JP2023086205A - Voltage control method of distribution transformation facility, voltage control system, and distribution transformation facility - Google Patents

Abstract

To provide a voltage control method and the like for distribution transformation facility capable of detecting signs and occurrence of flicker and performing appropriate voltage control.SOLUTION: A voltage control method for a distribution transformation facility (1) that transforms extra-high voltage power of an extra-high voltage power system into high-voltage power of a high-voltage power system linked to a photovoltaic power generation facility by a transformer (21, 31, 41) includes the steps of: controlling a secondary voltage V2 of the transformer on the basis of a reference value determined according to an active power P on the secondary side of the transformer; determining occurrence or a sign of voltage flicker on the basis of a primary side voltage V1 or the secondary side voltage V2 of the transformer; and increasing the reference value when the occurrence or the sign of voltage flicker exists.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a voltage control method, a voltage control system, and a transformer facility, and more particularly to a voltage control method, a voltage control system, and a transformer facility for distribution.

Distribution substation equipment is installed between transmission lines in the power system, transforms the transmitted extra-high voltage power into high-voltage power for high-voltage consumers with a transformer, and transmits power to the distribution line of the high-voltage power system. Equipment. 2. Description of the Related Art In order to maintain the voltage of a high-voltage electric power system within a predetermined range, a voltage control device as disclosed in Patent Literature 1 is installed in power distribution transformer equipment. Voltage control is performed by step-up/step-down operation (LR control) by switching taps of a tap-changing transformer (LRT) on load, phase-modifying control by turning on/off power capacitors (SC) and shunt reactors (Shr), and the like.

JP-A-11-206018

By the way, in recent years, with the introduction of a purchase system for photovoltaic power generation, a large amount of photovoltaic power generation equipment has been installed, and has come to be linked to a power distribution system (high-voltage power system) via a power conditioner for photovoltaic power generation. A power conditioner for photovoltaic power generation injects reactive power into a distribution line according to the conditions of the associated distribution line. In addition, as a method of detecting power outages in the distribution system, reactive power is injected into the distribution line and confirmed. It has a function to prevent electrical accidents and ensure safety by disconnecting the distribution line from the photovoltaic power generation system when a power outage is detected. When a large amount of reactive power is injected into the distribution line due to sudden voltage fluctuations in the distribution line due to the cooperation of a large number of photovoltaic power generation systems, the system voltage repeatedly fluctuates, which is one of the factors that causes voltage flicker. .

As a voltage control device for electric power systems, there is a voltage/reactive power control (VQC) installed in a power transmission substation. VQC is capable of highly accurate voltage control, but does not have a function to deal with voltage flicker. Therefore, even if VQC, which has been conventionally used in power transmission substation equipment, is introduced as it is to distribution substation equipment, it is not possible to detect the sign or occurrence of voltage flicker, and voltage control according to voltage flicker is not possible. I had a problem. In addition, there is also the problem that if the amount of power generated by the photovoltaic power generation system exceeds the amount of demand in the distribution system and a reverse power flow occurs, proper voltage control cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and provides a voltage control method, a voltage control system, and a voltage control system capable of detecting signs and occurrences of voltage flicker and performing appropriate voltage control in power distribution substation equipment. It is an object to provide a distribution substation using this.

The above-mentioned problem is a voltage control method for distribution transformer equipment for transforming extra-high voltage power in an extra-high voltage power system into high-voltage power in a high-voltage power system linked to a photovoltaic power generation facility by means of a transformer. controlling the secondary voltage of the transformer based on a reference value determined according to the active power of the secondary; and controlling the voltage flicker based on the primary or secondary voltage of the transformer. It can be solved by a voltage control method including the step of determining the occurrence or sign, and the step of increasing the reference value when there is the occurrence or sign of voltage flicker.

When voltage flicker occurs, the voltage on the secondary side of the transformer fluctuates. Therefore, the occurrence of voltage flicker or its sign is determined, and if there is the occurrence of voltage flicker or its sign, the reference value serving as the reference for the secondary side voltage control is increased to perform appropriate voltage control. becomes possible.

In addition, the step of determining the occurrence or sign of voltage flicker is performed when the primary side voltage is equal to or lower than a predetermined voltage for a predetermined period of time, or when the flicker value of the primary side voltage or secondary side voltage is maintained for a predetermined period of time. It is desirable to include the step of determining that there is an occurrence or sign of voltage flicker when the value is equal to or greater than the value.

Voltage flicker can be detected by an increase in the flicker value of the primary side voltage or secondary side voltage of the transformer, and a sign of voltage flicker can be determined by a drop in the primary side voltage of the transformer. Since the voltage and the flicker value constantly fluctuate, it is possible to make a highly accurate determination by comparing the voltage and the flicker value with the threshold over a predetermined period.

Further, after it is determined that voltage flicker has occurred or is a sign, the primary side voltage is equal to or higher than a predetermined voltage for a predetermined period of time, and the flicker value of the primary side voltage or secondary side voltage is a predetermined value for a predetermined period of time. It is preferable to further include the step of returning the reference value to the value before the increase when the following is reached.

Elimination of voltage flicker can be determined by a decrease in the flicker value of the primary side voltage or secondary side voltage of the transformer, and elimination of the sign of voltage flicker can be determined by an increase in the primary side voltage of the transformer. When the problem is solved, the reference value, which is the reference for the secondary voltage control, is returned to the original value, so that proper voltage control can be performed in a normal state without voltage flicker. In addition, since the voltage and flicker value constantly fluctuate, it is possible to make a highly accurate determination by comparing the voltage and flicker value with the threshold over a predetermined period.

Moreover, it is desirable that the step of controlling the secondary voltage of the transformer is performed by at least one of phase modifying control and LR control, and that control considering reactive power is preferentially applied. Since the main cause of voltage flicker is excessive reactive power injection by the photovoltaic power generation equipment, proper voltage control becomes possible by prioritizing reactive power control by phase modification control.

Also, phase modifying control may be performed by connecting either a power capacitor or a shunt reactor to the high-voltage power system, and LR control may be performed by changing the transformation ratio of the transformer. desirable. Adjusting reactive power by selectively connecting power capacitors and shunt reactors with different phase control directions to a high-voltage power system, and adjusting both active power and reactive power by changing the transformation ratio of a transformer. can be done.

Moreover, it is desirable to further include the step of issuing an alarm when it is determined that there is an occurrence or sign of voltage flicker. Occurrence or signs of voltage flicker can cause power transmission problems, so it is possible to take necessary measures to prevent problems by issuing warnings to power system administrators and power system management systems. Become.

Furthermore, the above problems can also be solved by a distribution substation and its voltage control system that implements the voltage control method described above.

According to the voltage control method, voltage control system, and distribution substation equipment for distribution substation equipment according to the present invention, it is possible to detect signs and occurrences of flicker in distribution substation equipment and perform appropriate voltage control. Become.

1 is a schematic configuration diagram of a distribution substation according to an embodiment of the present invention; FIG. 1 is a schematic configuration diagram of a voltage control system according to an embodiment of the present invention; FIG. 4 is a flow chart of a voltage control method according to an embodiment of the invention; FIG. 4 is an explanatory diagram of a PV curve; 4 is a flow chart of a voltage control method according to an embodiment of the invention; 4 is a flow chart of a voltage control method according to an embodiment of the invention; FIG. 10 is an explanatory diagram of changing a reference value; FIG. 4 is an explanatory diagram of operation mode transition;

Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an example of the configuration of a power distribution substation according to an embodiment of the present invention. The power distribution transforming equipment 1 is a power transforming equipment for transforming extra high voltage power of 66 kV into high voltage power of 6 kV. The power distribution transformer facility 1 has three banks 20, 30, and 40, each of which is provided with on-load tap-changing transformers (LRT) 21, 31, and 41 for transforming extra high voltage power into high voltage power. there is A primary bus 51 of an extra high voltage power system is connected to the primary side of each transformer 21 , 31 , 41 . A transformer 52 is connected to the primary bus 51 to measure the voltage of the extra high voltage power system, that is, the primary side voltage _V1 of the transformers 21 , 31 and 41 . Secondary buses 53 , 54 , 55 of the high-voltage power system are connected to the secondary sides of the transformers 21 , 31 , 41 . Photovoltaic power generation facilities 61 , 62 , 63 are linked to the secondary buses 53 , 54 , 55 .

Furthermore, the distribution substation equipment 1 includes a distribution voltage control system (distribution VQC) 10, which is voltage control means for controlling the secondary voltages of the transformers 21, 31, and 41. Primary side voltage _V1 of devices 21, 31 and 41 is input. The power distribution VQC 10 uses phase modifying means 25, 26, 35, 36, 45, 46 and transformer By controlling at least one of the transformation ratios of 21, 31, 41, the secondary side voltage _V2 of the transformers 21, 31, 41 is controlled, and the primary side voltage V of the transformers 21, 31, 41 is controlled. It has a function of determining the occurrence or sign of voltage flicker based on _{the primary} or secondary side voltage _V2 , and increasing the above-described reference value when there is the occurrence or sign of voltage flicker.

Each bank 20, 30, 40 includes, in addition to primary transformers 21, 31, 41, secondary transformers 22, 32, 42, current measuring means 23, 33, 43, 90 relays 24, 34, 44; shunt reactors (Shr) 25, 35, 45; power capacitors (SC) 26, 36, 46; switches 27, 28, 37, 38, 47, 48; , 39, 49.

The transformers 22 , 32 , 42 are connected to the secondary buses 53 , 54 , 55 and measure the voltage of the high voltage power system, ie the secondary voltage V ₂ of the transformers 21 , 31 , 41 . The measured secondary voltage V ₂ is input to the distribution VQC 10 and 90 relays 24 , 34 , 44 . Current measuring means 23 , 33 , 43 measure secondary currents I ₂ of transformers 21 , 31 , 41 from the magnitude of magnetic fields generated around secondary buses 53 , 54 , 55 . The measured secondary current I ₂ is input to distribution VQC 10 and 90 relays 24 , 34 , 44 .

The 90 relays 24, 34, 44 switch the taps of the transformers 21, 31, 41 based on the input secondary voltage _V2 and secondary current _I2 of the transformers 21, 31, 41. , to control the secondary voltage _V2 by changing the transformation ratios of the transformers 21 , 31 , 41 . When the distribution VQC 10 controls the transformation ratio of the transformers 21, 31, 41, the control by the 90 relays 24, 34, 44 is disabled.

Shunt reactors (Shr) 25, 35, 45 are connected to secondary buses 53, 54, 55 via switches 27, 37, 47, and are inductive phase modifying means for controlling reactive power in the high voltage power system. is. The shunt reactors (Shr) 25, 35, 45 can be connected or disconnected to the high voltage power system by turning on or off switches 27, 37, 47.

Power capacitors (SC) 26, 36, 46 are connected to secondary buses 53, 54, 55 through switches 28, 38, 48 to provide capacitive phase modifying means for controlling reactive power in the high voltage power system. is. Power capacitors (SC) 26,36,46 can be connected or disconnected from the high voltage power system by closing or opening switches 28,38,48.

Since the shunt reactors (Shr) 25, 35, 45 and the power capacitors (SC) 26, 36, 46 are in opposite phase-modifying directions, the switches 27, 37, 47 and one of the switches 28, 38, 48 is turned on. In addition, the required number of phase modifying means (shunt reactor (Shr) and power capacitor (SC)) can be installed. , can control disconnection with the high-voltage power system.

The power capacitor controllers 29, 39, 49 switch the switches 28, 38, 48 to connect the power capacitors (SC) 26, 36, 46 to the high voltage power system during a set period of time. It is a device that adjusts the reactive power of the power system to control the secondary voltage _V2 . When the power distribution VQC 10 performs phase modifying control, the control by the power capacitor controllers 29, 39, 49 is disabled.

Next, the configuration of a distribution voltage control system (distribution VQC) 10, which is an example of an embodiment of the present invention, will be described with reference to FIG. The distribution VQC 10 comprises flicker meters 15 , 16 , a wireless router 17 and a system controller 11 . The flicker meter 15 is connected to the primary-side transformer 52, acquires the primary-side voltage _V1 of the transformers 21, 31, and 41, and calculates the flicker value f of the primary-side voltage _V1 . The flicker meter 16 is connected to the transformers 22, 32, 42 on the secondary side of each bank 20, 30, 40 to obtain the secondary voltage _V2 of the transformers 21, 31, 41 to A voltage flicker value f is calculated. Here, the "flicker value" is a scale representing the magnitude of voltage flicker. In the power distribution VQC 10 of the present embodiment, the IEC flicker meter considering the flicker visibility curve is used as the flicker value, but other scales may be used.

The wireless router 17 is a router that relays wireless communication between devices inside and outside the distribution VQC 10 . For example, the flicker value f obtained by the flicker meters 15 and 16 can be transmitted to the system control device 11 via the wireless router 17, or transmitted to the control PC 18 installed outside the power distribution VQC 10. . Also, an alarm issued by the system control device 11 can be transmitted to the control PC 18 .

The system control device 11 has a computer configuration including a processor 12 , a recording medium 13 connected to the processor 12 , and a timer 14 . System controller 11 receives flicker values f from flicker meters 15 and 16 . Further, the system control device 11 is connected to the transformers 22, 32, 42, 52 and the current measuring means 23, 33, 43, and the primary side voltage V ₁ and the secondary side voltage V of the transformers 21, 31, 41 ₂ and secondary current _I2 . Furthermore, the system controller 11 is connected to the transformers 21, 31, 41 and the switches 27, 28, 37, 38, 47, 48 of the phase modifying means 25, 26, 35, 36, 45, 46 to The taps of the transformers 21, 31, 41 are switched to change the transformation ratio of the transformers 21, 31, 41, and the phase modifying means (shunt reactors 25, 35, 45 and power capacitors 26, 36, 46) and high voltage power It can be disconnected from the system. In addition, the system control device 11 is connected to a remote monitoring control device 19 that remotely manages the distribution VQC 10 from a location remote from the distribution substation 1, and transmits information processed by the distribution VQC 10 and generated alarms. can be done.

The system control device 11 determines the occurrence or sign of voltage flicker based on the primary side voltage V ₁ of the transformers 21, 31, 41 or the flicker value f obtained by the flicker meters 15, 16, and determines the voltage flicker. Based on the reference value determined according to the active power P on the secondary side of the transformers 21, 31, 41, the secondary voltage _V2 of the transformers 21, 31, 41 is controlled, and the voltage flicker f It has the function of increasing the reference value when there is an occurrence or a sign. These functions are described in a program stored in the recording medium 13 and implemented by the processor 12 executing the program.

The recording medium 13 is a computer-readable recording medium composed of semiconductor memory such as RAM, SSD, flash memory, or magnetic memory such as HDD. Also, the timer 14 generates a clock signal of a predetermined cycle and provides it to the processor 12, and is used for operation management of the processor 12 and time measurement when flicker occurs or a sign is detected.

Next, the operation of the distribution voltage control system (distribution VQC) 10, that is, an example of an embodiment of the voltage control method according to the present invention will be described with reference to FIGS. FIG. 3 is a flow chart of the basic voltage control operation of the distribution VQC 10. FIG. FIG. 4 is an explanatory diagram of a PV curve used in basic voltage control operation. 5a and 5b determine the occurrence of voltage flicker or its sign, switch the operation mode (normal mode or flicker mode), and change the reference value used in the basic voltage control operation according to the operation mode. 3 is a flow chart of a voltage control operation for optimizing voltage control. FIG. 6 is an explanatory diagram of changing the reference value. FIG. 7 is an explanatory diagram of operation mode transition by flicker detection/prediction determination.

First, based on FIG. 3, the basic voltage control operation of the distribution VQC 10 will be described. The basic voltage control operation is performed periodically or repeatedly at timing according to predetermined settings. First, the processor 12 obtains the secondary side voltage V2 of the transformers 21, 31, 41 from the transformers 22, 32, 42 and the secondary side voltage _V2 of the transformers 21, 31, 41 from the current measuring means 23, 33, 43. A current _I2 is obtained respectively (step 101). Next, processor 12 obtains active power P and reactive power Q on the secondary side of transformers 21, 31 and 41 from secondary side voltage _V2 and secondary side current _I2 (step 102). When the power supplied from the photovoltaic power generation facilities 61, 62, and 63 exceeds the total power demand of the high-voltage power system and a reverse power flow occurs from the high-voltage power system to the special high-voltage power system, the active power P is a negative value. becomes. Next, the processor 12 refers to the PV curve stored in the recording medium 13, acquires the upper limit value and the lower limit value of the secondary voltage _V2 corresponding to the found active power P, and converts the transformer 22, 32 and 42 are compared with the secondary side voltage _V2 (step 103).

FIG. 4 shows an example of a PV curve. The PV curve is composed of five curves 71 to 75 with the active power P on the horizontal axis and the secondary voltage _V2 on the vertical axis. In FIG. 4, the PV curve is shown in the form of a graph for convenience of explanation, but the recording medium 13 shows the relationship between the active power P and the secondary voltage _V2 in the form of a function or a table. stored. A curve 73 is the optimum value of the secondary voltage _V2 corresponding to the active power P, which is the reference value for voltage control. A curve 73 is created by interpolating a plurality of target points S ₁ , S ₂ , S ₃ , S ₄ , S ₅ . In FIG. 4, linear interpolation is performed between target points S ₁ , S ₂ , S ₃ , S ₄ and S ₅ .

Curves 72 and 74 are the upper and lower deadband limits where the difference between the reference and measured values is judged to be insignificant. A dead zone is provided to prevent constant operation. Curves 72 and 74 are set based on the reference value of curve 73 (eg, ±1% of the reference value). When the distribution substation 1 is operating normally, the secondary voltage _V2 is within the range between the upper limit and the lower limit. Curves 71 and 75 are upper and lower alarm values of secondary voltage _V2 corresponding to active power P. FIG.

If the measured value of the secondary voltage _V2 with respect to the active power P is located at _M2 in FIG. 4, the measured value _M2 is within the alarm output range of the PV curve (secondary side voltage _V2 exceeds the PV curve 71 of the upper limit). Then, the processor 12 issues an alarm to the control PC 18 and the remote monitoring control device 19 to notify that an abnormality has occurred (step 105).

If the measured value of the secondary voltage _V2 is outside the alarm output range of the PV curve, the processor 12 determines whether reverse power flow from the high voltage power system to the special high voltage power system is occurring. Determine (step 104). Specifically, it is determined whether or not the sign of the active power P is a negative value. For example, when the measured value of the secondary voltage _V2 with respect to the active power P is located at _M1 in FIG. 4, the measured value _M1 is outside the alarm output range of the PV curve, but the active power P is a negative value, it is determined that reverse power flow is occurring. Then, the processor 12 issues an alarm to the control PC 18 and the remote monitoring control device 19 to notify that the reverse power flow has occurred (step 105).

After that, the processor 12 determines whether the measured value of the secondary voltage _V2 with respect to the active power P is within the dead band. End (step 106). On the other hand, if it is not within the dead band, the processor 12 determines the error ΔV between the measured value of the secondary voltage _V2 and the reference value. For example, if the measured value _of the secondary voltage _V2 with respect to the active power P is located at _M3 in FIG. end the action. On the other hand, when the measured values of the secondary voltage _V2 with respect to the active power P are located at _M1 and _M4 in FIG. 4, the error ΔV between the measured values _M1 and _M4 and the reference value is obtained. The obtained error ΔV is integrated with the error ΔV obtained in the previous basic voltage control operation (step 107).

Next, the processor 12 determines whether or not the integrated value is within a predetermined range, and if it is within the predetermined range, the voltage control is not required and the process ends (step 108). On the other hand, when it exceeds the predetermined range, the secondary side voltage _V2 of the transformers 21, 31, and 41 is controlled. At this time, control that considers reactive power is preferentially applied. For example, voltage control includes phase modifying control that adjusts reactive power and LR control that changes the transformation ratio of transformers 21, 31, and 41. The main cause of voltage flicker is the Because of excessive reactive power injection, reactive power control by phase modifying control is applied with priority over LR control. More specifically, the processor 12 first generates shunt reactors (Shr) 25, 35 according to the sign of the calculated reactive power Q (or the phase of the secondary voltage _V2 and the secondary current _I2 ). , 45 and power capacitors (SC) 26, 36, 46, the appropriate phase modifying means is selected. When there are a plurality of shunt reactors and power capacitors, an arbitrary number of phase modifying means are selected from among them according to the control amount. Next, the processor 12 estimates the secondary voltage _V2 when the selected phase modifying means is connected to the high-voltage power system, and determines whether or not the selected phase modifying means alone is controllable ( step 109).

If control is possible only with the selected phase modifying means, the processor 12 closes or opens the switches 27, 28, 37, 38, 47, and 48 corresponding to the selected phase modifying means to activate the selected phase modifying means. A phase means is connected or disconnected from the high voltage power system (step 110). On the other hand, if it is expected that sufficient control cannot be performed with only the selected phase modifying means, the processor 12 turns on the switches 27, 28, 37, 38, 47, and 48 corresponding to the phase modifying means. In addition to opening, LR control is performed to change the transformation ratio by switching the taps of the transformers 21, 31, and 41 (step 111). Processor 12 then resets the integrated value and ends the basic voltage control operation (step 112).

The basic voltage control operation described above is performed independently for each of the banks 20, 30, and 40. FIG. That is, based on the reference value determined according to the active power P on the secondary side of the transformer 21 obtained from the measured values of the secondary voltage _V2 and the secondary current _I2 of the transformer 21 of the bank 20 , controls the secondary voltage of transformer 21 of bank 20 . Also, based on a reference value determined according to the active power P on the secondary side of the transformer 31 obtained from the measured values of the secondary voltage _V2 and the secondary current _I2 of the transformer 31 of the bank 30 , controls the secondary voltage of transformer 31 of bank 30 . Similarly, based on a reference value determined according to the active power P on the secondary side of the transformer 41 obtained from the measured values of the secondary voltage _V2 and the secondary current _I2 of the transformer 41 of the bank 40 to control the secondary voltage of transformer 41 of bank 40 .

Next, the voltage control operation for determining the occurrence of voltage flicker or its sign and changing the PV curve (reference value) according to the operation mode will be described with reference to FIGS. 5a and 5b. 5a and 5b are performed periodically or repeatedly at timing according to predetermined settings, synchronously or independently of the basic voltage control operation shown in FIG. FIG. 5a is a flow chart when the operation mode is a normal mode without voltage flicker, and FIG. 5b is a flow chart when the operation mode is a flicker mode with flicker occurrence or indication.

When operating in the normal mode, first, the flicker meter 15 outputs the voltage _V1 on the primary side of the transformers 21, 31, and 41 from the transformer 52, and the flicker meter 16 outputs the transformer voltage V1 from the transformers 22, 32, and 42. The secondary voltages _V2 of the devices 21, 31 and 41 are obtained (step 201). Next, the flicker meters 15 and 16 obtain respective flicker values f (IEC flicker meter values) from the obtained primary side voltage _V1 and secondary side voltage _V2 (step 202).

Next, the processor 12 receives the flicker value f from the flicker meters 15 and 16 via the wireless router 17, and determines whether the state where the flicker value f is equal to or higher than the flicker threshold value _fth continues for a predetermined time _tth ( step 203). For example, although the flowchart of FIG. 5a is repeatedly executed as described above, the first execution time at which it is determined that the flicker value f is greater than or equal to the flicker threshold value _fth is obtained from the timer 14 and stored in the recording medium 13. When it is determined that the flicker value f is equal to or greater than the flicker threshold value _fth during subsequent execution, it is determined whether or not the difference from the time of execution is equal to or greater than a predetermined time _tth . . When the flicker value f becomes less than the flicker threshold value _fth , the memory in the recording medium 13 is erased and reset. The flicker threshold _fth and the predetermined time _tth may be set to different values for the primary side voltage _V1 and the secondary side voltage _V2 and for each of the banks 20, 30, and 40, or may be set to the same value. There may be.

If it is determined that the flicker value f is greater than or equal to the flicker threshold value f _th for the predetermined time t _th , that is, if voltage flicker occurs, the processor 12 sets the reference value of the PV curve to Increase (step 206). For example, as shown in FIG. 6, each of the plurality of target points S ₁ , S ₂ , S ₃ , S ₄ , and S ₅ serving as the reference of the curve 73 is increased by a predetermined amount or a predetermined magnification to create a new target point S ₁ ', S ₂ ', S ₃ ', S ₄ ', S ₅ ' are set, and new target points S ₁ ', S ₂ ', S ₃ ', S ₄ ', S ₅ ' are interpolated to obtain the reference Generate a new curve 73' of values. The other four curves 71, 72, 74, 75 are also generated based on the new curve 73'. Also, the processor 12 issues an alarm to the control PC 18 and the remote monitoring control device 19 to notify that voltage flicker has occurred (step 207), and changes the operation mode to the flicker mode (step 208). After the transition, instead of the normal mode flow of FIG. 5a, the flicker mode flow shown in FIG. 5b is repeatedly executed until the normal mode is transitioned again.

On the other hand, if it is determined in step 203 that the state in which the flicker value f is equal to or greater than the flicker threshold value f _th has not continued for the predetermined time t _th , that is, if no voltage flicker has occurred, the processor 12 outputs 1 It is determined whether the state in which the secondary voltage _V1 is equal to or lower than the voltage threshold _Vth continues for a predetermined time _tth (step 204). For example, the time at which it was first determined that the primary-side voltage _V1 became equal to or lower than the voltage threshold _Vth was obtained from the timer 14 and stored in the recording medium 13. When it is determined that the primary-side voltage _V1 is equal to or less than the voltage threshold _Vth , it is determined whether or not the difference from the time of execution is equal to or greater than a predetermined time _tth . When the primary side voltage _V1 exceeds the voltage threshold _Vth , the memory in the recording medium 13 is erased and reset. The predetermined time _tth may be set to a different value from the voltage flicker detection (step 203), or may be the same value.

If it is determined that the state in which the primary side voltage _V1 is equal to or lower than the voltage threshold _Vth continues for a predetermined time _tth , that is, if there is a sign of voltage flicker, the processor 12 outputs the PV curve The reference value is increased (step 206), an alarm is issued to the control PC 18 and the remote monitoring control device 19 to notify that there is a sign of voltage flicker (step 207), and the operation mode is changed to the flicker mode. (Step 208).

On the other hand, if it is determined in step 204 that the state in which the primary side voltage _V1 is equal to or lower than the voltage threshold _Vth has not continued for the predetermined time _tth , the operation mode is maintained in the normal mode (step 205). .

The above is the voltage control operation related to voltage flicker generation/prediction determination and reference value change when the operation mode is the normal mode.

Next, with reference to FIG. 5b, the voltage control operation regarding voltage flicker occurrence/prediction determination and reference value change when the operation mode is the flicker mode will be described. The operation in the flicker mode is almost the reverse of the operation in the normal mode.

That is, first, the flicker meter 15 detects the primary side voltage _V1 of the transformers 21, 31, and 41 from the transformer 52, and the flicker meter 16 detects the primary voltage V1 of the transformers 21, 31, and 41 from the transformers 22, 32, and 42. Each secondary voltage _V2 is obtained (step 211). Next, the flicker meters 15 and 16 obtain respective flicker values f (IEC flicker meter values) from the obtained primary side voltage _V1 and secondary side voltage _V2 (step 212).

Next, the processor 12 receives the flicker value f from the flicker meters 15 and 16 via the wireless router 17, and determines whether the state where the flicker value f is equal to or less than the flicker threshold value _fth continues for a predetermined time _tth ( step 213). The flicker threshold _fth and the predetermined time _tth may be set to different values for the primary side voltage _V1 and the secondary side voltage _V2 and for each of the banks 20, 30, and 40, or may be set to the same value. It may be the same value as or different from the flicker determination in normal mode (step 203 in FIG. 5a).

If it is determined that the flicker value f is equal to or lower than the flicker threshold value _fth for the predetermined time _tth , that is, if the voltage flicker is eliminated, the processor 12 changes the primary side voltage _V1 to the voltage It is determined whether or not the state of being equal to or greater than the threshold value V _th continues for a predetermined time t _th (step 214). The predetermined time t _th may be set to a value different from that in the step of determining the elimination of voltage flicker (step 213), or may be the same value.

If it is determined that the state in which the primary-side voltage _V1 is equal to or lower than the voltage threshold _Vth has continued for a predetermined time _tth , that is, if it is determined that the sign of voltage flicker has disappeared, the processor 12 performs P - Return the reference value of the V-curve to the value before it was increased (step 216). For example, in FIG. 6, the new target points S ₁ ', S ₂ ', S ₃ ', S ₄ ', S ₅ ' set in step 206 are replaced with the original target points S ₁ , S ₂ , S ₃ . , S ₄ , and S ₅ to interpolate back to the curve 73 of the reference value before the increase. The other four curves 71, 72, 74 and 75 are also returned to the curves before the increase. In order to notify that the voltage flicker has been resolved, the processor 12 also stops issuing alarms to the control PC 18 and the remote monitoring control device 19 (step 217), and shifts the operation mode to the normal mode ( step 218). After the transition, the normal mode flow shown in FIG. 5a is repeatedly executed until the transition to the flicker mode is made again.

On the other hand, if it is determined in step 213 that the state in which the flicker value f is equal to or less than the flicker threshold value _fth has not continued for the predetermined time _tth , or if it is determined in step 214 that the primary side voltage _V1 is lower than the voltage threshold value _Vth If it is determined that the above state has not continued for the predetermined time _tth , the operation mode is maintained in the flicker mode (step 215).

The above is the voltage control operation related to voltage flicker occurrence/prediction determination and reference value change when the operation mode is the flicker mode.

FIG. 7 shows an example of operation mode transition. In the figure, the horizontal axis represents time and the vertical axis represents the primary voltage _V1 and the flicker value f, showing temporal changes in the primary voltage _V1 and the flicker value f. . At time _t0 during operation in the normal mode, the flicker value f becomes equal to _or greater than the flicker threshold fth, but becomes equal to or less than the flicker threshold _fth at time _t1 before the predetermined time _tth elapses, so the normal mode is maintained. Thereafter, at time _t2 , the primary side voltage _V1 becomes equal to or less than the voltage threshold _Vth , and remains equal to or less than the voltage threshold _Vth until time _t3 when a predetermined time _tth elapses from time _t2 . At time _t3 , the predetermined time tth has not passed since the flicker value f became equal to _or greater than the flicker threshold fth, but the predetermined time _tth has not passed since the primary side voltage _V1 became equal to or less than the voltage threshold _{Vth .} Since the time has elapsed, the normal mode is changed to the flicker mode at time _t3 , and the reference value (PV curve) is increased.

Thereafter, at time _t4 , the primary side voltage _V1 becomes equal to or higher than the voltage threshold _Vth , and remains equal to or higher than the voltage threshold _Vth until time _t6 after a predetermined time _tth has elapsed. On the other hand, the flicker value f becomes less than or equal to the flicker threshold _fth at time _t5 , and is still less than or equal to the flicker threshold _fth at time _t6 , but the predetermined time _tth has not passed since it became less than or equal to the flicker threshold _fth . Therefore, at time _t6 , the flicker mode is maintained. After that, the primary side voltage _V1 continues to be equal to or higher than the voltage threshold value _Vth , and the flicker value f is maintained to be equal to _{or lower} than the flicker threshold value _fth . After that, a predetermined time t _th elapses. Then, at time _t7 , the flicker mode is changed to the normal mode, and the reference value (PV curve) is returned to the value before being increased.

The invention made by the inventors of the present application has been specifically described above based on the embodiments, but the invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. . For example, the communication between the flicker meters 15 and 16, the system control device 11, the control PC 18, and the remote monitoring control device 19 may be wireless communication, wired communication, or communication via an information network such as the Internet. . In addition, distribution VQC 10 and other components (transformers 22, 32, 42, 52, current measuring means 23, 33, 43, remote monitoring and control device 19, transformers 21, 31, 41, phase modifying means 25, 26, 35, 36, 45, 46) may be wireless communication, wired communication, or communication via an information network such as the Internet.

Furthermore, in the above-described embodiment, the functions of the power distribution VQC 10 are realized by the flicker meters 15 and 16 and the system controller 11, but each function may be configured by individual hardware or software, or a combination thereof. may For example, the flicker value may be obtained by the processor 12 of the system controller 11 instead of using the flicker meters 15 and 16 to implement the voltage control method according to the present invention.

1 Distribution substation equipment 10 Distribution voltage control system (distribution VQC)
11 System control device 12 Processor 13 Recording medium 14 Timers 15, 16 Flicker meter 17 Wireless router 18 Control PC
19 remote monitoring control device 20 1B
21, 31, 41 transformers 22, 32, 42, 52 transformers 23, 33, 43 current measuring means 24, 34, 44 90 relays 25, 35, 45 shunt reactors (phase modifying means)
26, 36, 46 power capacitor (phase modifying means)
27, 28, 37, 38, 47, 48 switches 29, 39, 49 power capacitor controller 30 2B
40 3B
51 Primary Bus (Extra High Voltage Power System)
53, 54, 55 Secondary bus (high voltage power system)
61, 62, 63 Solar power generation equipment 71 PV curve ( _V2 upper limit alarm value)
72 PV curve (dead zone upper limit)
73, 73' PV curve (reference value)
74 PV curve (lower limit of dead zone)
75 PV curve ( _V2 lower limit alarm value)

Claims (8)

A voltage control method for distribution transformer equipment for transforming extra-high voltage power in an extra-high voltage power system to high-voltage power in a high-voltage power system linked to photovoltaic power generation equipment by means of a transformer,
controlling the secondary side voltage of the transformer based on a reference value determined according to the active power of the secondary side of the transformer;
determining the occurrence or sign of voltage flicker based on the primary side voltage or secondary side voltage of the transformer;
increasing the reference value if there is an occurrence or sign of the voltage flicker;
voltage control method, including The step of determining the occurrence or sign of voltage flicker is performed when the primary side voltage is equal to or lower than a predetermined voltage for a predetermined period of time, or when the flicker value of the primary side voltage or the secondary side voltage for a predetermined period of time is determined. 2. The method according to claim 1, further comprising the step of determining that said voltage flicker has occurred or is a sign of said voltage flicker when is equal to or greater than a predetermined value. After determining that the voltage flicker has occurred or is a sign, the primary side voltage is equal to or higher than a predetermined voltage for a predetermined period, and the flicker value of the primary side voltage or the secondary side voltage is maintained for a predetermined period. 3. The method of claim 2, further comprising the step of returning the reference value to the value before increasing it if it falls below a predetermined value. The step of controlling the secondary voltage of the transformer is performed by at least one of phase modifying control and LR control, and control considering reactive power is preferentially applied. A method according to any one of paragraphs. The phase modifying control is performed by connecting one of a power capacitor and a shunt reactor to the high-voltage power system,
The LR control is performed by changing the transformation ratio of the transformer,
5. The method of claim 4. 6. The method according to any one of claims 1 to 5, further comprising issuing an alarm when it is determined that said voltage flicker occurs or is a precursor. A voltage control system for power distribution transformer equipment that transforms extra-high voltage power in an extra-high voltage power system to high-voltage power in a high-voltage power system linked to a photovoltaic power generation facility by means of a transformer,
a flicker meter for determining a flicker value of the primary side voltage or the secondary side voltage of the transformer;
A system controller,
a computer;
to the computer;
a function of determining the occurrence or sign of voltage flicker based on the primary side voltage of the transformer or the flicker value;
A function of controlling the secondary side voltage of the transformer based on a reference value determined according to the active power of the secondary side of the transformer;
a function of increasing the reference value when the voltage flicker occurs or is a sign;
a computer-readable recording medium recording a program for realizing
a system controller comprising
A distribution voltage control system comprising: A transformer with a changeable transformation ratio that converts the extra high voltage of the extra high voltage power system to the high voltage of the high voltage power system linked to the photovoltaic power generation equipment;
a transformer for measuring primary and secondary voltages of said transformer;
current measuring means for measuring the secondary current of the transformer;
phase modifying means capable of switching between disconnection and disconnection of the high-voltage power system;
At least one of the phase modifying means and the transformation ratio is controlled based on a reference value determined according to the active power on the secondary side of the transformer to control the secondary voltage of the transformer. voltage control means;
with
The voltage control means determines the occurrence or sign of voltage flicker based on the primary side voltage or the secondary side voltage, and increases the reference value when the voltage flicker occurs or is the sign. ,
Distribution substation equipment.

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