JP2001016783A - Reverse power flow preventing device for private power generating facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reverse power flow preventing device, which can inexpensively prevent the occurrence of a reverse power flow to a power supplying side due to load fluctuations with a simple constitution, and can serve for a long period. SOLUTION: A reverse power flow preventing device is provided with a current detector 13 and a voltage detecting section 21 of a linkage circuit breaker 5 for power supply on a power supply side, a dummy load 18 connected in parallel with a load 9 of a private power generating facility, and a thyristor 23 connected between the loads 9 and 18. The device is also provided with a controller 26, which outputs a generated energy reducing command for reducing the generated energy of a private power generator, by computing generated reversely flowing energy from the current detected by means of the detector 13 and the voltage detected by means of the detecting section, and at the same time, outputs an ignition time reducing command by computing the necessary dummy load quantity based on the reversely flowing generated energy, a governor 25 which controls reduction of the generated energy of the private generator by reducing the field current of the generator, based on the generated energy reducing command from the controller 26, and a phase control circuit 24 which ignites a thyristor based on an igniting command and the igniting time reducing command from the controller 26, and at the same time, controls the igniting time of the thyristor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse power flow prevention device for a private power generation facility installed in, for example, a power consumer, and more particularly to a reverse power flow prevention to a power supply side due to a load change.

[0002]

2. Description of the Related Art In a consumer who consumes a large amount of electric power,
While receiving a certain amount of power from a power company, from the viewpoint of energy saving, diesel engines, gas engines,
Consumers will install rotating machines such as gas turbines independently, generate electricity by rotating generators, and install privately-owned power generation equipment that effectively uses waste heat from these rotating machines. Became. For the interconnection between the generator of the private power generation equipment and the electric power system of the electric power company, necessary equipment measures have been taken to maintain safety in accordance with the "Guidelines for System Interconnection Technology".

FIG. 8 is a single-line diagram showing a conventional reverse power flow prevention device for a private power generation facility in which measures for maintaining safety are taken, and FIG. 9 is a schematic diagram of the reverse power flow prevention device for the private power generation device. 6 is a time chart illustrating an operation procedure. FIG.
, A private power generation facility 2 is connected to a power supply side 1. An electric circuit switch 4 and an interconnection breaker 5 for power supply are connected to the electric line 3 on the power supply side 1.
The first wire branch 3 is extended from the branch point P1.
A private load 9 via a transformer 8 which steps down to a branch line 7 of
Is connected. This load 9 separates the load 9 from the first branch line 7 to prevent danger when a ground fault or the like occurs due to the connection of a circuit breaker, a disconnector or the like inside.

The private power generation facility 2 includes a transformer 8 connected to a first branch line 7 and a load 9 connected to the transformer 8.
And a private interconnection breaker 11 connected to a second branch line 10 branched from the branch point P1, and a private generator 12 connected to the interconnection breaker 11. A system current detecting unit 13 such as a current transformer for detecting a system current flowing in the interconnection breaker 5 is provided in the electric line 3, and a load current flowing in the load 9 in the first branch line 7 is detected. A load current detection unit 14 such as a current transformer is provided.

The second branch line 10 is connected to a power generation current detector 15 such as a current transformer for detecting the power generation current flowing in the private interconnection breaker 11. further,
A third branch line 16 branched from a second branch point P2 provided between the transformer 8 and the load 9 of the first branch line 7 has a dummy 17 such as a resistor or a water resistor via a switch 17. A load 18 is connected in parallel to the load 9. The third branch line 16 is connected to a dummy load current detector 19 such as a current transformer for detecting a dummy load current flowing through the dummy load 18.

The system current detector 13 and the load current detector 14
The generated power detection unit 15 and the dummy load current detection unit 19 are connected to the control device 20. The control device 20 has a function of detecting the occurrence state of the reverse power flow by measuring the system current, the generator current, the load current, and the dummy load current, a power command for outputting a predetermined power generation amount to the private generator 12, and It has a function of outputting a closing / closing command for closing / breaking the switch 17.

