JPH0785624B2 - Voltage / reactive power control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is provided with a monitoring control device at a main point that interconnects a power supply side and a load side of a power system, and monitors the power supply status and load of the high voltage side and the low voltage side. The present invention relates to a voltage / reactive power control device that detects a voltage stable state and performs arithmetic processing to appropriately adjust and maintain a voltage of a system and an inflow / outflow reactive power flow.

[Conventional technology]

In recent power systems, due to the increase in power demand and difficulty in location of power facilities due to environmental problems, etc., on the generation side, remote distribution of facility locations and large-scale power supply bases with large-capacity units have emerged. In terms of power transmission equipment, it has come to become long-distance, high-voltage, and large-capacity, and has come to take on the aspect of heavy flow of operation.

Although there are some problems to safely and economically operate the high-density and large-capacity power system that continues to expand and complex year by year, it is difficult to directly evaluate the effect of the voltage problem. However, there are many problems to be solved as power quality problems. For example, (a) voltage drop during heavy load (b) abnormal voltage rise during light load (c) voltage drop during system failure (d) improved voltage / reactive power control function during normal system operation, etc.

Is.

The above (1) and (2) are summarized as follows, as described in Technical Report of the Institute of Electrical Engineers of Japan (Part II), No. 233, page 60. That is, generally, the voltage of the power system is maintained and adjusted to a preset reference value by the voltage of the generator, the transformer, the phase adjusting equipment, and the reactive power control.

However, due to the enormous size of the grid as described above, when the large power supply is dropped or the load is rapidly increasing, and when the supply and demand for reactive power is unbalanced, the voltage of the main grid abnormally drops or rises, causing abnormal voltage. The phenomenon occurs although it is rare.

[Problems to be solved by the invention]

Since the conventional voltage / reactive power control device is operated as described above, if a voltage abnormality or an unstable phenomenon occurs, an imbalance between the power supply and the load occurs and if the conditions are met, the phenomenon that occurs locally cannot be suppressed. However, there is a problem in that it may spread to the entire system and cause an electric power abnormality, and that it requires prompt prediction and stabilization measures for the entire system.

The present invention has been made to solve the above problems, and while the prediction and countermeasures for this kind of abnormality were mainly entrusted to the side of the power supply station that controls the operation of the entire system, the present invention The occurrence of
It is an object of the present invention to obtain a voltage / reactive power control device that appropriately maintains the stability of voltage and appropriately controls voltage / reactive power by taking measures against the above-mentioned abnormality in coordination with the overall adjustment control.

[Means for Solving Problems] A voltage / reactive power control device according to the present invention is installed at an electric station at a main point that interconnects a power supply side of a power system and a load side line, and a high voltage system side busbar and a low voltage system. A transformer bank is connected to the system side bus to detect the voltage and power flow of the high voltage system side bus, the voltage and power flow of the low voltage system side bus, and the voltage and power flow of the tertiary side of the transformer bank, respectively. Input to the supervisory control device, and the output signal processed by the supervisory control device is fetched into the first and second switchboards and the information transmission device to control the phase adjusting equipment coupled to the transformer bank. It is a thing.

[Action]

The supervisory control device according to the present invention has a microcontroller, and detects and takes in the voltage and power flow of the high-voltage system side bus, the low-voltage system side bus, and the tertiary side of the transformer bank, respectively, and performs the multiplexer and A / D conversion. It is input to the above-mentioned microcontroller via the above to execute the operation for stabilizing and adjusting the system voltage and output the control command to the phase adjusting equipment.

Example of Invention

Hereinafter, the operation principle of one embodiment of the present invention will be described. First, in FIG. 1, 1 is a high-voltage power supply system, 2 is a low-voltage power supply system, 3 is a transformer bank that connects both high and low-voltage systems, and 4 is a phase-modulating facility on the tertiary side of the transformer bank 3. 5,
Is the load feeder.

In addition, although a system having two power supplies is considered in practice, both are contracted here as one power system for simplicity.

Then, the voltage of the upper (high voltage) side bus bar is V _t1 , the reactance of the system behind the upper side bus bar is x _g1 , and the lower side (low voltage)
Let V _{t2 be} the voltage of the side bus and x _g2 be the reactance of the lower back system. Let the leakage reactance of the primary side of the transformer bank 3 be x _t1 , and let the leakage reactance of the secondary side be x _t2 ,
Let V be the induced voltage of an ideal (virtual) transformer inside the transformer bank 3.

