WO1996024146A1

WO1996024146A1 - Device for voltage control

Info

Publication number: WO1996024146A1
Application number: PCT/EP1996/000428
Authority: WO
Inventors: Siegfried Plöbst; Robert Renner
Original assignee: Ploebst Siegfried; Robert Renner
Priority date: 1995-02-02
Filing date: 1996-02-01
Publication date: 1996-08-08
Also published as: AU4717396A; HUP9702427A3; ATE174152T1; HUP9702427A2; EP0807311B1; EP0807311A1

Abstract

A device for uninterrupted voltage control with an autotransformer has a first contact member (11), with which the load section (4) of the transformer can be bridged, and a second contact member (9), with which the primary winding (2) of the transformer can be deactivated. When switching over to changing the voltage to the consumer (6), both contact members (9, 11) are controlled in such a way that the load section (4) forms a choke.

Description

Voltage regulation device

The invention relates to a device for uninterrupted voltage control with an autotransformer.

A street lighting system is generally operated at full luminous intensity, that is to say with mains voltage, during the rush hour in the evening and with reduced voltage in the quiet night time. In the case of gas discharge lamps, the switchover from the mains voltage to the reduced voltage and vice versa must be carried out without interruption, otherwise the lamp will fail.

According to the prior art, infinitely variable transformers are used, for. B. an autotransformer, which has an iron core with only one winding, which is connected on the input side to the phase of the network and the neutral conductor and on the output side to a tap of the transformer winding and the neutral conductor. The voltage to be taken is obtained by tapping the line leading to the phase of the consumer leads, obtained on a turn of the winding. The ratio of the voltage to be reduced to the nominal voltage corresponds to the ratio of the number of turns located between the output side of the winding and the stripped turn to the total number of turns of the winding. The entire winding thus forms the primary winding, while the winding section between the tap and the neutral conductor forms the secondary winding of the economy transformer. The winding section of the primary winding between the phase of the network and the tap is also referred to as the load section.

In order to make the transformer controllable, it is known to use bare wires for the winding and a pickup for the tap, which slides along the winding over the bare wires. Since the entire load current flows through the customer, it must be designed accordingly expensive. In addition, a motor is required to move the pickup, and the pickup is worn out by the sliding contact of the winding.

Furthermore, variable transformers are known in which the winding is provided with taps. So that there is no interruption during the switching and no short-circuiting of the turns to be switched on and off, two switching elements are provided in each branch between the tap and the supply line to the consumer, the second switching element bridging a resistor. The switching process begins with the fact that in the connected, first branch the Resistor is switched on and then the connection to the new tap is established via an equally large resistor in the other branch. The turns to be connected between the two taps are now short-circuited, but the two resistors are in the short-circuit and limit the short-circuit current. If the first switching element in the first branch is now opened, the new tap is already connected. Your direct connection to the outer supply line is finally achieved by closing the second switching element in the second branch. The known variable transformer with tap changer is complex and correspondingly expensive due to the two switching elements and the resistance at each tap.

In order to save electricity costs, it is known to distribute the power peaks caused by the accidental switching on of several devices by power control. For this purpose, a control line is drawn to the devices in accordance with the prior art and intervenes directly in the operation of the respective device, for example by clocked disconnection. The subsequent installation of control lines is associated with considerable effort. This regulation is also unsuitable for devices with a more complicated mode of operation.

The object of the invention is to provide a simply constructed transformer for voltage regulation, which enables switching without voltage interruption for the consumer. This is achieved according to the invention with the device characterized in claim 1. Advantageous refinements of the invention are given in subclaims 2 to 7. Preferred applications of the device according to the invention are specified in claims 8 to 10.

The one, first switching element of the transformer of the device according to the invention is preferably used to bridge the load section of the transformer and the further switching element is used to put the primary winding out of operation. It can also be provided in the control section. When switching to change the voltage at the consumer, the two switching elements are controlled so that the load section forms a choke. In this way, the consumer is always supplied with the minimum voltage during the switching process. If the switching between individual switching elements takes place practically simultaneously, the throttling effect can hardly come into play. The short circuit can then be so brief that the short circuit current cannot increase. The switching elements can therefore be controlled so that a short circuit is limited in time so that damage to the switching elements or lines is prevented.

In the controllable transformer, the primary and / or secondary winding preferably consists at least partially of individual sections, which can be interconnected in a combination corresponding to the voltage to be reduced. At least one section has the first switching element in its current path and the further switching element between its input and the output. The switching elements are preferably formed by contactors. Each individual section can have a resistor, a choke and / or a fuse, preferably a line with which a switching element is provided, with which the consumer can be connected to the phase of the network. The further switching element can be arranged in the line which connects the load section on the output side to the consumer.