Next, the operation of the conventional reverse flow prevention device for private power generation equipment will be described with reference to time charts shown in FIGS. First, the private generator 12 and the power supply side 1
It is assumed that a constant load current is supplied from the system. Under this condition, when the load 9 suddenly decreases and the load current detected by the load current detector 14 changes suddenly from I1 to I2 [FIG. 9A], the control device 20 determines the change in the load current. The situation and the system current detected by the system current detector 13;
Based on the change in the generated current detected by the generated current detection unit 15, it is determined that a reverse power flow has occurred, and a closing command is output to the switch 17 to close the switch 17. Then, a dummy load current that compensates for the change I1-I2 of the load current flows through the dummy load 18 (FIG. 9B).

Thereafter, control device 20 calculates the amount of power to be generated by private generator 12 from the amount of load current I2, and outputs a power command for the power amount to private generator 12 [FIG.
(C)], the power generation amount of the private generator 12 is reduced from P1 to P2 [FIG. 9 (d)]. When the amount of power output from the private generator 12 reaches P2 and stabilizes, the control device 20
Determines that there is no reverse power flow and outputs a cutoff command to cut off the dummy load 18 to the switch 17, and the switch 17 is opened to cut off the flow path to the dummy load 18 and return to the original state. Return.

With this configuration, in the private power generation facility 2 using the private power generator 12 having a slow response to the power command, even if the load 9 suddenly decreases and the load current suddenly decreases, the power generator 12 The surplus energy of the power supply side 1 is absorbed by the dummy load 18 for a certain period of time.
When the reverse power flow power detection relay is provided, for example, the reverse power flow power detection relay operates to open the interconnection breaker 5 for power supply, thereby connecting the power to the system. , Power transmission is not stopped, and the safe and stable operation of the private power generation facility 2 becomes possible.

[0010]

In the conventional reverse flow prevention device for a private power generation facility as described above, the control device 20 determines whether the load current detected by the load current detection unit 14 changes and the system current detection unit 13 determines whether or not the system current detection unit 13 has changed. Since it is determined from the detected system current and the change in the generated current detected by the generated current detection unit 15 that a reverse power flow has occurred, the system current flowing to the power supply interconnection breaker 5 is detected. Not only the system current detection unit 13 that generates the load 9 but also the load current detection unit 14 that detects the load current flowing through the load 9, the generation current detection and detection unit 15 that detects the generation current flowing through the private generator 12, and the dummy load 18.
Load current detector 19 for detecting a load current flowing through
And the like, a plurality of current detection units must be provided, and the circuit configuration is complicated, and the cost is high. Further, when the load current or the like suddenly decreases due to the sudden decrease of the load 9, the control device 20 determines that the reverse power flow is occurring, closes the switch 17 and changes the load current to the dummy load 18. After flowing the dummy load current to make up for the
Without reducing the load amount of the dummy load 18, the control device 20 calculates the amount of power to be generated by the private generator 12 from the amount of the load current A 1, and sends the power command of the generated amount to the private generator 1.
2 and the amount of power generated by the private generator 12 from P1 to P2
Therefore, there is a problem in that control other than the control system of the private generator 12 itself is added, and an excessive load is applied to the generator 12.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is possible to prevent a reverse power flow to the power supply side due to a load change with a simple configuration at low cost, and to provide a long-life private use. It is an object to obtain a reverse flow prevention device for a power generation facility.

[0012]

According to the present invention, there is provided an apparatus for preventing reverse power flow of a private power generation facility, comprising: a power supply connection breaker connected to a power supply side for supplying power; and a power supply connection breaker. A private generator connected to the branch line via a branch line, a private interconnection circuit breaker provided on the branch line, and a private power generator including a private load mainly supplied with power from the private generator, A current detector for detecting a current flowing in the power supply circuit breaker, a voltage detector for detecting a voltage in the power supply circuit breaker, a dummy load connected in parallel to the private load, a private load and a dummy Calculates the reverse power flow generated from the switching element provided between the load and the current detected by the current detector and the voltage detected by the voltage detector, and generates the power generated by the private generator by the reverse flow power. To reduce Outputs the amount reduction command, calculates the required dummy load amount based on the reverse power flow power amount, switches on the command to flow the current to the dummy load corresponding to the dummy load amount, and reduces power generation by the private generator. A control device that outputs a switch-on reduction command to reduce the dummy load amount in accordance with the amount, and controls the field generator current to be reduced by reducing the field current of the private generator based on the power generation reduction command of the control device. The system includes a governor and a switch control circuit that turns on the switching element based on a switch-on command and a switch-on reduction command of the control device and that controls to reduce the switch-on.

