JP2008274882A - Hybrid wind power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid wind power generation system manufactured with a simple structure at low cost, and keeping constant outputting irrespective of change in wind speed. <P>SOLUTION: This system is provided with: a permanent magnet synchronous generator 12 mechanically connected to a shaft of a wind power turbine 10 and outputting electric power according to wind power; a thyristor rectifier 14 rectifying electric power output by the permanent magnet synchronous generator 12 and converting the same to direct current; a DC link part 16 supplying direct current smoothed based on electric power converted to direct current by the thyristor rectifier 14; a thyristor inverter 20 converting direct current supplied by the DC link part 16 to alternating current; a synchronous generator 24 driven by a motor 22 and outputting electric power; and a waveform improving reactor 26 composing alternating current electric power output by the thyristor inverter 20 and electric power output by the synchronous generator 24 and outputting predetermined electric power. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a hybrid wind power generation system capable of obtaining a constant output regardless of fluctuations in wind speed.

  In recent years, global warming and the depletion of natural resources due to large consumption of fossil fuels have become serious problems. The use of natural energy such as wind power is an effective solution to these problems.

  However, since the output of the wind power generation system fluctuates depending on the wind power as an energy source, there are many fluctuation factors due to the topography of the installation point, seasonal winds, etc., and it is unstable. For this reason, in order to operate a wind power generation system in conjunction with an existing power system, it is necessary to consider output fluctuations due to wind power generation. Conventionally, a wind power generation system often has a storage battery power source in order to reduce fluctuations in the output of the wind power generator. When sufficient wind power generation energy can be obtained, such a wind power generation system first charges the storage battery, detects surplus power, supplies power to the load, and wind power generation energy decreases. The battery output compensates for the decrease and provides stable power supply.

  Moreover, a hybrid power generation system using a solar power generation output and a wind power generation output has also been proposed (see, for example, Patent Document 1). The hybrid power generation system described in Patent Document 1 is a hybrid power generation system that is connected to an external power system via an orthogonal converter, and is a power output addition output by parallel connection of a solar power generator output and a wind power generator output. In response to changes in the natural environment, and also supports an operating state with only the output of solar power alone or wind power alone.

  This hybrid power generation system employs a control method as described below. First, when there is an output of solar power generation during the day, this hybrid power generation system makes a DC parallel connection in accordance with the output voltage of wind power generation in accordance with the output voltage of the solar power generation apparatus and inputs it to the orthogonal transformer. At that time, when the output of the wind power generation does not reach the solar power generation, the hybrid power generation system cuts off the DC parallel connection of the wind power. Further, when there is no output from the solar power generation device such as at night, the hybrid power generation system cuts off the solar power generation output terminal and inputs only the output of wind power generation to the orthogonal converter.

  Furthermore, when both solar power generation and wind power generation do not reach a predetermined voltage, the hybrid power generation system cuts off any connection. At this time, in the case where the wind power generation power is weak but not less than a value that can be charged, the hybrid power generation system shifts to a charging state and charges the battery. Furthermore, when the amount of stored power reaches a predetermined level or more and the output from the system is lower than a predetermined output value, the hybrid power generation system shifts to a discharge state.

  In addition, when the output of wind power generation is high and there is a surplus even after internal consumption is deducted, the hybrid power generation system sends it to an external power system or charges surplus power to a battery in the system.

  According to this hybrid power generation system, a step-up / step-down voltage regulator with good controllability is provided on the output side of wind power generation, enabling effective parallel power generation, and adopting a capacitor, which is less than the standard power that is rapidly rising and falling in a short time In addition, it is possible to increase the efficiency of the entire system by storing surplus power and discharging when there is no wind power output.

In the case of the DC link system, the power generated by the wind power generator is converted into AC power having a constant frequency and a constant voltage by an inverter. The inverter used at that time is usually a voltage source inverter (see, for example, Patent Document 2). The voltage source inverter obtains a DC voltage smoothed by a capacitor on the converter output side, and then converts it into an AC voltage having a predetermined frequency in an inverter unit.
JP 2005-51955 A JP 2007-89399 A

  However, a wind power generation system having a battery such as a storage battery has a problem that the system becomes large and costs increase. In addition, the use of the battery deteriorates the efficiency of the entire system, and it is difficult to make the best use of wind energy.

  Further, since the output voltage waveform of the voltage source inverter used in the conventional wind power generation system is a PWM waveform, it becomes a voltage waveform containing many high-order harmonic components, which may cause loss and noise. In addition, since the voltage source inverter includes a smoothing capacitor that requires periodic replacement, the maintenance cost increases. If a current source inverter is used instead of a voltage source inverter, not only the smoothing capacitor needs to be replaced, but also a thyristor can be used to realize a low-capacity and large capacity thyristor. There is a problem that there is no arc extinguishing capability, a new commutation circuit is required, and the circuit configuration becomes complicated.

  The present invention solves the above-mentioned problems of the prior art, and it is an object to provide a hybrid wind power generation system that can be realized at a low cost with a simple configuration and maintains a constant output regardless of changes in wind speed. And

  In order to solve the above problems, a hybrid wind power generation system according to the present invention includes a first generator mechanically connected to a shaft of a wind turbine and outputting electric power according to wind power, A converter unit that rectifies the electric power output from the first generator and converts it into direct current; a DC link unit that supplies a DC current that is smoothed based on the electric power converted into direct current by the converter unit; and the DC link unit An inverter unit that converts the direct current supplied by the inverter into an alternating current, a second generator that is driven by a prime mover and outputs electric power, an alternating current power output by the inverter unit, and an electric power output by the second generator And a power supply unit that outputs predetermined power.

  According to the first aspect of the present invention, it is possible to provide a hybrid wind power generation system that can be realized at a low cost and with a simple configuration and that maintains a constant output regardless of changes in wind speed.

  Hereinafter, embodiments of a hybrid wind power generation system of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention. First, the configuration of the present embodiment will be described. As shown in FIG. 1, the hybrid wind power generation system of the present embodiment includes a wind turbine 10, a permanent magnet synchronous generator 12, a thyristor rectifier 14, a DC link unit 16, a thyristor inverter 20, a prime mover 22, a synchronous generator 24, and The waveform improving reactor 26 is configured.

  The wind turbine 10 converts the kinetic energy of the wind into rotational energy and drives the permanent magnet synchronous generator 12. This wind turbine 10 is, for example, for the purpose of more effectively extracting and converting wind energy, and the peripheral speed ratio (blade peripheral speed and inflow) that maximizes the output coefficient (equivalent to efficiency) regardless of wind speed fluctuations. A shift control operation method is employed in which the rotational speed is manipulated so as to maintain the wind speed ratio). Since the hybrid wind power generation system of the present embodiment includes the DC link unit 16 described later, it is possible to independently control the frequency of the wind turbine 10 without depending on the frequency (for example, 50 Hz) on the output side of the thyristor inverter 20. There is.

  The permanent magnet synchronous generator 12 corresponds to the first generator of the present invention, is mechanically connected to the shaft of the wind turbine 10, and outputs electric power according to the wind force. The generator connected to the wind turbine 10 is not necessarily a permanent magnet synchronous generator, but may be a synchronous generator. However, the permanent magnet synchronous generator 12 does not require a power supply circuit for field excitation, has a simple structure and is easy to maintain, and is considered to be optimal for the present invention.

The thyristor rectifier 14 corresponds to the converter unit of the present invention, and rectifies the electric power output from the permanent magnet synchronous generator 12 to convert it into direct current. The element of the rectifier used here does not necessarily need to be a thyristor. However, by configuring the converter thyristor rectifier 14 using thyristors, it is possible to adjust the voltage V _d shown in FIG.

  The DC link unit 16 supplies a smoothed direct current based on the electric power converted into direct current by the thyristor rectifier. The DC link unit 16 is configured by a DC reactor 18.

  The thyristor inverter 20 corresponds to the inverter unit of the present invention, and converts the direct current supplied by the DC link unit 16 into alternating current. The thyristor inverter 20 is a separately-excited thyristor inverter, and performs commutation by applying a reverse bias from the output side.

  Therefore, in the hybrid wind power generation system of the present invention, the thyristor rectifier 14, the DC link unit 16, and the thyristor inverter 20 constitute a current source inverter.

  The prime mover 22 is, for example, a gas turbine or a gasoline engine, and drives the synchronous generator 24 by converting various kinds of energy existing in nature into mechanical energy.

  The synchronous generator 24 corresponds to the second generator of the present invention, is driven by the prime mover 22, and outputs AC power. The synchronous generator 24 supplies an insufficient amount of electric power (effective amount) that cannot be covered by the output of the permanent magnet synchronous generator 12 in order to keep the output of the entire system constant. That is, the synchronous generator 24 supplies insufficient power when the power output from the thyristor inverter 20 is insufficient for the predetermined power required by the load. Therefore, this hybrid wind power generation system supplies necessary predetermined power to the load regardless of fluctuations in wind power.

  Furthermore, the synchronous generator 24 supplies reactive power necessary for commutation to the thyristor inverter 20 via a waveform improving reactor 26 described later. The synchronous generator 24 supplies reactive power required by a load connected to the output side of the hybrid wind power generation system. The output of the permanent magnet synchronous generator 12 becomes DC power via the DC link unit 16 and cannot supply reactive power required by the load. Therefore, the synchronous generator 24 is essential for reactive power supply in the present invention.

  The waveform improvement reactor 26 corresponds to the power supply unit of the present invention, and combines the AC power output by the thyristor inverter 20 and the power output by the synchronous generator 24, and outputs predetermined power.

The waveform improving reactor 26 is the same as the waveform improving reactor described in Japanese Patent Application Laid-Open No. 11-150866. By appropriately selecting the self-inductances L ₁ and L ₂ and the mutual inductance M of the two reactor coils. Since the initial transient inductance of the synchronous generator 24 can be canceled out equivalently, the waveform depression of the output voltage due to the commutation of the thyristor inverter 20 can be eliminated as a result.

  The waveform improving reactor 26 is wound on the same iron core and connected in series so that magnetic fluxes generated by both currents are added when current flows from both the thyristor inverter 20 and the synchronous generator 24. Consists of two coils.

  As shown in FIG. 2, the waveform improving reactor 26 is the same so that when current flows from both the thyristor inverter 20 and the output end of the hybrid wind power generation system, magnetic fluxes generated by both currents cancel each other. It may be composed of two coils wound on an iron core and connected in series.

Note that the waveform improving reactor 26 is not necessarily an indispensable constituent element, and it is possible to operate the hybrid wind power generation system even when it is not included in the configuration. However, some sort of filter is considered necessary. When the waveform improving reactor 26 is employed, the self-inductances L ₁ and L _{2 of} the two reactor coils constituting the waveform improving reactor 26 and the mutual inductance M are used in order to suppress the current overlap angle to a predetermined value or less. Must be selected appropriately.

  Next, the operation of the present embodiment configured as described above will be described. First, the wind turbine 10 converts the kinetic energy of the wind into rotational energy and drives the permanent magnet synchronous generator 12. The permanent magnet synchronous generator 12 is mechanically connected to the shaft of the wind turbine 10 and outputs electric power to the thyristor rectifier 14 according to the wind force. The thyristor rectifier 14 rectifies the electric power output from the permanent magnet synchronous generator 12 and converts it into direct current. The DC link unit 16 supplies a smoothed direct current based on the electric power converted into direct current by the thyristor rectifier. The thyristor inverter 20 converts the direct current supplied from the DC link unit 16 into alternating current.

  On the other hand, the prime mover 22 drives the synchronous generator 24 by converting various kinds of energy existing in the natural world into mechanical energy. In order to keep the rotational speed of the synchronous generator 24 constant even when the output of the synchronous generator 24 fluctuates due to a load change or the like, a governor (governor) (not shown) of the prime mover 22 controls the output of the prime mover 22. To do. The synchronous generator 24 is driven by the prime mover 22 and outputs AC power. The synchronous generator 24 supplies the load with insufficient power (effective amount) that cannot be covered by the output of the permanent magnet synchronous generator 12 in order to keep the output of the entire system constant. Furthermore, the synchronous generator 24 supplies reactive power necessary for commutation to the thyristor inverter 20 via the waveform improving reactor 26. The synchronous generator 24 supplies reactive power required by a load connected to the output side of the hybrid wind power generation system. In addition, since the synchronous generator 24 controls the commutation of the thyristor inverter 20, the output frequency of the hybrid wind power generation system is determined based on the rotational speed of the synchronous generator 24.

  The waveform improvement reactor 26 combines the AC power output by the thyristor inverter 20 and the power output by the synchronous generator 24 and outputs predetermined power. At that time, the waveform improving reactor 26 removes a harmonic component of the output voltage.

FIG. 3 is a circuit diagram illustrating an equivalent circuit of the hybrid wind power generation system according to the first embodiment of the present invention. The thyristor inverter 20, the synchronous generator 24, and the waveform improving reactor 26 shown in FIG. 1 are equivalent to the thyristor inverter 20a, the synchronous generator 24a, and the waveform improving reactor 26a shown in FIG. 3, respectively. The electric power output from the waveform improving reactor 26 a is supplied to the three-phase load 30. The output of the thyristor rectifier 14 is shown in the DC power supply voltage V _d.

In order to control the hybrid wind power generation system of the present invention, the control advance angle γ of the thyristor inverter 20 and the field voltage V _f of the synchronous generator 24 can be manipulated. The maximum power control of the wind turbine generator in the hybrid wind power generation system is achieved by adjusting the control lead angle γ using the phase control circuit of the thyristor inverter 20. Further, the field voltage _Vf of the synchronous generator 24 is controlled by adjusting the conduction rate in the DC chopper circuit, for example, so as to keep the output voltage of the hybrid wind power generation system constant.

Assuming that the output voltage V _l−l and the frequency f of the hybrid wind power generation system are constant and the output coefficient C _p of the wind turbine 10 is constant, and the wind speed is V _w , the DC link current I _d is , V _w ² is proportional. This is because the input P _t of the wind turbine 10 equal to the product of the DC link voltage V _d and the DC link current I _{d in} the ideal state (no loss) is proportional to V _w ³ and the output coefficient C _p is constant. DC link voltage V _d is due to be proportional to the wind speed V _w in the case of. Therefore, the I _d -V _w characteristic does not depend on load conditions such as power factor.

The control advance angle γ of the thyristor inverter 20 needs to be decreased as the wind speed _Vw increases. Further, the current overlap angle u increases as the DC link current I _d increases. Further, the output _{P w} of the wind turbine 10 increases with increasing wind speed _{V w.}

Further, when the load power factor is low or when the load current is high and the output is large, the control advance angle γ of the thyristor inverter 20 becomes large when the wind speed _Vw is the same. When the control advance angle γ and the current overlap angle u are equal, a commutation failure occurs in the thyristor inverter 20, and the hybrid wind power generation system becomes inoperable. Therefore, the control advance angle γ needs to be controlled in a state larger than the current overlap angle u.
Apparent power of the synchronous generator 24, except for the load condition of the pure resistance load (power factor 1), seems to increase with increasing wind speed V _w. This is because reactive power required for commutation and load of the thyristor inverter 20 increases.

  FIG. 4 is a diagram illustrating an example of an output voltage waveform of the hybrid wind power generation system according to the first embodiment of the present invention. As shown in FIG. 4, THD (Total Harmonic Distortion) is suppressed to about 3%, indicating that the output voltage waveform is hardly distorted and the waveform improving reactor 26 is effective.

FIG. 5 shows the characteristics of the output P _{o of} the entire hybrid wind power generation system with respect to the wind speed V _w, the output P _SG of the synchronous generator 24, and the output P _w of the wind turbine 10. In FIG. 5, the output P _o of the entire hybrid wind power generation system is described for the cases of 1 kW, 2 kW, and 3 kW, but this output P _o is determined by the load condition. Output P _w of the permanent magnet synchronous generator 12 is increased with the increase of wind speed V _w. However, since the output P _SG of the synchronous generator 24 decreases as the wind speed _Vw increases, a constant output _Po as shown in FIG. 5 is obtained as a result. Note that the Roman numerals shown in FIG. 5 indicate the respective cases where the output _{Po of the} entire system and the power factor of the load are different conditions. In any case, the above-mentioned tendency is shown. Yes. Moreover, the experimental result has shown the value close | similar to a theoretical value. Therefore, this hybrid wind power generation system can achieve maximum power point tracking of wind power generation and minimize fuel supplied to the prime mover 22 that drives the synchronous generator 24.

  As described above, according to the hybrid wind power generation system according to the form of the first embodiment, a battery such as a storage battery is unnecessary, so that the configuration is low-cost and simple, and wind energy is always used efficiently with maximum efficiency. be able to. Further, the simple configuration indicates that the system is highly reliable and highly efficient.

  Furthermore, the output of the entire hybrid wind power generation system can be kept constant regardless of changes in wind speed.

  In addition, by adopting a current source inverter, not only the maintenance cost required for periodic smoothing capacitor replacement like a conventional voltage type inverter, but also the use of a thyristor as a rectifier is inexpensive. Large capacity can be easily realized.

  In addition, since the synchronous generator 24 is provided, the permanent magnet synchronous generator 12 based on wind energy is used for the power required by the load in order to keep the output of the entire hybrid wind power generation system constant as described above. Insufficient power (effective amount) that cannot be covered by the output of can be supplied to the load. Further, the synchronous generator 24 supplies reactive power necessary for the load and also supplies reactive power necessary for commutation of the thyristor inverter 20. Therefore, a commutation circuit originally required by the thyristor inverter 20 is not required, and a current source inverter can be employed in the present invention. Therefore, by connecting the prime mover 22 to the synchronous generator 24 and actively generating power, the synchronous generator 24 has the three actions and effects described above for the hybrid wind power generation system of the present invention.

  Furthermore, since the waveform improving reactor 26 is provided, the waveform distortion of the output voltage can be completely removed in principle, and extremely high-quality power can be supplied to the load.

  Moreover, since the hybrid wind power generation system of the present invention can be used with high efficiency in any place where the wind is strong to some extent on the earth, the economic and social effects are considered to be extremely large on a global scale.

  The hybrid wind power generation system according to the present invention can be used for a power generation system operated in conjunction with an existing power system or the like.

It is a block diagram which shows the structure of the hybrid wind power generation system of the form of Example 1 of this invention. It is a block diagram which shows another structural example of the hybrid wind power generation system of the form of Example 1 of this invention. It is a circuit diagram which shows the equivalent circuit of the hybrid wind power generation system of the form of Example 1 of this invention. It is a figure which shows one example of the output voltage waveform of the hybrid wind power generation system of the form of Example 1 of this invention. It is a figure which shows the characteristic of the output of the whole hybrid wind power generation system with respect to the wind speed in the hybrid wind power generation system of Example 1 of this invention, the output of a synchronous generator, and the output of a wind turbine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wind turbine 12 Permanent magnet synchronous generator 14 Thyristor rectifier 16 DC link part 18 DC reactor 20, 20a Thyristor inverter 22 Prime mover 24, 24a Synchronous generator 26, 26a Waveform improvement reactor 30 Three-phase load

Claims (4)

A first generator mechanically connected to the shaft of the wind turbine and outputting electric power according to the wind;
A converter unit that rectifies the electric power output by the first generator and converts it into direct current;
A DC link unit for supplying a DC current smoothed based on the electric power converted into DC by the converter unit;
An inverter unit for converting a direct current supplied by the DC link unit into an alternating current;
A second generator driven by a prime mover and outputting electric power;
A power supply unit that combines the AC power output by the inverter unit and the power output by the second generator, and outputs predetermined power,
A hybrid wind power generation system comprising: The inverter unit is configured by a thyristor inverter,
The hybrid wind power generation system according to claim 1, wherein the second generator supplies reactive power necessary for commutation to the thyristor inverter through the power supply unit.   The power supply unit is wound on the same iron core and connected in series so that magnetic fluxes generated by both currents are added when current flows from both the inverter unit and the second generator. The hybrid wind power generation system according to claim 1 or 2, wherein the hybrid wind power generation system is a waveform improving reactor composed of two coils.   The power supply unit is wound on the same iron core so that magnetic fluxes generated by both currents cancel each other when current flows from both the inverter unit and the output end of the hybrid wind power generation system. The hybrid wind power generation system according to claim 1 or 2, wherein the hybrid wind power generation system is a waveform improving reactor including two connected coils.

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