JP2015171293A - Control device and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make power output from a power conditioner be close to a target power.SOLUTION: A control device according to an embodiment includes: a loss power determination unit for determining a loss power to be lost in transmitting power from a power generator to a converter on the basis of at least an impedance of a cable for transmitting power generated by the power generator to the converter; a rotation speed acquisition unit for acquiring a rotation speed of a rotor connected to the power generator, from the converter; and a torque command value determination unit that determines a torque command value on the basis of the rotation speed and the sum of the loss power and a target power value output by a power conditioner, and outputs the determined torque command value to the converter for controlling the power generator on the basis of the torque command value.

Description

  Embodiments described herein relate generally to a control device and a control method.

  In recent years, power generation systems using renewable energy have attracted attention. As a renewable energy power generation system, there is a power generation system using a fluid machine that is a device for converting energy between a fluid and a machine. Here, examples of the fluid machine include a turbo machine such as a water wheel or a windmill. A hydroelectric power generation system using a water turbine or a wind power generation system using a windmill can be operated in two ways: independent operation that operates independently without being connected to the grid, and grid-connected operation that operates while connected to the system. It is.

JP 2007-6553 A

  A generator coupled to a rotating body, a converter having an input end connected to the output end of the generator, a power conditioner (PCS) having an input end connected to the output end of the converter, and a control device for controlling the generator Assuming a power generation system comprising: In this power generation system, a generator and a converter are connected by a cable, and power loss occurs due to the impedance of the cable. The power loss varies depending on the difference in impedance depending on the length and thickness of the cable. If the power generation system controls the power at the output end of the generator to be the target power, the power output from the PCS is slightly lower than the target power of the generator due to power loss due to the cable impedance. I could not get the target power.

  In addition, if this power generation system has an instantaneous power outage during grid connection operation, the load decreases and the output voltage of the generator suddenly increases. Therefore, the control device suppresses the output voltage of the generator. During the momentary power failure, the power generated by the generator is reduced. As a result, the generated power of the generator is reduced until immediately before the instantaneous power failure return, and thus it takes time to return the generated power of the generator to the power generated before the instantaneous power failure after the instantaneous power failure recovery.

  The problem to be solved by the present invention makes it possible to bring the power output from the power conditioner closer to the target power, or to shorten the time for returning the generated power of the generator to the generated power before the momentary power interruption. A control device and a control method are provided.

  The control device according to the present embodiment determines the loss power that is lost when transmitting power from the generator to the converter based at least on the impedance of a cable that transmits power generated by the generator to the converter. A determination unit is provided. Furthermore, the control device includes a rotation speed acquisition unit that acquires the rotation speed of the rotating body connected to the generator from the converter. Further, the control device determines a torque command value based on the sum of the power loss, the target power value output by the power conditioner, and the rotation speed, and controls the generator based on the torque command value. A torque command value determination unit that outputs the torque command value to the converter is provided.

  The control device according to the present embodiment includes a DC voltage value acquisition unit that acquires a DC voltage value output from the converter to the power conditioner as a DC voltage value. Furthermore, the control device includes a proportional term determining unit that determines a proportional term based on a difference between a target voltage value of the DC voltage output from the converter and the DC voltage value. Furthermore, the control device includes an integral value determining unit that determines an integral value based on a difference between the target voltage value and the DC voltage value. Further, the control device determines a torque command value based on the proportional term and the integral value, and outputs the determined torque command value to the converter that controls the generated power based on the torque command value. A part. Furthermore, the control device includes an instantaneous power failure detection unit that detects an instantaneous power failure of a system to which the power conditioner is electrically connected based on a difference between the target voltage value and the DC voltage value. When the instantaneous power failure detection unit detects an instantaneous power failure, the integral value calculation unit maintains the integral value at the integral value before the instantaneous power failure.

FIG. 1 is a diagram illustrating a configuration of a power generation system 100 according to the first embodiment. FIG. 2 is a schematic diagram of an electrical connection relationship between the generator 2 and the converter 3. FIG. 3 is a diagram illustrating a configuration of the control device 5 according to the first embodiment. FIG. 4 is a graph showing an example of the relationship between the torque of the generator 2 and the rotational speed of the rotating body 1 in the hydroelectric power generation system. FIG. 5 is a diagram illustrating a configuration of a power generation system 100b according to the second embodiment. FIG. 6 is a diagram illustrating a configuration of the control device 5b according to the second embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating a configuration of a power generation system 100 according to the first embodiment. The power generation system 100 includes a rotating body 1, a generator 2 coupled to the rotating body 1, and a converter 3 having three inputs connected to three outputs of the generator by three cables. Furthermore, the power generation system 100 includes a power conditioner (PCS) in which two inputs are connected to two outputs of the converter 3 by cables, and a control device 5 electrically connected to the converter.

The rotating body 1 converts renewable energy into rotational energy. The rotating body 1 is, for example, a water wheel or a windmill, and converts a water flow or an air current into rotational energy.
The generator 2 converts the rotational energy converted by the rotating body 1 into electrical energy (AC power).

  Converter 3 acquires a torque command value from control device 5, adjusts the AC power generated by generator 2 based on the acquired torque command value, and converts the adjusted AC power into DC power. Converter 3 outputs a DC voltage to PCS 4 based on the converted DC power. Further, converter 3 measures the DC voltage output by itself and outputs a DC voltage value Vdc obtained by the measurement to control device 5. Converter 3 determines the number of rotations of rotating body 1. For example, the rotational speed of the rotating body 1 is determined from the output current and output voltage of the generator 2 using sensorless control. Converter 3 then outputs the determined rotational speed to control device 5.

The PCS 4 converts DC power into AC power and outputs the AC power to a system or a load.
In addition, the PCS 4 includes a changeover switch for switching between independent operation and grid interconnection operation, generates an independent / system interconnection switching signal according to an operation by the user of the switch, and generates the generated independent / system interconnection switching signal. Output to the control device 5. For example, when the PCS 4 is switched to the independent operation by the changeover switch, the independent / system interconnection switching signal is set to 0, and when it is switched to the grid interconnection operation by the changeover switch, the independent / system interconnection switching signal is set to 1. To do.

