JP3533515B2 - Series compensator and switching element controller - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a series compensator and a switching element controller, and more particularly to controlling the operation of a switching element connected in parallel with an AC reactor to a series capacitor inserted in an AC power transmission line. The present invention relates to a suitable series compensation device and a switching element control device.

[0002]

2. Description of the Related Art In an AC system composed of an AC power transmission line, it is effective to improve the steady stability and transient stability of the AC power transmission line, and series compensation is performed by inserting a series capacitor in series to the AC power transmission line. The system has been adopted. This system is mainly used in Northern Europe and North and South America, where many long-distance transmission lines are used.

When the series compensation system is applied to an AC transmission line, if the amount of compensation is increased in order to increase the compensation effect, the electricity generated by L (inductance) of the transmission line or generator and C (capacity) of the series compensator is increased. The typical resonance frequency approaches the commercial frequency, and shaft twist (SSR) of the generator becomes a problem. As a countermeasure against this, a thyristor-controlled series capacitor (TCS that changes the capacity of the series capacitor with a thyristor) is used.
C) was developed mainly by the Electric Power Research Institute (EPRI) in the United States, and field verification tests are being conducted. If the results of overseas operations such as this demonstration test are accumulated, it is possible that thyristor-controlled series capacitors will be used for voltage stability and stability improvement in the Japanese power system where voltage stability is a problem under heavy load. Is big.

[0004]

In order to fully bring out the effect of the thyristor-controlled series capacitor, it is necessary to stabilize the operation at the time of system failure and at the time of system failure removal. Therefore, conventionally, in the event of a system failure, an arrester or
It is considered that the thyristor is protected by a short circuit due to full conduction. However, after the fault in the system is eliminated, the fault current is reduced, and even if the protective action ends, it is difficult for the thyris to return to its original action immediately. This depends on the type of failure and whether the failure point is near or far from the thyristor-controlled series capacitor, but if the DC component or harmonic current is superimposed on the fault current, the firing phase of the thyristor will be detected. It is difficult to ignite the thyristor with an appropriate phase. Thyristor control If a thyristor that constitutes a series capacitor is not properly operated at the time of an accident or removal of an accident in the system, the operation of the thyristor will adversely affect the system and prolong the recovery from the accident. Become.

An object of the present invention is to provide a series compensating device and a switching element control device which can appropriately perform the operation of the switching element when a system fault occurs and when the fault is eliminated.

[0006]

In order to achieve the above object, the present invention provides a series capacitor inserted in series in an AC power transmission line, an AC reactor connected in parallel with the series capacitor, and an AC reactor. A switching element that is connected in series and controls the phase of a current flowing through the AC reactor in response to an ignition pulse signal, an electric signal detection unit that detects an electric signal of the AC transmission line, a command value and the electric signal detection. Command value generating means for calculating a firing phase angle for the switching element according to a deviation from the detected value of the means, and generating a command value of the control angle according to the calculation result,
Failure detection means for detecting a failure of the AC system based on the electric signal of the AC transmission line, and synchronization pulse signal generation means for generating a synchronization pulse signal synchronized with the electric signal in response to the electric signal of the AC transmission line. A control voltage generating means for generating a control voltage according to the phase difference between the reference pulse signal and the synchronizing pulse signal, and a failure of the AC system due to the failure detecting means among the control voltages generated by the control voltage generating means. A control voltage storage means for storing the control voltage generated before being detected, and a control voltage stored in the control voltage storage means in response to the failure detection output of the failure detection means, and otherwise selected Control voltage selecting means for selecting the control voltage generated by the control voltage generating means, and a pulse signal having an oscillation frequency corresponding to the control voltage selected by the control voltage selecting means. Voltage control oscillating means, a reference pulse signal generating means for generating a reference pulse signal according to an output pulse signal of the voltage controlling oscillating means, and a reference pulse signal generating means for generating a command value generated by the command value generating means. And a pulse phase shifting means for generating a firing pulse signal and outputting the firing pulse signal to the switching element.

In constructing the series compensation device,
Instead of the electric signal detection means, a current detection means for detecting the current of the AC transmission line, a voltage detection means for detecting the voltage of the AC transmission line, an alternating current from the detection current of the current detection means and the detection voltage of the voltage detection means Impedance calculation means for calculating the impedance of the power transmission line is provided, and instead of the command value generation means, the ignition phase angle for the switching element is calculated according to the deviation between the impedance command value and the calculated value of the impedance calculation means. A command value generating means for generating a command value of the control angle according to the calculation result is provided, and further,
Instead of the reference pulse signal generation means, reference pulse signal generation means for dividing the output pulse signal of the voltage controlled oscillation means to generate a reference pulse signal may be provided.

