JPH08237869A - Power converter - Google Patents

Abstract

PURPOSE: To rapidly recover power transmission at the time of removing an accident by outputting a third phase control signal to power converting means by using an open loop phase control information signal and a closed loop phase control information signal. CONSTITUTION: An open loop capability angle control circuit 1301 calculates a control angle to have the capability angle of a necessary minimum limit in a closed loop based on the DC current detected value of a DC current transformer 101 and the AC voltage detected value of an AC voltage transformer 100, and outputs a first phase control signal α1. A closed loop capability angle control circuit 1304 controls a capability angle to the value of a set value or more according to the capability angle actually measured value γmes from a real capability angle detector and the set value γref of the capability angle. Thus, the commutation failure owing to the phase abrupt change of the voltage and the current can be prevented, power can be provided as much as possible during the power converting, and power transmission can be rapidly recovered at the time of removing the accident.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power converter for converting a direct current to a direct current or a direct current to an alternating current in a direct current power transmission or an asynchronous interconnection facility, and particularly to stop the power conversion in the event of an alternating current system accident or a direct current system accident. The present invention relates to a power conversion device that can be operated without doing so.

[0002]

2. Description of the Related Art DC power transmission or asynchronous interconnection equipment is usually
In a power conversion device that performs a forward conversion operation that converts alternating current to direct current, the current of the direct current circuit is controlled so that the specified transmission power is obtained, and in a power conversion device that performs an inverter operation that converts direct current to alternating current, The operation is performed so as to control the voltage to a specified value.

As a backup during inverter operation, when the AC voltage drops due to an AC system accident,
A control angle for maintaining the minimum margin angle required for commutation operation based on the AC voltage (commutation voltage) and DC current for stable operation of the inverter when the DC current increases due to a DC transmission line accident. A margin angle control circuit for calculating In order to enable power transmission as long as the inverter can be continuously operated even in the case of an AC system accident, it is necessary to constantly monitor this margin angle during the operation of the inverter and perform control to always keep the minimum value. In order to recover power as quickly as possible when removing an AC system fault, it is necessary to quickly return the control angle to the steady-state value while maintaining the minimum necessary margin angle when recovering the voltage when eliminating the accident. Is.

Conventionally, in order to perform stable operation while keeping the margin angle of the inverter at a required minimum value, the margin angle is constantly measured,
It is considered to perform closed-loop allowance control that keeps this constant. However, in closed-loop margin angle control, the detection result of the margin angle is not immediately applied to the margin angle control,
The detection result is used for determining the next control angle after at least one cycle, and the control is always delayed. As a result, there is a possibility that the inverter may fail commutation due to instantaneous voltage waveform distortion or sudden voltage phase change. On the other hand, a method of performing open-loop margin angle control for calculating a control angle necessary for maintaining a minimum margin angle in open loop from a commutation voltage applied to the inverter and a current flowing through the inverter is disclosed in, for example, Japanese Patent Laid-Open No. 6-269.
It is considered to be No. 175. With this control method, commutation failure can be prevented to some extent because the response to the change in the AC voltage or the change in the DC current is fast. However, since it is necessary to maintain a sufficient margin angle to prevent commutation failure even with respect to voltage waveform distortion and sudden phase change of voltage, the control angle must be set to a value with a large margin. There is a problem that the transmission power at the time of the AC system accident or the DC system accident becomes small, and thus the recovery of the transmission power at the time of eliminating the accident becomes slow.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to allow the power conversion device to continue operating in the event of an AC system fault or a DC system fault, and to transmit as much power as possible.
An object of the present invention is to provide a power conversion device that can recover power transmission at high speed when an accident is removed.

[0006]

In order to achieve the above object, in the present invention, a phase control signal is inputted to convert DC power into AC power or AC power into DC power, for example, other means. In a power conversion device equipped with power conversion means such as a thyristor valve element using a thyristor element as an excitation power conversion element, a closed loop phase for detecting an actual margin angle state of the power conversion means and outputting a first phase control information signal. Open loop phase control signal output means for detecting a control signal output means, a voltage state applied to the power conversion means, and a current state flowing in the power conversion means, and outputting a second phase control information signal, and a closed loop. By using the first phase control signal from the phase control signal output means and the second phase control signal from the open loop phase control signal output means, a third phase control signal is supplied to the power conversion means. Is obtained so as to output a phase control signal.