  The control device 5 acquires the rotational speed of the rotating body 1 and the DC voltage value Vdc from the converter 3 and acquires a self-sustained / system interconnection switching signal from the PCS 4. Then, the control device 5 determines a torque command value for commanding the torque of the generator 2 based on the acquired rotation speed, the DC voltage value Vdc, and the self-sustained / system interconnection switching signal. Then, control device 5 outputs the determined torque command value to converter 3 that controls the generated power based on this torque command value.

Next, the electrical connection relationship between the generator 2 and the converter 3 will be described with reference to FIG. FIG. 2 is a schematic diagram of an electrical connection relationship between the generator 2 and the converter 3. The generator 2 outputs a power generation unit GB, a first power generation end T1 that outputs first-phase AC power generated by the power generation unit GB, and a second phase that outputs second-phase AC power generated by the power generation unit GB. Power generation end T2 and a third power generation end T3 that outputs third-phase AC power generated by the power generation unit GB.
Furthermore, the generator 2 has a winding WW1 whose one end is electrically connected to the first power generation end T1, a winding WW2 whose one end is electrically connected to the second power generation end T2, and one end which is first. 3 power generation end T3 and a winding WW3 electrically connected.

The cable CB1 has one end connected to the other end of the winding WW1 and the other end connected to the first input of the converter.
Similarly, one end of the cable CB2 is connected to the other end of the winding WW2, and the other end is connected to the second input of the converter.
Similarly, the cable CB3 has one end connected to the other end of the winding WW3 and the other end connected to the third input of the converter.

  In the present embodiment, as an example, the resistances of the winding WW1, the winding WW2, and the winding WW3 all have the same resistance value R1. In the present embodiment, as an example, the cable CB1, the cable CB2, and the cable CB3 all have the same resistance value R2. Thereby, the resistance value from each power generation end of the generator 2 to each input end of the converter indicates R1 + R2. In particular, as the distance between the generator 2 and the converter 3 increases, the lengths of the cable cable CB1, the cable CB2, and the cable CB3 become longer, so that the resistance by the cable increases and the power loss in the cable increases.

Then, the structure of the control apparatus 5 which concerns on this embodiment is demonstrated using FIG. FIG. 3 is a diagram illustrating a configuration of the control device 5 according to the first embodiment.
The control device 5 includes a torque command value determination unit 50, a rotation speed acquisition unit 51, a DC voltage value acquisition unit 55, and a loss power determination unit 52. Here, the torque command value determination unit 50 includes a generator maximum torque value determination unit 53, an optimum torque value determination unit 54, and a control unit 56.

  The rotation speed acquisition unit 51 acquires the rotation speed of the rotating body 1 connected to the generator 2 from the converter 3. Then, the rotation speed acquisition unit 51 outputs the acquired rotation speed to the power loss determination unit 52, the optimum torque value determination unit 54, and the control unit 56.

  The loss power determining unit 52 loses when transmitting power from the generator 2 to the converter 3 based at least on the impedance R2 of any of the cables CB1 to CB3 that transmits the power generated by the generator 2 to the converter 3. Determine the power loss. In this embodiment, as an example, the power loss determination unit 52 includes the torque command value Tc determined by the control unit 56, the rotation speed acquired by the rotation speed acquisition unit 51, and the resistance value R1 of the winding WW1 of the generator 2. Then, the power loss is determined using the impedance R2 of the cable CB1. Thereby, the power loss due to the resistance of the winding WW1 of the generator 2 and the impedance of the cable CB1 can be determined.

  In the present embodiment, as an example, the power loss determination unit 52 uses the resistance value R1 of the winding WW1 and the impedance R2 of the cable CB1, but the resistance value R1 of the winding WW2 and the impedance R2 of the cable CB2 are used. Alternatively, the resistance value R1 of the winding WW3 and the impedance R2 of the cable CB3 may be used.

The loss power P _loss is expressed by the following equation (1), where P is the power generated by the generator.

P _loss = a1 × P + a2 (R1 + R2) Tc ² + a0 (1)

Here, a0 is a first constant based on the system characteristics, a1 is a second constant based on the system characteristics, and a2 is a constant based on the generator characteristics.
The generated power P of the generator is obtained by multiplying the torque of the generator and the angular frequency ω, and the torque of the generator is equal to the torque command value Tc. Therefore, the equation (1) is expressed by the following equation (2): It can be expressed as follows.

P _loss = a1 × Tc × ω + a2 (R1 + R2) Tc ² + a0 (2)

  The loss power determination unit 52 executes the calculation according to the equation (2). Here, the power loss determination unit 52 includes a multiplier 521, a multiplier 522, a multiplier 523, an adder 524, a multiplier 525, a multiplier 526, a multiplier 527, and an adder 528.

  Multiplier 521 calculates angular frequency ω by multiplying the rotational speed input from rotational speed acquisition unit 51 by 2π / 60, and outputs this angular frequency ω to multiplier 522.

  The multiplier 522 multiplies the torque command value Tc input from the control unit 56 and the angular frequency ω input from the multiplier 522 to calculate the generated power P, and uses the calculated generated power P for the control unit 56 and the multiplier. To 527.

  Multiplier 523 multiplies torque command values Tc with each other, and outputs a value t 1 after multiplication to multiplier 524.

  The adder 524 adds the resistance value R1 of the winding WW1 of the generator 2 and the impedance R2 of the cable CB1 and outputs the added value t2 to the multiplier 525.

  Multiplier 525 multiplies value t 1 input from multiplier 523 and value t 2 input from adder 524, and outputs the multiplied value t 3 to multiplier 526.

  The multiplier 526 multiplies the value t3 input from the multiplier 525 by the constant a2, and outputs the multiplied value t4 to the adder 528.

  The multiplier 527 multiplies the generated power P input from the multiplier 522 by a constant a1, and outputs the multiplied value t5 to the adder 528.

The adder 528 adds the value t4 input from the multiplier 526 and the value t5 input from the multiplier 527, and outputs the value after the addition to the generator maximum torque value determination unit 53 as the loss power P _loss. .

  The power loss determination unit 52 may determine power loss using the torque command value determined by the control unit 56, the rotation speed acquired by the rotation speed acquisition unit 51, and the impedance R2 of the cable CB1. . Thereby, the power loss due to the impedance R2 of the cable CB1 can be determined.

  The DC voltage value acquisition unit 55 acquires the value of the DC voltage output from the converter 3 to the PCS 4 as the DC voltage value Vdc from the converter 3. The DC voltage value acquisition unit 55 outputs the acquired DC voltage value Vdc to the control unit 56.

