JP2635660B2 - Control device for system DC interconnection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to a control device of a system DC interconnection device for transmitting and receiving power between AC systems using a voltage source type self-excited power converter. About.

(Prior Art) FIG. 6 is a diagram illustrating a voltage source system self-excited power converter (hereinafter referred to as a converter). FIG. 7 is a diagram for explaining an example of the configuration of the inverter main circuit constituting the converter. FIG. 8 is a diagram for explaining the operation principle of the inverter main circuit.

6 and 7, reference numeral 10 denotes an inverter, reference numeral 20 denotes a DC capacitor, reference numeral 30 denotes an interconnection reactor, and reference numeral 40 denotes an interconnection transformer. Reference numeral 50 denotes a DC power supply, and 100 denotes an AC system power supply (hereinafter referred to as a system).

In FIG. 7, GU, GV, GW, GX, GY and GZ are gate turn-off thyristors (hereinafter referred to as GTs) which are one type of controllable rectifier.
O, and DU, DV, DW, DX, DY, and DZ indicate diodes. PT and NT indicate DC terminals,
R, S and T indicate AC terminals, respectively.

How the power is adjusted by connecting the inverter main circuit composed of the inverter 10 and the DC capacitor 20 shown in FIG. 6 to the system 100 via the connection reactor 30 and the connection transformer 40 is described. The principle will be described with reference to FIG. The operating principle described in FIG. 8 is described in 216 of “Semiconductor Power Conversion Circuit” (published first edition on March 31, 1987), edited by the Institute of Electrical Engineers of Japan, Special Committee on Semiconductor Power Conversion Methods
A similar description can be seen from page 220 to page 220.

In FIG. 8, the inverter main circuit is indicated by 1. In addition, since both the interconnection reactor 30 and the interconnection transformer 40 in FIG. 6 are considered to be impedances, the interconnection impedance 30 is set to 2 in the combination of the interconnection reactor 30 and the interconnection transformer 40 in FIG. Interconnection transformers for ease of explanation
The transformation ratio of 40 is 1: 1.

In FIG. 8A, the inverter output voltage of the inverter main circuit 1 is V _IN , the system voltage of the system 100 is V _SY , the impedance of the interconnection impedance 2 is X, and the inverter main circuit is transmitted from the system 100 via the interconnection impedance 2. The current toward 1 is i, and the inverter output voltage with respect to the system voltage V _SY is V _IN
Is the phase difference angle of φ, the motion vector diagrams are (b) and (c).
It looks like the figure. (B) is a vector diagram in the case where the inverter main circuit 1 operates as a reactor. The amplitude of the inverter output voltage V _IN is smaller than the amplitude of the system voltage V _SY , and the interconnection impedance 2 has (V _SY −
V _IN ) is applied, and the current flowing through the interconnection impedance 2 becomes a current i having a component in phase with the system voltage V _SY and a component delayed by 90 °. This means that the inverter main circuit operates as a reactor and performs an operation of obtaining active power from the system 100.

 This relationship is represented by the following equation.

That the inverter output voltage V _IN amplitudes system voltage V _SY
If the phase of the inverter output voltage V _IN is smaller than the phase of the system voltage V _SY , the inverter main circuit 1
Operates as a reactor and performs an operation of obtaining active power from the system 100. (1) As apparent from (2), the amplitude of the inverter output voltage V _IN is smaller than the amplitude of the system voltage V _SY, the inverter output voltage V _IN
Main phase 1 consumes the delayed reactive power if the phase of system voltage V _{SY leads} the phase of system voltage V _SY.
An operation to output active power to 0 is performed.

In the equation (1), the phase difference angle φ is treated as a positive value when the phase of the inverter output voltage V _IN is ahead of the system voltage, and is treated as a negative value when the phase is delayed, and P is a negative value. When this is the case, it means that active power is being supplied from the inverter main circuit 1 to the system 100. Equation (2) indicates that when Q is negative, the inverter main circuit 1 performs a capacitor operation, and when Q is positive, the inverter main circuit 1 performs a reactor operation.