The transformer winding of the autotransformer preferably has a load section connected on the input side to the phase of the network and on the output side to the phase of the consumer and a control section connected on the output side to the neutral conductor, which control section consists at least partially of the individual sections which, in a combination corresponding to the voltage to be taken off, with the Neutral conductors are connectable. The control section preferably consists of a first part and a second part. The second part is arranged between the first part and the load section. The number of turns of the second part connected to the neutral conductor can not be changed, while the number of turns of the first part which can be connected to the neutral conductor can be changed.

The consumer can be, in particular, a lighting system with gas discharge lamps. O

If the gas discharge lamps are operated at full light intensity, that is to say with mains voltage, the first switching element of the device according to the invention is closed and the second switching element is open. If the brightness is to be reduced, that is to say a voltage drop corresponding to the transformation ratio of the transformer, the first switching element must be opened and the second switching element must be closed. This requires a certain switchover time. The two switching elements are preferably formed by a contactor with NO contacts and / or a contactor with NO contacts and NC contacts. With a contactor as a switching element, the changeover time is a few milliseconds. In order to prevent the lamp from failing, the first switching element in the primary circuit is therefore opened according to the invention. The load section of the transformer, ie the section over which the load current flows, thus changes into a choke. In this way, failure of the lamp during the switching process is prevented. Then the further switching element is closed, which results in a voltage drop corresponding to the transformation ratio of the transformer.

In addition to the control of a lighting system, there are a large number of further preferred possible uses for the device according to the invention.

Thus, the device according to the invention can advantageously be used for power control, also called load management. You can do one Consumer or a consumer group are upstream.

According to the formula P = U / R, the power consumption (P) is proportional to the square of the voltage (U). That is, a relatively small change in voltage causes a relatively large change in power consumption for an ohmic consumer. It should be noted that the devices are usually fully functional within a voltage tolerance of, for example, 230 V ± 10%.

With the device according to the invention, load management is thus possible without control lines and without interfering with the operating mode of the consumer. Conversely, in the event of low load, the device according to the invention can increase the voltage applied to the consumer compared to the supply voltage. The device according to the invention is controlled as a function of the load.

If in an electrical system with multiple consumers, e.g. B. at a transformer station in the electrical supply network, the voltage drops within the tolerable per se, it can come to a lower voltage below the permitted level for consumers located further away. The device according to the invention can therefore also be used advantageously, for example, for voltage compensation in the electrical supply network or in general in electrical systems. The device according to the invention can be used not only to regulate the voltage downwards, but also to increase the voltage. This can be done by switching the transformer in reverse order (load and nominal voltage interchanged) between consumer and supply voltage.

The invention is explained in more detail below with reference to the drawing, for example, in which FIGS. 1 to 5 each show a different circuit of an autotransformer according to the invention.

According to Figure 1, the autotransformer consists of a closed iron core 1 with a winding 2. The entire winding 2 forms the primary winding of the autotransformer, the section 4 of the winding 2 between the phase L of the network and the tap 3 of the line 5 to the gas discharge lamp 6 Section of the load over which the load current IL flows to the lamp 6. The winding section 7 between the tap 3 and the neutral conductor N forms the secondary winding of the autotransformer, via which the magnetizing current IM and a compensation current dependent on the load flows.

The phase L of the network is connected to line 5 via a bypass line 8. The bypass line 8 has a first switching element 9, so that it bridges the load section 4 when the switching element 9 is closed. The output of the secondary winding 7 is with connected to the neutral conductor N via a line 10 which has a second switching element 11.

The two switching elements 9 and 11 are formed by a contactor, that is to say a remotely operated electromagnetic switch, preferably by the make or break contact of one and the same contactor, or by the two make contacts of a contactor, as shown in the drawing.

The nominal voltage is designated with Ul, and the load voltage with U2. When the switching element 9 is open and the switching element 11 is closed, that is to say when the contactor is not actuated, the lamp 6 is operated with the voltage U2 <Ul reduced by the transformer. The contactor is actuated to switch the load voltage U2 to the nominal voltage Ul. The switching elements 9, 11, that is, the closer and the opener of the contactor are controlled so that the switching element 11 is opened before the switching element 9 is closed. Thus, the load section 4 acts briefly during the switching time of the contactor, i. H. for example 5 to 50 milliseconds, as a choke. The choke leads to a voltage drop. However, this is low, so that the lamp 6 is supplied with a sufficient voltage U2 during the switching process. Thereafter, the switching element 9 closes, as a result of which the load section 4 or the inductor is bridged and the lamp 6 is thus operated with the nominal voltage Ul, that is to say U2 = Ul.

If you want to switch from the nominal voltage Ul to a reduced voltage U2, the contactor actuated so that the switching element 9 is opened, whereby the load section 4 forms a throttle. The contactor then closes the switching element 11. This enables an uninterrupted switching from U2 = Ul to U2 <Ul and vice versa.

If the nominal voltage z. B. 220 V, the reduced voltage z. B. 180 V. In any case, care must be taken that the reduced voltage U2 is greater than the minimum voltage required for operating the gas discharge lamp 6, preferably 5 V to 10 V greater than the minimum voltage, in order to take fluctuations in the nominal voltage into account.

With U2 = Ul, the load section 4 of the transformer is bridged and the primary winding 2 or the control section 7 is deactivated. When switching to the reduced voltage U2 <Ul and from the reduced voltage to the voltage U2 = Ul, the two switching elements 9, 11 are each controlled so that the load section 4 forms a choke upstream of the gas discharge lamps 6.

FIG. 2 shows a transformer with a primary winding 12 and a secondary winding 13 on a closed iron core 1. Through lines 15 and 16, this transformer is also connected as an economy transformer.

The secondary winding 13 forms the load section of the transformer, that is to say the section over which the load current IL flows via the line 14 to the lamp 6. The secondary winding 13 can be bridged with a bypass line 8 with a first switching element 9.

The primary winding 12 is connected on the input side to phase L of the network via a line 15 in which the second switching element 11 is arranged. The output side of the primary winding 12 is connected to the neutral conductor N via a line 16.

When the lamp 6 is operated with a reduced voltage U2 <Ul, the switching element 9 is open and the switching element 11 is closed. To switch to a voltage U2 = Ul, the switching element 11, that is, the make contact of the contactor, is opened first before the switching element 9, that is, the second make contact of the contactor, is closed. During this switching time of a few milliseconds, the secondary winding 13 switches to choke operation, which ensures a sufficient voltage to operate the lamp 6. The switching element 9 then closes, as a result of which the lamp 6 is operated with the nominal voltage U 1, that is to say U 2 = U 1.

If the load voltage U2 is to be switched to a reduced voltage U2 <Ul, the switching element 9 is first opened so that the secondary winding 13 acts as a choke, whereupon the switching element 11 is closed.

This means that when U2 = Ul, the secondary winding 13, that is to say the load section of the transformer, is bridged, while the primary winding 12 is put out of operation. When switching to the reduced voltage U2 < Ul and from the reduced voltage to U2 = Ul, the two switching elements 9, 11 are each controlled so that the secondary winding 13 forms a choke upstream of the gas discharge lamp 6.

FIG. 3 shows an autotransformer with which the load voltage U2 can be regulated in fine stages. The secondary winding 7 according to FIG. 1 is replaced by a control section 17.

The control section 17 is formed from a first part 18 and a second part 19. The turns of the second part 19 connect to the turns of the load section 4. The turns of the first part 18 of the control section 17 consist of several individual sections I to IV.

Each individual section I to IV has a first switching element 24 to 27 in its current path. Furthermore, a switching element 28 to 31 is provided between the input side E and the output side A of each individual section I to IV. A line 32 to 35 leads from the input side E of each individual section I to IV to the windings of the relevant individual section I to IV, the first switching element 24 to 27 being arranged in the lines 32 to 35. Another line 36 to 39 leads from the turns of the respective individual section I to IV to the output side A of the same.

The input side E of the first individual section I is via a line 40 to the output side of the second Part 19 of the control section 17 is connected, while the output side A of the individual section IV facing away from the second part 19 is connected to the neutral conductor N via a line 41, the switching element 11 being arranged in the line 41. The switching elements 28 to 31 are located between the lines 32 and 36, 33 and 37, 34 and 38 and 35 and 39 of each individual section I to IV.

Each individual section I to IV has a different number of turns. For example, the individual section I can have ten, the individual section II twenty, the individual section III forty and the individual section IV eighty turns.

The number of turns NM of the control section 17, which are connected to the neutral conductor, can thus be changed in accordance with the voltage U2 to be decreased. The number of turns NM of the control section consists of the unchangeable number of turns NM const. Of the second part 19 and the changeable number of turns NM v of the individual sections I to IV, which are connected to the neutral conductor N.

That is, If, for example, the number of turns NM of the control section 17 is to be composed of the number of turns NM const. of the second part 19 and the ten turns of the individual section I, the switching element 24 of the individual segment I is closed and the switching element 28 between the input E and the output A of the individual segment I opened while the switching elements 25, 26, 27 of the remaining individual sections II to IV opened and the switching elements 29 to 31 between the input E and the output A of the individual sections II to IV are closed.

For example, if the number of turns NM of the control section is to be 17 NM constant plus seventy turns, the switching elements 24, 25, 26 of the individual sections I to III are closed and the switching elements 28, 29, 30 between the input E and the output A of the individual sections I open to III, while the switching element 27 of the individual section IV is opened and the switching element 31 between the input E and the output A of the individual section IV is closed.

It can be seen that with the individual sections I to IV according to FIG. 3, the number of turns connected in sixteen steps of ten turns each can be changed from zero to one hundred and fifty. Each step corresponds to a certain change in the magnitude of the voltage to be reduced.

If the nominal voltage Ul is, for example, 220 V, the voltage U2 to be taken off in all the four individual sections I to IV connected to z. B. 210 V and the voltage to be decreased U2 in all four switched off sections I to IV, so only with the turns of the second part 19 of the control section 17 z. B. is 170 V, the voltage U2 can thus be changed between 170 V and 210 V in sixteen steps. However, the change in voltage at the individual stages is not the same. This means that there is no linearity between the number of turns connected and the change in the magnitude of the voltage U2 to be reduced.

The relationship between the number of turns NR connected and the voltage U2 to be taken off results from the following formula

NL x U2

NR = - NF (I)

(U1-U2)

where NL is the number of turns of the load section 4, Ul is the nominal voltage and NF is the unchangeable number of turns of the second part 19 of the control section 17.

Based on the formula (I) it was calculated that, for example with six individual sections I to VI, the voltage U2 to be taken can be changed linearly in approximately 5 V steps at a nominal voltage of 220 V from 120 V to 205 V if two turns in the individual section I , five turns in section II, eleven turns in section III, twenty-four turns in section IV and fifty-four or one hundred and three turns in section V or VI are provided. In lighting systems, however, a linear increase and decrease in U2 is often not necessary, sometimes even undesirable. The entire effective winding, ie the load section 4, the second part 19 of the control section 17 with the invariable number of turns NF and the connected turns NR of the first part 18 of the control section 17 form the primary winding of the economy transformer, while the second part 19 and the connected turns NR of the first part 18 form the secondary winding. It can be seen that the primary and secondary windings can be changed in the economy transformer, depending on which individual sections I to IV are interconnected and connected to the neutral conductor N.

The transformer can also be designed in three phases.

If the first switching element 24 to 27 and the second switching element 28 to 31 of the individual sections I to IV are closed simultaneously according to FIG. 3, the relevant individual section I to IV is short-circuited, so that it can be destroyed. Contactors, that is, remote-controlled electromagnetic switches, can be used as switching elements 24 to 31, which are inexpensive and can withstand millions of switching operations.

When using contactors as switching elements 24 to 31, a brief interruption of the magnetizing current IM is inevitable. During the changeover time, that is to say this brief interruption of, for example, a few milliseconds, the load section 4 acts as a choke for the lamp 6. As a result, a voltage is applied to the lamp 6 during the changeover time, which the Nominal voltage Ul minus the load voltage UL corresponds. This means if, for example, the nominal voltage is 220 V and the load voltage is 5 V, and thus a voltage of 215 V is applied to the lamp 6 when switching with a contactor. There may be a brief twitch of the light.

The two switching elements 24 and 28, 25 and 29, 26 and 30 and 27 and 31 of each individual section I to IV should therefore switch on the one hand at the same time, if possible, so that the twitching is eliminated, and on the other hand they must not be closed at the same time, because otherwise a short circuit occurs.

The short-circuit current, however, takes a certain time, e.g. B. two to ten milliseconds until it builds up fully. Therefore, if switching elements 24 to 31 are used which have a very short switchover time, for example a switchover time which is half or less the set-up time for the short-circuit current, there is a risk that a short-circuit will damage the individual sections I to IV concerned, significantly reduced.

The cheaper commercially available contactors can therefore be used without further ado if the current peaks mentioned are accepted when switching, which are manifested by a brief twitching of the light from the lamp 6. However, the cheaper contactors can no longer be used if the switches 24 and 28, 25 and 29, 26 and 30 and 27 and 31 of the individual sections I to IV are actuated simultaneously, even if 146 ₁₈ PCI7EP96 / 00428

if the switchover time of the contactors is shorter than the build-up time of the short-circuit current.

To remedy this, either larger contactors can be used or a resistor or a choke can be arranged in the current path of the individual sections I to IV at any point, for example in the lines 36 to 39, which for the individual section I in FIG resistor 43 is shown in line 36. The short-circuit current is limited accordingly for a short time by the resistor or the choke. Furthermore, a transformer fire in the event of incorrect switching can be prevented by a fuse (not shown) in series with the choke 43.

In the transformer according to FIG. 4, the primary winding 12 is constructed from individual sections I to IV in the same way as the first part 18 of the control section 17 of the energy-saving transformer according to FIG. 3. Accordingly, the same reference numbers for the switching elements 24 to 31 are also shown in FIG. lines 32 to 39 and resistor 43 are used. The switching element 11 is arranged in the line 16, which connects the output of the individual section IV to the neutral conductor N. Through lines 15 and 16, this transformer is also connected as an economy transformer.

In the embodiment according to FIG. 5, the control section 17 of the economy transformer has a plurality of branches 53, 54, 55, which are switched by the switching elements 50, 51, 52, preferably contactors, optionally connectable to the neutral line N.

Claims

claims

1. Device for uninterrupted

Voltage control with an autotransformer, characterized by at least one switching element (11; 24 to 31; 50, 51, 52) in the primary circuit (2, 12) for decommissioning the transformer function and at least one further switching element (9, 24 to 31; 50, 51, 52) in the primary circuit (2, 12) or parallel to the load section (4, 13) of the transformer, the switching elements (9, 11; 24 to 31) being controlled in this way when switching over to change the voltage (U2) on the consumer (6) are that the load section (4, 13) forms a throttle.

2. Device according to claim 1, characterized in that the switching elements (9, 11; 24 to 31; 50 to 52) are formed by a contactor.

3. Apparatus according to claim 1 or 2, characterized in that the primary and / or secondary winding (2, 12; 17, 13) at least partially consists of individual sections (I to IV) which in one of the voltage (U2) on the Consumer (6) corresponding combination can be interconnected are .

4. The device according to claim 3, characterized in that at least one individual section (I to IV) is provided, which has a first switching element (24 to 27) in its current path and a further switching element between its input (E) and its output (A) (28 to 31).

5. Device according to one of the preceding claims, characterized in that each individual section (I to IV) has a resistor, a choke (43) and / or a fuse.

6. Device according to one of the preceding claims, characterized in that the

Transformer winding of the autotransformer has a load section (4) connected on the input side to the phase (L) of the network and on the output side to the phase of the consumer (6) and a control section (17) connected on the output side to the neutral conductor (N), which control section (17) consists at least partially of the individual sections (I to IV), which can be connected in a combination corresponding to the voltage (U2) to the consumer (6) with the neutral conductor (N).

7. The device according to claim 6, characterized in that the control section (17) consists of a first part (18) and a second part (19) between the first part (18) and the load section (4), the number of with the neutral conductor (N) connected turns of the second part (19) unchangeable and the number of neutral

(N) changeable turns of the first part (18) is changeable.

8. Use of the device according to one of the preceding claims for controlling a lighting system.

9. Use of the device according to one of claims 1 to 7 for power control of a consumer or a consumer group.

10. Use of the device according to one of claims 1 to 7 for voltage compensation in electrical systems.

CHANGED REQUIREMENTS

[Received at the International Office on July 17, 1996 (July 17, 1996), original claims 8-10 deleted; original 1 changed; all other claims unchanged (2 pages)]

Device for uninterrupted voltage regulation of a lighting system with an autotransformer, characterized by at least one switching element (11; 24 to 31; 50, 51, 52) in the primary circuit (2, 12) for decommissioning the transformer function and at least one further switching element (9, 24 to 31 ; 50, 51 52) in the primary circuit (2, 12) or parallel to the load section (4, 13) of the transformer, the switching elements (9, 11; 24 to. When switching over to change the voltage (TJ2) on the consumer (6) 31) are controlled so that the load section (4, 13) forms a throttle.

Device according to claim 1, characterized in that the switching elements (9, 11; 24 to 31; 50 to 52) are formed by a contactor.

Apparatus according to claim 1 or 2, characterized in that the primary and / or secondary winding (2, 12; 17, 13) at least partially consists of individual sections (I to IV) which are in one of the voltage (U2) on the consumer ( 6) connect the corresponding combination (N) connected turns of the second part (19) cannot be changed and the number of turns of the first part (18) which can be changed with the neutral conductor (N) can be changed.