JP2003174725A - Distribution system voltage control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage control method which can utilize existing voltage control apparatuses such as an SVR, etc., effectively at a low cost without being troubled by countermeasures against heat, noise, etc. <P>SOLUTION: This voltage control method controls a voltage value of a distribution system, to which first and second voltage control apparatuses are connected, to be within a prescribed range. For instance, this voltage control method suppresses the fluctuation of the system voltage which is caused by the output fluctuations of distributed power supplies DG connected to the distribution system. A series/parallel-type united power flow controller (UPFC) 500 is used as the first voltage control apparatus and, if the voltage value of the distribution system is stepped out of the prescribed range, the voltage is compensated by the UPFC 500 first and then the compensation value is gradually reduced by compensating the voltage command value and the reduced compensation value is transferred to an SVR 600, which is the second voltage control apparatus, for compensation. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a unified power flow controller for controlling voltage fluctuations occurring in a distribution system.
ow Controller: UPFC) for a voltage control method for compensation by operation.

[0002]

2. Description of the Related Art As a device for compensating for voltage fluctuations occurring in a distribution system, a tap type voltage control device (Step Voltage Regulator: SV) has been conventionally used.
R) is used. Conventionally, a distribution system has been operated and controlled based on a system plan on the assumption that power flow flows in one direction in a radial system extending from a distribution substation toward a load end. However, with the progress of deregulation in recent years, it is expected that a large number of distributed power sources will be connected to the distribution system, which may cause reverse power flow in the distribution system.

Conventional power distribution system management / operation methods and control techniques are based on the assumption that there is no reverse power flow, and when distributed power sources are introduced, problems such as the system voltage deviating from the voltage management range may occur. It is possible that it will occur. Also,
When distributed power sources that generate steep output fluctuations, such as wind power generators, are connected, the existing SVRs are intended for compensation of load fluctuations on the order of minutes, so the It cannot respond to voltage fluctuations.

The above problem will be described in detail below with reference to the drawings. FIG. 13 is a diagram schematically illustrating a distribution system in which distributed power sources DG are interconnected, and 100 is a distribution substation or SV.
R indicates a tap type voltage control device. In FIG. 13, FIG. 14 shows a voltage profile when the distributed power source DG is constantly performing the rated output operation.

If there is no distributed power source DG, the distribution substation 1
Although the grid voltage decreases as the distance from 00 increases, the distributed power supply DG performs the rated operation, so a reverse power flow occurs due to the distributed power supply DG in the distribution system, and the grid voltage changes to that of the distributed power supply DG. From the point where the reverse power flow has reached, it starts to rise. If there is no SVR, this reverse flow causes
As indicated by the broken line, there is a possibility that a voltage constraint violation with respect to the voltage upper limit may occur near the point where the distributed power source DG is connected to the power distribution system. However, when there is an SVR in the system as shown in FIG. 13, by operating the tap, as shown by the solid line in FIG. 14, in the section downstream from the SVR installation point (direction away from the distribution substation 100). Since the voltage drops, deviation from the voltage constraint is prevented. That is, the system voltage can be constantly compensated by the SVR, and the occurrence of voltage constraint violation can be prevented.

Here, considering a case where a transient change in which the output of the distributed power source DG becomes zero occurs from the steady state shown in FIG. 14, the voltage profile is as shown in FIG. Since the output of the distributed power source DG has become zero, the system voltage decreases as the distance from the distribution substation 100 increases. Therefore, in the downstream section of the system, the voltage constraint may deviate from the lower voltage limit. The SVR cannot respond to such an instantaneous voltage fluctuation, and responds with a certain time constant (usually a minute level). That is, the SVR which is the existing voltage control device alone cannot cope with the instantaneous output fluctuation of the distributed power source, and the system voltage cannot be maintained within the predetermined range.

Further, in recent years, as a device for compensating for an instantaneous voltage fluctuation, a voltage control device (hereinafter referred to as a power electronics device) to which power electronics technology is applied has been attracting attention. This type of power electronics device can normally perform voltage compensation in the order of several tens of ms, and the distributed power source DG as described above is used.
It is possible to compensate for the instantaneous voltage fluctuation caused by the output fluctuation. However, if the voltage is compensated only by the power electronics device, the existing SVR becomes unnecessary, and there is a problem that the existing device cannot be utilized. Further, if it is attempted to compensate the voltage only with the power electronics equipment, the power electronics equipment must always be operated so as to be able to compensate the voltage, so that heat countermeasures and noise countermeasures for the device are required. Further, since the device capacity also increases, there is a problem that the manufacturing cost of the power electronics device increases.

Therefore, the present invention intends to provide a voltage control method which is low in cost, does not have to be troubled by heat countermeasures, noise countermeasures, and the like, and can effectively utilize existing voltage control equipment such as SVR. It is a thing.

[0009]

In order to solve the above problems, the invention according to claim 1 is a voltage control for controlling a voltage value of a power distribution system to which a first voltage control device and a second voltage control device are connected within a predetermined range. A voltage control method for suppressing fluctuations in a system voltage caused by, for example, fluctuations in output of a distributed power source connected to a distribution system, wherein a series compensating unit and a parallel compensating unit are used as a first voltage control device. In the voltage control method using the integrated power flow controller having the above, when the voltage value of the distribution system deviates from a predetermined range, first, the integrated power flow controller performs voltage control, and then the voltage of the integrated power flow controller. The command value is corrected to gradually reduce the voltage compensation amount, and the reduced voltage compensation amount is transferred to the second voltage control device for compensation.

According to a second aspect of the present invention, in a voltage control method for controlling a voltage value of a distribution system within a predetermined range by a total power flow controller having a series compensation unit and a parallel compensation unit, the parallel compensation unit is a power distribution unit. It is characterized in that two voltage command values can be set according to the rise or fall of the voltage value of the system.

According to a third aspect of the present invention, in a voltage control method for controlling a voltage value of a distribution system within a predetermined range by a total power flow controller having a series compensation unit and a parallel compensation unit, the series compensation unit is a power distribution unit. It is characterized in that two voltage command values can be set according to the rise or fall of the voltage value of the system.

According to a fourth aspect of the present invention, in a voltage control method for controlling a voltage value of a distribution system within a predetermined range by a total power flow controller having a series compensation unit and a parallel compensation unit, the total power flow controller includes: For example, the parallel compensating unit extracts a flicker component included in the system voltage and performs a control operation according to a voltage command value that cancels the flicker component.

The invention according to claim 5 corresponds to the invention in which the above claims 1 to 4 are combined, and the voltage value of the power distribution system to which the first and second voltage control devices are connected is within a predetermined range. And a series compensating unit capable of setting two voltage command values in accordance with a change in the voltage value of the distribution system, as a first voltage control device, and When a voltage value of a distribution system deviates from a predetermined range by using a total power flow controller that extracts a flicker component included in a system voltage and performs a control operation according to a voltage command value that cancels the flicker component, Voltage control is performed by the integrated power flow controller, and then
The voltage command value of the integrated power flow controller is corrected to gradually reduce the voltage compensation amount, and the reduced voltage compensation amount is transferred to the second voltage control device for compensation.

According to a sixth aspect of the present invention, in the invention according to the fifth aspect, by using an existing tap type voltage control device (SVR) as the second voltage control device, a series-parallel type integrated power flow control is performed. The voltage of the distribution system is controlled by the coordinated control of the device and the SVR.

According to a seventh aspect of the invention, in the voltage control method for a distribution system according to the sixth aspect, the voltage command value of the integrated power flow controller is corrected to gradually reduce the voltage compensation amount. This is to operate the SVR by removing the monitoring point voltage of the SVR on the power distribution system from the dead zone of the SVR.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment corresponding to the invention described in claims 1, 6 and 7 will be described. FIG. 1 is a diagram schematically illustrating a power distribution system to which this embodiment is applied, and a UPFC 500 as a first voltage control device is connected between sections 5 and 6 of the power distribution system. 60
Reference numeral 0 is the SVR as the second voltage control device connected between the sections 4 and 5.

Here, the UPFC 500 controls the phase and amplitude of the power transmission and distribution system to adjust the power flow, suppress power fluctuations, stabilize the voltage, and the like by using FACTS (Flexible AC Tran).
smission system) is a type of equipment that is capable of controlling system power directly and at higher speed than conventional power conditioning equipment.

FIG. 2 is a block diagram showing an example of a series-parallel UPFC 500, which is a parallel compensator (parallel inverter) 202 connected in parallel to a distribution system via a transformer 201.
And a series compensator (series inverter) 302 connected in series via a transformer 301, and the direct current sides of these compensators 202 and 302 are connected by a capacitor 230. In addition, 203 and 303 are PWM circuits, and 400 is a digital signal processor (DSP). In the present embodiment, a parallel static var compensator (Stat
ic Var Compensator (SVC), and it was decided to use a series-parallel type UPFC, which allows a smaller capacity. Note that U
Regarding the sharing of compensation for the PFC 500, the system upstream of the UPFC installation point is assigned to the parallel compensator 202, and the system downstream is assigned to the series compensator 302.

In this embodiment, when the output of the distributed power source DG changes and an instantaneous voltage fluctuation occurs in the system, the UPFC 500 first performs a voltage compensation operation, and the compensation amount is gradually reduced. By that, SVR 60
By tapping 0, part of the voltage compensation amount initially shared by the UPFC 500 was transferred to the SVR 600.

Next, an outline of the voltage compensation operation is shown in FIG.
In FIG. 3, the maximum output of the distributed power source DG (voltage profile shown in the figure) at first becomes zero (voltage profile shown in the figure), and finally the UPFC
The state (voltage profile shown in the figure) in which the voltage is compensated by 500 is shown. Voltage is compensated by the parallel compensator 202 by the UPFC 500 installed between the sections 5 and 6, that is, the upstream system at the UPFC installation point and by the series compensator 302 on the downstream system, and the voltage profile of No voltage constraint deviation has occurred.

However, since the UPFC 500 continues to perform voltage compensation in this state, the compensation amount by the UPFC 500 does not shift to the SVR 600. That is, S
As shown in FIG. 3, the VR 600 has a voltage monitoring point based on the set value of the SVR installation point as a reference, and when the monitoring point voltage is in the dead zone of the SVR, the SVR cannot perform the tap operation. In order for the SVR to perform the tap operation, it is necessary to remove the monitoring point voltage from the dead zone.

In the voltage profile of FIG. 3,
As a result of voltage compensation by UPFC 500, SV
The monitoring point voltage of R 600 has entered the dead zone,
As it is, the tap operation of the SVR 600 is not performed. Therefore, by operating the tap of SVR 600, UP
In order to shift the voltage compensation amount by the FC 500 to the SVR 600, it is necessary to remove the monitoring point voltage of the SVR 600 outside the dead zone. Therefore, in the present embodiment, the UPF
Correct the voltage command value of the parallel compensating unit 202 of C 500,
Reduce the amount of voltage compensation of the UPFC 500. This state is shown in FIG.

In FIG. 4, the SVR monitoring point voltage is initially SVR 60 because there is compensation by UPFC 500.
It is within the dead zone of 0 (voltage profile shown in the figure). However, in this state, if the voltage command value of the parallel compensating unit 202 of the UPFC 500 is corrected and the voltage compensation amount of the UPFC 500 is gradually decreased, the voltage on the upstream side of the UPFC 500 gradually decreases, and thereafter, The SVR monitoring point voltage will fall outside the dead band of the SVR 600 (voltage profile shown in the figure).

If the monitoring point voltage of the SVR 600 deviates from the dead zone as described above, the tap operation of the SVR 600 becomes possible and the voltage on the downstream side of the SVR 600 increases, so that the compensation amount of the UPFC 500 decreases. Become.
That is, a part of the voltage compensation amount by the UPFC 500 shifts to SVR. Note that the above example relates to the time of voltage drop, but the same method can be applied to the time of voltage rise.

Next, a second embodiment corresponding to the invention of claim 2 will be described. Normally, the parallel compensating unit of the UPFC has one voltage command value and operates so as to match the system voltage with the voltage command value. This state is shown in FIG.

FIG. 5A shows the voltage command value of the parallel compensator.
V_C ^*Is set between the upper and lower limits of the voltage constraint.
It is the case. At this time, the current voltage is the voltage command value V_C ^*Yo
When larger (V in the figure₁), UPFC is ΔV₁= V₁−
V_C ^*Compensating for the voltage ₁To V_C ^*Trying to get closer to
To do. In addition, the current voltage is the voltage command value V_C ^*Less than
Case (V in the figure_Two), UPFC is ΔV_Two= V_C ^*-V_TwoNa
Compensating for the voltage_TwoTo V_C ^*Try to get closer to. Na
The voltage command value has a voltage constraint as shown in (2) of FIG.
Set it to a value other than the middle of the upper and lower limits (in this case,
Pressure command value is V_n ^*UPFC is also possible.
Is ΔV₁’= V₁-V_n ^*Or ΔV_Two’= V_n ^*−
V_TwoCompensate for the voltage.

However, as shown in (2) of FIG. 5, when the voltage command value V _n ^* is set to be larger than the intermediate value between the upper and lower limit values of the voltage constraint, the compensation voltage ΔV for the voltage compensation for V _{1 is} set. _{1 'but} it can be smaller than the [Delta] V ₁ in FIG. 5 (1), the voltage compensation for V ₂ the compensation voltage Δ
V ₂ ′ becomes larger than ΔV ₂ in FIG. 5 (1). Therefore, when only one voltage command value is set, normally,
Make sure that there is no bias in the compensation voltage in both directions.
The voltage command value is set in the middle of the voltage constraint upper limit value and lower limit value as shown in FIG.

[0028] However, setting the voltage command value _V ^{C *} in the middle between the voltage limitations upper limit value and the lower limit value, the compensation capacitance is at a maximum (voltage constraints limit _-V ^{C *)} or _(V ^{C *} -
It becomes the voltage constraint lower limit value) and becomes large. On the other hand, by setting two voltage command values in the upper and lower directions within the upper and lower limit range of the voltage constraint, the compensation capacity can be made smaller than in the case where the voltage command value is one. This state is shown in FIG.

FIG. 6 (1) is substantially the same as FIG. 5 (1) and shows the case where the voltage command value V _C ^* is set between the upper limit value and the lower limit value of the voltage constraint. On the other hand, the voltage command value is two as shown in FIG. _{6 (2) (V C *} +, V C * -) some cases, the first voltage command value V at the time of voltage rise close to the voltage constraints limit
Select _{C *} ^+, at the time of voltage drop the second voltage command value V _{C *} is close to the voltage constraints limit value ^- selecting.

[0030] In this case, 'to compensate for ₌ V 1 _-V ^{C * +} becomes voltage, for the voltage _{V 2} at the time of voltage drop [Delta] V _2' [Delta] V ₁ is the voltage _{V 1} of the time of voltage increase = V _C ^* - to compensate for the -V ₂ becomes voltage. At this time, the compensation voltage ΔV ₁ ′, Δ
V ₂ 'is the compensation voltage Δ when there is only one voltage command value
Both can be made smaller than V ₁ and ΔV ₂ . That is, if the two voltage command values can be set so as to cope with the voltage rise and the voltage fall, the device capacity can be reduced, and the overall size and cost of the device can be reduced.

Next, a third embodiment corresponding to the invention of claim 3 will be described. In the second embodiment described above, the UPFC
The parallel compensating unit 202 of 500 has two voltage command values V _C
^* _{+, V} ^{C * -} but it is for setting a series part 3
By similarly setting two voltage command values for 02 as well, it is possible to reduce the capacity of the device and realize the downsizing and cost reduction of the entire device.

Next, a fourth embodiment corresponding to the invention of claim 4 will be described. For example, when the wind turbine generator is connected to the power distribution system, a slight change in output occurs due to the tower shadow effect. The tower shadow effect is such that when the blades of the wind turbine enter the shadow of the tower that supports the wind turbine, the output is slightly reduced, and this cycle is close to 1 Hz, which may cause flicker. On the other hand, a power electronics device such as UPFC can respond for several tens of ms, and can respond faster than the flicker cycle. That is,
It is possible to suppress this flicker by power electronics equipment.

In order to suppress the flicker by UPFC, the flicker component may be extracted and the voltage may be compensated in the opposite direction to the flicker component. This flicker component extraction method is shown in FIG. When a flicker is superimposed on the steady component of the system voltage as shown in FIG. 7, the flicker component is removed by passing through a first-order lag filter 700 having a time constant sufficiently larger than the time constant of the flicker. Only the stationary component is extracted (FIG. 7). Therefore, it is possible to extract only the flicker component by taking the difference with (FIG. 7). UP to offset this flicker component
Flicker can be suppressed by creating a voltage command value for the FC parallel compensator or series compensator.

Next, a fifth embodiment corresponding to the invention of claim 5 will be described. This embodiment relates to a voltage control method that integrates the above-described first to fourth embodiments, and maintains the voltage within a predetermined range when a power source such as a wind turbine generator that causes a steep output change is connected. In addition, the device capacity can be reduced, and flicker of the system voltage can be suppressed.

The compensation characteristics of this embodiment are shown in FIG. Figure 8
Areas and areas shown in are up-converted by steep voltage fluctuations.
There is a possibility that the voltage constraint may be exceeded both upstream and downstream of the installation point of
In some cases, the parallel compensating unit 202 may be installed at the UPFC installation point.
In order to compensate the voltage on the upstream side, when the voltage is in the
Pressure command value V _pmax, The voltage command value V
_pminTake Where V_pmaxIs a steep voltage rise
Sometimes the minimum required to maintain the upstream voltage at the specified value.
Voltage command value, V_pminIs high when the voltage drops sharply.
The minimum voltage voltage required to maintain the source voltage at the specified value.
It is an official price.

As described above, the parallel compensator 202 switches between the two voltage command values according to the magnitude of the system voltage according to the second embodiment. At the same time, the parallel compensator 202 uses the UPFC
In order to partially shift the compensation by 500 to the SVR 600, it also has a correction function of the voltage command value described as the first embodiment.

The series compensator 302 compensates the voltage downstream of the UPFC installation point by setting the voltage command value V _smax when the voltage is in the region and the voltage command value V s when the voltage is in the region.
take a _{smi n.} Here, V _smax is a minimum required voltage command value for maintaining the downstream voltage at the specified value when the voltage rises sharply, and V _pmin is for maintaining the downstream voltage at the specified value when the voltage drops sharply. It is the minimum required voltage command value. As described above, the series compensation unit 302 switches between the two voltage command values according to the magnitude of the system voltage, as described in the third embodiment.

Areas and areas shown in FIG. 8 are cases where there is a possibility that the voltage constraint may deviate on the downstream side of the UPFC installation point due to a sharp voltage increase or voltage drop. On the upstream side, there is no possibility of voltage constraint deviation due to the voltage command values V _pmax and V _pmin, so that the parallel compensating unit 202 operates the flicker suppressing function of the fourth embodiment. Series compensation unit 30
In order to compensate the voltage on the downstream side of the UPFC installation point, 2 takes the voltage command value V _smax when the voltage is in the region and the voltage command value V _smin when the voltage is in the region. That is, the series compensation unit 302 has the same voltage command value V in the area.
_smax is taken and the same voltage command value V
Take _smin .

Further, the region shown in FIG. 8 is a case where there is no possibility of voltage constraint deviation both upstream and downstream of the installation point of the UPFC, and in this case, the flicker suppressing function of the parallel compensating unit 202 is activated.

Finally, a sixth embodiment corresponding to the invention of claim 6 will be described. This embodiment relates to the voltage control by the existing SVR and the cooperative control method according to the fifth embodiment. That is, by the cooperative control of the SVR and the UPFC according to the fifth embodiment, the UPFC shares the steep voltage fluctuation of the system and the SVR shares the steady voltage fluctuation, thereby preventing the occurrence of the voltage constraint deviation. did.

In order to realize the cooperative control by SVR and UPFC, it is necessary to correct the voltage command value of the parallel compensator described as the first embodiment. The correction flow is shown in FIG. That is, the voltage command value of the parallel compensator 202 of the UPFC 500 is corrected by the following procedure, and the SVR 60
0 and UPFC 500 perform cooperative control.

Step S1: Detection of the installation point voltage of the UPFC 500 The installation point voltage V _det of the UPFC 500 is detected.

[0043] Step S2, S3: determining established by the magnitude relationship between the voltage command value as shown in point voltage _{V det} and 8, which region the voltage _{V det} (uncompensated region of the compensation pattern, series compensation region, straight The compensation pattern is determined by detecting whether it belongs to the parallel compensation area). When the voltage _Vdet is in the region of FIG. 8 and there is no compensation (S21), the voltage command value is left uncorrected. In other cases, if the voltage V _det is in the region of or in FIG. 8, it is determined that only the series compensation is performed and the voltage command value V is determined.
Set _sref to example _{V smax} or _{V smin} (S31), performs voltage compensation by series part 302 (S32). It should be noted that during non-compensation (S21) and during voltage compensation by the series compensation unit 302 (S32), the flicker suppressing operation by the parallel compensation unit 202 described as the fourth embodiment is performed.

Step S4: Serial compensator 302 and parallel
Setting of each control parameter of the column compensator 202 In step S3, the series compensation unit 302 and the parallel compensation unit
When it is determined that voltage compensation by both 202 is necessary
(Region in FIG. 8) indicates the assumption of serial-parallel compensation.
And the voltage V_detOf UPFC 500 where there is a
Based on the area, the series compensator 302 and the parallel compensator in advance.
Each control parameter of 202 (voltage command value V _ref, Invalid
Current steady value I_qref, Voltage command value correction gain K, etc.)
Set. Here, the correction gain K is the reactive current of the system.
It is related to the response time of control to make it a steady value, and SVR
Set in advance based on the tap operation time limit.

Steps S5 and S6: UPFC 500
The parallel compensator 202 and the series compensator 302 of
Compensate the voltage of the upstream system and downstream system of the FC installation point.

Step S7: Detection of reactive current I _{q In} order to obtain a voltage command value correction value which will be described later, UPFC
The parallel compensating unit 202 of 500 detects the reactive current I _q injected into or absorbed from the system.

Step S8: Calculation of voltage command value correction value of parallel compensating section 202 Deviation ε (= between I _q detected in step S7 and steady state reactive current I _qref set in step S4
I _q −I _qref ) is integrated, and step S
By multiplying the voltage command value correction gain K set in 4, the voltage command value correction value ΔV _pref as the compensation voltage to be transferred to the SVR 600 is obtained. That is,
Calculate ΔV _pref = K · ∫εdt.

Steps S9 and S10: parallel compensator 20
2. Correction of voltage command value of 2 and correction limiter The voltage command value of the parallel compensating unit 202 is corrected by adding ΔV _pref obtained in step S8 to V _pref (S
9). However, if the corrected V _pref reaches the upper limit value (lower limit value) of the correction range of the voltage command value, the voltage command value is fixed to the upper limit value (lower limit value) (S10). At the same time, the operation of the SVR 600 compensates the voltage corresponding to the voltage command value correction value ΔV _pref . After that, by repeating the operations in and after step S5 again, the voltage command value of the parallel compensating unit 202 is gradually corrected and the compensation voltage is gradually shifted to SVR 600.

[0049]

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 10 shows the configuration of a power distribution system to which the present invention is applied. The target system has a total length of 6.7 [km] equally divided into eight sections, and there is a load of the same size at the end of each section. The SVR 600 is 3.61 [km] from the transmission power source (corresponding to the distribution substation 100), and the UPFC 50
0 is installed at a position of 5.155 [km] from the power supply for transmission. The distributed power source DG is installed at the end of the system.

The applicable conditions are shown below. -Sending voltage: 6800 [V] assuming heavy load-Voltage limit value: Maximum voltage 6900 [V] Minimum voltage 6300 [V] -SVR voltage reference value: 6570 [V] -SVR dead zone: To voltage reference value ± 1.5 [%]-SVR settling R: 8.0 [%]-SVR settling X: 5.0 [%]-UPFC V _pmax : 688.76 [V] -UPFC V _smax : 6829.68 [ V] -UPFC V _smin : 6370.32 [V] -UPFC V _pmin : 6312.24 [V] -UPFC parallel compensating unit voltage command upper limit value: 6887.76 [V] -UPFC parallel compensating unit voltage command lower limit value: 6312.24 [V] -UPFC series compensation unit voltage command upper limit value: 6829.68 [V] -UPFC series compensation unit voltage command lower limit value: 6370.32 [V] Also, SVR The operation timed 00 is in the actual system the value of the partial order, the shorter simulation time, this time is set to 10 seconds.

In this system, a simulation was performed in which the output of the distributed power source DG changes like a ramp and a minute fluctuation (flicker) is superimposed on the change. Note that the lamp change is such that the output of the distributed power source DG that was initially in rated operation becomes zero in 10 seconds.
It seems to be the largest frequency band in a wind power generator 1 [H
z] (tower shadow effect), the fluctuation of 20% of the rated output is superimposed on the fluctuation of the lamp.

(1) When voltage control is performed by SVR alone Section 5 when voltage control is performed by SVR 600 alone
(Upstream representative of UPFC 500), Section 8 (UPFC
FIG. 11 shows the voltage transition of 500 downstream side representative).

From FIG. 11, it can be seen that, until the SVR 600 operates, the voltage in the sections 5 and 8 is below the voltage constraint lower limit value due to the output fluctuation of the distributed power source DG. Further, the voltage fluctuates due to flicker caused by the dispersed power source DG.

(2) When voltage control is carried out by cooperative control of SVR and UPFC Section 5 (upstream representative of UPFC 500), section 8 when voltage control is carried out by cooperative control of SVR 600 and UPFC 500 FIG. 12 shows the voltage transition (downstream representative of UPFC 500) and the transition of the compensation capacity of the parallel compensating unit.

From FIG. 12, first, the UPFC 500 operates the flicker suppressing function to suppress the flicker occurring in the system. When the grid voltage drops, UPFC
500 shifts to a cooperative operation to compensate for the drop in the system voltage. The parallel compensator of the UPFC 500 gradually corrects the voltage command value and reduces the compensation amount. UPFC 500
The monitoring point voltage of SVR 600 is SV
Since the dead zone of R 600 is exceeded and the SVR 600 reaches the operation time limit, the tap is activated and a part of the compensation amount of the UPFC 500 shifts to the SVR 600.
By repeating the above operation and finally operating the tap of the SVR 600, the compensation by the UPFC 500 will settle down to zero steadily.

[0056]

As described above, according to the present invention, cooperative control of a series-parallel integrated power flow controller and an existing voltage control device such as an SVR causes an increase in device capacity, heat countermeasures and noise. It is possible to provide a voltage control method that can effectively use an existing voltage control device at low cost without being bothered by measures or the like.

[Brief description of drawings]

FIG. 1 is a diagram schematically illustrating a power distribution system to which a first embodiment of the present invention is applied.

FIG. 2 is a configuration diagram of the UPFC in FIG.

FIG. 3 is a voltage profile showing the operation of the UPFC in the first embodiment.

FIG. 4 is a voltage profile showing the operation of the first embodiment.

FIG. 5 is an explanatory diagram of an operation in the second and third embodiments.

FIG. 6 is an explanatory diagram of an operation in the second and third embodiments.

FIG. 7 is an explanatory diagram of a flicker extraction principle according to the fourth embodiment.

FIG. 8 is a diagram showing a compensation characteristic of the fifth embodiment.

FIG. 9 is a flowchart showing a voltage compensating operation and a voltage command value correcting operation in the sixth embodiment.

FIG. 10 is a system configuration diagram showing an embodiment of the present invention.

FIG. 11 is a diagram showing a transition of the system voltage when voltage compensation is performed by SVR alone in the example of the present invention.

FIG. 12 is a diagram showing a transition of a system voltage and a compensation capacity of a parallel compensating unit in an example of the present invention.

FIG. 13 is a diagram schematically illustrating a distribution system in which distributed power sources are interconnected.

FIG. 14 is a diagram showing a voltage profile in FIG. 13 when the distributed power source is constantly performing rated output operation.

FIG. 15 is a diagram showing a voltage profile when a transient change in which the output of the distributed power supply becomes zero in FIG. 13;

[Explanation of symbols] 100 distribution substation 201,301 transformer 202 Parallel compensator 302 Series compensation unit 203, 303 PWM circuit 230 capacitors 400 DSP 500 UPFC 600 SVR 700 First-order lag filter

Continued front page    (72) Inventor Kayomi Hayashi             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd. (72) Inventor Shinichi Takayama             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Inside Fuji Electric Co., Ltd. (72) Inventor Yoshikazu Fukuyama             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Inside Fuji Electric Co., Ltd. (72) Inventor Hirokazu Tokuda             1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa             Within Fuji Electric Co., Ltd. F-term (reference) 5G066 DA01 DA07 DA08                 5H420 BB03 BB12 BB14 CC05 CC09                       DD04 DD09 EA27 EA29 EA30                       EA39 EA40 EB09 EB13 EB26                       EB39 EB40 FF03 GG01

Claims (7)

[Claims] 1. A voltage control method for controlling a voltage value of a power distribution system to which first and second voltage control devices are connected within a predetermined range, wherein the first voltage control device includes a series compensator and a parallel compensator. In the voltage control method using the integrated power flow controller having a section, when the voltage value of the distribution system deviates from the predetermined range, first the integrated power flow controller performs voltage control, and then the integrated power flow controller A voltage control method for a power distribution system, which corrects a voltage command value to gradually reduce the voltage compensation amount, and transfers the reduced voltage compensation amount to a second voltage control device for compensation. 2. A voltage control method for controlling a voltage value of a distribution system within a predetermined range by an integrated power flow controller having a series compensation unit and a parallel compensation unit, wherein the parallel compensation unit varies the voltage value of the distribution system. A voltage control method for a power distribution system, wherein two voltage command values can be set according to the above. 3. A voltage control method for controlling a voltage value of a distribution system within a predetermined range by an integrated power flow control device having a series compensation unit and a parallel compensation unit, wherein the series compensation unit varies the voltage value of the distribution system. A voltage control method for a power distribution system, wherein two voltage command values can be set according to the above. 4. A voltage control method for controlling a voltage value of a distribution system within a predetermined range by an integrated power flow controller having a series compensator and a parallel compensator, wherein the integrated power flow controller includes a flicker included in the grid voltage. A voltage control method for a power distribution system, wherein a component is extracted, and a control operation is performed according to a voltage command value that cancels the flicker component. 5. A voltage control method for controlling a voltage value of a power distribution system to which first and second voltage control devices are connected within a predetermined range, wherein the first voltage control device includes a voltage value of a power distribution system. It has a series compensator and a parallel compensator that can respectively set two voltage command values according to fluctuations, and controls according to a voltage command value that extracts the flicker component contained in the system voltage and cancels this flicker component. When the voltage value of the distribution system deviates from the specified range, the integrated power flow controller first performs voltage control by the integrated power flow controller, and then corrects the voltage command value of the integrated power flow controller. Then, the voltage compensation amount is gradually reduced, and the reduced voltage compensation amount is transferred to the second voltage control device to compensate for it. 6. The voltage control method for a power distribution system according to claim 5, wherein the second voltage control device is a tap type voltage control device. 7. The voltage control method for a power distribution system according to claim 6, wherein the voltage command value of the integrated power flow controller is corrected to gradually reduce the voltage compensation amount, and thus the tap type on the power distribution system is used. A voltage control method for a power distribution system, wherein a tap point voltage control device is operated by removing a monitoring point voltage of the voltage control device from a dead zone of the tap type voltage control device.