Figure 8 (c) shows the motion vectors in a case fully to the condition of the following formula amplitude V _IN of the inverter output voltage V _IN is the amplitude V _SY of the system voltage V _SY.

In this case, the current flowing through the interconnection impedance 2 becomes current i having a phase component with respect to the system voltage V _SY and 90 ° advances the component. This indicates that the inverter main circuit 1 operates as a capacitor and obtains active power from the system 100. Even when the equation (3) is satisfied, the inverter main circuit 1 operates as a capacitor and supplies active power to the system 100 when the phase difference angle φ is a positive value as is apparent from the equations (1) and (2). It is shown that.

Inverter output AC voltage V _IN and DC voltage E of DC power supply 50
It has the following relationship with _d .

M in the expression (4) is called a modulation degree and is a value from 0 to 1.0. As a method for adjusting the modulation degree M, there is a method called PWM control. The PWM control is for adjusting the AC output voltage of the inverter by adjusting the duration of the current supply to the GTO GU, GV, GW, GX, GY and GZ constituting the inverter main circuit of FIG.

By substituting equation (4) into equations (1) and (2), the following equations (5) and (6) are obtained.

(5) The modulation M to adjust the Fuhaba V _IN of phase difference angle φ and the inverter output voltage with respect to the system voltage _SY of the inverter output voltage _IN from equation (6), GTO GU inverter main circuit of Figure 7, GV, GW, G
It can be seen that electric power can be exchanged between the DC power supply 50 and the system 100 by adjusting the width of the energization time of X, GY, and GZ.

Conventionally, a rectifier using a thyristor, a battery, or the like has been often used for the DC power supply 50. As the DC power supply 50, the same as the converter 1000 in FIG. 6 can be used, and power can be obtained from a system different from the system 100 to be used as a DC power supply. Since the DC power supply cannot supply reactive power, it is considered to supply active power. When formula (5) is transformed, Becomes When using the converter 1000 as the DC power supply 50,
Active power P in order to constantly positive polarity DC voltage E _d is understood that there may be a negative phase difference angle φ when the active power P to the transducer from the positive That system is supplied. Conversely, when the active power P is negative, that is, when the active power P is supplied from the converter to the system, the phase difference angle φ may be made positive. Also it can be seen that it is sufficient to Msinφ a predetermined value in order to fix the DC voltage E _d be active power P is changed. Incidentally, when the converter 1000 is used as a DC power supply, the reactive power Q can be exchanged with the system. From equations (5) and (6) And the phase difference angle φ is obtained. That is, if the active power P and the reactive power Q are determined, the phase difference angle φ is determined, and the modulation degree M for setting the DC voltage _Ed to a predetermined value can be obtained by the equation (5).
Therefore, even when the converter 1000 is used as a DC power supply, reactive power can be transferred between the converter 1000 and the system.

As described above, the power transfer method of the method shown in FIG. 9 has been conventionally used. FIG. 9 is a diagram for explaining the configuration of a conventional example of a system interconnection device.

In FIG. 9, devices that perform the same functions as in FIG. 6 are denoted by the same reference numerals. 60 is a DC reactor, 71
Is a current transformer, 72 is a DC voltage detector, 73 is an active power detector,
81 denotes a gate control device, and 82 denotes a reactive power reference setting device. Reference numeral 91 denotes an error amplifier, 94 denotes a subtractor, and 96 denotes an active power reference setting device, which constitutes an active power control device 910 (hereinafter referred to as APR). 92 is an error amplifier, 95 is a subtractor, 97
Is a DC voltage reference setting device.
(Hereinafter referred to as AVR). 101 and 201 are systems, and 110 and 210 are converters.

