FI120991B - Method and apparatus for regulating mains voltage - Google Patents

Description

FIELD OF THE INVENTION 5 The aim is to design and dimension power transmission networks so that the electricity received by consumers is of sufficiently good quality and yet the transmission network costs are low. However, there are often problems such as long distances from substations to substations to customers and very high transient loads. This causes a relatively large momentary voltage drop in the long transmission lines, i.e., a voltage drop, for example, when starting an electric motor when welding or chopping trees with a flapper. Voltages like this are quite embarrassing because they often appear as flickering lights. At worst, they may cause the electrical equipment to shut down and / or restart. An electronic device can fail up to 15 if it is not protected against such undervoltage.

High electricity consumption, for example in severe frost, can also cause an estimated significant voltage drop in peak load situations. In this case, the voltage may be below the permissible voltage level for extended periods of time, for example, below 207 20 V.

Prior art

Several methods have been developed to improve the quality of the mains voltage. The conventional autotransformer, shown in Figure 1, is known to be used to reduce or increase the bandwidth, as shown in Figure 1. The advantage of such a power transformer over the transformer is that it can be sized significantly smaller than the transformer. For example, if a 10% increase in voltage is required, the power transformer can be built much smaller than 30, since it handles only 10% of the power consumed by the load, and 90% of the power comes directly from the grid, 2 the transformer must always transfer all power itself from the input side to the output side.

However, simply raising or lowering the voltage does not permanently help with flicker problems, and not always with undervoltage or overvoltage problems. To improve the quality of electricity, the power transformer must be active and adjust the amount of voltage increase or reduction to compensate for network disturbances.

Indeed, the Norwegian company Magtech AS has developed such an adjustable device 10, based on the principle of a power transformer (WO 2007/035110 AI). In the device according to this patent application, the output voltage is controlled by changing the inductance of a separate DC-impregnated choke. The choke to be added is connected in series with the primary transformer winding.

15

Because it takes time to change the degree of saturation of the inductor, there is a delay in responding to a rapid voltage change (response time 150-300 ms). Thus, the method is far too slow to compensate for flicker caused by rapid (less than 20 ms) voltage fluctuations. Instead, such a method tends to add a crack to the mains voltage. It is also very heavy and causes a lot of power loss. The implementation of a prior art transformer is also expensive. Because of its slowness, the device poses a risk of overvoltage to the output and hence of equipment connected thereto. For example, if the input voltage has been 190 V for a long time, for example longer than 300 ms, the device has increased the output voltage to about 232 V. If the voltage supplied to the device now rises rapidly, for example, to a nominal value of 230 V, the voltage supplied by the device will also rise in the same proportion to about 278 V, making it even longer than 150 ms.

30 For example, varistors protect against transient voltages in power networks. Generally, a 230V AC device typically uses 275V varistors. However, varistors work well 3 only for limiting transient transient voltages due to their low energy tolerance.

BRIEF DESCRIPTION OF THE INVENTION 5

The invention advantageously provides a device based on a power transformer and stepwise controlled by switching components for generating high-quality mains electricity. This device can also be brought close to the consumer of electricity because of its small size. This is obtained by a method for generating a mains voltage with a power transformer. The method adjusts the mains voltage to the desired value by using switches SI and S4 series n connected to each other and using at least one primary winding Npri_l by using a switch SI in parallel with the primary winding Npri_l to connect to the open and closed states of the first na-15min. In series with Npri_1 for switching to open and closed states relative to the other terminal of the voltage source, measuring the line voltage level and controlling said two switches S1 and S4 to the open and closed states to generate the desired level output voltage across the secondary winding Nsec.

The invention also saving transformer comprising a primary side, the primary side and brought to form a network voltage. To adjust its output voltage to the desired value, the transformer comprises at least one primary winding 25 Npri_l and a series of switches S1 and S4 coupled to each other arranged such that the switch S1 is parallel to the the open and closed states of the voltage source relative to the second terminal, and a control arrangement of the mains voltage 30 for measuring the level of said at least two switches SI and S4 are measured for controlling the supply voltage on the basis of the level of the open and closed conditions to form a desired level 4 swampy secondary side of the mains voltage via the secondary winding nsec.