Further, the power converter of the present invention detects the current state of the power line through which the DC power flows, inputs this current state, and further sends a phase control information signal to the power conversion means for control. It is the one.

Further, the voltage state of the power line through which the DC power flows is detected, this power state is input, and further, a phase control information signal is sent to the power conversion means for control.

Further, in the power converter of the present invention, the first phase control signal is added to correct the second phase control signal to make a third phase control signal, and this signal is used. The power conversion means is controlled.

The closed loop phase control signal output means is provided with an attenuation means for gradually reducing the first phase control signal value after outputting the first phase control signal.

The open loop phase control signal output means is provided with an attenuation means for gradually reducing the second phase control information signal value after outputting the second phase control information signal.

Further, the closed-loop phase control signal output means, when the power converting means converts the DC power into a plurality of phases of AC power or the plurality of phases of AC power into a DC power, the detected margins for each of the plurality of phases. The first phase control signal is obtained by using the minimum margin angle information among the angles.

The open loop phase control signal output means detects the voltage effective for each of the plurality of phases when the power conversion means converts the DC power into a plurality of phases of AC power or the plurality of phases of the AC power into a DC power. The value or the minimum value information of the voltage for each of the above multiple phases is used to obtain the second phase control signal.

Next, the actual margin angle signal from the closed loop phase control signal output means is compared with the predetermined phase margin angle information, and when the deviations are equal to or more than a certain value, the first phase control information signal is changed to the first phase control information signal. The two phase control information signals are added for correction. Furthermore, when operating a device such as a star converter or a transformer, or separately from this, or when detecting a commutation failure state of the power conversion means at the same time, a phase control advance means for advancing the phase control angle of the power conversion means is provided in advance, The first phase control information signal by the closed loop phase control signal output means and the third phase control signal using the second phase control information signal by the open loop are added so as to correct the output signal.

As another invention, a closed loop phase control signal output means for detecting the actual margin angle state of the power conversion means and outputting a second phase control information signal, a voltage state applied to the power conversion means, An open loop phase control signal output means for outputting a second phase control information signal and a current state of DC power of a power line connected to the power conversion means are detected by detecting a current state flowing through the power conversion means. , A current phase control means for sending a phase control information signal to the power conversion means using this current information, and a voltage state of DC power is detected, and a phase control information signal is sent to the power conversion means using this voltage information Voltage phase control means, first phase control signal and second
Phase margin control means for outputting a third phase control signal, the third phase control signal, the phase control signal from the voltage phase control means, and the phase from the current phase control means. And a signal selecting means for selecting an optimum control signal among the control signals.

[0016]

According to the present invention, by using the first phase control information signal from the open loop phase control signal output means and the second phase control information signal from the closed loop phase control signal output means,
Since the third phase control signal is output to the power conversion means, the open loop phase control signal output means performs control for ensuring the minimum necessary margin angle, and the closed loop signal phase control is used to perform actual control. Since the margin angle is controlled, it becomes possible to prevent the commutation failure due to the occurrence of distortion in the voltage / current waveform in the AC system or the DC system, the sudden change in the phase of the voltage and the electric wave, and the power conversion. Electric power can be transmitted as much as possible even during operation, and power can be restored at high speed when the accident is cleared.

Further, according to the power converter of the present invention, since the current state of the DC power is detected, the control angle for keeping the current at a predetermined constant value is output. It becomes possible to control so that the current state of the electric power is preferentially determined.

Further, since the voltage state of the DC power is detected, a control angle for keeping the voltage state at a predetermined state is output, so that the voltage state of the DC power is preferentially determined according to the power conversion state. It becomes possible to control.

Further, according to the present invention, the optimum phase is obtained by adding the phase control signal for controlling the power conversion means in order to correct the first phase control signal and the second phase control signal. The control signal is calculated.

Further, according to the present invention, since the closed loop phase control signal output means outputs the first phase control signal and then gradually reduces the first phase control signal value, it is possible to speed up at the time of an accident. Even when power transmission is restored, it is possible to suppress transient fluctuations in power transmission.