According to the present invention, the reverse power flow generated by the control device in the power supply circuit breaker due to a sudden decrease in load power or the like from a change in current detected by the current detection unit and a change in voltage detected by the voltage detection unit. And outputs a power generation reduction command to the governor to reduce the amount of power generated by the private generator by the amount of reverse power flow to the governor, and calculates the required dummy load based on the amount of reverse power flow and calculates the dummy load. A switch-on command for passing a current to the dummy load corresponding to the load and a switch-on reduction command for reducing the dummy load corresponding to the amount of power generated by the private generator are output to the switch control circuit. Based on the energy reduction command, the field current of the private generator is reduced to reduce the amount of power generated by the reverse power flow, and at the same time, the switch control circuit The switching element is turned on based on the switch-on command, the current corresponding to the dummy load amount is passed to the dummy load, and the current flowing to the dummy load is gradually reduced based on the switch-on reduction command. Even if the surplus energy of the private generator is absorbed by the dummy load for a certain period of time, the power will not flow back to the power supply side, so the reverse power flow power detection relay operates to connect the power supply. The power transmission is not stopped by opening the circuit breaker, enabling safe and stable operation of the private power generator, and reducing the load of the dummy load, and controlling the power of the private generator by the governor. Therefore, it is possible to immediately respond to a sudden decrease in the load.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a single-line diagram showing a reverse power flow prevention device for a private power generation facility according to Embodiment 1 of the present invention. FIG. 2 is a waveform diagram showing a firing state of a thyristor of the reverse power flow prevention device for the private power generation device. 4 is a time chart showing an operation procedure of the reverse power flow prevention device of the private power generation equipment. In the figure, the same components as those of the conventional example are denoted by the same reference numerals, and the description of the duplicated components will be omitted. Reference numeral 21 denotes a voltage detection unit provided between the interconnection breaker 5 for power supply of the electric line 3 and the first branch point P1, and detects a voltage at the interconnection breaker 5; A reverse flow power detection relay, which is provided between the supply interconnection breaker 5 and the first branch point P1 and opens the interconnection breaker 5 when reverse power flow power is detected, 23 is a third branch line 16 And a dummy load 1
8 is a thyristor which is a switching element provided before each of them.

A phase control circuit 24 is a switch control circuit for outputting an ignition signal to the gate of the thyristor 23.
Is a governor that controls the amount of power generation by adjusting the field current of the private generator 12, and 26 is a control device, which is generated by measuring the system current flowing through the interconnection breaker 5 and the system voltage at the interconnection breaker 5. Calculated the reverse power flow power amount, outputs a power generation amount reduction command for reducing the power generation amount of the private generator 12 by the reverse power flow power amount, and calculates a necessary dummy load amount based on the reverse power flow power amount, The ignition command is a switch-on command for flowing a current to the dummy load 18 corresponding to the dummy load amount, and the switch-on reduction command is to reduce the dummy load amount in accordance with the power generation amount reduced by the private generator 12. It has a function to output a firing time reduction command for the load current phase. The first embodiment
Does not include the load current detector 14, the generated current detector 15 and the dummy load current detector 19 provided in the conventional example.

Next, the operation of the reverse power flow prevention device for the private power generation equipment according to the first embodiment of the present invention will be described with reference to the time charts of FIGS. 1, 2 and 3. First, it is assumed that a constant load current is supplied to the load 9 from the private generator 12 and the system on the power supply side 1. Under this condition, when the load 9 sharply decreases and the load power sharply decreases from P1 to P2 [FIG. 3 (a)], reverse load power is generated due to the decrease in the load [FIG. 3 (b). )]. Normally, the reverse power flow relay 22 detects the reverse power flow power and detects the reverse power flow, and shuts off the interconnection breaker 5. .2 seconds [Figure 3
(C)]. Since the interruption of the interconnection breaker 5 causes a state in which power transmission is stopped, which is undesirable, it is necessary to put the dummy load 18 within 0.2 seconds after the generation of reverse power flow power.