The invention is based on a switch arrangement arranged with the primary windings 5 in series and parallel connections, and the switches are controlled to open and closed positions using a control arrangement which follows the level of the mains voltage to the primary or secondary side of the transformer. The control of the switches by means of a control arrangement to an open state or a non-conductive state and a closed state, i.e. a conductive state, is performed based on the measured voltage of the line voltage or otherwise based on a reference voltage or voltage waveform.

The power transformer according to the invention compensates successfully and, if necessary, quickly for unevenness in the mains voltage, i.e. voltage surges and downs, preventing the mains voltage flicker. According to the invention, both overvoltage and undervoltage protection, fast and long-term voltage level control and voltage waveform shaping can be implemented. In addition, the manufacturing cost of the energy-saving transformer according to the invention is advantageous compared to the prior art implementation, thus enabling the energy-saving transformer of the invention to be more readily available for its potential applications, for example, in sparsely populated areas.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 shows a transformer circuit according to the prior art.

Fig. 2 shows a power transformer according to the invention for controlling the mains voltage. 1

Figure 3 shows as a voltage curve what happens to a sinusoidal mains voltage in the correction control according to the invention.

5

Fig. 4 shows a power transformer according to a first preferred embodiment of the invention for controlling the mains voltage.

Figure 5 shows a line voltage control curve according to a first preferred embodiment of the invention.

Fig. 6 shows a power transformer according to another preferred embodiment of the invention for controlling the mains voltage.

Fig. 7 shows embodiments according to preferred embodiments of the invention for three-phase control of the mains voltage.

DETAILED DESCRIPTION OF THE INVENTION The long distance transmission of electrical energy from a power generating power plant to an end user, such as a household, is accomplished by high-voltage power lines that supply three-phase alternating current, such as 22 kV. Converters from high-voltage AC to low-20, for example 230V AC, or end-user mains voltage, are implemented with transformers. Before transmitting the mains voltage to the user's needs, it is controlled by an automatically adjustable power transformer to ensure that the level and quality of mains voltage is suitable for the equipment and machines using it. In an urban area, this can be accomplished for 25 multiple households with the same auto-adjusting savings transformer. For sparsely populated rural farms or, for example, summer cottages, this conversion can be implemented with a farm-or-cottage-specific, auto-adjusting savings transformer. To accomplish these objectives, the present invention provides a solution by enabling the implementation of a high-voltage, low-cost, auto-adjustable power transformer.

6

Fig. 2 shows a power transformer according to the invention for controlling the mains voltage. In the method according to the invention, using the control arrangement, the mains voltage to the primary or secondary side of the savings transformer is measured, either its average or effective value, and the primary transformer coil 5 Npri_l is always selected so as to adjust the supply voltage to the desired voltage across the output transformer. Figure 2 shows an implementation measuring the mains voltage to the primary side. At least two switches (S1, S4) and at least one primary winding (Npri_1) are always used in the auxiliary transformer according to the invention such that the switch 10 S1 is parallel to the primary winding Npri_1 and the switch S4 switches the primary winding Npri_1 to another terminal such as a neutral.

Figure 3 shows as a voltage curve what happens to the voltage in the correction control according to the invention based on the measurable input or load 15 mains voltage and the controlled switch states. More specifically, Figure 3 also shows the time period measuring the mains voltage at which the switch control is performed and how the switch state changes occur in accordance with the control. The power transformer quickly corrects the mains voltage, for example, with a delay of less than 10 ms. The implementation according to the invention is also advantageous because the switching of the switches can be timed to the peak value of the voltage to be measured, whereby the excitation current of the saving transformer is at its lowest. In this way, the RC circuits connected to the switches can be dimensioned as small as possible.

