JPH09271176A - Power-system linked inverter device, and waveform generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the harmonic components of a sine wave current of a power-system linked power converting means, by generating the output voltage command value of the power converting means so as to add to it the correcting quantity for correcting the originating raising or lowering portion of an actual power system voltage from a control delay time generated in the term extending from the sensing of the AC power system voltage to the outputting of the power converting means voltage. SOLUTION: A correcting means 23 for generating a correcting quantity >=V output a carrying portion of a power system voltage Vs as the correction quantity >=V. The varying portion ΔV occurs in the term extending from the time when the phase of a commercial AC power system 2 is sensed until a power converting circuit 3 outputs a voltage obtained as an output voltage reference. That is, the correcting means 23 has both a phase leading means 24 for leading by θ/2 the phase of a normalized sine wave signal S2 whose phase and period are sensed from the power system voltage Vs and which is in phase with the voltage Vs and a sampling-time outputting means 25. The correcting quantity ΔV is added to the instantaneous value Vs of the power system voltage toe obtain a corrected command value Vs * of the power system voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grid interconnection inverter device and a waveform generator for converting direct current power such as solar power generation and biogas power generation into alternating current power and connecting the system to an alternating current power system to supply power. It relates to the device.

[0002]

2. Description of the Related Art An example of a grid interconnection inverter device of this type is one in which DC power generated by a solar cell is converted into AC power by a grid interconnection inverter device to supply power to a load together with an AC power system. There is. The power generated by the solar cell is normally consumed by the load, but if there is surplus power, it is transmitted to the AC power system (reverse power flow). Power is supplemented.

In a conventional grid-connected inverter device, for example, as shown in FIG. 13, a DC power generated by a solar cell is converted into AC power by a power conversion circuit 100, and the AC power is supplied to a filter 101 and a transformer 102. The power is supplied to the AC power system 103 via the AC power system 103. In this system interconnection inverter device, the system voltage of the AC power system 103 is detected by the instrument transformer 104, and the sine wave signal Vs (sinω) having no phase with respect to the system voltage is detected via the filter circuit 105.
t) is formed and input to the control means. The control means multiplies this sine wave signal Vs by a fixed amount of current amplitude reference value Im * corresponding to the maximum current value by the multiplier 106 to obtain the current reference value I *.

The current reference value I * is compared with the current detection value Is detected by the current transformer 107 connected to the output side of the power conversion circuit 100, and its deviation ΔI is amplified by the proportional-integral amplifier 108 of the control means. It An output voltage reference value V * is obtained by adding the output of the proportional-plus-integral amplifier 108 and the sine wave signal Vs, and the switching element of the power conversion circuit 100 is controlled via the PWM controller 109 according to the output voltage reference value V *. To be done. Thereby, the power conversion circuit 100 is operated so that the output current Is becomes the power command value corresponding to the current amplitude reference value Im *. in this case,
The output current Is is a sine wave current having the same phase as that of the AC power system 103, and operation with a power factor of 1 is possible.

The DC power supply required for the above control operation of the control means is generated from the AC output of the power conversion circuit 100 by the power supply circuit and supplied to the control means and the PWM controller 109. A capacitor input type circuit configuration is often used as a power supply circuit to drive the PWM controller 109 by rectifying the AC power obtained from the receiving point, smoothing it with an electrolytic capacitor, and stepping it down with a step-down circuit. ± 15
Create the + 5V power supply required for the V power supply and control means,
It is supplied to the control means and the PWM controller 109.

In order to make the output current of the power conversion circuit 100 a sine wave current having a waveform with the same phase as the AC power system 103, a normalized sine wave signal having no phase with respect to the detected system voltage is generated. There is also a grid-connected inverter device to which a sine wave output device as shown in FIG. 14 is applied. This sine wave output device inputs a system voltage (1 in FIG. 15), compares it with a reference voltage of 0 V, outputs a polarity of the input AC voltage, and a constant frequency serving as a reference for time measurement. The oscillator 201 for outputting the clock signal (3 in FIG. 15) is provided. The voltage comparator 200 outputs H when the input AC voltage is higher than 0 V, and outputs L when the input AC voltage is low, so that the output waveform is as shown by 2 in FIG. The output of the voltage comparator 200 and the clock signal from the oscillator 201 are input to the rising edge detector 202.

The rising edge detector 202 is a voltage comparator 200.
At the rise of the output of, the pulse as shown by 4 in FIG. 15 is generated. Output of rising edge detector 202 and oscillator 201
Clock signal is input to the current time counter 203,
The present time counter 203 is cleared to 0 by the pulse of the rise detector 202 and increments its value by the clock signal of the oscillator 201, so that its output waveform is as shown by 5 in FIG. The maximum value of the output of the present time counter 203 (the maximum value immediately before being cleared to 0) is held in the period register 204 by the pulse of the rising edge detector 202 (6 in FIG. 15). The output of the current time counter 203 is divided by the output of the period register 204 by the divider 205 to obtain the current phase with respect to the period of the input signal (7 in FIG. 15).
Is output to the signature table 206. The sine table 206 is a rook-up table that inputs a phase signal and outputs a sine calculation value.
The sine wave shown in 8 of 5 is output.

As a result, a sine wave synchronized with the system voltage can be obtained. The oscillator 201 is shown in FIG.
, The obtained sine wave also has low resolution in the time-axis direction, but in reality, the output of the oscillator 201 is set to a sufficiently high frequency so that a sine wave with little distortion is obtained. It is what is done.

[0009]

In the conventional grid-connected inverter device as described above, the output voltage reference value V * of the power conversion circuit 100 is changed to the current amplitude reference value Im * as described above.
And the deviation ΔI (I * -Is) between the current reference value I * and the detected current value Is obtained by the product of the sine wave signal Vs detected from the AC power system 103 are proportionally and integral amplified and detected from the AC power system 103. It is obtained by adding the actual system voltage Vs.