Therefore, the system current detection unit 13 detects the generation of reverse power flow power and the current change of the system current and the voltage detection unit 21.
The controller 25 determines from the voltage change of the system voltage detected by the control unit that the reverse power flow power is being generated. This reverse power flow power generation determines the power flow power or the reverse power flow power by looking at the phase of the system voltage detected by the voltage detection unit 21 and the phase of the system current detected by the system current detection unit 13. If the control device 26 determines that reverse power flow power is being generated, the control device 26 further calculates the generated reverse power flow power amount and reduces the power generation amount of the private generator 12 by the reverse power flow power amount. A command is output to the governor 25, a required dummy load amount is calculated based on the reverse power flow amount, and a firing command which is a switch-on command for flowing a current to the dummy load 18 corresponding to the dummy load amount is provided. An ignition time reduction command, which is a switch-on reduction command for reducing the dummy load in accordance with the amount of power generated by the private generator 12, is output to the phase control circuit 24, which is a switch control circuit.

The governor 25 receiving the power generation reduction command
Reduces the field current of the private generator 12 to reduce the amount of power generation by the amount of reverse flow power. At the same time, first, the phase control circuit 24, which has received the firing command, outputs a firing signal to the gate of a predetermined thyristor 23 to make the thyristor 23 conductive so that a current flows through the dummy load 18. As described above, the process from the generation of the reverse power flow power to the flow of the current to the dummy load 18 is performed within 0.15 seconds [FIG. 3 (c)]. At this time, the thyristor 23 is conducting in all phases of each cycle [FIG. 2 (a)]. After that, the phase control circuit 24 that has received the firing time reduction command outputs a signal in FIG.
In the order shown in (c), the time to fire is gradually reduced (the range to be fired is narrowed) with respect to the phase of the dummy load current, and the dummy load 18 is substantially gradually reduced.

Further, as shown in FIG.
5, the dummy power of the dummy load 18 gradually decreases as shown in FIG. 3C. Then, when the power generation amount of the private generator 12 becomes stable at the power generation amount P2 corresponding to the load 9 that has rapidly decreased, the control device 26 determines that there is no reverse power flow, and reduces the power generation amount of the private generator 12. A power generation reduction stop command to be reduced is output to the governor 25 and the dummy load 18 is reduced.
Is output to the phase control circuit 24. The governor 25 that has received the power generation reduction stop command stops the reduction of the power generation of the private generator 12, and the phase control circuit 24 that has received the firing stop command outputs a firing stop signal to the gate of the predetermined thyristor 23. Then, the thyristor 23 is turned off and the dummy load 18 is cut off.

In this way, in the private power generation facility 2 using the private power generator 12, even if the amount of load power suddenly decreases due to a sudden decrease in the load 9, the power generator 1 for the private power generator can be used.
2 is absorbed by the dummy load 18 for a certain period of time, so that the power does not flow backward to the system on the power supply side 1, and the power supply relay is operated by the operation of the reverse flow power detection relay 22. The system circuit breaker 5 is not opened to stop power transmission, and the safe and stable operation of the private power generator 2 is enabled. In addition, the load of the dummy load 18 is reduced, Since the power is controlled by the governor 25, it is possible to immediately respond to a sudden decrease in the load 9.

Embodiment 2 FIG. FIG. 4 shows Embodiment 2 of the present invention.
And FIG. 5 is a waveform diagram showing a firing state of a thyristor by cycle control of the reverse power flow prevention device of the private power generation facility. In the second embodiment, a cycle control circuit 34 is used instead of the phase control circuit 24 of the first embodiment. When the control device 26 determines that reverse power flow power is being generated, it outputs a power generation amount reduction command to the governor 25 in the same manner as in the first embodiment, and outputs to the cycle control circuit 34 a firing command that is a switch-on command. An ignition time reduction command for a load current cycle, which is a switch-on reduction command, is output. The governor 25 who received the power generation reduction instruction,
As in the first embodiment, the field current of the private generator 12 is reduced, and the amount of power generation is reduced by the amount of reverse flow power.