In converter 110, active power P is detected by active power detector 73 from the AC current signal from AC device 71 and the AC voltage signal of the system. The active power setting unit 96 sets the active power reference P _dp
Is output. The subtractor 94 subtracts the active power P from the active power reference P _dp and outputs an error signal to the error amplifier 91. The error signal amplifier 91 outputs an active power command PAPR to the gate control device 81 according to the error signal. The APR 910 sets the active power P to the active power reference P by the operation of the subtractor 94 and the error amplifier 91.
_The active power command PAPR to be output to the gate control circuit 81 is determined so as to be equal to _dp . As the error signal amplifier, a circuit for performing a proportional-integral operation is often used, but a circuit for performing various operations is not limited thereto. The reactive power reference setting device 82 sends the reactive power command Qref ₁ to the gate control circuit 81.
Is output. The gate control circuit 81 is given by the equation (5) and the equation (6).
Determining the modulation M and the phase difference angle φ by equation P and Q the effective power command PAPR and reactive power command Qref ₁ respectively, each of the inverter main circuit 10 on the basis of these GTO
The gate signal that determines the duration of the element
Output to By the above operation, converter 110 is connected to system 101
And the active power P and the reactive power Q.

In the conversion device 210, the DC voltage E
_d is detected. DC voltage reference setter 97 is DC voltage reference E
Output _dp . Subtractor 95 subtracts the DC voltage E _d from DC voltage reference E _dp, and outputs an error signal to the error signal increase width 92. The error signal amplifier 92 outputs an active power command PAVR to the gate control circuit 81 according to the error signal. AVR920 subtracter 95
And by the action of error amplifier width 92, and determines the active power command PAVR to be outputted to the gate control circuit 81 so as to equalize the DC voltage E _d to the DC voltage reference E _dp. Error signal amplifier 92
A circuit that performs a proportional-plus-integral operation is often used as
Not limited to this, circuits for performing various operations are used.
Reactive power reference setter 82 outputs a reactive power command Qref ₂ to the gate control circuit 81. The gate control circuit 81 by (5) and (6) respectively power command PAVR, and reactive power command Qref ₂ P and Q of formula, the inverter main circuit 10 determines the modulation depth M and the phase difference angle φ A gate signal for determining the duration of energization of each GTO element is output to the inverter 10. By the above operation, converter 210 exchanges active power with system 201 so as to keep DC voltage _Ed constant, and exchanges reactive power Q with system 201.

In the description of FIG. 9 so far, the operation has been described as the power transfer between the converter 110 and the system 101 and the power transfer between the converter 210 and the system 201. But the converter 110
And the converter 210 are connected via the DC reactor 60 in each converter, and by the converter 210 operating as a DC constant voltage source, from the converter 210 to the converter 110 or vice versa. This is a system for transmitting and receiving active power to and from the conversion device 210. When the active power is transmitted from the converter 210 to the converter 110, the active power is transmitted from the system 210 to the system 101, and the converter 110 transmits the active power to the converter 101.
When the active power is sent to the system 201, the active power is transferred from the system 101 to the system 201.

The above relationship will be described with reference to FIG. The vertical axis of FIG. 10 is a DC voltage E _d, the horizontal axis represents the DC current I _d flowing in the direction of the converter 210 from Figure 9 of the converter 110 as a positive. Even if straight line Figure 10 is flowing in the negative direction even when the DC current I _d flows in the positive direction in which shows the operation characteristics of the converter 210, DC by the action of AVR920 in the conversion device 210 It indicates that it is operable to equalize the voltage E _d to the DC voltage reference E _dp set by DC voltage reference setter 97. That f point from a point in accordance with the direct current I _d is a positive value from a negative value, E _dp, b point and the DC voltage E _d E
_It moves to _dp . The curves and curves in FIG. 10 show the operation of the converter 110. The curves and curves operate such that the converter 110 makes the active power P that the converter 110 exchanges with the converter 210 under the action of the APR 910 equal to the active power reference P _dp set by the active power reference setter 96. It indicates that. The curve shows an operation curve when the active power reference P _dp is a positive value, and the curve shows an operation curve when the active power reference P _dp is a negative value. Active power P is expressed as by using a direct current I _d and the DC voltage _{E d P = E d × I} d (9). That curve and the curve has a (9) of P to be obtained by the P _dp, curve that is inversely proportional to the DC current I _d and the DC voltage E _d. Incidentally active power reference P _dp is the case of zero is a straight line passing through O and Z point and E _d of FIG. 10.