According to the present invention, after the open loop phase control signal output means outputs the second phase control information signal,
Since the second phase control information signal value is gradually reduced, it is possible to suppress transient fluctuations in power transmission even when power transmission is quickly restored in the event of an accident.

Further, according to the present invention, the closed loop phase control signal output means is detected when the power converting means converts the DC power into the plural-phase AC power or converts the plural-phase AC power into the DC power. Since the first phase control signal is obtained using the minimum margin angle information of the margin angles for each of the plurality of phases, the element with the smallest margin angle among the power conversion elements converting each phase. However, this element is controlled so as not to fail in conversion.

Further, according to the present invention, the open-loop phase control signal output means is detected when the power conversion means converts DC power into a plurality of phases of AC power or a plurality of phases of AC power into DC power. Since the second phase control signal is obtained using the voltage effective value for each of the plurality of phases or the minimum value information of the voltage for each of the plurality of phases, among the power conversion elements converting each phase, Although the element in the minimum margin angle state will fail in conversion, this element is controlled so as not to fail in conversion.

The constant current control means commands the control angle for keeping the current of the DC circuit constant at a specified value during the forward conversion operation of the power converter. The constant voltage control means commands a control angle for keeping the voltage of the DC circuit at a specified constant value when the power converter is operating the inverter. The allowance angle control means commands a control angle for always maintaining the allowance angle at a prescribed constant value that is the minimum allowance angle when the power converter is in the inverter operation. The signal selection unit selects the constant current control unit or the constant voltage control unit according to the forward conversion operation or the inverter operation of the power conversion device. Further, the output of the margin angle control means is selected when the power conversion device runs short of the margin angle during operation of the inverter.

The margin angle control means comprises a closed loop margin angle control means and an open loop margin angle control means. The actual margin angle detecting means detects the margin angle of each phase of the thyristor valve. The closed loop margin angle control means outputs the shortage of the control angle so that the minimum margin angle of the detected margin angles of each phase does not become equal to or less than the preset minimum margin angle. The open loop margin angle control means calculates and outputs a control angle required to maintain a specified margin angle from the current flowing through the power converter and the commutation voltage applied to the power converter. The margin angle shortage detection means outputs the amount of control advance angle for the shortage in order to maintain the actual margin angle at or above the specified minimum margin angle only when the actual margin angle is insufficient, as output from the closed loop margin angle control means. . First
The addition means adds the output of the margin angle shortage detection means to the output of the open loop margin angle control means as a correction value, and when the actual margin angle is insufficient, the control angle advance angle is increased to compensate for the lack of the actual margin angle.

Further, in the present invention, when the commutation failure is detected at the time of operating the equipment such as the star converter, the transformer or the like, or separately from this, and at the same time when the commutation failure is detected, the phase control of the conversion means is performed by the predetermined angle. The angle is advanced to prevent commutation failure of the power conversion means due to waveform distortion.

Further, in the present invention, the control information signal from the open loop phase control signal output means, the closed loop phase control signal output means, the control signal from the current phase control means, and the control signal from the voltage phase control means. By selecting the most suitable control signal among them, the most suitable control signal can be obtained according to the fluctuation state.

[0028]

FIG. 1 shows an embodiment of the present invention. Describing according to the numbers, 10 is an AC system, for example, an AC system 1 having a three-phase AC as an AC phase of a coefficient, 20 is a similar AC system 2, 11 and 21 are conversion transformers, and 12 and 22 are AC or DC. A thyristor element of a power conversion element as a power conversion means for converting power into AC, 31 and 32 are DC reactors that smooth DC current, and 40 is a DC power transmission line (in the case of asynchronous interconnection equipment, power conversion devices 12 and 22 are connected. 100 is an AC voltage transformer that detects the voltage of the AC system 1, 101 is a DC current transformer that detects the current of the DC circuit, and 110 is an electric power converter that receives the output of the DC current transformer 101. A constant current control circuit for keeping the current flowing in 12 at a specified value, 102 is a direct current converter of the power conversion device, which is connected to the power transmission line side of a DC reactor in a forward conversion operation for converting AC into DC. A DC voltage transformer for detecting a voltage, this case indicates taking the case where power converter 22 is sequentially converted operation example. 120 receives this DC voltage detection value,
A constant voltage control circuit for maintaining this voltage at a specified constant value,
Reference numeral 130 denotes a margin control circuit for keeping the margin of the inverter constant, which is an open loop margin control circuit 1 described below.
301, a closed loop margin control circuit 1304, and an addition circuit 1305. Open loop margin control circuit 1
Reference numeral 301 calculates a control angle for maintaining a minimum necessary margin angle in an open loop based on the detected value of the DC current of the DC current transformer 101 and the detected value of the AC voltage of the AC voltage transformer 100,
Output the phase control signal α1. The closed-loop margin angle control circuit 1304 uses the margin angle actual measurement value γmes from the actual margin angle detection device (not shown) and the margin angle set value γref to control the margin angle to a value equal to or larger than the set value. Margin angle deviation detection circuit 1302 for obtaining the deviation between γmes and margin angle set value γref
And a margin angle correction signal generation circuit 1303 that outputs the control advance angle amount for securing the insufficient margin angle only when the margin angle is insufficient. The output of the open loop margin angle control circuit 1301 and the second phase control signal α2, which is the output from the margin angle correction signal generation circuit 1303, are added to the addition circuit 130.
5 is added and the result is the output of the allowance angle control circuit 130. Here, the AC voltage E which is the input signal of the margin angle control circuit 130
ac is the voltage effective value of each phase of the YY and YΔ windings of the transformer, or the minimum value of the magnitude of each phase voltage. Further, the actual margin angle detection circuit (not shown) can directly measure the margin angle from the voltage difference applied to the power conversion element of each phase or the current state, or can be obtained from the AC voltage and the DC current. The actual margin angle γmes of the input signal is calculated by using the minimum measured margin angle value of each phase. This is because the power conversion element (thyristor valve) having the minimum margin angle fails to commutate, and therefore the margin angle control circuit should control so that this valve does not fail commutation.

A signal selection 140 receives the output of the constant current control circuit 110, the output signals of the constant voltage control circuit 120 and the margin angle control circuit 130, and selects, for example, the minimum margin control signal as an appropriate output among them. A circuit, 150 is a pulse phase control circuit which outputs a pulse having a phase proportional to the magnitude of the output signal selected by the signal selection circuit 140.

It is assumed that the same control circuit as this is also provided in the power conversion means 22 at the other end. Here, the power converter 12 converts the direct current into the alternating current (inverter).
A case where the operation and power conversion device 22 performs a forward conversion operation of converting alternating current into direct current will be described as an example.

Therefore, during normal operation, the detailed control device is not shown in the power conversion means 22, but the control output corresponding to the constant current control circuit 110 in the control device of the power conversion device 12 is the signal selection circuit 140. Is selected by the signal selection circuit corresponding to, and controls the current of the DC transmission line. On the other hand, in the inverter-operated power conversion device 12, the output of the constant voltage control circuit 120 is selected by the signal selection circuit 140 to control the DC voltage of the DC transmission line. During normal operation, the inverter is under constant voltage control as described above, and the control angle during constant voltage control is smaller than the control angle during margin angle control (the control advance angle is large), so there is a sufficient margin angle. Is secured. Here, in order to clarify the relationship between the control angle and the control advance angle, description will be given based on the characteristics of the pulse phase control circuit.

Input signal Ec of pulse phase control circuit 150
2 shows an example of the phase angle characteristic of the output pulse with respect to. The horizontal axis represents the input signal, and the vertical axis represents the phase angle (control angle) α of the output pulse. Ecmin (αmin) to Ecmax (αm
The example of the linear characteristic is shown in the range of ax). Here, αmin is a value of 5 degrees and αmax is a value of about 170 degrees. Normally, during the forward conversion operation, the phase control angle is operated within a range of αmin to 90 degrees. When the inverter is operating, 90 degrees to αmax
It is operated in the range of. Here, the control angle α is a value from α = 0 degrees, the control advance angle β is a control angle during inverter operation, and is a value from α = 180 degrees. Therefore, there is a relationship of α = π−β between α and β. The control angle in the constant voltage control described above is smaller than the control angle in the margin control, and thus the control advance angle β is a large value.

Next, the allowance angle control circuit during inverter operation will be described. The margin angle control operates when the AC voltage becomes low due to an AC system accident or the like, or the constant voltage control becomes ineffective when the DC current becomes excessive due to a DC transmission line accident. That is, because the AC lead voltage is reduced, the control lead angle β is reduced to maintain the DC voltage of the DC transmission line at a specified value.However, if the control lead angle is reduced, the margin angle is reduced and constant voltage control cannot be performed. Angle control works. A similar phenomenon occurs when the direct current becomes excessive. The relationship between the control lead angle and the allowance angle is expressed by the following equation.

[0034]

[Equation 1]

Where β: control lead angle γ: allowance angle X: commutation reactance Id: DC current Eac: AC voltage From the above equation, the control lead angle required to maintain the specified allowance angle when the AC voltage becomes low is growing. Further, as the current increases, the control advance angle also increases for the same AC voltage.

FIG. 3 shows a characteristic example of the open-loop allowance angle control circuit 1301 in the allowance angle control for ensuring an allowance angle with respect to changes in AC voltage and changes in DC current. The horizontal axis represents the magnitude of the AC voltage, and the vertical axis represents the control advance angle β (= π-α).
It is the figure which took and represented. The parameter is the direct current Id. This curve is based on the following equation set as γ = γmin (minimum margin angle) in the above equation. Therefore, the control advance angle β is also indicated by βm.

[0037]

[Equation 2]

Here, βm is the control lead angle required to maintain the minimum margin angle γmin. The calculation method is based on the above equation from the detected values of the AC voltage Eac and the DC current Id because γmin and X are fixed constant values. Since the control lead angle βm for securing the minimum margin angle is obtained by performing the calculation, the control lead angle is calculated in advance based on the AC voltage and the DC current, and is made into a table, and the AC voltage Eac and the DC current Id are calculated. The control advance angle βm can be obtained from the detected value of (1) by the table index. Further, it may be calculated based on the detected values of the AC voltage Eac and the DC current Id from the equation of a straight line obtained by linearly approximating the curve of FIG. It is also possible to directly calculate according to the magnitudes of the AC voltage and the DC current according to the above equation.

Next, the operation of the control circuit at the time of an AC system fault will be described with reference to FIG.

FIG. 4 shows the voltage (minimum voltage of each phase) Eac of the AC system to which the inverter is connected, the output signal α1 of the first phase control signal from the open loop margin angle control circuit.
The difference Δγ between the actual margin angle γmes and the margin angle reference value γref, the output signal α2 of the second phase control signal from the margin angle correction signal creating circuit, and the output signal α3 of the third phase control signal from the margin angle control circuit. (= Α1 + α2) is shown. It is assumed that the DC current is constantly controlled by the operation of the power conversion device that performs the forward conversion operation even during the accident period, but even if it fluctuates, the following description does not make a difference.

Now, consider a case where the power conversion device 12 is operating as an inverter for converting direct current into alternating current. At time t0 before the accident occurs in the AC system, the output of the constant voltage control circuit of the inverter is smaller than the output of the margin angle control circuit (the control advance angle is large), and the output of the constant voltage control circuit of the signal selection circuit is It is selected and the inverter is under constant voltage control. If an accident occurs in the AC system on the inverter side at time t1 and the AC voltage drops, the inverter cannot control the DC voltage to a specified value. In order to maintain the specified minimum margin angle when the AC voltage drops in the open loop margin angle control circuit,
The control angle is reduced in accordance with the characteristics shown in FIG. Therefore, the margin angle control circuit is selected, and the inverter operates in the margin angle control operation. The open-loop margin angle control circuit cannot operate instantaneously due to a delay in voltage detection, a delay in control operation, or the like due to an instantaneous drop in AC voltage due to an accident, and therefore the control angle command is delayed and the inverter fails in commutation. When commutation failure occurs, the actual margin angle becomes zero, and the output α2 of the margin angle correction signal generating circuit appears. This signal is output from the open loop margin angle control circuit α1.
Added to. When the required margin angle is secured by the open loop margin angle control circuit output α1 and the margin angle correction signal generation circuit output α2, the commutation failure is recovered, and the margin angle deviation Δ at time t2.
γ becomes positive. The output of the margin angle correction signal generating circuit becomes zero at this point, but in actual application, as shown in FIG. 4, it is a new transfer characteristic that a time constant circuit is provided as a damping means to return it to zero. It is preferable for preventing flow failure. Therefore, the margin angle correction signal generating circuit also has a characteristic that the control angle α2 is not instantly returned when the margin angle is secured, but the second phase control signal is gradually returned. When the AC system fault is removed at time t3, the AC voltage recovers,
As a result, the open loop margin angle control circuit output α1 also returns to the original control angle value. Also in this case, when the control angle is advanced (the control advance angle is increased) with respect to the decrease of the AC voltage, the instantaneous characteristic is used, but when it is returned, it is actually applied by providing it with a time constant circuit as a damping means. It is preferable to prevent commutation failure. FIG. 5 shows an embodiment of a concrete AC voltage detecting circuit for realizing this characteristic. The input AC voltage Eac is the minimum value of the AC voltage effective value or the AC voltage magnitude detection value for each phase. Reference numeral 1310 is a first-order lag circuit. By setting the lag time constant of this circuit, the return of the control angle at the time of AC voltage recovery can be set. Reference numeral 1311 denotes a minimum value selection circuit, which outputs the smaller value of the AC voltage detection value and the first-order delay circuit output. Therefore, when the AC voltage drops, the AC voltage detection value is output as it is, and when the AC voltage is recovered, a signal is output via the first-order delay circuit, and the above-described characteristics can be realized. The control angle command α shown in FIG. 4 is obtained by performing the calculation explained in FIG. 3 using this output Eac ′.
The characteristic of 1 is obtained. Due to the recovery of the AC voltage, the actual margin angle also increases and the margin angle deviation Δγ also increases positively. The return of the control angle after the accident is removed is controlled by the open-loop margin angle control to return at a high speed according to the voltage recovery, so that the power recovery can be accelerated.

As described above, the open-loop allowance angle control controls the control angle at high speed with respect to changes in the AC voltage and the DC current, and the closed-loop allowance angle control has the allowance angle control characteristic of preventing continuous commutation failure. As a result, it is possible to prevent commutation failure even in the case of an AC system accident, to perform stable power transmission, and to speed up recovery of electric power when the AC system accident is eliminated. The open-loop margin angle control has a control characteristic that secures the minimum required source margin angle, and the closed-loop margin angle control increases the control angle when the margin angle is insufficient to secure the margin angle, thereby maximizing the transmission power during an accident. In addition to the above, it is possible to speed up recovery of electric power when the AC system fault is removed.

Another embodiment of the present invention is shown in FIG. Only the margin angle control circuit is shown in the figure, and the other parts have the same configuration as in FIG. In the figure, when AC voltage waveform distortion occurs due to operation of equipment such as transformer and stacon, or commutation failure, etc., commutation failure from equipment operation command or commutation monitoring circuit not shown to monitor commutation status An embodiment of a control device provided with a circuit for advancing the control angle of the inverter in advance by a detection signal or the like is shown. The same numbers as in FIG. 1 indicate the same functions, so new numbers will be described. Reference numeral 1321 denotes a control angle advancing circuit for outputting a signal for advancing the output of the margin angle control circuit by a certain set control angle in response to a device operation command such as a transformer or a stacon or a commutation failure detection signal, and 1322 the margin angle control circuit. Is a second adder circuit for adding the output of the control angle advancing circuit to the output of. The output of the adder circuit is connected to the signal selection circuit 140. With this circuit, when a device is operated or a commutation failure occurs, a previously set control angle, for example, 15 degrees is added to the control angle command value that is the current output of the margin angle control circuit. The flow failure can be prevented in advance.

Another embodiment is shown in FIG. In FIG. 7, a second signal selection circuit is provided in the constant voltage control circuit and the margin angle control circuit that are controls during inverter operation, and the output of this circuit is added to the output of the control angle advance circuit. . Reference numeral 1331 in the figure is a second signal selection circuit that receives the outputs of the constant voltage control circuit 120 and the margin angle control circuit as input, and selects the output of the smaller of the control angles (larger of the control advance angles), or 1332. A third adder circuit for adding the output of the control angle advance circuit 1321 and the output of the second signal selection circuit 1331. Also with this configuration, since the control angle command value of the inverter is advanced by the specified control angle in advance when the AC voltage waveform distortion occurs, the commutation failure can be prevented as in the case of FIG. 6.

[0045]

[Effects of the Invention] In the event of an AC system accident, operation can be continued without stopping the power converter. Furthermore, with open-loop margin control, it has a control characteristic to secure the margin angle of the minimum required source,
When the margin angle is insufficient, the control angle is increased by the closed loop margin angle control to secure the margin angle, so that the power transmitted by the power converter during an accident can be maximized, and the Recovery can be fast.

[Brief description of drawings]

FIG. 1 is a DC power transmission device including a control device for a power converter according to the present invention.

FIG. 2 shows an example of characteristics of the pulse phase control device of FIG.

3 is a characteristic of the open loop margin control circuit of FIG.

FIG. 4 is a diagram for explaining the operation of the control device for the power converter according to the present invention.

FIG. 5 shows an example of an AC voltage detection circuit.

FIG. 6 shows another embodiment of the control circuit.

FIG. 7 shows another embodiment of the control circuit.

[Explanation of symbols]

10 ... AC system 1, 20 ... AC system 2, 11, 21 ... Conversion transformer, 12, 22 ... Power conversion device, 31, 32 ...
DC reactor, 40 ... DC transmission line, 100 ... AC voltage transformer, 101 ... DC current transformer, 110 ... Constant current control circuit, 102 ... DC voltage transformer, 120 ... Constant voltage control circuit, 130 ... Margin angle control circuit , 1301 ... Open loop margin angle control circuit, 1302 ... Margin angle deviation detection circuit, 1303 ... Margin angle correction signal creating circuit, 1304 ... Closed loop margin angle control circuit, 1305 ... Addition circuit, 140 ... Signal selection circuit, 1
50 ... Pulse phase control circuit, 1321 ... Control angle advancing circuit, 1322 ... Second addition circuit, 1310 ... First-order lag circuit, 1311 ... Minimum value selection circuit, 1331 ... Second signal selection circuit, 1332 ... Third addition Circuit, Eac ... AC system voltage, α1 ... Output signal of open loop margin angle control circuit, Δ
γ ... The difference between the actual margin angle γmes and the margin angle reference value γref, α2 ...
Insufficient margin angle detection circuit output, α3 (= α1 + α2) ... Margin angle control circuit output.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroo Konishi 7-1, 1-1 Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Tadao Kawai 1-chome, Kokubun-cho, Hitachi-shi, Ibaraki No. 1 Inside the Hitachi Kokubun Plant (72) Inventor Masahiko Amano 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture Hitachi Ltd. Hitachi Research Laboratory (72) Inventor Masamori Nobayashi Osaka, Kita, Osaka 3-3-22 Nakanoshima-ku, Kansai Electric Power Co., Inc. (72) Inventor Koji Yamaji 2-5 Marunouchi, Takamatsu, Kagawa Prefecture Shikoku Electric Power Co., Inc. (72) Kazuo Kato 6-15-1, Ginza, Chuo-ku, Tokyo No. Power Supply Development Co., Ltd.

Claims (18)

[Claims] 1. A power conversion device comprising a power conversion means for inputting a phase control signal to convert DC power into AC power or AC power into DC power. An open-loop phase control signal output means for detecting a current state flowing in the power conversion means and outputting a first phase control signal; and a margin angle state of the power conversion means for detecting a second phase Using a closed loop phase control signal output means for outputting a control signal, a first phase control signal from the open loop phase control signal output means, and a second phase control signal from the closed loop phase control signal output means A power converter comprising a phase margin angle control means for outputting a third phase control signal to the power conversion means. 2. The power conversion device according to claim 1, further comprising a current state control means for detecting a current state of the DC power and sending a phase control signal to the power conversion means using the current state. Power converter equipped with. 3. The power converter according to claim 1 or 2, wherein a voltage state of the DC power is detected, and a voltage for sending a phase control signal to the power converter by using the voltage state. A power conversion device comprising a state control means. 4. The power converter according to claim 3, wherein the first phase control signal from the open loop phase control signal output means and the second phase control from the closed loop phase control signal output means. A phase control signal output unit that outputs a phase control signal to the power conversion unit using a signal, a phase control signal from the current state control unit, and a phase control signal from the voltage state control unit. A power conversion device characterized by: 5. The power converter according to claim 3, wherein the third phase control signal, the phase control signal from the current state control means, and the phase control signal from the voltage state control means are input. Then, the power conversion device is provided with a signal selection means for outputting an optimum control signal of the respective control signals to the power conversion means. 6. The power converter according to claim 1, wherein the closed loop phase control signal output means always detects an actual margin angle state of the power converter. 7. The power converter according to claim 1, wherein the power converter converts DC power into a plurality of phases of AC power, or converts a plurality of phases of AC power into DC power, and the closed loop phase. The power conversion device, wherein the control signal output means obtains the second phase control signal by using minimum margin angle information among the detected margin angles for each of the plurality of phases. 8. The power converter according to claim 1, wherein the power converter converts DC power into a plurality of phases of AC power, or converts a plurality of phases of AC power into DC power, and the open loop. The phase control signal output means obtains the first phase control signal by using the detected voltage effective value for each of the plurality of phases or minimum value information of the voltage for each of the plurality of phases. 9. The power converter according to claim 1, wherein the closed loop phase control signal output means outputs the first phase control information signal and then gradually the second phase control information signal. An electric power converter comprising an attenuator for reducing the value. 10. The power converter according to claim 1, wherein the open-loop phase control signal output means outputs the second phase control information signal and then gradually the first phase control information. An electric power converter comprising an attenuator for reducing a signal value. 11. The power converter according to claim 1, wherein the phase margin angle control means adds the first phase control information signal and the second phase control information signal to obtain the first phase control information signal. Three
An electric power converter that outputs the phase control signal of. 12. The power converter according to claim 9, wherein the margin angle state of the power converter means by the closed loop is compared with a predetermined margin angle state, and when these deviations are not less than a certain value, The power converter apparatus, wherein the phase margin angle control means adds the first phase control information signal and the second phase control information signal. 13. The power conversion device according to any one of claims 1 to 12, wherein the phase of the power conversion device is advanced when the device forming the power conversion device is operated or when the commutation of the power conversion device fails. A power conversion device comprising a control angle advance circuit for outputting a phase advance signal, and adding the phase advance signal from the control angle advance circuit to the third phase control information signal. 14. The power converter according to claim 13, wherein the control signal from the voltage phase control means, the closed loop phase control signal output means and the open loop phase control signal output means are used. A first signal selection circuit for selecting an optimum value of the phase control signals of the above, and a signal from the control angle advancing circuit is added to the phase control signal from the first signal selection circuit, and the added phase control is performed. A second signal selection circuit for selecting a signal and a phase control signal from the current control means, wherein the power conversion means is controlled by the phase control signal from the second signal selection circuit. Power converter. 15. The power conversion device according to claim 13 or 14, wherein a device such as a power converter is provided with a star converter and a transformer. 16. A power conversion device comprising power conversion means for inputting a phase control signal to convert DC power into AC power or AC power into DC power, wherein a voltage state applied to the power conversion means An open loop phase control signal output means for detecting a current state flowing in the power conversion means and outputting a first phase control information signal; and a margin angle state of the power conversion means for detecting a second angle A closed loop phase control signal output means for outputting a phase control information signal, a current phase control means for detecting a current state of the DC power, and sending a phase control information signal to the power conversion means using the current information, A voltage phase control means for detecting a voltage state of the DC power and transmitting a phase control information signal to the power conversion means using the voltage information; and a first phase from the open loop phase control signal output means. Second from the control signal and the closed loop phase control signal output means
And a phase margin signal control means for outputting a third phase control signal to the power conversion means, the third phase control signal, and the phase control signal from the voltage phase control means. , A signal selecting means for selecting an optimum control signal among the phase control signals from the current phase controlling means. 17. The power conversion device according to claim 1 or 16, further comprising a separately excited power conversion element as the power conversion means. 18. The power conversion device according to claim 17, further comprising a thyristor element as the separately excited power conversion element.