Also, the present invention is directed to an electric signal detecting means for detecting an electric signal of an AC power transmission line, a command value of an ignition phase angle for a switching element inserted in the AC power transmission line, and a detection of the electric signal detecting means. Command value generation means for generating a command value of the control angle according to the calculated value and a deviation according to the calculation result, and failure detection means for detecting a failure of the AC system based on the electric signal of the AC transmission line. , A synchronous pulse signal generating means for generating a synchronous pulse signal in synchronization with the electric signal of the AC transmission line, and a control voltage according to the phase difference between the reference pulse signal and the synchronous pulse signal And a control voltage memory for storing the control voltage generated before the failure of the AC system is detected by the failure detection means among the control voltages generated by the control voltage generation means. And a control voltage selection that selects the control voltage stored in the control voltage storage means in response to the failure detection output of the failure detection means and otherwise selects the control voltage generated by the control voltage generation means. Means, a voltage control oscillation means for outputting a pulse signal having an oscillation frequency according to the control voltage selected by the control voltage selection means, and a reference pulse signal for generating a reference pulse signal according to the output pulse signal of the voltage control oscillation means. A pulse for generating a firing pulse signal by shifting the reference pulse signal generated by the reference pulse signal generation means according to the command value generated by the generation means and the command value generation means, and outputting the firing pulse signal to the switching element. The present invention constitutes a switching element control device including a phase shift means.

In constructing the switching element control device, instead of the electric signal detecting means, a current detecting means for detecting a current of the AC transmission line, a voltage detecting means for detecting a voltage of the AC transmission line, and a current detecting means. An impedance calculating means for calculating the impedance of the AC transmission line from the detected current of the means and the detected voltage of the voltage detecting means is provided, and instead of the command value generating means, the deviation between the impedance command value and the calculated value of the impedance calculating means is set. According to the calculation of the ignition phase angle for the switching element, a command value generating means for generating a command value of the control angle according to the calculation result is provided, and further, instead of the reference pulse signal generating means,
Reference pulse signal generation means for dividing the output pulse signal of the voltage controlled oscillation means to generate a reference pulse signal may be provided.

The following elements can be added when constructing each of the series compensation devices or switching element control devices.

(1) In response to a failure detection output of the failure detection means, when a preset time has elapsed, an accident start timer means for instructing the control voltage selection means to switch the control voltage selection. Be prepared.

(2) Accident elimination for instructing the control voltage selection means to switch the selection of the control voltage when a set time has elapsed after the generation of the failure detection output from the failure detection means is stopped. A post-start timer means is provided.

According to the above-mentioned means, at the time of system failure, the reference pulse signal is generated based on the control voltage generated before the system failure occurs, and the generated ignition pulse according to the reference pulse signal. Since the signal is given to the switching element, the operation of the switching element can be appropriately performed at the time of system failure and at the time of failure removal, and the recovery from the system accident can be speeded up.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a series compensation device showing an embodiment of the present invention. In FIG. 1, three-phase (U-phase, V-phase, W-phase) AC power transmission lines 14, 16, 18 that connect to the AC power systems 10, 12 are respectively connected to the power transmission lines 14, 16,
18 impedances (reactors 20u, 20v, 2
Series capacitors Cu, Cv, and Cw are respectively inserted in series in order to compensate (cancel) impedances represented by 0w, 22u, 22v, and 22w. AC reactors Lu, Lv, Lw are connected to the series capacitors Cu, Cv, Cw by thyristors Thu, Thx, Th.
They are connected in parallel via v, Thy, Thw, and Thz. U-phase thyristors Thu, Thx, V-phase thyristors Thv, Thy, W-phase thyristors Thw, Thz
Are connected in anti-parallel with each other, and AC reactors Lu, Lv,
Lw and series capacitors Cu, Cv, and Cw are connected respectively. And each thyristor Thu-Thz is constituted as a switching element which controls the phase of the electric current which flows through each reactor Lu, Lv, Lw in response to the ignition pulse signal from the control device 24, and series capacitors Cu, Cv, Cw, AC reactor Lu, Lv, L
It is configured as a thyristor-controlled series capacitor together with w.