Now, a description will be given of the transfer of active power between converter 110 and converter 210 when active power reference P _dp of converter 110 is positive. In FIG. 10, converter 110 operates to operate on a curve, and converter 210 operates to operate on a straight line. For this reason, converter 110 DC voltage E _d is E _dp becomes, the converter 210 active power P
Is transmitted and received at the point b where _Pdp .
This indicates that active power is being transmitted from converter 110 to converter 210. Conversely, when the active power reference P _dp of the converter 110 is negative, the converter 110 and the converter 210 are operated at point f, which is the intersection of the straight line with the curve in FIG. 10, and the converter 110 Indicates that active power is being received from 210. When active power reference _Pdp is zero, converter 110 and converter 210 operate at point Z, and no active power is exchanged between the converters. However, even in this case, converter 110 is connected to system 1
01 and the converter 210 continue to operate to exchange reactive power with the system 201, respectively.

(Problems to be Solved by the Invention) The conventional example shown in FIG. 9 has the following problems. That is, when the converter 210 that performs the constant DC voltage control stops operating due to a failure or the like, the converter 110 that performs the constant active power control can perform an operation of exchanging the reactive power with the system 101. Despite this, the operation must be stopped. Of course, even if the converter 110 performing the constant active power control stops operating, the converter 210 performing the constant DC voltage control can continue operation at the point Z where the DC current becomes zero in FIG. Reactive power can be exchanged with the system 201.

An object of the present invention is to solve the above-mentioned disadvantages of the conventional example. A plurality of converters are connected in parallel via a DC terminal or a DC line, and active power is exchanged between the converters. The purpose of the present invention is to provide a control device of a system direct-current interconnection device that can stably continue the operation of the remaining conversion devices even if there is a conversion device that suddenly stops operating in the existing system interconnection device And

[Structure of the Invention] (Means for Solving the Problems) Means for achieving the above object of the present invention are as follows.

A control system in which a plurality of conversion elements are connected in parallel via DC terminals or DC lines, and active power is exchanged between converters. The constant power control and the constant DC voltage control for controlling the device to make the active power exchanged with the AC system equal to the active power reference value and the DC voltage constant control and the active power constant control for controlling the DC voltage to be equal to the DC voltage reference value. A selector for selecting the maximum value or the minimum value of the output signal and the output signal of the DC voltage constant control is set, and the selector of each converter performing the interconnection operation is set to select the maximum value. If so, the DC voltage reference value of one converter is set to be greater than or equal to the DC voltage reference value of the remaining converters, and the selector of each converter performing the interconnection operation is set. When the minimum value is set to be selected, the DC voltage reference value of one converter is set to be smaller than or equal to the DC voltage reference value of the remaining converters. Control device.

(Operation) How the means for solving the above problem operates will be described. When the maximum value is selected by the selector of each converter that performs the interconnection operation, the DC voltage reference value is set higher than the DC voltage reference values of the remaining converters. To control the DC voltage constant, and in the remaining converters, the active power is controlled to be constant by the constant active power control.

When the selector of each converter performing the interconnected operation selects the minimum value, the DC voltage reference value is set lower than the DC voltage reference values of the remaining converters. To control the DC voltage constant, and in the remaining converters, the active power is controlled to be constant by the constant active power control.

The operation of the means for solving the above problem will be described with reference to an embodiment.

(Embodiment) FIG. 1 is a diagram for explaining the configuration of an embodiment according to the present invention, and FIGS. 2 and 3 are diagrams for explaining the operation of the embodiment.

