JP5785958B2 - Secondary excitation wind power conversion device, secondary excitation wind power control device, and control method for secondary excitation wind power conversion device - Google Patents

Description

  The present invention relates to a converter for secondary excitation wind power generation, a control apparatus for secondary excitation wind power generation, and a control method for a converter for secondary excitation wind power generation.

  In recent years, along with the acceleration of renewable energy demand, construction of wind power generation facilities is being promoted in various parts of the world. This is because wind power generation is cheap in the renewable energy field.

  Wind power generation generates electric power from wind energy, but when the wind changes, the rotation of the rotating shaft of the generator changes. On the other hand, a so-called secondary excitation generator (Doubly-Fed Induction Generator) has been proposed to maintain the output of the generator at a constant frequency. In this secondary excitation type wind power generator, the output power of the wind power generator is kept at a constant frequency by controlling the power supplied to the rotor of the power generator. Such a technique is described in, for example, JP-A-2005-198429.

  In addition, in order to supply stable power from wind power generation to the power grid, control of the power converter that controls the output power of the generator without following the output command when the rotational speed of the windmill deviates from a predetermined range Technology has been proposed. Such a technique is described in, for example, Japanese Patent Application Laid-Open No. 2007-244199.

JP 2005-198429 A JP 2007-244199 A

  In the control of the converter for secondary excitation type power generation, when the rotation speed of the generator exceeds the upper and lower limit range centering on the synchronous speed (slip 0), there is a margin in the voltage for supplying power to the rotor of the generator Disappears. Therefore, generally, when the rotation speed of the generator exceeds the upper and lower limit range, power supply to the rotor of the generator must be suppressed. Furthermore, if the divergence increases, the power supply must be stopped.

  Even when the wind speed suddenly decreases and the wind speed immediately increases, the power supply to the rotor of the generator may have to be stopped in some cases even if the slip range is deviated for a short time. In particular, if such an event occurs frequently, the amount of power generation for the time required for restarting may be reduced, and the life of components such as a switch of the converter may be shortened.

  An object of the present invention is to provide a secondary excitation wind power conversion device, a secondary excitation wind power generation control device, and a secondary excitation wind power conversion device that can maintain power generation even when the rotational speed of the generator changes. It is to provide a control method.

  In order to achieve the above object, in the present invention, a system-side converter connected to a stator and a system, which converts AC power and DC power to control a smoothed DC voltage, and a smoothed DC voltage A generator-side converter that converts AC to AC and supplies an AC voltage having a slip frequency to the rotor, and includes rotation speed information corresponding to the rotation speed of the rotor and frequency information corresponding to the frequency of the output voltage of the stator; When the slip frequency is out of the predetermined range, the smoothed DC voltage is adjusted.

  According to the present invention, it is possible to maintain power generation even when the rotational speed of the generator changes.

FIG. 3 is an explanatory diagram of a power converter according to the first embodiment. Explanatory drawing of the slip frequency calculator 1019 of Example 1. FIG. Explanatory drawing of the DC voltage command value calculator 1018 of Example 1. FIG. Explanatory drawing of the DC voltage command value calculator 1018 of Example 1. FIG. Explanatory drawing of the DC voltage command value calculator 1018 of Example 2. FIG. Explanatory drawing of the DC voltage command value calculator 1018 of Example 2. FIG. Explanatory drawing of the DC voltage command value calculator 1018 of Example 3. FIG. Explanatory drawing of the DC voltage command value calculator 1018 of Example 3. FIG. Explanatory drawing of the DC voltage command value calculator 1018 of Example 4. FIG. Explanatory drawing of the DC voltage command value calculator 1018 of Example 4. FIG.

  Hereinafter, examples will be described with reference to the drawings.

  This embodiment will be described with reference to FIGS. 1, 2, 3, and 4. FIG.