The AC power transmission lines 14, 16, 18 detect the current of the AC power transmission lines 14, 16, 18 as an electric signal detecting means for detecting the electric signals of the AC power transmission lines 14, 16, 18. AC current detector 2 as current detection means
6u, 26v, 26w are provided, and AC voltage detectors 28u, 28v, 28 as voltage detecting means for detecting the voltages of the AC power transmission lines 14, 16, 18 respectively.
w, 28u ', 28v', 28w 'are AC power transmission lines 14, 1
6 and 18 are connected. And each AC current detector 2
Outputs of 6u to 26w and AC voltage detectors 28u to 28w 'are input to the control device 24, respectively.

As shown in FIG. 2, the control unit 24 includes impedance detection circuits 30u, 30v, 30w, a failure detection circuit 32, impedance control circuits 34u, 34v, 3 and 3.
4w, a switching circuit 36, a sync signal detection circuit 38, a sync signal creation circuit 40, and a pulse phase shift circuit 42.

The impedance detection circuit 30u is configured as impedance detection means for detecting the impedance of the transmission line 14 from the detection voltage ΔVu of the AC voltage detectors 28u and 28u 'and the detection current Iu of the AC current detector 26u, The impedance detection circuit 30v is configured as impedance detection means for detecting the impedance of the AC transmission line 16 from the detection voltage ΔVv of the AC voltage detectors 28v and 28v ′ and the detection current Iv of the AC current detector 26v. Also, impedance detection circuit 30w
Is the detection voltage ΔVw of the AC voltage detectors 28w and 28w ′.
And the detection current Iw of the AC current detector 26w, the impedance detection means for detecting the impedance of the AC transmission line 18. The detected values of the impedance detection circuits 30u to 30w are input to the impedance control circuits 34u to 34w, respectively, and the AC voltage detection values Vu, Vv, Vw and the AC current detection values Iu, I are detected.
v and Iw are input to the failure detection circuit 32, respectively. The failure detection circuit 32 detects the AC voltage detection values Vu and V.
The detection output (detection signal) Fd is synchronized with the detection output (detection signal) Fd, which is configured to detect an accident such as a ground fault or a short circuit in the power system from v, Vw and the AC current detection values Iu, Iv, Iw. Signal generation circuit 40, pulse phase shift circuit 42
Has been entered in.

Impedance control circuits 34u, 34v,
34w calculates the ignition phase angle (β) for each thyristor Thu to Thz according to the deviation between the impedance command value Zp and the detected value of each impedance detection circuit 30u, 30v, 30w, and according to this calculation result. It is configured as command value generation means for generating command values (αu, αx, αv, αy, αw, αz) of the control angle. That is,
The impedance control circuits 34u, 34v, 34w are configured to perform a process for converting the firing phase angle β into a control angle (control delay angle) α. Specifically, the firing phase angle β of 0 ° corresponds to the control angle α of 180 °, and when actually firing each thyristor, the control angle α = 0 ° is set as the synchronization reference point. Since it is necessary to set the firing timing, the firing phase angle β is converted into the control angle α. In this case, there is 1 between the firing phase angle β and the control angle α.
Since there is a difference of 80 degrees, the control angle α = π−β is calculated to calculate the control angle α, and the calculated control angle α is output as a command value. The command values output from the impedance control circuits 34u to 34w are input to the pulse phase shift circuit 42 via the switching circuit 36. The switching circuit 36 operates in accordance with the output pulse of the pulse phase shift circuit 42 to control the impedance control circuits 34u to 34u.
The command value output from w is sequentially switched and output to the pulse phase shift circuit 42. The pulse phase shift circuit 42 includes a reference pulse signal S generated based on the sync pulse signal Sn detected by the sync signal detection circuit 38.
s has been entered.

The synchronizing signal detection circuit 38 detects the alternating current detected value I detected by the alternating current detectors 26u to 26w.
u, Iv, and Iw are taken in, and the synchronization pulse signal Sn is configured as a synchronization pulse signal generation unit that detects a synchronization point (zero cross point) that is a zero point of each current and generates a synchronization pulse signal Sn. It is input to the creating circuit 40.

As shown in FIG. 3, the synchronizing signal generating circuit 40 includes a phase difference detecting circuit 44, an operational amplifier circuit 46, a bias power source 48, an adding circuit 50, a switching circuit 52, a phase memory circuit 54, and a voltage controlled oscillator circuit 56. , And a frequency dividing circuit (decoder) 58.

