JPS62152027A - Voltage control system - Google Patents

Abstract

PURPOSE:To accurately set and control the received voltage at a set reference voltage level by using a reactive power adjusting device to increase or decrease smoothly the lagging reactive power. CONSTITUTION:A comparison arithmetic unit 10 compares the voltage V1 given from a transformer PT of a lagging reactive power adjusting device 6 with the reference voltage V0 to be set and outputs an error V=V1-V0. While a controller 11 receives the input of the output error voltage V from the unit 10 and gives the ON/OFF control to those switches Sw1-Swn, Sw1'-Swn', S1-Sn, S1'-Sn' and S0 so that the electric signal V is equal to 0. At the same time, the controller 11 drives the rotor of the controller 6 via a driver 12 to control it. Then the control is carried out to apply the reactive power when the error voltage V given from the unit 10 is plus. While the leading reactive power is applied when the voltage V is minus. Thus the error voltage become zero.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a voltage control method for controlling received voltage by adjusting reactive power.

BACKGROUND OF THE INVENTION Systems for controlling received voltage by regulating and compensating reactive power are known in the art. These devices use synchronous phase modifiers, reactors and capacitors, or thyristors to adjust the delayed reactive power and control the voltage. As a result, the starting device is multi-faceted, requiring time and effort for maintenance and inspection, and has the disadvantages of being loud. Further, the method using a reactor and a capacitor has the disadvantage that smooth adjustment of reactive power cannot be performed and the changeover switch is worn out. That is, since the reactor adjusts the reactive power by changing the number of turns of the winding by switching the tap, the reactive power is adjusted stepwise by this tap switching, and smooth voltage control is not possible.

Furthermore, since reactive power is adjusted by changing the number of capacitors that are turned on and off, voltage adjustment becomes stepwise.

Furthermore, the delayed reactive power adjustment method using a thyristor uses a thyristor to control the current flowing through the reactor, so it is possible to smoothly adjust the voltage, but it has the disadvantage that harmonics are generated, which adversely affects the power supply.

On the other hand, the applicant has proposed a reactive power adjusting device that improves the drawbacks of the conventional reactive power adjusting device and uses a phase shifter consisting of a rotor and a stator, and a transformer (Japanese Patent Application No. 60-189).
No. 692).

Problems to be Solved by the Invention The present invention improves the drawbacks of the above-mentioned prior art and solves the above-mentioned 1.
It is an object of the present invention to provide a voltage control method that can smoothly control the received power voltage and requires almost no maintenance by using the reactive power adjustment device proposed in the second proposal.

Means for Solving the Problems The first invention connects a plurality of reactors to a power source in parallel through a first switch, and includes a phase shifter and a transformer consisting of a rotor and a stator. The rotor and stator of the phase shifter are each wound with a winding, and the terminals of the windings wound around the wire-wound rotor are connected to the secondary terminal of the transformer, and the rotation A primary side terminal of the transformer, a terminal of a winding wound around the stator, and Capacitors are connected in parallel to the terminals of each of the reactors through the respective second switches, and the voltage a and the set reference voltage are compared, and the voltage is adjusted according to the difference between them. Voltage control is performed by controlling the second switch and the rotating means to adjust delayed reactive power.

Further, the second invention further provides a method in which a plurality of capacitors are connected to a power source in parallel with the plurality of reactors, each via a first switch, and a terminal of each capacitor is connected to a power supply in parallel with the plurality of reactors.
Connect to the primary side terminal of the transformer connected in parallel through the switch and the terminal of the winding wound around the stator, compare the power supply voltage and the set reference voltage, and calculate the difference. Accordingly, the first and second switches and rotating means are controlled to adjust lead and lag reactive power and perform voltage control.

Effect In the first invention, the first invention. Open all the second switches, set the rotation angle of the rotor of the phase shifter to 0 degrees, then turn any of the second switches ONL, and then turn the second switch corresponding to the above second switch. By turning on the first switch, then increasing the rotation angle of the rotor, adjusting the rotation angle to 180 degrees in electrical angle, and then turning off the second 1; The delayed reactive power can be clearly increased.

In addition, when reducing delayed reactive power, start from a state where all the first switches are ON and all the second switches are OFF, first, set the rotation angle of the rotor to 180 degrees, and then Turn on any second switch and set the rotor to zero.
At the same time, adjust the gl, then set the first 1-11 switch corresponding to the second switch turned ON above to O, F F, and then
By also turning off the second open 1NA device, the delayed reactive power can be gradually reduced.

