JP3533516B2 - Series Compensator and Series Compensation System for Power System - 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 series compensation system for a power system, and more particularly, it is suitable for compensating the impedance of an AC transmission line by a series capacitor and an AC reactor inserted in the AC transmission line. The present invention relates to a series compensation device and a series compensation system of a power system.

[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 applied in Northern Europe, North America and South America, where there are many long-distance transmission lines.

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, it depends on L (inductance) of the transmission line or generator and C (capacity) of the series compensation device. The electric resonance frequency approaches the commercial frequency, and the 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 US Electric Power Research Institute (EPRI), and its application in an actual system is under consideration.

On the other hand, in Japan, cooperation among electric power companies is being promoted due to environmental problems and improvement in reliability of power transmission. But,
If the wide area linkage is simply performed, the short-circuit capacity increases in the event of an accident due to the increase in the AC system. Therefore, when performing wide area coordination, the short-circuit current is 63 kA.
In consideration of the fact that if the voltage exceeds the limit, the circuit breaker cannot interrupt the current due to the generation of an arc, and it is considered to put a reactor in the AC transmission line to limit the current. However, if the reactor is simply inserted in the AC transmission line, the impedance increases, and the stability of the system deteriorates.

As a countermeasure against this, a control method using a thyristor-controlled series capacitor has been proposed. As a control method of this kind, for example, as described in Japanese Patent Laid-Open No. 9-74682, a series capacitor is inserted in series with an AC transmission line and an AC reactor and a pair of thyristors are connected in parallel with the series capacitor. However, when the system is normal, in order to improve stability, more current is passed through the series capacitor than in the AC reactor to operate in the capacitive impedance region to cancel out the inductive impedance of the transmission line. There is a method in which a large amount of current is supplied to the AC reactor to operate in the inductive impedance region to suppress the fault current.

[0006]

However, in the prior art, the method of operating the thyristor in the inductive impedance region at the time of system failure is adopted. However, the thyristor has a firing phase angle (control advance angle) of 90 degrees. It only ignites and fully conducts the thyristor, and does not sufficiently consider the effective use of the inductive impedance region according to the contents of the system failure. That is, when the thyristor is operated in the inductive impedance region, an angle in the range smaller than 90 degrees can be used as the ignition phase angle with respect to the thyristor.

On the other hand, when the thyristor is operated in the range of the ignition phase angle of 0 ° to 90 °, one region becomes the capacitive impedance region and the other region becomes the inductive impedance region at a certain ignition phase angle. , When the thyristor is ignited at a control angle corresponding to the ignition phase angle that is the boundary between the two regions, the series capacitor and the AC reactor resonate with the commercial frequency. Therefore, when operating the thyristor, it is necessary to set the ignition phase angle in consideration of the state of the system.

An object of the present invention is to provide a series compensator, a series compensation system for a power system, and a series compensation method for a power system, which can always compensate the system impedance in a stable state regardless of the state of the AC system. Especially.

[0009]

In order to achieve the above object, the present invention provides a series capacitor inserted in series in an AC 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, a current detection unit that detects a current of the AC transmission line, and a voltage of the AC transmission line. Voltage detecting means, impedance calculating means for calculating the impedance of the AC transmission line from the detected current of the current detecting means and the detected voltage of the voltage detecting means, a capacitive impedance command value and a calculated value of the impedance calculating means. The ignition phase angle for the switching element is calculated according to the deviation from the Signal for generating a signal to output to the switching element, the ignition phase angle for the switching element according to the deviation between the inductive impedance command value and the calculated value of the impedance calculating means. And a capacitive ignition pulse signal generating means for generating an ignition pulse signal having a control angle according to the calculation result and outputting the ignition pulse signal to the switching element. The ignition pulse signal generating means is a limit having a margin between the boundary between the capacitive impedance region and the inductive impedance region of the impedance characteristic showing the relationship between the impedance of the capacitor and the AC reactor and the ignition phase angle. Constituting a series compensator in which the calculated values of the ignition phase angle are limited according to the values A.

In constructing the series compensator,
The capacitive ignition pulse signal generating means and the induction ignition pulse signal generating means are ignited according to a limit value having a margin between the capacitor and the ignition phase angle when the AC reactor resonates at the frequency of the AC transmission line. It can be configured by limiting the calculated values of the phase angle.

In constructing each of the series compensators, the following elements can be added.

