Control device for a power conversion device

Abstract

A control device for a power conversion device that can appropriately compensate the voltage of a system when an unbalanced short circuit occurs is provided. The control device includes: a current command value generation unit that generates a tentative positive-phase d-axis current command value, a tentative positive-phase q-axis current command value, a tentative negative-phase d-axis current command value, and a tentative negative-phase q-axis current command value to compensate the voltage of the AC side of the power converter; a limiting unit that respectively sets limit values for the tentative positive-phase d-axis current command value, the tentative positive-phase q-axis current command value, the tentative negative-phase d-axis current command value, and the tentative negative-phase q-axis current command value so that the current value of the AC side of the power converter does not exceed a preset value; and a control unit that controls the power converter based on a determined positive-phase d-axis current command value, a determined positive-phase q-axis current command value, a determined negative-phase d-axis current command value, and a determined negative-phase q-axis current command value respectively obtained from the tentative positive-phase d-axis current command value, the tentative positive-phase q-axis current command value, the tentative negative-phase d-axis current command value, and the tentative negative-phase q-axis current command value within the limit values.

Description

Technical Field

[0001] The present disclosure relates to a control device for a power conversion device. Background Art

[0002] Non-Patent Document 1 discloses a power conversion system. In this power conversion system, a DC power supply and a system are connected via a power conversion device.

[0003] Prior Art Documents

[0004] Non-Patent Documents

[0005] Non-Patent Document 1: "Technical requirements for the connection and operation of customer installations to the high voltage network (TCR high voltage) - English translation of VDE-AR-N 4120:2018-11", November 2018, VDE Verband der Elektrotechnik Elektronik Informationstechnik e.V. Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the power conversion system described in Non-Patent Document 1, an unbalanced short circuit may occur. In this case, it is necessary to compensate the voltage of the system.

[0008] The present disclosure is made to solve the above problems. An object of the present invention is to provide a control device for a power conversion device that can appropriately compensate the voltage of the system when an unbalanced short circuit occurs.

[0009] Means for Solving the Problems

[0010] The control device for the power conversion device according to the present invention includes: a first conversion unit that converts the detected value of the current on the AC side of a power converter that converts DC power into AC power into a positive-phase d-axis current value and a negative-phase d-axis current value; a second conversion unit that converts the detected value of the voltage on the AC side of the power converter into a positive-phase d-axis voltage value and a negative-phase d-axis voltage value; a current command value generation unit that generates a tentative positive-phase d-axis current command value, a tentative positive-phase q-axis current command value, a tentative negative-phase d-axis current command value, and a tentative negative-phase q-axis current command value based on the detected value of the voltage on the DC side of the power converter, the detected value of the current, the positive-phase d-axis current value and the negative-phase d-axis current value from the first conversion unit, and the positive-phase d-axis voltage value and the negative-phase d-axis voltage value from the second conversion unit, in order to compensate for the voltage on the AC side of the power converter; a limit unit that respectively sets limit values for the tentative positive-phase d-axis current command value, the tentative positive-phase q-axis current command value, the tentative negative-phase d-axis current command value, and the tentative negative-phase q-axis current command value generated by the current command value generation unit, so that the current value on the AC side of the power converter does not exceed a preset value; and a control unit that controls the power converter based on the determined positive-phase d-axis current command value, the determined positive-phase q-axis current command value, the determined negative-phase d-axis current command value, and the determined negative-phase q-axis current value obtained respectively from the tentative positive-phase d-axis current command value, the tentative positive-phase q-axis current command value, the tentative negative-phase d-axis current command value, and the tentative negative-phase q-axis current value within the limit values set by the limit unit.

[0011] Advantages of the Invention

[0012] According to the present invention, the voltage of the system can be appropriately compensated when an unbalanced short circuit occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a configuration diagram of a power conversion system of a control device for a power conversion device according to Embodiment 1.

[0014] Figure 2 It is a block diagram for explaining the outline of the operation of the control device for the power conversion device according to Embodiment 1.

[0015] Figure 3 It is a block diagram for explaining a method for generating a limit value for a tentative positive-phase q-axis current command value performed by the control device for the power conversion device according to Embodiment 1.

[0016] Figure 4 It is a block diagram for explaining a method for generating a limit value for a tentative negative-phase d-axis current command value and a limit value for a tentative negative-phase q-axis current command value performed by the control device for the power conversion device according to Embodiment 1.

[0017] Figure 5 It is a block diagram showing a method for generating a limit value of a tentative positive-phase d-axis current command value by the control device of the power conversion device according to Embodiment 1.

[0018] Figure 6 It is a diagram showing the relationship between the tentative positive-phase current command value and the tentative negative-phase current command value of the control device of the power conversion device according to Embodiment 1.

[0019] Figure 7 It is a diagram showing the first example of Mode N with priority given to the negative-phase current by the control device of the power conversion device according to Embodiment 1.

[0020] Figure 8 It is a diagram showing the second example of Mode N with priority given to the negative-phase current by the control device of the power conversion device according to Embodiment 1.

[0021] Figure 9 It is a diagram showing the first example of Mode P with priority given to the positive-phase current by the control device of the power conversion device according to Embodiment 1.

[0022] Figure 10 It is a diagram showing the second example of Mode P with priority given to the positive-phase current by the control device of the power conversion device according to Embodiment 1.

[0023] Figure 11 It is a diagram showing the first example of Mode E where neither the negative-phase current nor the positive-phase current is given priority by the control device of the power conversion device according to Embodiment 1.

[0024] Figure 12 It is a diagram showing the second example of Mode E where neither the negative-phase current nor the positive-phase current is given priority by the control device of the power conversion device according to Embodiment 1.

[0025] Figure 13 It is a diagram showing the magnitude of the positive-phase current in each mode of the control device of the power conversion device according to Embodiment 1.

[0026] Figure 14 It is a diagram showing the magnitude of the negative-phase current in each mode of the control device of the power conversion device according to Embodiment 1.

[0027] Figure 15 It is a diagram showing the magnitude of the positive-phase voltage in each mode of the control device of the power conversion device according to Embodiment 1.

[0028] Figure 16 It is a diagram showing the magnitude of the negative-phase voltage in each mode of the control device of the power conversion device according to Embodiment 1.