In addition, the number of turns of the load tap changer (tap changer) on the primary side of the transformer is set to n: 1, and the number of turns can be changed by Δn.

Let Q be the reactive power flow that flows from the primary system to the secondary system.

Next, the operation will be described. First, there are equations (1.1) and (1.2) as well-known relational expressions of the voltage change ΔV of the ideal transformer and the change ΔQ of the reactive power flow.

However, x _o = x _g1 + x _t1 + x _g2 + x _t2 (1.3) Further, the voltages ΔV _t1 and ΔV _t2 of the primary system bus and the secondary system bus are given by (1.4) and (1.5).

As described above, the transformer primary side reactive power flow change ΔQ and the primary and secondary system bus voltage changes ΔV _t1 and ΔV _t2 are the voltage of the system back voltage and the voltage changes ΔV _g1 and ΔV _{g2 at} low voltage and the transformer. Change Δn in winding ratio: Determined by change Δq in reactive power supply.

Next, consider the load system in the low-voltage (lower) system side bus 20.

First, the low-voltage system side bus 20 has a voltage V _t2 (≡
V _L ) is being output, and the total W of all feeder loads from the feeder 51 to the feeder 5n is being supplied. When looking at the power supply side from the low voltage system side bus 20, its impedance Z is expressed by equation (1.6).

If all the feeder loads W mentioned above are connected to this system, the reference voltage of the system is V _S , the short-circuit capacity is S, and Using the values standardized by v _L ² = v _L ⁴ + 2w cos (−θ) · v _L ² + w as shown in Technical Report of the Institute of Electrical Engineers of Japan (Part II), No. 73, page 52. ² …… (1.8) There is a relationship.

Here, the power factor angle of impedance Z and θ are the power factor angles of all feeder loads W.

Also, by using this value, the power flow of each feeder in the low voltage system side bus 20 and the maximum value of the voltage W _L , V _L are Becomes (Literature, Technical Report of The Institute of Electrical Engineers of Japan (Part II), No. 73,
(Refer to page 52) Furthermore, in the load substation busbars 61 ... 6n at the other end, the impedance Z _S1 ... Z _Sn and its power factor of ₁ ... _n when looking at the power source side from the busbars ... 61… 6n When the load power factor when viewed from the load side is θ ₁ … θ _n and other quantities, v _Li ² = v _Li ⁴ + 2w _Li cos ( _i −θ _i ) + w _Li ² …… (1.1
1) (i = 1 ... n) There is a relationship.

Next, a system to which the present invention is applied will be described.

In the figure, the same parts in FIG. 1 are shown with the same reference numerals, and in FIG. 2, it is assumed that the tidal current flows from the high-voltage power supply system 1 toward the low-voltage power supply system 2. Further, it is assumed that the reactive power flow 9 is supplied from the phase adjusting equipment 4, and the contribution is flowing to the low-voltage power supply system 2 side.

Also, from the low voltage system side bus bar 20 on the low voltage power supply system 2 side,
Feeder 51… 5n is pulled out and the current of the feeder is w ₁ … w _n
It is assumed that the other end load substation 61 ... 6n is flowing toward.

The system that supplies power to the feeders 51 ... 5n is the upper level (high voltage)
There is 11… 1t from the side and 21… 2m from the lower side (low voltage) side, and the effective component is the load substation busbars 61… 6n from the other side to the feeder 51… 5n.
Shall not flow in the direction of.

As shown in FIG. 2, the voltage / current of such a system is introduced into the monitoring control device 7 through the transformers 101, 201 and the current transformers CT32, 511 ... 5n1 and subjected to the calculation determination processing described later. The load tap changer 30, the static capacitor 42, and the shunt reactor 41 are controlled via the switchboards 81 and 82.

As described above, in the power system with two power supply systems, one group of loads, and one transformer bank as a unit, the power flow passing through the primary and secondary of the transformer bank 3 and the voltage of the primary and secondary are measured. The primary side tap and the tertiary side phase adjusting equipment are operated to stabilize and adjust the system voltage.

Next, specific examples of the present invention will be described.

FIG. 3 is a detailed block diagram of the present invention.