In addition, in the second invention, in addition to the delayed reactive power control performed in the first invention, the ON and OFF of the first and second switches of the capacitor are controlled, and the rotation angle of the rotor is controlled. As a result, the lagging reactive power increases smoothly from the leading reactive power.

can be reduced.

Embodiment FIG. 1 shows the principle of an embodiment of a reactive power adjustment device used in the present invention, in which terminals A, B, and C of a phase shifter 3M and a three-phase transformer T are connected to a three-phase AC power supply A, B.

Connected to C.

The phase shifter M is composed of a wire-wound rotor 1 and a stator 2. A worm gear 4 is fixed to the rotor shaft 3 of the rotor 1, and an A-m 5 is meshed with the worm gear 4. By rotating the worm 5, the rotor 1 can be rotated, and the static IF position of the stator 2 can be controlled. The stator 2 is provided with a three-phase primary winding, its terminals Δ, B, and C are connected to a three-phase AC power supply, and the rotor 1 is provided with a three-phase secondary winding. The terminals a, b, and c are connected to the secondary terminals a, b, and c of the three-phase transformer T, and the primary terminals A, B, and C of the three-phase transformer T are connected to the three-phase AC power supply. A.

Connected to B and C. Note that the three-phase winding of the rotor 1 of the phase shifter M may be used as the primary winding, and the three-phase winding of the stator 2 may be used as the secondary winding. Further, in the above embodiment, the rotor 1 of the phase shifter M can be rotated with respect to the stator 2, but conversely, the stator 2 can be rotated with respect to the rotor 1. It's okay. Further, although the worm 5 and the A-me gear 4 are used as means for relatively rotating the rotor 1 or the stator 2, other configurations may be used.

Therefore, in this embodiment having the above configuration, the rotor 1 of the phase shifter M is rotated relative to the worm 5 and stopped at a position rotated by an electrical angle θ, and the reactive power in this state is analyzed. do.

Let el be the voltage induced in the a phase of the three-phase winding of rotor 1,
Let e2 be the induced voltage on the secondary side a phase of the transformer T. Then, the transformation ratio of the transformer T is such that the absolute value of the voltage e1 induced in the a phase of the three-phase winding of the rotor 1 is equal to the absolute value of the induced voltage 62 in the a phase of the secondary side of the transformer T. Select as follows.

Now, if we take the above-mentioned induced voltage e2 as a reference and let e2=E, then the induced voltage d1 on the rotor winding side becomes e+=EεJO since the position of the rotor 1 has rotated by θ in electrical angle.

Let Z be the sum of the leakage impedances for one phase of the winding of rotor 1 and the secondary winding of transformer T, and let the resistance be r.
, the reactance is represented by x, then the current I flowing from the a-phase terminal of the three-phase winding of rotor 1 to the a-phase terminal of the secondary side of transformer T is expressed by the following equation (1). .

, e+-e2E6jO-EE E(6J'-1
> Therefore, assuming that the conjugate of current I is 1, reactive power QX due to reactance x is expressed by the following equation (2).

E(ε-θ-1) E(ε-jθ-1) Qx=xll=x-=□ r + jx r -jx εJθε-JO-εjθ-ε-JO+1= X F2・
□ r2+×2 2−(cosO+j sinθ) −(COSθ−j
sin θ) = × 139 ・r2+x' 2・(1-cos θ) = y, F2 ・---------r 2+x
2 F2 1 =□・□・2(1-cosθ) X (r/x)'2+i
・・・・・・(2) As can be seen from equation (2),
By changing the position θ of the rotor 1 of the phase shifter M, the reactive power Qx can be changed.

This relationship is illustrated in FIG. 2. Tsunawara,
If the position θ of the rotor 1 is plotted on the horizontal axis and the reactive power is plotted on the vertical axis, the reactive power due to the reactance X becomes a curve of Qx shown in the figure.

As can be seen from the QX curve in FIG.
By changing the position θ of the rotor 1 from 0 degrees to 180 degrees, it is possible to continuously avoid changing the delayed reactive power.

In the above explanation, only the A phase is considered, but the same applies to the B and C phases. Also, in the above explanation,
The reactive power due to the leakage reactance and excitation impedance of the stator 2 of the phase shifter M and the primary side of the transformer T is omitted, but this is to simplify the explanation, and the actual reactive power is It will be included.

