JPS6152721A - Control method of static reactive power compensating device - Google Patents

Abstract

PURPOSE:To obtain the suppressing effect even for the voltage variance of a small disturbance by monitoring a controlled variable and increasing the angle of the gradient of the characteristic of a static reactive power compensating device to lead the controlled variable into a constant voltage control region when it reaches the terminal of the constant voltage control region. CONSTITUTION:A system voltage is detected by a voltage transformer 2 and a rectifying circuit 42 and is compared with the voltage of a reference circuit 43, and the current flowed to a compensating reactor 5 and a compensating capacitor 6 is detected to output a voltage through a slope gain circuit 51, and this voltage and said differential voltage are added. Thyristors 7 and 8 are controlled by a transmission function circuit 46, a Q-alpha function generating circuit 47, and an igniting pulse generating circuit 48 to hold down the system voltage within a constant voltage control region A-B. When the controlled variable approaches a point A or B, this approach is detected by a gamma limit detecting circuit 415 or an alpha limit detecting circuit 414, and the slope gain circuit 51 is controlled to increase the gradient [from (a) to (b)], and the control point is approximated to the center.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a first method of a static adaptive power compensator that is connected to a power grid and maintains grid voltage stability.

[Technical background of gi'i' 1 and its highlights] In order to suppress voltage fluctuations in the power system, it is necessary to control reactive power, which is the largest cause of voltage fluctuations. For this reason, voltage fluctuations are generally suppressed by using a static reactive power compensator to supply an advanced reactive power needle that is approximately equal to the delayed reactive power of the load.

FIG. 3 shows a single line diagram and a control block diagram of a conventional static var power compensator. In □□□, 1 is a power system, 2 is a voltage transformer, 3 is a current transformer, 4 is a control device for the stationary non-active power compensation↓゛ device, 5 is a compensation reactor, 6
is a compensation capacitor, 7 and 8 are thyristors, 41 Fi
M flow circuit, 42-digit low-pass filter, 43 is voltage base 1
44 and 45 are addition points, 46 is a transfer function circuit, 4
Reference numeral 7 denotes a Q-α relation ξ generation circuit, 48 an ignition pulse generation circuit, 49 a rectifier circuit, 50 a low-pass filter, and 51 a slope gain circuit 18.

Next, the operation will be explained. The crushed earth type reactive power compensator stabilizes the grid voltage by supplying phase leading reactive power or lagging reactive power to the power grid. The voltage transformer 2 detects the system voltage, and this voltage is converted into a DC TEEE with small ripple by the rectifier circuit 41 and the low-pass filter 42.
Convert. In addition, the output from the power n calculation point 44 low-pass filter and the output from the voltage reference circuit 13 are input,
Let's compare. The voltage signal from the low-pass filter 42 is the base signal from the reference IL pressure circuit 43. i1.
When it is lower than V7, it is a static invalid 1; the force compensator supplies phase-advanced reactive power, but when it is higher than V7, it is a static invalid 1.
The output of the summing point 44 is passed through the summing point 45, and the voltage is maintained at or near the reference voltage. several times;I
'11611 is input. In the transfer function circuit 46, the circuit configuration is determined by the +d ratio crushing circuit etc.
1. Ru. Transmission amount: The output of the attack circuit 46 is input to the Q-α function generation circuit 4'7. Here the phase of thyristor 7.8: li! The invalid force characteristic Q, which is determined by the I leg (control delay angle α), approximates the c function. Q-α function generation circuit 4
The output of thyristors 7 and 8 is inputted to an ignition pulse generation circuit 48, where it is generated by a circuit that generates gate pulses to be applied to thyristors 7 and 8. Further, the current flowing through the compensation reactor 5 and the compensation capacitor 6 is detected by the current transformer 3 and input to the rectifier circuit 49. The output of the rectifier circuit 49 is input to a low-pass filter 50, which suppresses ripples in the same manner as the low-pass filter 42. The output of the low-pass filter 50 passes through the entire slope gain circuit 51 and is input to the addition point 45. This slope gain circuit 51 will be explained later using FIG.

In this way, the static reactive power compensator operates l/'c so as to suppress the deviation of the system voltage from the reference voltage.

