RU2846345C1 - Wind-driven power plant voltage and frequency stabilization device - Google Patents

Abstract

FIELD: renewable power engineering.

SUBSTANCE: invention relates to renewable power engineering, particularly to conversion of wind energy. Device for stabilizing the voltage and frequency of a wind power plant comprises windwheel 5 connected to multiplier 6, output shaft of which is connected to rotor of synchronous generator with permanent magnets 1, uncontrolled rectifier 7, single-phase bridge inverter 2 power circuit containing single-phase bridge inverter 8 capacitor, single-phase bridge inverter first, second, third and fourth transistors 9-12, respectively, first, second, third and fourth reverse diodes of single-phase bridge inverter 13-16, respectively, filter 17, single-phase-three-phase transformer with rotating magnetic field 3 comprising first and second primary windings of transformer with rotating magnetic field 18 and 19, respectively, phase-shifting capacitor 23, the first, the second and the third secondary windings of transformer with rotary magnetic field 20-22 respectively. Outputs A, B, C and N serve for load connection. Inverter 4 control unit comprises: transformer-rectifier unit 24, rectifier of control unit 25, sinusoidal voltage generator 26, pulse generator 27, saw-tooth voltage generator 28, adder 29, voltage divider 30, voltage polarity sensor 31, first and second AND logic elements 32 and 33, respectively and first and second pulse amplifiers 34 and 35, respectively.

EFFECT: higher efficiency and reliability of the device, as well as faster operation of the control system for stabilizing voltage and frequency.

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Description

The invention relates to electric power engineering, in particular to the conversion of wind energy into electrical energy with stable parameters of output voltage and frequency.

The known device (RU Patent No. 2225531, F03D 7/04, Bulletin No. 7, 2004) consists of an asynchronous multi-speed generator, a switching unit, a voltage stabilization device, excitation capacitors and additional capacitors, an electromagnetic clutch and a frequency stabilization system.

The disadvantages of the device are low efficiency and reliability, large mass and dimensions of the electrical part.

The closest in technical solution is a device (RU Patent No. 2443903, F03D 9/00, Bulletin No. 6, 2012), consisting of a wind wheel, a multiplier (speed reducer), an electromagnetic clutch and a synchronous generator with permanent magnets with a magnetization winding, located on one shaft, a block of excitation capacitors, a voltage stabilization block and a frequency stabilization block.

The disadvantages of the device are low efficiency and reliability, as well as low response time of the control system for stabilizing voltage and frequency.

The technical solution of the proposed invention is to increase the efficiency, reliability of the device and the speed of the control system for stabilizing voltage and frequency.

The technical solution is achieved in that the device for stabilizing the voltage and frequency of a wind power plant, containing a wind wheel, a multiplier, a synchronous generator with permanent magnets, located on the same shaft, according to the invention has an uncontrolled rectifier, a single-phase bridge inverter, a filter, a single-phase-three-phase transformer with a rotating magnetic field and an inverter control unit, wherein the wind wheel is connected via the multiplier to the input of the synchronous generator with permanent magnets, the output of which is connected via the first and second outputs of the rectifier and the capacitor to the first and second input of the power circuit of the single-phase bridge inverter, the control inputs of the first, second, third and fourth transistors of which are connected to the outputs of the inverter control unit, the collectors of the first and third transistors are connected to each other and connected to the first output of the uncontrolled rectifier, the second output of which is connected to the emitters of the second and third transistors, which are connected to each other, the emitter of the first transistor is connected to the collector of the second transistor and are connected via the filter with the beginning of the first primary windings of a single-phase-three-phase transformer with a rotating magnetic field, the ends of these windings are connected through a filter to the emitter of the third and the collector of the fourth transistors, which are connected to each other, reverse diodes are turned off in opposite parallel to the emitter-collector junction of the inverter transistors, the first and second outputs of the single-phase bridge inverter are connected through a filter to the inputs of the first and second primary windings, located on the toroidal part of the single-phase-three-phase transformer with a rotating magnetic field and which are shifted in space relative to each other at an angle of 90°, and their beginnings are connected to each other through a phase-shifting capacitor, three secondary windings of the transformer are shifted relative to each other at an angle of 120°, also located on the toroidal part of the single-phase-three-phase transformer with a rotating magnetic field, and a load is connected to their terminals A, B, C and N, the inverter control unit contains a transformer-rectifier unit, a control unit rectifier, a sinusoidal voltage generator, a pulse former, a sawtooth voltage generator, an adder, a voltage divider, a voltage polarity sensor, first and second AND logical elements, first and second pulse amplifiers, wherein the first and second inputs of the voltage divider are connected to the first and second outputs of the uncontrolled rectifier, and the output of the voltage divider is connected to the first input of the adder, the second input of which is connected via the transformer-rectifier unit to the terminals of the device A, B, C and N, the output of the adder is connected via the sawtooth voltage generator to the first input of the pulse former, the second input of which is connected via the control unit rectifier to the sinusoidal voltage generator, the output of the pulse former is connected to the first inputs of the first and second AND logical elements, respectively, the second inputs of which are connected via the voltage polarity sensor to the sinusoidal voltage generator, the outputs of the first and second AND logical elements, respectively, are connected via the first and second pulse amplifiers to the control inputs of the transistors of the single-phase bridge inverter circuits, where the output of the first pulse amplifier is connected to the control inputs of the first and fourth transistors, and the output of the second pulse amplifier is connected to the control inputs of the second and third transistors.