<Outline configuration>
A power converter 1006 illustrated in FIG. 1 is a wind power generation power conversion system including a plurality of devices. The generator 1003 receives the rotational energy of the wing 1001 that rotates in response to the wind via the shaft 1002, and generates power by exciting the rotor of the generator 1003 with the generator-side converter 1009a. The electric power generated on the stator side of the generator 1003 is supplied to the electric power system 1005 via the stator side system wiring 1004, and the electric power generated or consumed on the rotor side is supplied to the stator side system via the power converter 1006. Returned to the wiring 1004. Note that a synchronous circuit breaker (air circuit breaker) 1021 for protecting the generator is attached to the stator side system wiring 1004.

  The power converter 1006 includes a power conversion unit 1007 and a control device 1010. The power conversion unit 1007 includes a DC capacitor 1008, a generator side converter 1009a, and a system side converter 1009b. The control device 1010 includes a generator rotation speed sensor 1011, a stator side voltage sensor 1012, a generator side converter current sensor 1013, a DC voltage sensor 1014, a system side converter current sensor 1015, a system side voltage sensor 1016, and a system side. Information from the current sensor 1017 and the wind turbine controller WTC is input. In addition, although each component of the control apparatus 1010 of FIG. 1 is shown with the block diagram, the control apparatus 1010 may be configured by one or a plurality of computers, and each function may be configured by software.

<Outline function>
The power conversion unit 1007 shown in FIG. 1 is controlled by the control device 1010 based on information from each sensor. The system power regulator APR calculates the generated power based on the information of the windmill control device WTC, the system side voltage sensor 1016, and the system current sensor 1017. The system power adjuster APR outputs the excitation current command value to the excitation current adjuster 1020 so that the generated power command from the wind turbine controller WTC matches the generated power calculation value.

  The excitation current adjuster 1020 compares the excitation current command value input from the system power adjuster APR with the excitation current detection value from the generator-side converter current sensor 1013, and calculates so that the command value matches the detection value. Then, a control signal is output to the generator-side converter 1009a. The voltage detection value of the stator side voltage sensor 1012 is used when the synchronous circuit breaker 1021 is turned on by synchronizing the stator voltage with the system voltage.

  The slip frequency calculator 1019 calculates the slip frequency fslip based on the information of the generator rotational speed sensor 1011 and the system side voltage sensor 1016 and outputs the result to the DC voltage command value calculator 1018. The slip frequency fslip is a rotational frequency (electrical angle) frot calculated from the generator rotational speed sensor (rotational speed (rotational frequency) of the rotor of the generator 1003) and a frequency fgrid calculated from the system side voltage sensor 1016 (system (Frequency of power) is calculated according to Equation 1.

[Formula 1]
fslip [%] = ((fgrid−frot) / fgrid) × 100
The DC voltage command value calculator 1018 calculates a DC voltage command value using the slip frequency, and outputs the DC voltage command to the adder / subtractor 1022.

  The adder / subtractor 1022 calculates the difference between the DC voltage command value and the DC voltage detection value detected by the DC voltage sensor 1014 and outputs the calculation result to the DC voltage regulator AVDCR.

  The DC voltage regulator AVDCR calculates a current command value for controlling the DC voltage based on the input information, and outputs the calculation result to the current regulator ACR.

  The current regulator ACR calculates a control amount for controlling the current based on a command from the DC voltage regulator AVDCR and information of the system side converter current sensor 1015, and outputs a control signal to the system side converter 1009b. .

  The system power regulator APR, the excitation current regulator 1020, the DC voltage regulator AVDCR, and the current regulator ACR are configured by, for example, a proportional integrator.

  FIG. 2 shows the relationship between the slip frequency fslip and the rotor voltage of the generator 1003. In the slip frequency calculator 1019, when the slip frequency changes from the slip frequency (0%) at the synchronous speed (eg, + 30% or −30%), the rotor voltage increases with a substantially constant slope. Or descend. At this time, the slip frequency calculator 1019 calculates the time change of the slip frequency and outputs the slip frequency to the DC voltage command value calculator 1018.

