JP2001268795A - Voltage control method of distribution line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control voltage regulation of a load center point to an allowable value. SOLUTION: An SVR(step voltage control unit) and an SVC (series type voltage control unit) are installed in a distribution line. The SVC makes the voltage regulation ε of a voltage VL of a load center point (a) viewed from a primary voltage V1 the starting condition. In order to avoid the start of the SVC due to gentle voltage change and surely compensate sharp voltage change only, ε is obtained by setting the magnitude of the load center point voltage before ΔT seconds (changing value reference time) obtained by moving average processing of the voltage VL as a reference voltage VLref. Concerning a voltage V2' of the point (a) viewed from a secondary voltage V2, a voltage regulation ε' to VLref is obtained. A generating voltage VC of the SVC is so controlled that ε' becomes the allowable value α. When a load L changes quickly and ε is larger than α, the SVC starts and controls to obtain a relation of ε'=α. After that, the SVR starts late, and steps up or down one tap. In the case of ε<α, the SVC stops.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a series voltage controller and a voltage control method for a distribution line by combining the voltage controller with a step voltage controller.

[0002]

2. Description of the Related Art The applicant of the present invention has previously proposed a voltage control method for a power system in which a step voltage control device (SVR device) and a series voltage control device (series SVC device) are combined. (Japanese Patent Application No. 10-168051).

The above voltage control method will be described with reference to FIG. It should be noted that vector symbols of voltage and current are omitted in the text. SV on distribution line from grid power supply (distribution substation) PS
The R device 1 is connected, and the serial type SVC device 2 is installed close to the downstream side. Since the SVR device 1 can perform only slow voltage fluctuation compensation, the series-type SVC device 2 performs rapid voltage fluctuation compensation.

As shown in FIG. 13, the SVR device 1 comprises a tap switching transformer 1a and a 90 relay 1b, and the 90 relay 1b is a voltage _{VL at} a load center point a as viewed from a secondary voltage V2 of the SVR device 1. = {V ₂ − (R + jX) I}, the difference from the reference voltage Vref is taken, and the difference is integrated by the integration circuit 11. When the size exceeds the operation time set value, the tap is raised (or A lowering) command is output to the tap switching transformer 1a to control the voltage on the load side. However, integration is not performed unless the magnitude of this difference exceeds the dead zone.

FIG. 15 shows a change in the load center point voltage when the SVR device 1 controls the load center point voltage. In principle, the SVR device takes several minutes to output the tap-up (lower) command, and if there is a difference (more than the dead zone) between the load center point voltage and the reference voltage even after tap control, the tap-up (lower) command is further output. It takes several minutes.

[0006] As shown in FIG. 14, a serial type SVC device 2 includes a parallel transformer Ta and a series transformer T connected to a distribution line.
b and a self-excited converter 2a and a self-excited inverter 2b connected between the transformers Ta and Tb.

The serial type SVC device 2 has a primary side voltage V _1.
And the current I on the secondary side is input to the control circuit of the self-excited inverter to perform voltage control. That is, the reference voltage Vre the voltages V ₁
f to increase the voltage, the voltage V _{C in} phase with the voltage V ₁
Is generated, and when the voltage is reduced, a voltage V _C having an opposite phase to the voltage V ₁ is generated. The magnitude of the voltage V _C to be generated is controlled to be in-line SVC device 2 of the voltage V _L of the load center point a obtained from the secondary voltage V ₂ magnitude reference voltage Vref (= V ₁₎ .

[0008]

(Equation 1)

The voltages V ₁ and V ₂ have the same phase, and the SVR device 1
The position a of the load center point of the series SVC device 2 and the reference voltage Vref have the same value as the size of the dead zone.

[0010]

The voltage control method described above is
The SVR device and the series type SVC device are used together, and a slow voltage change is compensated only by the SVR device, and a sudden voltage change is compensated for by the SVR device.
Complement with a VC device. This serial type SVC device controls the primary side voltage as a reference voltage. SV for that
The condition is that a series-type SVC device is installed close to the load side (downstream side) of the R device.

By the way, when compensating the voltage of the distribution line,
Both the SVR device and the serial type SVC device will be mounted on the distribution pole. For this reason, it is considered that the conditions for disposing them in close proximity are limited and may be difficult in practice.

According to the present invention, when the series-type SVC device can control the fluctuation of the load center point voltage constant without using the primary side voltage as a reference, and when the SVR device and the series-type SVC device perform cooperative control, It is an object of the present invention to provide a voltage control method for a distribution line that can perform voltage compensation of a distribution line between an SVR device and a series-type SVC device without imposing any conditions.

[0013]

SUMMARY OF THE INVENTION A voltage control method for a distribution line according to the present invention comprises a series transformer connected in series to the distribution line and receiving power from the line to output reactive power or active power to the series transformer. And a power converter for controlling the output power of the series transformer, and a series-type voltage control device is installed. The voltage at the load center point is calculated from the current, and the voltage fluctuation at the load center point is controlled to a constant value.

In the calculation of the voltage fluctuation at the load center point, it is preferable that a moving average value of the load center point voltage for a predetermined time is obtained, and this moving average value a predetermined time before is always calculated as a voltage reference value.

Further, it is preferable that the series-type voltage control device is started under the condition that the magnitude of the load center point voltage fluctuation is equal to or larger than a set value.

In the above-mentioned series voltage control device, the phase of the generated voltage may be controlled to be in phase with the primary voltage of the device in the voltage increasing direction and opposite to the voltage in the voltage decreasing direction.

Further, the variation of the load center point voltage is obtained by always calculating a moving average value of the primary side voltage of the series type voltage controller before the load center point voltage for a fixed time, and a primary side voltage of the device. , And the impedance up to the load center point and the line current may be controlled to a set value.

Alternatively, a tap transformer for adjusting the voltage of the distribution line, and a voltage for outputting a tap switching command of the tap transformer so that the load center point voltage viewed from the secondary voltage of the tap transformer becomes a reference voltage. In addition to installing a step voltage control device consisting of an adjustment relay, the series voltage control device controls and compensates for the voltage fluctuation at the load center point to a constant value, so that taps are not restricted by the installation location of the device. It performs cooperative control with a step voltage control device including a transformer and a voltage adjustment relay that outputs a tap switching command.

The voltage fluctuation is calculated by always using a value before a moving average value of the load center point voltage for a fixed time (a fluctuation value reference time) as a reference voltage, and a period during which the step voltage control device cannot respond is a series type voltage. To ensure that the control device compensates and performs cooperative control, it is preferable to predict the tap control time from the set value of the step voltage control device and set the fluctuation value reference time longer than this time.

In addition, the above step voltage control device controls the primary-side voltage, line current, line impedance to the load center point, and load of the series type voltage control device on the primary and secondary sides of the voltage which is too short or too short to maintain the load center point at the reference voltage. The generated voltage may be calculated and compensated from the set value of the voltage fluctuation at the center point.

Further, the above-mentioned step voltage control device applies an excess or deficiency voltage to maintain the load center point voltage at the reference voltage with respect to the load center point voltage of the primary side voltage of the device from the series type voltage control device. The generated voltage may be calculated and compensated from the moving average value a predetermined time before the start instant, the primary voltage thereof, the impedance to the load center point, and the line current.

When there is a distributed power source in the distribution line, forward / reverse transmission is determined based on the relationship between the phase relationship of the current corresponding to the line current change and the positive / negative sign of voltage increase / decrease using the voltage as a reference vector. The series voltage controller may be operated.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment As shown in FIG. 1, an SVR device 1 is provided on a distribution line, and a series-type SVC device 2 is provided downstream thereof, and a load center point (target point) a for which voltage is to be compensated. Is determined. The SVR device 1 and the serial type SVC device 2 have the configurations shown in FIGS. 13 and 14 described in the related art.

