JPH09191567A - Controller for self-excited ac/dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of unstable operation due to commutation failure of an inverter in a separately excited d.c. power transmission system by controlling so as to increase an effective power. SOLUTION: If a phase advance control circuit 22 comes into action for some reason such as the large voltage strain of an a.c. system 1 connected to a self-excited a.c./d.c. converter 3 and a separately excited a.c./d.c. converter 19 with inverter operation of the separately excited a.c./d.c. converter 19, phase advance control is made for separately excited a.c./d.c. converter 19. A phase advance command signal 20 is given to an effective power setting value calculating circuit 18 used in the self-excited a.c./d.c. converter, so that a switching circuit is switched and the interchange power of a self-excited d.c. power transmission system increases by a fixed amount more than a predetermined value. By increasing the interchange power, power drop of a separately excited power transmission system is compensated. As a result, a change in the interchange power of a combination of the separately excited power transmission system and a self-excited d.c. power transmission system is reduced, thus it is possible to restrain fluctuation given to the a.c. system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a self-excited type applied to an asynchronous interconnection system, a frequency conversion system, an inverter device for converting the power of a DC power supply into AC power, or a static var compensator in a power system. The present invention relates to a control device for an AC / DC converter.

[0002]

2. Description of the Related Art In recent years, self-excited AC / DC converters using self-extinguishing elements such as GTO thyristors have come to be applied to electric power systems such as DC power transmission, inverter devices and static var compensators. ing.

FIG. 19 shows a configuration of a DC power transmission system using a self-excited AC / DC converter as a typical example.

As shown in FIG. 19, a self-excited AC / DC converter 3 is connected to an AC system 1 via a converter transformer 2. The self-excited AC / DC converter 3 is composed of a 6-phase or 12-phase bridge circuit in which a GTO thyristor and a diode are connected in antiparallel to each arm.

A DC capacitor 4 is connected to the DC end of the self-exciting AC / DC converter 3, one end of which is connected to the DC terminal A and the other end is connected to the DC terminal B. This DC terminal A and B
Is connected to a self-excited AC / DC converter 3'having the same configuration as the self-excited AC / DC converter 3, and its AC end side is connected to another AC system 1'through a converter transformer 2 '.

The configuration of FIG. 19 is for a DC power transmission system, but in the case of a DC power transmission device, DC terminals A and B are used.
A DC power source such as a battery is connected between them, and in the case of a reactive power compensator, the DC terminals A and B are open.

In the above DC transmission system, one of the self-excited AC / DC converters 3 or 3'is operated for forward conversion and the other is operated for inverse conversion. As for the control device and the detection device, both the converter 3 and the converter 3 ′ have the same configuration, and therefore, FIG.
In FIG. 9, only the self-excited AC / DC converter 3 is shown.

On the side of the self-excited AC / DC converter 3, a DC voltage detector 5 connected between both terminals of a DC capacitor 4 detects a DC voltage, and this DC voltage and a DC voltage set value E are detected.
The dref is compared and the deviation is input to the DC voltage controller 6.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the active power detector 7. The active power detector 7 detects active power from the AC current and the AC voltage, compares the active power with the active power set value Pref, and inputs the deviation to the active power controller 8.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the reactive power detector 9. The reactive power detector 9 detects the reactive power from the AC current and the AC voltage, compares it with the reactive power set value Qref, and inputs the deviation to the reactive power controller 10.

In the DC voltage controller 6, the active power controller 8 and the reactive power controller 10, the output signals are controlled so that the respective detected values and set values become equal. The output of the DC voltage controller 6 and the output of the active power controller 8 are the selection circuit 11
And one of the outputs is selected.

The output of the selection circuit 11 and the output of the reactive power controller 10 are given to the arithmetic circuit 12. The arithmetic circuit 12 calculates the phase angle φ and the control rate Cm of the PWM control signal based on the reactive power output given from the reactive power controller 10 and the active power output given from the selection circuit 11,
It is given to the PWM control circuit 13. The PWM control circuit 13 determines the phase angle φ, the control rate Cm, and the generation timing of the ON pulse and the OFF pulse given to the GTO. Pulse generation circuit 1
At 4, the on-pulse and the off-pulse for each arm of the self-excited AC / DC converter 3 are generated by these signals and given to the self-excited AC / DC converter 3. In this self-excited AC / DC converter 3,
Operation is performed by turning on / off the GTO thyristor of each arm by this pulse.

By using such a control system,
In the DC power transmission system, the electric power of the active power set value Pref is exchanged from the forward converter side to the inverse converter side, and each converter outputs the reactive power of the reactive power set value Qref as the operation. Be done.

Here, the reactive power has its own set value on the forward converter side and the inverse converter side and is independently controlled, but the active power is controlled by a common value on both ends. Specifically, in one of the self-excited AC / DC converter 3 and the self-excited AC / DC converter 3 ', the output of the active power controller 8 is selected by the selection circuit 11 to directly control the active power, and the DC voltage is applied at the other end. By selecting the output of the controller 6 and controlling it so that the DC voltage becomes constant, an operation is performed in which the DC power is kept constant and the power corresponding to the given active power set value Pref is exchanged. .

Further, in the conventional example shown in FIG. 19, the reactive power controller 10 controls the reactive power output to be constant according to the given reactive power set value Qref. In some cases, a control circuit that controls the reactive power so as to keep the voltage constant is used. That is,
An AC voltage control circuit 16 as shown in FIG. 20 is provided in place of the reactive power detector 9 and the reactive power controller 10 shown in FIG. 19, and the AC voltage set value Vref and the AC voltage detected by the AC voltage detector 15 are provided. When the detected value is larger than the set value, the reactive power value is changed in the negative direction, that is, in the delay direction, and when the detected value is smaller than the set value, the reactive power value is positive. The direction, that is, the forward direction, is changed. By giving the signal thus obtained to the arithmetic circuit 12 to calculate the phase angle φ and the control rate Cm,
The reactive power output of the converter is controlled so that the value of the AC voltage is equal to the set value Vref. Since the reactive power is controlled independently on the forward converter side and the inverse converter side, it is possible to perform the reactive power constant control on one side and the AC voltage constant control on the other side.

[0016]

[Problems to be Solved by the Invention] FIG. 19 or FIG.
When a conventional control device for a self-excited AC / DC converter as shown in Fig. 0 is used, it is a system in which a separately-excited DC transmission system is installed in parallel with a self-excited DC transmission system. When the phase lead control is performed in the DC transmission system, the DC voltage of the separately excited DC transmission system decreases and the interchange power becomes small.On the other hand, in the self-excited DC transmission system, the active power is controlled to be constant, so The total amount of interchangeable power, including the DC transmission system and the separately excited DC transmission system, decreases.

Further, the self-excited DC transmission system is characterized in that it can control active power and reactive power in a restricted manner, but it is a system in which a separately excited DC transmission system is installed in parallel with the self-excited DC transmission system. When the active power or reactive power of the transmission system is changed at high speed, the voltage of the connected AC system fluctuates or is distorted, which causes the reverse converter of the separately excited DC transmission system to commutate and stabilize. You may not be able to drive.

Further, a system in which a separately-excited DC transmission system is installed in parallel with a self-excited DC transmission system using a conventional controller for performing constant reactive power control as shown in FIG. When the phase advance control operates in the inverse converter of the separately excited DC transmission system, the reactive power consumed by the separately excited AC / DC converter increases, that is, the reactive power output changes in the delay direction, while the self-excited AC / DC converter changes. Since it continues to output the same reactive power as before, there is a possibility that the AC voltage will drop and the separately excited AC / DC converter will fail to commutate and will not be able to operate stably.

Further, in a system in which a separately-excited DC transmission system is installed in parallel with a self-excited DC transmission system using a conventional controller for performing constant AC voltage control as shown in FIG. In the AC system on the side to which the reverse converter of the system is connected, the AC voltage rises when a capacitor element such as a power capacitor is turned on.Therefore, the self-excited AC / DC converter consumes reactive power due to constant AC voltage control. Is increased, that is, the operation is performed in the delay direction to decrease the AC voltage.

On the other hand, the AC voltage is distorted when the capacitor is turned on, and the reactive voltage consumption of the self-excited AC / DC converter increases, which causes the AC voltage to decrease.
There is a possibility that the separately-excited inverse converter may not operate stably due to commutation failure.

The present invention is a system in which a self-excited DC transmission system and a separately-excited DC transmission system are installed in parallel, and the operation of the inverse converter of the separately-excited DC transmission system becomes unstable due to commutation failure. The first purpose is to prevent it, and in a system in which the self-excited DC transmission system and the separately excited DC transmission system are installed in parallel, the interchange power that combines the self-excited DC transmission system and the separately excited DC transmission system is made constant. The second purpose is to keep it running, and the third purpose is to prevent AC overvoltage at the time of accident recovery when an accident occurs in the AC system to which the self-excited AC / DC converter is connected. It is to provide a control device for a self-excited AC / DC converter.

[0022]

As shown in FIG. 1, a control device for a self-excited AC / DC converter according to the invention according to claim 1 has a self-excited DC transmission system and a separately excited DC transmission system installed in parallel. , AC system 1 and AC system 1'by both DC transmission systems
In a system that is accommodating power between the two, when the separately excited AC / DC converter 19 or 19 ′ during the operation of the inverse converter performs so-called phase advance control to forcibly advance the phase of the firing angle,
The command signal 20 or 20 'for the phase advance control is given to the active power set value calculation circuit 18, and the value of the active power set value used in the converter control devices 17, 17' of the self-excited DC transmission system is set to a predetermined value. Control by increasing by ΔPref more than that of the self-excited DC transmission system, thereby increasing the interchange power by the self-excited DC transmission system and compensating for the decrease in the power interchange amount of the separately-excited DC transmission system due to the operation of the phase advance control. Also, a circuit for controlling the self-excited DC power transmission system is provided so as to prevent a decrease in the amount of power interchange, which includes the separately-excited DC power transmission system.

A control device for a self-excited AC / DC converter according to a second aspect of the invention is a system in which a self-excited DC transmission system and a separately excited DC transmission system are installed in parallel in FIG.
The operating powers PL and PL 'of the separately excited DC power transmission system are detected and given to the active power set value calculation circuit 18, and the set value P of the interchange power combining the self-excited DC power transmission system and the separately excited DC power transmission system is set.
By giving a value obtained by subtracting PL or PL 'from refx to the active power controller 8 in the converter control devices 17 and 17' as active power set values PrefA and PrefB of the self-excited DC power transmission system, the self-excited DC power transmission system is provided. And a circuit for controlling the separately-excited DC power transmission system so as to operate while maintaining a constant set value Prefx of the interchange power.