In FIG. 1, devices performing the same functions as in FIG. 9 are denoted by the same reference numerals. 90 indicates an active power control device, and 93 indicates a selector.

A case where the selector 93 is set to select the minimum value will be described. Converter 110 and converter 210 have an active power controller 90 that performs the same function. The active power control device 90 includes an active power constant control 910, a DC voltage constant control 920, and a selector 930. Active power command PAP that controls to match the active power reference P _dp active power P from active power constant control 910 active power detector 73
Outputs P to the selector 93, and outputs a power command PAVR to controls to the DC voltage E _d from DC voltage constant control 920 DC voltage detector 72 to coincide with DC voltage reference E _dp to the selector 93. Selector 93 selects and outputs what the minimum of the active power command PAPR with active power command PAVR to the gate control 81 as active power command P _ref. Gate control 81 is active power command
Based on P _ref and the reactive power command Q _ref from the reactive power reference setting unit 82, a gate signal for determining the duration of the current supply to the inverter 10 is output.

Reactive power reference conversion device 110 and the active power reference P _dy of converter 210 and the DC voltage reference E _dp Q _ref and the real power command P _ref is often different. For this reason, P _{dp
Are referred} to as P _dp1 , E _{dp is referred} to as E _dp1 , Q _{ref is referred} to as Q _ref1 , and P _ref is referred to as P _ref1. P _dp in the converter 210 is referred to as P _dp2 , E _{dp is referred} to as E _dp2 , and Q _{ref is referred} to as Q _ref2 , P _ref.
Is set to _Pref2 respectively.

_{Either the} DC voltage reference E _dp1 or E _dp2 may be smaller, but here, the DC voltage reference E _dp1 is described as being set to be larger than the DC voltage reference E _dp2 . In this case, it is assumed that the active power references P _dp1 and P _dp2 are set to the same positive value.

 The operation of the embodiment will be described with reference to FIG.

FIG. 2 shows the DC voltage E _d on the vertical axis and the DC current I _d from the converter 110 to the converter 210 as positive, as in FIG. Are shown as a solid line A and a dotted line A, respectively.

First, the solid line A indicating the operation of the conversion device 110 will be described. As the DC current _Id changes from a negative value to a positive value, a
Move on a straight line from point to point b via point Z1. AVR920 this time converter 110 is outputting active power command value PAVR to equal the DC voltage E _d to the DC voltage reference value E _dp1. Since APR910 within converter 110 is active power reference P _dp1 has a positive value, the product of the DC current I _d and the DC voltage E _d passing through the point b and the point x and the point c as an active power reference P _dp1 The active power command value PAPR is output so that However, since the active power command value PAPR is _{equal to} or less than the active power reference P _dp1 from the point a to the point just before reaching the point b via the point Z1, the conversion device
The output of the subtractor 94 in 110 is positive, and the operational amplifier 9
Due to the operation of 1, a value larger than the active power command value PAVR is output. Thus, selector 93 selects the minimum value in converter 110 outputs active power command value PAVR as active power command P _ref1 to the gate control circuit 81. The operation from the point b to the point c via the point x is performed when the converter 110
If an attempt is made to pass a DC current to the converter 210 at a point or higher than the DC current, the active power command PAVR which is the output of the AVR 920 in the converter 110 is the active power designation which is the output of the APR 910.
Greater than PAPR. Thus the DC voltage E _d may be a DC voltage reference E _dp1.

In other words, the row by active power command PAPR from APR910 is smaller than active power command PAVR from AVR920, is outputted is selected as the real power command PAPR is the real power command P _ref1 by selector 93 to the gate control circuit 81 Operation.

As described above, when the converter 110 increases the DC current _Id from the negative value to the positive value, the converter 110 reaches the point b through the points a and Z1 in FIG. It can be seen that the operation moves to the point c.