  The torque command value determination unit 50 determines a torque command value based on the power loss and the sum of the target power value output from the PCS 4 and the rotation speed, and generates the determined torque command value based on the torque command value. To the converter 3 that controls the machine 2. In the present embodiment, this target power value is, for example, a system maximum output value that is the maximum power that the generator 2 can output via the PCS 4. In the present embodiment, as an example, it is assumed that the rated power of the PCS 4 and the converter 3 is larger than the rated power of the generator 2. Therefore, the system maximum output value is, as an example, the rated power of the generator 2 ( Hereinafter, the maximum output value of the generator).

  The generator maximum torque value determination unit 53 adds the loss power determined by the loss power determination unit 52 and the generator maximum output value that is an example of the system maximum output value. Then, the generator maximum torque value determination unit 53 determines the generator maximum torque value based on the value after addition and the rotation number acquired by the rotation number acquisition unit 51. Since the value after the addition is obtained by adding the power loss due to the winding WW1 and the cable CB1 to the power generator maximum output value, the power generator maximum torque value is a torque value that is larger by this power loss. Thus, while the torque command value Tc is the generator maximum torque value, even if power is lost in the winding WW1 and the cable CB1, the output power of the PCS can be set as the target power.

  Here, the block in the generator maximum torque value determination part 53 represents the process mentioned above with the block diagram. The generator maximum torque value determination unit 53 includes an adder 531, a divider 532, and an output adjustment unit 533.

  The adder 531 adds the loss power and the system maximum output value, and outputs the value after the addition to the divider 532 as a corrected generator maximum output value.

  The divider 532 divides the corrected generator maximum output value input from the adder 531 by the angular frequency ω input from the multiplier 521, and uses the divided value as the generator maximum output limit torque value to the output adjustment unit 533. Output.

  The output adjustment unit 533 limits and outputs the generator maximum output limit torque value in a range from a preset lower limit value 0 to a generator allowable maximum torque Tq_lim that is an upper limit value. Specifically, the output adjustment unit 533 outputs 0 as the generator maximum torque value when the generator maximum output limit torque value is smaller than the lower limit value 0, and when it exceeds the generator allowable maximum torque Tq_lim, Torque Tq_lim is output as the generator maximum torque value, and when the lower limit value is 0 or more and the generator allowable maximum torque Tq_lim or less, the generator maximum output limit torque value is output as the generator maximum torque value. Here, the generator allowable maximum torque Tq_lim is a torque value of the generator 2 when the maximum current allowed by the generator 2 flows to the generator 2.

  The optimum torque value determination unit 54 determines a maximum torque limit optimum torque value whose upper limit is the generator maximum torque value, according to the rotation speed n acquired by the rotation speed acquisition unit 51. Here, the optimum torque value determination unit 54 includes a first function calculation unit 541 and an output adjustment unit 542.

  The first function calculation unit 541 calculates the rotation speed optimum torque value by using a first function f1 (n) that is a function of the rotation speed n. Here, the rotation speed optimum torque value is an optimum torque value according to the rotation speed, and is, for example, a linear function represented by a broken line W2 shown in FIG.

The output adjustment unit 542 calculates the rotation speed optimum torque value input from the first function calculation unit 541.
The output is limited within the range from the lower limit value 0 to the generator maximum torque value which is the upper limit value. Specifically, the output adjustment unit 542 outputs 0 as the maximum torque limit optimum torque value when the rotation speed optimum torque value is smaller than the preset lower limit value 0, and the generator maximum value input from the output adjustment unit 533 is output. When the torque value is exceeded, the generator maximum torque value is output as the maximum torque limit optimum torque value. When the rotation speed optimum torque value is in the range from 0 to the generator maximum torque value, the output adjustment unit 542 outputs the rotation speed optimum torque value as it is as the maximum torque limit optimum torque value.

  Here, the maximum torque limit optimum torque value changes according to the rotational speed, for example, as a curve W1 shown in FIG.

  FIG. 4 is a graph showing an example of the relationship between the torque of the generator 2 and the rotational speed of the rotating body 1 in the hydroelectric power generation system. A curve W1 is a curve showing the maximum torque limit optimum torque value that changes according to the rotation speed n. Curves L1 to L16 indicate the relationship between the torque of the generator 2 and the rotational speed of the rotating body 1 each time the flow rate of water increases from 1 m / s in increments of 0.2 m / s. As shown by the curves L1 to L16 in FIG. That is, the maximum torque changes according to each flow velocity. The first function f1 (n) represented by the straight line of the broken line W2 is a linear function approximated by the least square method using the rotation speed and the torque coordinates that take the maximum value of torque at each flow velocity.

In the present embodiment, the torque command value of the generator is determined according to the first function f1 (n) represented by the straight line of the broken line W2, as indicated by the curve W1 in the section from the rotational speed n1 to n2 in FIG. Is done.
As indicated by the curve W1 in the section from the rotation speed n2 to n3 in FIG. 4, the generator torque command value is fixed to the generator allowable maximum torque Tq_lim by the output adjustment unit 533.

  As indicated by the curve W1 in the section from the rotational speed n3 to n4 in FIG. 4, the torque command value Tc of the generator is expressed by the following equation (3).

Tc = (Pm + _Ploss ) / (2πn / 60) = (Pm + _Ploss ) / ω (3)

  As described above, in the section from the rotational speed n3 to n4 in FIG. 4, the torque command value Tc of the generator is the sum of the rated power (generator maximum output value) Pm of the generator and the loss power, and the current rotational speed. It is expressed by a value divided by the current angular frequency ω calculated from n.

  The generator maximum torque value determining unit 53, as shown in the equation (3), sets the generator maximum output limit torque value as the sum of the generator maximum output value Pm and the power loss in the winding WW1 and the cable CB1 as an angular frequency. Divide by ω. By doing in this way, the generator 2 outputs alternating current power with the electric power value which added the loss electric power in winding WW1 and cable CB1 to the generator maximum output value Pm. Thereby, even if power is consumed in winding WW1 and cable CB1, converter 3 can receive AC power of generator maximum output value Pm, and outputs DC power of generator maximum output value Pm to PCS4. be able to. For this reason, the PCS 4 can output AC power of the generator maximum output value Pm to the system.

  Based on the difference between the target voltage value Vdc_ref of the DC voltage output from converter 3 and DC voltage value Vdc, control unit 56 determines a torque command value whose upper limit is the maximum torque limit optimum torque value, and determines the determined torque command The value is output to the converter 3 that controls the generator 2 based on the torque command value.

Here, the control unit 56 includes a subtractor 561, a proportional term determination unit PT, an integral value determination unit IT, and an output unit OT.
The subtractor 561 subtracts the DC voltage value Vdc acquired by the DC voltage value acquisition unit from the target voltage value Vdc_ref, and subtracts the difference ΔV (= Vdc_ref−Vdc) obtained by the proportional term determination unit PT and the integral value determination. Output to the section IT.

  The proportional term determining unit PT determines the proportional term based on the difference ΔV between the preset target voltage value Vdc_ref and the DC voltage value Vdc acquired by the DC voltage value acquiring unit 55.

  The integral value determining unit IT determines an integral value based on the difference between the target voltage value Vdc_ref and the DC voltage value Vdc.

  The output unit OT determines a torque command value based on the proportional term and the integral value, and outputs the determined torque command value to the converter 3 that controls the generated power based on the torque command value.

Hereinafter, the structure of each part which comprises the control part 56 is demonstrated.
The proportional term determining unit PT includes a multiplier PT1, a multiplier PT2, and a multiplier PT3.
The multiplier PT1 multiplies the difference ΔV input from the subtractor 561 by a proportional gain Kp to calculate a proportional calculation output value, and outputs the calculated proportional calculation output value to the multiplier PT3.
The multiplier PT2 calculates a proportional gain correction output value by multiplying the rotation speed n input from the rotation speed acquisition unit 51 by the proportional correction gain, and outputs the calculated proportional gain correction output value to the multiplier PT3.
The multiplier PT3 multiplies the proportional calculation output value input from the multiplier PT1 and the proportional gain correction output value input from the multiplier PT2 to calculate the proportional term, and the calculated proportional term is output to the proportional calculation correction output. The value is output to the output unit OT.

  The integral value determining unit IT includes an integral gain correcting unit IT1, an integral input value determining unit IT12, a subtractor IT3, an integrating unit IT4, and a subtractor IT6.

  The integral gain correction unit IT1 uses the generated power P input from the multiplier 522 as an argument when the self-sustained / system interconnection switching signal input from the PCS 4 is 1, that is, in the system interconnection operation. The value of f2 (P) is output to the integral input value determining unit IT12 as the integral gain correction value Kir. On the other hand, the integral gain correction unit IT1 outputs 0 as the integral gain correction value Kir to the integral input value determination unit IT12 when the independent / system interconnection switching signal input from the PCS 4 is 0, that is, in the independent operation. .

  The integral input value determination unit IT12 calculates the value of the third function f3 (ΔV, Kir) using the difference ΔV input from the subtractor 561 and the integral gain correction value Kir input from the integral gain correction unit IT1 as arguments. The calculated value is output to the subtractor IT3 as an integral input value. Here, for example, when the integral gain is Ki, the third function f3 (ΔV, Kir) = ΔV × Ki × Kir is represented.

  The subtractor IT3 subtracts the integrated torque limit excess value input from the subtractor IT6 from the integrated input value input from the integral input value determining unit IT12, and outputs the value after the subtraction to the integrating unit IT4. The integral torque limit excess value is a value obtained when the integral value exceeds the maximum torque limit optimum torque value. If the integral value exceeds the maximum torque limit optimum torque value by subtracting this integral torque limit excess value from the integral input value by the subtractor IT3, the integral input that is input to the integration unit IT4 by the excess amount. Decrease the value. Thereby, when the integral value becomes too large, the integral value can be lowered in a short time.

  The integration unit IT4 integrates the integration input value with respect to time, and outputs the value after integration as the integration value. As an example, the integration unit IT4 holds the previous integration value, which is the integration value output by itself, and calculates the integration value by adding the previous integration value to the value input from the subtractor IT3. The integration unit IT4 outputs the calculated integration value to an output adjustment unit OT1 and a subtractor IT6 described later of the output unit OT. The processing by the integration unit IT4 is, for example, processing for multiplying a value input from the subtractor IT3 by a transfer function 1 / Ts (T is an integration period, s is a complex number).

  The subtractor IT6 subtracts the integral calculation output value input from the output adjustment unit OT1 from the integral value input from the integration unit IT4 to calculate an integral torque limit excess value, and subtracts the integral torque limit excess value from the subtractor IT3. Output to.

  The output unit OT includes an output adjustment unit OT1, an adder OT2, and an output adjustment unit OT3.

  The output adjustment unit OT1 limits the integral value within a range from a preset lower limit value 0 to a maximum torque limit optimum torque value that is an upper limit value, and outputs the integral value to the subtractor IT6 and the output unit OT as an integral calculation output value. To do. Specifically, the output adjustment unit OT1 outputs 0 when the integral value is smaller than the lower limit value 0, and outputs the maximum torque limit optimum torque value when the integral value exceeds the maximum torque limit optimum torque value. Is less than the lower limit value 0 and less than the maximum torque limit optimum torque value, the integral value is output as it is.

  The adder OT2 calculates a torque value by adding the proportional gain correction output value input from the multiplier PT3 and the integral calculation output value input from the output adjustment unit OT1, and outputs the calculated torque value to the output adjustment unit. Output to OT3.

  The output adjustment unit OT3 limits the torque value input from the adder OT2 within a range from a preset lower limit value 0 to a maximum torque limit optimum torque value that is an upper limit value, and a multiplier 522 as a torque command value. And output to the converter 3. Specifically, the output adjustment unit OT3 outputs 0 when the torque value is smaller than the lower limit value 0, and outputs the maximum torque limit optimum torque value when the torque value exceeds the maximum torque limit optimum torque value. Is less than the lower limit value 0 and less than the maximum torque limit optimum torque value, the torque value is output as it is.

(Description of operation)
Next, operations of the power generation system 100 and the control device 5 will be described.
In the power generation system 100 illustrated in FIG. 1, the rotating body 1 is rotated by renewable energy such as a water flow or an air flow. Due to this rotation, the generator 2 generates an alternating voltage. Converter 3 converts this AC voltage into a DC voltage and outputs it to PCS 4.