A control device for a self-excited AC / DC converter according to a third aspect of the invention is a system in which a self-excited DC transmission system and a separately excited DC transmission system are installed in parallel in FIG.
When the active power set values PrefA and PrefB of the self-excited DC transmission system are given to the active power controller 10 in the converter control devices 17 and 17 ', the active power set values Prefo given from the outside have different time constants. The DC current set value Idp of the separately excited DC transmission system is given to a plurality of first-order delay circuits 44.
By switching the switch circuit 45 according to the value of and selecting one of the outputs of the first-order lag circuit 44, when the active power set value Prefo given from the outside changes, it is actually sent to the converter control device. The circuit includes a circuit for switching and controlling the speed at which the given active power set values PresA and PrefB change in accordance with the interchange power of the separately excited DC power transmission system.

In the control device for a self-excited AC / DC converter of the invention according to claim 4, the self-excited AC / DC converter 3 and the separately excited AC / DC converter 19 are connected to the same AC bus in FIG.
When the separately excited AC / DC converter 19 performs so-called phase advance control to forcibly advance the phase of the firing angle, the reactive power set value Qref of the self-excited AC / DC converter is changed by the command signal 20 of the phase advance control. By adding a constant value ΔQref to make the value of the reactive power output larger than the previous value, that is, in the direction of the leading reactive power, the reactive power consumption increased by the phase advance control of the separately excited AC / DC converter is compensated and the AC is compensated. It is provided with a circuit for controlling the voltage drop and further enhancing the commutation failure prevention effect of the separately excited AC / DC converter.

In the control device for a self-excited AC / DC converter of the invention according to claim 5, the self-excited AC / DC converter 3 and the separately excited AC / DC converter 19 are connected to the same AC bus in FIG.
When the power condenser 65 is closed by the circuit breaker 64 in the vicinity thereof, the closing command signal 66 given to the circuit breaker 64 and the operating condition signal 50 of the separately excited AC / DC converter 19 are given to the limit value control circuit 67. Limit value control circuit 6
In No. 7, the limiter circuit 68 of the AC voltage control device 16 uses the logical product condition of the state signal that the breaker closing command signal 66 is turned on and that the separately excited AC / DC converter 19 is operating as an inverse converter. By changing the minimum limit value to be output to a value larger than the steady-state value, the reactive power output of the self-excited AC / DC converter 3 will increase even if the AC voltage rises for a certain time after the capacitor is turned on. A circuit provided with a circuit for restricting operation in a largely negative direction, that is, a direction in which reactive power is consumed, and for preventing commutation failure of the separately excited DC converter 19 due to voltage distortion caused by turning on a capacitor. Is.

The control device for a self-excited AC / DC converter of the invention according to claim 6 shows the magnitude of the AC bus voltage connected to the self-excited AC / DC converter 3 performing AC voltage control in FIG. When the voltage is monitored by the undervoltage relay 78 and the magnitude thereof drops below a certain value, the maximum limit value Qmax output from the limiter circuit 68 of the AC voltage control circuit 16, that is, the limit value in the direction of increasing the AC voltage is set. By lowering and changing in the zero direction, a circuit is provided so as to prevent the reactive power output from becoming a large value and the overvoltage from being generated when the AC voltage is recovered.

Therefore, in the control device for a self-excited AC / DC converter of the invention corresponding to each of the above claims, the following operational effects can be obtained.

In the invention corresponding to claim 1, when the interchange power is reduced due to the phase advance control of the inverse converter of the separately excited DC power transmission system connected in parallel, the separately excited DC power transmission is performed. The power interchange amount of the self-excited DC transmission system is increased so as to compensate for the power decrease of the system, and the combined operation of the self-excited DC transmission system and the separately-excited DC transmission system is operated to maintain a constant power interchange amount.

According to the second aspect of the invention, the combined operation of the separately-excited DC transmission system and the self-excited DC transmission system connected in parallel operates so as to keep the amount of power interchange constant.

In the invention corresponding to claim 3, the operating speed when the operating point of the self-excited AC / DC converter is changed according to the operating point of the separately excited DC transmission system connected in parallel is changed. It operates so as to start, stop, and change the operating point of the self-excited DC transmission system as fast as possible within the range that does not disturb the excited DC transmission system.

In the invention according to claim 4, when the inverse converter of the separately excited DC transmission system installed in the vicinity performs phase advance control for preventing commutation failure, the self-excited AC / DC converter is used. The reactive power output of 1 is increased, that is, the AC voltage is controlled to increase, and the operation of preventing commutation failure is further enhanced.

In the invention according to claim 5, a limiter is provided so that the reactive power output of the self-excited AC / DC converter does not decrease when the capacitor is turned on, that is, the AC voltage does not decrease. By operating, it operates to prevent commutation failure of the other separately excited AC / DC converter.

In the invention according to claim 6, the limiter is operated so that the reactive power output does not increase in the event of a ground fault or a short-circuit fault in the AC system. It works to prevent overvoltage.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of a control device for a self-excited AC / DC converter according to the present invention.

As shown in FIG. 1, a self-excited AC / DC converter 3 is connected to an AC bus 1 via a converter transformer 2 as in the conventional device.
It is connected to the. A capacitor 4 is connected to the DC end side of the self-excited AC / DC converter 3, one end of which is connected to the DC terminal A and the other end is connected to the DC terminal B. A self-excited AC / DC converter 3'having the same configuration as the self-excited AC / DC converter 3 is connected to the DC terminals A and B, and its AC end side is connected to an AC bus 1'through a converter transformer 2 '. There is.

The self-excited AC / DC converter 3 is a converter controller 17
In addition, the self-excited AC / DC converter 3'is controlled by the converter controller 17 '. One of the self-excited AC / DC converters is forward-converted, and the other is reverse-converted, so that the AC Power interchange is performed between the grids 1 and 1 '.

In the converter control device 17, the DC voltage is detected by the DC voltage detector 5 connected between both terminals of the DC capacitor 4, and this DC voltage is compared with the DC voltage set value Ederf to determine the deviation. Input to the DC voltage controller 6.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the active power detector 7. The active power detector 7 detects active power from the AC current and the AC voltage, compares the active power with an active power set value PrefA, and inputs the deviation to the active power controller 8.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the reactive power detector 9. The reactive power detector 9 detects the reactive power from the AC current and the AC voltage, compares it with the reactive power set value Qref, and inputs the deviation to the reactive power controller 10.

In the DC voltage controller 6, the active power controller 8 and the reactive power controller 10, the output signals are controlled so that their detected values are equal to the set values. The output of the DC voltage controller 6 and the output of the active power controller 8 are the selection circuit 11
And one of the outputs is selected.

The output of the selection circuit 11 and the output of the reactive power controller 10 are given to the arithmetic circuit 12. The arithmetic circuit 12 calculates the phase angle φ and the control rate Cm of the PWM control signal based on the reactive power output given from the reactive power controller 10 and the active power output given from the selection circuit 11,
It is given to the PWM control circuit 13. The PWM control circuit 13 determines the phase angle φ, the control rate Cm, and the generation timing of the ON pulse and the OFF pulse given to the GTO. Pulse generation circuit 1
At 4, the on-pulse and the off-pulse for each arm of the self-excited AC / DC converter 3 are generated by these signals and given to the self-excited AC / DC converter 3. In this self-excited AC / DC converter 3,
Operation is performed by turning on / off the GTO thyristor of each arm by this pulse. The converter controller 17 'also performs similar control.

By using such a control system,
In the self-excited DC transmission system with the self-excited AC / DC converters 3 and 3 ', the active power set value Pref is maintained while keeping the DC voltage constant.
The operation is performed such that the electric power of the normal converter is exchanged from the side of the forward converter to the side of the inverse converter, and each converter outputs the reactive electric power of the reactive power set value Qref.

On the other hand, the separately-excited DC power transmission system is composed of separately-excited AC / DC converters 19 and 19 and transformer transformers 28 and 28 'and a DC circuit, and is installed in parallel with the self-excited DC power transmission system. Electric power is exchanged between the AC system 1 and the other AC system 1 '.

In this separately excited DC power transmission system, the controller 21 of the separately excited AC / DC converter 19 and the controller 2 of the converter 19 '.
The operation is performed by 1 '. The internal configurations of the control devices 21 and 21 'are the same, and the direct current detector 29 detects the direct current, the direct current voltage detector 30 detects the direct current voltage, and the direct current controller 24 and the direct current voltage controller 25, respectively.
Outputs a control angle that keeps the DC current and DC voltage at constant values.

Further, when the separately-excited AC / DC converter is operating as an inverse converter, the phase advance circuit 22 detects a condition that may cause commutation failure, and the phase advance controller 23 is informed. To give a phase advance command signal 20. The conditions under which the phase is advanced differ depending on the conditions of the AC system to be connected, etc. Generally, when the distortion of the AC voltage becomes large,
When the commutation failure occurs, the phase advance control is performed when a device such as a transformer is turned on in the vicinity.

The outputs of the phase advance controller 23, the DC current controller 24, and the DC voltage controller 25 are given to a selection circuit 26, one signal is selected and given to a pulse generation circuit 27, and separately excited AC / DC conversion. The operation of the container 19 is performed.
Normally, one of the controller 21 of the separately excited AC / DC converter 19 and the controller 21 'of the separately excited AC / DC converter 19' controls the DC voltage and the other controls the DC current. When the advance controller 23 is activated, the selection circuit 2
In step 6, the phase advance control is preferentially selected.

Here, in the first embodiment of the present invention,
The active power set value calculation circuit 18 for determining the set value Pref of the power interchange amount of the self-excited DC transmission system is provided, and the phase advance command signals 20, 20 'of the separately excited AC / DC converter are transmitted to the converter control devices 21, 21'. A signal is also given to the active power set value calculation circuit 18 at the same time as it is given to the phase advance controller 23 therein.

FIG. 2 is a circuit diagram showing an internal configuration example of the active power set value calculation circuit 18. Here, the direction of active power has a value of "+" in the direction from the AC side to the DC side, and the active power of the converter control device 17 'has a value of "-".

