JPS58186378A - Power converter - Google Patents

Abstract

PURPOSE:To suppress the variation in the voltage in an interlock system with other power source by synthesizing a deviation signal between the output voltage of an inverter and the set value and the detected signal of reactive power, thereby controlling the output voltage of the inverter. CONSTITUTION:The output of a power converter 2 is interlocked through a transformer 3 and a switch 4 to an AC power source 5, an error signal between the voltage reference 21 and the output voltage 12 is inputted to a voltage controller 23, an error signal between the effective power reference 31 and an effective power detector 32 is applied through a PLL circuit 34 to the control circuit 23, thereby controlling the converter 2. The reactive power is detected by a detector 41, synthesized by the error signal between the reference 21 and the output voltage 12, and inputted to the controller 32. Accordingly, when the set of the power reference 31 is varied, the input of the controller 23 is immediately varied by the signal of the detector 41, thereby maintaining the interlocking voltage of the power source 5 to the prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a nine-power converter IIi device which has been improved to suppress voltage fluctuations at the interconnection point when operated in interconnection with other AC t & sources. It is related to.

(b) Description of the prior art For example, one of the purposes of interconnecting a power converter using an inverter and another AC power source is to stabilize the voltage at the interconnection point and supply stable power to the load. Become brown.

In order to stabilize the voltage at the grid connection point, conventionally, a grid connection round impedance (hereinafter referred to as grid connection impedance) is provided between the power converter and the AC power supply, and the voltage is applied to the grid connection impedance at the turtle and the ground. It is known to control the voltage generated by a power converter using a power converter. FIG. 1 shows a conventional example.

In the figure, l is the source of DC 1, and the DC output of DC power #1 is converted to AC by the power converter 12vC, and the transformer also serves as the interconnection impedance! A predetermined voltage converter I3 is connected to the AC area flA5 via a switch 4.

Depending on the control circuit 100, the voltage reference 21 and two of the transformers 3
The next voltage 12 is compared, and the deviation 211 is determined by the error amplifier 2.
The output signal 22m of the error amplifier 22 is input to the voltage control circuit 23.

Similarly, the output of the active power reference 31 and the active power detection circuit 32 are compared, and the deviation 33a is given to the input of the error amplifier 330, and the output of the error amplification 933 (D output is a phase locked loop (phase 1ocked 1oop)). The interwoven system voltage 13 of the AC power supply 5 is given to the other input port of the PLL circuit 34 as a phase reference.The PLL circuit 34 is a well-known circuit, but it can be easily explained.
dL clear.

The ig2 diagram is an example of a block diagram of PLL1 path 34,
The configuration of the Pi, L circuit 34 is based on the low frequency C of the phase error detector 4.
It consists of a wave @ LPF and a voltage controlled generator 11 @ VCO.

The device P publication is the phase 4 quasi-signal port' and the phase feedback signal! generates a signal 2 proportional to the phase difference between the gi, which is proportional to this phase difference, is used to remove harmonic components in the low-pass F wave filter LPF and amplify the phase error. And voltage controlled oscillation @
The VCO outputs nine frequencies proportional to the output H' of the low-frequency F frequency filter LPF, and the output of this voltage controlled oscillator vCO is connected to a frequency divider 35. Let N be the number of stages of the frequency divider 35. Ba,
The oscillation frequency of the voltage controlled oscillator VCO is N times the 11% phase reference. Here, N is selected as an arbitrary integer depending on the number of phases of the inverter circuit of the power conversion device 2. Frequency divider 35
Since the output of is the phase reference 11% port 1 of the phase error detection Fk41), the resonant frequency of the voltage controlled oscillator Is V It is automatically controlled so that Pi, L,
The function of one input port of LgI434 is to arbitrarily set the phase difference between the sand phase reference signal port and the phase reference signal port by giving a signal to the low-frequency V wave device LPF. .

Returning to diagram N1 again, to explain its operation, the 50 phase of the AC power supply is applied to the phase reference signal port of the PLL circuit 34, so the output frequency of the PLL circuit 34 is synchronized with the phase of the AC power supply 5. Therefore, the power conversion device 20 phase is also synchronized with the AC power supply 50 phase.

The power conversion device 2 is automatically controlled so that the secondary voltage 12 of the transformer 30 is always equal to the voltage reference 21, but when the switch 4 is open, the input and output of the error amplifier 33 are short-circuited by the switch 36, and the output is not activated. An active power control circuit that controls the phase of the power converter i12 based on the power deviation 33a is not formed.

At the same time as the switch 4 is set to the closed state 111, the switch 36 is turned on.
is opened, the short circuit between the input and output of the error amplifier 330 is released, and the phase of the power converter 2 is automatically controlled so that the active power of the power converter 2 becomes equal to the active power base $31.