Next, the dotted line A indicating the operation of the converter 210 will be described. In the FIG. 2 is a direct current I _d flowing from converter 110 to converter 210 is positive. This means that the converter 110
This indicates that the state where active power P is being transmitted from the converter to the converter 110 is positive, and that the converter sends out AC power as DC power, that is, an operation called forward conversion. Conversely, the operation of the converter sending out DC power as AC power is called reverse conversion.
When the inverter 110 performs the inverse conversion, the DC current _Id is negative. The conversion device 210 performs the inverse conversion operation when the conversion device 110 performs the forward conversion, and performs the forward conversion operation when the conversion device 110 performs the inverse conversion operation. That is, the conversion device 110 and the conversion device 210 perform the operations of the forward conversion and the inverse conversion in reverse. Therefore, in FIG.
_{Assuming that} the positive direction of the DC voltage Id with respect to 0 is the direction from the converter 210 to the converter 110 as positive, the operation of the converter 210 is represented on the same drawing (FIG. 2) as a dotted line A.
Since the DC voltage reference value in the conversion device 210 is E _dp2 , if the DC current I _d is increased from the negative to the positive with respect to the conversion device 210, from the point a1 by the action of the AVR 920 in the conversion device 210. It reaches point b1 through point Z2, and DC current I _d
Transfer the operating point greatly them if converter DC voltage product is active power reference equal curve on the P _dp2 of E _d and the DC current I _d by the action of APR910 in 210 in a direction toward the c1 point from point b1 go.

Although the operations of the converter 110 and the converter 210 have been described with reference to FIG.
Are interconnected and exchange active power. When the converters 110 and 210 are performing the operations of the solid line A and the dotted line A shown in FIG. 2, the operation is performed at the point x in FIG. This means that the converter 110 converts the DC voltage _Ed to E
and attempt to raise _dp1, for converting device 210 attempts to decrement the DC voltage E _d to E _dp2, both converter 210 converter 110 to try to increase towards the converter 210 the DC current I _d from the converter 110 . However, the active power set value _{Pref1 of the} converter 110
Is positive, converter 110 converts DC voltage E _d to E
_{Move the} operating point to point x, which _drops to _dp2 . As a result, the conversion device 210 also operates at the point x under the action of the AVR 910. This situation is sent to converter 210 active power from the converter 110 the DC voltage E _d as E _dp2.

Even converter 110 stops the operation when the converter 110 and the converter 210 is performing the operation in point x of FIG. 2, converter 210 is the DC current I _d from the converter 110 becomes zero , The operating point can be moved to the Z2 point and the operation can be continued. Also, even if the converter 210 stops operating, the converter 110
When the current to the converter 210 becomes zero, the operating point can be shifted to the point Z1 and the operation can be continued.

This shows an effect that, even when one of the two converters that have been linked stops operating, the remaining one converter can perform an operation of exchanging reactive power with the system.

FIG. 3 is a diagram for explaining the operation of the embodiment when the selector 93 in FIG. 1 is set to select the maximum value.
In this case, the DC voltage reference E _dp2 of the converter 210 is
The description will be made on the _{assumption that the} reference voltage is set to be larger than the DC voltage reference _Edp1 . Further, for convenience of explanation, active power reference P _dp2 of active power reference P _dp1 also converting apparatus 210 of the converter 110 is also a negative value. The solid line in FIG. 3 shows the operation of the converter 110, and the dotted line shows the operation of the converter 210. In FIG. 3, when both converter 110 and converter 210 are operating, point y is the operating point. When converter 210 is stopped, converter 110 can operate at point Z1, and converter 110 can operate at point Z1. When stopped, converter 210 indicates that operation can be performed at point Z2. In this case as well, even if one of the two converters that are connected stops operating,
It can be seen that one of the converters can be operated to exchange reactive power with the system.