Furthermore, the operation of voltage control will be explained using FIG. This diagram (a) shows the control characteristics of the static var power compensator.

In Fig. 4 1al, the compensation reactor 5 is opened by the thyristors 7 and 8 between O and A, and only the compensation capacitor 6 is connected, and the area where the phase-advanced reactive current changes in proportion to the voltage is A-8. Between B and 0, the constant pressure characteristics are maintained by the control of thyristors 7 and 8, and between B and 0, when the current of compensation reactor 5 is maximized by thyristors 7 and 8YC, the current is proportional to the voltage. In the region where the slow phase reactive current changes.

The slope between A-8 is exceeded by the gain of the slope gain circuit 51, and is selected so that 100% of the static var power compensator capacity can be controlled with a voltage fluctuation of about 1 to 5 el. v. The point is the reference point of the grid voltage. Fourth
The characteristic equation between A and -8 in Figure (al) is I = Kt (V
-Vo ) .=-(1), the slope of this characteristic is given by 1/1. Kl is the system voltage V and the reference voltage V. (set value), that is, the amount that determines how many times the output of the static reactive force compensator should be multiplied by the amount of change from the set value. Therefore, d34 [A of 1(a)]
The characteristic between -8 is gain! (The larger the value of 1 is, the smaller the magnitude is and the characteristic is close to horizontal. The smaller the gain is, the larger the slope is.) Next, when a static static type var compensator with such static characteristics is connected to the grid, When the system is simplified to ft) and expressed as shown in FIG. 4 (1), the rIf pressure-current characteristic of the system is expressed by equation (2).

V = Eo-Z -I , , , , -(2
1. If this characteristic and the characteristic of the static var compensator are combined together, the result is shown in FIG. 4(c), and the response to fluctuations in the system voltage can be understood. In Fig. 4(c), the power supply voltage E0
The response of the static var compensator when the value fluctuates is as follows. The power supply voltage is now B. Assume that when , the terminal voltage of the static type reactive force compensator is Vo and the output is zero. From this state, the system voltage increases to +ΔE.

When this changes, the voltage/current characteristics of the system become V=(Eo+ΔEo)−Z−I, and the intersection with the voltage/undercurrent characteristics of the static var power compensator moves to the right. Therefore, the static reactive power compensator uses a lagging current 11 corresponding to the intersection with the voltage-current characteristics of the grid.
As a result, the terminal voltage of the static var compensator is lowered to V. If there is no static reactive power compensator, the terminal voltage is E, +ΔE0, so E0 + ΔE
This means that the voltage is suppressed by 0-V. Conversely, when the system voltage changes by -ΔEo, the voltage-current characteristic of the system becomes V=(Bo-ΔE0)-Z·min, and the intersection with the voltage-current characteristic of the static var power compensator moves to the left. As a result, the static var compensator outputs a delayed current (2) to the intersection point, and as a result, the current is raised to V2. Since the 1" voltage when there is no device for static passive power compensation fl' is E6 - ΔEo, V2
This means that the voltage is suppressed by (Eo - ΔEo).

By the way, the grid voltage changes rapidly, and the voltage-current characteristics of the grid become V-, 3, which does not intersect with the line A-B in Fig. 4(a).
'? j, combination is shown in FIG. 4(d). In this figure, the system's negative pressure characteristics (a) will break when the voltage increases, and (b) will break when the voltage drops. In this case, the static form is invalid η1′
, force reinforcement and resistance are located at the end of phase control called α limit in characteristic (a) of the system voltage, and at the end of phase control called gamma limit in characteristic (b). In any of these cases, the voltage is outside the constant voltage control region.

As described above, it has been found that in the conventional control method, when the system voltage characteristics do not intersect between A and B, the ability to control the voltage is completely lost.

[Purpose of the invention]

The object of the present invention was made in view of the above points, and
If it is out of the constant voltage control area, it will be pulled into the constant voltage control area and the constant voltage 1 will be applied.
It is an object of the present invention to provide a control method for a static reactive force compensator capable of recovering the 1ill+ capability.