<Detailed functions>
The DC voltage command value calculator 1018 will be described with reference to FIGS. 3 and 4.
FIG. 3 shows the relationship between the DC voltage command calculated by the DC voltage command value calculator 1018 and the slip frequency. In the DC voltage command value calculator 1018, when the slip frequency is + 28% to + 30%, or -28% to -30%, the DC voltage command is calculated according to Equation 2, and the slip frequency is + 30% or more. Alternatively, the DC voltage command is set to be maintained at 105% of the rated DC voltage command when -30% or less. When the slip frequency is in the range of + 28% to -28%, the DC voltage command maintains the rated DC voltage command of 100%. Here, + 28%, + 30%, -28%, and -30% are exemplary, and other numerical values can be selected in accordance with the characteristics of each generator. The same applies to the following embodiments.

[Formula 2]
Inclination A = (Change in DC voltage command) 5% ÷ (Slip frequency change) 2%
FIG. 4 shows a processing flow of the DC voltage command value calculator 1018. The DC voltage command value calculator 1018 makes a determination 4001 when information on the slip frequency calculator 1019 is input. If the determination 4001 is not applicable, the calculation 4004 is executed to output information for maintaining the DC voltage command at the rated DC voltage command 100% to the adder / subtractor 1022. When it corresponds to the determination 4001, the determination 4002 is determined. When the determination 4002 is not satisfied, the calculation 4005 is executed and information for maintaining the DC voltage command at 105% is output to the adder / subtractor 1022. When the determination 4002 is satisfied, a result obtained by executing the calculation 4003 (command value = slope A × (| slip frequency | −28%) + 100%) is set as a DC voltage command and is output to the adder / subtractor 1022.

  In the first embodiment, by providing the <detailed function>, frequent stopping and restarting when slip at a low wind speed is large can be prevented, so that the amount of power generation is increased and the life of parts such as a switch is extended. be able to. In addition, since the DC voltage command value is changed gradually, disturbance to the control system can be reduced.

  In the first embodiment, (1) the allowable range of the slip frequency has been described as ± 30% of the rated frequency (50 Hz or 60 Hz), but ± 30% is the winding ratio of the generator and the converter. The value is determined by the DC voltage, and the same effect can be obtained even when the value is other than ± 30%. Further, the value of (2) ± 28% may be determined so that T1> T2 from the time T1 when the speed is changed to ± 30% (a value that changes with the inertia constant) and the response T2 of the DC voltage. The start of the change may be within the slip range (± 30% in this embodiment). (3) Although the upper limit of the DC voltage command value is 105%, it is a value determined by the elements of the converter, and may be a value other than 105%.

  The present embodiment will be described with reference to FIGS. 1, 2, 5, and 6. FIG. In the following Examples 2 to 4, only the parts different from Example 1 will be described. The description of the same part is omitted.

<Outline configuration>
Same as Example 1.

<Outline function>
Same as Example 1.

<Detailed functions>
The DC voltage command value calculator 1018 will be described with reference to FIGS.
FIG. 5 shows the relationship between the DC voltage command value calculated by the DC voltage command value calculator 1018 and the slip frequency. The DC voltage command value calculator 1018 is set so that the DC voltage command is maintained at 105% of the rated DC voltage command when the slip frequency is + 30% or more or −30% or less. When the slip frequency is in the range of + 30% to −30%, the DC voltage command maintains the rated DC voltage command of 100%.

  FIG. 6 shows a processing flow of the DC voltage command value calculator 1018. When the information of the slip frequency calculator 1019 is input, the DC voltage command value calculator 1018 first makes a determination 6001. If the determination 6001 is not applicable, the calculation 6002 (command value = 100%) is executed, and information for maintaining the DC voltage command at the rated DC voltage command 100% is output to the adder / subtractor 1022. When the determination 6001 is satisfied, an operation 6003 (command value = 105%) is executed, and information for maintaining the DC voltage command at 105% is output to the adder / subtractor 1022.