11 ... 1m, 1n ... 1 as a power transmission line that constitutes the high-voltage power supply system 1
It is assumed that there is z and the transmission lines 11 ... 1m are the inflow side of the tidal current and the transmission lines 1n ... 1z are the outflow side of the tidal current.

10 is a high-voltage system side busbar that interconnects this transmission line group, and the busbar voltage is measured by the transformer PT101.

There are 21 ... 2m as a power transmission line that constitutes the low voltage power supply system 2, and a feeder is provided as a load system via the low voltage system side bus 20.
51 ... 5n are connected. The voltage of the load system is (load side)
By the transformer PT201, the current of each feeder 51 ... 5n is measured by arranging each CT of the (load side) current transformers 511,521, ... 5n1.

There is a transformer bank 3 that connects a high-voltage power supply system 1 and a low-voltage power supply system 2, and a load tap changer 30 is attached to adjust the voltage.

The primary power flow is measured by the current transformer CT31, and the secondary power flow is measured by the current transformer CT32.

On the tertiary side of the transformer bank 3, there is a phase adjusting equipment group 40 ... 44,
A shunt reactor 41 and a static capacitor 42 are connected to the phase adjusting facility bus 40 via breakers 43 and 44.

The voltage and current on the tertiary side of this transformer bank 3 are transformer PT4
5, can be measured by current transformer CT46.

The voltage and current measured through each measuring transformer PT and the current transformer CT in the arrangement of the main circuit device measuring instrument as described above are introduced into the monitoring control device 7.

That is, the voltage of the high voltage side system bus 10 is the transformer PT101, the primary current of the transformer bank 3 is the current transformer CT31, the low voltage system side bus 20.
Is the transformer PT201 transformer bank 3 secondary current is transformer CT32, transformer bank 3 tertiary voltage is transformer PT45,
Similarly, the current is measured by the current transformer CT46, and the current of the feeders 51 ... 5n connected to the low voltage system side bus 20 is measured by the current transformer CT511 ... 5n1.

The transmission lines 21 ... 2m are lines that can be both a power source and a load and can be assumed to be a power source behind. The power flow in that part is temporarily removed from the measurement, but voltage control is possible at other electric stations. And

Numeral 7 receives as input data of the states of each part of the system as described above and has a supervisory control circuit device mainly composed of a micro-controller inside, and executes the following functions to output the output to the distribution boards 81, 82 and information. Outputs to the transmission device 9.

The first switchboard 81 is a transformer voltage regulator board, which issues a command to raise / lower the load tap changer 30. The second switchboard 82 is a third-order phase control device control panel of the transformer bank 3 and issues an operation signal to the breakers 43 and 44 for turning on and off the branch reactor 41 and the static capacitor 42.

Reference numeral 9 denotes an information transmission device, which is the state of the monitoring control device 7,
It is a device for transmitting the output of commands and the like to other electric stations, and is usually known as a telemeter or a transmission device.

The monitoring and control device 7 configured as described above uses the voltage and current of each part of the system as measurement input signals, converts them into digital signals internally, performs digital calculation and determination processing by the microcontroller, and outputs the results as operation commands, or The information is output to other electric stations. Details of the monitoring control device 7 will be described below with reference to FIG.

FIG. 4 shows a detailed block diagram of the supervisory control device according to an embodiment of the present invention.

In the figure, terminals 101, 201, 511, 521 ... 5n1 are respectively connected to the transformer PT and current transformer CT101, 201, 511, 521 ...
It shows that it is connected to 1,32,45,46.

102,202,452 receives the secondary voltage of the transformer PT101,201,451,
This is a voltage converter that converts this into a DC voltage.

312a and 322a are power converters that receive a DC voltage proportional to active power by inputting the voltage of transformers PT101 and 201 and currents of current transformers CT31 and 32, and 312b and 322b are also proportional to reactive power when receiving inputs. A reactive power converter that obtains a DC voltage, 462 is a reactive power converter that also receives the secondary voltage and current of the transformer PT45 and current transformer CT46 as inputs.

In addition, 512 ... 5n2 are transformer PT201, current transformer CT511,521 ... 5n1
This is a power flow converter that receives the secondary output of ## EQU1 ## and outputs an instantaneous voltage value proportional to e + ki, e-ki in order to derive the active current and reactive current. The operation of the circuit after receiving this output measures various electric powers as described later.

Next 103,203,313a, 313b, 323a, 323b, 453,463,513,523… 5
n3 is a sample and hold amplifier, and each of the converters 102, 202, 312a, 312b, 322a, 322b, 452, 462, 512, 522 ... 5n2
Output (however, 2 types for 512 ... 5n2 each) are stored and held, and the timing is given from the microcontroller 6. 49 is a multiplexer,
The sample and hold amplifiers 103, 203, 313a, 313b ... 513 ...
The 5n3 output is sequentially switched and added to the A / D converter 50.

Reference numeral 50 denotes an A / D converter which receives the output of the multiplexer 49 and converts it into a digital value.

A reference numeral 60 denotes a micro controller (unit), which internally has a micro processor, an input / output port, a timer, a memory, etc., and receives an output signal of the A / D converter 50 to perform an operation and a judgment as shown in a function described later. , Display, output, etc. are processed.

Reference numeral 70 denotes a read-only memory (ROM), which stores a numerical table, data, etc. necessary for the arithmetic determination process performed by the microcontroller 60, and reads them from the ROM 70 as needed to reduce the processing load of the microcontroller 60.

Various converters V, P, Q, CONV, sample hold amplifier SH, multiplexer MPX49, A / D converter 5 in the above description
0, the microcontroller 60, the ROM 70, the power distribution boards 81 and 82 for the power interface, and the information transmission device 9 for the signal interface are known and commercially available except for those described below, and thus detailed description thereof is omitted. To do.

The power flow converter, which is a 512 ... 5n2 converter, is a passive static circuit (mainly composed of a transformer) that receives the transformer PT secondary voltage and CT secondary current as its output, and its output is e ₁ = e + ki e ₂ = e + ki However, Results in two alternating current outputs.

Various outputs are obtained by performing the following processing on these two outputs. The processing is done by the microcontroller 60.
Done inside.

First, the wave phase power is obtained as e _W = e ₁ ² + e ₂ ² = (e + ki) ² − (e−ki) ² = 4kei w = | ew | = 4k | ei |.

next, And the effective current is obtained.

By multiplying this by E (secondary side bus voltage) obtained by integrating the output of the voltage converter 202, the active power P can be obtained as follows.

P = E · e _D = 2kEIcos Further, if the active power P is found, the reactive power Q is found as follows.

The table required for the above calculations is stored inside the ROM70,
The operation result can be obtained by relating the argument to the address and accessing the corresponding address.

Therefore, the power flow converters 512 to 5n2 are the sample hold amplifiers 513 ... 5n3, the multiplexer 49, the A / D converter 50,
In combination with the microcontroller 60, the function of digital principle conversion / arithmetic is fulfilled, and all feeder loads W, active power P and reactive power Q from each feeder can be measured and detected respectively.

Next, the operation of FIG. 4 will be described with reference to the flowchart of FIG.

However, steps ST1 to 5 are measuring means, and steps ST6 to 11
Is a margin value calculating means, step ST12 is safety determining means, steps ST13 to 17 are first controlling means, step ST18 is safety determining means, and steps ST19 to 23 are second controlling means.

First, the high-voltage power supply system 1 is always operated as shown in the operating principle.
Bus voltage V, reactive power flow Q, as high voltage system side bus
The bus voltage V of 10 and the reactive power flow Q flowing into the transformer bank 3 are detected.

Generally, it is hard to say that the direction of the tidal current is always constant in the high-voltage power supply system 1, but here, the interconnection state with the low-voltage power supply system connected via the transformer bank 3 is measured, and the high-voltage side Grasp as one power supply system. These are measured by the converters 102, 312a, 312b.

Next, the low-voltage power supply system 2 first measures the power flow and voltage passing through the transformer bank 3 using the converters 202, 322a, 322b in FIG. 4, and measures the voltage and reactive power flow on the tertiary side of the transformer bank 3. Is measured using sample hold amplifiers 453 and 463.

In addition, the net load of the feeder 51 ... 5n various currents Wi, Pi, Qi
For (i = 1 to n), the power flow converters 512 ... 5n2 are used and measured by the method described in the section of configuration (step ST2).

Such measurement / conversion is executed for an appropriate cycle to accumulate data (step ST3).

High-voltage and low-voltage power supply systems 1, 2 by the steps ST1, ST2
The change amounts ΔV and ΔQ of the voltage and power flow components and ΔW, ΔP and ΔQ of the low-voltage side power system feeder are calculated (steps ST4 and ST5).

After knowing the changed amount, first, the power supply reactance x _g1 in the high-voltage power supply system 1 and the power supply reactance x _g2 in the low-voltage power supply system 2 are calculated. The method is the Japanese Patent Application Sho6.
2-234970 (JP-A-1-81623) and Japanese Patent Application No. 62-255313
No. 3, since it is disclosed in Japanese Patent Laid-Open No. 1-99435.

Next, the respective changes ΔV, Δ measured in the secondary load system
From Wi, ΔPi, ΔQi, etc., the impedance Z of the system viewed from the power supply side, its power factor angle, and the short-circuit capacity S are calculated. These values can be confirmed by using the reactances x _g1 and x _g2 of the power flow passing through the transformer bank 3 and the reactances of the system behind the upper and lower busses, which are obtained from the voltage changes on both the primary and secondary sides. .

At the same time, the load power factor cos θ is calculated for all feeder loads W and each feeder load W ₁ , W _2, ... W _n . The power factor angle θ is known from this value (step ST7).

From each of the above data, the power flow w ₁ ... W _{n of} each feeder converted to the system short-circuit capacity base, and the voltage v _{LL of} each feeder converted to the infinite bus voltage base are calculated (step ST8).

The maximum power w _m of the voltage stability limit and the bus voltage v at that time are calculated by using the well-known relational expression cited in the prior application (Reference, Technical Report of the Institute of Electrical Engineers of Japan (Part II), No. 73, pages 51 to 52). _Lm determines (step ST9).

Flow of each of these feeders w, w _m , voltage of each feeder v _L , v _Lm
(If necessary, the same value (w _j ,
From w _jm , v _Lj , v _Ljm ), the current flow w of each feeder with respect to the voltage stability limit, and the safety margins m _w , m _vL of the voltage v _L of each feeder can be obtained (m _wj , m _vLj are also obtained). These margins are compared with the security index of the grid operation that is obtained in advance by offline calculation to determine whether the margin is stable or unstable (steps ST10 to ST12).

The details of this index include human judgment, so it will not be discussed.

Next, if the current power flow vs. voltage status of each feeder with respect to this security index is not satisfied, it is necessary to adjust the reactive power supply, but the reactive power supply requirement for the voltage drop is described in the cited document (Technical Review of the Institute of Electrical Engineers of Japan). Report (II
Part), No. 73, pages 51-52). In particular, if it is also necessary to confirm the voltage stability at the substation bus at the other end of the drawer feeder, use the safety margins m _wj and m _vLj obtained at each feeder end in the above method to make a stable determination, and adjust the voltage vs. reactive power accordingly. Adjustment of·
Sometimes it controls.

The surplus amount is calculated by comparing the required reactive power amount obtained above and the available phase-modifying facility capacity (step ST13).

If there is a margin as a result, a breaker opening / closing command is output from the monitor control device 7 to operate the self-phase adjusting equipment and supply reactive power (steps ST14, ST15).

Further, if it is determined that the capacity of the self-phased equipment is insufficient as a result of the calculation of the surplus amount, the electric station outside the self-site is notified and the necessary support situation is notified (step ST16).

After operating the above reactive power supply equipment, the induced voltage V, active power P, reactive power Q, and total feeder load W of the ideal transformer of the grid are measured by the same method as steps ST1 and ST2, and the voltage stability limit is met. It is determined whether or not the margin index (m _w m _vR, etc.) has been sufficiently improved (step ST18).

If sufficiently improved, the following high voltage power system V / Q
Move on to operation. If not sufficiently improved, the process returns to the system reactance identification operation to confirm the system condition again (step ST18 → step ST6 forward rotation).

After the margin for the voltage stability limit is secured, the induced voltage V and reactive power Q of the ideal transformer in the high-voltage and low-voltage power systems are adjusted more precisely.

First, the tap changer 30 during load and the phasing equipment 4 are operated to generate the winding ratio change Δn and the reactive power supply pendant Δq, and the changes in V and Q caused by these changes, that is, the primary And the secondary system bus voltage ΔV _t1 and ΔV _t2 are measured, and then the reactances x _g1 and x _{g2 of the} system behind the upper and lower bus lines are calculated from equations (1.2), (1.3), (1.4) and (1.5). Is identified (step ST20).