In FIG. 2, "0" and "-.DELTA.Pref" are input to the input terminal of the switch circuit 31, and the switch circuit 3
“0” and “ΔPref” are given to the input terminal of 1 ′, and the phase advance command signals 20 and 20 ′ given from the converter control devices 21 and 21 ′ are turned on, respectively. Switch from "0" to "-ΔPre
f "or" ΔPref ". As ΔPref, a fixed value such as 20% of the DC rated power is set. The outputs of the switch circuits 31 and 31 'are added to the adder 3
In steps 2 and 33, the value is added to the steady-state active power setting value Pref, and the resulting value is set to 1 for the converter control device 17.
As the final active power set value via the next delay circuit 35 and the limiter circuit 86, and to the converter control device 17 'through the sign inversion circuit 34, the first delay circuit 35' and the limiter circuit 86 '. give.

The active power set value Pref in the steady state is
It is a fixed value given from the outside by the central power supply command station or the operator of the substation. Limiter circuit 86,
Reference numeral 86 'is for limiting the active power set values PrefA and PrefB so as not to exceed the DC rated power. The maximum limit value and the minimum limit value are set to values of about ± 100% of the rated power.

Next, the operation of the control device for the self-excited AC / DC converter configured as described above will be described.

In the control device having the configuration as shown in FIG. 1, the voltage distortion of the AC system 1 to which the separately excited AC / DC converter 19 is connected to the self-excited AC / DC converter 3 and the separately excited AC / DC converter 19 in the inverse converter operation. When the phase advance control circuit 22 is operated due to the increase of, for example, the separately excited AC / DC converter 19 performs the phase advance control. The control lead angle β of the separately excited AC / DC converter and the DC voltage Ed have a relationship as shown in the equation (1).

Ed = 1.35 · Vac · COSβ + 3 / π · X · Id (1) In the equation (1), Vac is an AC voltage value, X is an inductance of the transformer, and Id is a DC current. . The control advance angle β is usually operated at a value of about 40 °, and the phase advance control is a control for forcibly setting this β to a large value of about 60 °. Since β increases when the phase advance control is applied, the interchange power decreases as the voltage decreases.

On the other hand, in the embodiment of the present invention, the phase advance command signal 20 is also given to the active power set value calculation circuit 18 of the self-excited AC / DC converter, and the signal causes the switch circuit 31 of FIG. The state of "0" is switched to "-ΔPref". Since the other separately excited AC / DC converter operates as a forward converter, the phase advance control does not work. Therefore, the value added by the adders 32 and 33 is not
To Pref-? Pref.

As a result, the active power setting value PrefA given to the converter control unit 17 changes from the normal "Pref" to "Pref".
ref−ΔPref ”, the active power setting value PrefB given to the converter control device 17 is changed from“ −Pref ”to“ −Pref +
ΔPref ”. When the power interchange direction of the self-excited DC transmission system in advance is the same as the power interchange direction of the converter 17 'side to the converter 17 side, that is, the separately excited DC transmission system, the power set value Pref in the steady state is a negative value. , For example, if this is -60% of the DC rated power, PrefA is -6
It changes from 0% to -80%. Therefore, the interchange power of the self-excited DC transmission system including the self-excited AC / DC converters 17 and 17 'is increased by 20% from the previous value.

When the power exchange directions of the separately excited DC power transmission system and the self-excited DC power transmission system are opposite to each other, PrefA, Pre
On the contrary, the absolute value of fB becomes small, and the interchange power of the self-excited DC transmission system is reduced by 20% from the previous value.

When the converter 19 'is an inverse converter in the separately excited DC transmission system, the switch circuit 31' is operated by the phase advance command signal 20 ', and similarly the self-excited DC transmission system and the separately excited DC transmission system. If the direction of power interchange of the transmission system is the same, the absolute value of the power interchange of the self-excited DC transmission system increases,
When the direction of power interchange is opposite, the self-excited DC transmission system operates in a direction in which the absolute value of power interchange decreases.

As described above, according to the configuration shown in FIG. 1, when the phase advance control operates in the separately excited DC power transmission system and the power interchange amount decreases, the self-excited DC power transmission system installed in parallel with the other If power is being exchanged in the same direction as the exciter-type DC transmission system, the amount of power interchange is increased to compensate for the decrease in power in the separately-excited DC transmission system, and the self-excited DC transmission system moves in the opposite direction to the separately-excited DC transmission system. If there is power interchange, the self-excited AC / DC converter is controlled so as to reduce the amount of power interchange.
As a result, it is possible to reduce fluctuations in the power interchange amount of the separately-excited DC power transmission system and the self-excited DC power transmission system, and to suppress fluctuations given to the AC system.

Now, another example of the configuration of the first embodiment of the control apparatus for the self-excited AC / DC converter according to the present invention will be described.

In the active power set value calculation circuit 18 having the configuration described with reference to FIG. 2, a fixed value such as 20% of the rated power is set as the variation ΔPref of the active power set value. Even if a variable active power set value variation ΔPref corresponding to the operating point of the separately excited DC transmission system is used instead, the same effect as described in the configuration example shown in FIG. 2 can be obtained. That is, when the phase advance control is applied in the separately excited DC transmission system, the interchange power also decreases due to the decrease in the DC voltage Ed, but the decreasing rate is obtained by the expression (2), and the value is determined by the flowing DC current Id. different.

ΔP = ΔEd × Id (2) Therefore, in another configuration example of the first embodiment, the active power set value calculation circuit 18 having the configuration shown in FIG. 3 is used. In FIG. 3, Idp is a DC current set value used in the separately excited DC transmission system, and ΔPEdp is a fixed value of about 3.5%. As the values of −ΔPref and ΔPref given to the input terminals of the switch circuits 31 and 31 ′, ΔPE
A value obtained by multiplying dp and Idp and the amplification factor K by the amplifiers 87 and 87 'is used.

As a result, when the interchanged power of the separately excited DC power transmission system is large, the rate of power decrease due to the phase advance control is large, but the change in the effective power compensated by the self-excited DC power transmission system is also large. It is possible to perform compensation in accordance with the interchanged power of the excitation type DC transmission system. In this case, the amplification factor K is obtained when the signal inside the control device is expressed by the separately-excited DC transmission system and the self-excited DC transmission system as a percentage value or a per-unit value based on the rated power of the self. , A value determined in consideration of the ratio of the rated powers of the separately excited DC transmission system and the self-excited DC transmission system. For example, when the rated power of the separately excited DC transmission system is larger than that of the self-excited DC transmission system, K is set to 1 or more. Use a large value. The value of K can also be used to make adjustments such that the power change in the self-excited DC power transmission system is set to be slightly smaller than the power change in the separately excited DC power transmission system so as not to overcompensate.

As described above, by using the active power setting value circuit 18 having the configuration as shown in FIG. 3, in the system in which the self-excited DC transmission system and the separately excited DC transmission system are connected in parallel, When the phase advance control is applied by the inverse converter of the DC transmission system and the interchange power decreases, the interchange power of the self-excited DC transmission system is changed to compensate for the power decrease of the separately excited DC transmission system. It is possible to reduce the change in the interchange power of the DC power transmission system and the self-excited DC power transmission system, and to suppress the fluctuation given to the AC system as in the case of the configurations of FIGS. 1 and 2.

Next, a second embodiment of the control device for the self-excited AC / DC converter according to the present invention will be described.

FIG. 4 is a circuit configuration diagram showing a second embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals.

As shown in FIG. 4, the self-excited AC / DC converter 3 is connected to the AC bus 1 via the converter transformer 2 as in the conventional device.
It is connected to the. A capacitor 4 is connected to the DC end side of the self-excited AC / DC converter 3, one end of which is connected to the DC terminal A and the other end is connected to the DC terminal B. A self-excited AC / DC converter 3'having the same configuration as the self-excited AC / DC converter 3 is connected to the DC terminals A and B, and its AC end side is connected to an AC bus 1'through a converter transformer 2 '. There is.

The self-excited AC / DC converter 3 is a converter controller 17
In addition, the self-excited AC / DC converter 3'is controlled by the converter controller 17 '. One of the self-excited AC / DC converters is forward-converted, and the other is reverse-converted, so that the AC Power interchange is performed between the grids 1 and 1 '.

In the converter control device 17, the DC voltage is detected by the DC voltage detector 5 connected between both terminals of the DC capacitor 4, and this DC voltage and the DC voltage set value Edref are set.
And the deviation is input to the DC voltage controller 6.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the active power detector 7. The active power detector 7 detects active power from the AC current and the AC voltage, compares the active power with an active power set value PrefA, and inputs the deviation to the active power controller 8.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the reactive power detector 9. The reactive power detector 9 detects the reactive power from the AC current and the AC voltage, compares it with the reactive power set value Qref, and inputs the deviation to the reactive power controller 10.

In the DC voltage controller 6, the active power controller 8 and the reactive power controller 10, the output signals are controlled so that the respective detected values and set values become equal. The output of the DC voltage controller 6 and the output of the active power controller 8 are the selection circuit 11
And one of the outputs is selected.

The output of the selection circuit 11 and the output of the reactive power controller 10 are given to the arithmetic circuit 12. The arithmetic circuit 12 calculates the phase angle φ and the control rate Cm of the PWM control signal based on the reactive power output given from the reactive power controller 10 and the active power output given from the selection circuit 11,
It is given to the PWM control circuit 13. The PWM control circuit 13 determines the phase angle φ, the control rate Cm, and the generation timing of the ON pulse and the OFF pulse given to the GTO.

The pulse generating circuit 14 generates on-pulses and off-pulses for each arm of the self-excited AC / DC converter 3 by these signals and gives them to the self-excited AC / DC converter 3. The self-excited AC / DC converter 3 is operated by turning on / off the GTO thyristor of each arm by this pulse. The converter controller 17 'also performs similar control.

By using such a control system,
In the DC power transmission system using the self-excited AC / DC converters 3 and 3 ′, while keeping the DC voltage constant, the power equivalent to the active power setting value Pref is exchanged from the forward converter side to the inverse converter side, and
Each converter is operated so as to output the reactive power in accordance with the reactive power set value Qref.

On the other hand, the separately-excited DC transmission system is composed of separately-excited AC / DC converters 19 and 19 ', transformers 28 and 28' for converters, and a DC circuit, and is installed in parallel with the self-excited DC transmission system. Electric power is exchanged between the AC system 1 and the other AC system 1 '.

Here, in the second embodiment of the present invention,
Active power set value calculating circuit 18 for determining the set value Pref of the power interchange amount of the self-excited DC transmission system, and active power detectors 37, 37 for detecting the interchange power of the separately excited DC transmission system.
′ Is provided, and the active power detection values PL, PL ′ detected by these active power detectors 37, 37 ′ and the set value Prex of the interchange power that combines the self-excited DC transmission system and the separately excited DC transmission system are used as the active power. It is given to the set value calculation circuit 18.

FIG. 5 is a circuit diagram showing an internal configuration example of the active power set value calculation circuit 18. Here, the direction of active power is "+" in the direction from the AC side to the DC side in both the self-excited AC / DC converter and the separately excited AC / DC converter.

As shown in FIG. 5, the adder 39 sets an interchange power setting value Prefx in which the self-excited DC transmission system and the separately excited DC transmission system are combined and the active power detection value PL of the separately excited AC / DC converter 19.
Of the active power set value Pre for the converter control device 17 via the first-order delay circuit 40 and the limiter circuit 41.
Output as fA. Also, the total interchangeable power setting value P
The sign of the refx is inverted by the sign inversion circuit 38, and the adder 39
′ Is used to determine the difference from the active power detection value PL ′ of the separately excited AC / DC converter 19 ′, and the primary delay circuit 40 ′ and the limiter circuit 4 are used.
It is output as an active power setting value PrefB for the converter control device 17 'via 1'.

The above PL and PL 'have substantially equal values with opposite signs, and the absolute value is large on the side operating in the forward converter due to the loss of the DC circuit or the converter. For example, if the separately excited AC / DC converter 19 side is in the forward converter operation, P
The values are L = 80% and PL ′ = − 78%.

Here, if Prefx = 150%, the active power set value PrefA given to the self-excited AC / DC converter 3 side is 70%, and the active power set value PrefB given to the self-excited AC / DC converter 3'side is It becomes -72%. These values are provided to the converter controllers 17 and 17 '.

In the selection circuits 11 in the converter control devices 17 and 17 ', the output of the DC voltage controller 6 is selected on the one converter side and the output of the DC voltage controller 8 is selected on the other converter side. To do. For example, if the output of the active power control unit 8 is selected on the side of the self-excited AC / DC converter 3 ′, that is, the converter control device 17 ′, the self-excited DC transmission system is effective on the side of the self-excited AC / DC converter 3 ′. The electric power is controlled to -78%, that is, a value of 78% in the inverse converter operation, and the self-excited AC / DC converter 3 side is operated so as to keep the DC voltage constant.

The total interchangeable power set value Prefx of the separately-excited DC transmission system and the self-excited DC transmission system is the central power supply command station or
It is a constant value given from the outside by the operator of the substation. The limiter circuits 41 and 41 'are for limiting the active power set values PrefA and PrefB so as not to exceed the rated power of the self-excited DC transmission system.
A value of about ± 100% of the rated power is set as the minimum limit value.

Next, the operation of the control device for the self-excited AC / DC converter configured as described above will be described.

When the control device having the configuration shown in FIGS. 4 and 5 is used, for example, the AC voltage drops in the separately excited DC transmission system while both the separately excited DC transmission system and the self-excited DC transmission system are operating. If the output of the control system is subject to a limiter due to, or the interchange power decreases due to commutation failure of the inverse converter or phase advance control, the active power detection value PL decreases and the total interchange power setting value Prefx And the difference between PL and PL becomes large, and the active power setting value P for the self-excited DC transmission system is increased.
RefA becomes large and the interchange power of the self-excited DC transmission system increases within a range not exceeding the rating, and the interchange power of the separately excited DC transmission system and the self-excited DC transmission system is maintained at Prefx and operated.

In general, the self-excited AC / DC converter can operate without depending on the voltage of the connected AC system, so that it is more stable and operates faster than the separately excited AC / DC converter. Therefore,
Even if the separately excited AC / DC converter cannot maintain the previous operating state due to the fluctuation of the AC system, the self-excited AC / DC converter is likely to operate by compensating for it. On the other hand, it can respond at high speed.

As described above, according to the configurations shown in FIGS. 4 and 5, when the power interchange amount of the separately excited DC power transmission system decreases, the power interchange amount of the self-excited DC power transmission system installed in parallel with it. Is controlled so that the power interchange amount of the separately excited DC power transmission system and the self-excited DC power transmission system becomes equal to the set value Prefx. As a result, it is possible to reduce the fluctuation amount of the power interchange amount of the separately-excited DC transmission system and the self-excited DC transmission system, and to suppress the fluctuation given to the AC system.

Now, another example of the configuration of the second embodiment of the control device for the self-excited AC / DC converter according to the present invention will be described.

In the active power set value calculation circuit 18 having the configuration described with reference to FIG. 5, the active power set values PrefA and PrefB given to the self-excited AC / DC converter control device are detected as the operating powers of the separately excited AC / DC converters 19 and 19 ', respectively. It was calculated individually from the values PL and PL '.

In the configuration example of the active power set value calculation circuit 18 shown in FIG. 6, the difference between Prefx and PL and the difference between Prefx and PL.
The difference of ′ is given to the average value calculation circuit 42 to be averaged, and the resulting value is used as the primary delay circuit 40 and the limiter circuit 4
1 through the self-excited AC / DC converter 3 active power setting value Pre
It is given to the control device 17 as fA. On the other hand, the value obtained by inverting the sign of the PrefA signal by the sign inverting circuit 43 is given to the converter control device 17 'as the active power set value PrefB on the side of the self-exciting AC / DC converter 3'. For example, Prefx = 150%, PL = 80
%, PL ′ = − 78%, the output of the average value calculation circuit 42 becomes 71%, PrefA = 71%, PrefB = −71.
The value% is given to the converter controller.

As described above, by using the active power set value circuit 18 having the structure shown in FIG.
As in the case of the circuit configuration shown in Fig. 2, when the power interchange amount of the separately excited DC transmission system decreases, the power interchange amount of the self-excited DC transmission system installed in parallel with it increases, and conversely, the separately excited DC transmission system When the power interchange amount of the system increases, the power interchange amount of the self-excited DC transmission system connected in parallel with it decreases, and the total power interchange amount of the separately excited DC transmission system and the self-excited DC transmission system decreases. The set value Prex is controlled. As a result, fluctuations in the power interchange amount of the separately excited DC power transmission system and the self-excited DC power transmission system can be reduced, and fluctuations given to the AC system can be suppressed.

Next, still another configuration example of the second embodiment of the control apparatus for the self-excited AC / DC converter according to the present invention will be described.

In the configuration example of the active power set value circuit 18 described with reference to FIGS. 4 and 5 and the configuration example of the active power set value circuit 18 described with reference to FIG. 6, the active power is supplied to the AC circuits at both ends of the separately excited DC transmission system. PL and PL 'are detected, and the active power set values PrefA and PrefB to be given to the self-excited AC / DC converter are calculated from the values and the total interchange power set value Prefx, but this is also configured as follows. Good.

That is, instead of detecting the active power on the AC side of the separately excited AC / DC converter, the active power PD flowing in the DC circuit of the separately excited DC transmission system is changed from the converter 19 side to the 19 ′ side in the “+” direction. Detected and total flexible power set value Prefx
And the difference is given as PrefA to the controller 17 of the self-excited AC / DC converter 3. Further, the value obtained by inverting the sign is used as PrefB, and the control device 17 for the self-excited AC / DC converter 3'is provided.
Give to ´.

The active power set value circuit 18 having such a configuration
If the power interchange amount of the separately excited DC transmission system decreases even if the above-mentioned configuration example is used, the power interchange amount of the self-excited DC transmission system installed in parallel with it decreases and the separately excited DC transmission system The electric power interchange amount of the transmission system and the self-excited DC transmission system is controlled so as to be the set value refx. As a result, it is possible to reduce fluctuations in the power interchange amount of the separately-excited DC power transmission system and the self-excited DC power transmission system, and to suppress fluctuations given to the AC system.

Next, a third embodiment of the control apparatus for the self-excited AC / DC converter according to the present invention will be described.

FIG. 7 is a circuit configuration diagram showing a third embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals.

As shown in FIG. 7, the self-excited AC / DC converter 3 is connected to the AC bus 1 via the converter transformer 2 as in the conventional device.
It is connected to the. A capacitor 4 is connected to the DC end side of the self-excited AC / DC converter 3, one end of which is connected to the DC terminal A and the other end is connected to the DC terminal B. A self-excited AC / DC converter 3'having the same configuration as the self-excited AC / DC converter 3 is connected to the DC terminals A and B, and its AC end side is connected to an AC bus 1'through a converter transformer 2 '. There is.

The self-excited AC / DC converter 3 includes a converter controller 17
And the self-excited AC / DC converter 3'is controlled by the converter controller 17 '. One of the self-excited AC / DC converters performs forward conversion and the other performs reverse conversion operation, so that AC Power interchange is performed between the grids 1 and 1 '.

In the converter control device 17, the DC voltage is detected by the DC voltage detector 5 connected between both terminals of the DC capacitor 4, and this DC voltage and the DC voltage set value Edref are set.
And the deviation is input to the DC voltage controller 6.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the active power detector 7. The active power detector 7 detects active power from the AC current and the AC voltage, compares the active power with an active power set value PrefA, and inputs the deviation to the active power controller 8.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the reactive power detector 9. The reactive power detector 9 detects the reactive power from the AC current and the AC voltage, compares it with the reactive power set value Qref, and inputs the deviation to the reactive power controller 10.

The DC voltage controller 6, the active power controller 8, and the reactive power controller 10 control the output signals so that their detected values and set values are equal. The output of the DC voltage controller 6 and the output of the active power controller 8 are the selection circuit 11
And one of the outputs is selected.

The output of the selection circuit 11 and the output of the reactive power controller 10 are given to the arithmetic circuit 12. The arithmetic circuit 12 calculates the phase angle φ and the control rate Cm of the PWM control signal based on the reactive power output given from the reactive power controller 10 and the active power output given from the selection circuit 11,
It is given to the PWM control circuit 13. The PWM control circuit 13 determines the phase angle φ, the control rate Cm, and the generation timing of the ON pulse and the OFF pulse given to the GTO. Pulse generation circuit 1
At 4, the on-pulse and the off-pulse for each arm of the self-excited AC / DC converter 3 are generated by these signals and given to the converter 3. The self-excited AC / DC converter 3 is operated by turning on / off the GTO thyristor of each arm by this pulse. The converter controller 17 'also performs similar control.

By using such a control system,
In the DC transmission system with the self-excited AC / DC converters 3 and 3 ', while keeping the DC voltage constant, the power equivalent to the active power setting value Pref is transferred from the forward converter side to the inverse converter side, and each converter The operation is performed so as to output the reactive power according to the reactive power set value Qref.