  In the second embodiment, since the <detailed function> is provided, frequent stop and restart when the slip at a low wind speed is large can be prevented, so that the amount of power generation is increased and the life of parts such as a switch is extended. Can be stabilized in terms of control.

  In the second embodiment, (1) the allowable range of the slip frequency has been described as ± 30% of the rated frequency (50 Hz or 60 Hz), but ± 30% is the winding ratio of the generator and the converter. The value is determined by the DC voltage, and the same effect can be obtained even when the value is other than ± 30%. (2) Although the upper limit of the DC voltage command value is 105%, it is a value determined by the elements of the converter and may be a value other than 105%.

  This embodiment will be described with reference to FIGS. 1, 2, 7, and 8.

<Outline configuration>
Same as Example 1.

<Outline function>
Same as Example 1.

<Detailed functions>
The DC voltage command value calculator 1018 will be described with reference to FIGS.
FIG. 7 shows the relationship between the DC voltage command value calculator 1018 and the slip frequency fslip. In the DC voltage command value calculator 1018, when the slip frequency is within a range of + 28% to -28%, the DC voltage command maintains a rated DC voltage command of 100%, and the slip frequency is + 32% or more. Alternatively, the DC voltage command is set to be maintained at 105% of the rated DC voltage command when it is within −32%.

  When the slip frequency is in the state 7001 (−30% <slip frequency ≦ −28%, or + 28% ≦ slip frequency <+ 30%), the DC voltage command is either the expression 7003 or the command 100%. The result depends on whether the slip frequency has changed from the range of −28% <fslip <+ 28%, fslip <−32%, or + 32% <fslip. Determined.

  When the slip frequency is in the state 7002 (−32% <slip frequency ≦ −30%, or + 30% ≦ slip frequency <+ 32%), the DC voltage command is either the expression 7004 or the command 105%. The result depends on whether the slip frequency has changed from the range of −28% <fslip <+ 28%, fslip <−32%, or + 32% <fslip. Determined.

[Formula 3]
Inclination B = (Change in DC voltage command) 5% ÷ (Slip frequency change) 2%
[Formula 7003]
DC voltage command = slope B × (| slip frequency | −28%) + 100%
[Formula 7004]
DC voltage command = slope B × (| slip frequency | −30%) + 100%
FIG. 8 shows a processing flow of the DC voltage command value calculator 1018. The DC voltage command value calculator 1018 executes determination 8001 when the information of the slip frequency calculator 1019 is input. If the determination 8001 is not satisfied, the calculation 8006 is executed to output a command for maintaining the DC voltage command at 100% to the adder / subtractor 1022 and a flag = 1 is substituted for reference. When it corresponds to the determination 8001, the process proceeds to the determination 8002. If the determination 8002 is not applicable, an operation 8007 is executed to output a command for maintaining the DC voltage command at 105% to the adder / subtractor 1022, and flag = 0 is substituted for reference. If the determination 8002 is satisfied, the process proceeds to the determination 8003.

  If the determination 8003 is satisfied, the process proceeds to the determination 8004. When the determination 8004 is satisfied (that is, −30% <slip frequency <+ 30% and the previous value is 100%), a command to maintain the DC voltage command at 100% by executing the calculation 8008 The result is output to the adder / subtractor 1022. If the determination 8004 is not applicable, the calculation 8009 is executed, a DC voltage command is determined according to the expression 7003, and is output to the adder / subtractor 1022.

  If the determination 8003 is not applicable, the process proceeds to determination 8005. When the determination 8005 is satisfied (that is, when slip frequency ≦ −30% or + 30% ≦ slip frequency and the previous command is 105%), the calculation 8010 is executed to set the DC voltage command to 105 A command to maintain at% is output to the adder / subtractor 1022. When the determination 8005 is not satisfied, the calculation 8011 is executed, a DC voltage command is determined according to the expression 7004, and is output to the adder / subtractor 1022.