[0029] Figure 17 This is a hardware configuration diagram of the control device of the power conversion device according to Embodiment 1. Specific Embodiment

[0030] The embodiments will be described with reference to the accompanying drawings. In addition, in each figure, the same or corresponding parts are given the same reference numerals. The repeated description of such parts is appropriately simplified or omitted.

[0031] Embodiment 1.

[0032] Figure 1 This is a configuration diagram of a power conversion system of a control device of a power conversion device to which Embodiment 1 is applied.

[0033] In Figure 1 the power conversion system, the DC power supply 1 outputs DC power of a magnitude obtained based on the DC voltage value V dc and the DC current value i dc . For example, the DC power supply 1 is a solar power generation device. For example, the DC power supply 1 is a power storage device. The power conversion device 2 converts the DC power from the DC power supply 1 into AC power.

[0034] The power conversion device 2 includes a power converter 3, a filter reactor 4, a filter capacitor 5, a PLL circuit 6, and a control device 7.

[0035] The power converter 3 includes a plurality of semiconductor switching elements such as IGBTs or MOSFETs. The power converter 3 converts the DC power into three-phase AC power according to the switching control information. The power converter 3 outputs three-phase AC power obtained based on the AC current value i o and the AC voltage value v o .

[0036] One end of the filter reactor 4 is connected to the output terminal of the power converter 3. The filter reactor 4 has an inductance L f . One end of the filter capacitor 5 is connected to the other end of the filter reactor 4. The other end of the filter capacitor 5 is connected to a reference potential such as a ground potential. The filter capacitor 5 has a capacitance C f .

[0037] The PLL circuit 6 outputs information on the phase θ g . The information on the phase θ g is information used to detect the phase error from the reference frequency information for phase synchronization.

[0038] The control device 7 is based on the AC current value i o , the AC voltage value v o and the phase θ g, output switch control information. The switch control information is gate drive information for driving the semiconductor switch elements of the power converter 3 respectively.

[0039] One end of the grid connection reactor L is connected to the connection point of the filter reactor 4 and the filter capacitor 5. The other end of the grid connection reactor L is connected to the AC power system A as an AC power source. The grid connection reactor L has an inductance L g .

[0040] In the embodiment, an unbalanced short circuit may occur on the AC side of the power converter 3. For example, a short circuit between two phases generated among the three phases of UVW may occur. For example, a short circuit where a certain one of the three phases of UVW is grounded may occur.

[0041] At this time, the control device 7 controls the power converter 3 so that the three-phase AC current value io does not exceed a preset value after compensating the voltage on the AC side of the power converter 3.

[0042] Next, use Figure 2 to illustrate the outline of the operation of the control device 7.

[0043] Figure 2 is a block diagram for illustrating the outline of the operation of the control device of the power conversion device according to Embodiment 1.

[0044] As Figure 2 shown, the control device 7 includes a first conversion unit 8, a second conversion unit 9, a current command value generation unit 10, a first limit unit 11, a second limit unit 12, a third limit unit 13, a fourth limit unit 14, and a control unit 15.

[0045] The first conversion unit 8 receives the input of the information of the AC current value i0 from a detector (not shown). The first conversion unit 8 receives the input of the information of the phase θ g . The first conversion unit 8 outputs the information of the positive-phase d-axis current value i g and the negative-phase d-axis current value i o_d+ based on the AC current value i0 and the phase θ o_d－ .

[0046] The second conversion unit 9 receives the input of the information of the AC voltage value v0 (not shown). The first conversion unit 8 receives the input of the information of the phase θ g . The second conversion unit 9 outputs the information of the positive-phase d-axis voltage value v g and the negative-phase d-axis voltage value v o_d+ based on the AC voltage value v0 and the phase θ o_d－ .

[0047] The current command value generation unit 10 receives the positive-phase d-axis current value i from the first conversion unit 8 o_d+and the reverse-phase d-axis current value i o_d－ Input of information on the direct-axis voltage value v o_d+ and the reverse-phase d-axis voltage value v o_d－ Input of information on the DC voltage value v dc not shown is received by the current command value generation unit 10. Input of information on the DC current value i dc not shown is received by the current command value generation unit 10. The current command value generation unit 10 outputs a tentative direct-axis current command value i o_d+ for MPPT control or PQ control based on the direct-axis current value i o_d－ and the reverse-phase d-axis current value i o_d+ and the direct-axis voltage value v o_d－ and the reverse-phase d-axis voltage value v dc and the DC voltage value v dc and the DC current value i o_ref_d+ as well as a tentative direct-axis current command value i o_ref_q+ a tentative direct-axis q-axis current command value i o_ref_d－ a tentative reverse-phase d-axis current command value i o_ref_q－ and a tentative reverse-phase q-axis current command value i

[0048] The first limiting unit 11 receives an input of information on 0 as the lower limit value. The first limiting unit 11 receives an input of information on the limit value i o_ref_d+_limit as the upper limit value. The first limiting unit 11 receives an input of information on the tentative direct-axis current command value i o_ref_d+ from the current command value generation unit 10. When the tentative direct-axis current command value i o_ref_d+ is a value between 0 and the limit value i o_ref_d+_limit the first limiting unit 11 outputs the information on the tentative direct-axis current command value i o_ref_d+l as the determined direct-axis current command value i o_ref_d+ as it is. When i o_ref_d+ is 0 or less, the first limiting unit 11 outputs information on 0 as the determined direct-axis current command value i o_ref_d+l When the tentative direct-axis current command value i o_ref_d+ is greater than or equal to the limit value i o_ref_d+_limit the first limiting unit 11 outputs the information on the limit value i o_ref_d+l as the determined direct-axis current command value i o_ref_d+limit