Since the primary and secondary leakage reactances x _t1 and x _t2 are the reactances inside the transformer, they are measured in advance and treated as constants. The details of this method are the same as those in step ST6, and since they are known in Japanese Patent Application No. 57-173464, they are not described here.

Using the x _g1 , x _g2 , and x ₀ obtained as described above, when the voltage changes ΔV _g1 and ΔV _g2 behind the system are generated, the required operation amount winding ratio change Δn and the reactive power supply change Δq are calculated. However, in order to secure a margin index for the voltage stability limit of the lower load system,
First, after operating the phasing equipment 4, with this state as a reference,
The operation of Δn and Δq is performed so as to suppress the VQ target value of a predetermined upper system (steps ST21 and ST22).

As a result, if V and Q reach a region satisfying the predetermined dead zone range, the process ends, and the next constant measurement period is awaited. if,
If it does not fall within the region that satisfies the predetermined dead zone range due to poor adjustment, the process returns from the estimation of the limit of voltage stability to the first measurement operation (step ST1).

〔The invention's effect〕

As described above, according to the present invention, in an electric station connected to a high-voltage power system, the high-voltage power system is monitored and controlled by the monitoring control device for voltage stability at the low-voltage power system and the load inlet of the load substation. Since it is possible to perform voltage / reactive power control that is connected to the control system, it is possible to control the voltage / reactive power in a heavy load system by following load changes with high stability and high accuracy.

Moreover, since the system status is monitored and controlled by the supervisory control device, it is not necessary to transmit online the system status real-time data for measurement, monitoring and control to the supervisory control point, and the whole system is simple. There is an effect that is converted. However, if the above-mentioned data collected and confirmed at the electric station located on the higher voltage side can be easily obtained, the calculation judgment described in the above-mentioned operation including these is performed, and the result is more reliable. It goes without saying that things can be done.

[Brief description of drawings]

1 is an explanatory view of the principle according to an embodiment of the present invention, FIG. 2 is an explanatory view of an object to which the present invention is applied, FIG. 3 is a detailed configuration view showing an embodiment of the present invention, and FIG. FIG. 5 is a block diagram of the supervisory control apparatus shown in FIG. 5, and FIGS. 5A to 5C are flowcharts showing the specific operation of the present invention. In the figure, 1 is a high voltage current system, 2 is a low voltage power system, 3 is a transformer bank, 4 is a phase adjusting equipment, 10 is a high voltage system side bus, 20 is a low voltage system side bus, 7 is a supervisory control device, 30 Is tap changer at load, 31,51 to 5n, 46, 32 are current transformers, 101, 20
1,45 is a transformer, 81,82 is a (first and second) switchboard, 9 is an information transmission device, 41 is a branch reactor, 42 is a static capacitor, 43,44 is a circuit breaker, 49 is a multiplexer, 50 Is an A / D converter, 60 is a microcontroller, 102,202,452 voltage converters, 312a, 322a are power converters, 312b, 322b, 462 are reactive power converters, 512,522-5n2 are power flow converters, 103,313a, 3
13b, 203, 323a, 323b, 453, 463, 513, 523-5n3 are sample-hold amplifiers. In the figure, the same parts are designated by the same reference numerals.

Claims (1)

[Claims] 1. A voltage and power flow of a high-voltage power supply system, a voltage and power flow of a low-voltage power supply system, and a voltage on the tertiary side and low-voltage load feeder side of a transformer bank connecting the high-voltage power supply system and the low-voltage power supply system, Measuring means for measuring the amount of change in the power flow respectively, and based on the measurement results of the measuring means, the reactances of the high-voltage power supply system and the low-voltage power supply system are provisionally identified, and the reactance of the power supply system as seen from the load system is provisionally identified. Then, the normalized flow and the power stability limit for each feeder are calculated using the reactance and the load side power flow measurement results, and the margin value of the standardized flow for the power stability limit is calculated for each feeder. Stability discrimination for discriminating safety by comparing the margin value of each feeder calculated by the value arithmetic means and the margin value arithmetic means with each reference value And the safety discriminating means discriminates that there is no safety, the phasing equipment is controlled on the basis of the margin value for each feeder and the respective reference value, and the reactance is provisionally identified again. Before and after the control means and the first control means are controlled, the reactance is determined when the safety is confirmed by the safety determination means, and the tap value of the transformer and the phasing equipment are planned. And a second control means for finely adjusting the voltage / reactive power by controlling the voltage / reactive power.