As shown in FIG. 4, the phase difference detection circuit 44 detects the phase difference Δθ between the sync pulse signal Sn output by the sync signal detection circuit 38 and the reference pulse signal Ss output by the frequency divider circuit 58. A signal of the detected phase difference Δθ is output to the operational amplifier circuit 46. The operational amplifier circuit 46 controls and amplifies the phase difference Δθ, amplifies the phase difference Δθ, and outputs a control voltage Ec corresponding to the phase difference Δθ. That is, the phase difference detection circuit 44 and the operational amplification circuit 46 are configured as control voltage generation means. The control voltage Ec output from the operational amplifier circuit 46 is added to the bias voltage from the bias power source 48 in the adder circuit 50, and the added voltage is input to the switching circuit 52 and the phase storage circuit 54.

The switching circuit 52 is the failure detection circuit 3
Before the failure detection signal Fd is input from 2, the control voltage Ec from the adder 50 is selected, and when the failure detection signal Fd is input, the control voltage Ec ′ stored in the phase storage circuit 54 is selected, The selected control voltage is output to the voltage controlled oscillator circuit 56 as a command value. The phase memory circuit 54 controls the control voltage Ec by the output of the adder circuit 54.
Is stored as a voltage related to the phase difference Δθ for, for example, 10 ms, and this voltage is held as a control voltage Ec ′. Further, when the failure detection signal Fd is input, the value of the control voltage Ec ′ stored before the system failure occurs is held until the failure detection signal Fd is released.

The control voltage oscillation circuit 56 changes its oscillation frequency in response to the control voltage selected by the switching circuit (control voltage selection means) 52, specifically in proportion to the average value of the control voltage Ec or Ec '. However, the voltage control oscillating means is configured to output a pulse signal corresponding to the oscillation frequency, and the pulse signal is input to the frequency dividing circuit 58. The frequency dividing circuit 58 divides the output pulse signal of the voltage controlled oscillator circuit 56 into a pulse signal having a frequency six times the commercial frequency, and divides the divided pulse signal into the reference pulse signal Ss.
It is configured as a reference pulse signal generating means for outputting as. That is, in order to generate the reference pulse signals for the six thyristors Thu to Thz, the frequency oscillating at a high frequency is divided up to 6 times the commercial frequency to generate the reference pulse signal Ss. .

The synchronizing signal generating circuit 40 is configured as a PLL (phase locked loop) circuit, and is a deviation (phase difference) between the synchronizing pulse signal Sn and the reference pulse signal Ss.
When Δθ is subjected to the first-order advance / delay control in the operational amplifier circuit 46, the operational amplifier circuit 46 outputs the control voltage Ec as shown in FIG. 4, and the control voltage oscillation circuit 56 outputs
A pulse signal having an oscillation frequency corresponding to the average voltage of the control voltage Ec is output, and this pulse signal is divided by the frequency dividing circuit 58 into a frequency that is six times the commercial frequency, whereby the reference pulse signal for each thyristor is obtained. Is generated.

Here, the frequency of the system rises and the current Iu
Assuming that the zero point has advanced, the phase of the synchronization pulse signal Sn advances, so the phase difference Δθ due to the output of the phase difference detection circuit 44 increases and the output Ec of the operational amplifier circuit 46 also increases. Therefore, the oscillation frequency of the voltage controlled oscillator circuit 56 becomes high, and the phase of the reference pulse signal Ss produced by the output of the frequency divider circuit 58 also advances. In this way, the control that follows the frequency of the system is performed.

On the other hand, when the frequency of the system drops,
Since the phase of the synchronization pulse signal Sn is delayed, the phase difference Δθ due to the output of the phase difference detection circuit 44 becomes small and the output Ec of the operational amplifier circuit 46 also becomes small. Therefore, the oscillation frequency of the voltage controlled oscillator circuit 56 becomes low, and the phase of the reference pulse signal Ss due to the output of the frequency divider circuit 58 is also delayed. In this way, the control that follows the frequency of the system is performed.
That is, the synchronization signal generating circuit 40 operates so that the reference pulse signal Ss output from the frequency dividing circuit 58 always follows with a phase difference between the zero point of the system current and a certain point.

The phase difference in the steady state is calculated by the operational amplifier circuit 4
6 can be arbitrarily set by changing the bias voltage applied to the output Ec. That is, by arbitrarily adjusting the output voltage of the bias power source 48, the oscillation frequency can be made to coincide with the zero-degree point or the 180-degree point of the phase of the voltage across each of the series capacitors Cu to Cw.

On the other hand, the pulse phase shift circuit 42 shown in FIG.
It is configured as pulse phase shifting means for shifting the reference pulse signal Ss according to the command value input from the switching circuit 36 to generate an ignition pulse signal and outputting this ignition pulse signal to each of the thyristors Thu to Thz. .