The implementation according to the invention is also advantageous because it has the ability to react to fast network overvoltages, for example less than 100 microseconds. If the instantaneous value of the mains voltage, for example, exceeds 350 V (equivalent to about 250 VAC) when the transformer is in a voltage boosting mode, it immediately switches to a mode where the auxiliary transformer 30 has no effect on the mains voltage. This feature prevents hardware failures caused by network surges.

7

The saving transformer according to the first preferred embodiment of the invention shown in Fig. 4 provides a voltage-boosting control of the mains voltage so that the primary side has three windings (Npri_1, Npri_2, Npri_3) and 4 switches (S4, S3, S2 and SI). The switch S1 adjacent to the En-5 core winding (Npri_1) plays an important role in the realization of the objects of the invention as set forth below. It is essential for the invention that at least one of the primary windings (Npri_1, Npri_2, Npri_3) has a switch S1 connected in parallel. Thus, the embodiment of the invention is not limited to that shown in Figure 4, but the stiffness of the couplings may be different.

The device according to the first preferred embodiment of the invention provides a four-stage auxiliary voltage to the AC output voltage output from the transformer, e.g. between 209 -222 V, the third control stage has an auxiliary voltage effect of + 13.4% when the incoming phase voltage is between 197 and 209 V and the fourth control stage an auxiliary voltage effect of + 20% when the incoming phase voltage is less than 197 V.

For example, by selecting the device's voltage boost capability (B) at 20% from the following formula, where the auxiliary voltage effect B = 20%, it can be calculated that: 25 Vini = (1- (Β / 2) / 3) χ230 V = 222.3 V, below 222.3 V, switch S2 is connected to a conductive state, whereby the voltage output from the auxiliary transformer rises to the value calculated in the following formula when B = 20%: 30

Vouti = (l + B / 3) x (1-Β / 6) χ230 V = (1 + B / 6-B2 / 18) x230 V = 237.2 V.

8

For example, if the mains voltage exceeds 222 V, the output voltage will not be raised by the device. Then the switch SI is closed. It prevents the dormant sleeper from operating in an inverse manner, whereby the secondary winding Nsec acts as a primary winding and the primary windings as a secondary winding. The voltages of the switches S2, S3 and S4 would then be very high, which would be a very difficult situation for the switch elements in question. The most difficult situation would be at the time of connection to the mains, where, for example, under capacitive load, the entire mains voltage would remain above the secondary winding Nsec. The embodiments of the invention prevent such situations.

In a first preferred embodiment of the invention, the current of the switch S1 is IS1 = B * I | oad + Imag, where I | 0ad is the load current, the Imag auxiliary transformer magnetizing current 15 and B an additional voltage effect.

If, for example, the phase-to-phase voltage of the AC input voltage to the power transformer continues to fall below:

20 Vin2 = Vini / (l + 2B / 3) = [(l + B / 3) x (l-B / 6) / (l + 2B / 3)] x230 V = 209.3 V

, when B = 20%, open switch S2 and close switch S3. The output voltage then increases from 209.3 V to 25 Vout2 = (l + 2B / 3) x209.3 V = 237.2 V.

For example, if the incoming voltage drops below this value:

Vin3 = Vin2 / (1 + B) = [(1 + B / 3) x (1 -B / 6) / (1 + B)] x230V = 197.6V, open switch S3 and connect switch S4. The output voltage then rises to 9

Vout3 = (l + B) xVin = 237.2 V.

In a first preferred embodiment of the invention, the mains voltage could drop to 172.5 V, for example, before the outputs reach a limit of 207 5 V, which is a lower limit for mains voltage as defined in the international standard (EN 50160).

Fig. 5 shows a four-stage line voltage control curve according to a first preferred embodiment of the invention, shown by a solid line. The Kat-10 diatribe shows what would happen to the mains voltage in this example without adjustment.