At the same time, the cycle control circuit 34, which has received the ignition command for the load current cycle, applies an ignition signal for all load current cycles to the gate of the predetermined thyristor 23 as shown in FIG. , And the thyristor 23 is turned on to supply a current to the dummy load 18.
After that, the cycle control circuit 34 which has received the ignition time reduction command for the load current cycle is controlled by the cycle control circuit 34 shown in FIGS.
, The cycles to be fired are gradually reduced (the range to be fired is narrowed) with respect to the dummy load current cycles, and the dummy load 18 is substantially gradually reduced. Further, as the governor 25 reduces the amount of power generated by the private power generator 12, the dummy power of the dummy load 18 gradually decreases.

When the amount of power generated by the private generator 12 becomes stable with the amount of power P2 commensurate with the load 9 that has sharply decreased, the control device 26 determines that there is no reverse power flow, and The power generation amount reduction stop command for reducing the power generation amount is output to the governor 25, and the ignition stop command for cutting off the dummy load 18 is output to the cycle control circuit 34. The governor 25 that has received the power generation reduction stop command stops the reduction of the power generation of the private power generator 12, and the cycle control circuit 34 that has received the firing stop command outputs a firing stop signal to the gate of the predetermined thyristor 23. Output to thyristor 2
Then, the dummy load 18 is cut off by setting 3 to non-conduction. The second embodiment is different from the first embodiment only in that a cycle control circuit 34 is used instead of the phase control circuit 24, and the operation and effect are the same as those of the first embodiment. Is omitted.

Embodiment 3 FIG. FIG. 6 shows Embodiment 3 of the present invention.
1 is a single-line diagram showing a reverse power flow prevention device for private power generation equipment according to (1). In the third embodiment, a relay contact 43 is used instead of the thyristor 23 as the switching element of the first embodiment (excitation coil of the relay is not shown), and a relay control circuit 44 is used instead of the phase control circuit 24. Things. Further, an incandescent light bulb is used for the dummy load 18 as a resistor. If the control device 26 determines that reverse power flow is occurring, it outputs a power generation amount reduction command to the governor 25 as in the first embodiment, and the relay control circuit 4
4 outputs a relay contact ON command for turning on a predetermined number of relay contacts as a switch ON command and a relay contact number reduction command for decreasing the number of ON relay contacts as a switch reduction command. Governor 2 receiving the power generation reduction order
5 reduces the field current of the private generator 12 in the same manner as in the first embodiment to reduce the amount of power generation by the amount of reverse flow power.

At the same time, the relay control circuit 44, which has received a relay contact ON command to turn on a predetermined number of relay contacts, which is a switch-on command, supplies an exciting current to the exciting coils of the predetermined number of relays to cause a predetermined number of relay contacts. Are conducted, and a current flows through the dummy load 18. Thereafter, the relay control circuit 44, which has received the command to reduce the number of relay contacts to be turned on, which is the switch reduction command, gradually reduces the number of relay contacts to be turned on to substantially reduce the dummy load 18. Gradually decrease. Further, as the governor 25 reduces the amount of power generated by the private power generator 12, the dummy power of the dummy load 18 gradually decreases.

When the amount of power generated by the private generator 12 becomes stable with the amount of power P2 corresponding to the load 9 that has sharply decreased, the control device 26 determines that there is no reverse power flow, and A power generation amount reduction stop command for reducing the power generation amount is output to the governor 25 and a relay contact number reduction stop command for stopping the reduction of the number of relay contacts that are turned on to cut off the dummy load 18 is issued to the relay control circuit 44.
Output to The governor 25 that has received the power generation reduction stop command stops the reduction of the power generation of the private generator 12, and the relay control circuit 44 that receives the relay contact number reduction stop command has supplied the current to the exciting coil of the relay until now. Stop the excitation current and turn off the relay contact to set the dummy load 1
Block 8 The third embodiment differs from the first embodiment only in that a relay control circuit 34 is used instead of the phase control circuit 24 of the first embodiment. Basic operations and effects are the same as those of the first embodiment. Although the description is omitted, unlike the first and second embodiments, an incandescent lamp is used for the dummy resistor 18 and the relay contact 43 is turned on and off, so that the reverse power flow can be absorbed without generating harmonics. There is.