[0049] The second limiting unit 12 receives an input of information on the limit value -i o_ref_q+_limit as the lower limit value. The second limiting unit 12 receives an input of information on the limit value i o_ref_q+_limit ​Input of information. The second limiting unit 12 receives the tentative direct-axis q-axis current command value i from the current command value generation unit 10 o_ref_q+ Input of information. In the case where the tentative direct-axis q-axis current command value i o_ref_q+ is between the limit value -i o_ref_q+_limit and the limit value i o_ref_q+_limit the second limiting unit 12 outputs the information of the tentative direct-axis q-axis current command value i as the determined direct-axis q-axis current command value i o_ref_q+l as it is. In the case where the tentative direct-axis q-axis current command value i o_ref_q+ is less than or equal to the limit value -i o_ref_q+ the second limiting unit 12 outputs the information of the limit value -i as the determined direct-axis q-axis current command value i o_ref_q+_limit In the case where the tentative direct-axis q-axis current command value i o_ref_q+l is greater than or equal to the limit value i o_ref_q+_limit the second limiting unit 12 outputs the information of the limit value i as the tentative direct-axis q-axis current command value i o_ref_q+ In the case where the tentative direct-axis q-axis current command value i o_ref_q+_limit is greater than or equal to the limit value i o_ref_q+l the second limiting unit 12 outputs the information of the limit value i as the tentative direct-axis q-axis current command value i o_ref_q+_limit as it is.

[0050] The third limiting unit 13 receives the input of the information of the limit value -i as the lower limit value o_ref_d－_limit The third limiting unit 13 receives the input of the information of the limit value i as the upper limit value o_ref_d－_limit The third limiting unit 13 receives the input of the information of the tentative quadrature-axis d-axis current command value i from the current command value generation unit 10 o_ref_d－ In the case where the tentative quadrature-axis d-axis current command value i o_ref_d－ is between the limit value -i o_ref_d－_limit and the limit value i o_ref_d－_limit the third limiting unit 13 outputs the information of the tentative quadrature-axis d-axis current command value i as the determined quadrature-axis d-axis current command value i o_ref_d－l as it is. In the case where the tentative quadrature-axis d-axis current command value i o_ref_d－ is less than or equal to the limit value -i o_ref_d－ the third limiting unit 13 outputs the information of the limit value -i as the tentative quadrature-axis d-axis current command value i o_ref_d－_limit In the case where the tentative quadrature-axis d-axis current command value i o_ref_d－l is greater than or equal to the limit value i o_ref_d－_limit the third limiting unit 13 outputs the information of the limit value i as the tentative quadrature-axis d-axis current command value i o_ref_d－ In the case where the tentative quadrature-axis d-axis current command value i o_ref_d－_limit is greater than or equal to the limit value i o_ref_d－l the third limiting unit 13 outputs the information of the limit value i as the tentative quadrature-axis d-axis current command value i o_ref_d－_limit as it is.

[0051] The fourth limiting unit 14 receives the input of the limit value -i as the lower limit valueo_ref_q－_limit Input of the information. The 4th limiting unit 14 receives the limiting value i as the upper limit value o_ref_q－_limit Input of the information. The 4th limiting unit 14 receives the tentative reverse-phase q-axis current command value i from the current command value generation unit 10 o_ref_q－ Input of the information. For the tentative reverse-phase q-axis current command value i o_ref_q－ being the limiting value -i o_ref_q－_limit and the limiting value i o_ref_q－_limit when it is between the values, the 4th limiting unit 14 outputs the information of the tentative reverse-phase q-axis current command value i as the determined reverse-phase q-axis current command value i o_ref_q－l as it is. When the tentative reverse-phase q-axis current command value i o_ref_q－ is less than or equal to the limiting value -i o_ref_q－ the 4th limiting unit 14 outputs the information of the limiting value -i as the determined reverse-phase q-axis current command value i o_ref_q+_limit When the tentative reverse-phase q-axis current command value i o_ref_q－l is greater than or equal to the limiting value i o_ref_q－_limit the 4th limiting unit 14 outputs the information of the limiting value i as the determined reverse-phase q-axis current command value i o_ref_q+ When the tentative reverse-phase q-axis current command value i o_ref_q－_limit is greater than or equal to the limiting value i o_ref_q－l the 4th limiting unit 14 outputs the information of the limiting value i as the determined reverse-phase q-axis current command value i o_ref_q－_limit as it is.

[0052] The control unit 15 receives the input of the information of the determined direct-phase d-axis current command value i from the 1st limiting unit 11 o_ref_d+l The control unit 15 receives the input of the information of the determined direct-phase q-axis current command value i from the 2nd limiting unit 12 o_ref_q+l The control unit 15 receives the input of the information of the determined reverse-phase d-axis current command value i from the 3rd limiting unit 13 o_ref_d－l The control unit 15 receives the input of the information of the determined reverse-phase q-axis current command value i from the 4th limiting unit 14 o_ref_q－l The control unit 15 outputs the switching control information for current control and PWM control based on the determined direct-phase d-axis current command value i o_ref_d+l , the determined direct-phase q-axis current command value i o_ref_q+l , the determined reverse-phase d-axis current command value i o_ref_d－l and the determined reverse-phase q-axis current command value i o_ref_q－l .

[0053] Next, use Figure 3 to explain the generation method of the limiting value i o_ref_q+_limit and the limiting value -i o_ref_q+_limit .

[0054] Figure 3It is a block diagram showing a method for generating a limit value for a tentative positive-phase q-axis current command value by a control device of a power conversion device according to Embodiment 1.

[0055] As Figure 3 shown, the control device 7 includes a first subtraction unit 16, a first multiplication unit 17, a first addition unit 18, a first division unit 19, a first selection unit 20, and a first inversion unit 21.

[0056] The first subtraction unit 16 receives the input of information on the rated current value i max as a preset threshold value. The first subtraction unit 16 receives the input of information on the absolute value of the tentative inverse-phase d-axis current command value i o_ref_d－ and the tentative inverse-phase q-axis current command value i o_ref_q－ to obtain the tentative inverse-phase current command value i o_ref－ . The first subtraction unit 16 outputs the information on the value obtained by subtracting the absolute value of the tentative inverse-phase current command value i max from the rated current value i o_ref－ .

[0057] The first multiplication unit 17 receives the input of information on the rated current value i max . The first multiplication unit 17 receives the input of information on the absolute value of the tentative positive-phase q-axis current command value i o_ref_q+ . The first multiplication unit 17 outputs the information on the value obtained by multiplying the rated current value i max by the absolute value of the tentative positive-phase q-axis current command value i o_ref_q+ .