Fig. 6 shows a saving transformer according to another preferred embodiment of the invention, which also provides a voltage reduction of the mains voltage by effect, for example in the range of 0-20% reduction effect. It includes four switches S5, S6, S7 and S8, of which the switches S5 and S8, and S6 and S7 are arranged in pairs to operate simultaneously. With the coupling pair S5 and S8 closed, the coupling pair S6 and S7 are respectively open and vice versa. In this way, the polarity or direction of the primary winding Npri_l can be changed to 20 secondary windings relative to Nsec. In this way, when the switch pair S5 and S8 are closed, the output voltage is increased and, when the switch pair S6 and S7 are closed, the output voltage is lowered.

An output voltage reduction embodiment according to another preferred embodiment of the invention may also be used for overvoltage protection. The voltage-lowering embodiment shown in Fig. 6 causes the drive to operate, for example, at a voltage of 330 V, which is dropped by the power transformer according to the invention to about 265 V. According to the operation of the electronics of the said transformer, the output voltage in the case of an overvoltage can be reduced to a very high speed; up to less than 100 microseconds, thus providing effective overvoltage protection when used in conjunction with varistors.

10

In embodiments of the invention having more than one primary winding, a switch coupled to the primary winding may be located at different primary windings as well as a switch or switches of one hundred with one or more primary windings. The above preferred embodiments of the invention and the figures related thereto are thus exemplary, wherein the switch S1 is preferably located adjacent to the shortest and thickest primary winding Npri_1.

Fig. 7 illustrates embodiments 10 for controlling a mains voltage in three phases according to preferred embodiments of the invention. The three-phase implementation comprises three power transformer units that knock on the voltages of the various phases.

An embodiment of the invention may also provide a portable transformer, which combines a single-phase mains voltage with, for example, the need to operate a sensitive laboratory device. Similarly, for example, a portable "cottage model" may be implemented to clean up the voltage generated by the assembly for benign cottage equipment.

20 In practice, since there is always some stray inductance in the power transformer, each switch must be connected with an RC circuit, that is, a resistor and capacitor serial connection, thus reducing the voltage peaks generated by the spreading ductance.

In the embodiments of the invention described above, the auxiliary transformer comprises a control arrangement for monitoring the level of voltage to or from the primary side of the auxiliary transformer. The control arrangement comprises measuring electronics for monitoring the voltage level as well as switches and control logic electronics, i.e. a microcontroller, which, based on said monitoring, controls the switches in open states where the switches are nonconductive and in fixed states where the switches are conductive. The switches are implemented as switching transistors, for example bibolar transistors, IGBTs (Insulated Gate Bibolar Transistors) or most preferably FET electronics (Field Effect Transistors) such as MOSFETs or JFETs for implementing voltage-controlled switches according to the invention.

5

The energy transformer according to the invention can also be integrated with an electricity meter and electronics for measuring the quality of electricity. These can be integrated, for example, into a microcontroller, including the necessary display device and / or user interface.

10

Although the invention has been described above in the description with reference to the figures, the invention is not limited to the description and the figures, but may be modified within the scope of the appended claims.

Claims (12)

1. A method for generating mains voltage with a voltage transformer, characterized in that in the process the mains voltage is regulated to the desired value such that: - couplers S1 and S4 are used in series relative to each other, and at least one primary coil Npri_l is used. , that the coupler S1 is used in parallel with the primary coil Npri_l to be connected in open and closed positions relative to the first pole of the voltage source and the coupler S4 is used in series with the primary coil Npri_l to be connected in the open and closed positions relative to the second pole of the voltage source. level is measured, and 15. at the base of the measured mains voltage, said two couplers S1 and S4 are controlled in the open and closed positions to generate an output mains voltage of the desired level via the secondary coil Nsec. 2. A method according to claim 1, characterized in that three couplers S1, S2, S4 and two primary coils Npri_1, Npri_2 are used so that coupler S1 is used in parallel with the primary coil Npri_l for coupling in open and closed positions and couplers S2 and S4 are used. in series with the primary coil Npri_2 to be connected in open and closed positions. 1 2 3 4 5 6 Method according to claim 1, characterized in that four couplers 2 SI, S2, S3, S4 and three primary coils Npri_l, Npri_2, Npri_3 are used so that the 3 coupler S1 is used in parallel with the primary coil Npri_l to be coupled in 4 open and closed positions. , the couplers S3 and S4 are used in series with the primary coil Npri_2 for coupling in the open and closed positions and the couplers S2 and S3 6 are used in series with the primary coil Npri_3 for coupling in the open and closed positions. Method according to claim 1, characterized in that sealing couplers S1, S2, S3, S4, S5, S6, S7, S8 and three primary coils Npri_l, Npri_2, Npri_3 are used so that the coupler S1 is used in parallel with the primary coil Npri_l in the open and closed positions, the switches S3 and S4 are used in series 5 with the primary coil Npri_2 to be connected in the open and closed positions, the switches S2 and S3 are used in series with the primary coil Npri_3 to be connected in the open and closed positions and the switches S5 and S8 and S6 and S7 are arranged in pairs to operate simultaneously so that where the switches S5 and S8 are in the closed positions, the switches S6 and S7 are in the open positions to raise the level of the mains voltage and where the switches S6 and S7 are in the closed positions, the switches S5 and S8 are in the open positions. lowering the voltage level. 5 Npri_l switchable in open and closed positions and switches S2 and S4 are in series with the primary coil Npri_2 switchable in open and closed positions. 5. A method according to claim 1, characterized in that the highest level of the mains voltage is measured on the basis of which the switches are controlled. 15 Method according to claim 1, characterized in that the lowest level of the mains voltage is measured on the basis of which the switches are controlled. 7. A voltage transformer comprising a primary side and a secondary side for generating mains voltage, characterized in that the voltage transformer comprises for controlling its output voltage to the desired value: - at least one primary coil Npri_l and between the series switches S1 and S4 are connected in series, with the primary coil Npri_l switchable in open and closed positions relative to the first pole of the voltage source and coupler S4 are in series with the primary coil Npri_l switchable in open and closed positions relative to the second pole of the voltage source, and - a control arrangement for measuring the main voltage SI and S4 at the base of the measured mains voltage level in the open and closed positions for generating mains voltage with the desired level via the secondary side secondary coil Nsec. 8. A transformer according to claim 7, characterized in that the transformer comprises three couplers S1, S2, S4 and two primary coils Npri_l, Npri_2 so arranged that the coupler S1 is parallel to the primary coil. 9. A transformer according to claim 7, characterized in that the transformer comprises four couplers S1, S2, S3, S4 and three primary coils. 10. A transformer according to claim 7, characterized in that the transformer comprises light couplers S1, S2, S3, S4, S5, S6, S7, S8 and three primary coils Npri_l, Npri_2, Npri_3 arranged so that the coupler S1 is parallel to the primary coil. Npri_l switchable in the open and closed positions, the switches S3 and S4 are in series with the primary coil Npri_2 switchable in the open and closed positions and the switches S2 and S3 are in series with the primary coil Npri_3 switchable in the open and closed positions and the switches S5 and S6 and 57 are arranged in pairs to operate simultaneously so that where the switches S5 and 58 are in the closed positions, the switches S6 and S7 are in the open positions to raise the level of the mains voltage and where the switches S6 and S7 are in the closed positions the switches S5 and S8 in open positions to lower the near-voltage level. Npri_l, Npri_2, Npri_3 are arranged so that the coupler S1 is parallel to the primary coil Npr_l couplable in the open and closed positions, the couplers S3 and S4 are in series with the primary coil Npri_2 couplable in the open and closed positions and the couplers S2 and S3 are in series Npri_3 switchable in open and closed positions. 15 11. A transformer according to claim 7, characterized in that the transformer comprises a control arrangement for controlling the switches 30 at the base of the highest level measured from the mains voltage. 12. A transformer according to claim 7, characterized in that the transformer comprises a control arrangement for controlling the switches at the base of the lowest level measured from the mains voltage.