Specifically, as shown in FIG. 5, the firing pulse signals of the thyristors Thu to Thz of each phase are U⇒Z⇒V.
⇒ X ⇒ W ⇒ Y, that is, thyristors Thu, T
π / 6 in the order of hz, Thv, Thx, Thw, and Thy.
Each one is late. For example, in the case of the U phase, the Ssu point is the generation timing of the reference pulse signal Ss generated by the synchronization signal generating circuit 40, that is, the phase of the voltage across the series capacitor Cu of the U phase is 0 degree (command value α = 0 degree). At the point, the command value generated by the impedance control circuit 34u is αu
At the time of, in response to the reference pulse signal Ssu, the command value αu
The pulse Pu shifted only by this is output from the pulse phase shift circuit 42 as an ignition pulse signal for the thyristor Thu. When the ignition pulse signal Pu is output, the switching circuit 36 switches the output signal, and the impedance control circuit 34w outputs the command value αz. As a result, the pulse phase shift circuit 42 switches to the next reference pulse signal Ssz delayed by π / 6, and the reference pulse signal Ssz
Is output as a firing pulse signal Pz to the thyristor Thz. When this firing pulse Pz is output, the pulse phase shift circuit 42 outputs π / from the reference pulse signal Ssz as the next pulse.
The pulse signal is switched to the reference pulse signal Ssv delayed by 6 and the pulse signal obtained by shifting the reference pulse signal Ssv by the command value αv is output to the thyristor Thv as the ignition pulse signal Pv. Similarly, the reference pulse signals Ssx, Ss
The firing pulse signals Px, Pw, Py obtained by shifting w, Ssy by the command values αx, αw, αy are sequentially output to the thyristors Thx, Thw, Thy at a timing delayed by π / 6.

When the ignition pulse signal is generated by the pulse phase shift circuit 42, when a system fault occurs, the reference pulse signal generated based on the control voltage Ec 'stored in the phase storage circuit 54 before the fault is used. Therefore, since the ignition pulse is generated, the ignition pulse signal can be generated in the same manner as before the accident even in the event of an accident, and each thyristor can be continuously operated.

In the above configuration, when the impedance of each transmission line 14, 16, 18 is compensated by using the series compensator, the ignition phase angle for operating in the capacitive impedance region is obtained during steady operation, and the system At the time of the accident, in order to suppress the overvoltage generated in the series capacitors Cu to Cw, a process of obtaining an ignition phase angle for fully operating each thyristor to operate in the capacitive impedance region is performed. In this case, as shown in FIG. 6, the firing phase angle β is determined depending on whether the impedance command value Zp input to the control device 24 indicates the capacitive impedance Zc or the inductive impedance Zl.

FIG. 6 is a diagram showing the impedance characteristics with respect to the firing phase angle of each thyristor on the horizontal axis. The positive region shows the capacitive impedance and the negative region shows the inductive impedance. The angle taken in the direction of 180 ° to 0 ° as the phase of the voltage across the series capacitor is represented by the firing phase angle β. When β = 0 °, the reactors Lu to L
Since no current flows in w, the impedance of the series compensator is the same as the impedance of the series capacitors Cu to Cw Zc0 = 1 / ωC (ω = 2πf: commercial frequency)
Is. As the value of the firing phase angle β of the thyristor is increased, the current flowing through the reactors Lu to Lw increases, and the impedance increases due to the capacitance up to the firing phase angle of βlim. βlim represents an ignition phase angle at which the series capacitor and the AC reactor resonate at a commercial frequency. At an ignition phase angle exceeding this value, the current flowing in the reactors Lu to Lw becomes larger than the current flowing in the series capacitors Cu to Cw. , The impedance of the series compensator becomes an inductive impedance. Furthermore, as the firing phase angle β increases, the inductive impedance decreases, and β =
At 90 degrees, each thyristor becomes fully conductive. The impedance at this time is the parallel impedance of the AC reactor and the series capacitor, that is, the inductive impedance Z10. The impedance with respect to the firing phase angle β is described in the document “Kato et al., 6 persons,“ Study on control method of thyristor controlled series capacitor and development of reduced model ”, IEEJ Transactions B, Vol, 117, No. 7
(July 1997) ", it is obtained from the ratio of the fundamental voltage and the fundamental current of the transmission line by the following equation.

Impedance Xtcsc = πωL / (π
ω2LC-2β + sin2β) By adjusting the ignition phase angle β in this way, the impedance can be adjusted in the range from the capacitive region to the inductive region.