[0058] The first addition unit 18 receives the input of information on the absolute value of the tentative inverse-phase current command value i o_ref－ . The first addition unit 18 receives the input of information on the absolute value of the tentative positive-phase q-axis current command value i o_ref_q+ . The first addition unit 18 outputs the information on the value obtained by adding the absolute value of the tentative inverse-phase current command value i o_ref－ to the absolute value of the tentative positive-phase q-axis current command value i o_ref_q+ .

[0059] The first division unit 19 receives the input of information on the output value of the first multiplication unit 17. The first division unit 19 receives the input of information on the output value of the first addition unit 18. The first division unit 19 outputs the information on the value obtained by dividing the output value of the first multiplication unit 17 by the output value of the first addition unit 18.

[0060] The first selection unit 20 receives the input of information on the output value of the first subtraction unit 16. The first selection unit 20 receives the input of information on the rated current value i maxInput of the information. The first selection unit 20 accepts the input of the information of the output value of the first division unit 19. The first selection unit 20 outputs the output value of the first subtraction unit 16, the rated current value i o_ref_q+_limit as one of the information of the output value of the rated current value i max and the output value of the first division unit 19.

[0061] For example, when the mode N with reverse-phase current priority is selected, the first selection unit 20 outputs the information of the output value of the first subtraction unit 16 as the limit value i o_ref_q+_limit For example, when the mode P with positive-phase current priority is selected, the first selection unit 20 outputs the information of the rated current value i max For example, when the mode E where neither reverse-phase current nor positive-phase current is prioritized is selected, the first selection unit 20 outputs the output value of the first division unit 19.

[0062] The first inversion unit 21 accepts the input of the information of the output value of the first selection unit 20. The first inversion unit 21 outputs the information of the value obtained by inverting the sign of the output value of the first selection unit 20 as the limit value -i o_ref_q+_limit Next, the generation method of the limit value i

[0063] Then, use Figure 4 to illustrate the limit value i o_ref_d－_limit the limit value -i o_ref_d－_limit the limit value i o_ref_q－_limit and the limit value -i o_ref_q－_limit generation method.

[0064] Figure 4 is a block diagram for explaining the generation method of the limit value for the tentative reverse-phase d-axis current command value and the limit value for the tentative reverse-phase q-axis current command value by the control device of the power conversion device in Embodiment 1.

[0065] As Figure 4 shown, the control device 7 includes a second subtraction unit 22, a second multiplication unit 23, a second addition unit 24, a second division unit 25, a second selection unit 26, a third division unit 27, a first absolute value calculation unit 28, a third multiplication unit 29, a second inversion unit 30, a fourth division unit 31, a second absolute value calculation unit 32, a fourth multiplication unit 33, and a third inversion unit 34.

[0066] The second subtraction unit 22 accepts the input of the information of the rated current value i max The second subtraction unit 22 accepts the input of the absolute value of the tentative positive-phase q-axis current command value i o_ref_q+ The first subtraction unit 16 outputs the information of the value obtained by subtracting the absolute value of the tentative positive-phase q-axis current command value i max from the rated current value i o_ref_q+ obtained.

[0067] The second multiplication unit 23 receives the input of the information of the rated current value i max The second multiplication unit 23 receives the input of the information of the absolute value of the tentative reverse-phase current command value i o_ref－ The first multiplication unit 17 outputs the information of the value obtained by multiplying the rated current value i max by the absolute value of the tentative reverse-phase current command value i o_ref－

[0068] The second addition unit 24 receives the input of the information of the absolute value of the tentative reverse-phase current command value i o_ref－ The second addition unit 24 receives the input of the information of the absolute value of the tentative direct-axis positive-phase current command value i o_ref_q+ The first addition unit 18 outputs the information of the value obtained by adding the absolute value of the tentative reverse-phase current command value i o_ref－ to the absolute value of the tentative reverse-phase current command value i o_ref_q+

[0069] The second division unit 25 receives the input of the information of the output value of the second multiplication unit 23. The second division unit 25 receives the input of the information of the output value of the second addition unit 24. The second division unit 25 outputs the information of the value obtained by dividing the output value of the second multiplication unit 23 by the output value of the second addition unit 24

[0070] The second selection unit 26 receives the input of the information of the rated current value i max The second selection unit 26 receives the input of the information of the output value of the second subtraction unit 22. The second selection unit 26 receives the input of the information of the output value of the second division unit 25. The second selection unit 26 outputs, as the limit value i o_ref－_limit the information of the rated current value i max or one of the information of the output value of the second subtraction unit 22 and the output value of the second division unit 25

[0071] For example, when the reverse-phase current priority mode N is selected, the second selection unit 26 outputs, as the limit value i o_ref－_limit the information of the rated current value i max For example, when the direct-axis positive-phase current priority mode P is selected, the second selection unit 26 outputs the output value of the second subtraction unit 22. For example, when the mode E in which neither the reverse-phase current nor the direct-axis positive-phase current is prioritized is selected, the second selection unit 26 outputs the output value of the second division unit 25

[0072] The third division unit 27 receives the input of the information of the absolute value of the reverse-phase direct-axis voltage value v o_d－ The third division unit 27 receives the input of the reverse-phase voltage value v obtained based on the reverse-phase direct-axis voltage value v o_d－ and the reverse-phase quadrature-axis voltage value v o_q－ o o－ ​​Input of information on the absolute value. The third division unit 27 outputs the inverse-phase d-axis voltage value v o_d－ divided by the absolute value of the inverse-phase voltage value v o－ of the information on the resulting value of the absolute value.

[0073] The first absolute value calculation unit 28 receives the input of the output value of the third division unit 27. The first absolute value calculation unit 28 outputs the information on the absolute value of the output value of the third division unit 27.

[0074] The third multiplication unit 29 receives the input of the information on the limit value i o_ref－_limit from the second selection unit 26. The third multiplication unit 29 receives the input of the information on the output value of the first absolute value calculation unit 28. The third multiplication unit 29 outputs, as the limit value i o_ref－_q－limit the information on the value obtained by multiplying the limit value i o_ref－_limit by the output value of the first absolute value calculation unit 28.