Embodiment 4 FIG. 7 shows Embodiment 4 of the present invention.
It is a waveform diagram explaining operation | movement of the reverse power flow prevention apparatus of the private power generation equipment which concerns on FIG. In the fourth embodiment, a private generator 1
Reference numeral 2 denotes a wind power generator, and when the load 9 is constant and the amount of power generation increases sharply to generate reverse power flow power, the reverse power flow power is absorbed by the dummy load 18. The output characteristics of the wind power generator constantly change depending on the strength of the wind, but as shown in FIGS. 7A and 7B, depending on the condition of the wind, the output twice the rated output may become the instantaneous maximum output. .
At this time, the load 9 described in the first to third embodiments is used.
Unlike the reverse power flow caused by the rapid decrease of the load, the reverse flow power is generated by the load 9 being constant and the power generation amount of the wind power generator abruptly increasing.

When the reverse power flow due to such an instantaneous maximum output occurs, the electric power line 3 on the power supply side 1 and the first branch line 7, the second branch line 10, and the third branch line of the private power generation facility 2 Assuming that the rated output of the wind power generator is 500 KW as the capacity of the 16 distribution lines, for example, as shown in FIG. 7, a capacity of 1000 KW is required, which increases the cost. There was an inconvenience of burden. Therefore, it is an object of the present invention to reduce the cost by reducing the capacity of these distribution lines to 550 KW, which is the allowable capacity when the rated output of the wind power generator is set to 500 KW, for example.

In order to achieve this object, in the fourth embodiment, a threshold value of, for example, 550 KW is set in the control device 26 for the amount of reverse flow power. And the control device 2
6 denotes a current detected by the current detector 13 and a voltage detection unit 21.
Calculates the amount of reverse power flow generated from the detected voltage, and when the amount of reverse power flow reaches a preset threshold value of, for example, 550 KW, the difference between the threshold value of 550 KW and the rated output of 500 KW is calculated. A power generation reduction command is output to the governor 25 to reduce the amount of power generated by the private wind power generator by the amount of reverse power flow of 50 KW, and the necessary dummy load is calculated based on the amount of reverse power flow of power 50 KW. The ignition command, which is a switch-on command for flowing a current to the dummy load 18 corresponding to the dummy load, and the switch-on reduction command, which reduces the dummy load corresponding to the amount of power generated by the private wind power generator, are reduced. A certain ignition time reduction command is output to a phase control circuit 24 which is a switch control circuit.

Then, the governor 25, which has received the power generation amount reduction command, reduces the field current to the private power generator 12 by 50 KW as shown by the dotted line in the output characteristic of the wind power generator in FIG. The amount of power generation is reduced by the amount of reverse power flow. At the same time, first, the phase control circuit 24 which has received the firing command outputs a firing signal to the gate of a predetermined thyristor 23 to make the thyristor 23 conductive and to load the dummy load 1.
8, a current of 50 KW is consumed by the dummy load 18.

Thereafter, the phase control circuit 24, which has received the firing time reduction command, gradually reduces the firing time for the phase of the dummy load current (narrows the firing range). The dummy load 18 is substantially gradually reduced. Further, when the power generation amount of the private power generator 12 decreases to 500 KW of the rated output and becomes stable with the power generation amount corresponding to the load 9, the control device 26 determines that there is no reverse power flow, and A power generation reduction stop command for reducing the power generation amount of the power supply 12 is output to the governor 25 and an ignition stop command for shutting off the dummy load 18 is output to the phase control circuit 24. Governor 2 receiving the power generation reduction stop command
In 5, the reduction of the amount of power generated by the private generator 12 is stopped, and the phase control circuit 24 that has received the firing stop command outputs a firing stop signal to the gate of a predetermined thyristor 23 to make the thyristor 23 non-conductive and to set a dummy The load 18 is shut off.