(1) The inductive firing pulse signal generating means generates a firing pulse signal having a wider pulse width than the firing pulse signal generated by the capacitive firing pulse signal generating means.

(2) A positive sign is added to the capacitive impedance command value to output to the capacitive ignition pulse signal generating means, and a negative sign is added to the inductive impedance command value to cause the induction. Impedance firing command signal output means for outputting to the capacitive ignition pulse signal generation means, wherein the impedance calculation means adds a plus sign to the capacitive impedance of the calculated impedances to generate the capacitive ignition pulse signal generation means. And adds a minus sign to the inductive impedance and outputs it to the inductive ignition pulse signal generating means.

(3) A synchronization reference for taking in an electric signal from the AC transmission line and detecting a first synchronization reference point synchronized with the electric signal and a second synchronization reference point having a phase different from that of the first synchronization reference point. Point detecting means, and the capacitive firing pulse signal generating means selects the first synchronization reference point as a reference point for a control angle of the capacitive firing pulse signal in response to the capacitive impedance command value. The inductive ignition pulse signal generating means is responsive to the inductive impedance command value, and is the second reference point for the control angle of the inductive ignition pulse signal. Inductive reference point selecting means for selecting a synchronization reference point is provided.

Further, the present invention constitutes a series compensation system for a power system, comprising any one of the series compensation devices described above and a current limiting reactor inserted in series with a series capacitor of an AC transmission line. .

Further, according to the present invention, a series capacitor and a current limiting reactor are respectively inserted in series with an AC transmission line, an AC reactor is connected in parallel with the series capacitor, and the AC reactor is connected in response to an ignition pulse signal. A switching element that controls the phase of a flowing current is inserted between the series capacitor and the AC reactor, wherein a capacitive impedance command value is generated during normal operation of the AC transmission line, and the AC transmission line. The impedance of the AC transmission line is calculated by detecting the electric signal of the capacitor, and the firing phase angle for the switching element is calculated according to the deviation between the capacitive impedance command value and the calculated impedance value, and the capacitor And the ignition position when the AC reactor resonates at the frequency of the AC transmission line An ignition pulse of a control angle according to the calculation result of the ignition phase angle limited to the limit value or less by limiting the calculated value of the ignition phase angle with a limit value having a margin between the angle and the maximum value. A signal is generated and output to the switching element, an inductive impedance command value is generated when the AC power transmission line is abnormal, and an electrical signal of the AC power transmission line is detected to calculate the impedance of the AC power transmission line. When the ignition phase angle with respect to the switching element is calculated according to the deviation between the inductive impedance command value and the calculated impedance value, and the capacitor and the AC reactor resonate at the frequency of the AC transmission line. The calculated value of the ignition phase angle is limited to a limit value having a margin between the ignition phase angle and Is obtained by employing the series compensation method for a power system, characterized in that to produce a firing pulse signal points of the control angle in accordance with the calculation result of limited ignition phase angle is output to the switching element.

According to the above-mentioned means, when calculating the ignition phase angle for generating the ignition pulse signal, the capacitive impedance of the impedance characteristic showing the relationship between the impedance of the capacitor and the AC reactor and the ignition phase angle. Limit the calculated value of the ignition phase angle according to the limit value that has a margin between the region and the boundary of the inductive impedance region, or the ignition phase when the capacitor and the AC reactor resonate at the frequency of the AC transmission line. Since the calculated value of the ignition phase angle is limited according to the limit value that has a margin with the angle, when operating the switching element in the capacitive impedance region or the inductive impedance region, the The arc phase angle can be limited to a certain range to keep the switching element operating stably. Rukoto together is possible, it is possible to compensate for the impedance of the system in accordance with the state of the system.

[0018]

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, a series capacitor C is inserted in series in an AC transmission line 100 of an AC system (electric power system), and an AC reactor L is connected in parallel with the series capacitor C via thyristors 10 and 12. There is. The thyristors 10 and 12 are connected in antiparallel with each other and are connected to the AC reactor L and the series capacitor C, respectively. Each of the thyristors 10 and 12 is configured as a switching element that controls the phase of the current flowing through the AC reactor L in response to the firing pulse signal from the control device 14. In addition, in the AC power transmission line 100,
An AC current transformer 16 serving as a current detection unit that detects a current of the AC power transmission line 100 is provided, and an AC voltage transformer 18 serving as a voltage detection unit that detects a voltage of the AC power transmission line 100 is provided. It is connected to the. The detected current of the AC current transformer 16 and the detected voltage of the AC voltage transformer 18 are input to the control device 14, respectively.