The novelty of the claimed proposal is due to the fact that due to the use of an uncontrolled rectifier at the generator output, voltage and frequency stabilization carried out by a single-phase bridge circuit of the inverter, where a triangular signal is used as a reference signal, and a direct current voltage proportional to the sum of the voltages at the rectifier output and at the output of the stabilization device is used as a leading signal, while the three-phase voltage system is formed by a single-phase-three-phase transformer with a rotating magnetic field, a technical result is achieved, which consists in increasing the efficiency, reliability of the device and the speed of the control system for stabilizing voltage and frequency.

According to scientific, technical and patent literature, the authors are not aware of the claimed set of features aimed at achieving a technical solution, and this solution does not obviously follow from the known level of technology, which allows us to conclude that the solution complies with the inventive step.

The essence of the invention is explained by the drawings, where Fig. 1 shows a functional diagram of the voltage and frequency stabilization device of the wind power plant, and Fig. 2 shows voltage diagrams explaining the operating principle of the control system for stabilizing the voltage and frequency of the wind power plant, in a) - a diagram of the voltages of the reference signal u _PN1 , the leading signal u _B2 and the total voltage u _{∑ 1} = u _DN +u _TVB of the voltage divider DN and the transformer-rectifier unit TVB; in b) - control pulses u _U1 and u _Uy , forming the positive and negative half-waves of the inverter output voltage u _ab1 , respectively; in c) - the waveform of the voltage at the output of the voltage polarity sensor DPN; in d) - a diagram of the voltages of the reference signal u _PN2 , the leading signal u _B2 and the total voltage u _{∑ 2} = u _DN +u _TVB of the voltage divider DN and the transformer-rectifier unit TVB; on d) - control pulses u _У1 and u _Уу , forming the positive and negative half-waves of the inverter output voltage u _аб2 , respectively.

The wind turbine voltage and frequency stabilization device has elements under the following positions:

1 - synchronous generator with permanent magnets;

2 - power circuit of a single-phase bridge inverter;

3 - single-phase-three-phase transformer with rotating magnetic field;

4 - inverter control unit;

5 - wind wheel;

6 - multiplier (speed reducer);

7 - uncontrolled rectifier;

8 - capacitor of single-phase bridge inverter;

9 - the first transistor of the single-phase bridge inverter;

10 - the second transistor of the single-phase bridge inverter;

11 - the third transistor of the single-phase bridge inverter;

12 - the fourth transistor of the single-phase bridge inverter;

13 - first reverse diode of single-phase bridge inverter;

14 - the second reverse diode of the single-phase bridge inverter;

15 - the third reverse diode of the single-phase bridge inverter;

16 - the fourth reverse diode of the single-phase bridge inverter;

17 - filter;

18 - first primary winding of a transformer with a rotating magnetic field;

19 - the second primary winding of the transformer with a rotating magnetic field;

20 - the first secondary winding of the transformer with a rotating magnetic field;

21 - the second secondary winding of the transformer with a rotating magnetic field;

22 - the third secondary winding of the transformer with a rotating magnetic field;

23 - phase-shifting capacitor;

24 - transformer-rectifier unit;

25 - control unit rectifier;

26 - sinusoidal voltage generator;

27 - pulse generator;

28 - sawtooth voltage generator;

29 - adder;

30 - voltage divider;

31 - voltage polarity sensor;

32 - first logical AND element;

33 - the second logical element AND;

34 - first pulse amplifier;

35 - second pulse amplifier;

A, B, C and N are terminals for connecting the load.