4 and 5 are views for explaining still another embodiment. FIG. 4 is a diagram showing a system interconnection device including three converters connected in parallel via a DC terminal to transfer active power. FIG. 5 is a diagram for explaining the operation of each converter shown in FIG. In FIG. 4, devices having the same functions as those in FIG. 1 are denoted by the same reference numerals. 300 indicates a system, and 310 indicates a converter. The converter 310 has the same configuration as the converter 110 or the converter 210 of FIG. 1, but the active power reference P _dp is set to P _dp3 , and the DC voltage reference E _dp is set to E _dp3 , Reactive power standard Q
_ref is set to Q _ref3 .

FIG. 5 shows that each selector in converter 110, converter 210 and converter 310 selects the minimum value, and the DC voltage reference is E _dp1 > E.
_{This shows a situation in} which _dp2 > _Edp3 is set, and each active power reference _Pdp1 , _Pdp2, and _Pdp3 is set to a positive value. In FIG. 5, the solid line A indicates the operation of the converter 110, the dotted line A indicates the operation of the converter 210, and the one-dot chain line C indicates the operation of the converter 310. Drawn in the direction opposite to the direct current I _d in the direction of the converter 110 and the converter 210 of the converter 310 only the DC current I _d that DC voltage reference E _dp similarly to FIG. 2 is set to the minimum is there.
When the converter 110, the converter 210, and the converter 310 are operating in an interconnected manner, the operating point of the converter 110 becomes the x1 point, performs forward conversion, flows the DC current I _d1, and operates the operating point of the converter 210. Is the x2 point, and the DC current I _d2 is passed by performing the forward conversion. Converter 310 is a DC voltage DC current I _dp3 of the sum of the direct current I _d1 and I _d2 by performing an inverse transform while maintaining E _d to E _dp3
Have gained. That is, the active power P represented by P = (I _d1 + I _d2 ) × E _dp3 is sent to the system 300.

Even if converter 110 stops operating in this operating state, converter 210 and converter 310 can continue operation at x2 points. Further, even if converter 210 stops operating, converter 210 and converter 310 can operate at x1 point. When conversion device 310 stops operating, conversion device 110 and conversion device 210 operate in the second
As shown in the figure, the point x in FIG. 2 is the operating point. Incidentally, when the conversion device 310 stops operating, the operation of the conversion device 210 changes from forward conversion to reverse conversion, and there are some means for preventing this. One of them is to make the DC voltage reference values E _dp of the converters 110 and 210 equal to E _dp.
This is the method to set to _dp1 . This allows the conversion device 310
Of the converter 110 and the converter 210 when the
By the action of R, and operates to E _dp1 the DC voltage E _d both converter, without transfer of active power P, converter
The operation of transmitting and receiving the reactive power between 110 and system 100 and between converter 210 and system 200 can be continued.

[Effects of the Invention] As described above, the present invention has the following effects.

A control system in which a plurality of conversion elements are connected in parallel via DC terminals or DC lines, and active power is exchanged between converters. The constant power control and the constant DC voltage control for controlling the device to make the active power exchanged with the AC system equal to the active power reference value and the DC voltage constant control and the active power constant control for controlling the DC voltage to be equal to the DC voltage reference value. A selector for selecting the maximum value or the minimum value of the output signal and the output signal of the DC voltage constant control is set, and the selector of each converter performing the interconnection operation is set to select the maximum value. In this case, the DC voltage reference value of one converter is controlled to be greater than or equal to the DC voltage reference value of the other converters, and the selection of each converter performing the interconnection operation is performed. The DC voltage reference value of one converter if the vessel is configured to select a minimum value,
By configuring the control device of the system interconnection device so as to have means for controlling the DC voltage to be smaller or equal to the DC voltage reference value of the remaining converters, one of the converters performing the interconnection operation may fail. Thus, even if the operation is stopped, the operation can be performed without stopping the remaining converters.