As shown in FIG. 4, when the firing angle of each thyristor is controlled by the capacitive impedance, the voltage Vu across the series capacitor Cu lags behind the detection current Iu by about 90 degrees.

When a three-phase ground fault occurs at the timing t = t0 shown in FIG. 4 when the thyristors are controlled in such a state, the fault detection circuit 32 detects an overcurrent and the fault occurs in the system. Is generated, the timing t
= T1, control is performed to fully conduct each thyristor, and each series capacitor is protected. At this time, the synchronization signal detection circuit 38 cannot detect the zero point of the normal current due to the accident current, and the operation of the phase difference detection circuit 44 is not normal. Therefore, the phase difference detection circuit 44 does not output a signal indicating a normal phase difference.

However, in the present embodiment, when a failure occurs in the system, the switching circuit 52 selects the control voltage Ec ′ stored in the phase storage circuit 54, so that the voltage controlled oscillator circuit 56 is controlled by the timing. t
After t1, the pulse having the oscillation frequency according to the control voltage Ec ′ stored in the phase storage circuit 54 is output, and the oscillation frequency is maintained at the oscillation frequency before the accident. Therefore,
Even during an accident, as in the case before the accident, the ignition pulse signal is generated according to the reference pulse signal Ss, and each thyristor can be continuously operated.

Further, even during an accident, each thyristor is controlled based on the reference pulse signal before the accident, because the system apart from the accident point operates based on the movement of the generator regardless of the accident. Since the operation of the thyristor also matches the situation of the accident,
This is because the grid can be quickly recovered from the accident by adjusting to the movement of the grid and the movement of the generator before the accident.

As described above, according to the present embodiment, the thyristor can be stably operated during the accident and after the accident is removed, thereby speeding up the recovery of the system after the accident is removed, thereby improving the system stability. Can be made.

The timing at which the switching circuit 52 switches from the selection of the control voltage Ec 'stored in the phase storage circuit 54 to the selection of the control voltage Ec by the output of the adder circuit 50, that is, the reset timing, is the failure detection circuit 32. It is possible to use the accident removal detection signal or the reset signal related to the accident detection signal Fd by the output. In this case, it is also possible to use the accident occurrence start timer means shown in FIG. 7A or the accident elimination start timer means shown in FIG. 7B.

The timer means shown in FIG. 7A is a timer 6
0 and a flip-flop 62, and the output signal of the failure detection circuit 32 is input to the set terminals of the timer 60 and the flip-flop 62. The timer 60 responds to the failure detection signal Fd output from the failure detection circuit 32 and resets the flip-flop 62 when a set time elapses after the failure detection signal Fd is input. The flip-flop 62 is set in response to the failure detection signal Fd of the failure detection circuit 32, and the failure detection signal Fd
d is output. Then, when reset by a signal from the timer 60, the switching circuit 52 is instructed to switch the selection of the control voltage. That is, the switching circuit 52 switches from the control voltage Ec ′ output from the phase storage circuit 54 to the selection of the control voltage Ec output from the adder circuit 50 when the failure detection signal Fd is not input from the flip-flop 62. . In addition, the set time of the timer 60, for example, the time from the accident detection to the accident removal,
It can be set to 3 cycles.

FIG. 7 (b) takes into account the delay in returning to the normal state after the accident is removed in the case of a major accident.
It is configured by including an inverter 64, a timer 66, and a flip-flop 62. The inverter 64 inverts the level of the output signal of the failure detection circuit 32 and inputs the inverted signal to the timer 66. The timer 66 is started on the condition that the generation of the high-level failure detection signal Fd from the failure detection circuit 32 is stopped, that is, when the output level of the inverter 64 is inverted by the elimination of the accident,
After that, when the set time elapses, flip flip 6
It is supposed to reset 2. Thus, by using such timer means, it is possible to instruct the switching circuit 52 to switch after the accident is eliminated.

In the above embodiment, the case of controlling the impedance of the power transmission line has been described. However, instead of the impedance command value, a current command value, a voltage command value, a power command value or another command value may be used. The present invention can also be applied to a control system using other command values, only the command value and the detected value serving as a feedback signal differ.

[0043]

As described above, according to the present invention,
At the time of a system failure, a reference pulse signal is generated based on the control voltage generated before the system failure occurs, and the generated ignition pulse signal according to this reference pulse signal is given to the switching element. The operation of the switching element at the time of failure and at the time of failure removal can be appropriately performed, and recovery from a system fault can be accelerated.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a series compensation device showing an embodiment of the present invention.

FIG. 2 is a block configuration diagram of a control device.

FIG. 3 is a block configuration diagram of a synchronization signal generation circuit.

FIG. 4 is a waveform diagram for explaining the operation of the synchronization signal generation circuit.

FIG. 5 is a waveform diagram for explaining the operation of the pulse phase shift circuit.

FIG. 6 is a characteristic diagram showing a relationship between a firing phase angle and impedance.

FIG. 7 is a diagram for explaining a configuration of a start-up timer means when an accident occurs and a start-up timer means after an accident is removed.

[Explanation of symbols]

Cu, Cv, Cw Series capacitors Lu, Lv, Lw AC reactors Thu, Thx, Thv, Thy, Thw, Thz thyristors 10, 12 AC systems 14, 16, 18 AC power transmission lines 20u, 20v, 20w, 22u, 22v, 22w AC reactor 24 Control devices 26u, 26v, 26w AC current detectors 28u, 28v, 28w, 28u ', 28v', 28w '
AC voltage detector 30u, 30v, 30w Impedance detection circuit 32 Failure detection circuit 34u, 34v, 34w Impedance control circuit 36 Switching circuit 38 Synchronous signal detection circuit 40 Synchronous signal generation circuit 42 Pulse phase shift circuit 44 Phase difference detection circuit 46 Operational amplification Circuit 50 Adder circuit 52 Switching circuit 54 Phase memory circuit 56 Voltage controlled oscillator circuit 58 Frequency divider circuit

Front page continued (72) Inventor Shigeyuki Sugimoto 20-1 Kitakaseyama, Otaka-cho, Midori-ku, Nagoya-shi, Aichi Chubu Electric Power Co., Inc. Electric Power Technology Research Institute 20-1 Kitakanyama, Otaka-machi, Chuo Electric Power Co., Ltd., Technology Development Center, Chubu Electric Power Co., Inc. (56) References Tokuhei 8-500718 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02J 3/00-5/00

Claims (8)

(57) [Claims] 1. A series capacitor inserted in series with an AC power transmission line, an AC reactor connected in parallel with the series capacitor, and a series capacitor connected in series with the AC reactor in response to an ignition pulse signal to drive the AC reactor. A switching element for controlling the phase of a flowing current, an electric signal detecting means for detecting an electric signal of the AC transmission line, and an ignition for the switching element according to a deviation between a command value and a detected value of the electric signal detecting means. Command value generating means for calculating the phase angle and generating a command value for the control angle according to the calculation result,
Failure detection means for detecting a failure of the AC system based on the electric signal of the AC transmission line, and synchronization pulse signal generation means for generating a synchronization pulse signal synchronized with the electric signal in response to the electric signal of the AC transmission line. A control voltage generating means for generating a control voltage according to the phase difference between the reference pulse signal and the synchronizing pulse signal, and a failure of the AC system due to the failure detecting means among the control voltages generated by the control voltage generating means. A control voltage storage means for storing the control voltage generated before being detected, and a control voltage stored in the control voltage storage means in response to the failure detection output of the failure detection means, and otherwise selected Control voltage selecting means for selecting the control voltage generated by the control voltage generating means, and a pulse signal having an oscillation frequency corresponding to the control voltage selected by the control voltage selecting means. Voltage control oscillating means, a reference pulse signal generating means for generating a reference pulse signal according to an output pulse signal of the voltage controlling oscillating means, and a reference pulse signal generating means for generating a command value generated by the command value generating means. And a pulse phase shifting means for generating a firing pulse signal and outputting the firing pulse signal to the switching element. 2. A series capacitor inserted in series with an AC power transmission line, an AC reactor connected in parallel with the series capacitor, and a series capacitor connected in series with the AC reactor in response to an ignition pulse signal. A switching element that controls the phase of the flowing current, a current detection unit that detects the current of the AC transmission line, a voltage detection unit that detects the voltage of the AC transmission line, a detection current of the current detection unit, and the voltage detection. Impedance calculation means for calculating the impedance of the AC transmission line from the detected voltage of the means, and the ignition phase angle for the switching element is calculated according to the deviation between the impedance command value and the calculated value of the impedance calculation means. A command value generating means for generating a command value of the control angle according to the result, and an alternating current based on the electric signal of the alternating current transmission line. Fault detection means for detecting a system fault, sync pulse signal generation means for generating a sync pulse signal in synchronization with the electric signal of the AC transmission line, and a reference pulse signal and the sync pulse signal Control voltage generation means for generating a control voltage according to the phase difference of,
Control voltage storage means for storing the control voltage generated before the failure of the AC system is detected by the failure detection means among the control voltages generated by the control voltage generation means, and the failure detection output of the failure detection means. In response, the control voltage stored in the control voltage storage means is selected, and otherwise the control voltage generated by the control voltage generation means is selected, and the control voltage selection means selects the control voltage. A voltage control oscillating means for outputting a pulse signal having an oscillating frequency according to the control voltage, a reference pulse signal generating means for dividing the output pulse signal of the voltage controlling oscillating means to generate a reference pulse signal, and the command value generation The reference pulse signal generated by the reference pulse signal generating means is shifted in accordance with the command value generated by the means to generate an ignition pulse signal. Series compensator comprising a pulse phase shifting means for outputting a signal to the switching element. 3. An accident occurrence start-up timer means for instructing the control voltage selection means to switch the selection of the control voltage when a set time has elapsed in response to the failure detection output of the failure detection means. The series compensator according to claim 1 or 2, wherein 4. After elimination of an accident, the control voltage selection means is instructed to switch the selection of the control voltage when a set time has elapsed after the generation of the failure detection output from the failure detection means is stopped. The series compensator according to claim 1 or 2, further comprising a start-up timer means. 5. An electric signal detection means for detecting an electric signal of an AC power transmission line, and a deviation between a command value of an ignition phase angle for a switching element inserted in the AC power transmission line and a detection value of the electric signal detection means. Command value generating means for generating a control angle command value according to the calculation result, failure detecting means for detecting a failure of the AC system based on an electric signal of the AC transmission line, and the AC transmission Synchronous pulse signal generating means for generating a synchronous pulse signal synchronized with the electric signal in response to the electric signal of the electric wire, and control voltage generation for generating a control voltage according to the phase difference between the reference pulse signal and the synchronous pulse signal. Means, control voltage storage means for storing a control voltage generated before the failure of the AC system is detected by the failure detection means among the control voltages generated by the control voltage generation means, and the failure. Control voltage selecting means for selecting the control voltage stored in the control voltage storing means in response to the failure detection output of the detecting means, and selecting the control voltage generated by the control voltage generating means in other cases, and this control A voltage control oscillating means for outputting a pulse signal having an oscillation frequency corresponding to the control voltage selected by the voltage selecting means, a reference pulse signal generating means for generating a reference pulse signal according to the output pulse signal of the voltage controlling oscillating means, Pulse phase shifting means for shifting the reference pulse signal generated by the reference pulse signal generating means in accordance with the command value generated by the command value generating means to generate an ignition pulse signal and outputting the ignition pulse signal to the switching element. A switching element control device provided. 6. The current detection means for detecting the current of the AC power transmission line, the voltage detection means for detecting the voltage of the AC power transmission line, the detection current of the current detection means and the detection voltage of the voltage detection means. Impedance calculation means for calculating the impedance of the AC transmission line, and the ignition phase angle for the switching element inserted in the AC transmission line is calculated according to the deviation between the impedance command value and the calculated value of the impedance calculation means. Command value generation means for generating a command value of the control angle according to the result, failure detection means for detecting a failure of the AC system based on the electric signal of the AC power transmission line, and response to the electric signal of the AC power transmission line. Sync pulse signal generating means for generating a sync pulse signal synchronized with the lever electrical signal, and a control voltage according to the phase difference between the reference pulse signal and the sync pulse signal. Control voltage generating means for generating,
Control voltage storage means for storing the control voltage generated before the failure of the AC system is detected by the failure detection means among the control voltages generated by the control voltage generation means, and the failure detection output of the failure detection means. In response, the control voltage stored in the control voltage storage means is selected, and otherwise the control voltage generated by the control voltage generation means is selected, and the control voltage selection means selects the control voltage. A voltage control oscillating means for outputting a pulse signal having an oscillating frequency according to the control voltage, a reference pulse signal generating means for dividing the output pulse signal of the voltage controlling oscillating means to generate a reference pulse signal, and the command value generation The reference pulse signal generated by the reference pulse signal generating means is shifted in accordance with the command value generated by the means to generate an ignition pulse signal. Switching element control device comprising a pulse phase shifting means for outputting a signal to the switching element. 7. An accident occurrence start timer means for instructing the control voltage selection means to switch the selection of the control voltage when a set time has elapsed in response to the failure detection output of the failure detection means. 7. The switching element control device according to claim 5, wherein: 8. After the accident elimination, instructing the control voltage selection means to switch the selection of the control voltage when a set time has elapsed after the generation of the failure detection output from the failure detection means is stopped. 7. The switching element control device according to claim 5, further comprising a startup timer means.