The device for stabilizing the voltage and frequency of a wind power plant has a wind wheel 5 connected to a multiplier (speed reducer) 6, the output shaft of which is connected to the rotor of a synchronous generator with permanent magnets 1, an uncontrolled rectifier 7, a power circuit of a single-phase bridge inverter 2, containing a capacitor of a single-phase bridge inverter 8, the first, second, third and fourth transistors of a single-phase bridge inverter 9-12, respectively, the first, second, third and fourth reverse diodes of a single-phase bridge inverter 13-16, respectively, a filter 17, a single-phase-three-phase transformer with a rotating magnetic field 3, containing the first and second primary windings of a transformer with a rotating magnetic field 18 and 19, respectively, a phase-shifting capacitor 23, the first, second and third secondary windings of a transformer with a rotating magnetic field 20-22, respectively. Terminals A, B, C and N are used to connect the load, inverter control unit 4, containing transformer-rectifier unit 24, control unit rectifier 25, sinusoidal voltage generator 26, pulse former 27, sawtooth voltage generator 28, adder 29, voltage divider 30, voltage polarity sensor 31, first and second AND logical elements 32 and 33 respectively and first and second pulse amplifiers 34 and 35 respectively.

The device for stabilizing the voltage and frequency of the wind power plant operates as follows. The multiplier (speed reducer) 6 increases the rotation frequency of the wind wheel 5 from n ₁ to n ₂ (Fig. 1), the output shaft of which is connected to the rotor of the synchronous generator with permanent magnets 1. The generator is excited by the magnetic flux created by the permanent magnets. The generator terminals are connected to the uncontrolled rectifier 7, which converts the three-phase AC voltage system into DC voltage. The DC voltage is converted by the power circuit of the single-phase bridge inverter 2 into a single-phase AC voltage, which is converted by the single-phase-three-phase transformer with a rotating magnetic field 3 into a three-phase symmetrical voltage system.

The inverter control unit 4 operates as follows. The voltage from the output of the uncontrolled rectifier 7 is applied to the input of the voltage divider 30 of the inverter control unit 4 (Fig. 1), the signal from the output of whichu _DN goes to the first input of adder 29, to the second input of which the signal goesu _TVB with the output of the transformer-rectifier unit 24, the input of which is connected to the output terminals of the device A, B and C. The output voltage of the adder 29u _{∑ 1} = u _{DN 1} +u _TVB is applied to the input of the sawtooth voltage generator 28, at the output of which a reference sawtooth signal is formedu _{Mon 1} , this signal is fed to the first input of pulse generator 27, to the second input of which the leading signal is fedu _B2 from rectifier 25, which is synchronized with the signalu _SN , sinusoidal voltage generator 26 (Fig. 2, a, b). Whenu _PN1 <u _B2 at the output of pulse generator 27, control signals are generated by means of PWM (pulse width modulation)u _U (Fig. 2, b), which are fed to the first inputs of the first and second logical elements AND 32 and 33, respectively, and a signal about the voltage polarity is fed to the second inputs of these elements.u _DPN from the voltage polarity sensor DPN, the operation of which is synchronized with the sinusoidal voltage generator 26 with its positive polarityu _PP and with its negative polarityu _OP respectively (Fig. 2, b, c). As a result, the control pulsesu _U are fed to the control electrodes of the first and fourth transistors 9 and 12 of the single-phase bridge inverter, respectively, when a positive half-wave of voltage is formed at its outputu _{A b 1} and to the second and third transistors of the single-phase bridge inverter 10 and 11, respectively, when forming the negative half-wave of the inverter output voltageu _{A b 1} (Fig. 2, b), which is transformed by a transformer with a rotating magnetic field 3 into a three-phase symmetrical voltage system.

Regardless of the rotation frequency of the wind wheel 5, at the output of the power circuit of the single-phase bridge inverter 2, the frequency of the sinusoidal current voltage does not change, and it will correspond to the frequency of the sinusoidal voltage master generator 26 of the inverter control unit 4 (Fig. 1).

The principle of operation of the inverter control unit 4 for voltage stabilization. For example, if the voltage at the output of the uncontrolled rectifier 7 decreases (Fig. 1), then the voltage at the output of the power circuit of the single-phase bridge inverter 2 u _{П Н2} decreases, and this will lead to a decrease in the voltage u _{∑ 2} at the output of the adder 29 (Fig. 2, г). As a result, the duration of the control pulses u _У will increase and the amplitude value of the voltage at the output of the power circuit of the single-phase bridge inverter 2 will increase u _{ab 2} > u _{ab 1} (Fig. 2, б, д), i.e. automatic stabilization of the voltage at the output of the power circuit of the single-phase bridge inverter 2 will occur.