The control device 14 is provided with an impedance detection circuit 20, etc., as shown in FIG. 2, in order to detect the actual impedance of the AC power transmission line 100. The impedance detection circuit 20 serves as an impedance calculation means, and outputs a current I from the AC current transformer 16.
ac and the voltage Vac from the AC voltage transformer 18 are taken in, the impedance Zf of the AC transmission line 100 is calculated from the input current and voltage, and a positive sign is added to the capacitive impedance of the calculated impedance. The negative impedance is added to the inductive impedance for output.

Further, the control unit 14 generates an ignition pulse signal for each of the thyristors 10 and 12 based on the impedance detected by the impedance detection circuit 20 and the impedance command value Zp, as shown in FIG. Value switching circuit 22, capacitive impedance control circuit 24, inductive impedance control circuit 26, output switching circuit 28, β / α conversion circuit 30, phase control circuit 32.
It is configured with.

The impedance command value switching circuit 22 receives the impedance command value Zp and the command value Zsw as the impedance command value output means, and outputs the impedance command value to which the plus sign is added as the capacitive impedance command value. However, as the inductive impedance command value, the impedance command value to which a minus sign is added is output. That is, when a capacitive impedance command value is output with respect to the impedance command value Zp, a plus sign is added to the impedance command value Zp according to the command value Zsw to which a plus sign is added, and the capacitive impedance control circuit is added. Two
4 to output the inductive impedance command value, a negative sign is added to the impedance command value Zp according to the command value Zsw to which the negative sign is added to the impedance command value Zp. It is adapted to output to the control circuit 26.

The capacitive impedance control circuit 24 includes an output switching circuit 28, a β / α conversion circuit 30, and a phase control circuit 3.
2 is configured as a capacitive ignition pulse signal generating means, and specifically, as shown in FIG.
4, capacitive impedance control arithmetic circuit 36, Zc / β
The conversion circuit 38 is provided. The adder 34 receives the capacitive impedance command value Zcp to which a plus sign is added from the impedance command value switching circuit 22, and the impedance detection circuit 20.
From, the calculated impedance Zcf is input. A positive sign is added to the impedance Zcf for the capacitive impedance, and a negative sign is added for the inductive impedance. The adder 34 outputs a signal corresponding to the deviation between the capacitive impedance command value Zcp and the calculated impedance Zcf to the capacitive impedance control arithmetic circuit 36. The control calculation circuit 36 calculates the impedance Zc by performing a proportional integration calculation for making the deviation between the signal from the adder 34, that is, the capacitive impedance command value Zcp and the calculated impedance Zcf zero.
The calculation result is output to the Zc / β conversion circuit 38. The Zc / β conversion circuit 38 is the control arithmetic circuit 36.
The impedance Zc obtained by the above calculation is converted into the ignition phase angle β and output. In this case, in the present embodiment, the Zc / β conversion circuit 38 uses the phase firing angle β
Is generated, the function is provided as a limiter for limiting the ignition phase angle β within a certain range.

Specifically, as shown in FIG. 5, the firing phase angle (control advance angle) β with respect to the thyristors 10 and 12 can be set in the range of 0 to 90 degrees, but β = 0 degrees ( When the control angle is 180 degrees), the thyristors 10 and 12
In the non-conducting state, no current flows in the AC reactor L, so that the impedance is Zc0 = 1 / ωC (ω = 2πf, f: commercial frequency), which is the same as the impedance of the series capacitor C. On the other hand, as the value of the ignition phase angle β increases, the current flowing through the thyristors 10 and 12 increases and the current flowing through the AC reactor L also increases.
When the firing phase angle β becomes βlim, the capacitive impedance becomes infinite. Where the firing phase angle β is βli
When it is set to m, the series capacitor C and the AC reactor L resonate at the commercial frequency. Further, if the value of the ignition phase angle β is made larger than βlim, the current flowing through the AC reactor L becomes larger than the current flowing through the series capacitor, and the impedance becomes the inductive impedance Zl.

Therefore, when operating the thyristors 10 and 12 with the capacitive impedance, a point showing the boundary between the capacitive impedance region and the inductive impedance region in the impedance characteristic showing the relationship between the ignition phase angle β and the impedance. The limit value (βlim-Δβc) having a margin with respect to the arc phase angle βlim is set as the maximum value to limit the value of the ignition phase angle β. That is, in the capacitive impedance region, the thyristors 10 and 12
Value of the ignition phase angle β from 0 to (βl
It is set within the range of im-Δβc). Note that Δβc is set to 10 degrees, for example.

On the other hand, the inductive impedance control circuit 26
Is configured as an inductive ignition pulse signal generation means together with the output switching circuit 28, the β / α conversion circuit 30, and the phase control circuit 32. Specifically, as shown in FIG. Impedance control arithmetic circuit 42, Zl
The / β conversion circuit 44 is provided.

The adder 40 receives an inductive impedance command value (-Zl from the impedance command value switching circuit 22).
p) is input, and the impedance Zlf to which a negative sign is added is also input from the impedance detection circuit 20. The adder 40 outputs a signal according to the deviation between the inductive impedance command value (-Zlp) and the detected impedance Zlf to the inductive impedance control arithmetic circuit 42. The control calculation circuit 42 performs a proportional integration calculation to make the deviation between the signal from the adder 40, that is, the inductive impedance command value (-Zlp) and the detected impedance Zlf zero, and performs the inductive impedance Zl. Is calculated and the calculated value is output to the zl / β conversion circuit 44. The Zl / β conversion circuit 44 converts the input inductive impedance Zl into the ignition phase angle β and outputs the same, and also converts the inductive impedance Zl into the ignition phase angle β in the present embodiment. It has a function as a limiter for limiting the value of the arc phase angle β to a certain fixed range.

Specifically, as shown in FIG. 5, when the value of the ignition phase angle β is set between β lim and 90 degrees, the thyristors 10 and 12 can be operated in the inductive impedance region, and β When the thyristors 10 and 12 are operated at = 90 degrees, the thyristors 10 and 12 are in full conduction,
Impedance is AC reactor L and series capacitor C
Is the parallel impedance value of. That is, the impedance Z10 is inductive.

However, when the value of the ignition phase angle β is set to βlim, the series capacitor C and the AC reactor L resonate at the commercial frequency. Therefore, in the present embodiment, the firing phase angle (βlim + Δβ) that is a limit value having a margin between the firing phase angle βlim that indicates the boundary between the capacitive impedance region and the inductive impedance region.
l) as the minimum value, the ignition phase angle β is (βlim + Δβ
l) to 90 degrees. Note that Δβl is set to 10 degrees, for example.

Further, the impedance with respect to the ignition phase angle β is described in the literature "" Study on control method of thyristor controlled series capacitor and development of reduced model ", IEEJ Transactions B,
Vol. 117, No. 7 ",
It can be calculated by the following formula from the values of the fundamental wave voltage and the fundamental wave current of the transmission line.

Xtcsc = πωL / (πω2LC-2β
+ Sin2β) Firing phase angle β obtained by the capacitive impedance control circuit 24 and the inductive impedance control circuit 26 shown in FIG.
The signals relating to each are input to the output circuit 28. In the output switching circuit 28, one of the firing phase angles β is selected according to the command value Zsw, and the β / α conversion circuit 3 is selected.
It is designed to output to 0. That is, the output switching circuit 28 outputs the firing phase angle β from the capacitive impedance control circuit 24 when the capacitive impedance is commanded.
Is selected and when the inductive impedance is commanded, the firing phase angle β from the inductive impedance control circuit 26
Is to be selected.

The β / α conversion circuit 30 is configured to convert the input ignition phase angle β into a control angle (control delay angle) α. That is, 0 degree of the ignition phase angle β corresponds to 180 degree of the control angle α, and the thyristor 1
When actually firing 0 and 12, it is necessary to set the firing timing with the control angle α = 0 degree as the synchronization reference point. Therefore, a process for converting the firing phase angle β into the control angle α is required. To do. In this case, since there is a difference of 180 degrees between the firing phase angle β and the control angle α, the control angle α is calculated by calculating the control angle α = π−β, and the calculated control angle α is The signal is output to the phase control circuit 32.