Therefore, in the case of large and continuous adjustment of reactive power based on the principle described above, as shown in Fig. 3, r+ll
] of each bank of reactor L1. L2.

L3...in were connected in parallel to the power supply, and furthermore, the squeezed reactive power adjustment device 6 formed by the phase shifter M and the transformer T shown in Fig. 1 and the capacitor Co were connected in parallel. The switches S1' and S2'.

83'...N banks of reactors L+, L2 . L3...Connect in parallel to Ln.

Note that the reactor l+ of each of the n banks.

L2. The capacities of L3... and n are all equal, and the capacity of the delayed reactive power adjustment device 6 is made equal to the capacity of the reactor L1 of one bank. Furthermore, the capacitance R of the capacitor Co is made equal to the capacitance of the reactor L1 of one bank.

The case where the delayed reactive power is gradually increased from zero will be explained below.

Switch S1.82.83...Sn and switch S
1', 82', 83'-+++-8n' are all left at H'1, and the rotor 1 of the phase shift SM is set so that the delayed reactive power taken by the delayed reactive power adjustment device @6 becomes zero.
Adjust the rotation angle to 0 degrees, then turn on the switch 81',
Turn on the switch S1.

In this state, the delayed reactive power taken by the reactor L1 and the advanced reactive power taken by the capacitor Go are equal, and the delayed reactive power taken by the delayed reactive power adjustment device a6 is zero, so their total reactive power is zero. .

Next, the rotation angle of the rotor 1 of the phase shifter M is increased to adjust the rotation angle to 180 degrees (electrical angle) so that the delayed reactive power taken by the delayed reactive power adjustment device 6 becomes large. Next, when the switch 81' is opened, the reactive power taken from the power supply starts from zero, and the delayed reactive power is smoothly increased to the delayed reactive power taken by the reactor 1. In the same manner as above, reactor L2. L3...l-n are made to take the delayed reactive power in sequence.

Next, an adjustment method for reducing delayed reactive power will be described.

Switch S+, 32.83... Sn is all O
Also, the switches S1', S2', Ss'...
...When the delayed reactive power is gradually decreased from the state where all S ports are turned off, that is, the maximum delayed reactive power is taken from the power supply, first, the delay taken by the delayed reactive power adjustment device 6 is reduced. In order to increase the reactive power, the rotation angle of the rotor 1 of the phase shifter M is adjusted to 180 degrees, and the switch 81' is turned on.

Next, the rotation angle of the rotor 1 of the phase shifter M is adjusted to 0 degrees so that the delayed reactive power taken by the delayed reactive power adjusting device 6 becomes small, and the switch S1 is set to 0FFL, and then the switch 81'
is also turned off.

By doing the above, the delayed reactive power taken from the power supply is gradually reduced, and the delayed reactive power taken by the reactor L1 is reduced by the delayed reactive power valve.

Using the same procedure as above, reactor L2. L3...
What is necessary is to successively reduce the delayed reactive power taken by Ln. In this way, the capacity of the expensive phase shifter can be reduced to 1/2n of the maximum delayed reactive power amount.

Next, a method that can adjust from leading reactive power to lagging reactive power will be described.

Regarding the adjustment of advanced reactive power, please refer to the earlier patent application filed in 1986-
As stated in No. 189692, if a three-phase capacitor is connected in place of the reactor shown in FIG. Therefore, the sum of reactive power Q× composed of phase shifter M and transformer T (QX +Q
O) can shift the advanced reactive power curve by 1 sill, which is shifted downward in FIG. 2 by the amount of reactive power Qc, by the capacitor.

Therefore, by using the same method as shown in Fig. 3, in which the reactors are divided into multiple banks and connected, an arbitrary number n of capacitors can be connected in parallel with the reactive power adjustment device using the J reactor shown in Fig. 4. divided into banks of switch S
W+, SW2. SW3...Connect to the power supply via 3wn. Note that the capacitances of the capacitors 'tC1, C2°C3, . . ., Cn of each of the n banks are all made equal. Then, the delayed reactive power adjustment device 6 consisting of a phase shifter M and a transformer T is connected to switches SW+' and SW2'.
, SW3'...3wn' via r+ll
J's - each bank's capacitor "tc+, C2,
C3 . . . are connected in parallel to Cn, and the capacitance ω of the capacitor C1 of one bank is made equal to the capacitance of the delayed reactive power adjustment device 6.

Therefore, since the lagging reactive power adjustment using the reactor has already been described, the leading reactive power adjustment using the capacitor will be described. In this case, switches 81-3n in reactors L1-l-n.

81' to 3 n I and SO are all open, and first, a case will be described in which the progressive reactive power is gradually increased from zero. Switch SW+.

3w 2 , SW 3 +++++Sl n and switch SW+'.

SW2', SW3'...3wn' are all left open.

The rotation angle of the rotor 1 of the phase shifter M in FIG. 1 is adjusted to 180 degrees so that the reactive power adjustment device 6 obtains the maximum delayed reactive power.

Next, the switch SW+' in FIG. 4 is turned on, and then the switch SW+ is turned on. In this state, capacitor C+ (D takes leading reactive power and lagging reactive power adjusting device 6
Since the delayed reactive powers of are equal, their total reactive power is zero. Next, the rotation angle θ of the rotor 1 of the phase shifter M is decreased to bring the rotation angle θ to zero degrees so that the delayed reactive power taken by the delayed reactive power adjustment device 6 becomes small. Then, the switch SW1' is opened.

In this way, the advanced reactive power taken from the power supply starts from zero and progresses to the advanced reactive power taken by the capacitor C1, thereby smoothly increasing the reactive power. Thereafter, in the same manner, the capacitors C2, C3, . . . , Cn are used to collect reactive power.

The above has described the case where the advanced reactive power is gradually increased from zero, but conversely, when it is desired to decrease the advanced reactive power, the following operation is performed.

nil Opening of the country SW +, SW 2, Sw 3
...-8vtn are all turned on, and switches 3w1' and SW2' are turned on.

An operation that starts from a state where all 3w 3 '...5llll n' are open, that is, a state where the maximum forward reactive power is taken from the power supply, and proceeds from this state and gradually decreases the reactive power. Explain. First, the rotation angle θ of the rotor 1 of the phase shifter M is adjusted to zero degrees so that the delayed reactive power taken by the delayed reactive power adjustment device 6 becomes small. And between I! Turn on the fl switch SW+'. and,
Next, the rotation angle of the rotor 1 of the phase shifter M is increased to 180 degrees so that the delayed reactive power taken by the delayed reactive power adjusting device 6 becomes large. Then, SWl is opened. Then, S
Open W1'. By doing this, the reactive power gradually decreases after 0 points from the power supply, and the capacitor C1
This means that the amount of lead reactive power that was being consumed has been reduced.

Following the same procedure, capacitors C2, C3...
The advanced reactive power taken by Cn is reduced.

In this way, the advanced reactive power can also be adjusted, so if a capacitor-based reactive power regulator and an actuator-based reactive power regulator are used together, as shown in Figure 4, the advanced reactive power can be adjusted to a large extent. It can be adjusted from power to significantly delayed reactive power. In this way, the volume of the expensive phase shifter can be reduced to 1/2n of the maximum reactive power adjustment amount.

Therefore, one embodiment of the voltage control method at the receiving end of the present invention will be described using the above-described reactive power adjustment method.

FIG. 4 is a circuit diagram of an embodiment of the present invention, where PT is a transformer, and 10 is a transformer. The voltage V1 from the transformer PT is compared with the reference voltage Vo to be set, and the error V (=V1 Vo
), and 11 is a control device which receives the input of the output error voltage V from the comparison calculator 10 and controls each of the switches SW+ to Swn, S so that the electric signal V becomes O.
w+'~swn', S+-8n, Sz'~3n
l, S.

(In addition, So and Go are the capacitor C1 of one bank when using a capacitor and reactor as shown in Fig. 4.
-Cn, switches SW+' to 3wn', navy blue may be used. ), and controls the opening and closing of
The rotor 1 is rotated and controlled via a device 12,
When the error voltage (■) from the comparator 10 is positive, control is performed to take the delayed reactive power, and when the error voltage V is negative, the control is performed to take the leading reactive power so that the error voltage V becomes 0. It is something.

As shown in Figure 5, the voltage at the sending end is Vs.

Assume that the impedance of line l is (R + j The reactive power Q at the receiving end can be adjusted by the reactive power adjusting device of the present invention.

Assuming that the current flowing through the line l is It, this is expressed by the following equation (3).

Assume that the receiving end voltage is Vr =yrε-J6. Here, 6 is the phase difference angle of the voltage at the power transmitting and receiving end.

