supply systems voltage regulation is usually carried out by means of regulating transformers in the central mains junctions of the respective high-voltage or medium-voltage mains. For this purpose the regulating windings of the respective regulating transformers are provided with winding taps; an uninterrupted switching over between adjacent winding taps under load can be carried out by means of tap changers.
Tap changers suitable for that purpose can be basically divided into two kinds: those of the type of quick-action resistance switches in which ohmic switch-over resistances loadable only transiently are present for limitation of the circuit current flowing during switching over and accordingly a rapid switching over between the winding taps takes place and those of the type of reactor switches in which inductive switching-over impedances are provided, whereby a slow and continuous switching over is also possible.
However, in the case of the described voltage regulation in the field of high-voltage or medium-voltage mains it is not readily possible with decentral energy supply systems to perform regulation at distribution transformers.
So-termed 'voltage regulators' have been used, particularly in the United States, for this regulation - in the proximity of the consumer - of the low voltage in decentral energy supply mains. Most of the presently usual Voltage regulators' are single phase, have inductive switch-over impedances, also termed reactor or reactor winding, and allow a voltage regulation in 32 steps each at 5/8%, i.e. in the range of +/-10%.
Another form of these 'voltage regulators' is that of the type 'Auto-Booster' (Registered Trade Mark). These apparatus are of substantially simpler construction and enable upward regulation in 4 steps each of 214% or 11/4%, i.e. in total +10% or +6%.
Another approach to voltage regulation, carried out in the proximity of the consumer, in the low-voltage field is described in WO 01/33308 and WO 03/044611. These two applications are based on the general idea of providing a regulating transformer with only

a few taps. The individual part windings are then selectably looped in by way of a changeover switch, wherein the regulating transformer is to have a leakage impedance of such height that the circuit current in the case of a short circuit of adjacent taps of the part windings - which transiently occurs on switching over under load - is to be limited to the order of magnitude of the nominal current. The typical switch-over resistances of classic tap changers can thus be eliminated. In this arrangement, which is to be suitable not only for construction of the regulating transformer as an autotransformer, but also as a separate-winding transformer, numerous different embodiments of the changeover switch are possible. Thus, it is proposed to use as changeover switch a load changeover switch, which is without resistance contacting and which has exclusively main contacts, of a tap changer. According to other proposals the changeover switch shall be constructed as a multi-stage cam switch selectably also formed from a chain of relays or contactors or exclusively also consisting of a chain of electronic switches, particularly thyristor switches. The number of required switching elements of the changeover switch then corresponds with the number of possible settings.
It is disadvantageous with this known state of the art that at least in the case of the separate-winding transformer a separate main winding and regulating winding have to be present. In order to drive the leakage inductance of each step to such a height that the step short-circuit current reaches only the height of the nominal current a short leakage channel is required. From that results a separate, short regulating winding which increases the width and depth of the transformer. This additional outlay on transformer costs in many cases exceeds the advantage due to the omitted switch-over resistances. Moreover, the regulating method becomes difficult; the known arrangement is particularly unsuitable for parallel circuits.
It is the object of the invention to indicate simple and economic equipment for regulating the electrical voltage for distributor transformers and voltage regulators with as few switching elements as possible.
This object is fulfilled by equipment with the features of the first claim. The subclaims relate to particularly advantageous developments of the invention.
The equipment according to the invention is preferably provided for regulation of distributor transformers with a small regulating range of, for example, +/- 5% in 2.5% steps, thus in