[0075] The second inversion unit 30 receives the input of the information on the output value of the third multiplication unit 29. The second inversion unit 30 outputs, as the limit value -i o_ref－_q－limit the information on the value obtained by inverting the sign of the output value of the third multiplication unit 29.

[0076] The fourth division unit 31 receives the input of the information on the absolute value of the inverse-phase q-axis voltage value v o_q－ The fourth division unit 31 receives the input of the information on the absolute value of the inverse-phase voltage value v o－ The fourth division unit 31 outputs the inverse-phase q-axis voltage value v o_q－ divided by the absolute value of the inverse-phase voltage value v o－ of the information on the resulting value of the division.

[0077] The second absolute value calculation unit 32 receives the input of the output value of the fourth division unit 31. The second absolute value calculation unit 32 outputs the information on the absolute value of the output value of the fourth division unit 31.

[0078] The fourth multiplication unit 33 receives the input of the information on the limit value i o_ref－_limit from the second selection unit 26. The fourth multiplication unit 33 receives the input of the information on the output value of the second absolute value calculation unit 32. The fourth multiplication unit 33 outputs, as the limit value i o_ref－_d－limit the information on the value obtained by multiplying the limit value i o_ref－_limit by the output value of the second absolute value calculation unit 32.

[0079] The third inversion unit 34 receives the input of the information on the output value of the fourth multiplication unit 33. The third inversion unit 34 outputs, as the limit value -i o_ref－_d－limit the information on the value obtained by inverting the sign of the output value of the fourth multiplication unit 33.

[0080] Next, use Figure 5 to illustrate the generation method of the limit value -i o_ref_d+_limit .

[0081] Figure 5 It is a block diagram for illustrating the generation method of the limit value for the tentative positive-phase d-axis current command value by the control device of the power conversion device in Embodiment 1.

[0082] As Figure 5 shown, the control device 7 includes a fifth multiplication unit 35, a sixth multiplication unit 36, a third addition unit 37, a first square root calculation unit 38, a third subtraction unit 39, a fourth addition unit 40, a fourth subtraction unit 41, a fourth multiplication unit 42, and a second square root calculation unit 43.

[0083] The fifth multiplication unit 35 receives the input of information determining the reverse-phase d-axis current command value i o_ref_d－_l . The fifth multiplication unit 35 outputs information on the value obtained by squaring the determined reverse-phase d-axis current command value i o_ref_d－_l .

[0084] The sixth multiplication unit 36 receives the input of information determining the reverse-phase q-axis current command value i o_ref_q－_l . The sixth multiplication unit 36 outputs information on the value obtained by squaring the determined reverse-phase q-axis current command value i o_ref_q－_l .

[0085] The third addition unit 37 receives the input of information on the output value of the fifth multiplication unit 35. The third addition unit 37 receives the input of information on the output value of the sixth multiplication unit 36. The third addition unit 37 outputs information on the value obtained by adding the output value of the fifth multiplication unit 35 to the output value of the sixth multiplication unit 36.

[0086] The first square root calculation unit 38 receives the input of information on the output value of the third adder. The first square root calculation unit 38 outputs information on the square root value of the output value of the third adder.

[0087] The third subtraction unit 39 receives the input of information on the rated current value i max . The third subtraction unit 39 receives the input of information on the output value of the first square root calculation unit 38. The third subtraction unit 39 outputs information on the value obtained by subtracting the output value of the first square root calculation unit 38 from the rated current value i max .

[0088] The fourth addition unit 40 receives the input of information on the output value of the third subtraction unit 39. The fourth addition unit 40 receives the input of information determining the positive-phase q-axis current command value i o_ref_q+_l . The fourth addition unit 40 outputs the value obtained by adding the output value of the third subtraction unit 39 to the determined positive-phase q-axis current command value i o_ref_q+_lInformation on the obtained value.

[0089] The fourth subtraction unit 41 receives the input of the information on the output value of the third subtraction unit 39. The fourth subtraction unit 41 receives the input of the information for determining the positive-phase q-axis current command value i o_ref_q+_l The fourth subtraction unit 41 outputs the information on the value obtained by subtracting the value obtained by determining the positive-phase q-axis current command value i from the output value of the third subtraction unit 39. o_ref_q+_l Information on the obtained value.

[0090] The fourth multiplication unit 42 receives the input of the information on the output value of the fourth addition unit 40. The fourth multiplication unit 42 receives the input of the information on the output value of the fourth subtraction unit 41. The fourth multiplication unit 42 outputs the information on the value obtained by multiplying the output value of the fourth addition unit 40 by the output value of the fourth subtraction unit 41.

[0091] The second square root calculation unit 43 receives the input of the information on the output value of the fourth multiplication unit 42. The second square root calculation unit 43 outputs the information on the square root value of the output value of the fourth multiplication unit 42 as the limit value i o_ref_d+_limit

[0092] Next, use Figure 6 to explain the relationship between the tentative positive-phase current command value i o_ref+ and the tentative negative-phase current command value i o_ref－

[0093] Figure 6 is a diagram for explaining the relationship between the tentative positive-phase current command value and the tentative negative-phase current command value of the control device of the power conversion device based on Embodiment 1.

[0094] On the AC side of the power converter 3, the maximum value I of the current in the U phase U is represented by the following equation (1). The maximum value I of the current in the V phase V is represented by the following equation (2). The maximum value I of the current in the W phase W is represented by the following equation (3).

[0095] [Equation 1]

[0096]

[0097] [Equation 2]

[0098]

[0099] [Equation 3]

[0100]

[0101] In Equations (1) to (3), θ pn is the phase difference between the positive-phase current and the negative-phase current.​​

[0102] Among the maximum values \(I\) of the current in the U-phase, U the maximum value \(I\) of the current in the V-phase, V and the maximum value \(I\) of the current in the W-phase, W when the phase difference \(\theta\) pn is one of 0, +2π / 3, and -2π / 3, the maximum value MAX{\(I\) U , \(I\) V , \(I\) W} can be obtained. The maximum value MAX{\(I\) U , \(I\) V , \(I\) W} is represented by the following formula (4).

[0103] [Equation 4]

[0104]

[0105] The control device 7 controls the power converter 3 so that the following formula (5) holds.