  In addition, converter 3 outputs the rotational speed of generator 2 and DC voltage value Vdc, which is the value of the DC voltage output by converter 3, to control device 5 at a predetermined cycle. Control device 5 determines a torque command value based on the rotational speed and DC voltage value Vdc, and outputs the determined torque command value to converter 3. Converter 3 controls generator 2 based on this torque command value. Specifically, the converter 3 controls the current output from the generator 2 so that the torque of the generator 2 becomes this torque command value.

When the DC voltage value Vdc exceeds a preset power generation output possible voltage value Vdc_pcs, the PCS 4 outputs AC power to the system or a self-supporting load.
PCS 4 is in a standby state until the value of the DC voltage input from converter 3 reaches power generation output possible voltage value Vdc_pcs. Therefore, the control device 5 increases the torque command value until the DC voltage reaches the power generation output possible voltage value Vdc_pcs. Here, the target voltage value Vdc_ref is set so that Vdc_ref> Vdc_pcs, that is, the target voltage value Vdc_ref exceeds the power generation output possible voltage value Vdc_pcs.

  The power generation system 100 according to the present embodiment has two operation modes: a grid connection operation mode for supplying generated power to the system, and a self-sustaining operation mode for directly supplying power to a load connected to the PCS 4. The PCS 4 can switch modes. Hereinafter, the operation in each operation mode will be described.

  First, the operation in the grid interconnection operation mode will be described. When the DC voltage value Vdc exceeds the power generation output possible voltage value Vdc_pcs, the PCS 4 starts outputting AC power to the system. At that time, the PCS 4 controls the DC voltage value Vdc to be the power generation output possible voltage value Vdc_pcs.

  On the other hand, the control device 5 tries to control the generator 2 so that the DC voltage value Vdc becomes the target voltage value Vdc_ref, but the DC voltage value Vdc is obtained by the voltage control of the PCS 4 connected to a stable system. The power generation output possible voltage value Vdc_pcs. For this reason, since Vdc_ref> Vdc_pcs is set, the difference ΔV (= Vdc_ref−Vdc) obtained by subtracting the DC voltage value Vdc from the target voltage value Vdc_ref is always a constant positive value during the grid connection operation. Become. Due to this constant positive value, the torque value input to the output adjustment unit OT3 always exceeds the maximum torque limit optimum torque value. For this reason, during the grid interconnection operation, the torque command value is always the maximum torque limit optimum torque value.

  Thus, in the grid interconnection operation mode, when the PCS 4 shifts from the standby state to the grid interconnection operation, the control device 5 determines the torque indicated by the curve W1 in FIG. 4 from the control of the torque command value by the PI control. The control shifts to a control in which the maximum torque limit optimum torque value having the rotational speed relationship becomes the torque command value.

  Subsequently, the operation in the self-sustaining operation mode will be described. When the DC voltage value Vdc exceeds the power generation output possible voltage value Vdc_pcs, the PCS 4 starts outputting AC power to the self-supporting load. At this time, unlike the grid-connected operation mode, the PCS 4 does not supply power to the system, so that the control device 5 performs control to keep the DC voltage value Vdc constant at the target voltage value Vdc_ref.

  Thereby, in the self-sustained operation mode, even when the connected load varies, the control device 5 controls the DC voltage value to be the target voltage value Vdc_ref larger than the power generation output possible voltage value Vdc_pcs. Stable autonomous operation is possible.

  As described above, in the first embodiment, the control device 5 generates power from the generator 2 to the converter based on at least the impedance of any of the cables CB1 to CB3 that transmits the power generated by the generator 2 to the converter 3. A loss power determining unit 52 that determines a loss power that is lost during transmission is provided. Furthermore, the control device 5 includes a rotation speed acquisition unit 51 that acquires the rotation speed of the rotating body connected to the generator 2 from the converter 3. Further, the control device 5 determines a torque command value based on the sum of the power loss and the target power value output by the PCS 4 and the rotational speed, and the converter 3 controls the generator 2 based on the torque command value. Further, a torque command value determining unit 50 for outputting the torque command value is provided.

  Thereby, the torque command value determination unit 50 sets the torque command value to a value obtained by adding the loss power in the cable CB1 to the target power value, so that the generator 2 adds the loss power in the cable CB1 to the target power value. The value is output. Thereby, even if power is consumed in the cable CB1, the converter 3 can receive the AC power having the target power value, and can output the DC power having the target power value to the PCS 4. For this reason, PCS4 can output the alternating current power of a target electric power value. As a result, the value of power output from the PCS 4 can be brought close to the target power value.

  For example, the power loss determination unit 52 determines the power loss using the torque command value determined by the torque command value determination unit 50, the rotation speed acquired by the rotation speed acquisition unit 51, and the impedance of the cable CB1. . As a result, the generator 2 outputs power that is larger than the target power value by the loss power in the cable CB1, so even if power is lost in the cable CB1, the converter 3 outputs power that is close to the target power value. be able to. For this reason, the power close to the target power value can be output from the PCS 4.

  In the present embodiment, the power loss determining unit 52 further determines power loss using the resistance value of the winding WW1 of the generator 2. As a result, the generator 2 outputs power larger than the target power value by the loss power in the winding WW1 and the cable CB1, so even if power is lost in the winding WW1 and the cable WW1, the converter 3 outputs the target power. Electric power that is closer to the electric power value can be output. For this reason, the power further closer to the target power value can be output from the PCS 4.

  The power loss determination unit 52 according to the present embodiment uses the torque command value determined by the torque command value determination unit 50, the rotation speed acquired by the rotation speed acquisition unit 51, and the impedance of the cable CB1. Although the power loss was determined, it is not limited to this. Instead, the lost power determination unit 52 may determine the lost power using the current value of the current output from the generator 2 and the impedance R2 of the cable CB1. At that time, the loss power calculation unit may further determine the loss power using the resistance value R1 of the winding of the generator 2. Specifically, the loss power determination unit 52 may determine I × (R1 + R2) as the loss power, where I is the current value of the current output from the generator 2.

(Second Embodiment)
Next, the second embodiment will be described. In the control device according to the second embodiment, when an instantaneous power failure is detected, the integral value calculation unit maintains the integral value at the integral value before the instantaneous power failure. This prevents a decrease in the torque command value during a momentary power failure, thus preventing a decrease in the power generation output from the generator 2 during the momentary power failure. Can be restored.