In the above description, the operation of one converter that is performing the interconnection operation is stopped. However, even when only one converter can be operated, the operation of one converter can be continued.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a configuration example of a system interconnection device according to one embodiment of the present invention, FIG. 2 is a diagram for explaining the operation of the embodiment of FIG. 1, and FIG. 3 is an embodiment of FIG. FIG. 4 is a diagram for explaining an operation different from that of FIG. 2; FIG. 4 is a diagram for explaining a configuration of a system interconnection device using three voltage source type self-excited converters for explaining another embodiment according to the present invention; 5 is a diagram for explaining the operation of the embodiment of FIG. 4, FIG. 6 is a diagram for explaining a voltage source type self-excited converter, and FIG. 7 is an inverter main circuit constituting the voltage source type self-excited converter. FIG. 8 is a diagram for explaining the operation principle of the inverter main circuit shown in FIG. 7, FIG. 9 is a diagram for explaining the configuration of a conventional example of a system interconnection device, and FIG. Ninth
It is a figure explaining operation | movement of the grid connection apparatus of the conventional example of the figure. 100, 200 AC system, 110, 210 Voltage source type self-excited converter, 10 Inverter, 20 DC capacitor, 30
... interconnection reactor, 40 ... transformer, 60 ... DC reactor, 71 ... current transformer, 72 ... DC voltage detector, 73 ... active power detector, 81 ... gate control circuit, 82 ... Reactive power reference setting device, 90: Active power control device, 910: Active power constant control device, 920: DC voltage constant control device, 91, 92 ...
... Error amplifier, 93 ... Selector, 94,95 ... Subtractor, 96 ...
… Active power reference setting device, 97 …… DC voltage reference setting device.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Haruhisa Inokuchi 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant, Inc. (56) References JP-A-59-92729 (JP, A) JP-A-63-7141 (JP, A) JP-A-49-32657 (JP, A)

Claims (2)

(57) [Claims] A voltage source type self-excited power converter for converting AC power to DC power and vice versa for converting DC power to AC power and transmitting and receiving power between an AC system and a DC line. A plurality of power source type self-excited power converters are connected in parallel via a DC terminal or via a DC line, and a system interconnection device for exchanging power between the respective voltage source type self-excited power converters. Active power constant control that controls the active power control device that is exchanged with the AC system by the voltage source type self-excited converter so that the active power that is exchanged with the AC system is equal to the active power reference value, and the DC voltage is the DC voltage reference value And the minimum value of the output signal of the constant DC voltage control and the output signal of the constant DC voltage control and the output signal of the constant DC voltage control, and the voltage source type self-excited converter exchanges with the AC system. Active power Constituted by a selector which determines a value,
Of the control devices of each voltage source type self-excited power converter, the DC voltage reference value of one of the control devices of the voltage source type self-excited power converter performing the interconnection operation is connected to the remaining devices performing the interconnection operation. A control device for a system DC interconnection device, which is set to be smaller or equal to a DC voltage reference value of a control device of a voltage source type self-excited power converter. 2. A voltage source type self-excited power converter for converting AC power to DC power and vice versa for converting DC power to AC power and transmitting and receiving power between an AC system and a DC line. A plurality of power source type self-excited power converters are connected in parallel via a DC terminal or via a DC line, and a system interconnection device for exchanging power between the respective voltage source type self-excited power converters. Active power constant control that controls the active power control device that is exchanged with the AC system by the voltage source type self-excited converter so that the active power that is exchanged with the AC system is equal to the active power reference value, and the DC voltage is the DC voltage reference value And the minimum value of the output signal of the constant DC voltage control and the output signal of the constant DC voltage control and the output signal of the constant DC voltage control, and the voltage source type self-excited converter exchanges with the AC system. Active power Constituted by a selector which determines a value,
Of the control devices of each voltage source type self-excited power converter, the DC voltage reference value of one of the control devices of the voltage source type self-excited power converter performing the interconnection operation is connected to the remaining devices performing the interconnection operation. A control device for a system DC interconnection device, which is set to be larger or equal to a DC voltage reference value of a control device of a voltage source type self-excited power converter.