On the other hand, the separately-excited DC transmission system is composed of the separately-excited AC / DC converters 19 and 19 'and transformer transformers 28 and 28' and a DC circuit, and is installed in parallel with the self-excited DC transmission system. Electric power is exchanged between the AC system 1 and the other AC system 1 '. The separately excited AC / DC converters 19 and 19 'are operated by the converter control devices 21 and 21', respectively, so that DC power transmission is controlled to the set value Idp and DC voltage is controlled to the set value Edp.

Here, in the third embodiment of the present invention,
The active power set value Prefo externally given to the self-excited DC transmission system, such as the operator of the central power supply command station or the substation, or the higher-level control device, is set to different time constants T1, T2, T.
It is input to a plurality of first-order delay circuits 44 having 3 and the output signal thereof is given to the switch circuit 45. The switch circuit 45 selects which of the outputs of the plurality of first-order delay circuits 44 is selected according to the value of the DC current setting value Idp of the separately excited DC power transmission system. Then, the values selected by the switch circuit 45 are given to the converter control devices 17 and 17 'as final active power set values PrefA and PrefB.

For example, the time constant of the primary delay circuit 44 is set to T1.
>T2> T3, and in the switch circuit 45, Idp>
The output of the first-order lag circuit of T2 is selected at 50%, and the output of the first-order lag circuit of T3 is selected in other cases.

Next, the operation of the control device for the self-excited AC / DC converter configured as described above will be described.

In the control device having the configuration as shown in FIG. 7, when the separately excited DC power transmission system operates at a large value of 80% or more DC current, the active power set value PrefA of the self-excited DC power transmission system, PrefB becomes a value through a first-order lag circuit with a large time constant T1 with respect to the active power setting value Prefo given from the outside, and even if the value of Prefo is changed while operating in this state, the values of PrefA and PrefB The change is gradual, and the power interchange amount of the self-excited DC transmission system is changed slowly.

On the contrary, the separately excited DC power transmission system has a DC current of 50%.
When operating or stopping at the following small values, active power setpoints PrefA, P of the self-excited DC transmission system
refB becomes a value through a first-order lag circuit with a small time constant T3 with respect to the active power setting value Prefo given from the outside, and if the value of Prefo is changed while operating in this state, Pre
Since the values of fA and PrefB also change rapidly, the power interchange amount of the self-excited DC transmission system is changed rapidly. When the DC current of the separately excited DC transmission system is 50% or more and 80% or less, the power interchange amount is changed at an intermediate speed.

As described above, according to the control device for the self-excited AC / DC converter having the configuration shown in FIG. 7, when the power interchange amount of the separately excited DC power transmission system is large, the change in the power interchange amount of the self-excited DC power system is performed. Is performed slowly, and when the power exchange amount of the separately-excited DC power system is small or stopped, the change of the power interchange amount of the self-excited DC transmission system is performed at high speed.

The self-excited DC power transmission system is characterized in that it can control active power and reactive power at high speed.
When a load is cut off or a power source is dropped in the AC system, the high-speed control of the interchange power that makes use of the characteristics can be changed to stabilize the entire power system. However, when a separately excited inverse converter is operating near the self-excited DC transmission system, if the self-excited AC / DC converter changes active power or reactive power too quickly, the resulting AC system The commutation failure may occur due to the fluctuation of.

The commutation failure of the separately-excited inverse converter is more likely to occur as the DC current and the DC voltage are operating at a large value, but in the case of the separately-excited DC transmission system, the DC voltage is usually , It is operated at 100% of the rating, and the power interchange amount is adjusted by changing the value of DC power transmission. Therefore, it can be said that the ease of commutation failure depends on the magnitude of the direct current.

According to the control device for the self-excited AC / DC converter having the configuration shown in FIG. 7, when the separately excited AC / DC converter is operated in a state of a large DC current that is likely to cause commutation failure, the self-excited DC / DC converter system Change the power slowly to prevent commutation failure, and change the power of the self-excited DC transmission system at high speed when the separately excited AC / DC converter is in a small DC current state where it is hard to fail commutation or is stopped. It is possible to effectively stabilize the entire system in the event of a load cutoff or power loss.

Now, another example of the configuration of the third embodiment of the control device for the self-excited AC / DC converter according to the present invention will be described.

In the active power set value calculation circuit 18 having the configuration described with reference to FIG. 7, the rate of change of the active power set values PrefA and PrefB given to the self-excited AC / DC converter control device is determined by the current set value Idp of the separately excited DC transmission system. I was trying to switch by.

In the configuration example shown in FIG. 8, not only the active power set value Pref of the self-excited DC power transmission system but also the reactive power set value Qref of the externally applied set value Qre is similarly set.
fAo and QrefBo are multiple 1s with different time constants.
It is input to the next-delay circuits 46 and 46 ', and its output is switched by the switch circuits 47 and 47'. This switch circuit 47,
Reference numeral 47 'is for switching by the output of the condition selection circuits 49, 49'.

Here, the condition selection circuits 49, 49 'are constructed as shown in FIG. That is, as shown in FIG. 9, the level detectors 51, 52, the NOT circuit 53, A
ND circuits 54 and 55 and an OR circuit 56,
The separately set DC / DC converter system current input value Idp and the power flow direction command signal REC / INV are input, and the separately excited AC / DC converter 1
When 9 is REC, that is, when the forward converter is operating, when the level detector 51 detects that Idp is larger than Id1, the output is "1", and when the separately excited AC / DC converter 19 is INV, that is, when the inverse converter is operating. Is detected by the level detector 52.
When it is detected that it is larger than d2, the output operates to become "1".

When the output of the condition selecting circuit 49 is "1", the switch circuit 47 selects the terminal t1 and operates so that the output of the circuit having the time constant T4 in the first-order delay circuit 46 is selected.

Here, the active power needs to be commonly controlled by the converters at both ends of the DC power transmission system, but the reactive power can be controlled independently by each converter, so that separate outputs for the QrefA and QrefB outputs are provided. First-order delay circuits 46 and 46 ', switch circuits 47 and 47', and condition selection circuits 49 and 49 'are provided.

As described above, according to the control device for the self-excited AC / DC converter having the configuration as shown in FIG. 8, the separately excited AC / DC converter is operated by the inverse converter in a state of a large DC current which is likely to cause commutation failure. Occasionally, when changing the power of the self-excited DC power transmission system and the reactive power slowly to prevent commutation failure, and when the separately excited AC / DC converter is in a small DC current state where it is difficult for commutation failure or is stopped. Alternatively, when the forward converter is operating, the power of the self-excited DC transmission system and the reactive power can be changed at high speed to effectively stabilize the entire system in the event of load interruption or power loss. .

Further, in the configuration shown in FIGS. 7 and 8 of the third embodiment, the changing speed of the active power set value is switched only by the current set value Idp of the separately excited DC transmission system. The same effect can be obtained even if switching is performed under the conditions of both the power flow direction and the power flow direction of the separately excited DC power transmission system.

That is, the characteristics of the AC system 1 and the AC system 1'to which the separately excited DC power transmission system or the self-excited DC power transmission system is connected are different. In the case of a system where the short-circuit capacity is small on the 1st side and is easily shaken, commutation failure is less likely to occur even if the separately excited AC / DC converter 19 connected to the system 1 is operating as an inverse converter. The operating point can be changed at high speed, but if the separately excited AC / DC converter 19 ′ connected to the system 1 ′ with the reverse flow direction is operating as an inverse converter, commutation tends to fail, so self-excited DC It is necessary to slowly operate the operating point of the power transmission system.

Therefore, under the condition that the separately excited alternating-current / direct-current converter 19 'is an inverse converter and Idp is large, 1 having a large time constant is used.
Even if a condition is selected such that the output of the next delay circuit is selected, the above-described respective configuration examples and the effect of shaking can be obtained.

Next, a fourth embodiment of the control apparatus for the self-excited AC / DC converter according to the present invention will be described.

FIG. 10 is a circuit configuration diagram showing a fourth embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals.

As shown in FIG. 10, a self-excited AC / DC converter 3 is connected to an AC busbar 1 via a converter transformer 2 as in the conventional device. A capacitor 4 is connected to the DC end side of the self-excited AC / DC converter 3, one end of which is connected to the DC terminal A.
, And the other end is connected to the DC terminal B. These DC terminals A and B are connected to other self-excited AC / DC converters in the case of a DC transmission system, DC power supplies in the case of an inverter device, and open in the case of a static var compensator. Has become.

The self-excited AC / DC converter 3 includes a converter controller 17
Is controlled by In this converter control device 17, a DC voltage detector 5 connected between both terminals of the DC capacitor 4 is used.
The DC voltage is detected by means of this, the DC voltage is compared with the DC voltage set value Edref, and the deviation is input to the DC voltage controller 6.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the active power detector 7. The active power detector 7 detects active power from the AC current and the AC voltage, compares the active power with an active power set value PrefA, and inputs the deviation to the active power controller 8.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the reactive power detector 9. The reactive power detector 9 detects the reactive power from the AC current and the AC voltage, compares it with the reactive power set value Qref, and inputs the deviation to the reactive power controller 10.

In the DC voltage controller 6, the active power controller 8 and the reactive power controller 10, the output signals are controlled so that the respective detected values and set values become equal. The output of the DC voltage controller 6 and the output of the active power controller 8 are given to the selection circuit 11, and either output is selected.

The output of the selection circuit 11 and the output of the reactive power controller 10 are given to the arithmetic circuit 12. The arithmetic circuit 12 calculates the phase angle φ and the control rate Cm of the PWM control signal based on the reactive power output given from the reactive power controller 10 and the active power output given from the selection circuit 11,
It is given to the PWM control circuit 13. The PWM control circuit 13 determines the phase angle φ, the control rate Cm, and the generation timing of the ON pulse and the OFF pulse given to the GTO. Pulse generation circuit 1
At 4, the on-pulse and the off-pulse for each arm of the self-excited AC / DC converter 3 are generated by these signals and given to the converter 3. The self-excited AC / DC converter 3 is operated by turning on / off the GTO thyristor of each arm by this pulse.

By using such a control system,
While keeping the DC voltage constant, the operation is performed so as to accommodate the electric power of the valid set value Pref and output the reactive power of the reactive power set value Qref.

On the other hand, the separately excited AC / DC converter 19 has the same AC system 1 as the self-excited AC / DC converter 3 via the conversion / induction transformer 28.
Connected to. The separately excited AC / DC converter 19 is used in the control device 2
1, the DC current is controlled to operate at the set value Idp and the DC voltage is controlled to operate at the set value Edp.