However, there is a calculation delay time in the control means between the detection of the phase of the AC power system 103 from the system voltage and the output of the power conversion circuit 100 by the output voltage reference value V *, and the Conversion means 100
When the voltage is output, the phase of the actual system voltage has already advanced by the operation delay time. In such a case, it becomes difficult to supply a neat and clean current to the AC power system 103.

That is, when the output voltage reference value V * is represented by the current reference value I *, the current detection value Is and the system voltage Vs, V * = Vs + PI (I * -Is). Where P
I is a proportional integral constant. Normally, the sampling frequency of the control means is set to the frequency of the system voltage (50Hz, 60H
z) is controlled as a sufficiently high frequency (for example, 20 kHz). When the system voltage is increasing, as shown in an enlarged view in FIG. 16, the time t1 in the sampling time is increased.
In order to flow the current value it1 * (A) into the AC power system 103 at the time, the current detection values it0 and i detected at the time t0
When the product of the deviation ΔI (ΔI = it1 * -it0) of t1 * and the proportional integral constant PI is time t1, the AC power system 10
In order to pass it1 * (A) to 3, the output voltage reference value V * is raised from the system voltage Vs.

However, although it is actually intended to flow it1 * (A), at time t1, the actual system voltage Vs is larger than at time t1, so the output voltage of the power conversion circuit 100 is insufficient with respect to the line impedance. And it1 *
(A) It cannot be flushed. Therefore, the actual output current Is of the power conversion circuit 100 is the ideal current command value I *.
The deviation ΔI (it2 * -it) from the current command value I * (t2) is to be reduced at the time t2, which is smaller than (t1).
1) will increase.

Further, when the system voltage is decreasing, as shown in an enlarged view in FIG.
In order to flow the current value it1 * (A) in the AC power system 103 when the value is 1, the product of the deviation ΔI (it1 * -it0) between the detected current value it0 and it1 * detected at the time t0 and the proportional integral constant PI ( ΔI <0) while the system voltage is decreasing, but at time t
When it is 1, the output voltage reference value V * is lowered from the system voltage Vs in order to flow it1 * (A) to the AC power system 103.

However, in this case as well, it1 * is actually
(A) Although it is intended to flow, at time t1, the actual system voltage Vs is smaller than at time t1, and therefore the potential difference between the output voltage of the power conversion circuit 100 and the system voltage increases, so the AC power system 103 A large amount of current flows, the actual output current Is of the power conversion circuit 100 increases more than the ideal current command value I * (t1), and the current command value I * (t2) is supplied at the next time t2. Deviation of ΔI (it2 *-
It1) will increase.

As described above, the deviation Δ which is the control amount used for the control
As I increases, the calculation error increases. As a result, the harmonic component of the sine wave current flowing in the AC power system 103 increases, and a clean and tidy current is supplied to the AC power system 103.
Difficult to supply to.

Further, since the power receiving point of the power supply circuit for producing the power supply necessary for the operation of the control means is located on the side of the AC power system 103 behind the filter 101, the current ripple of the power supply circuit is the power ripple. There is also a problem that the harmonic components of the current waveform flowing in from the receiving point of are increased.

Further, in the conventional sine wave output device for generating a sine wave necessary for controlling the output of the power conversion circuit 100, when noise is present near the zero cross of the input system voltage (1 in FIG. 18), The contents of the period register 204 become smaller, the phase of the output of the divider 205 becomes larger as shown by 7 in FIG. 18, and the output of the sine table 206 becomes as shown in FIG.
A sine waveform with a high frequency is output as shown in 8 of 8. This waveform is an output that is completely different from the input voltage, and a signal that is inconvenient for proper control of the power conversion circuit 100 will be generated.

In order to improve the time-axis direction resolution with this sine wave output device, it is necessary to increase the frequency of the output of the oscillator 201. For example, if the time-axis direction resolution is 1 μsec, 5
To measure up to 20 msec of the power supply cycle of 0 Hz, the current time counter 203 and the cycle register 204 are at least 15B.
IT is required, and it is actually difficult to improve the time-axis direction resolution.

The present invention has been made in order to solve the above-mentioned conventional problems, and its object is to provide a grid interconnection inverter capable of supplying a current with a high waveform accuracy with few harmonic components to an AC power system. It is to obtain a device, and to obtain a waveform generator for improving waveform accuracy.

[0020]

In order to achieve the above object, a grid interconnection inverter device according to a first aspect of the present invention provides an output voltage command value for a power conversion means, a deviation between a current command value and an actual current value. Is obtained by adding the actual system voltage by proportional-integral amplification, and adding the correction amount for correcting the actual system voltage increase and decrease due to the control delay time to the system voltage to obtain the output voltage command value for the power conversion means. Is generated.

In order to achieve the above object, a system interconnection inverter device according to a second aspect of the present invention proportionally-integrates and amplifies a deviation between a current command value and an actual current value for an output voltage command value for the power conversion means, When adding the actual system voltage,
A normalized sine wave signal that is synchronized with the system voltage is generated from the phase and frequency of the system voltage of the AC power system, and a control delay is performed using a sine wave signal that is the phase of this sine wave signal made π / binary. The output voltage command value for the power conversion means is generated by adding a correction amount for correcting the actual rise / fall of the system voltage due to time.

In order to achieve the above object, the grid-connected inverter device according to claim 3 is connected to an AC power system,
Power conversion means for converting DC power into AC power and outputting the AC power,
A power supply circuit that generates electric power necessary for the control operation of the power conversion means, in a grid interconnection inverter device including control means for generating AC power synchronized with the grid frequency and grid voltage of the AC power grid. Is a capacitor input type circuit configuration, and the power receiving point of the power supply circuit is in the vicinity of a current detection unit for detecting the output current of the power conversion unit provided to obtain a current command value for the power conversion unit. Is.

In order to achieve the above object, the grid-connected inverter device according to claim 4 is connected to an AC power system,
A power conversion means for converting DC power into AC power and outputting it.
Control means provided with phase detection means for measuring a system frequency and a zero-cross point from the system voltage of the AC power system, and sine wave generation means for generating a sine wave normalized by the system phase obtained by the phase detection means. According to the present invention, a system interconnection inverter device configured to generate AC power synchronized with a system frequency and a system voltage of an AC power system, the phase detection means of which inputs the system voltage as an input signal and outputs this input signal. A / to convert to digital signal at regular time intervals
A D converter, a data buffer that stores the digital signal output of this A / D converter for a certain period of time, and updates the stored contents of the stored digital signal at each sampling cycle, and a digital buffer in this data buffer. A signal is input and the average value detector that extracts these average values and each of the digital signal data in the data buffer is multiplied by the time from the hypothetical origin, and the addition result is the square of the time from the hypothetical origin. It is provided with a slope detector for detecting a slope by dividing by a sum, a data buffer output, and a zero-cross detector for inputting a signal of an average value detector to obtain a zero-cross point of the input signal.

In order to achieve the above-mentioned object, a grid interconnection inverter device according to a fifth aspect of the present invention is such that the zero-cross detector in the means according to the fourth aspect is activated by the output of the zero-cross detector, and an average value detector and a slope are obtained. An intersection detector that measures the time to the zero crossing of the input signal by the signal of the detector, a current time register that is initialized by the output of this intersection detector and adds the processing cycle for each processing cycle, and the intersection detector An output, a period register that calculates and holds the period of the input signal from the contents of the current time register, and a divider that divides the output of the current time register by the output of the period register to detect the current phase of the input signal. It is connected.

In order to achieve the above object, the grid interconnection inverter device according to a sixth aspect of the present invention inputs the present phase of the input signal, which is the output of the divider, to the divider in the means according to the fifth aspect. , A sine table for reading out sine data corresponding to the phase.

In order to achieve the above object, a waveform generator according to a seventh aspect of the present invention is a phase detecting means for measuring a frequency and a zero cross point from a voltage of an AC system, and a phase obtained by the phase detecting means is normalized. And a sine wave generating means for generating a sine wave, by inputting the voltage as an input signal,
An A / D converter that converts this input signal into a digital signal at fixed time intervals, and the output of the digital signal of this A / D converter is stored for a certain period of time, and the stored digital signal is sampled at each sampling cycle. A data buffer for updating the stored content, an average value detector for inputting the digital signal in the data buffer and extracting the average value of these,
A slope detector that detects the slope by multiplying the time from the hypothetical origin for each of the digital signal data in the data buffer and dividing the added result by the sum of squares of the time from the hypothetical origin, and the data buffer. The output of, and the signal of the average value detector is input, a zero-cross detector that obtains the zero-cross point of the input signal, and the output of this zero-cross detector is activated, and the average value detector and the inclination detector An intersection detector that measures the time until the zero crossing of the input signal by a signal, a current time register that is initialized by the output of this intersection detector, and adds the processing cycle for each processing cycle, and the output of the intersection detector The cycle register that calculates and holds the cycle of the input signal from the contents of the current time register, and the output of the current time register. A table that inputs the current phase of the input signal that is the output of the divider and the divider that detects the current phase of the input signal by dividing by the output of the period register and reads the waveform data corresponding to that phase. It is composed of and.

[0027]

Embodiments of the present invention will now be described with reference to the drawings. First Embodiment of the Invention FIG. 1 is a configuration diagram showing a grid-connected photovoltaic power generation system to which the grid-connected inverter device according to the first embodiment is applied. In this grid-connected solar power generation system, the solar cell 1 is connected to a grid-connected inverter device, and the grid-connected inverter device outputs DC power generated by the solar cell 1 by PWM control (pulse width modulation control). It is configured to be converted to AC power of 50 Hz / 60 Hz and supplied to the commercial AC power system 2.

The system interconnection inverter device is mainly composed of a power conversion circuit 3, a control circuit 4, and an interconnection switch 5. The power conversion circuit 3 is composed of four switching transistors Q1 to Q4 as an IGBT bridge, flywheel diodes are connected in reverse polarity to the respective switching transistors Q1 to Q4, and the respective switching transistors Q1 to Q4 are gate driven. By the PWM controller 6 which generates a signal, the switching transistors Q1, Q4, Q3 and Q2 for one phase are simultaneously turned on.
It is driven ON / OFF alternately so that it does not occur N times. A diode 7 for backflow prevention, an input side noise filter 8, an input capacitor 9, a step-up chopper circuit 10, and an input capacitor 11 are sequentially connected to the input side of the power conversion circuit 3 from the solar cell 1 side. The output side of the power conversion circuit 3 is connected to the commercial AC power system 2 via a choke coil 12 as an output filter, a smoothing capacitor 13, an output side noise filter 14, and an interconnection switch 5.

The diode 7 for preventing backflow is the solar cell 1
Input side noise filter 8
Prevents the noise generated inside the power conversion circuit 3 from flowing out. The input capacitor 9 serves to reduce the ripple of the direct current flowing from the solar cell 1. The step-up chopper circuit 10 boosts the voltage of the solar cell 1 so as to be connected to the commercial AC power system 2, and the IGBT 15
The chopping width is controlled so that the voltage becomes a predetermined voltage. The output of the power conversion circuit 3 turns on the DC voltage of the input capacitor 11 by the switching transistors Q1 to Q4.
Since it is turned off, it becomes a rectangular wave. This rectangular wave is converted into a sine wave by the output filter including the choke coil 12 and the smoothing capacitor 13, and is supplied to the commercial AC power system 2 via the interconnection switch 5 and the commercial transformer 16.

The control circuit 4 is a switching transistor Q which constitutes the power conversion circuit 3 by the PWM controller 6.
1 to Q4 are driven to cause the power conversion circuit 3 to output a current synchronized with the phase of the system voltage to the commercial AC power system 2. The system voltage Vs of the commercial AC power system 2 is taken into the control circuit 4 by a transformer or the like, and the system frequency and the zero-cross point of the commercial AC power system 2 are measured by the phase detection circuit 17,
The phase of the commercial AC power system 2 is detected and input to the sine wave generation circuit 18. The sine wave generation circuit 18 is also an arithmetic circuit that obtains an instantaneous value of a sine wave, and thereby a normalized instantaneous value (S2) of a sine wave is obtained.

The output voltage (S3) and output current (S4) of the solar cell 1 are also taken into the control circuit 4, and the output power of the solar cell 1 is calculated by the current command calculation circuit 19. The current command calculation circuit 19 determines the effective value of the current that can be output while comparing it with the previous output power, and the current command value (S
5) is output. The control circuit 4 uses the output of the current command calculation circuit 19 and the output of the sine wave generation circuit 18 to perform the well-known maximum power point tracking control.

That is, the instantaneous value (S2) of the sine wave (sin ωt.ω is an angular frequency) normalized with the current command value (S5).
Is multiplied by the multiplier 20 to obtain the command value I * (S6) (√2I · sinωt) of the current to be output at the time t. This current command value I * (S6) and the current value I of the actual output of the power conversion circuit 3 detected by the current transformer 21
The difference S8 (I * -Is) from s (S7) is amplified by the proportional-plus-integral amplifier 22, and the instantaneous value Vs (S1) of the system voltage.
And the correction amount Δ of the system voltage calculated by the correction means 23.
System voltage command value Vs * (S1
0) is added to the output of the proportional-plus-integral amplifier 22, and the command value V * (S9) of the output voltage of the power conversion circuit 3 is obtained.
The PWM controller 6 outputs a gate drive signal to the switching transistors Q1 to Q4 according to the voltage command value V * (S9).

Instantaneously, the instantaneous value Is (S7) of the actual current detected by the current transformer 21 becomes the current command value I * (S
When it is smaller than 6), the output voltage V * (S9) of the power conversion circuit 3 is made higher than the system voltage Vs (S1), and a current is supplied to the commercial AC power system 2 via the line impedance. The instantaneous value Is (S7) of the actual current is the current command value I * (S
6) If it becomes larger than the output voltage V * of the power conversion circuit 3,
(S9) is lowered so that no current flows in the commercial AC power system 2. That is, by controlling so that the instantaneous value Is (S7) of the actual current becomes equal to the current command value I * (S6), a 50 Hz / 60 Hz sine wave current is supplied to the commercial AC power system 2. This is determined in the control circuit 4 of FIG. 1, and the voltage is raised or lowered by the IGBT bridge of the switching transistors Q1 to Q4 according to the voltage command of V * (S9).

The correction means 23 for generating the correction amount ΔV (S12) uses the commercial AC power system 2 from the system voltage Vs (S1).
Of the system voltage Vs (S1) that has changed from the time when the phase is detected to the time when the power conversion circuit 3 outputs the voltage obtained as the output voltage reference.
Is output. That is, the correction means 23 is a phase advance means 24 for advancing the phase of the normalized sine wave signal (S2) having the same phase as the system voltage Vs obtained by detecting the phase and the cycle from the system voltage Vs by π / 2. , Sampling time output means 25 for outputting sampling time T for obtaining control information
And the integrated output of the sampling time output means 25 is output to the output of the phase advance means 24.

The instantaneous value Vs (t) of the actual voltage of the commercial AC power system 2 is Vs = Vmsi when the peak value is Vm.
It can be represented by nωt. Sampling time T
The voltage Vs (t + T) delayed by (second) is Vmsin (ωt
+ T ') can be represented. Here, T ′ is ωT. The voltage difference ΔV during this T (second) is ΔV = Vs (t
+ T) −Vs (t) = Vmsin (ωt + T ′) − Vm
sin ωt = Vm (sin (ωt + T ′) − sin ω
t) = Vm (2cos ((ωt + T ′ + ωt) / 2) s
in ((ωt + T′−ωt / 2)) = Vm (2cos
(Ωt + T ′ / 2) sin (T ′ / 2).

Here, normally, the control sampling time T
Is very short, for example, 50 microseconds when the sampling frequency is 20 kHz. Therefore, if T ′ = 0 in the above equation, ωt + T ′ / 2 → ωt
It is possible to set n (T ′ / 2) → T ′ / 2, and in the end, the potential difference ΔV can be expressed as Vmcosωt · T.
Since the normalized sine wave signal (S2) having the same phase as the system voltage detected from the system voltage is obtained, the potential difference ΔV is calculated using this signal. That is, ΔV = Vmcos
In the formula of ωt · T, cos ωt = sin (ωt + π
/ 2), the phase of the sine wave signal (S2) is π / 2.
The advanced signal (S11) is generated and multiplied by the peak value 26 of the system voltage and the sampling time T to obtain the potential difference ΔV (S12) to be corrected. The corrected command value Vs * (S10) of the system voltage is the instantaneous value V of the system voltage.
It can be obtained by adding the above correction amount (potential difference ΔV) to s (S1).

The effect obtained by adding the correction amount ΔV to the instantaneous value Vs (S1) of the system voltage in this way is as follows. In FIG. 2 showing an enlarged view of the system voltage rising,
In order to flow the current value it1 * (A) to the commercial AC power system 2 at the time t1 in the sampling time T, the time t0
Deviation of current detection value it0 and it1 * detected at
The product of (ΔI = it1 * -it0) and the proportional integral constant PI is it1 * in the commercial AC power system 2 at time t1.
(A) The output voltage of the power conversion circuit 3 is increased from the system voltage Vs in order to flow. At time t0, the current command calculation circuit 19 in FIG. 1 issues a command to flow it1 * (A) at time t1.

Since the actual system voltage Vs is large at time t1, the amount of increase in system voltage (correction amount ΔV) is added in advance at time t0, so that the power conversion circuit is added to the line impedance. 3 output voltage V *
Is a voltage that allows a current value it1 * (A) to flow in the commercial AC power system 2. That is, it is possible to approach the ideal current command value I * (t1), and the deviation ΔI (it from the current command value I * (t2) to flow at the next time t2.
2 * -it1) can be significantly reduced as compared with the case where the correction amount ΔV is not added.

Further, when the system voltage is decreasing, as shown in an enlarged view in FIG.
In order to flow the current value it1 * (A) into the commercial AC power system 2 when 1, the product of the deviation ΔI (it1 * -it0) between the current detection values it0 and it1 * detected at time t0 and the proportional integral constant PI. (While the system voltage is decreasing, ΔI <0), the time t
In the case of 1, the output voltage is lowered in order to flow it1 * (A) to the commercial AC power system 2.

Since the system voltage Vs becomes small at time t1, the amount by which the system voltage drops at time t0 (ΔV <0) is added in advance, so the potential difference between the output voltage of the power conversion circuit 3 and the system voltage is added. Is the current It1 *
(A) Since the current can flow, the actual output current Is of the power conversion circuit 3 approaches the ideal current command value I * (t1). The current command value I * to flow at the next time t2
Deviation ΔI (it2 * -it1) from (t2) is the correction amount Δ
It can be reduced compared to when V is not added.

As described above, by reducing the deviation amount to be controlled, the calculation error is reduced, and as a result, the harmonic component of the sine wave current flowing in the commercial AC power system 2 is reduced, and the waveform accuracy is high. The current waveform can be supplied to the commercial AC power system 2.

The cosine wave signal used when calculating the correction amount ΔV is a signal obtained by advancing the phase of the normalized sine wave signal having the same phase as the system voltage detected from the system voltage by π / 2. By using it, it is not necessary to store the data of the cosine wave signal in the memory, so that the memory area spent for the correction can be saved. Whether the system voltage is rising or falling can be monitored by the phase detection circuit 17 of FIG. 1 by the phase detection circuit 17 and therefore, whether the system voltage is rising or falling can be known by a flag or the like in the software.

Since the correction amount ΔV is determined by the control sampling time T and the peak value 26 of the system voltage, the correction amount ΔV for the phase of one cycle of the commercial AC power system 2 is stored in the memory in advance. The correction amount ΔV can be added to the actual system voltage to obtain the output voltage command value V * of the power conversion circuit 3.

As shown in FIG. 4, the correction amount ΔV in one cycle of the commercial AC power system 2 has the largest zero-cross points at the phases 0 ° and 180 °, and the peak values at the phases 90 ° and 270 °. The point is the smallest, and the value of the correction amount ΔV is
The phase gradually decreases from 0 degrees to 90 degrees, and from 90 degrees to 180 degrees
Since the phase is large up to 180 degrees, the phase gradually decreases from 180 degrees to 270 degrees, and increases from 270 degrees to 360 degrees, the correction amount data only needs to be 1/4 cycle. Lever data may be used.

For example, as shown in FIG. 4, the correction data when the phase is 0 degrees is D0, the correction data one sampling time before the phase is 90 degrees is Dn, and the correction data when the phase is 90 degrees is Dn. Correction data D (n-1) for one sampling time before the phase is 90 degrees, and correction data D0-D (from 0 degrees to one sampling time before the phase 90 degrees are used every time the phase advances. n-1) is used in reverse.
Further, when the phase is 180 degrees to 270 degrees before one sampling time, the correction amount gradually decreases, so that the correction data is used in the order of D0 to D (n-1). Then, since the correction amount increases until one sampling time before the phase is 270 degrees to 360 degrees, the correction data is used in the order of D (n-1) to D0. By doing so, the correction can be performed with the number of quarters of the correction data for one cycle of the commercial AC power system 2.

This inverter is based on a current command to flow a current of just A. The commanded current is larger or smaller than the current Is (S7) actually flowing in the commercial AC power system 2. Or see the deviation (Δ
I), it operates, but since it outputs as a voltage as the output of the inverter, in the end, how much the voltage can be raised or lowered compared to the actual system voltage of the commercial AC power system 2 to flow the commanded current? Therefore, PI (I
* -Is) is exactly how much this voltage is raised or lowered, Vs is just the system voltage, and adding ΔV is raising the accuracy of Vs.

Second Embodiment of the Invention The grid-connected inverter device according to the second embodiment is characterized by a power supply circuit that generates and supplies a power supply necessary for controlling the power conversion circuit 3 as shown in FIG. 5, except for the configuration related to the power supply circuit. Is the same as the grid-connected inverter device described in the first embodiment. Therefore, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The DC power supply required for the operation of the control circuit 4 is generated from the AC output of the power conversion circuit 3 by the power supply circuit 27 and supplied to the control circuit 4. This power supply circuit 27 has a capacitor input type circuit configuration, and rectifies the AC power obtained from the receiving point 28, smoothes it with an electrolytic capacitor, steps down with a step-down circuit, and drives the PWM controller 6 by ± 15V. The power supply of +5 V required for the control circuit 4 and the control circuit 4 is generated and supplied to the control circuit 4 and the PWM controller 6. In the grid-connected inverter device according to the second embodiment,
The power receiving point 28 of the power supply circuit 27 is provided in the vicinity of the current detecting current transformer 21 connected to the output side of the power conversion circuit 3 and before the choke coil 12.

A current ripple is generated in the capacitor input type power supply circuit 27. When this current ripple flows into the commercial AC power system 2 from the power receiving point 28 of the power supply circuit 27, the harmonic component of the current waveform increases as shown in 1 of FIG.
It is possible to prevent the harmonic component of the current waveform from increasing by making the receiving point 28 of No. 7 near the current detecting current transformer 21 connected to the output side of the power conversion circuit 3.

As described in the first embodiment, the control circuit 4 controls the output of the current command calculation circuit 19 and the sine wave generation circuit 18.
Maximum power point tracking control is performed by the output of. Actually, the difference S8 (I * -Is) between the current command value I * (S6) and the current value Is (S7) of the actual output of the power conversion circuit 3 detected by the current transformer 21 is the proportional-integral amplifier. 22 and the instantaneous value Vs (S1) of the system voltage and the correction amount ΔV (S12) of the system voltage calculated by the correction means 23.
The system voltage command value Vs * (S10) obtained by adding the minutes is added to the output of the proportional-plus-integral amplifier 22 to obtain the command value V * (S9) of the output voltage of the power conversion circuit 3, and this voltage command value V * According to (S9), the PWM controller 6 outputs a gate drive signal to the switching transistors Q1 to Q4.

Therefore, the current including the current ripple of the power supply circuit 27 flowing from the receiving point 28 of the power supply circuit 27 is output by the current transformer 21 to the current value Is of the output of the power conversion circuit 3.
The current value Is is detected as (S7).
(S7) and current command value I * (S6) difference S8 (I *
-Is) is amplified by the proportional-plus-integral amplifier 22, and PWM
The gate drive signal of the controller 6 will be generated. That is, the voltage command value V * (S9) is determined in consideration of the amount of current ripple generated by the power supply circuit 27, and the power conversion circuit 3 is controlled by this, so that the waveform accuracy shown in 2 of FIG. A high current waveform will be output to the commercial AC power system 2. Other functions are the same as those of the first embodiment.
Is the same as

Third Embodiment of the Invention The feature of the grid-connected inverter device according to the third embodiment is that the phase detection circuit 17 and the sine wave generation circuit 18 in the grid-connected inverter device shown in FIG. The configuration is the same as that of the grid interconnection inverter device described in the first embodiment. Therefore, FIG. 1 uses this as it is, and the same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. FIG. 7 shows a signal processing block diagram, in which the voltage instantaneous value data is input by each component, the zero cross is obtained, the current time from the zero cross as a starting point is calculated, and sine wave data, that is, a reference signal is generated.

The grid-connected inverter device according to the third embodiment obtains a normalized sine wave necessary for causing the power conversion circuit 3 to output a current synchronized with the phase of the grid voltage to the commercial AC power system 2. The phase detection circuit 17 and the sine wave generation circuit 18 are configured as shown in FIG. That is,
As shown in FIG. 7, the sine wave output circuit including the phase detection circuit 17 and the sine wave generation circuit 18 has an A / D converter 29,
Data buffer 30, average value detector 31, inclination detector 3
2, a zero cross detector 33, an intersection detector 34, a current time register 35, a cycle register 36, a divider 37, and a sine table 38. FIG. 8 shows operation waveforms of the respective parts of FIG.

The A / D converter 29 inputs a system voltage as shown in FIG. 8 as an input signal and converts this input signal into a digital signal at a constant time interval h. Data buffer 30
Stores the output of the digital signal of the A / D converter 29 for a certain period of time, updates the stored content of the stored digital signal at each sampling cycle, and stores the latest n data in the register Z (-n + 1). , Z (−n + 2) ... Z (0). The average value detector 31 inputs the data in the data buffer 30 and extracts these average values. The inclination detector 32 includes an average value detector 31 and a data buffer 30.
The slope is detected by multiplying the time from the hypothetical origin with respect to each of the data in, and dividing the added result by the sum of squares of the time from the hypothetical origin. Zero cross detector 33
Inputs the output of the data buffer 30 and the signal of the average value detector 31 to obtain the zero-cross point of the input signal.

The intersection detector 34 is the zero-cross detector 33.
Is started by the output of the above, and the time until the zero cross of the input signal is measured by the signals of the average value detector 31 and the inclination detector 32. The current time register 35 is initialized by the output of the intersection detector 34, and adds the processing cycle for each processing cycle. The cycle register 36 calculates and holds the cycle of the input signal from the output of the intersection detector 34 and the contents of the current time register 35. The divider 37 divides the output of the current time register 35 by the output of the period register 36 to detect the current phase of the input signal. The sine table 38 inputs the current phase of the input signal which is the output of the divider 37, reads the sine data corresponding to the phase from the table, and outputs a normalized sine wave (S2).

FIG. 9 is a flow chart of the operation of FIG. 7, and the operation waveform of each part is shown in FIG. As shown in the flow chart of FIG. 9, the interrupt processing performed by the control circuit 4 at regular time intervals h causes the current time register 35
Interrupt interval h is added to the content C of (# 1 in FIG. 9),
The data in the data buffer 30 is shifted, and the data buffer 30 holds the latest n pieces of data (# 2 in FIG. 9). Here, the register Z (-i) holds the A / D conversion value of the A / D converter 29 that is h · i before the present time. Since the latest data is input to the register Z (0), register Z (−n + 1) = register Z (−n
+2), register Z (-n + 2) = register Z (-n +)
3) ... Shift data with register Z (-n) = Z (0). Then, the input signal which is the system voltage is A / D converted and saved in the register Z (0) (# 3 in FIG. 9). As a result, the data buffer 30 holds the latest n pieces of data up to the present.

Next, in # 4 of FIG. 9, the average value detector 3
The average value a0 of the contents of the data buffer 30 is obtained by 1, and the inclination a1 of the data string is obtained by the inclination detector 32 in # 5 of FIG. 9 (see FIG. 10). Slope a1
Is obtained by multiplying the time from the hypothetical origin (divided by the processing time interval h) for each of the data in the data buffer 30 and dividing the sum by the sum of squares of the time from the hypothetical origin. Is the slope of the regression line B obtained by the method of least squares for the data in the data buffer 30.

The average value detector 3 in # 6 and # 7 of FIG.
The zero cross is detected by the output of 1 and the output of the data buffer 30. In # 6 and # 7 of FIG. 9, j
Be an arbitrary integer from 0 to n−1, and a00, a
If 01, a02, and a03 are predetermined appropriate integers, and the polarity flag is a flag that holds 1 when the polarity of the input signal is positive and holds 0 when the polarity of the input signal is negative, the polarity flag is 0 and the average value a
0 is between a00 and a01, and Z of the data buffer 30
When -j becomes positive (YES in # 6 of FIG. 9),
10, the time tk from the point where the voltage waveform of the input signal crossed zero to the present is tk as shown in FIG.
= {1/2 (n-1) + a0 / a1} · h, the time T at the current zero cross starting from the previous zero cross is found at # 9 in FIG. 9, and the cycle register 36 is updated. It Here, the time T is C since the previous zero cross is the starting point, so T = C
-Tk is required.

Since the time from the current zero cross to the present is tk, the content C of the present time register 35 is shown in FIG.
In # 10, C = tk is replaced with a time starting from a new zero cross. Then, in this case, assuming that the zero cross is recognized, the polarity flag is set to 1 in # 11 of FIG. 9, and the current time C is divided by the periodic data T to obtain the phase P by the divider 37 in # 14 of FIG. This phase P
Is input to the sine table 38, the sine value S corresponding to the phase is read from the table in # 14 of FIG. 9, and the normalized sine wave is output. This sine wave has the same phase as the system voltage of the input signal and has little distortion.

If NO in # 6 of FIG. 9, the polarity flag is 1 in # 7 of FIG. 9, the average value a0 is between a02 and a03, and Zj of the data buffer 30 becomes negative. 9 (YES in # 7 of FIG. 9), the polarity flag of the input signal is changed to negative in # 12 of FIG. 9, the polarity flag is set to 0, and the processes of # 13 to # 14 of FIG. 9 are performed. Otherwise (NO in # 7 of FIG. 9), it is assumed that the polarity of the input signal has not changed, and the processes of # 13 to # 14 in FIG. 9 are performed as they are.

When noise is added to the system voltage which is the input signal, as shown in FIG. 11, the intersection point which is the output of the current time in the third embodiment with respect to the time uk from the actual zero cross point to the present time. The output of the detector 34 becomes tk, and the deviation with respect to the time uk can be suppressed to be small. In addition,
The vk shown in FIG. 11 is the time output of the current time in the sine wave output device described in the section of the related art, and the actual time uk
The deviation from The other functions are the same as those of the system interconnection inverter device shown in the first embodiment.

The detection of the inclination by the inclination detector 32 described above is performed by obtaining the coefficient of the regression line B obtained by the least square method by a statistical method. That is, the data in FIG. 12 is a set of data (k-i, xk-
i), i = 0, 1 ... N−1, where the horizontal axis represents N sets of points with the interval 1 and the regression line B is X = a0 + a1.
When I is set, a0 and a1 are calculated by the following equations.

[0063]

[Equation 1]

[Equation 2]

[Mathematical formula-see original document]

(Equation 3) Is N · k−1 / 2 (N−1) · N, and if k is selected so that this is 0, that is, k = ½ (N−1), then a
0 and a1 are as shown in the following equation.

[0065]

(Equation 4)

(Equation 5)

The zero-cross point I0 where X = a0 + a1I intersects X = 0 is I0 = -a0 / a1. Since the sampling point at k on the rightmost side is at a position of 1/2 (N-1) from the hypothetical origin, the length on the I axis (time axis) from the zero cross point to k is 1/2 (N-). 1) + a0 / a1 and {1/2 (N-1) + a when the data interval is h
0 / a1} · h. As a result, the zero-cross position can be detected with a finer resolution than the constant A / D conversion time gap h (generally 50 μsec in digital control). When controlling the inverter with the system voltage as input,
No new device is required, and a program can be added to enable this zero-cross detection.

[0067]

As is apparent from the description of the embodiment, according to the inventions of claims 1 and 2, when the command value of the output voltage of the power conversion means is obtained, the actual AC power system is obtained. Since the output voltage command value for the power conversion means is generated by adding the correction amount for correcting the increase / decrease of the actual system voltage due to the control delay time that occurs from the detection of the system voltage of the above to the output of the power conversion means. The deviation between the command value of the current flowing in the AC power system and the actual current value can be reduced, the control amount can be reduced, and the calculation error can be reduced. Therefore, the harmonic component of the sinusoidal current flowing in the AC power system is reduced, a clean current with high waveform accuracy can be supplied to the AC power system, and good power quality can be secured.

According to the invention of claim 3, the current including the current ripple component generated by the power supply circuit is detected, and the voltage command in consideration of the current ripple component is issued by the control means. The current waveform supplied to the AC power system has high waveform accuracy, and good power quality can be secured.

According to the inventions of claim 4, claim 5, and claim 6, the zero-cross position can be detected with a resolution finer than the conversion time interval of the A / D converter.
Even when noise is added to the input signal to the converter, it is possible to make it difficult to reduce the detection accuracy of the zero cross. Therefore, the deviation between the command value of the current flowing in the AC power system and the actual current value can be reduced, and the error in calculation is also reduced, so the waveform accuracy of the sine wave current flowing in the AC power system is high, and good power quality is obtained. Can be secured.

According to the invention of claim 7, the zero-cross position can be detected with a resolution finer than the conversion time interval of the A / D converter, and a waveform generator with good waveform accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a grid interconnection inverter device according to first and third embodiments of the present invention.

FIG. 2 is an explanatory diagram showing the operation of the first embodiment of the present invention in an enlarged manner while the system voltage is increasing.

FIG. 3 is an explanatory diagram showing the operation of the first embodiment of the present invention in an enlarged manner while the system voltage is decreasing.

FIG. 4 is an operation explanatory diagram of the first embodiment of the invention.

FIG. 5 is a block configuration diagram of a grid interconnection inverter device according to a second embodiment of the invention.

FIG. 6 is an operation explanatory diagram of the second embodiment of the invention.

FIG. 7 is a signal processing block diagram of a sine wave output circuit in a grid interconnection inverter according to a third embodiment of the invention.

FIG. 8 is a signal waveform diagram of each part of FIG.

FIG. 9 is a flowchart regarding a sine wave output according to the third embodiment of the invention.

10 is an enlarged view of a zero cross portion of the input signal waveform of FIG.

11 is an explanatory diagram showing a state in which noise is added to the input signal waveform of FIG. 7.

FIG. 12 is an explanatory diagram related to calculation of zero-cross detection by the method of least squares in the grid interconnection inverter according to the third embodiment of the invention.

FIG. 13 is a block configuration diagram of a conventional grid interconnection inverter device.

FIG. 14 is a block diagram of a conventional sine wave output device.

15 is a signal waveform diagram of each part of the device of FIG.

FIG. 16 is an operation explanatory diagram of a conventional grid interconnection inverter.

FIG. 17 is an operation explanatory diagram of a conventional grid interconnection inverter.

FIG. 18 is a signal waveform diagram of each part shown in a state where noise is added to an input signal of the device of FIG.

[Explanation of symbols]

 1 Solar Battery 2 Commercial AC Power System 3 Power Conversion Circuit 4 Control Circuit 6 PWM Controller 17 Phase Detection Circuit 18 Sine Wave Generation Circuit 19 Current Command Calculation Circuit 21 Current Transformer 22 Proportional Integral Amplifier 23 Correcting Means 24 Phase Advance Means 25 Sampling Time output means 27 Power supply circuit 28 Receiving point 29 A / D converter 30 Data buffer 31 Average value detector 32 Slope detector 33 Zero cross detector 34 Intersection detector 35 Current time register 36 Period register 37 Divider 38 Sign table

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location H02N 6/00 H02N 6/00 H02P 7/63 302 H02P 7/63 302R 302L (72) Inventor Saka Kazunori Hirobe 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd.

Claims (7)

[Claims] 1. A power conversion unit that is connected to an AC power system and that converts DC power into AC power and outputs the AC power, and causes the power conversion unit to generate AC power synchronized with the system frequency and the system voltage of the AC power system. A system interconnection inverter device including a control means, wherein the control means compensates for a control delay that occurs from the detection of the actual system voltage of the AC power system to the output of the power conversion means. When the voltage is output to the power conversion means, a normalized sine wave signal synchronized with the system voltage is generated from the phase and frequency of the system voltage of the AC power system obtained by the phase detection means, and this sine wave is generated. The output voltage command value for the power conversion means is generated by adding the correction amount for correcting the actual rise / fall of the system voltage due to the control delay time by the correction means using the wave signal. And a grid-connected inverter device. 2. A power conversion means that is connected to an AC power system and converts DC power into AC power and outputs the AC power, and causes the power conversion means to generate AC power synchronized with the system frequency and the system voltage of the AC power system. A system interconnection inverter device including a control means, wherein the control means compensates for a control delay that occurs from the detection of the actual system voltage of the AC power system to the output of the power conversion means. When the voltage is output to the power conversion means, a normalized sine wave signal synchronized with the system voltage is generated from the phase and frequency of the system voltage of the AC power system obtained by the phase detection means, and this sine wave is generated. An output voltage command to the power conversion means by using a sine wave signal obtained by advancing the phase of the signal by π / 2 and adding a correction amount for correcting the actual rise / fall of the system voltage due to the control delay time. System interconnection inverter device and generates a. 3. A power conversion means connected to an AC power system for converting DC power into AC power and outputting the AC power, and AC power synchronized with the system frequency and the system voltage of the AC power system in the power conversion means. A grid interconnection inverter device including a control means, wherein a power supply circuit for generating the electric power necessary for the operation of the control means has a capacitor input type circuit configuration, and the power receiving point of the power supply circuit is the power A grid interconnection inverter device, characterized in that it is provided in the vicinity of a current detection unit for detecting an output current of the power conversion unit provided to obtain a current command value for the conversion unit. 4. A power conversion means connected to an AC power system for converting DC power into AC power and outputting the power, and phase detecting means for measuring a system frequency and a zero-cross point from a system voltage of the AC power system, and a phase detecting means. By the control means having a sine wave generation means for generating a sine wave normalized by the system phase obtained by the detection means, to generate AC power in synchronization with the system frequency and the system voltage of the AC power system. And an A / D converter for inputting the system voltage as an input signal to the phase detecting means and converting the input signal into a digital signal at constant time intervals, and the A / D converter. A data buffer for storing the output of the digital signal of the converter for a certain period of time, and updating the stored content of the stored digital signal at each sampling cycle; The digital signal in the data buffer is input, the average value detector that extracts these average values, and the data from the digital signal in the above data buffer is multiplied by the time from the hypothetical origin, and the result of addition is assumed above. A slope detector that detects the slope by dividing it by the sum of squares of the time from the origin, a zero cross detector that inputs the output of the data buffer and the signal of the average value detector to obtain the zero cross point of the input signal. And a grid interconnection inverter device. 5. The grid-connected inverter device according to claim 4, which is activated by an output of a zero-cross detector,
An intersection detector that measures the time to the zero cross of the input signal by the signal of the average value detector and the inclination detector, and a current time register that is initialized by the output of this intersection detector and adds the processing cycle for each processing cycle. An output of the intersection detector, a cycle register for calculating and holding the cycle of the input signal from the contents of the current time register, and an output of the current time register divided by the output of the cycle register for input signal And a divider that detects the current phase of the inverter. 6. The system interconnection inverter device according to claim 5, wherein a sine table for inputting the current phase of the input signal that is the output of the divider and reading sine data corresponding to the phase. A system interconnection inverter device characterized by being provided with. 7. A phase detecting means for measuring a frequency and a zero-cross point from a voltage of an AC system, and a sine wave generating means for generating a sine wave normalized by the phase obtained by the phase detecting means, Is inputted as an input signal, the input signal is converted into a digital signal at a constant time interval, and the output of the digital signal of the A / D converter is stored and stored for a certain period of time. A data buffer that updates the stored contents of a digital signal at each sampling cycle, an average value detector that inputs the digital signal in this data buffer and extracts the average value of these, and the data by the digital signal in the data buffer , The slope is detected by multiplying the time from the hypothetical origin and dividing the added result by the sum of squares of the time from the hypothetical origin. Detector, the output of the data buffer, and the signal of the average value detector are input to obtain the zero-cross point of the input signal, and the output of this zero-cross detector activates the average value An intersection detector that measures the time to the zero cross of the input signal by the detector and the signal of the inclination detector, and a current time register that is initialized by the output of this intersection detector and adds the processing cycle for each processing cycle. An output of the intersection detector, a cycle register for calculating and holding the cycle of the input signal from the contents of the current time register, and an output of the current time register divided by the output of the cycle register for input signal Input the current phase of the input signal that is the output of the divider and the divider that detects the current phase of, and read the waveform data corresponding to that phase. A waveform generator characterized by comprising a table.