The phase control circuit 32 is adapted to generate and output a capacitive firing pulse signal or an inductive firing pulse signal according to the control angle α. In this case, as shown in FIG. 7, the capacitive ignition pulse signal of the control angle αc is output at the timing with the first synchronization reference point t1 as a reference, and the control angle αl with the second synchronization reference point t2 as a reference. The inductive pulse signal of is to be output. Therefore, the phase control circuit 32 takes in a current signal as an electric signal from the AC power transmission line 100, obtains a voltage signal by integrating this current signal, and determines the 0 cross point of this voltage signal as the first synchronization reference point t1. And the first synchronization reference point t1 is 180
A built-in synchronization reference point detection circuit is provided as a synchronization reference point detection means for detecting points having different phase as the second synchronization reference point t2.

Further, the phase control circuit 32 uses the command value Zs.
In response to w, when the command value Zsw is positive, the first point is set as the reference point for the control angle αc of the capacitive ignition pulse signal.
Of the second synchronization reference as a reference point for the control angle αl of the inductive firing pulse signal when the command value Zsw is negative. It incorporates a selection circuit as inductive reference point selection means for selecting the point t2.

That is, as shown in FIG. 7A, the thyristors 10 and 1 are connected to the current i flowing through the power transmission line 100.
When 2 is operated in the capacitive impedance region, the voltage across series capacitor C lags current i by 90 degrees, and when thyristors 10 and 12 are operated in the inductive impedance region, the voltage across series capacitor C is current. 90 degrees ahead of i. That is, the voltage Vc across the capacitor C in the capacitive impedance region and the voltage Vl across the series capacitor C in the inductive impedance region are 180 degrees out of phase.

Therefore, in this embodiment, the command value Z
The synchronization reference point is switched by 180 degrees according to sw. Specifically, when operating in the capacitive impedance region, the control angle αc is set with reference to the synchronization reference point t1, and when operating in the inductive impedance region, the control angle αl is set with reference to the second reference point t2. I have decided. When operating the thyristors 10 and 12 in the capacitive impedance region, the control angle αc with respect to the first synchronization reference point t1 is set to the thyristor 10 as a reference.
The capacitive ignition pulse signal is given at the timing of, and the control angle αc with respect to the second synchronization reference point t2 is given to the thyristor 12.

On the other hand, when the thyristors 10 and 12 are operated in the inductive impedance region, the thyristor 10 is inductively fired at the timing of the set control angle αl based on the second synchronization reference point t2. A pulse signal is given to the thyristor 12 at the timing of the control angle α1 set with reference to the first synchronization reference point t1 which is 180 degrees out of phase with the second synchronization reference point t2. Will be given.

Further, when applying the ignition pulse signal to the thyristors 10 and 12, a time width of about 50 μs is set as a capacitive ignition pulse signal, for example, a pulse width sufficient to ignite the thyristors 10 and 12. When the narrow pulse signal is provided and the inductive ignition pulse signal is applied to the thyristors 10 and 12, from the ignition timing to the timing when the command value Zsw is switched, the thyristor 10,
A wide pulse signal for keeping 12 conductive is decided to be output. That is, when the thyristors 10 and 12 are ignited in the inductive impedance region, if the pulse width of the firing pulse signal is narrow, the thyristors 10 and 12 may become non-conducting after conducting.
The current flowing through 0 and 12 is intermittent, and the thyristors 10 and 12
May turn off and show no inductive impedance. Therefore, in the present embodiment, when the thyristors 10 and 12 are operated in the inductive impedance region, the inductive ignition pulse signal is continuously supplied to the thyristors 10 and 12 for the entire period in which the thyristors 10 and 12 should be in conduction, and the thyristor 10 is thereby supplied. , 12 can be stably operated even in the inductive impedance region by igniting all of the conductive periods.

In the above structure, when the AC transmission line is normal,
That is, when the AC power transmission line 100 is in a normal state,
A capacitive impedance command value is generated, the impedance command value is compared with the impedance of the system detected by the impedance detection circuit 20, and the firing phase angle β according to the deviation between the two is calculated. At this time, the ignition phase angle β is limited to the range of 0 to the limit value (βlim-Δβc). Thereafter, the control angle α according to the firing phase angle β limited to this limit value or less is obtained, and the firing pulse signal of the control angle α is generated to generate the control pulse α.
The control of sequentially firing 0 and 12 is performed. This causes the impedance of the power transmission line 100 to show a capacitive impedance.