  Hereinafter, the configuration of the power generation system 100b according to the second embodiment will be described. The configuration of the power generation system 100b according to the second embodiment is a configuration in which the control device 5 is changed to the control device 5b as compared with the configuration of the power generation system 100 according to the first embodiment shown in FIG. ing. Elements common to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

Next, the configuration of the control device 5b according to the second embodiment will be described. FIG. 6 is a diagram illustrating a configuration of the power generation system 100 according to the second embodiment.
The control device 5b according to the second embodiment includes a rotation speed acquisition unit 51, a multiplier 521, a generator maximum torque value determination unit 53b, an optimum torque value determination unit 54, a DC voltage value acquisition unit 55, a control unit 56b, and A switching signal generator 57 is provided. In addition, the same code | symbol is attached | subjected to the element which is common in FIG. 3, and the specific description is abbreviate | omitted.

The multiplier 521 calculates the angular frequency ω by multiplying the rotational speed acquired by the rotational speed acquisition unit 51 by 2π / 60, and uses the calculated angular frequency ω as the generator maximum torque value determination unit 53b and the integral value determination unit ITb. Output to.
The generator maximum torque value determination unit 53 b includes a divider 532 and an output adjustment unit 533.
The divider 532 according to the first embodiment calculates the system maximum output limit torque value by dividing the sum of the system maximum output value and the loss power by the angular frequency ω input from the multiplier 521. On the other hand, the divider 532 according to the second embodiment is different in that the system maximum output limit torque value is calculated by dividing the system maximum output value by the angular frequency ω input from the multiplier 521.

The switching signal generator 57 generates an integral input value switching signal used for switching the integral input value input to the subtractor IT3 of the integral value determiner ITb.
Here, the switching signal generation unit 57 includes an instantaneous power failure detection unit 571, an instantaneous power failure recovery detection unit 572, a timer unit 573, an OR operation unit 574, and a switching signal generation unit 575.
The instantaneous power failure detection unit 571 detects an instantaneous power failure of the system to which the PCS 4 is electrically connected based on a difference between a preset target voltage value and a DC voltage value. Specifically, for example, the instantaneous power failure detection unit 571 detects an instantaneous power failure when the difference between the target voltage value and the DC voltage value is less than the first threshold value. When the instantaneous power failure detection unit 571 detects an instantaneous power failure, the output signal output to the switching signal generation unit 575 is set to a high level only for a predetermined period. In other cases, the instantaneous power failure detection unit 571 sets the output signal to a low level.

The instantaneous power failure recovery detection unit 572 detects the recovery from the instantaneous power failure based on the difference between the target voltage value and the DC voltage value. Specifically, for example, the instantaneous power failure recovery detection unit 572 has a difference between the target voltage value and the DC voltage value that exceeds a second threshold value (for example, −350 V) that is greater than the first threshold value (for example, −400 V). In the case, the return from the instantaneous power failure is detected.
When the instantaneous power failure return detection unit 572 detects the return from the instantaneous power failure, the output signal output to the OR operation unit 574 is set to the high level for a predetermined period. In other cases, the instantaneous power failure return detection unit 572 sets the output signal to a low level.

  The timer unit 573 outputs an output signal to be output to the OR operation unit 574 when the integral input value switching signal output from the switching signal generation unit 575 becomes a high level, that is, when a predetermined time has elapsed since the momentary power failure occurred. Keep it high for the period. In other cases, the timer unit 573 sets the output signal to a low level.

  The OR operation unit 574 outputs an output signal to be output to the switching signal generation unit 575 when at least one of the output signal input from the instantaneous power failure recovery detection unit 572 or the output signal input from the timer unit 573 is high level. Set to high level for a predetermined period. In other cases, the OR operation unit 574 sets the output signal to a low level.

  The switching signal generation unit 575 generates an integral input value switching signal based on the output signal from the instantaneous power failure detection unit 571 and the output signal from the OR operation unit 574, and determines the integrated input value switching signal thus generated as an integral value. The data is output to the switching unit IT8 (to be described later) of the unit IT. Here, the switching signal generation unit 575 is, for example, an SR latch having an input port S, an input port R, and an output port Q. Here, S means “Set” and R means “Reset”. An output signal from the instantaneous power failure detection unit 571 is input to the input port S, an output signal from the OR operation unit 574 is input to the input port R, and an integral input value switching signal is output from the output port Q. .

  When the output signal from the instantaneous power failure detection unit 571, that is, the input port S is high level, and the output signal from the OR operation unit 574, that is, the input port R is low level, the integral input value switching signal is set to high level. On the other hand, when the output signal from the instantaneous power failure detection unit 571, that is, the input port S is at a low level and the output signal from the OR operation unit 574, that is, the input port R is at a high level, the switching signal generation unit 575 Set to low level. Further, when the output signal from the instantaneous power failure detection unit 571, that is, the input port S is low level, and the output signal from the OR operation unit 574, that is, the input port R is low level, the integral input value switching signal is maintained at the previous level. To do.

The configuration of the control unit 56b according to the second embodiment is such that the integral value determining unit IT is changed to an integral value determining unit ITb as compared with the configuration of the control unit 56 according to the first embodiment. .
When the instantaneous power failure detection unit 571 detects an instantaneous power failure, the integral value determination determining unit ITb maintains the integrated value at the integral value before the instantaneous power failure. Here, the integral value determining unit ITb according to the second embodiment is different from the integral value determining unit IT according to the first embodiment in that a multiplier IT7 and a switching unit IT8 are added.

  The multiplier IT7 calculates the generated power by multiplying the angular frequency ω input from the multiplier 521 by the torque command value input from the output adjustment unit OT3, and outputs the calculated generated power to the integral gain correction unit IT1. To do.

The switching unit IT8 switches the integral input value to be output between a value based on the difference ΔV between the target voltage value and the DC voltage value and 0.
Specifically, when the integral input value switching signal input from the switching signal generation unit 575 changes from the low level to the high level, the switching unit IT8 detects the instantaneous power failure, and therefore sets the output integral input value to 0. Switch to. While the integral input value switching signal is at the high level, the switching unit IT8 keeps the integral input value to be output as 0. As a result, the integral value output by the integration unit IT4 is fixed to the integral value in the previous clock, and thus the integral value is maintained at the integral value immediately before the instantaneous power failure.

On the other hand, when the integral input value switching signal input from the switching signal generation unit 575 changes from the high level to the low level, that is, the switching unit IT8 returns from the momentary power interruption or when a predetermined time has elapsed since the momentary power interruption. The integral input value to be output is switched to the value output by the integral input value determining unit IT2. That is, the switching unit IT8 switches the output integral input value to a value based on the difference ΔV between the target voltage value and the DC voltage value. While the integral input value switching signal is at the low level, the switching unit IT8 keeps the output integral input value based on the difference ΔV between the target voltage value and the DC voltage value.
In this way, the integral value determining unit ITb allows the difference ΔV between the target voltage value and the DC voltage value and the instantaneous power failure that has been maintained when the instantaneous power failure recovery detection unit 572 detects the recovery from the instantaneous power failure. The integral value is determined based on the previous integral value.

  The integration unit IT4 integrates the integration input value output from the switching unit IT8 over time, and outputs the value after integration as the integration value. As an example, the integration unit IT4 holds the previous integration value that is the integration value output by itself last time, and calculates the integration value by adding the previous integration value to the integration input value input from the switching unit IT8.

(Operation of the control device 5b)
Hereinafter, the operation of the control device 5b according to the second embodiment will be described. When an instantaneous power failure occurs, the instantaneous power failure detection unit 571 detects the instantaneous power failure by a change in the difference ΔV between the target voltage value and the DC voltage value, and the switching signal generation unit 575 generates a high-level integral input value switching signal. Output. Thereby, the switching unit IT8 fixes the output integral value to 0, and the integrating unit IT4 continues to output the integral value immediately before the momentary power interruption.

  When the instantaneous power failure recovery detection unit 572 detects the recovery from the instantaneous power failure due to the change in the difference ΔV between the target voltage value and the DC voltage value, or when the timer unit 573 measures the elapse of a predetermined time from the time of the instantaneous power failure occurrence, The switching signal generator 575 outputs a low-level integral input value switching signal. Thereby, the switching unit IT8 switches the output integral value to the output value of the integral input value determining unit IT2, and resumes the normal integration operation based on the difference ΔV between the target voltage value and the DC voltage value.

  As described above, the control device 5b according to the second embodiment includes the DC voltage value acquisition unit 55 that acquires the DC voltage value output from the converter 3 to the PCS 4 as the DC voltage value. Furthermore, control device 5b includes a proportional term determining unit PT that determines a proportional term based on a difference ΔV between the target voltage value of the DC voltage output from converter 3 and the DC voltage value. Furthermore, the control device 5b includes an integral value determining unit ITb that determines an integral value based on the difference ΔV between the target voltage value and the DC voltage value. Furthermore, control device 5b determines a torque command value based on the proportional term and the integral value, and outputs the determined torque command value to converter 3 that controls the generated power based on the torque command value. An output unit OT is provided. Furthermore, the control device 5b includes an instantaneous power failure detection unit 571 that detects an instantaneous power failure of the system to which the PCS 4 is electrically connected based on the difference between the target voltage value and the DC voltage value. When the instantaneous power failure detection unit 571 detects an instantaneous power failure, the integral value determination determination unit ITb maintains the integrated value at the integral value before the instantaneous power failure.

  Thereby, when a momentary power failure occurs, the torque command value is maintained at the torque command value before the power failure by maintaining the integral value at the integral value before the power failure. For this reason, the fall of the power generation output of the generator 2 during a momentary power failure can be prevented, and the power generation output of the power generator 2 can be quickly returned to the power generation output before the momentary power failure after returning from the power failure.

  Furthermore, the control device 5b includes a timer unit 573 that determines whether or not a predetermined time has elapsed since the instantaneous power failure detection unit 571 detected the instantaneous power failure. Then, when it is determined that the predetermined time has elapsed by the timer unit 573, the integral value determining unit ITb is based on the difference ΔV between the target voltage value and the DC voltage value and the integral value that was maintained before the instantaneous interruption. The integral value is determined.

  As a result, the integral value can be maintained at the integral value before the momentary interruption until a predetermined time has elapsed since the momentary interruption occurred. For this reason, for example, when the output of the converter 3 is connected not only to the PCS 4 but also to the load, it is possible to prevent a reduction in the power supplied to the load until a predetermined time has elapsed since the momentary power failure occurred.

The integral value determination unit IT determines an integral value obtained by integrating a value based on the difference ΔV between the target voltage value and the DC voltage value, and when the instantaneous power failure detection unit 571 detects an instantaneous power failure, Is stored, and when the instantaneous power failure recovery detection unit 572 detects the recovery from the instantaneous power failure, the current integrated value is updated with the stored integral value.
Thereby, at the time of instantaneous power failure recovery, the integrated value is updated with the integral value determined before the instantaneous power failure, so that the torque command value before the instantaneous power failure is set at the time of instantaneous power failure recovery. For this reason, the power generation output of the generator 2 can be promptly returned to the power generation output before the instantaneous power failure after returning from the instantaneous power failure.

  A program for executing each process of the control device of each embodiment is recorded on a computer-readable recording medium, the program recorded on the recording medium is read into a computer system, and executed by a processor. The various processes described above according to the control device of each embodiment may be performed.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

100, 100b Power generation system 1 Rotating body 2 Generator 3 Converter 4 PCS
5, 5b Control device GB Power generation unit T1 First power generation end T2 Second power generation end T3 Third power generation end WW1, WW2, WW3 Winding CB1, CB2, CB3 Cable 50 Torque command value determination unit 51 Rotation speed acquisition unit 52 Power Loss Determination Unit 521 Multiplier 522 Multiplier 523 Multiplier 524 Adder 525 Multiplier 526 Multiplier 527 Multiplier 528 Adder 53, 53b Generator Maximum Torque Value Determining Unit 531 Adder 532 Divider 533 Output Adjusting Unit 54 Optimal torque value determination unit 541 First function calculation unit 542 Output adjustment unit 55 DC voltage value acquisition unit 56, 56b Control unit PT proportional term determination unit PT1 multiplier PT2 multiplier PT3 multiplier IT, ITb integration value determination unit IT1 integration Gain correction unit IT2 Integration input value determination unit IT3 Subtractor IT4 Integration unit IT6 Subtractor IT Multiplier IT8 switching unit OT output unit OT1 output adjusting unit OT2 adder OT3 output adjusting section 57 switching signal generator 571 the instantaneous blackout detecting section 572 instantaneous blackout restoration detection unit 573 the timer unit 574 OR arithmetic unit 575 the switching signal generating unit