[Summary of the invention]

The present invention monitors the control amount of the static var power compensator, and when it reaches the end of the constant voltage control region, increases the slope angle of the characteristic of the static var power compensator and draws it into the constant voltage control region. , it is designed to exert a suppressing effect even on voltage fluctuations caused by small disturbances.

[Embodiments of the invention]

An embodiment of the present invention will be described below.

FIG. 1 is a single line diagram and a control block diagram of a static var power compensator for explaining the control method of the present invention. The same numbers as in FIG. 3 indicate the same parts, 414 is an α limit detection circuit, 415 is a γ limit detection circuit, 4
16 is an OR circuit, 417 is a changeover switch circuit, 418
is detected by the level detection circuit. 1 In FIG. 1, the system voltage is converted into a low voltage signal by voltage transformation circuit 2, and a current signal voltage is generated by a rectifier circuit 41 and a filter 42. Voltage reference circuit 43
, the addition points 44, 44, and the transfer function circuit are similar to those described in FIG.

In the α limit detection circuit 414 and r limit detection circuit 415, the output value from the continuous function circuit 46 is controlled by constant voltage control.
The youngest of the 11 regions; determines whether it is at M (limit), and if it reaches the end, it passes through the logical sum circuit 416 and the changeover switch circuit 417 to the slope gain circuit 5.
1 and operates to increase the slope gain. The slope gain circuit 51 is statically disabled when the output value of the transfer function circuit 46 reaches the end of the open/open region. , force h
The slope of the voltage-current characteristic of the zero compensation device is increased. In this way, things that are out of the control area will be pulled into the control area.

・Also, the level detection circuit 418 monitors whether the system 1a pressure has recovered to a value close to the voltage reference value, and when it has recovered, the changeover switch circuit 417 is switched to change the slope gain of the slope gain circuit 51 to the original value. VC operates to restore the state. This will be explained using FIG. The characteristic shown in Figure 2 (a) is an example of the characteristic of the conventional system, and the limit is where it intersects with the grid characteristic, so it has no suppressing effect on voltage fluctuations below the limit. The characteristic (b) is based on the present invention and shows the case where the slope gain is increased. It can be seen that this brings the voltage into the constant voltage control region and exerts the effect of suppressing voltage fluctuations.

Figure 2 (a) shows the second case when the grid voltage is in the rising direction.
Figure fb) shows the case where the trend is in the downward direction.

〔Effect of the invention〕

As shown above, according to the present invention, even if the grid voltage changes greatly and reaches the limit of the constant voltage control region, the control slope cannot be changed, the grid voltage will change greatly, and even a small disturbance voltage fluctuation will occur. The control ability can be improved even if the control ability continues.

[Brief explanation of the drawing]

Fig. 1 is a four-line connection diagram and control jtl block diagram of the static static type var power compensator of the present invention, Fig. 2 is a voltage-current characteristic diagram for explaining the present invention, and Fig. 3 is a conventional static static type var power compensator. A single line diagram and a control block diagram of the static var power compensator, and FIG. 4 is a control characteristic diagram of the static var power compensator. 1..., ij, j power system 2...'id pressure transformer 3
...Current transformer 1...Stationary non-active power sleeve 131 device split part II device [)...Doosan Ij′i Ributor 6...1 City 11 Correct/De/S 7
．． 8... Thyristor 41.49... Rectifier circuit 42.50... Low pass filter 43... Voltage reference circuit 51... Slope gain circuit 4.4.45...
1aII calculation point 16...Transfer function circuit lt7...Q-α generation circuit 48...Ignition pulse generation circuit 114...α limit detection circuit 415...r limit detection circuit 416... OR circuit 417... Changeover switch circuit 418... Level detection circuit (7317) Agent Futo Physician Noriyuki Chika (Ni,
or 1 person) Figure 4 (α9 Figure 4 (b)

Claims (1)

[Claims] In a static reactive power compensator, a compensation reactor and a compensation capacitor are provided in parallel between the power system and the load in order to stabilize the system voltage, and the phase of the current flowing through the compensation reactor is controlled by a thyristor. and when the controlled amount reaches the limit of the control region of the static var power compensator, the static var power compensator is pulled into the control region by adjusting the control slope of the voltage-current characteristic of the static var power compensator. A method of controlling a static var power compensator characterized by: