JP2006042546A - Automatic voltage regulator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic voltage regulator capable of regularly controlling a voltage on a load side according to a cause for generation of an adverse tidal current. <P>SOLUTION: This automatic voltage regulator includes a reverse-current relay 9 for detecting a direction of a power tidal current at a ground contact point of the automatic voltage regulator 1; a load 11 for measuring impedance, connected to a secondary-side distribution line of the automatic voltage regulator 1 when the adverse tidal current of an electric power is detected by the reverse-current relay 9; a first instrument current transformer 7 for detecting a current which flows to the secondary-side of the automatic voltage regulator 1; a second instrument current transformer 15 for detecting the current which flows to the load 11 when the load 11 is connected; and a distribution system state detector 13 for deciding a cause for the adverse tidal current from the impedance of a primary-side distribution system to the impedance of a secondary-side distribution system calculated on the basis of the change of the detected current with the second instrument current transformer 15 and the detected current with the first instrument current transformer 7 before and after the load 11 is connected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the automatic voltage regulator installed in the power distribution system, when a reverse power flow occurs in the automatic voltage regulator due to system switching of the distribution system or linkage with a distributed power source, the primary voltage regulator of the automatic voltage regulator Automatic voltage that can always adjust the voltage on the load side properly by immediately determining whether the power substation is connected to the secondary side or the secondary side, and accurately grasping the state of the distribution system Regarding the regulator.

  In the conventional distribution system, the condition that the power flow at the installation point of the automatic voltage regulator (hereinafter referred to as SVR) installed in the middle of the distribution line for the purpose of voltage control of the distribution line is a reverse flow is the system in the distribution system The substation connected to the primary side is connected to the secondary side by the switching operation of the distribution system, so that the SVR secondary side to the primary side are assumed. It has been thought that power is supplied toward

  However, in recent years, as private power generation facilities such as solar power generation devices have become widespread, these facilities have been linked to the distribution system as distributed power sources. As a result, even in a system where a substation exists on the primary side of the SVR, the power flow at the SVR installation point may be a reverse flow due to the relationship between the capacity of the distributed power source and the load capacity.

Some conventional SVRs have a configuration in which the secondary voltage is maintained at the target voltage when power is forwarded. This type of SVR is installed by switching the distribution system or linking distributed power sources as described above. When a reverse power flow occurs at a point, there is one in which a tap is fixedly controlled (see Patent Document 1).
Japanese Patent Publication No. 2-35326

  However, when this type of SVR is installed in the distribution system, if a reverse power flow occurs at the installation point of the SVR and the tap fixing control is executed, the occurrence of an abnormality in the voltage of the distribution system can be prevented. When the reverse power flow is caused by a distributed power source connected to the secondary side (such as when the output of the private power generation facility is larger than the load connected to the secondary side), the tap is fixedly controlled to There was a problem that the voltage adjustment operation of the load connected to the secondary side was stopped.

  In view of such problems, the present invention provides a substation on either the primary side or the secondary side of the automatic voltage regulator when a reverse power flow occurs at the installation point of the automatic voltage regulator installed in the distribution system. An automatic voltage regulator is provided that can determine whether or not a place and a load are connected and reliably perform load-side voltage adjustment at all times.

  According to the first aspect, in the automatic voltage regulator that automatically adjusts the load side voltage by the tap switching operation of the voltage regulating transformer by the on-load tap switching device installed in the middle of the distribution line, A reverse flow relay that detects the direction of the power flow at the installation point of the voltage regulator, and an impedance measurement unit that is connected to the distribution line on the secondary side of the automatic voltage regulator when the reverse flow is detected by the reverse flow relay A load, a first current transformer for detecting the current flowing through the secondary side of the automatic voltage regulator, and a second instrument current detecting for detecting the current flowing through the load when the load is connected. A primary current distribution system calculated based on a current detected by the current transformer and a change in the current detected by the first current transformer before and after connection of the load. Impedan When configured by comprising determining the distribution system condition detecting means cause the reverse flow from the ratio of the impedance on the secondary side distribution system.

  According to the second aspect, in the automatic voltage regulator that automatically adjusts the load side voltage by the tap switching operation of the voltage adjusting transformer by the on-load tap switching device installed in the middle of the distribution line, Connects to the distribution line via a reverse relay that detects the direction of the power flow at the installation point of the voltage regulator, and a step-down transformer that is excited by the voltage adjustment transformer when the reverse flow is detected by the reverse relay A load for impedance measurement, a first current transformer for detecting a current flowing through the secondary side of the automatic voltage regulator, and a current flowing through the load when the load is connected Calculated on the basis of a change in the detected current by the second instrument current transformer and the detected current by the first instrument current transformer before and after the connection of the load with the detected current by the second instrument current transformer From the ratio of the impedance of the impedance and the secondary side power distribution system of the next-side power lines were configured by including determining distribution system condition detecting means cause the reverse flow.

  According to a third aspect, in the first and second aspects, the distribution system state detection means includes switching means that is turned on / off according to the output signal, and according to the output signal of the reverse flow relay. By operating the switching means, the connection / disconnection of the load to the distribution line is switched.

  According to a fourth aspect, in the third aspect, the power distribution system state detecting means calculates a current value detected by the first and second current transformers when the switching means is turned on. A function for calculating the impedance ratio from a current value detected by the first current transformer for current and a current value stored in the storage means when the switching means is released; It comprised and was comprised.

  According to a fifth aspect, in the first to fourth aspects, the distribution system state detecting means is configured such that when the ratio of the impedance of the primary distribution system to the impedance of the secondary distribution system is less than 1, the automatic It is determined that the reverse power flow has occurred due to the connection of the distributed power supply to the secondary side of the voltage regulator, and the ratio of the impedance of the primary side distribution system to the impedance of the secondary side distribution system is greater than 1. In this case, it was configured to have a function of determining that the reverse power flow occurred due to the fact that a power substation was connected to the secondary side of the automatic voltage regulator by switching the system.

  According to a sixth aspect, in the fifth aspect, comprising an instrument transformer for detecting the secondary voltage of the automatic voltage regulator, and a voltage regulation relay for holding the secondary voltage at a set value, When the determination of the cause of reverse power flow by the distribution system state detection means is due to the fact that the distributed power source is linked to the secondary side of the automatic voltage regulator, the on-load tap changer switches the tap of the voltage regulation transformer. The secondary voltage is automatically adjusted by prohibiting fixing to a tap set in advance, and the determination of the cause of the reverse power flow by the distribution system state detection means is the secondary voltage of the automatic voltage regulator. When the power transformer substation is connected to the side, the on-load tap changer is configured to control the tap of the voltage regulating transformer to be fixed to the tap set in advance.

  According to the invention described in claim 1, when it is detected that a reverse power flow has occurred at the installation point of the automatic voltage regulator by the reverse current relay, a load is connected to the distribution line on the secondary side of the automatic voltage regulator, By detecting the current flowing through the load and the secondary current of the automatic voltage regulator, and then detecting the secondary current when the load is disconnected, the primary power distribution is obtained from these current values. Since it is possible to calculate the ratio between the impedance of the system and the impedance of the secondary distribution system, the existing automatic voltage regulator is equipped with a current transformer for detecting the current and a distribution system state detecting means for calculating the impedance ratio. In addition, the cause of the reverse power flow at the installation point of the automatic voltage regulator can be easily and reliably clarified from the impedance ratio, which is effective.

  According to the second aspect of the present invention, the step-down transformer excited by the voltage adjustment transformer of the automatic voltage regulator is detected when the reverse current is detected by the reverse relay at the installation point of the automatic voltage regulator. A load is connected to the distribution line, the current flowing through the load and the secondary current of the automatic voltage regulator are detected, and then the secondary current when the load is disconnected is detected. Thus, since the ratio of the impedance of the primary distribution system and the impedance of the secondary distribution system can be calculated from these current values, the load can be integrated into the automatic voltage regulator, While reducing the size of the automatic voltage regulator, the cause of the reverse power flow at the installation point of the automatic voltage regulator can be easily and reliably clarified from the calculated impedance ratio.

  According to the third aspect of the present invention, when a reverse power flow occurs at the installation point of the automatic voltage regulator, the switching means is once turned on by the output signal, and the load for impedance measurement is connected to the distribution line. Since the configuration is such that the switching means is again released after the control is executed, connection and disconnection of the impedance measurement load can be switched with a very simple configuration, which is convenient.

  According to the fourth aspect of the present invention, since the storage means for storing necessary data is provided, the secondary current when the load for impedance measurement is connected and the current flowing through the load are temporarily stored. Based on the secondary current when the load is disconnected and the secondary current and load current stored in the storage means, the impedance of the primary distribution system and the secondary distribution are stored. It becomes possible to calculate the impedance ratio of the system.

  According to the invention of claim 5, it is determined whether the substation and the load are connected to the primary side or the secondary side of the automatic voltage regulator depending on whether the calculated impedance ratio is larger or smaller than 1. It is possible to reliably determine whether the cause of the reverse power flow is due to system switching or due to linkage with the distributed power source.

  According to the sixth aspect of the present invention, when the cause of the reverse power flow is due to the fact that the distributed power source is linked to the secondary side of the automatic voltage regulator, the tap of the voltage regulating relay is settled by the on-load tap changer. Prohibiting fixing to the tap and continuing the control to bring the secondary voltage close to the set value without stopping, and the cause of the reverse power flow is that the substation is secondary to the distribution system switching The voltage on the load side can always be controlled by controlling the tap of the voltage regulating transformer to be fixed to the settling tap by the load tap changer. Is effective.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a circuit diagram showing an automatic voltage regulator (hereinafter referred to as SVR) 1 according to the present invention. In FIG. 1, reference numeral 2 denotes a tapped voltage regulating transformer.

  Reference numerals 3 and 4 denote distribution lines connected to the primary side and the secondary side of the voltage adjustment transformer 2, respectively, and 5 denotes a load tap changer for switching the tap of the voltage adjustment transformer 2. 6 is an instrument transformer for detecting the secondary side voltage of the SVR 1, and 7 is a first for detecting a current (hereinafter referred to as a secondary side current) flowing through the distribution line 4 connected to the secondary side of the SVR 1. It is a current transformer for instruments.

  8 is a voltage adjusting relay (90 relay) that gives a switching command to the on-load tap changer 5 so as to keep the secondary voltage of the SVR 1 detected by the instrument transformer 6 at a set value, and 9 is for the instrument. The reverse flow relay (67 relay) which detects the direction of the electric power flow in the installation point of SVR1 by using the output of the transformer 6 and the output of the 1st instrumental current transformer 7 as input is shown.

  That is, the SVR 1 shown in FIG. 1 includes the voltage regulating transformer 2, the on-load tap changer 5, the instrument transformer 6, the first instrument current transformer 7, the voltage regulation relay 8, and the reverse current relay 9. The secondary side voltage is controlled during forward flow, and fixedly controlled to a tap set in advance during reverse flow.

  Reference numeral 10 denotes a distribution system state detection device attached to the SVR 1, and the distribution system state detection device 10 is a transformer that steps down a load 11 and a switching means described later to a usable voltage (hereinafter referred to as a step-down transformer). 12, based on the current flowing through the load 11 when the load 11 is connected to the distribution line 4 via the step-down transformer 12 (hereinafter referred to as load current) and the secondary current before and after the connection of the load 11. Then, the distribution system state detection means 13 for calculating the ratio of the impedance of the primary side distribution system and the impedance of the secondary side distribution system, and the load 11 and the distribution line 4 according to the output of the distribution system state detection means 13 A switching means 14 for switching between connection and disconnection, a second instrument current transformer 15 provided between the distribution line 4 and the step-down transformer 12 for detecting the current flowing through the load 11, and The secondary current is detected and is configured to include a third current transformer 16 to be input to the power distribution system condition detecting means 13.

  Next, the operation of the automatic voltage regulator (SVR) 1 including the distribution system state detection device 10 will be described. First, the case where the SVR 1 operates alone will be described. The reverse relay 9 of the SVR 1 shown in FIG. 1 determines whether the power flow is forward or reverse at the installation point of the SVR 1 by monitoring the current phase with reference to the voltage phase on the secondary side of the SVR 1. .

  The voltage adjustment relay 8 detects the secondary side voltage of the SVR 1 from the output voltage of the instrument transformer 6 and brings the secondary side voltage close to a set value when the power flow is forward based on the output result of the reverse flow relay 9. As described above, a tap switching command is given to the on-load tap changer 5.

  The on-load tap changer 5 switches the tap of the voltage adjustment transformer 2 based on the tap change command of the voltage adjustment relay 8, and sets the voltage so that the secondary side voltage of the SVR 1 approaches the set value of the voltage adjustment relay 8. adjust.

  That is, if the secondary voltage of the SVR 1 is lower than the set value when the power flow is forward, the voltage adjustment relay 8 gives a boost command to the on-load tap changer 5, and as a result, the on-load tap changer 5 switches the tap of the voltage adjustment transformer 2 to the step-up side and adjusts the voltage so that the secondary side voltage approaches the settling value.

  When the secondary voltage of SVR1 is higher than the set value, the voltage adjustment relay 8 gives a step-down command to the on-load tap changer 5, and the voltage adjustment transformer 2 switches the tap to the step-down side. Adjust the voltage so that the secondary voltage approaches the set value.

  On the other hand, the power substation on the distribution line 3 side is disconnected by switching the distribution system in which the SVR 1 is installed, and the power substation existing on the distribution line 4 side causes 1 of the SVR 1 from the secondary distribution line 4 side of the SVR 1. When the power flow is reversely sent to the distribution line 3 on the next side, the reverse flow relay 9 inputs the output of the instrument transformer 6 and the output of the first instrument current transformer 7 and at the installation point of the SVR 1. Detect the direction of power flow.

  When a reverse power flow is detected by the reverse flow relay 9, the reverse flow relay 9 gives a tap switching command to the on-load tap changer 5 and fixes the tap of the voltage adjusting transformer 2 to the tap set in advance. To do.

  That is, the SVR 1 shown in FIG. 1 alone detects the direction of the power flow by the reverse flow relay 9 and controls the secondary voltage of the SVR 1 when the forward state is detected, and the reverse state is detected. When it is done, the tap of the voltage adjustment transformer 2 is fixed to a previously set tap (setting tap), and control is performed to prevent the primary side voltage from becoming abnormal.

  However, in the case where the reverse flow of the power flow is not caused by system switching but is caused by linkage of distributed power sources, when the control for fixing the SVR 1 to the tap set in advance as described above is executed, the above [Background Art ], It is possible to prevent the occurrence of an abnormality in the voltage of the distribution system, as in the prior art described in the section], but the voltage adjustment operation of the load connected to the secondary side is stopped.

  Thus, by providing the SVR 1 with the power distribution system state detection device 10 shown in FIG. 1, it is determined whether the cause of the reverse power flow is due to the switching of the system or the distributed power source. When the cause is due to the switching of the system, the tap is fixedly controlled. When the cause is due to the distributed power source, the secondary side voltage control is performed.

  That is, based on the output of the instrument transformer 6 constituting the SVR 1 shown in FIG. 1 and the output of the first instrument current transformer 7, the reverse flow relay 9 detects the power flow direction at the installation point of the SVR 1 (FIG. 2). As a result of step S1), the distribution system state detecting means 13 grasps that the reverse power flow is generated from the output signal of the reverse relay 9, and the switching means in step S2 of FIG. 14 is turned on (input), and the load 11 is connected to the distribution line 4 via the step-down transformer 12.

  Thereby, the current I2 flowing through the load 11 is detected by the second instrument current transformer 15, and the secondary current I1 ′ when the load 11 is connected is changed from the first instrument current transformer 7 to the third current transformer I3 ′. It is detected via the current transformer 16 (step S3 in FIG. 2) and stored in a storage means (not shown) provided in the distribution system state detection means 13 (step S4 in FIG. 2).

  When the current values I2 and I1 ′ are stored in the storage unit, the distribution system state detection unit 13 turns off (releases input) the switching unit 14 in step S5 shown in FIG. Is disconnected from the distribution line 4.

  Thereby, since the value of the secondary side current changes, the distribution system state detection means 13 detects again the secondary side current I1 after the value is changed by the third instrument current transformer 16. By taking in (step S6 in FIG. 2), together with the current values I2 and I1 ′ previously stored in the storage means (not shown), the primary power distribution with respect to the impedance Z2 of the secondary power distribution system of SVR1 The ratio of the system impedance Z1 is calculated by the following equation (step S7 in FIG. 2).

  Then, in step S8 of FIG. 2, it is determined whether the impedance ratio (Z1 / Z2) calculated by [Equation 1] is larger or smaller than 1, and as a result, the impedance ratio (Z1 / Z2) is smaller than 1. In step S9, the reverse relay 9 shown in FIG. 1 receives the output signal of the distribution system state detecting means 13, gives a tap switching command to the on-load tap switch 5, and the voltage adjusting transformer. It is prohibited to fix the tap of 2 to a previously set tap (settling tap).

  That is, when the impedance ratio (Z1 / Z2) is smaller than 1, the cause of the reverse power flow at the installation point of SVR1 is due to the linkage with the distributed power source, and the power supply substation exists on the primary side of SVR1. Accordingly, the voltage is automatically adjusted so that the secondary voltage of SVR1 approaches the set value.

  On the other hand, when the impedance ratio (Z1 / Z2) calculated by [Equation 1] is greater than 1 in step S8, the process proceeds to step S10, where the reverse flow relay 9 shown in FIG. The tap of voltage adjustment transformer 2 is fixed to the tap set in advance (setting tap) by giving a tap switching command to on-load tap changer 5 in response to the output signal of Control to prevent the voltage from becoming abnormal.

  That is, when the impedance ratio (Z1 / Z2) is greater than 1, a reverse power flow occurs at the installation point of SVR1 because the power substation is connected to the secondary side of SVR1 by switching the distribution system. Judgment and control to fix to the settling tap are performed.

  The reason why the power substation is connected to the primary side or the secondary side of the SVR 1 by comparing the impedance ratio (Z1 / Z2) with the numerical value 1 is as follows.

  That is, since the system capacity of a power substation is generally very large, it can be regarded as an infinite bus. Therefore, when the impedance ratio (Z1 / Z2) is smaller than 1, it can be determined that the primary side of SVR1 is connected to an infinite bus (power substation), and the impedance ratio (Z1 / Z2) Is greater than 1, it can be determined that the secondary side of SVR1 is connected to an infinite bus (power substation).

  If no reverse power flow is detected in step S1, the process proceeds to step S11 to automatically control the secondary side voltage.

  FIG. 3 shows a circuit configuration diagram of an automatic voltage regulator (SVR) 1A according to another embodiment of the present invention. The SVR 1A shown in FIG. 3 includes a step-down transformer 12 that is excited by the voltage adjusting transformer 2, and the step-down transformer 12 is turned on / off by the switching means 14 that operates according to a command from the distribution system state detection means 13. The load 11 is connected / disconnected to the distribution line 4 via the step-down transformer 12 according to the off state.

  The second instrument current transformer 15 is attached between the step-down transformer 12 and the load 11, and the distribution system state detection means 13 is connected to the load by the second instrument current transformer 15. 11 is detected and captured. The operation of the SVR 1A will be described below.

  The SVR 1A shown in FIG. 3 detects the power flow direction at the installation point of the SVR 1A by the reverse flow relay 9 based on the output of the instrument transformer 6 and the output of the first instrument current transformer 7 (step S1 in FIG. 2). As a result, if a reverse power flow occurs, the distribution system state detection means 13 grasps that the reverse power flow is generated from the output signal of the reverse flow relay 9, and turns on the switching means 14 in step S2 of FIG. The load 11 is connected to the distribution line 4 via the step-down transformer 12.

  Thereby, the current I2 flowing through the load 11 is detected by the second instrument current transformer 15, and the secondary current I1 'when the load 11 is connected is detected by the first instrument current transformer 7 ( Step S3 in FIG. 2 is stored in the storage means (not shown) of the distribution system state detection means 13 (step S4 in FIG. 2).

  When the current values I2 and I1 ′ are stored in the distribution system state detection unit 13, the distribution system state detection unit 13 turns off (releases the input) the switching unit 14 in step S5 shown in FIG. Then, the load 11 is disconnected from the distribution line 4.

  Thereby, since the value of the secondary side current changes, the distribution system state detection means 13 again detects the secondary side current I1 after the value is changed by the first instrument current transformer 7. By taking in (step S6 of FIG. 2), the ratio of the impedance Z1 of the primary distribution system to the impedance Z2 of the secondary distribution system of SVR1A together with the current values I2 and I1 ′ stored previously is (Step S7 in FIG. 2).

  Then, in step S8 in FIG. 2, it is determined whether the impedance ratio (Z1 / Z2) calculated by [Equation 2] is larger or smaller than 1, and as a result, the impedance ratio (Z1 / Z2) is smaller than 1. In this case, the process proceeds to step S9, where the reverse relay 9 shown in FIG. 3 receives the output signal from the distribution system state detecting means 13, gives a tap switching command to the on-load tap switch 5, and the voltage adjusting transformer. The second tap is prohibited from being fixed to a previously set tap (settling tap), and the voltage is automatically adjusted to bring the secondary voltage close to the set value.

  On the other hand, when the impedance ratio (Z1 / Z2) calculated by [Equation 2] is larger than 1 in step S8, the process proceeds to step S10, where the reverse flow relay 9 shown in FIG. By receiving the output signal of 13 and giving a tap switching command to the on-load tap changer 5, the tap of the voltage adjusting transformer 2 is fixed to a previously set tap (setting tap), and the voltage of the distribution line is Control to prevent abnormalities.

  If no reverse power flow is detected in step S1, the process proceeds to step S11 to automatically control the secondary side voltage.

  That is, the SVR 1A shown in FIG. 3 includes the step-down transformer 12 excited by the voltage adjusting transformer 2, and is configured to connect the load 11 via the switching means 14 to the step-down transformer 12. The integration of the SVR 1 and the distribution system state detection device 10 and the miniaturization of the device itself can be realized easily and reliably, which is very effective.

  Also in the SVR 1A shown in FIG. 3, it can be determined from the magnitude comparison between the impedance ratio (Z1 / Z2) and the numerical value 1 whether the power substation is connected to the primary side or the secondary side of the SVR 1A. The reason is the same as that shown in FIG.

  As described above, the automatic voltage regulator (SVR) 1, 1A according to the present invention is caused by the switching of the distribution system or when the reverse power flow occurs at the installation point of the SVR 1, 1A. If it is due to system switching, control is performed to fix the taps of SVR1 and 1A to the settling tap, and the cause of the reverse power flow is due to the distributed power supply In this case, since the secondary side voltage of SVR1, 1A is automatically adjusted to control the secondary side voltage close to the set value, the power substation is connected to the primary side as before. As a result of performing the tap fixing control in the state of being performed, it is possible to completely prevent the occurrence of a problem that the voltage adjustment operation of the load connected to the secondary side is stopped.

  Further, the step-down transformer 12 excited by the voltage adjusting transformer 2 and the load 11 connected to the step-down transformer 12 via the switching means 14 are provided, so that the SVR 1 and the distribution system state detection device 10 are integrated. In addition, it is possible to provide a small-sized SVR 1A, which is very effective.

  According to the present invention, when the occurrence of reverse power flow is detected by the reverse flow relay based on the output of the instrument transformer and the output of the first instrument current transformer, the switching means is switched according to the command of the distribution system state detection means. The load is connected to the distribution line via a step-down transformer. At this time, the current flowing through the load is detected by the second instrument current transformer, and stored in the storage means of the distribution system state detection means together with the secondary current of the SVR detected by the first instrument current transformer. Let Thereafter, the distribution system state detecting means detects and acquires the secondary current changed by releasing the switching-on state of the switching means with a first instrument current transformer, and previously stores the storage means. The ratio of the impedance of the primary side distribution system and the impedance of the secondary side distribution system can be calculated together with the current value stored in. From this impedance ratio, it is possible to reliably determine whether the reverse power flow at the installation point of the SVR is due to system switching or linkage with the distributed power source. In other words, the cause of the reverse power flow can be specified, so that the voltage control on the load side can always be performed according to the cause of the reverse power flow. Thus, it is possible to provide an automatic voltage regulator capable of appropriately controlling the load side voltage at all times.

It is a circuit block diagram of the automatic voltage regulator of this invention. It is a flowchart figure explaining operation | movement of the said automatic voltage regulator. It is a circuit block diagram of the automatic voltage regulator in the other Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A Automatic voltage regulator 2 Voltage regulation transformer 3, 4 Distribution line 5 Load tap changer 6 Instrument transformer 7 1st instrument current transformer 8 Voltage regulation relay 9 Backflow relay 10 Distribution system state detection apparatus DESCRIPTION OF SYMBOLS 11 Load 12 Step-down transformer 13 Distribution system state detection means 14 Switching means 15 2nd instrument current transformer 16 3rd instrument current transformer

Claims (6)

  In the automatic voltage regulator that automatically adjusts the load side voltage by the tap switching operation of the voltage adjustment transformer by the on-load tap changer installed in the middle of the distribution line, the power at the installation point of the automatic voltage regulator A reverse relay for detecting the direction of power flow, a load for impedance measurement connected to a distribution line on the secondary side of the automatic voltage regulator when the reverse power flow is detected by the reverse current relay, and the automatic voltage regulator A first current transformer for detecting a current flowing in the secondary side of the first current transformer, a second current transformer for detecting a current flowing in the load when the load is connected, and the second current transformer The impedance of the primary side distribution system and the secondary side distribution system calculated based on the change in the detection current by the current transformer and the change in the detection current by the first current transformer before and after the connection of the load Automatic voltage regulator, characterized in that the ratio of the impedance and configured by including determining distribution system condition detecting means cause the reverse flow.   In the automatic voltage regulator that automatically adjusts the load side voltage by the tap switching operation of the voltage adjustment transformer by the on-load tap changer installed in the middle of the distribution line, the power at the installation point of the automatic voltage regulator A reverse relay for detecting the direction of the power flow, and a load for impedance measurement connected to the distribution line via a step-down transformer excited by the voltage regulating transformer when the reverse power flow is detected by the reverse flow relay. A first instrument current transformer for detecting a current flowing in the secondary side of the automatic voltage regulator, and a second instrument current transformer for detecting a current flowing in the load when the load is connected And the input of the primary-side power distribution system calculated based on the change in the detected current by the second instrument current transformer and the detected current by the first instrument current transformer before and after the connection of the load. -Impedance and automatic voltage regulator, characterized in the ratio of the impedance on the secondary side distribution system that has been configured by including determining distribution system condition detecting means cause the reverse flow.   The distribution system state detection means includes switching means that is turned on / off according to the output signal, and operates the switching means according to the output signal of the reverse flow relay to thereby load the load on the distribution line. 3. The automatic voltage regulator according to claim 1, wherein the connection / disconnection is switched.   The distribution system state detection means includes storage means for storing current values detected by the first and second current transformers when the switching means is turned on, and the switching means is released. 4. The apparatus according to claim 3, further comprising a function of calculating the impedance ratio from a current value detected by the first instrument current transformer and a current value stored in the storage means. Automatic voltage regulator as described.   When the ratio of the impedance of the primary side distribution system to the impedance of the secondary side distribution system is smaller than 1, the distribution system state detection means is caused by the fact that the distributed power supply is linked to the secondary side of the automatic voltage regulator. If the ratio of the impedance of the primary distribution system to the impedance of the secondary distribution system is greater than 1, the secondary side of the automatic voltage regulator is switched by switching the system. 5. The automatic voltage regulator according to claim 1, further comprising a function of determining that the reverse power flow has occurred due to the connection of the power substation.   6. The automatic voltage regulator according to claim 5, further comprising an instrument transformer for detecting a secondary side voltage of the automatic voltage regulator, and a voltage regulation relay for holding the secondary side voltage at a set value. When the determination of the cause of the reverse power flow by the system state detection means is due to the fact that the distributed power source is linked to the secondary side of the automatic voltage regulator, the on-load tap changer pre-sets the tap of the voltage regulation transformer The secondary side voltage is automatically adjusted by prohibiting fixing to the tapped tap, and the determination of the cause of reverse power flow by the distribution system state detecting means is performed on the secondary side of the automatic voltage regulator. Automatic voltage regulation, characterized in that, when caused by the connection of a power substation, the on-load tap changer is configured to control the tap of the voltage regulation transformer to be fixed to a preset tap. vessel.

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