Claims (14)

A loss power determination unit that determines a loss power to be lost when transmitting power from the generator to the converter based at least on an impedance of a cable that transmits power generated by the generator to the converter;
A rotational speed acquisition unit that acquires the rotational speed of the rotating body connected to the generator from the converter;
A torque command value is determined based on the sum of the power loss and the target power value output by the power conditioner and the rotational speed, and the torque is controlled by the converter that controls the generator based on the torque command value. A torque command value determination unit for outputting a command value;
A control device comprising: The power loss determination unit determines the power loss using the torque command value determined by the torque command value determination unit, the rotation speed acquired by the rotation speed acquisition unit, and the impedance of the cable. The control apparatus according to 1. The control device according to claim 1, wherein the loss power determination unit determines the loss power using a current value of a current output from the generator and an impedance of the cable. The control device according to claim 2, wherein the loss power calculation unit further determines the loss power using a resistance value of a winding of the generator. The control device according to any one of claims 1 to 4, wherein the target power value is a system maximum output value that is a maximum power that the generator can output via the power conditioner. The converter further includes a DC voltage value acquisition unit that acquires the DC voltage value output from the converter as a DC voltage value to the power conditioner,
The torque command value determination unit
The power generation for determining the generator maximum torque value based on the value after the addition and the rotation speed acquired by the rotation speed acquisition section by adding the power loss determined by the power loss determination section and the target power value A machine maximum torque value determination unit;
An optimum torque value determination unit that determines a maximum torque limit optimum torque value with the generator maximum torque value as an upper limit according to the rotation number acquired by the rotation number acquisition unit;
A control unit that determines the torque command value with the maximum torque limit optimum torque value as an upper limit based on a difference between a target voltage value of the DC voltage output by the converter and the DC voltage value;
With
The target voltage value is set to be larger than a power generation output possible voltage value that is a target voltage when the power conditioner controls the DC voltage during grid connection. The control device according to item. A step of determining a loss power lost when transmitting power from the generator to the converter based on at least an impedance of a cable that transmits power generated by the generator to the converter;
A step of acquiring a rotational speed of a rotating body connected to the generator from the converter;
A torque command value determining unit determines a torque command value based on the sum of the power loss and the target power value output by the power conditioner and the rotation speed, and controls the generator based on the torque command value. Outputting the torque command value to the converter;
A control method. A DC voltage value acquisition unit that acquires the value of the DC voltage that the converter outputs to the power conditioner as a DC voltage value from the converter;
A proportional term determining unit that determines a proportional term based on a difference between a target voltage value of the DC voltage output by the converter and the DC voltage value;
Based on the difference between the target voltage value and the DC voltage value, an integral value determining unit that determines an integral value;
An output unit that determines a torque command value based on the proportional term and the integral value, and outputs the determined torque command value to the converter that controls generated power based on the torque command value;
Based on the difference between the target voltage value and the DC voltage value, an instantaneous power failure detection unit that detects an instantaneous power failure of a system to which the power conditioner is electrically connected;
With
The said integral value calculation part maintains the said integral value in the said integral value before a momentary stop, when the said momentary stop detection part detects a momentary stop Control apparatus. Based on the difference between the target voltage value and the DC voltage value, further comprising an instantaneous blackout return detection unit for detecting return from the instantaneous blackout,
The integral value determining unit, when the instantaneous power failure recovery detecting unit detects a recovery from the instantaneous power failure, the difference between the target voltage value and the DC voltage value, and the integrated value before the instantaneous power failure that has been maintained. The control device according to claim 8, wherein the integral value is determined based on the control value. When the difference between the target voltage value and the DC voltage value is less than a first threshold, the instantaneous power failure detection unit detects the instantaneous power failure,
The instantaneous power failure recovery detection unit detects recovery from the instantaneous power failure when a difference between the target voltage value and the DC voltage value exceeds a second threshold value that is greater than the first threshold value. The control device described. A timer unit for determining whether a predetermined time has elapsed since the momentary power failure detection unit detected a momentary power failure;
The integral value determining unit, based on the difference between the target voltage value and the DC voltage value, and the maintained integral value before the instantaneous power failure when the timer unit determines that a predetermined time has elapsed. The control device according to claim 8, wherein the integral value is determined. The integral value determination unit includes:
A switching unit that switches an integral input value to be output between a value based on a difference between the target voltage value and the DC voltage value and 0;
Integrating the integration input value output by the switching unit over time, an integration unit outputting the value after integration as the integration value;
With
When the instantaneous power failure detection unit detects an instantaneous power failure, the switching unit switches the output integral input value to 0, and when the instantaneous power failure recovery detection unit detects a return from the instantaneous power failure, the switching unit The control device according to claim 9 or 10, wherein an integral input value to be output is switched to a value based on a difference between the target voltage value and the DC voltage value. Based on the difference between the target voltage value and the DC voltage value, further comprising an instantaneous blackout return detection unit for detecting return from the instantaneous blackout,
The integral value determining unit determines an integral value obtained by integrating a value based on a difference between the target voltage value and the DC voltage value;
The integral value determination unit stores the integral value determined before the instantaneous power failure when the instantaneous power failure detection unit detects a momentary power failure, and the instantaneous power failure return detection unit detects a return from the instantaneous power failure. The control device according to claim 8, wherein the current integrated value is updated with the stored integrated value. A DC voltage value acquisition unit acquires from the converter a DC voltage value output from the converter to the power conditioner as a DC voltage value;
A proportional term determining unit determining a proportional term based on a difference between the target voltage value and the DC voltage value;
An integral value determining unit determining an integral value based on a difference between the target voltage value and the DC voltage value;
An output unit determines a torque command value based on the proportional term and the integral value, and outputs the determined torque command value to the converter that controls the generated power based on the torque command value;
A step of detecting a momentary power failure of a system to which the power conditioner is electrically connected based on a difference between the target voltage value and the DC voltage value;
When the integral value calculation unit detects the instantaneous power failure when the instantaneous power failure detection unit detects the instantaneous power failure, maintaining the integral value at the integral value before the instantaneous power failure; and
A control method.

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