When the separately-excited AC / DC converter 19 is operating as an inverse converter, the phase advance command circuit 22 gives the phase advance command signal 20 to the phase advance control circuit 23 when voltage distortion occurs in the AC system. As a result, control for forcibly increasing the control advance angle β is performed.

Here, in the fourth embodiment of the present invention,
The phase advance signal 20 of the separately excited AC / DC converter is supplied to the switch circuit 5
7 control signal. As the input signal of the switch circuit 57, the variation ΔQref of the reactive power setting value is input, and the switch is turned on when the phase advance signal 20 is turned “on”. This output is added by the adder 57 to the normal reactive power setting value Qref and is given to the reactive power controller 10 in the converter control device 17 as a final reactive power setting value.

In this case, the amount of change in reactive power set value ΔQref
Is a value of “+”, that is, a value in the direction of increasing the reactive power output.

Next, the operation of the control device for the self-excited AC / DC converter configured as described above will be described.

In the control device having the configuration as shown in FIG. 10, when the separately excited AC / DC converter 19 is operating as the inverse converter, the phase advance command circuit 22 causes the phase advance command circuit 22 to increase due to a large voltage distortion of the AC system 1. When it operates, the phase advance control circuit 23 operates in the separately excited inverse converter 19 by the command signal. The phase advance control circuit 23 forcibly controls the control advance angle β from a steady value of about 40 ° to a large value of about 60 °, but the value of the reactive power consumed by the separately excited AC / DC converter. Q is generally expressed by the following equation: Q = Id.Edo. (1-cos ² β) ^1/2 (3), so that when the phase advance control circuit 23 operates, the reactive power consumption by the separately excited AC / DC converter is increased. The amount increases.

In the equation (3), Id is a DC current, Edo is a no-load DC voltage, which is a value determined by the AC system voltage.

On the other hand, when the phase advance command circuit 22 outputs the phase advance signal 20, the switch circuit 57 is turned on.
The reactive power setting value given to the converter control device 17 changes from Qref in the steady state to Qref + ΔQref.

Since ΔQref is a value of "+", the operating point of the self-excited AC / DC converter 3 changes so as to increase the reactive power output or decrease the reactive power consumption.

As described above, according to the control device for the self-excited AC / DC converter having the structure as shown in FIG.
While the phase advance control is applied to increase the reactive power consumption, the self-excited AC / DC converter 3 operates to increase the reactive power output or decrease the reactive power consumption.

The reason why the phase advance control is applied in the separately excited AC / DC converter is to prevent commutation failure. However, when the configuration shown in FIG. 10 is not applied, the phase advance control is applied and the reactive power consumption increases. Causes the AC voltage to decrease, which causes the effect of phase advance control to be halved in terms of commutation failure. However, if the configuration shown in FIG. 10 is used, the reactive power output of the self-excited AC / DC converter increases, so that the AC voltage is prevented from decreasing, the AC voltage fluctuation is reduced, and the commutation failure of the separately excited inverse converter occurs. The prevention effect can be enhanced.

Here, another configuration example of the fourth embodiment of the control apparatus for the self-excited AC / DC converter according to the present invention will be described.

In the controller having the configuration shown in FIG. 10, the phase advance control is applied by the separately excited inverse converter, so that the reactive power output of the self-excited AC / DC converter is controlled to be large, but the phase control is applied. It is also possible to increase the reactive power output of the self-excited AC / DC converter and operate so as to increase the AC voltage to prevent commutation failure of the separately excited inverse converter.

That is, the operating state signal 50 of the separately excited alternating-current / direct-current converter 19 shown in FIG. 11 is supplied to the converter control device 21 and is also supplied to the AND circuit 63 via the NOT circuit 62. When the state signal is "1" during the operation of the forward converter and "0" during the operation of the inverse converter, the signal input to the AND circuit 63 is "1" during the operation of the inverse converter.

On the other hand, the distortion detection circuit 59 causes the AC system 1
When the voltage distortion is detected and becomes a certain value or more, a signal of "1" is given to the AND circuit 63 via the ON delay circuit 60 and the OFF delay circuit 61.

As a result, the main cause of commutation failure in the separately excited AC / DC converter is the distortion of the AC voltage or the decrease of the AC voltage. According to the control device having the configuration shown in FIG. There is a possibility of commutation failure due to large voltage distortion. However, in such a case, by increasing the reactive power output of the self-excited AC / DC converter and raising the AC voltage,
The commutation failure of the separately excited inverse converter can be prevented. If the phase advance control of the separately excited AC / DC converter is performed in that state,
As in the configuration example shown in FIG. 0, it is possible to prevent the AC voltage from decreasing and enhance the effect of preventing commutation failure.

Next, another configuration example of the fourth embodiment of the control apparatus for the self-excited AC / DC converter according to the present invention will be described.

In the configurations shown in FIGS. 10 and 11, since the operation is performed to increase the AC voltage, the switch circuit 57 is operated to increase the reactive power setting value of the self-excited AC / DC converter. Alternatively, the reactive power output can be increased by performing AC voltage control and increasing the AC voltage set value. In this case, the condition signal is
0, similarly to the configuration example of FIG. 11, the change amount ΔVref of the AC voltage set value is given to the switch circuit 57 and added to the AC voltage set value Vref in the steady state.

Even with such a configuration, commutation failure of the separately excited type AC / DC converter can be prevented, fluctuations in AC voltage can be suppressed to a small level, and the same effect as in the configurations of FIGS. 10 and 11 can be obtained. it can.

Next, a fifth embodiment of the control apparatus for the self-excited AC / DC converter according to the present invention will be described.

FIG. 12 is a circuit configuration diagram showing a fifth embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals.

As shown in FIG. 12, a self-excited AC / DC converter 3 is connected to an AC busbar 1 via a converter transformer 2 as in the conventional device. A capacitor 4 is connected to the DC end side of the self-excited AC / DC converter 3, one end of which is connected to the DC terminal A.
, And the other end is connected to the DC terminal B. These DC terminals A and B are connected to other self-excited AC / DC converters in the case of a DC transmission system, DC power supplies in the case of an inverter device, and open in the case of a static var compensator. Has become.

The self-excited AC / DC converter 3 includes a converter controller 17
Is controlled by In this converter control device 17, a DC voltage detector 5 connected between both terminals of the DC capacitor 4 is used.
The DC voltage is detected by means of this, the DC voltage is compared with the DC voltage set value Edref, and the deviation is input to the DC voltage controller 6.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the active power detector 7. The active power detector 7 detects active power from the AC current and the AC voltage, compares the active power with an active power set value PrefA, and inputs the deviation to the active power controller 8.

Further, the system voltage input via the transformer PT is input to the AC voltage detector 15. The AC voltage detector 15 detects an AC voltage, compares it with an AC voltage set value Vref, and inputs the deviation to the AC voltage controller 16.

The DC voltage controller 6, the active power controller 8, and the AC voltage controller 16 control the output signals so that their detected values and set values are equal.

The output of the DC voltage controller 6 and the output of the active power controller 8 are given to the selection circuit 11, and either output is selected. Further, the output signal of the AC voltage controller 16 is given to the limiter circuit 68.

Output of the selection circuit 11 and limiter circuit 6
The output of 8 is given to the arithmetic circuit 12. This arithmetic circuit 1
2 calculates the phase angle φ and the control rate Cm of the PWM control signal based on the output of the selection circuit 11 and the output of the limiter circuit 68, and gives them to the PWM control circuit 13. PWM control circuit 13
Then, the phase angle φ, the control rate Cm, and the generation timing of the ON pulse and the OFF pulse given to the GTO are determined. The pulse generation circuit 14 generates on-pulses and off-pulses for each arm of the self-excited AC / DC converter 3 by these signals and gives them to the converter 3. The converter 3 is operated by turning on / off the GTO thyristor of each arm by this pulse.

By using such a control system,
While keeping the DC voltage constant, the operation is performed so that the electric power of the valid set value Pref is exchanged and the reactive power is output so that the voltage of the AC system becomes equal to the set value Vref.

On the other hand, the separately excited AC / DC converter 19 has the same AC system 1 as the self-excited AC / DC converter 3 via the conversion / induction transformer 28.
Connected to. The separately excited AC / DC converter 19 is used in the control device 2
It is operated under the control of 1.

Further, a power capacitor 65 is connected to the AC system 1 via a circuit breaker 64.

Here, in the fifth embodiment of the present invention,
The closing command 66 for the circuit breaker 64 is given to the circuit breaker and also to the limit value control circuit 67. on the other hand,
The operating state signal 50 of the separately excited AC / DC converter 19 is input to the limit value control circuit 67 via the NOT circuit 62. Since the operating state signal is "1" at the time of the forward converter and "0" at the time of the inverse converter, the signal given to the limit value control circuit 67 becomes "1" at the time of the inverse conversion. The output of the limit value control circuit 67 is
It is given to the output limiter circuit 68 of the AC voltage controller in the converter controller 17, and controls the limit value of the limiter circuit 68.

The internal structure of the limit value control circuit 67 is shown in FIG.
3 shows the time sequence of each signal in FIG. 13 in FIG. In the limit value control circuit 67, the circuit breaker closing command 66 and the signal indicating that the separately excited AC / DC converter is operating as an inverse converter are ANDed, and a one-shot signal is generated when the signal turns from OFF to ON. It is applied to the one-shot signal generating circuit 70. Further, this signal is given to the first-order delay circuits 72 and 73 via the off-delay circuit 71.

The first-order delay circuits 72 and 73 are respectively provided when the output of the off-delay circuit 71 changes from off to on.
In the circuit that operates from on to off, the outputs are added by the adder 74, and the change in the minimum limit value ΔQmi
The value of n is multiplied by the multiplier 75, and the output is added to the steady-state minimum limit value ΔQmin ′ and output. FIG. 14 shows how each signal in FIG. 13 operates when the output (A) of the AND circuit 69 is turned on / off.

The value obtained as a result is used as the minimum limit value of the limiter circuit 68 of FIG. here,
The value of the reactive power Q is "+" in the forward direction in which the reactive power is output, and "-" is in the delay direction in which the reactive power is consumed.
The minimum limit value Qmin 'in the steady state is set to -100% of the reactive power rating of the converter, and the variation ΔQmin is set to a value such as 80%.

Next, the operation of the control device for the self-excited AC / DC converter configured as described above will be described.

In the control device having the configuration as shown in FIG. 12, when the separately excited AC / DC converter 19 is operating as the inverse converter, when the power condenser 65 is turned on by the circuit breaker 64, the turn-on command is turned on. As a result, the minimum limit value Qmin of the output limiter 68 of the AC voltage controller of the self-excited AC / DC converter changes from -100% in the steady state to -20%. Since the AC voltage rises when the capacitor is turned on in this state, the AC voltage controller 1 of the self-excited AC / DC converter 1
6 operates in the negative direction so as to reduce the voltage.

However, since the output limit value is -20%, the value cannot be smaller than that. During the delay time set by the off-delay circuit 71, the minimum limit value is -20%, and then returns to -100% according to the time constant T2 of the first-order delay circuit 73. The AC voltage is still rising due to the capacitor, but the minimum limit value Qmin of the voltage controller of the self-excited AC / DC converter moves in the negative direction, so the reactive power consumption of the self-excited AC / DC converter is reduced. Operates in the direction of increasing and decreasing the AC voltage.

According to the fifth embodiment having the structure as shown in FIGS. 12 and 13, the separately excited AC / DC converter 1 is used.
When the inverse converter is operating in 9 and a capacitor is turned on in the vicinity, even if the AC voltage rises due to the turning on of the capacitor, the self-excited AC / DC converter 3 lowers the AC voltage for a while after the capacitor is turned on. Does not operate, and after a certain period of time, the reactive power consumption is controlled to increase so that the value becomes equal to the set value Vref.

When the capacitor is put into the system, the AC voltage rises, while the AC voltage is distorted. Therefore, commutation failure may occur if there is a separately excited inverse converter nearby. If the AC voltage control by the self-excited AC / DC converter is performed without adopting the configuration shown in FIG. 12, the self-excited AC / DC converter operates so as to reduce the increased AC voltage due to the insertion of the capacitor, so that commutation failure easily occurs. But, Figure 1
With the configuration shown in FIG. 2, the self-excited AC / DC converter hardly operates in the direction of lowering the AC voltage, so that the possibility of commutation failure can be reduced. Also, since the distortion due to the insertion of the capacitor disappears from several tens of milliseconds to several hundreds of seconds,
Thereafter, the limiter for AC voltage control of the self-excited AC / DC converter is widened to operate at the maximum rated value, so that the AC voltage can be lowered to a set value for operation.

With the configuration shown in FIG. 12 as described above,
It is possible to prevent commutation failure due to the insertion of a capacitor, and to control the AC voltage to return to a value that is equal to the set value after a certain period of time.

Here, another configuration example of the fifth embodiment of the control device for the self-excited AC / DC converter according to the present invention will be described.

In the controller having the configuration shown in FIG. 15, the closing command signal 66 for the circuit breaker 64 and the separately excited AC / DC converter 19 are connected.
The output signal of the NOT circuit 62 indicating whether or not is the inverse converter operation is given to the voltage setting value calculation circuit 77. When the voltage setting value calculation circuit 77 is in a steady state, that is, when the logical product of the circuit breaker closing command signal 66 and the output of the NOT circuit 62 is "0", the voltage setting value calculation circuit 77 outputs a constant voltage setting value Vref given from the outside and self-exciting type. When the separately excited AC / DC converter 19 is operating as an inverse converter and the breaker closing command signal 66 operates, the voltage setting value is changed to a higher value for a certain period of time. It operates so as to return to the original Vref later.

With the control device having such a configuration, the AC voltage is constant when the separately-excited AC / DC converter adjacent to the self-excited AC / DC converter 3 is in the inverse converter operation and the capacitor is turned on in the vicinity. Outputs reactive power that is higher than usual. As a result, it is possible to prevent the commutation failure of the separately excited AC / DC converter, and it is possible to obtain the same effect as that of the control device having the configuration shown in FIG.

Next, still another configuration example of the fifth embodiment of the control apparatus for the self-excited AC / DC converter according to the present invention will be described.

In the configuration examples shown in FIGS. 10 and 11, since the operation is performed to increase the AC voltage, the switch circuit 57 is operated to increase the reactive power set value of the self-excited AC / DC converter. Alternatively, reactive power output can be increased by performing AC voltage control and increasing the AC voltage set value. In this case, as the condition signal, the change amount ΔVref of the AC voltage setting value is given to the switch circuit 57 in the same manner as in the configuration examples of FIGS. 10 and 11, and this is added to the steady-state AC voltage setting value Vref.

Even with such a configuration, commutation failure of the separately excited type AC / DC converter can be prevented, fluctuations in AC voltage can be suppressed to a small level, and the same effects as in the configurations of FIGS. 10 and 11 can be obtained. it can.

Next, a sixth embodiment of the control apparatus for the self-excited AC / DC converter according to the present invention will be described.

FIG. 16 is a circuit configuration diagram showing a sixth embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals.

As shown in FIG. 16, a self-excited AC / DC converter 3 is connected to an AC bus 1 via a converter transformer 2 as in the conventional device. A capacitor 4 is connected to the DC end side of the self-excited AC / DC converter 3, one end of which is connected to the DC terminal A.
, And the other end is connected to the DC terminal B. A self-excited AC / DC converter 3'having the same configuration as the self-excited AC / DC converter 3 is connected to the DC terminals A and B, and its AC end side is connected to an AC bus 1'through a converter transformer 2 '. There is.
Here, the case of DC power transmission is shown, but in the case of an inverter device, a DC power source is connected, and in the case of a static var compensator, it is in an open state.

The self-excited AC / DC converter 3 includes a converter controller 17
Is controlled by In this converter control device 17, the DC voltage detector 5 detects the DC voltage, compares it with the DC voltage set value Edref, and inputs the deviation to the DC voltage controller 6.

Further, the AC current detected via the current transformer CT and the AC voltage detected via the transformer PT are input to the active power detector 7. The active power detector 7 detects active power from the AC current and the AC voltage, compares the active power with an active power set value PrefA, and inputs the deviation to the active power controller 8.

Further, the system voltage is input from the AC system 1 through the transformer PT to the AC voltage detector 15, and the AC voltage detected by the AC voltage detector 15 is compared with the AC voltage set value Vref. The deviation is input to the AC voltage controller 16.

The DC voltage controller 6, the active power controller 8, and the AC voltage controller 16 control the output signal so that the detected value and the set value are equal to each other. The output of the DC voltage controller 6 and the output of the active power controller 8 are given to the selection circuit 11, and either output is selected. Further, the output signal of the AC voltage controller 16 is given to the limiter circuit 68.

Output of the selection circuit 11 and limiter circuit 6
The output of 8 is given to the arithmetic circuit 12. This arithmetic circuit 1
2 calculates the phase angle φ and the control rate Cm of the PWM control signal based on the output of the selection circuit 11 and the output of the limiter circuit 68, and gives them to the PWM control circuit 13. PWM control circuit 13
Then, the phase angle φ, the control rate Cm, and the generation timing of the ON pulse and the OFF pulse given to the GTO are determined. The pulse generation circuit 14 generates on-pulses and off-pulses for each arm of the self-excited AC / DC converter 3 by these signals and gives them to the converter 3. The converter 3 is operated by turning on / off the GTO thyristor of each arm by this pulse.

By using such a control system,
While keeping the DC voltage constant, the operation is performed so that the electric power of the valid set value Pref is exchanged and the reactive power is output so that the voltage of the AC system becomes equal to the set value Vref.

Here, in the sixth embodiment of the present invention, the undervoltage relay 78 detects that the voltage of the AC system 1 has dropped below a certain value. This detection level is set to a value of about 50% of the rated voltage, for example. The output of the undervoltage relay 78 is given to the limit value control circuit 79. The output of the limit value control circuit 79 is given to the output limiter 68 of the AC voltage controller 16 of the converter control device to control the maximum limit value of the limit circuit 68.

The internal structure of the limit value control circuit 79 is shown in FIG.
7 shows the time sequence of each signal of FIG. 17 in FIG. In the limit value control circuit 79, the operation signal of the undervoltage relay 78 is input, and this is input via the on-delay circuit 80 and the off-delay circuit 81 to the primary delay circuits 82 and 83.
Give to. The first-order delay circuits 82 and 83 are circuits that operate when the output of the off-delay circuit 81 changes from off to on and from on to off, respectively, and the outputs are added to change the maximum limit value ΔQmax. Adder 8
Multiply by 4 and output the minimum limit value Qma in steady state
Add x to the negative direction and output. FIG. 18 shows how each signal in FIG. 17 operates when the output (A) of the undervoltage relay 78 is turned on / off.

The value obtained as a result is used as the maximum limit value of the limiter circuit 68 of FIG.

Here, the value of the reactive power Q is "+" in the forward direction in which the reactive power is output, and "-" is in the delay direction in which the reactive power is consumed. The maximum limit value Qmax 'in the steady state is given 100% of the reactive power rating of the converter, and the variation ΔQmax is set to a value of 90%, for example.

Next, the operation of the control device for the self-excited AC / DC converter configured as described above will be described.

In the control device having the configuration as shown in FIG. 16, when the ground fault accident or the short-circuit accident occurs in the AC system 1 and the voltage drops significantly, the undervoltage relay 78 operates.

As a result, the operation of the limit value control circuit 79 lowers the maximum limit value Qmax of the output limiter 68 of the AC voltage controller from + 100% in the normal state to + 10%. In the AC voltage controller 16, since the AC voltage is significantly lower than the set value Vref, the reactive power output is changed in the positive direction in order to increase the voltage.

However, since the maximum limit value of the limiter circuit 68 is + 10%, so large reactive power output is not performed. When the AC system fault is eliminated in this state, the AC voltage recovers to a value near the steady value, the output of the undervoltage relay 78 is turned off, and the limit value control circuit 7
When the time set by the off-delay circuit 81 in 9 elapses, the maximum limit value Qmax returns to the original + 100%. As a result, normal AC voltage control is performed.

As described above, the sixth structure having the structure shown in FIG.
According to the embodiment of the present invention, when the AC voltage in the AC system 1 connected to the self-excited AC / DC converter 3 is significantly reduced due to a ground fault or the like, during the accident and for a while after the accident is cleared,
The reactive power output of the self-excited AC / DC converter is limited so as not to become a large value. If this is not done, the voltage will drop during the accident, so the self-exciting AC / DC converter will
Therefore, it tries to increase the AC voltage and outputs the maximum reactive power in the positive direction to operate.

If the accident is eliminated in this state, a large overvoltage is generated, which causes problems such as equipment damage.

By using the circuit having the configuration shown in FIG. 16, since the self-excited AC / DC converter does not output a very large reactive power during an accident and for a certain time after the accident is removed, the occurrence of such overvoltage after the accident is removed is prevented. be able to.

[0203]

As described above, according to the control device for a self-excited AC / DC converter of the present invention, the following effects can be obtained.

(1) In a system in which a self-excited DC transmission system and a separately-excited DC transmission system are installed in parallel, when phase advance control operates in the inverse converter of the separately-excited DC transmission system and the interchange power decreases. , By changing the interchange power of the self-excited DC transmission system so as to compensate for the decrease in power, the fluctuation of the power interchange amount of the separately excited DC transmission system and the self-excited DC transmission system is reduced, and the connected AC It is possible to suppress the upset to the system.

(2) In a system in which a self-excited DC transmission system and a separately excited DC transmission system are installed in parallel, the separately excited system is selected from the set value of the power interchange amount of the separately excited DC transmission system and the self-excited DC transmission system. By giving the value obtained by subtracting the detected value of the power actually exchanged in the DC transmission system as the active power setting value of the self-excited DC transmission system, the power interchange of the separately excited DC transmission system and the self-excited DC transmission system is combined. The amount can be controlled to be constant to reduce the fluctuation, and fluctuations given to the AC system to which the converter is connected can be suppressed.

(3) In a system in which a self-excited DC transmission system and a separately excited DC transmission system are installed adjacent to each other, the effective power converter of the self-excited AC / DC converter is effective according to the operating point of the separately excited AC / DC converter. By changing the changing speed of the power set value or reactive power set value, it is possible to prevent commutation failure of the separately excited AC / DC converter due to the fluctuation of the AC system due to the change of the operating point of the self-excited AC / DC converter. In addition, under operating conditions in which the commutation failure of the separately excited AC / DC converter is small, the operating point of the self-excited AC / DC converter can be changed as fast as possible.

(4) In a system in which a self-excited AC / DC converter for performing constant reactive power control and a separately excited AC / DC converter are installed adjacent to each other, the separately excited AC / DC converter is operating as an inverse converter, and phase advance control is performed. In such a case, by advancing the reactive power set value of the self-excited AC / DC converter and changing it toward the reactive power, it is possible to prevent the AC voltage from decreasing and prevent the commutation failure of the separately excited inverse converter.

(5) When a capacitor is turned on in the vicinity of a system in which a self-excited AC / DC converter for controlling AC voltage and a separately excited AC / DC converter are installed adjacent to each other, the separately excited AC / DC converter performs inverse conversion. In order to prevent the reactive power consumption of the self-excited AC / DC converter from increasing by operating the output limiter of AC voltage control of the self-excited AC / DC converter or operating the AC voltage set value, on the condition that the converter is operating. By controlling and operating so that the value of the AC voltage becomes high, it is possible to prevent commutation failure of the separately excited type AC / DC converter due to the distortion when the capacitor is turned on.

(6) When an accident such as a ground fault or a short circuit occurs in the AC system to which the self-excited AC / DC converter for AC voltage control is connected, the reactive power output of the converter has a large value during the accident and after the accident is eliminated. By controlling so as not to become, it is possible to prevent the AC overvoltage generated after the accident is removed.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a system configuration example of a first embodiment of a control device for a self-excited AC / DC converter according to the present invention.

FIG. 2 is a block diagram showing in detail an internal configuration of an active power setting value calculation circuit according to the same embodiment.

FIG. 3 is a block diagram showing another internal configuration of the active power setting value calculation circuit according to the same embodiment.

FIG. 4 is a circuit diagram showing a system configuration example of a second embodiment of a control device for a self-excited AC / DC converter according to the present invention.

FIG. 5 is a block diagram showing in detail an internal configuration of an active power setting value calculation circuit according to the same embodiment.

FIG. 6 is a block diagram showing another internal configuration of the active power setting value calculation circuit according to the same embodiment.

FIG. 7 is a circuit diagram showing a system configuration example of a third embodiment of a control device for a self-excited AC / DC converter according to the present invention.

FIG. 8 is a circuit diagram showing another system configuration example of the same embodiment.

9 is a block diagram showing the internal configuration of the condition selection circuit shown in FIG.

FIG. 10 is a circuit diagram showing a system configuration example of a fourth embodiment of a control device for a self-excited AC / DC converter according to the present invention.

FIG. 11 is a circuit diagram showing another system configuration example of the same embodiment.

FIG. 12 is a circuit diagram showing a system configuration example of a fifth embodiment of a control device for a self-excited AC / DC converter according to the present invention.

FIG. 13 is a block diagram showing in detail an internal configuration of a limit value control circuit according to the same embodiment.

14 is a time sequence diagram showing how internal signals of the limit value control circuit shown in FIG. 13 operate.

FIG. 15 is a circuit diagram showing another system configuration example of the same embodiment.

FIG. 16 is a circuit diagram showing a system configuration example of a sixth embodiment of a control device for a self-excited AC / DC converter according to the present invention.

17 is a time sequence diagram showing how internal signals of the limit value control circuit shown in FIG. 16 operate.

FIG. 18 is a time sequence diagram showing how internal signals of the limit value control circuit shown in FIG. 17 operate.

FIG. 19 is a circuit diagram showing a system configuration example of a control device for a conventional self-excited AC / DC converter.

FIG. 20 is a circuit diagram showing another system configuration example of a conventional control device for a self-excited AC / DC converter.

[Explanation of symbols]

1 ... AC system, 2, 28 ... Transformer, 3 ... Self-exciting AC / DC converter, 4 ... DC capacitor, 5 ... DC voltage detector, 6 ... DC voltage controller, 7 ... Active power Detector, 8
...... Active power controller, 9 ... Reactive power detector, 10 ...
Reactive power controller, 11 ... Selection circuit, 12 ... Arithmetic circuit, 13 ... PWM control circuit, 14 ... Pulse generator,
15 ... AC voltage detector, 16 ... AC voltage controller, 1
7 ... Converter control device, 18 ... Active power set value calculation circuit, 19 ... Separate excitation type AC / DC converter, 20 ... Phase advance control command signal, 21 ... Converter control device, 22 ... Phase advance command Circuit, 23 ... Phase advance controller, 24 ... DC current controller, 25 ... DC voltage controller, 26 ... Selection circuit,
27 ... Pulse generation circuit, 29 ... DC current detector, 3
0 ... DC voltage detector, 31, 45, 47, 57 ... Switch circuit, 32, 33, 39, 58, 74, 76, 8
5 ... Adder, 34, 38, 43 ... Sign inversion circuit, 3
5,40,44,46,72,73,82,83 ... 1
Next delay circuit, 36, 75, 84 ... Multiplier, 37 ... Active power detector, 41 ... Limiter circuit, 42 ... Average value calculation circuit, 48 ... Inversion circuit, 49 ... Condition circuit, 50
...... Power flow direction command signal for separately excited DC power transmission, 51, 52 ...
... Level detector, 53, 62 ... NOT circuit, 54, 5
5, 63, 69 ... AND circuit, 56 ... OR circuit, 5
9 ... Distortion detection circuit, 60, 80 ... On delay circuit, 61, 71, 81 ... Off delay circuit, 64 ...
Circuit breaker, 65 ... Capacitor, 66 ... Circuit breaker closing command signal, 67, 79 ... Limit value control circuit, 68, 86
...... Limiter circuit, 70 ...... One-shot signal generation circuit, 77 ...... Voltage set value calculation circuit, 78 …… Undervoltage relay, 87 …… Amplifier, Pref …… Active power set value, Q
ref …… Reactive power setting value, Edref …… DC voltage setting value,
Cm: PWM signal control rate, φ: PWM signal phase angle,
Idp: DC current set value of the separately excited AC / DC converter, Qmin,
Qmin '... Minimum reactive power limit value, ΔQmin ... Change in minimum reactive power limit value, REC / INV .... Direction direction signal signal for separately excited DC transmission, PL ... Actual power detected value for separately excited AC / DC converter , Prefx ... Total interchange power setting value for self-excited DC transmission and separately-excited DC transmission.

Claims (6)

[Claims] 1. A system in which a self-excited DC transmission system and a separately-excited DC transmission system are installed in parallel, and in a control device for a self-excited AC / DC converter applied to the self-excited DC transmission system,
A circuit is provided for changing the active power set value of the self-excited DC transmission system by a predetermined amount from a previous value on condition that the phase advance control is performed by the inverse converter of the separately excited DC transmission system. Control device for self-excited AC / DC converter. 2. A system in which a self-excited DC transmission system and a separately-excited DC transmission system are installed in parallel, and in a controller for a self-excited AC / DC converter applied to the self-excited DC transmission system,
From the set value of the interchange power that combines the separately excited DC transmission system and the self-excited DC transmission system, a value obtained by subtracting the value of the power actually interchanged by the separately excited DC transmission system from the self-excited DC transmission system is set. A control device for a self-excited AC / DC converter, which is provided with a circuit used as an active power set value. 3. A control system for a self-excited AC / DC converter applied to a self-excited DC transmission system, comprising a system in which a self-excited DC transmission system and a separately excited DC transmission system are installed in parallel.
A self-excited type characterized in that a circuit is provided for changing the active power set value and the reactive power set value of the self-excited DC transmission system, and switching the changing speed according to an operating state signal of the separately excited DC transmission system. Control device for AC / DC converter. 4. A controller for a self-excited AC / DC converter,
When a separately excited AC / DC converter installed in or near the same AC bus as the self-excited AC / DC converter is operated as an inverse converter to perform phase advance control, or when phase advance control may be performed, The reactive power operating point of the self-excited AC / DC converter is set on condition that the phase advance control start signal or the distortion of the AC voltage is a certain value or more, and the separately excited AC / DC converter is in the inverse converter operating state. A control device for a self-excited AC / DC converter, characterized in that a circuit for changing the direction of the forward reactive power is provided. 5. In a control device for a self-excited AC / DC converter performing AC voltage control, a separately excited AC / DC converter is connected to or near the same AC bus as the self-excited AC / DC converter, and a capacitor is provided in an AC system in the vicinity thereof. Is performed, the output limit value of the AC voltage control circuit of the self-excited AC / DC converter is determined by the logical product condition of the command signal of the capacitor and the status signal that the separately excited AC / DC converter is operating as an inverse converter. And a circuit for changing the magnitude of the AC voltage set value given to the AC voltage control circuit of the self-excited AC / DC converter to a large value. Control device. 6. A control device for a self-excited AC / DC converter that performs AC voltage control, when detecting that the voltage of the connected AC system has dropped below a certain value, the output limit value of the AC voltage control circuit is changed. A control device for a self-excited AC / DC converter, which is provided with a circuit for changing to a zero direction.