total, for example, 5 steps. The equipment according to the invention is suitable not only for oil transformers, but also for dry transformers. The particular advantage thereof consists in that only a minimum enlargement of the dimensions of the respective distributor transformer is required and a high level of serviceability and operational reliability is given. This is due to the fact that the equipment according to the invention is conceived as switching apparatus dispensing with mechanically moved selectors or load selectors of an on-load tap changer. Moreover, the equipment according to the invention has a small degree of complexity, in particular only a few components and also switching elements. For example, only four switching elements are required for an embodiment with five selectable voltage steps as explained in more detail further below. These switching elements can, with particular advantage, be each constructed as an antiparallel thyristor pair or also as vacuum switching cells.
The invention shall be explained in more detail in the following by way of example with reference to drawings, in which:
Fig. 1 shows the schematic circuit arrangement of first equipment according to the
invention;
Fig. 2 shows a table of the achievable voltage steps with this equipment in
dependence on the setting of the individual switching elements;
Fig. 3 shows the respective settings of the individual switching elements with
these voltage steps;
Fig. 4 shows further equipment according to the invention for voltage regulation
on the load side of a voltage regulator;
Fig. 5 shows further equipment according to the invention for voltage regulation
on the primary side of a voltage regulator;
Fig. 6 shows further equipment according to the invention with switching elements
of alternative construction; and

Fig. 7 shows further equipment according to the invention with an extended
switching arrangement.
First equipment according to the invention is schematically illustrated in Figure 1. A main winding 1 of a regulating transformer, the winding end 2 of which is led to the centre of a separate regulating winding 3 of the regulating transformer, is shown. The regulating winding 3 here has three separate taps A1 ... A3. The taps A1 and A3 are respectively disposed at the opposite ends of the regulating winding 3 and the tap A2 exactly in the centre, at the place of which the connection with the winding end 2 of the main winding 1 is present. The regulating winding 3 is dimensioned in such a manner that the effective winding length between the taps A1 and A2 and also between the taps A2 and A3 here corresponds in each instance with 5% of the winding length of the main winding 1. Obviously also other winding lengths are possible.
Each of the taps A1 ... A3 is connected with the input of a switching element, here a vacuum switch V1 ... V3. The output of the first vacuum switch V1, which is connected with the tap A1 at the first winding end of the regulating winding 3, and the output of the second vacuum switch V2, which is connected with the tap A2 in the centre of the regulating winding 3, lead to the two ends of a reactor winding 4; parallel thereto a further switching element, here a further vacuum switch V4, is arranged between these two outputs. The output of the third vacuum switch V3, which is connected with the tap A3 at the other end of the regulating winding 3, is electrically connected with the output of the first vacuum switch VI The centre of the reactor winding 4 leads to the shunt. For this purpose a tap 5 is provided at the reactor winding 4.
Through corresponding actuation of the vacuum switches V1 ... V4 the voltage in this example can thus be regulated to the range of +/- 5% in 2.5% steps.
Fig. 2 shows for the example shown in Figure 1 a table of the five possible different voltage steps in dependence on the setting of the respective vacuum switches V1 ... V4. In that case c signifies the closed position ('closed') and o stands for the open position of the respective switch.
It can be seen that with these four vacuum switches a total of five voltage steps can be set. This is due to the fact that at the taps A1 and A3 it is possible to tap off each time a

voltage at around +/- 5% relative to that at the tap A2 and through appropriate electrical coupling of the reactor winding 4 again half thereof, consequently 2.5%, can be superimposed.
The control of the vacuum switches V1 ... V4 is possible in simple manner, for example by cam switches, since a very simple actuating sequence, depending on the switching direction of 'higher voltage' or 'lower voltage', results through simple switching on or switching off.
Figure 3 shows the different settings of the vacuum switches V1 ... V4 of the circuit, which is shown in Figure 1 and explained above, with the individual voltage steps, thus as is shown in the table in Figure 2.
Figure 4 shows an arrangement according to the invention as a component of a voltage regulator for regulation on the load side. It can be seen that the input voltage Us is present at the main winding 1, the end of which leads to the centre tap of the regulating winding 3, which is the illustrated tap A2. Again, the taps A1 and A3 are provided at the two ends of the regulating winding 3 each at the winding spacing of 5% of the main winding. The position and function of the vacuum switches V1 ... V4 were already explained, equally the illustrated reactor winding 4. Additionally illustrated here are a current converter 6 and a voltage converter 7 on the load side. Thus, in known manner the actual values of current and voltage of the load can be ascertained. With the help of a regulator, which is not illustrated here and which is known per se, a target/actual value comparison is then undertaken and in the result a decision is made about necessary regulation in the direction of 'higher' or 'lower'. A corresponding change in the switching states of the vacuum switches V1 ... V4 is thereupon undertaken as illustrated in Figure 2. If the control of these vacuum switches V1 ... V4 is carried out by a cam control, then a rotation of the switching cam through 72 degrees is carried out quite simply for directionally dependent actuation.
Figure 5 shows an arrangement according to the invention for regulation on the input (source) side of a voltage regulator. The function is unchanged.
Figure 6 shows a further arrangement according to the invention, here with thyristor pairs Th1 ... Th4, as switching elements, connected in antiparallel manner.