In this manner, the surplus energy due to the sudden increase in the amount of power generated by the wind power generator, which is the private power generator 12 of the private power generation facility 2, is supplied to the dummy load 18 for a certain period of time.
Does not cause reverse power flow to the power supply side 1 system. In addition, the capacity of the distribution line of the electric power line 3 on the power supply side 1 and the first branch line 7, the second branch line 10 and the third branch line 16 of the private power generation equipment 2 is determined by, for example, the rated output of the wind power generator. When the power is set to 500 KW, the capacity of 550 KW, which is the permissible capacity, is sufficient, and the distribution line does not need to have a large capacity in consideration of the instantaneous maximum output of the wind power generator. Can be reduced. Further, the operation of the reverse power flow power detection relay 22 prevents the interconnection breaker 5 for power supply from being opened to stop the power transmission, thereby enabling the safe and stable operation of the private power generation equipment 2 and the private use. Since power is controlled by the governor 25 for the generator 12,
It is possible to immediately respond to a sudden increase in the amount of power generated by the wind power generator.

In the above description, when the rated output of the wind power generator, which is the private power generator 12, is set to 500 kW, the allowable capacity 550 kW is set as the threshold value of the reverse power flow power of the control device 26. Is 300 kW, the threshold value of the reverse power flow of the controller 26 is 330 kW.
It goes without saying that if the rated output of the wind power generator changes, the threshold value changes. Although the fourth embodiment has been described with reference to the first embodiment in which the switch control circuit is the phase control circuit 24, the second embodiment in which the switch control circuit is the cycle control circuit 34 and the switch control circuit of the fourth embodiment are described. It goes without saying that the third embodiment in which the control circuit is the relay control circuit 44 is also applied.

[0034]

As described above, according to the present invention, the control device sharply decreases the load power from the change in the current detected by the current detection unit and the change in the voltage detected by the voltage detection unit in the power supply circuit breaker. Calculate the amount of reverse power flow generated by
A power generation reduction command is output to the governor to reduce the amount of power generated by the private generator by the reverse power flow, and the necessary dummy load is calculated based on the reverse power flow, and the dummy load corresponding to the dummy load is calculated. A switch-on command for flowing a current to the load and a switch-on reduction command for reducing the dummy load amount corresponding to the power generation amount reduced by the private generator are output to the switch control circuit, and the governor is based on the power generation amount reduction command. Reduce the amount of power generated by the amount of reverse power flow by reducing the field current of the private generator, and at the same time, the switch control circuit turns on the switching element based on the switch-on command and responds to the dummy load to the dummy load And the current flowing to the dummy load is gradually reduced based on the switch-on reduction command. Even if the power is reduced, the surplus energy of the private generator is absorbed by the dummy load for a certain period of time, so that the power does not flow backward to the power supply side. The system breaker is opened, power transmission is not stopped, and safe and stable operation of private power generation equipment is possible.In addition, the amount of dummy load is reduced, and power for private power generators is controlled by the governor. Since the control is performed, there is an effect that it is possible to immediately respond to a sudden decrease in the load.

The private generator is a wind generator,
The control device calculates a reverse flow power amount generated from the current detected by the current detector and the voltage detected by the voltage detector, and when the reverse flow amount reaches a preset threshold,
A power generation reduction command that reduces the amount of power generated by the private wind generator by the amount of reverse power flow of the difference between the threshold value and the rated output of the wind power generator, and the required dummy load based on the amount of reverse power flow power of the difference The switch-on command to calculate the amount and switch the switch-on command to flow the current to the dummy load corresponding to the dummy load amount and the switch-on reduction command to reduce the dummy load amount according to the power generation amount reduced by the private wind power generator Because the power is output to the circuit, the surplus energy due to the sudden increase in the amount of power generated by the wind power generator is absorbed by the dummy load for a certain period of time, so that power does not flow backward to the power supply system. In addition, when the capacity of the distribution line of the power supply side and the private power generation equipment is set to the rated output, the capacity of the distribution line can be the allowable capacity. It is not necessary to prepare a large-capacity power supply that takes into account the power consumption of the wind turbine, which can reduce the cost of distribution lines. Has an effect that it can respond immediately to a rapid increase in

[Brief description of the drawings]

FIG. 1 is a single-line diagram showing a reverse power flow prevention device for a private power generation facility according to Embodiment 1 of the present invention.