On the other hand, when the system is abnormal, for example, the transmission line 10
When a short circuit accident or the like occurs at 0, an inductive impedance command value is generated along with the detection of the short circuit current, and the inductive impedance command value and the impedance detection circuit 2
The impedance of the system by the detection of 0 is compared, and the firing phase angle β is calculated according to the deviation between the two, and
The ignition phase angle β is limited to the range of 90 degrees from the limit value (βlim + Δβl). Then, a firing pulse signal having a control angle α1 according to a firing control angle β limited to a limit value or more is generated, and the thyristors 10 and 12 are sequentially fired according to the inductive firing pulse signal, and the transmission line An impedance of 100 will exhibit inductive impedance. Thereby, the current of the power transmission line 100 is limited by the inductive impedance, and the short-circuit current can be limited.

Next, the system configuration when the DC compensator according to the above embodiment is applied to a power system will be described with reference to FIG.

In the DC compensation system for the electric power system according to the present embodiment, a DC compensation device is provided on an AC transmission line 100 connecting one AC system 46 and the other AC system 48, and a line of the AC transmission line 100. A short-circuit current suppressing reactor 50 is inserted as a current limiting reactor in series with the series capacitor C.

In this embodiment, when the system is normal, the thyristors 10 and 12 are controlled to operate in the capacitive impedance region, and when the system is abnormal, for example, when a short circuit occurs, the thyristors 10 and 12 are inductive impedance. Control for operating in the area is performed. In this case, the short-circuit current can be limited by the reactor 50 and the AC reactor L, and the short-circuit current can be interrupted by the circuit breaker when the short-circuit current is limited. After that, when the system returns to the normal state, the system can be operated in a stable state by operating the thyristors 10 and 12 again in the capacitive impedance region.

[0043]

As described above, according to the present invention,
When calculating the ignition phase angle for generating the ignition pulse signal, the boundary between the capacitive impedance area and the inductive impedance area of the impedance characteristic showing the relationship between the impedance of the capacitor and the AC reactor and the ignition phase angle is calculated. Limit value that has a margin between the ignition phase angle when the capacitor and the AC reactor resonate at the frequency of the AC transmission line. Since the calculated value of the ignition phase angle is limited in accordance with the above, when the switching element is operated in the capacitive impedance region or the inductive impedance region, the ignition phase angle is limited to a certain range regardless of the system state. It is possible to always operate the switching element stably, It is possible to compensate for the impedance of the system in accordance with the state.

[Brief description of drawings]

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

FIG. 2 is a block configuration diagram of an impedance detection circuit.

FIG. 3 is a block configuration diagram of a control device.

FIG. 4 is a block diagram of a capacitive impedance control circuit.

FIG. 5 is an impedance characteristic diagram showing a relationship between a firing phase angle and impedance.

FIG. 6 is a block configuration diagram of an inductive impedance control circuit.

FIG. 7 is a waveform diagram for explaining the operation of the device shown in FIG.

FIG. 8 is a block diagram illustrating a configuration of a DC compensation system of a power system.

[Explanation of symbols]

C series capacitor L AC reactor 10, 12 thyristor 14 Control device 16 AC current transformer 18 AC voltage transformer 20 Impedance detection circuit 22 Impedance command value switching circuit 24 Capacitive impedance control circuit 26 Inductive impedance control circuit 28 Output switching circuit 30 β / α conversion circuit 32 phase control circuit 34 adder 36 Capacitive impedance control arithmetic circuit 38 Zc / β conversion circuit 40 adder 42 Inductive impedance control arithmetic circuit 44 Zl / β conversion circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeyuki Sugimoto 20-1 Kitakanyama, Otaka-cho, Midori-ku, Nagoya-shi, Aichi Chubu Electric Power Co., Inc. Electric Power Technology Research Laboratory (72) Inventor Yuji Yamazaki Midori, Nagoya-shi, Aichi 20-1 Kitakanyama, Otaka-machi, Chuo Electric Power Research Laboratory, Chubu Electric Power Co., Inc. (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02J 3/00-5/00

Claims (7)

(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 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 calculating means for calculating the impedance of the AC transmission line from the detected voltage of the means, and calculating the firing phase angle for the switching element according to the deviation between the capacitive impedance command value and the calculated value of the impedance calculating means Capacitive to generate a firing pulse signal with a control angle according to the calculation result and output it to the switching element A firing pulse signal generating means, a firing phase angle for the switching element is calculated according to a deviation between an inductive impedance command value and a calculated value of the impedance calculating means, and a control angle is fired according to the calculation result. An inductive ignition pulse signal generating means for generating a pulse signal and outputting the pulse signal to the switching element, wherein the capacitive ignition pulse signal generating means and the inductive ignition pulse signal generating means are the capacitor and the alternating current. The calculated value of the firing phase angle is respectively limited according to the limit value having a margin between the capacitive impedance region and the boundary of the inductive impedance region of the impedance characteristic showing the relationship between the impedance of the reactor and the firing phase angle. Series compensation device. 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 calculating means for calculating the impedance of the AC transmission line from the detected voltage of the means, and calculating the firing phase angle for the switching element according to the deviation between the capacitive impedance command value and the calculated value of the impedance calculating means Capacitive to generate a firing pulse signal with a control angle according to the calculation result and output it to the switching element A firing pulse signal generating means, a firing phase angle for the switching element is calculated according to a deviation between an inductive impedance command value and a calculated value of the impedance calculating means, and a control angle is fired according to the calculation result. An inductive ignition pulse signal generating means for generating a pulse signal and outputting the pulse signal to the switching element, wherein the capacitive ignition pulse signal generating means and the inductive ignition pulse signal generating means are the capacitor and the alternating current. A series compensator configured to limit the calculated value of the firing phase angle according to a limit value having a margin between the reactor and the firing phase angle when resonating at the frequency of the AC transmission line. 3. The inductive firing pulse signal generation means comprises:
3. The series compensator according to claim 1, wherein an ignition pulse signal having a wider pulse width than the ignition pulse signal generated by the capacitive ignition pulse signal generating means is generated. 4. The capacitive impedance command value is added with a plus sign and is output to the capacitive firing pulse signal generating means, and the inductive impedance command value is added with a minus sign. Impedance command value output means for outputting to the ignition pulse signal generating means is provided, and the impedance calculating means adds a plus sign to the capacitive impedance of the calculated impedances to cause the capacitive ignition pulse signal generating means. The series compensator according to claim 1, 2 or 3, wherein the series impedance is output, and a negative sign is added to the inductive impedance to output to the inductive ignition pulse signal generating means. 5. A synchronization reference check for taking in an electrical signal from the AC transmission line and detecting a first synchronization reference point synchronized with the electrical signal and a second synchronization reference point having a phase different from that of the first synchronization reference point. Output means, and the capacitive firing pulse signal generation means selects the first synchronization reference point as a reference point for the control angle of the capacitive firing pulse signal in response to the capacitive impedance command value. Capacitive reference point selection means is provided, and the inductive ignition pulse signal generation means is responsive to the inductive impedance command value, and the second synchronization is used as a reference point for a control angle of the inductive ignition pulse signal. 5. The series compensation device according to claim 1, further comprising inductive reference point selecting means for selecting a reference point. 6. A series compensation system for a power system, comprising: the series compensator according to claim 1, 2, 3, 4 or 5, and a current limiting reactor inserted in series with a series capacitor in the AC transmission line. . 7. A phase of a current flowing through the AC reactor in response to an ignition pulse signal, wherein a series capacitor and a current limiting reactor are respectively inserted in series with the AC transmission line, and the AC reactor is connected in parallel with the series capacitor. In which the switching element for controlling is inserted between the series capacitor and the AC reactor, a capacitive impedance command value is generated when the AC transmission line is normal, and an electrical signal of the AC transmission line is generated. The impedance of the AC transmission line is detected and calculated, and the ignition phase angle for the switching element is calculated according to the deviation between the capacitive impedance command value and the impedance calculated value, and the capacitor and the AC reactor are also calculated. And the ignition phase angle when they resonate at the frequency of the AC transmission line. Limit the calculated value of the ignition phase angle with a limit value having a maximum value, and generate the ignition pulse signal of the control angle according to the calculation result of the ignition phase angle limited to the limit value or less. It outputs to the switching element, and generates an inductive impedance command value when the AC power transmission line is abnormal, and calculates an impedance of the AC power transmission line by detecting an electrical signal of the AC power transmission line. The ignition phase angle for the switching element is calculated according to the deviation between the impedance command value and the impedance calculation value, and the ignition phase angle when the capacitor and the AC reactor resonate at the frequency of the AC transmission line. Limit the calculated value of the firing phase angle by setting a minimum limit value having a margin between Series compensation method for a power system, characterized in that to produce a firing pulse signal points of the control angle in accordance with the calculation result of the phase angle is output to the switching element.