The effects of voltage control and active power control by this power converter 2 will be explained using the vector diagram in FIG. 3.4. In FIG. 3, it is assumed that the voltage phases of the power converter 2 and the AC power supply 5 are completely equal, and the output voltage 211 of the power converter 2 is
The voltage at the connection point with II5 is transformed! If the secondary voltage 14 is E, then a voltage of E, -4 of the mstg vector is applied to the transformer IIs, so the current IL flowing through the transformer 3 changes the impedance of the transformer 3 to the reactor 71. It is represented by the vector IL. The power at this time is 69 reactive power, and the output voltage control of the power conversion device 2 is to transfer the reactive power. That is, in order to stabilize the voltage at the interconnection point, the power conversion device 24C and the secondary voltage 14 of the transformer 3 must be made equal to the voltage reference 21.

If the voltage in the AC region di5 is smaller than the voltage reference 21 and Φ, the reactive power 5 is supplied from the power converter 2 to the AC power source 5, and the 5e current $50 voltage is If it is higher than the voltage reference 21, it means that the reverse is occurring.

Also, as shown in the iris diagram 4, K11l! Assuming that the absolute values of the force converter 2 and the AC power source 5 (D-@pressure g, , g) are equal and there is a difference in voltage phase between the two, the voltage n applied to the transformer 3 is
, g, current IL is expressed by the vector shown in the figure. If the voltage phase θ is small, the voltage ja, - circle can be approximated at right angles to the voltage E1, 4. Therefore, the current IL is equal to the voltage h It is represented by a vector that has a phase difference of 180 degrees from @A. That is, the power at this time becomes active power. As is clear from FIG. 4, if the voltage phase of the AC power supply 5 is ahead of the power conversion wave r112, then
If the phase relationship is reversed, effective power will be supplied from the power converter 2 to the AC power source 5. That is, AC power supply 5
Assuming that the voltage and phase cannot be changed, it is difficult to change the voltage phase of the power converter 2 by controlling the reactive power and active power between the two power sources K and P. However, if the impedance of the transformer '43, which is the interconnection impedance, cannot be seen, the four voltages become large, and the voltage phase difference between the force converter 12 and the power source 5 becomes large, as shown in FIG. As such, among the orthogonal components to the voltage E1, the invalid component Ibl becomes large. In other words, since the effective power control of the power converter 2 causes a change in reactive power to occur at the same time, for example, when a power standard 31O installation value sudden change command is given, there is a sudden change in reactive power between AC IIc and H5. 'As a result of the exchange of power, the voltage at the interconnection point is forced to fluctuate according to changes in reactive power (1), and the stability of the voltage at the interconnection point is impaired.

(C) Object of the Invention The object of the present invention is to improve the above-mentioned drawbacks, and to provide a power converter that controls the power to be equal to a predetermined power standard, even against sudden changes in the power standard. An object of the present invention is to provide a power conversion device that maintains the voltage at a connection point with an AC power supply at a predetermined value and eliminates fluctuations.

(d) Structure of the Invention The present invention will be explained below with reference to an embodiment shown in FIG. 115. 1st ml in s5 diagram! Those with the same sign as the same function (0
It is 40. The point in 5gA that is true with Figure 1 is jl I
A signal synthesis circuit 42 that synthesizes the output signal 411 of the reactive power detection circuit 41 and the output signal 22J1 of the t-error amplifier 622 is provided in the constant voltage control system of the power conversion wave f2 indicating EK, and the output signal 42m is sent to the voltage control circuit 23. This is because it is used as an input.

(e) Effect of the invention In other words, in FIG. 5, if 616 is established in the AC 11, before the switch 4 is closed, the secondary voltage 12 of the transformer 3O is equal to the voltage reference 21 as in the conventional system shown in FIG. controlled to be equal. In a steady state when the switch 4 is closed, the error amplifier 33 of the active power control system outputs a constant output i.
'The voltage phase difference between the power converter 2 and the AC power source 5 applied to the LL circuit remains constant.

In state B, the reactive power detection circuit 41 continues to supply the output signal 41m of a constant value to the signal synthesis circuit 42. The difference amplifier 22 compares the secondary voltage 12 of the transformer 3 with the voltage reference 21, amplifies the difference 121m, and supplies the amplified signal to the signal synthesis circuit 42. Therefore, if the voltage reference 21 is set to a predetermined value in this state, the output will be 41 m in a situation where the output is constant.
is given to the Il composition diagram 42 as a negative value, so the output voltage of the power converter 2 is determined by the error amplifier 22+
Z) is kept constant by the output signal 22M.

17 When the active power control system operates when the switch 4 is turned on, or by changing the set value of the power standard 31, and makes the voltage phase of the power conversion device 2 higher than the voltage phase of the AC power ss.
II The change in reactive power that occurs is the reactive power product #5-Route 41
is given as a change in the output signal 41m of the signal synthesis circuit 42, and the pulse of the power converter 20 is immediately changed by the output signal 42aK of the signal synthesis circuit 42. For example, when the power conversion device 2 is being supplied with active power from the alternating current fi5 as shown in 4wA, and the setting of the power standard 31 is changed to decrease the active power, the phase angle between the two decreases in Fig. 4. Since the rounding reactive power also decreases, the output signal 42a of the p-signal synthesis circuit 42 is changed by the output signal 41M of the reactive power detection circuit 41, and the voltage of the power converter 2 is changed to decrease, thereby reducing the reactive power. Immediate response to transmission and reception is slowed down by suppressing fluctuations in voltage at interconnection points. Once the reactive power is stabilized, the output spiral pressure of the power conversion wave [2 is controlled to be constant p by the output signal 221 of the error amplifier 22, as described above.

(f) Other Embodiments Next, 51 in Figure 0 shows other embodiments of the grailK invention.
is a change amount detection circuit and the output signal 4 of the reactive power detection circuit 41
This circuit is mainly a differential detection circuit that extracts the amount of change of 1 m, and 51a is an output signal. That is, in this embodiment, instead of adding the output signal 411 of the reactive power detection circuit 41 shown in Figure 5 to the output of the error amplifier 22, the output signal 51m of the reactive power change detection circuit 51 is applied to the input of the error amplifier 22. , to operate only when the reactive power changes.
For example, when the reactive power decreases, the amount of change, i.e., the output signal 51a, is used to transiently operate the error amplification@22 with the gain, and the output signal 221 is used to increase the power conversion device wL2. By changing the voltage so that it becomes negative, the transfer and reception of p-reactive power can be performed immediately, and the same effect as in Figure #15 can be obtained.

Furthermore, the output voltage control of the power conversion device of the present invention is not limited to the inverter circuit; instead, a chisel cap circuit is added, and the inverter circuit fixes the ignition period.

The same effect can be obtained by using an ignition method that performs switching, and controlling the output and -pressure using a chopper circuit.

As described above, according to the present invention, in a power conversion system in which an AC power source of a power conversion device and a pond is connected, voltage fluctuations at interconnection points can be suppressed even in response to sudden changes in effective mineral capacity. A stable voltage can always be obtained.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the control method of a conventional AC interconnection system, Figure 2 is a specific circuit configuration diagram of the PLL circuit shown in Figure 1, and Figures 43 and 44 show the reactive power, active power, and active power, respectively. 5 is a block diagram showing one embodiment of the present invention, and Fig. s6 is a block diagram showing another embodiment of the present invention.
Power converter, 211... Output voltage, 3...
Transformer, 4... Switch, 5... AC 11
! Source, 11... Output 1 m, 12.14... Secondary voltage of transformer-3, 13... AC system voltage, 21...
Voltage standard, 141M, 2L...deviation, 22...
- difference amplifier, 22 a...output signal, 23...
'4 pressure control circuit, 31... active power reference, 32.
...Active power detection circuit, 33...Error amplification circuit,
33m...deviation, 34...PLL circuit,
35... Frequency divider, 36... Switch, 4
DESCRIPTION OF SYMBOLS 1... Effective power detection (2) path, 42... Signal synthesis circuit, 41m, 421... Output signal, 51... Change amount detection circuit, -sl[... Output signal. (7317) Agent: Patent Attorney Noriyuki Chika (
1 other person) Figure 2

Claims (2)

[Claims] (1) A voltage error that amplifies the deviation between the output voltage detection circuit and voltage setting circuit of the inverter circuit in a power conversion device that converts the output of a DC power source into AC using an inverter circuit or a circuit and an inverter circuit. It has a signal synthesis circuit that synthesizes the output signal of the amplifier circuit and the output signal of the reactive power detection circuit of the i/putter circuit, and the output voltage of the inverter circuit is controlled by the output signal of the cough signal synthesis circuit. Power conversion *Wt. (2) In a power converter that converts the output of a DC power source into AC using an inverter circuit, or a chip circuit and an inverter circuit, a voltage converter that amplifies the deviation between the output voltage detection circuit of the inverter circuit and the voltage setting path. The output 41 of the detection circuit that detects the amount of change in the reactive power of the inverter circuit is input to the expansion circuit! 1. A power conversion device, characterized in that the output voltage of the inverter circuit is controlled by the output signal of the voltage error amplification circuit.