[0106] [Equation 5]

[0107] MAX{\(I\) u , \(I\) v , \(I\) w} ≤ \(i\) max (5)

[0108] Specifically, the control device 7 controls the power converter 3 so that the following formula (6) holds.

[0109] [Equation 6]

[0110]

[0111] More specifically, the control device 7 controls the power converter 3 so that the following formula (7) holds.

[0112] [Equation 7]

[0113]

[0114] Next, an example of the reverse-phase current-priority mode N will be described using Figure 7 and Figure 8 .

[0115] Figure 7 is a diagram for explaining the first example of the reverse-phase current-priority mode N performed by the control device of the power conversion device according to Embodiment 1. Figure 8 is a diagram for explaining the second example of the reverse-phase current-priority mode N performed by the control device of the power conversion device according to Embodiment 1.

[0116] Tentative reverse-phase d-axis current command value i o_ref_d- is represented by the following equation (8).

[0117] [Equation 8]

[0118]

[0119] Tentative reverse-phase q-axis current command value i o_ref_q- is represented by the following equation (9).

[0120] [Equation 9]

[0121]

[0122] Tentative reverse-phase current command value i o_ref- The absolute value of is represented by the following equation (10).

[0123] [Equation 10]

[0124]

[0125] Limit value i o_ref_q+_limit is represented by the following equation (11).

[0126] [Equation 11]

[0127]

[0128] Determined reverse-phase current command value i o_ref-_1 is represented by the following equation (12).

[0129] [Equation 12]

[0130]

[0131] Limit value i o_ref_d+_limit is represented by the following equation (13).

[0132] [Equation 13]

[0133]

[0134] In Figure 7 the first example of, the absolute value of the tentative positive-phase q-axis current command value i o_ref_q+ is larger than the absolute value of the limit value i o_ref_q+_limit . In this case, the absolute value of the determined positive-phase q-axis current command value i o_ref_q+_1 is limited to the absolute value of the limit value i o_ref_q+_limit .

[0135] In Figure 8 the second example of, the tentative positive-phase q-axis current command value i o_ref_q+is smaller than the limit value i in absolute value. In this case, the positive-phase q-axis current command value i o_ref_q+_limit is not limited to the limit value i o_ref_q+_1 in absolute value. At this time, the positive-phase current command value i o_ref_q+_limit is determined. o_ref+_1 To determine the positive-phase d-axis current command value i o_ref_d+_1 and the positive-phase q-axis current command value i o_ref_q+_1 are added together.

[0136] Next, Figure 9 and Figure 10 are used to illustrate the first example of the positive-phase current priority mode P.

[0137] Figure 9 is a diagram for explaining the first example of the positive-phase current priority mode P performed by the control device of the power conversion device according to Embodiment 1. Figure 10 is a diagram for explaining the second example of the positive-phase current priority mode P performed by the control device of the power conversion device according to Embodiment 1.

[0138] The absolute value of the tentative positive-phase q-axis current command value i o_ref_q+ is represented by the following equation (14).

[0139] [Equation 14]

[0140] |i o_ref_q+ | = |-k × (1 - |v o +|)| (14)

[0141] The limit value i o_ref-_limit is represented by the following equation (15).

[0142] [Equation 15]

[0143] i o_ref-_limit = i max - |i o_ref_q+ | (15)

[0144] The limit value i o_ref_d-_limit is represented by the following equation (16).

[0145] [Equation 16]

[0146]

[0147] The limit value i o_ref_d-_limit is represented by the following equation (17).

[0148] [Equation 17]

[0149]

[0150] Determine the reverse-phase current command value i o_ref-_1 It is represented by the following equation (18).

[0151] [Equation 18]

[0152]

[0153] Limit value i o_ref_d+_limit It is represented by the following equation (19).

[0154] [Equation 19]

[0155]

[0156] In Figure 9 In the first example, the absolute value of the tentative reverse-phase current command value i o_ref- is larger than the absolute value of the limit value i o_ref-_limit In this case, the absolute value of the determined reverse-phase current command value i o_ref-_1 is limited to the absolute value of the limit value i o_ref-_limit of the absolute value.

[0157] In Figure 10 In the second example, the absolute value of the tentative reverse-phase current command value i o_ref- is smaller than the absolute value of the limit value i o_ref-_limit In this case, the absolute value of the determined reverse-phase current command value i o_ref-_1 is not limited to the absolute value of the limit value i o_ref-_limit of the absolute value. At this time, the positive-phase current command value i o_ref+_1 is determined to be the sum of the determined positive-phase d-axis current command value i o_ref_d+_1 and the determined positive-phase q-axis current command value i o_ref_q+_1 .

[0158] Next, using Figure 11 and Figure 12 to explain the first example of Mode E where neither the reverse-phase current nor the positive-phase current is prioritized.

[0159] Figure 11 is a diagram for explaining the first example of Mode E where neither the reverse-phase current nor the positive-phase current is prioritized by the control device of the power conversion device according to Embodiment 1. Figure 12 is a diagram for explaining the second example of Mode E where neither the reverse-phase current nor the positive-phase current is prioritized by the control device of the power conversion device according to Embodiment 1.

[0160] Limit value i o_ref_q+_limit It is represented by the following equation (20).

[0161] [Equation 20]

[0162]

[0163] Limit value i o_ref_-limit is represented by the following formula (21).

[0164] [Formula 21]

[0165]

[0166] Limit value i o_ref_d-_limit is represented by the following formula (22).

[0167] [Formula 22]

[0168]

[0169] Limit value i o_ref_d-_limit is represented by the following formula (23).

[0170] [Formula 23]

[0171]

[0172] Determine the reverse-phase current command value i o_ref_-_1 is represented by the following formula (23).

[0173] [Formula 24]

[0174]

[0175] Limit value i o_ref_d+_limit is represented by the following formula (25).

[0176] [Formula 25]

[0177]

[0178] In Figure 11 the first example, the absolute value of the tentative direct-axis q-axis current command value i o_ref_q+ is larger than the absolute value of the limit value i o_ref_q+_limit The absolute value of the tentative reverse-phase current command value i o_ref- is larger than the absolute value of the limit value i o_ref-_limit In this case, determine that the absolute value of the direct-axis q-axis current command value i o_ref_q+_1 is limited to the absolute value of the limit value i o_ref_q+_limit Determine that the absolute value of the reverse-phase current command value i o_ref-_1 is limited to the absolute value of the limit value i o_ref-_limit of the absolute value.

[0179] In Figure 12 the second example, the absolute value of the tentative direct-axis q-axis current command value i o_ref_q+ is larger than the absolute value of the limit value i o_ref_q+_limithas a small absolute value. The tentative reverse-phase current command value i o_ref- has an absolute value smaller than the limit value i o_ref-_limit is small. In this case, it is determined that the absolute value of the positive-phase q-axis current command value i o_ref_q+_1 is not limited to the absolute value of the limit value i o_ref_q+_limit . At this time, it is determined that the positive-phase current command value i o_ref+_1 is the sum of the determined positive-phase d-axis current command value i o_ref_d+_1 and the determined positive-phase q-axis current command value i o_ref_q+_1 .

[0180] Next, use Figure 13 to explain the magnitude of the positive-phase current based on each mode.

[0181] Figure 13 is a diagram for explaining the magnitude of the positive-phase current in each mode of the control device of the power conversion device according to Embodiment 1.

[0182] As Figure 13 shown, the magnitude of the positive-phase current varies according to the mode. Specifically, the positive-phase current is the largest when the mode P that prioritizes the positive-phase current is selected. The positive-phase current is the smallest when the mode N that prioritizes the reverse-phase current is selected. When the mode E that does not prioritize either the reverse-phase current or the positive-phase current is selected, the positive-phase current is between the magnitude of the positive-phase current when the mode P that prioritizes the positive-phase current is selected and the magnitude of the positive-phase current when the mode N that prioritizes the reverse-phase current is selected.

[0183] Next, use Figure 14 to explain the magnitude of the reverse-phase voltage based on each mode.

[0184] Figure 14 is a diagram for explaining the magnitude of the reverse-phase current in each mode of the control device of the power conversion device according to Embodiment 1.

[0185] As Figure 14 shown, the magnitude of the reverse-phase current varies according to the mode. Specifically, the reverse-phase current is the largest when the mode N that prioritizes the reverse-phase current is selected. The reverse-phase current is the smallest when the mode P that prioritizes the positive-phase current is selected. When the mode E that does not prioritize either the reverse-phase current or the positive-phase current is selected, the reverse-phase current is between the magnitude of the reverse-phase current when the mode N that prioritizes the reverse-phase current is selected and the magnitude of the reverse-phase current when the mode P that prioritizes the positive-phase current is selected.

[0186] Next, use Figure 15 to explain the magnitude of the positive-phase voltage in each mode.

[0187] Figure 15This is a diagram showing the magnitudes of the positive-phase voltages for the respective modes of the control device of the power conversion device according to Embodiment 1.

[0188] As Figure 15 shown, the magnitude of the positive-phase voltage varies according to the mode. Specifically, the positive-phase voltage is maximum when the mode P that prioritizes the positive-phase current is selected. The positive-phase voltage is minimum when the mode N that prioritizes the negative-phase current is selected. When the mode E in which neither the negative-phase current nor the positive-phase current is prioritized is selected, the magnitude of the positive-phase voltage is between the magnitude of the positive-phase voltage when the mode P that prioritizes the positive-phase current is selected and the magnitude of the positive-phase voltage when the mode N that prioritizes the negative-phase current is selected.

[0189] Next, Figure 16 is used to illustrate the magnitudes of the negative-phase voltages based on the respective modes.

[0190] Figure 16 This is a diagram showing the magnitudes of the negative-phase voltages for the respective modes of the control device of the power conversion device according to Embodiment 1.

[0191] As Figure 16 shown, the magnitude of the negative-phase voltage varies according to the mode. Specifically, the negative-phase voltage is maximum when the mode P that prioritizes the positive-phase current is selected. The negative-phase voltage is minimum when the mode N that prioritizes the negative-phase current is selected. When the mode E in which neither the negative-phase current nor the positive-phase current is prioritized is selected, the magnitude of the negative-phase voltage is between the magnitude of the negative-phase voltage when the mode P that prioritizes the positive-phase current is selected and the magnitude of the negative-phase voltage when the mode N that prioritizes the negative-phase current is selected.

[0192] According to Embodiment 1 described above, the control device 7 controls the power converter within the limit values based on the determined positive-phase d-axis current command value, determined positive-phase q-axis current command value, determined negative-phase d-axis current command value, and determined negative-phase q-axis current command value obtained from the tentative positive-phase d-axis current command value, tentative positive-phase q-axis current command value, tentative negative-phase d-axis current command value, and tentative negative-phase q-axis current command value, respectively. Therefore, when an unbalanced short circuit occurs, the voltage of the system can be appropriately compensated. Specifically, the voltage of the system can be compensated so that the current value on the AC side of the power converter 3 does not exceed the rated current value.

[0193] In addition, the control device 7 changes the limit values according to each mode. Therefore, the voltage of the system can be compensated according to the situation so that the current value on the AC side of the power converter 3 does not exceed the rated current value.

[0194] Next, Figure 17 is used to illustrate an example of the control device 7.

[0195] Figure 17It is a hardware configuration diagram of the control device of the power conversion device according to Embodiment 1.

[0196] Each function of the control device 7 can be implemented by a processing circuit. For example, the processing circuit includes at least one processor 100a and at least one memory 100b. For example, the processing circuit includes at least one dedicated hardware 200.

[0197] When the processing circuit includes at least one processor 100a and at least one memory 100b, each function of the control device 7 is implemented by software, firmware, or a combination of software and firmware. At least one of the software and the firmware is described as a program. At least one of the software and the firmware is stored in at least one memory 100b. At least one processor 100a realizes each function of the control device 7 by reading and executing the program stored in at least one memory 100b. At least one processor 100a is also called a central processing unit, a processing device, an arithmetic device, a microprocessor, a microcomputer, or a DSP. For example, at least one memory 100b is a non-volatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM, a magnetic disk, a floppy disk, an optical disk, a CD, an MD, or a DVD.

[0198] When the processing circuit includes at least one dedicated hardware 200, the processing circuit is implemented by, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. For example, each function of the control device 7 is implemented by the processing circuit respectively. For example, each function of the control device 7 is implemented by the processing circuit together.

[0199] Regarding each function of the control device 7, a part of it can also be implemented by dedicated hardware 200, and the other part can be implemented by software or firmware. For example, regarding the function of the control unit 15, it can be implemented by a processing circuit as dedicated hardware 200, and regarding the functions other than the function of the control unit 15, they can be implemented by at least one processor 100a reading and executing the program stored in at least one memory 100b.

[0200] In this way, the processing circuit realizes each function of the control device 7 through hardware 200, software, firmware, or a combination thereof.

[0201] Industrial Applicability

[0202] As described above, the control device of the power conversion device of the present invention can be used in a power conversion system.

[0203] Reference Numeral Explanation

[0204] 1 DC power supply; 2 power conversion device; 3 power converter; 4 filter reactor; 5 filter capacitor; 6 PLL circuit; 7 control device; 8 first conversion unit; 9 second conversion unit; 10 current command value generation unit; 11 first limiting unit; 12 second limiting unit; 13 third limiting unit; 14 fourth limiting unit; 15 control unit; 16 first subtraction unit; 17 first multiplication unit; 18 first addition unit; 19 first division unit; 20 first selection unit; 21 first inversion unit; 22 second subtraction unit; 23 second multiplication unit; 24 second addition unit; 25 second division unit; 26 second selection unit; 27 third division unit; 28 first absolute value calculation unit; 29 third multiplication unit; 30 second inversion unit; 31 fourth division unit; 32 second absolute value calculation unit; 33 fourth multiplication unit; 34 third inversion unit; 35 fifth multiplication unit; 36 sixth multiplication unit; 37 third addition unit; 38 first square root calculation unit; 39 third subtraction unit; 40 fourth addition unit; 41 fourth subtraction unit; 42 fourth multiplication unit; 43 second square root calculation unit; 100a processor; 100b memory; 200 hardware.

Claims

1. A control device for a power conversion device, characterized in that: It has: A first conversion unit that converts the detected value of the current on the AC side of a power converter that converts DC power into AC power into a positive-phase d-axis current value and a negative-phase d-axis current value; A second conversion unit that converts the detected value of the voltage on the AC side of the power converter into a positive-phase d-axis voltage value and a negative-phase d-axis voltage value; A current command value generation unit that generates a tentative positive-phase d-axis current command value, a tentative positive-phase q-axis current command value, a tentative negative-phase d-axis current command value, and a tentative negative-phase q-axis current command value based on the detected value of the voltage on the DC side of the power converter, the detected value of the current, the positive-phase d-axis current value and the negative-phase d-axis current value from the first conversion unit, and the positive-phase d-axis voltage value and the negative-phase d-axis voltage value from the second conversion unit, in order to compensate for the voltage on the AC side of the power converter; A limiting unit that respectively sets limit values for the tentative positive-phase d-axis current command value, the tentative positive-phase q-axis current command value, the tentative negative-phase d-axis current command value, and the tentative negative-phase q-axis current command value generated by the current command value generation unit, so that the current value on the AC side of the power converter does not exceed a preset value; and A control unit that controls the power converter based on the determined positive-phase d-axis current command value, the determined positive-phase q-axis current command value, the determined negative-phase d-axis current command value, and the determined negative-phase q-axis current value obtained respectively within the limit values set by the limiting unit according to the tentative positive-phase d-axis current command value, the tentative positive-phase q-axis current command value, the tentative negative-phase d-axis current command value, and the tentative negative-phase q-axis current command value.

2. The control device for a power conversion device according to claim 1, characterized in that: The limiting unit sets the limit value of the tentative positive-phase q-axis current command value based on the tentative negative-phase current command value obtained from the tentative negative-phase d-axis current command value and the tentative negative-phase q-axis current command value, the tentative positive-phase q-axis current command value, and the rated current value; the limiting unit sets the limit value of the tentative negative-phase d-axis current command value based on the tentative negative-phase current command value, the tentative positive-phase q-axis current command value, and the rated current value; the limiting unit sets the limit value of the tentative negative-phase q-axis current command value based on the tentative negative-phase current command value, the tentative positive-phase q-axis current command value, and the rated current value; the limiting unit sets the limit value of the tentative positive-phase d-axis current command value based on the determined positive-phase q-axis current command value, the determined negative-phase d-axis current command value, and the determined negative-phase q-axis current value.

3. The control device for a power conversion device according to claim 1 or 2, characterized in that: The limiting unit does not limit the tentative negative-phase d-axis current command value and the tentative negative-phase q-axis current command value, but limits the tentative positive-phase q-axis current command value.

4. The control device for a power conversion device according to claim 1 or 2, characterized in that: The above-mentioned limiting unit does not limit the above-mentioned tentative direct-axis q-axis current command value, but limits the tentative reverse-axis current command value obtained from the above-mentioned tentative reverse-axis d-axis current command value and the above-mentioned tentative reverse-axis q-axis current command value.

5. The control device of the power conversion device according to claim 1 or 2, characterized in that The above-mentioned limiting unit limits the tentative reverse-axis current command value obtained from the above-mentioned tentative reverse-axis d-axis current command value, the above-mentioned tentative reverse-axis q-axis current command value, the above-mentioned tentative reverse-axis d-axis current command value, and the above-mentioned tentative reverse-axis q-axis current command value.

6. The control device of the power conversion device according to claim 1 or 2, characterized in that The above-mentioned limiting unit is set to be able to select one of the following modes: A mode in which the above-mentioned tentative reverse-axis d-axis current command value and the above-mentioned tentative reverse-axis q-axis current command value are not limited, but the above-mentioned tentative direct-axis q-axis current command value is limited; A mode in which the above-mentioned tentative direct-axis q-axis current command value is not limited, but the tentative reverse-axis current command value obtained from the above-mentioned tentative reverse-axis d-axis current command value and the above-mentioned tentative reverse-axis q-axis current command value is limited; and A mode in which the above-mentioned tentative reverse-axis d-axis current command value, the above-mentioned tentative reverse-axis q-axis current command value, and the above-mentioned tentative reverse-axis current command value are limited.

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