Changes in voltage at terminals A, B and C of the device (Fig. 1) will lead to a change in the voltage valueu _TVB at the output of the transformer-rectifier unit 24 and the total voltage valueu _∑ at the output of the adder 29, respectively, and this will also lead to a change in the duration of the control pulsesu _U (Fig. 2), as a result, the inverter control unit system 4 automatically stabilizes the voltage to the nominal value level.

Thus, regardless of the rotation frequency of the wind wheel and the destabilizing factors arising in the load at terminals A, B and C, the inverter control unit 4 automatically stabilizes the magnitude and frequency of the wind power plant voltage.

The use of a rectifier, a single-phase inverter, a single-phase-three-phase transformer with a rotating magnetic field and the proposed inverter control unit in the converter, where a sawtooth signal is used as a reference signal, and a direct current voltage proportional to the sum of the voltages at the output of the uncontrolled rectifier and at the output of the device is used as a leading signal, favorably distinguishes the proposed device for stabilizing the voltage and frequency of a wind power plant from the known one, since the efficiency is improved, the reliability of the device and the speed of the control system for stabilizing the voltage and its frequency are increased.

The study was carried out with the financial support of the Kuban Science Foundation within the framework of scientific project No. MFI-20.1/27.

Claims (1)

A device for stabilizing the voltage and frequency of a wind power plant, comprising a wind wheel, a multiplier, a synchronous generator with permanent magnets, located on the same shaft, characterized in that it has an uncontrolled rectifier, a single-phase bridge inverter, a filter, a single-phase-three-phase transformer with a rotating magnetic field and an inverter control unit, wherein the wind wheel is connected via the multiplier to the input of the synchronous generator with permanent magnets, the output of which is connected via the first and second outputs of the rectifier and a capacitor to the first and second inputs of the power circuit of the single-phase bridge inverter, the control inputs of the first, second, third and fourth transistors of which are connected to the outputs of the inverter control unit, the collectors of the first and third transistors are connected to each other and connected to the first output of the uncontrolled rectifier, the second output of which is connected to the emitters of the second and third transistors, connected to each other, the emitter of the first transistor is connected to the collector of the second transistor and are connected through a filter with the beginning of the first primary windings of a single-phase-three-phase transformer with a rotating magnetic field, the ends of these windings are connected through a filter to the emitter of the third and the collector of the fourth transistors, which are connected to each other, reverse diodes are turned off in opposite parallel to the emitter-collector junction of the inverter transistors, the first and second outputs of the single-phase bridge inverter are connected through a filter to the inputs of the first and second primary windings, located on the toroidal part of the single-phase-three-phase transformer with a rotating magnetic field and shifted in space relative to each other at an angle of 90 °, and their beginnings are connected to each other through a phase-shifting capacitor, three secondary windings of the transformer are shifted relative to each other at an angle of 120 °, also located on the toroidal part of the single-phase-three-phase transformer with a rotating magnetic field and a load is connected to their terminals A, B, C and N, the inverter control unit comprises a transformer-rectifier unit, a control unit rectifier, a sinusoidal voltage generator, a pulse former, a sawtooth voltage generator, an adder, a voltage divider, a voltage polarity sensor, first and second AND logic elements, first and second pulse amplifiers, wherein the first and second inputs of the voltage divider are connected to the first and second outputs of the uncontrolled rectifier, and the output of the voltage divider is connected to the first input of the adder, the second input of which is connected via the transformer-rectifier unit to the terminals of the device A, B, C and N, the output of the adder is connected via the sawtooth voltage generator to the first input of the pulse former, the second input of which is connected via the control unit rectifier to the sinusoidal voltage generator, the output of the pulse former is connected to the first inputs of the first and second AND logic elements, respectively, the second inputs of which are connected via the voltage polarity sensor to the sinusoidal voltage generator, the outputs of the first and second AND logic elements, respectively, are connected via the first and second pulse amplifiers to the control inputs of the transistors of the single-phase bridge circuit of inverters, wherein the output of the first pulse amplifier is connected to the control inputs of the first and fourth transistors, and the output of the second pulse amplifier is connected to the control inputs of the second and third transistors.