Using the above equation (3), the complex power at the receiving end is expressed as follows.

P-)j Q = W l 1vSvrε
-Jδ-Vr2 =□ (4) -jX Equation (4) can be rearranged to form the following equation (5).

(P+jQ) (R-jX) = VsWε-j6-
vr' (5) Since the real part and the imaginary part on both sides of equation (5) are equal, the following equation (6) holds true.

RP+XQ+Vr 2-Vr Vs cos 6RQ-
XP=−Vr Vs sin δ (6) When the sum of the squares of the two equations in equation (6) is taken, the following equation is obtained.

(RP+XQ+Vr')' + (RQ-XP)Q
=Vr 2Vs'-...-"
(7) Now, assume that the reactive power Q at the receiving end is increased to (Q+ΔQ) by the reactive power adjustment device of the present invention. If the fluctuation of the receiving end voltage in this case is ΔVr, it is expressed as the following equation.

ΔVr =, (6Vr / 8Q) ΔQ −・−(
8) By finding the partial differential (8Vr/8Q) from equation (7) and substituting it into equation (8), the following equation is obtained.

Z'Q + XVr2 Δvr=-□·ΔQ Vr (2XQ+2RP+2Vr'-VS 2) As can be seen from equation (9), the coefficient of ΔQ is negative. Therefore, if the reactive power at the receiving end is increased by ΔQ using the reactive power adjusting device of the invention, the receiving end voltage ■r will be reduced by Δ■r. Conversely, when the reactive power at the receiving end is reduced by the reactive power adjustment device of the present invention, the receiving end voltage Vr
becomes higher by ΔVr.

In this manner, the present invention can adjust the voltage at the receiving end by changing the position θ of the reactor, capacitor, and rotor.

Effects of the Invention As described above, the first invention provides a reactive power adjustment device that includes a reactor, a transformer, a rotor, a stator, and means for relatively rotating the rotor and stator. By smoothly increasing and decreasing the delayed reactive power, the received voltage can be accurately set and controlled to the set reference voltage.

In addition, the second invention adds a capacitor to the first invention to clearly control the delayed reactive power to the advanced reactive power, thereby accurately adjusting the receiving voltage to the set reference voltage regardless of the load type. can be controlled.

[Brief explanation of drawings]

FIG. 1 is a detailed explanatory diagram of the first invention, FIG. 2 is a diagram showing the relationship between reactive power and rotor position according to the same embodiment, and FIG. 3 is an illustration of an embodiment of the first invention. FIG. 4 is an explanatory diagram of an embodiment of the second invention, and FIG. 5 is an explanatory diagram of adjusting the receiving end voltage. 1... Rotor, 2... Stator, 3... Rotor shaft,
4... Worm gear, 5... Worm, 6... Delayed reactive power adjustment device, M... Phase shifter, T... Transformer, L, L+ ~ ln... Reactor, Co, C+ -Qn ++Capacitor, force diagram 2

Claims (2)

[Claims] (1) A plurality of reactors are each connected to a power source in parallel through a first switch, and have a phase shifter and a transformer consisting of a rotor and a stator, and the rotor and fixed A winding is wound around each child, and the terminal of the winding wound around the rotor is connected to the secondary terminal of the transformer, and one of the rotor and the stator is connected to the other. The primary side terminal of the transformer, the terminal of the winding wound around the stator, and the capacitor of the reactive power regulator, which has a rotating means for rotating and positioning, are connected in parallel to the terminals of each of the reactors. Connect it through switch 2, compare the power supply voltage and the set reference voltage,
A voltage control method that controls the first and second switches and the rotating means according to the difference to adjust reactive power and perform voltage control. (2) A plurality of reactors and a plurality of capacitors are each connected to a power source via a first switch, and the rotor of the phase shifter has a phase shifter and a transformer consisting of a rotor and a stator. A winding is wound around each of the stator and the rotor, and the terminal of the winding wound around the rotor and the secondary terminal of the transformer are connected, and one of the rotor and the stator is connected to the other. The primary side terminal of the transformer and the terminal of the winding wound around the stator are connected in parallel to the terminals of the reactors and the terminals of each capacitor of the reactive power adjusting device, which has a rotating means for rotating and positioning the transformer. Connect to the terminals through each second switch, compare the power supply voltage and the set reference voltage, and adjust the voltage between the first and second switches according to the difference.
A voltage control method that controls the switch and the rotating means to adjust reactive power and control voltage.