  In this third embodiment, by adding hysteresis characteristics to the first embodiment, in addition to the effects of the first embodiment, unnecessary when the slip frequency fluctuates at ± 28%, ± 30%, or ± 32%. Changes in the DC voltage command value can be prevented, and control disturbance can be reduced.

  In the third embodiment, (1) the allowable range of the slip frequency is described as ± 30% of the rated frequency (50 Hz or 60 Hz), but ± 30% is the winding ratio of the generator and the converter. The value is determined by the DC voltage, and the same effect can be obtained even when the value is other than ± 30%. Further, the value of (2) ± 28% may be determined so that T1> T2 from the time T1 when the speed is changed to ± 30% (a value that changes with the inertia constant) and the response T2 of the DC voltage. The start of the change may be within the slip range (± 30% in this embodiment). The value of (3) ± 32% is a standard for expressing the hysteresis characteristics. Further, (4) the upper limit of the DC voltage command value is 105%, but it is a value determined by the elements of the converter, and may be a value other than 105%.

  This embodiment will be described with reference to FIG. 1, FIG. 2, FIG. 9, and FIG.

<Outline configuration>
Same as Example 1.

<Outline function>
Same as Example 1.

<Detailed functions>
The DC voltage command value calculator 1018 will be described with reference to FIGS.
FIG. 9 shows the relationship between the DC voltage command value calculator 1018 and the slip frequency. In the DC voltage command value calculator 1018, when the slip frequency is within a range of + 29% to -29%, the DC voltage command maintains a rated DC voltage command of 100%, and the slip frequency is + 30% or more. Alternatively, it is set so that the DC voltage command is maintained at 105% of the rated DC voltage command when -30% or less.

  When the slip frequency is in the state 9001 (−30% ≦ slip frequency ≦ −29%, or + 29% ≦ slip frequency ≦ + 30%), the DC voltage command is either the command 100% or the command 105%. Whether the slip frequency has changed from the range of −29% <fslip <+ 29%, fslip <−30%, or + 30% <fslip. It depends on.

  FIG. 10 shows a processing flow of the DC voltage command value calculator 1018. The DC voltage command value calculator 1018 executes determination 10001 when the information of the slip frequency calculator 1019 is input. If the determination 10001 is not applicable, a calculation 10004 is executed to output a command for maintaining the DC voltage command at 100% to the adder / subtractor 1022, and a reference flag = 1 is substituted. When it corresponds to the determination 10001, the process proceeds to determination 10002. When the determination 10002 is satisfied, the calculation 10005 is executed to output a command for maintaining the DC voltage command at 105% to the adder / subtractor 1022, and the reference flag = 0 is substituted. If the determination 10002 is not applicable, the determination 10003 is executed. When the determination 10003 is satisfied, the calculation 10006 is executed to output a command for setting the DC voltage command to 100% to the adder / subtractor 1022. If the determination 10003 is not applicable, the calculation 10007 is executed and a command for setting the DC voltage command to 105% is output to the adder / subtractor 1022.

  In the fourth embodiment, by adding hysteresis characteristics to the second embodiment, in addition to the effects of the second embodiment, an unnecessary change in the DC voltage command value when the slip frequency fluctuates at ± 29% or ± 30%. Can be prevented, and the control can be more stable.

  In the second embodiment, (1) the allowable range of the slip frequency has been described as ± 30% of the rated frequency (50 Hz or 60 Hz), but ± 30% is the winding ratio of the generator and the converter. The value is determined by the DC voltage, and the same effect can be obtained even when the value is other than ± 30%. The value of (2) ± 29% may be determined so that T1> T2 from the time T1 (the value that changes with the inertia constant) when the speed is changed to ± 30% and the DC voltage response T2. The start of the change may be within the slip range (± 30% in this embodiment). (3) Although the upper limit of the DC voltage command value is 105%, it is a value determined by the elements of the converter, and may be a value other than 105%.

1001 Wings 1002 Shaft 1003 Generator 1004 Stator side system wiring 1005 Power system 1006 Power converter 1007 Power conversion unit 1008 DC capacitor 1009a Generator side converter 1009b System side converter 1010 Controller 1011 Generator rotation speed sensor 1012 Stator Side voltage sensor 1013 Generator side converter current sensor 1014 DC voltage sensor 1015 System side converter current sensor 1016 System side voltage sensor 1017 System side current sensor 1018 DC voltage command value calculator 1019 Slip frequency calculator 1020 Excitation current controller 1021 Synchronous circuit breaker 1022 Adder / subtracter 4001, 4002, 6001, 8001, 8002, 8003, 8004, 8005, 10001, 10002, 10003 judgment 4003, 4004, 4005, 6002 6003,8006,8007,8008,8009,8010,8011,10004,10005,10006,10007 calculation 7001,7002,9001 state 7003,7004 formula WTC wind turbine controller ACR current regulator APR system power regulator AVDCR DC voltage regulator

Claims (6)

The power generated by the generator stator is controlled by supplying current to the rotor of the generator by means of power conversion means connected to the generator stator and the system. In the converter for secondary excitation wind power generation that is rotated by the wing rotating around the axis by receiving the force of
A system-side converter connected to the stator and the system to control the DC voltage smoothed by converting the power between the AC voltage and the DC unit;
A generator-side converter that converts the smoothed DC voltage to AC and outputs a voltage to the rotor;
The smoothing is performed when the slip frequency is out of a predetermined range from the slip frequency based on the rotation speed information corresponding to the rotation speed of the rotor and the frequency information corresponding to the frequency of the AC voltage of the stator. with to change the direct current voltage,
It has means for detecting that the rotational speed of the generator has an upper and lower limit slip set value centering on the synchronous speed, and out of the range of the slip set value, and increasing the smoothed DC voltage. Secondary excitation wind power converter.
The power generated by the generator stator is controlled by supplying current to the rotor of the generator by means of power conversion means connected to the generator stator and the system. In the converter for secondary excitation wind power generation that is rotated by the wing rotating around the axis by receiving the force of
A system-side converter connected to the stator and the system to control the DC voltage smoothed by converting the power between the AC voltage and the DC unit;
A generator-side converter that converts the smoothed DC voltage to AC and outputs a voltage to the rotor;
The smoothing is performed when the slip frequency is out of a predetermined range from the slip frequency based on the rotation speed information corresponding to the rotation speed of the rotor and the frequency information corresponding to the frequency of the AC voltage of the stator. Change the DC voltage
It comprises means for detecting that the rotational speed of the generator has an upper and lower limit slip set value centered on the synchronous speed, returning to the slip set value range, and lowering the smoothed DC voltage. Secondary excitation wind power converter.
2. The converter for secondary excitation wind power generation according to claim 1 , further comprising means for increasing the DC voltage with a certain slope when the means increases the smoothed DC voltage .
3. The converter for secondary excitation wind power generation according to claim 2 , wherein, when the means lowers the smoothed DC voltage, the DC voltage is lowered with a certain slope .
In Claim 1 , it detects that the rotation speed of the said generator has the upper / lower limit slip setting value 1 centering on a synchronous speed, and the slip setting value 2 inside slip setting value 1, and remove | deviates from the range of slip setting value 1. A secondary-excited wind power conversion device comprising a current-voltage command calculation unit that increases the smoothed power voltage stepwise .
3. The method according to claim 2 , wherein the rotational speed of the generator has an upper / lower limit slip set value 1 centered on the synchronous speed and a slip set value 2 inside the slip set value 1 and is detected to return to the range of the slip set value 2. Then, a converter for secondary excitation wind power generation , comprising a direct-current voltage command calculation unit for stepping down the voltage of the smoothed power in a step-like manner .

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