Within the scope of the invention the described switching elements can be realised not only by vacuum switches as explained further above, but also by mechanical switches or even by thyristor switches. The embodiment, which is shown here, with thyristor switches has the advantage that the arrangement according to the invention gives overall a completely static switch without any form of mechanically moved actuating elements. For drive control of the thyristor switches Th1 ... Th4 the table shown in Figure 2 can, for example, be readily converted by the expert into an electrical drive control logic system.
It is also possible within the scope of the invention to extend the switching arrangement, which is illustrated in Figure 1, in cascade manner in that more than three taps are provided at the regulating winding 3 and each of these additional taps is similarly electrically coupled by an own switching element. An example for that with here only one additional tap A4 is shown in Figure 7. The regulating winding 3 in the case of such a form of embodiment of the invention is so dimensioned that the winding length between all taps A1 ... A4 is the same each time, for example amounts each time to 5% of the winding length of the main winding 1. It is thus readily possible for the expert to extend the corresponding state table - analogously to the illustration shown in Figure 2 - in correspondence with the additional voltage steps achievable in accordance with the invention. This cascade principle can be extended as desired.

Patent Claims
1. Equipment for regulating the electrical voltage in supply mains with a regulating
transformer, wherein the regulating transformer in each phase has a main winding and a
separate regulating winding which is provided with taps and wherein the individual taps
can be electrically coupled by switching elements and are connectible with a shunt,
characterised in that the regulating winding (3) has three taps (A1 ... A3), that the first and
the third tap (A1 and A3) are each arranged at a respective winding end of the regulating
winding (3) and the second tap (A2) is arranged exactly in the winding centre of the
regulating winding (3), that the end of the main winding (1) is connected with the second
tap (A2), that the regulating winding (3) is so dimensioned that the winding length between
the first and second tap (A1 and A2) and also between the second and third tap (A2 and
A3) each amounts to X% of the winding length of the main winding (1), wherein X is a
natural number, that the first tap (A1) is electrically connected with the input of a first
switching element (V1, Th1), the second tap (A2) with the input of a second switching
element (V2, Th2) and the third tap (A3) with the input of a third switching element (V3,
Th3), that the output of the first switching element (V1, Th1) and the output of the second
switching element (V2, Th2) are each connected with a respective one of the two ends of a
reactor winding (4), that the output of the third switching element (V3, Th3) is electrically
connected with the output of the first switching element (V1, Th1), that a further switching
element (V4, Th4) is arranged parallel to the reactor winding (4) and that exactly the centre
of the reactor winding (4) leads to the shunt.
2. Equipment according to claim 1, characterised in that the value of X is equal 5.
3. Equipment according to claim 1 or 2, characterised in that vacuum switches (V1 ...
V4) are provided as switching elements.
4. Equipment according to claim 1 or 2, characterised in that semiconductor switches,
particularly thyristor switches (Th1 ... Th4), are provided as switching elements.

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Patent Number

269656

Indian Patent Application Number

1789/CHENP/2007

PG Journal Number

45/2015

Publication Date

06-Nov-2015

Grant Date

30-Oct-2015

Date of Filing

30-Apr-2007

Name of Patentee

MASCHINENFABRIK REINHAUSEN GMBH

Applicant Address

Falkensteinstrasse 8, 93095 Regensburg

Inventors:

#	Inventor's Name	Inventor's Address
1	DOHNAL, Dieter	Stefan-Zweig-Str. 1, 93138 Lappersdorf

PCT International Classification Number

G05F 1/20

PCT International Application Number

PCT/EP2005/007999

PCT International Filing date

2005-07-22

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	102004046926.1	2004-09-28	Germany