First, the load center by the series type SVC device 2
A method of controlling the point voltage will be described. Load center point a
When the pressure fluctuation rate exceeds the allowable value α, the series type SVC device 2
Start and maintain the voltage fluctuation rate at the load center point a at α
Thus, the generated voltage of the serial type SVC device 2 is controlled. That
Therefore, the primary side voltage V of the serial type SVC device 2 is as follows. ₁
Voltage V at the load center point_LStartup of voltage fluctuation rate
Conditions.

[0025]

(Equation 2)

Also, a series type SVC due to a slow voltage fluctuation
In order to avoid the start-up of the device 2 and reliably compensate only for abrupt voltage fluctuations, a fluctuation value reference time obtained by performing a moving average process on the load center point voltage △ the magnitude of the load center point voltage before T time As the voltage V _L ref, the current load center point voltage V _L
The voltage fluctuation rate ε (%) having the magnitude of is calculated.

[0027]

(Equation 3)

This voltage fluctuation rate ε is compared with an allowable value α, and ε
If> α, activate the series SVC device. The load center point voltage V _L ′ viewed from the secondary side of this device is

[0029]

(Equation 4)

A voltage variation rate ε ′ of the load center point voltage V _L ′ with respect to the reference voltage V _L ref is determined.

[0031]

(Equation 5)

The voltage fluctuation rate ε 'is set to the allowable value α.
And the generated voltage V of the series SVC device _CControl the size of
You.

FIG. 2 shows the current voltage and the reference voltage for the load center point voltage V _L. The current voltage _VL is the average value of the magnitude of the load center point voltage for several cycles from now,
The reference voltage V _L ref is an average value of the magnitude of the load center point voltage at time T ₀ (reference voltage average time) before ΔT time (variation value reference time) before the present time.

The generated voltage V _C of the serial type SVC device 2 is obtained as follows. FIG. 3 shows a vector diagram. Series type SV
A component in-phase with the primary voltage V ₁ of the C device 2 is expressed as a q-axis component, and a component advanced by 90 ° from this is expressed as a d-axis component.

[0035] The voltage V _L 'of the tandem SVC 2-side voltage V ₂ viewed from the load center point of the device 2, is represented by d · q-axis component,

[0036]

[6] _{V L 'q + V L'} d = (V 1q + jV 1d) + (V Cq + jV Cd)
- (r + jx) (I q + jI d) V C is V ₁ and phase or opposite phase, V ₁ is so q-axis component, a _{V 1 d = 0, V Cd} = 0.

[0037]

(Equation 7)

[0038]

(Equation 8)

The reference voltage V _L ref at the load center point when the voltage drops due to a sudden change in the load, the voltage deviation ΔV between the current voltage and the reference voltage, and the primary and secondary voltages of the series SVC device 2 FIG. 4 shows the voltage fluctuation rates ε and ε ′.

Referring to FIG. 4, a sudden load change occurs, and the load center point voltage _VL decreases. Since the reference voltage V _L ref is the average value of the magnitude of the load center point voltage before ΔT time from the present time, the load center point voltage V is reduced linearly after T ₀ seconds without changing for ΔT time. It becomes equal to _L. Also, voltage deviation △ V
= V _L -V _L ref also does not change for ΔT time and then decreases linearly and becomes ΔV = 0 after T ₀ seconds.

Therefore, the voltage fluctuation rate ε '(%)
It increases simultaneously with sudden changes. In the case of FIG. 4, the voltage at the time of sudden load change
Since the fluctuation rate ε exceeds the allowable value α,
The serial type SVC device 2 is activated in the
Allow voltage fluctuation rate ε '(%) at the load center point as viewed from the secondary side
In order to maintain the capacitance α, the series SVC device 2 _C
Occurs.

The reference voltage V _L ref which exceeds ΔT time (variation value reference time) from the above voltage change starts to take the value after the voltage change for the calculation of the average value, and the value gradually approaches zero. It becomes zero after T ₀ time (reference voltage average time).

During this time, the voltage fluctuation rate ε becomes smaller than the allowable value α, and the serial type SVC device 2 stops. Series type SVC
When the device 2 stops, the voltage fluctuation rates ε and ε ′ eventually become zero. The distribution line voltage continues to decrease with the stop of the series-type SVC device 2, but cooperates with the SVR device 1 as described later. Since the T time is set to be longer than the time during which the SVR device 1 can operate, the voltage fluctuation rate ε Can be maintained below the allowable value α.

FIG. 5 shows the relationship between the installation position of the series type SVC device 2 and the voltage fluctuation rates ε and ε ′ at each point of the distribution line.
In the series type SVC device 2, the device load side is compensated to make the voltage fluctuation rate from the distribution substation (system power supply) to the load center point equal to or less than an allowable value. The series-type SVC device 2 can maintain the voltage fluctuation at the load center point at the allowable value α by the above-described voltage calculation method regardless of the installation position.

Next, operation coordination between the SVR device 1 and the serial type SVC device 2 will be described. FIG. 6 shows a time transition of the voltage fluctuation rate of the distribution line in which the series SVC device 2 is arranged on the load side of the SVR device 1. In both cases, the load center point is at the end.

Referring to FIG. 6, immediately after the occurrence of the voltage fluctuation, S
Since the VR device 1 can not respond, tandem SVC device 2 maintains the voltage regulation of the voltage V _C output to the load center point a epsilon in tolerance alpha.

Thereafter, the SVR device 1 raises the tap because the integration time according to the deviation between the load center point voltage and the reference voltage (set value) as viewed from the load side voltage reaches the set value. Since the power source side voltage of the series type SVC apparatus 2 by the operation of the SVR device 1 voltage by one tap of SVR device 1 is compensated, the compensation voltage V _C of the series type SVC device 2 decreases.

Thereafter, as the tap operation of the SVR device 1 proceeds, the compensation voltage V _C of the serial type SVC device 2 decreases.
When the voltage variation rate of the load center point becomes equal to or less than the allowable value as shown in, compensation voltage V _C of the series type SVC device 2 becomes zero.

As described above, since the tap operation of the SVR device 1 and the compensation operation of the series SVC device 2 are independent,
Immediately after the voltage fluctuation, the series-type SVC device 2 can perform operation coordination in which the SVR device compensates for the voltage fluctuation stepwise thereafter.

The above is a case where the serial type SVC device 2 is installed on the load side of the SVR device.
Are different from those described above in the case where is installed on the power supply side with respect to the SVR device 1. In this case, cooperative control can be performed by appropriately setting the reference time ΔT of the moving average value, that is, the fluctuation value reference time ΔT in FIG.

The above method can be applied to a case where a plurality of SVR devices are installed on the same track.

A digital simulation result on operation coordination performance when the series type SVC device 2 is installed on the load side of the SVR device 1 will be described. As shown in FIG. 7, the circuit to be analyzed is 10 k
A synchronous generator G was selected at the end of the m distribution line (# 7) to simulate the generator falling off during operation at an output of 1 [MW] (power factor of 1).
The load center point of the SVR device (SVR) and the series type SVC device (SVC) was at the end of the distribution line, and the allowable value of voltage fluctuation rate (set value) was 5%. The installation points of SVR and SVC were 4 km and 6 km from the substation, respectively.

FIG. 8 shows the simulation results. Immediately after the synchronous generator, which is a sudden change in load, falls short of the SVR device.
The voltage fluctuation rate ε at the load center point (# 7) as viewed from the secondary (# 4) voltage is 7.7%. The allowable value of the voltage fluctuation rate ε is 5
%, The series-type SVC device starts up, and the series-type SVC device generates a voltage such that the voltage fluctuation rate ε ′ at the load center point as viewed from the secondary (# 5) voltage of the device becomes 5% of the allowable value. Control. As a result, the voltage fluctuation rate ε ′ at the load center point is 4.9%, and the voltage fluctuation rate of the entire distribution line is 5% of the allowable value.
% Or less.

After about 8 seconds have passed since the synchronous generator was dropped, the SVR device is operated to perform tap control (corresponding to 1.5% in voltage fluctuation rate). Since the voltage fluctuation rate at the load center point as viewed from the primary voltage of the series type SVC device is 6.1%, the series SVC device continues to be activated, and the voltage fluctuation at the load center point as viewed from the secondary voltage of this device. The generated voltage is controlled so that the rate ε 'is maintained at 5%, but the generated voltage, which is voltage-controlled by the SVR device (corresponding to a voltage fluctuation rate of 1.5%), becomes small.

Since another 10 seconds have passed since the SVR device performed one tap control (18 seconds after the synchronous generator was dropped), S
When the VR device operates and is controlled by two taps, the serial type SV
Since the voltage fluctuation rate at the load center point as viewed from the primary voltage of the C device becomes 4.2%, the SVR device stops. However, S
Since the voltage fluctuation rate of the entire distribution line is 5% or less of the allowable value due to the operation of the VR device, the target voltage control is achieved, and the operation coordination between the SVR device and the series SVR device is favorably performed.

This operation coordination predicts the tap control time for the voltage fluctuation from the set value of the SVR device, etc., and takes into account this, the ΔT time (variation value reference time) of the serial type SVC device.
Is made well by deciding.

Embodiment 2 The normal load current of the series-type SVC device flows from the power supply end (distribution substation) toward the load. However, recently, a distributed power supply has been introduced into a distribution system, and this power supply may cause a current direction to a power supply end when viewed from a series-type SVC device. This is called reverse flow.

FIGS. 9A and 9B show a state in which there is no backflow in the forward feeding state and there is a backflow. The progressive transfer refers to a state where power is constantly supplied from the distribution substation PS1. On the other hand, when power cannot be supplied from the distribution substation PS1 due to an accident or the like, power may be supplied from another distribution substation (distributed power supply) PS2. A state in which the flow is opposite to that in the forward transmission is called reverse transmission. FIGS. 10A and 10B show a state in which there is no reverse power flow and a state in which there is a reverse power flow in the reverse transmission state.

In the second embodiment, regardless of the presence or absence of a reverse power flow, the forward and reverse conditions are automatically determined, and the serial SVC device is operated only during the forward transport. The reason why the series-type SVC device is not operated at the time of reverse transmission is that the load terminal is in the opposite direction as viewed from the power supply terminal PS1. If there is no reverse power flow, it is possible to determine forward or reverse in the normal current direction. However, in consideration of the reverse power flow, it is impossible to determine by the forward / reverse transmission discrimination method.

Referring to FIG. 11, a distributed power source PS for distribution lines
A series-type SVC device 2 is provided upstream (distribution substation PS1 side) of 2 to compensate for transient voltage fluctuation such as when the load L2 is turned on. The current when the load L2 is applied is the distribution substation PS
1 and distributed power supply PS2. Therefore, as shown in FIG. 11, the current change ΔI due to the load application on the load L2 side from the series type SVC device 2 in the direction of the input load from the distribution substation PS1 is the same as in the case where there is a reverse power flow and no reverse power flow. Become. In load shedding, the direction of current change is reversed.

[0061] determining the sign of the in-line SVC change in the supply-side voltage V ₁ of the device 2 min △ V ₁ of the this case. Assuming that the effective portion of the current change due to the sudden load input is △ Ip and the ineffective portion is △ Iq, △ V ₁ is [Equation 9].

[0062]

△ V ₁ = −√3 (Re △ Ip + Xe △ Iq)
However, Re, Xe: distribution line resistance from the distribution substation to the SVC installation point, reactance ΔIp, ΔIq: valid, reactive current change (increase direction is positive). Reactive current has a positive delay) Aluminum wire 120mm ² has Re = 0.25Ω per unit length
/ Km and Xe = 0.35Ω / km. Therefore, when a load with a load power factor advance of 0.80 (phase angle 40 °) is applied, the voltage drop due to the active current and the voltage rise due to the advance reactive current cancel each other out, and the voltage change becomes zero. When the power factor (lead) decreases from this, the sign of the voltage change becomes positive because the voltage rise due to the advance reactive current exceeds the voltage drop due to the effective component (voltage increase).

On the other hand, when the power factor is larger than 0.80, or when the load is delayed, the voltage rise due to the leading reactive current is small or the voltage drop due to the delayed reactive current is large. The sign of the minute becomes negative (voltage drop).

This property is established by the distributed voltage irrespective of the power flow state (with or without reverse power flow) at the location of the SVC device. (Right half of FIG. 12 (a)). At the time of load shedding, the relationship is the opposite of that at the time of application (the left half of FIG. 12A).

FIG. 12 (b) shows the relationship under the reverse transmission condition.
As shown in FIG.

[0066]

[Table 1]

Therefore, as shown in Table 1, the phase relationship between the primary voltage V ₁ of the serial type SVC and the current change ΔI and the sign of the change in the magnitude of the voltage (positive when the voltage increases and negative when the voltage decreases) ) Can determine forward / reverse transmission. The serial type SVC device is enabled only when the result of the forward / reverse determination is forward, and the voltage fluctuation at the load point at the time of forward feed is controlled in the same manner as in the first embodiment.

[0068]

Since the present invention is configured as described above, the following effects can be obtained.

(1) The load center point voltage fluctuation rate can be made equal to or less than an allowable value without restricting the installation location.

(2) The serial type SVC device is started under the condition that the magnitude of the voltage fluctuation at the load center point is equal to or larger than the set value.

(3) When the variation of the voltage at the load center point of the series-type SVC device is calculated from the reference voltage obtained from a constant time (variation value reference time) of the moving average value of the load center point voltage, the variation value When the reference time is exceeded, the voltage fluctuation rate becomes smaller than the allowable value, and the serial type SVC device stops.

(4) Cooperative control between the SVR device and the serial type SVC device is facilitated.

(5) A reliable start-up is performed in response to a voltage fluctuation during forward feeding, and a compensation voltage is generated.

(6) Since only the voltage fluctuation is compensated, a reduction in the device capacity can be expected.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of cooperative control of an SVR device and a serial type SVC device.

FIG. 2 is an explanatory diagram of voltages used for calculation.

FIG. 3 is a vector diagram illustrating a generated voltage of the serial type SVC device.

FIG. 4 is a graph showing a voltage fluctuation rate as viewed from a primary side voltage and a secondary side voltage of a serial type SVC device.

FIG. 5 is a graph showing an installation position of a series type SVC device and a voltage fluctuation rate at each point of a distribution line.

FIG. 6 is a conceptual diagram showing a time change of a voltage fluctuation rate of a distribution line in cooperative control of an SVR device and a serial type SVC device.

FIG. 7 is an analysis target circuit diagram.

FIG. 8 is a graph showing simulation results.

FIG. 9 is a distribution line diagram of a serial type SVC device installed showing a progressive state.

FIG. 10 is a distribution line diagram of a series type SVC device installation showing a reverse feed state.

FIG. 11 is an explanatory diagram of a current change direction due to loading of a load in the presence of reverse power flow in a forward condition.

FIG. 12 is a graph showing a phase relationship between voltage and current.

FIG. 13 is a block diagram showing a configuration of the SVR device.

FIG. 14 is a block diagram showing a configuration of a serial type SVC device.

FIG. 15 is an explanatory diagram of a voltage drop due to a load input to a conventional SVR device distribution line.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... SVR apparatus (step voltage control apparatus) 2 ... Series type SVC apparatus (series type voltage control apparatus) ε ... Voltage fluctuation rate of load center point viewed from primary side voltage of series type SVC apparatus ε '... series type SVC apparatus Of voltage change at the load center point as seen from the secondary side voltage

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nobuyuki Fujiwara 4-1 Egasakicho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Within the Electric Power Research Laboratory, Tokyo Electric Power Company (72) Inventor Ichiro Sumiya E, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture 4-1, Kasaki-cho, Tokyo Electric Power Company, Electric Power Research Institute (72) Inventor Takaaki Kai 2-1-1-17, Osaki, Shinagawa-ku, Tokyo Inside Meidensha Co., Ltd. (72) Inventor Tatsunori Sato, Osaki, Shinagawa-ku, Tokyo 2-1-1-17 F-term in Meidensha Co., Ltd. (reference) 5G066 DA01 DA04 DA07 5H420 BB03 CC04 DD03 EA29 EA30 EA49 EB38

Claims (9)

[Claims] 1. A series transformer connected in series to a distribution line, a power converter receiving power from the line, outputting reactive power or active power to the series transformer, and controlling output power of the series transformer. The voltage at the center of the load is calculated from the voltage on the primary side of the device and the line impedance and the line current to the load center, which is the target point to be compensated. A voltage control method for a distribution line, wherein the voltage is controlled to a constant value. 2. The method according to claim 1, wherein a moving average value of the load center point voltage for a predetermined time is obtained as a voltage fluctuation at the load center point, and a moving average value before a fluctuation value reference time, which is always a fixed time, is calculated as a voltage reference. A voltage control method for a distribution line, which is calculated as a value. 3. The voltage control method for a distribution line according to claim 1, wherein the series voltage control device is started under a condition that a magnitude of a voltage fluctuation at a load center point is equal to or larger than a set value. 4. The method according to claim 1, wherein the phase of the voltage generated by the series-type voltage control device is controlled to be in phase with the primary voltage of the device in the voltage increasing direction and opposite to the voltage in the voltage decreasing direction. A voltage control method for a distribution line, comprising: 5. The method according to claim 1, wherein the set value and the voltage reference value are set so as to make the voltage fluctuation at the load center point a constant value.
A voltage control method for a distribution line, comprising calculating a control voltage from a primary-side voltage, a line current, and an impedance to a load center point of a series voltage controller. 6. A step voltage controller and a series voltage controller comprising a tap transformer and a voltage adjusting relay for outputting a tap switching command are installed on a distribution line, and the series voltage controller is configured to control a load center point voltage fluctuation. A voltage control method for a distribution line, comprising: performing a coordinated control with a step voltage control device by controlling the number of minutes to be constant, without being restricted by an installation location of the series-type voltage control device. 7. The method according to claim 6, wherein a tap control time is predicted from a set value of the step voltage control device, and a reference value is calculated by determining a fluctuation value reference time of the series voltage control device in consideration of the tap control time. A voltage control method for a distribution line, wherein cooperative control can be performed by generating and compensating for the voltage. 8. The voltage controller according to claim 6, wherein the voltage that is excessive or insufficient to maintain the load center point voltage of the step voltage controller at the reference voltage is determined by the series type voltage controller as the set value of the voltage fluctuation at the load center point. A voltage control method for a distribution line, comprising calculating and compensating a generated voltage from a voltage on a primary side of a device, a line current, and an impedance to a load center point. 9. The method according to claim 1, wherein forward or backward transmission is determined by using a voltage as a reference vector in accordance with a phase relationship of a change in line current and a relationship between directions of voltage increase and decrease.
A voltage control method for a distribution line, wherein a series-type voltage control device is operated only during forward feeding.