FIG. 2 is a waveform diagram showing a firing state of a thyristor by phase control of a reverse power flow prevention device of the private power generation facility.

FIG. 3 is a time chart showing an operation procedure of the reverse power flow prevention device of the private power generation facility.

FIG. 4 is a single-line diagram showing a reverse power flow prevention device for a private power generation facility according to Embodiment 2 of the present invention.

FIG. 5 is a waveform diagram showing a firing state of a thyristor by cycle control of the reverse power flow prevention device of the private power generation facility.

FIG. 6 is a single-line diagram showing a reverse power flow prevention device for a private power generation facility according to Embodiment 3 of the present invention.

FIG. 7 is a waveform diagram illustrating the operation of the reverse power flow prevention device for a private power generation facility according to Embodiment 4 of the present invention.

FIG. 8 is a single-line diagram showing a conventional reverse power flow prevention device for private power generation equipment.

FIG. 9 is a time chart showing an operation procedure of the reverse power flow prevention device of the private power generation facility.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply side 2 Private power generation equipment 3 Electric line 5 Power supply interconnection breaker 9 Private load 10 Second branch line 11 Private interconnection breaker 12 Private generator 13 Current detector 18 Dummy load 21 Voltage detector 23 Thyristor (switching element) 24 Phase control circuit (switch control circuit) 25 Governor 26 Controller

Claims (5)

[Claims] 1. A power supply connection breaker connected to a power supply side for supplying power, a private power generator connected to the power supply connection breaker via a branch line, and a branch line provided A private power supply equipment comprising a private power supply circuit breaker and a private load mainly supplied with power from the private power generator, and a current detector for detecting a current flowing through the power supply power supply circuit breaker; A voltage detector that detects a voltage in the power supply circuit breaker, a dummy load connected in parallel to the private load, a switching element provided between the private load and the dummy load, and a current detector. Calculates the amount of reverse power flow generated from the current and the voltage detected by the voltage detector, outputs a power generation reduction command that reduces the amount of power generated by the private generator by the amount of reverse power flow, and outputs Required Calculates the dummy load amount and outputs a switch-on command to supply current to the dummy load corresponding to the dummy load amount and a switch-on reduction command to reduce the dummy load amount according to the power generation amount reduced by the private generator. A governor that reduces the field current of the private generator based on the power generation reduction command of the control device to reduce the power generation, and switches based on the control device switch-on command and the switch-on reduction command. A reverse power flow prevention device for a private power generation facility, comprising: a switch control circuit for turning on an element and reducing switch-on. 2. The private power generator is a wind power generator,
The control device calculates a reverse flow power amount generated from the current detected by the current detector and the voltage detected by the voltage detection unit, and when the reverse flow amount reaches a preset threshold value, A power generation reduction command that reduces the amount of power generated by the private wind generator by the amount of reverse power flow of the difference between the threshold value and the rated output of the wind power generator, and the required dummy load based on the reverse power flow power of the difference And a switch-on command for flowing a current to the dummy load corresponding to the dummy load amount and a switch-on reduction command for reducing the dummy load amount corresponding to the power generation amount reduced by the private wind power generator. The reverse power flow prevention device for private power generation equipment according to claim 1, wherein the reverse power flow is output to a circuit. 3. The switching device is a thyristor, wherein the switch-on command of the control device is a firing command for a load current phase, the switch-on reduction command is a firing time reduction command for a load current phase, and the switch control circuit 3. A reverse power flow prevention device for a private power generation facility according to claim 1, wherein the device is a phase control circuit. 4. The switch control circuit according to claim 1, wherein the switching element is a thyristor, the switch-on command of the control device is a firing command for a load current cycle, the switch-on reduction command is a firing time reduction command for a load current cycle, 3. The reverse power flow prevention device for private power generation equipment according to claim 1, wherein is a cycle control circuit. 5. The switching element is a relay contact, the switch-on command of the control device is a relay contact-on command, the switch-on reduction command is a relay contact number reduction command, and the switch control circuit is a relay control circuit. The reverse power flow prevention device for a private power generation facility according to claim 1 or 2, wherein: