JP7399124B2 - Self-excited reactive power compensator - Google Patents

Description

Embodiments of the present invention relate to a self-excited reactive power compensator.

BACKGROUND ART Self-excited reactive power compensators are known that are connected to a power grid and output reactive power to the power grid to suppress fluctuations in the voltage of the power grid. The self-excited reactive power compensator is called a self-excited SVC (Static Var Compensator) or a STATCOM (STATic synchronous COMpensator). In the self-excited reactive power compensator, power electronic elements capable of high-frequency switching operations, such as IEGT, GCT, and IGBT, are used in the main circuit.

The device capacity of a self-excited reactive power compensator may reach a large capacity of several megawatts or tens of megawatts. In such a relatively large capacity self-excited reactive power compensator, heat is generated in the main circuit during operation (when the main circuit is energized) due to current loss. Therefore, it is necessary to perform cooling using wind, water, or the like.

On the other hand, when the self-excited reactive power compensator is at rest (the main circuit is not energized), depending on the installation environment, condensation may occur inside the device due to the temperature difference between the air and the device. When condensation occurs inside a self-excited reactive power compensator, moisture can enter structures and components, causing insulation deterioration and component corrosion, which can lead to main circuit malfunctions and failures. be.

In order to suppress condensation when the device is not in operation, there is a method of installing an electric heater called a space heater inside the device (inside the panel) of the self-excited reactive power compensator. When the self-excited reactive power compensator is at rest and the main circuit is not energized, current is passed through the space heater to generate heat. Thereby, by preventing the temperature inside the self-excited reactive power compensator from falling too much, it is possible to suppress the occurrence of dew condensation inside the device.

In addition, a method has been considered in which the self-excited var compensator is operated intermittently for short periods of time while the self-excited var compensator is inactive, thereby generating heat in the main circuit and suppressing the formation of condensation. There is.

However, in the method of providing a space heater, it is necessary to ensure a sufficient physical insulation distance between the main circuit components having a potential and the space heater. Therefore, when a space heater is installed in the device, in addition to the installation space of the space heater, a space corresponding to the insulation distance is required, which increases the size of the entire device and impedes miniaturization of the device. In addition, peripheral circuits such as a power supply (auxiliary power supply) for supplying current to the space heater, its wiring, switching circuits, and a protection circuit in the event of space heater failure are also required, which reduces the number of parts for the self-excited reactive power compensator. This also results in an increase in the number and complexity of the configuration.

Compared to the method of installing a space heater, the method of operating the self-excited reactive power compensator intermittently for short periods of time while the self-excited reactive power compensator is inactive requires an increase in the size of the device, an increase in the number of parts, and a change in the configuration. Complications can be suppressed. On the other hand, by unnecessarily supplying reactive power to the power system while the self-excited reactive power compensator is at rest, there is a possibility that the power system will be adversely affected. For example, there is a possibility that the bus voltage may increase or decrease, or the interconnection point power factor may deteriorate.

Therefore, in a self-excited reactive power compensator, it is desirable to be able to suppress the occurrence of dew condensation inside the device while the device is not in use, while suppressing the increase in size of the device and the adverse effects on the power system.

Japanese Patent Application Publication No. 8-261621

Embodiments of the present invention provide a self-excited reactive power compensator that can suppress the occurrence of dew condensation inside the device while the device is at rest, while suppressing the device's increase in size and adverse effects on the power system.

According to an embodiment of the present invention, the main circuit unit includes a main circuit unit configured to be able to output reactive power to an AC power grid, a control device that controls the operation of the main circuit unit, and an internal space, and the main circuit unit has an internal space. a casing that accommodates a circuit section in the internal space, the main circuit section having a plurality of main circuits, each of the plurality of main circuits having a plurality of self-excited switching elements, By switching the plurality of switching elements, bipolar reactive power of capacitive reactive power and inductive reactive power can be output to the power system, and the control device individually controls the operation of the plurality of main circuits, It has a normal operation operation and a dew condensation prevention operation operation, and the normal operation operation is an operation of supplying capacitive reactive power or inductive reactive power from the main circuit section to the power system, and the The dew condensation prevention operation is performed by outputting capacitive reactive power from one of the plurality of main circuits, outputting inductive reactive power from another one of the plurality of main circuits, and controlling the magnitude of the capacitive reactive power. This is an operation for suppressing condensation from occurring within the housing by controlling the operations of the plurality of main circuits so that the magnitude of the inductive reactive power is the same as the magnitude of the inductive reactive power. The number of circuits is an odd number, and the control device controls one of the plurality of main circuits, a main circuit that outputs capacitive reactive power, and a main circuit that outputs inductive reactive power, in the operation of the dew condensation prevention operation. A self-excited reactive power compensator is provided that temporally changes .

A self-excited reactive power compensator is provided that can suppress the occurrence of dew condensation inside the device while the device is inactive, while suppressing the increase in size of the device and the adverse effects on the power system.

FIG. 1 is a block diagram schematically representing a self-excited reactive power compensator according to an embodiment. 3 is a flowchart schematically representing an example of the operation of the self-excited reactive power compensator according to the embodiment. FIG. 3 is a block diagram schematically representing a modification of the self-excited reactive power compensator according to the embodiment. It is a table that schematically represents an example of the operation of the control device according to the embodiment. 7 is a table schematically showing an example of another operation of the control device according to the embodiment.

Each embodiment will be described below with reference to the drawings.
Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be shown differently depending on the drawing.
In the present specification and each figure, the same elements as those described above with respect to the existing figures are denoted by the same reference numerals, and detailed explanations are omitted as appropriate.

FIG. 1 is a block diagram schematically representing a self-excited reactive power compensator according to an embodiment.
As shown in FIG. 1, the self-excited reactive power compensator 10 includes a main circuit section 12, a control device 14, and a housing 16. The main circuit section 12 is connected to the power system 2. The power system 2 is an AC power system. The AC power of the power system 2 may be single-phase AC power or three-phase AC power.

The main circuit section 12 is configured to be able to output reactive power to the power system 2. The control device 14 is connected to the main circuit section 12. The control device 14 controls the operation of the main circuit section 12. In other words, the control device 14 controls the output of reactive power from the main circuit section 12 to the power system 2 . The housing 16 has a box shape with an internal space, and accommodates the main circuit section 12 and the control device 14 in the internal space. The housing 16 may also be called, for example, a cabinet or an enclosure.

The self-excited reactive power compensator 10 is connected to the power system 2 in close proximity to equipment such as a distributed power source such as solar power generation or wind power generation, an electric railway, or an industrial plant. The self-excited reactive power compensator 10 outputs reactive power to the power system 2, thereby suppressing fluctuations in the voltage of the power system 2 due to the operation of the equipment as described above.

The self-excited reactive power compensator 10 is installed and used outdoors, for example. In other words, the housing 16 is installed outdoors. The main circuit section 12 and the control device 14 are housed in the internal space of the housing 16 and are installed and used outdoors. However, the self-excited reactive power compensator 10 is not necessarily limited to being used outdoors, and may be installed and used indoors.

Note that the connection between the main circuit section 12 and the power system 2 may be via a transformer or the like. The connection between the main circuit section 12 and the power system 2 is not limited to a physical connection such as wiring, but may also be made through a magnetic connection such as a transformer. The form of connection between the main circuit section 12 and the power system 2 may be any form that allows reactive power to be output from the main circuit section 12 to the power system 2. Further, the connection between the main circuit section 12 and the control device 14 is not limited to a physical connection such as wiring, but may be via wireless communication or the like. The form of connection between the main circuit section 12 and the control device 14 may be any form that allows the control device 14 to control the operation of the main circuit section 12.

Further, in this example, the main circuit section 12 and the control device 14 are housed within the same internal space of the casing 16. However, the control device 14 may be housed in a separate housing from the main circuit section 12. The housing 16 only needs to be configured to accommodate at least the main circuit section 12.

The main circuit section 12 has two main circuits, a first main circuit 21 and a second main circuit 22. The first main circuit 21 and the second main circuit 22 are each connected to the power system 2. In other words, the first main circuit 21 and the second main circuit 22 are connected to the power system 2 in parallel. The first main circuit 21 and the second main circuit 22 have a plurality of self-excited switching elements, and output reactive power to the power system 2 by switching the plurality of switching elements. The switching elements of the first main circuit 21 and the second main circuit 22 include high-frequency switching elements such as IEGT (Injection Enhanced Gate Transistor), GCT (Gate Commutated Turn off thyristor), and IGBT (Insulated Gate Bipolar Transistor). A power electronics element capable of this is used.

In this way, the main circuit unit 12 has two main circuits, the first main circuit 21 and the second main circuit 22, and is connected to the power system 2 from each of the first main circuit 21 and the second main circuit 22. Different reactive powers can be output. In the main circuit section 12 configured with self-excited switching elements, capacitive reactive power (leading reactive power) and inductive reactive power (lagging reactive power) are generated from each of the first main circuit 21 and the second main circuit 22. It is possible to output bipolar reactive power to the power system 2.

The first main circuit 21 and the second main circuit 22 output an AC voltage having the same phase as the system voltage of the power system 2 to the power system 2, and make the amplitude of the output AC voltage larger than the system voltage. Thereby, capacitive reactive power can be supplied from the first main circuit 21 and the second main circuit 22 to the power system 2. The first main circuit 21 and the second main circuit 22 output an AC voltage having the same phase as the system voltage of the power system 2 to the power system 2, and make the amplitude of the output AC voltage smaller than the system voltage. Thereby, inductive reactive power can be supplied from the first main circuit 21 and the second main circuit 22 to the power system 2.

The configuration of the second main circuit 22 is the same as the configuration of the first main circuit 21. The device capacity of the second main circuit 22 is, for example, the same as the device capacity of the first main circuit 21. However, the configuration of the second main circuit 22 may be different from the configuration of the first main circuit 21. The configuration of the first main circuit 21 and the configuration of the second main circuit 22 may be any configuration capable of supplying capacitive reactive power and inductive reactive power to the power system 2.

The control device 14 is connected to each of the first main circuit 21 and the second main circuit 22, and individually controls the operation of the first main circuit 21 and the second main circuit 22. More specifically, the control device 14 individually controls the polarity and magnitude (effective value) of the reactive power output from each of the first main circuit 21 and the second main circuit 22.

The control device 14 has a normal operation operation and a dew condensation prevention operation operation. The normal operation is an operation in which capacitive reactive power or inductive reactive power is supplied from the main circuit section 12 to the power system 2. Normal operation is performed by, for example, supplying capacitive reactive power or inductive reactive power from the main circuit section 12 to the power grid 2 in response to fluctuations in the grid voltage of the power grid 2, etc. This is an action to suppress.

During normal operation, the control device 14 outputs reactive power of the same polarity from each of the first main circuit 21 and the second main circuit 22, thereby transmitting capacitive reactive power from the main circuit section 12 to the power system 2. Or output inductive reactive power.

Furthermore, information on the voltage value of the system voltage of the power system 2 is input to the control device 14 from, for example, a voltage detection circuit (not shown) or a higher-level controller. When the voltage value of the grid voltage is lower than a predetermined value, the control device 14 increases the voltage value of the grid voltage by outputting capacitive reactive power from the main circuit section 12 to the power grid 2, and lowers the grid voltage. When the voltage value is higher than a predetermined value, the main circuit section 12 outputs inductive reactive power to the power grid 2 to reduce the voltage value of the grid voltage. Thereby, fluctuations in the system voltage of the power system 2 can be suppressed.

During normal operation, the control device 14 outputs output from the first main circuit 21 and the second main circuit 22 depending on the direction of fluctuation in the grid voltage (whether it is a fluctuation toward a higher side or a fluctuation toward a lower side). The polarity of the reactive power is controlled, and the magnitude of the reactive power output from the first main circuit 21 and the second main circuit 22 is controlled according to the magnitude of fluctuation in the system voltage. In this case, the magnitude of the reactive power output from the second main circuit 22 may be the same as or different from the magnitude of the reactive power output from the first main circuit 21. In normal operation, for example, reactive power may be output to the power system 2 from only one of the first main circuit 21 and the second main circuit 22. Note that the operations during normal operation are not limited to operations that suppress fluctuations in the system voltage of the electric power system 2, and include, for example, operations that apply a gain to the power generation amount of generators on the same bus (P gain control), and It may also be an operation of constant power factor control that controls the power factor of the power factor to be constant. The normal operation may be any operation that supplies capacitive reactive power or inductive reactive power from the main circuit section 12 to the power system 2.

The dew condensation prevention operation is an operation that suppresses dew condensation from occurring within the casing 16. During normal operation, heat is generated due to current loss in the main circuit section 12. Therefore, during normal operation, the air within the casing 16 is warmed by the heat generated from the main circuit section 12. For example, if normal operation is stopped when there is a large temperature difference between the air inside the casing 16 and the air outside the casing 16, such as at night, the temperature inside the casing 16 will change depending on the temperature of the outside air. As the temperature of the air decreases and the amount of saturated water vapor changes, there is a possibility that dew condensation will occur inside the housing 16. Such condensation may cause insulation deterioration, component corrosion, etc., and may cause malfunction or failure of the main circuit section 12. The control device 14 suppresses the occurrence of dew condensation inside the casing 16 by performing a dew condensation prevention operation as necessary during a pause in which normal operation is not performed.

In the dew condensation prevention operation, the control device 14 causes the first main circuit 21 to output capacitive reactive power, the second main circuit 22 to output inductive reactive power, and the first main circuit 21 to output inductive reactive power. The operations of the first main circuit 21 and the second main circuit 22 are controlled so that the magnitude of the capacitive reactive power is the same as the magnitude of the inductive reactive power output from the second main circuit 22. In other words, the control device 14 outputs capacitive reactive power from half of the plurality of main circuits, and outputs inductive reactive power from the other half of the plurality of main circuits, thereby outputting it from the first main circuit 21. The magnitude of the capacitive reactive power is made to be the same as the magnitude of the inductive reactive power output from the second main circuit 22.

By operating the first main circuit 21 and the second main circuit 22 in this way, the air within the housing 16 can be warmed by the heat generated from the first main circuit 21 and the second main circuit 22. Therefore, the temperature of the air inside the housing 16 decreases, and it is possible to suppress the occurrence of dew condensation inside the housing 16.

By outputting capacitive reactive power and inductive reactive power of substantially the same magnitude, the capacitive reactive power and inductive reactive power can be substantially offset within the main circuit section 12, It is possible to suppress output of reactive power to the power system 2. In other words, although current flows through the first main circuit 21 and the second main circuit 22 and generates heat, the current only circulates within the main circuit section 12 and does not substantially flow into the power system 2. Do not leak. More precisely, only the loss (calorific value) due to current flowing through the main circuit section 12 is supplied from the power system 2 side, but the reactive power that causes voltage fluctuation etc. is supplied between the power system 2 and the main circuit section 12. Virtually no occurrence occurs between

As a result, even when the first main circuit 21 and the second main circuit 22 are operated to suppress the occurrence of dew condensation, reactive power is output to the power grid 2, causing adverse effects such as fluctuations in the grid voltage. can be suppressed from being applied to the power system 2.

The control device 14 includes, for example, a condition setting circuit 30, a dew condensation prevention operation circuit 32, a reactive power command circuit 34, and a control circuit 36.

The condition setting circuit 30 is a circuit for setting operating conditions 30a for performing the dew condensation prevention operation. The operating conditions 30a include, for example, judgment conditions for performing dew condensation prevention operation, interlocks, and selection of whether to perform dew condensation prevention operation. Since the dew condensation phenomenon is related to weather conditions and the installation environment, the situation differs depending on each facility where the self-excited reactive power compensator 10 is installed. The setting conditions also differ depending on the device capacity and cooling method of the self-excited reactive power compensator 10. Therefore, in the self-excited reactive power compensator 10, the condition setting circuit 30 individually sets the operating conditions 30a for performing the dew condensation prevention operation.

The condition setting circuit 30 includes, for example, an operation section. The operating condition 30a is set by, for example, an administrator of the self-excited reactive power compensator 10 operating the operating section of the condition setting circuit 30 and manually inputting various information regarding the operating condition 30a. For example, the condition setting circuit 30 may be configured to be able to communicate with an external device such as a mobile terminal such as a smartphone or a host controller, and various information regarding the operating conditions 30a may be input from the external device to the condition setting circuit 30 through communication. Accordingly, the operating condition 30a may be set. In other words, the condition setting circuit 30 may be a communication device that communicates with external equipment. The method for setting the operating condition 30a in the condition setting circuit 30 is not limited to these, and may be any method that can appropriately set the operating condition 30a.

The operating condition 30a may be, for example, during the humid rainy season, when the main circuit section 12 is stopped for more than an hour, and for 10 minutes every two hours, the current is set at 10% of the rated current. The conditions for the dew condensation prevention operation are set, such as "energizing the first main circuit 21 and the second main circuit 22."

In this way, the operating condition 30a is set, for example, based on the elapsed time during which the main circuit section 12 is not performing normal operation. In other words, the operating conditions 30a include the conditions of the elapsed time during suspension. The operating conditions 30a are not limited to this, and may further include, for example, a condition of a temperature difference between the temperature of the air inside the casing 16 and the temperature of the outside air. For example, the operating conditions 30a may be set so that the dew condensation prevention operation is performed only when the temperature difference between the inside and outside air is large. However, the operating conditions 30a are not limited to these, and may be any conditions that require dew condensation prevention operation. In addition, the magnitude of the reactive power output from the first main circuit 21 and the second main circuit 22 during the dew condensation prevention operation may be a predetermined magnitude, or may be determined according to the temperature difference between the inside and outside air. It may also be changed. For example, if the temperature difference is large, the amount of reactive power output during the condensation prevention operation is increased, and if the temperature difference is small, the amount of reactive power output during the condensation prevention operation is decreased. do. Thereby, it is possible to more appropriately suppress the occurrence of dew condensation, and when the temperature difference is small, it is possible to suppress the power consumption due to the dew condensation prevention operation.

The condition setting circuit 30 stores the set operating conditions 30a. The condition setting circuit 30 is connected to a dew condensation prevention operation circuit 32. The condition setting circuit 30 inputs the set operating conditions 30a to the dew condensation prevention operating circuit 32.

The dew condensation prevention operating circuit 32 determines whether the operating condition 30a input from the condition setting circuit 30 is satisfied. For example, when the main circuit section 12 is inactive, the dew condensation prevention operation circuit 32 determines whether the operating condition 30a is satisfied based on the elapsed time during which the main circuit section 12 is inactive. As described above, when the operating conditions 30a include a temperature difference condition, for example, by inputting information regarding the temperature difference from a temperature sensor or a higher-level controller to the dew condensation prevention operation circuit 32, the temperature difference condition can be set. What is necessary is to have the dew condensation prevention operation circuit 32 determine whether or not this is true.

The dew condensation prevention operation circuit 32 inputs an instruction to execute the dew condensation prevention operation to the reactive power command circuit 34 when it is determined that the operation condition 30a is satisfied. The instruction to execute the dew condensation prevention operation includes, for example, information that causes the first main circuit 21 to output capacitive reactive power and the second main circuit 22 to output inductive reactive power, and information about the magnitude of each reactive power. including.

The reactive power command circuit 34 generates a reactive power command for each of the first main circuit 21 and the second main circuit 22 in response to the input of the instruction to execute the dew condensation prevention operation from the dew condensation prevention operation circuit 32. A reactive power command is input to the control circuit 36. For example, the reactive power command circuit 34 is a reactive power command circuit for causing the first main circuit 21 to output capacitive reactive power of a magnitude corresponding to the instruction based on information included in the instruction input from the dew condensation prevention operation circuit 32. In addition to generating a power command, a reactive power command for causing the second main circuit 22 to output inductive reactive power having a magnitude corresponding to the command is generated and input to the control circuit 36 .

During normal operation, for example, information on the voltage value of the grid voltage of the power grid 2 is input to the reactive power command circuit 34, and a reactive power command for suppressing voltage fluctuations in the grid voltage is sent to the reactive power command circuit 34. is inputted to the control circuit 36 from.

The control circuit 36 includes a first output control circuit 41 that controls the operation of the first main circuit 21 and a second output control circuit 42 that controls the operation of the second main circuit 22. The control circuit 36 inputs the reactive power command for the first main circuit 21 input from the reactive power command circuit 34 to the first output control circuit 41, and inputs the reactive power command for the second main circuit 22 input from the reactive power command circuit 34 to the first output control circuit 41. The reactive power command is input to the second output control circuit 42.

The first output control circuit 41 generates a control signal according to the input reactive power command, and inputs the generated control signal to the first main circuit 21, thereby controlling the reactive power according to the reactive power command to the first output control circuit 41. It is output to the main circuit 21. Similarly, the second output control circuit 42 generates a control signal according to the input reactive power command, and inputs the generated control signal to the second main circuit 22, thereby generating reactive power according to the reactive power command. is output to the second main circuit 22.

As a result, in the dew condensation prevention operation, capacitive reactive power according to the setting of the operating condition 30a is output from the first main circuit 21, and inductive reactive power of substantially the same magnitude is output from the second main circuit 21. While suppressing the output of reactive power output from the circuit 22 to the power system 2, the occurrence of dew condensation within the housing 16 is suppressed. During normal operation, capacitive reactive power or inductive reactive power is output from each of the first main circuit 21 and the second main circuit 22 in response to fluctuations in the grid voltage, etc. suppressed.

In this example, the condensation prevention operation circuit 32 determines whether or not to perform the dew condensation prevention operation based on the operating conditions 30a set by the condition setting circuit 30. For example, without being limited to this, the judgment as to whether or not to perform dew condensation prevention operation is made by an external device such as a host controller, and by inputting a command from the external device to the dew condensation prevention operation circuit 32. An instruction to execute the dew condensation prevention operation may be input to the reactive power command circuit 34 based on a command from the device. In this case, the condition setting circuit 30 can be omitted. The configuration of the control device 14 is not limited to the above, and may be any configuration that can appropriately perform normal operation and dew condensation prevention operation.

FIG. 2 is a flowchart schematically showing an example of the operation of the self-excited reactive power compensator according to the embodiment.
As shown in FIG. 2, in the self-excited reactive power compensator 10, the operating condition 30a is first set by the condition setting circuit 30 (step S101 in FIG. 2). The set operating conditions 30a are stored in the condition setting circuit 30 and are input to the dew condensation prevention operating circuit 32.

The dew condensation prevention operating circuit 32 determines whether the operating condition 30a input from the condition setting circuit 30 is satisfied (step S102 in FIG. 2). Then, in response to determining that the operating condition 30a is satisfied, the dew condensation prevention operation circuit 32 inputs an instruction to execute the dew condensation prevention operation to the reactive power command circuit 34 (step S103 in FIG. 2). In this manner, the control device 14 stores the operating condition 30a, and performs the dew condensation prevention operation when the operating condition 30a is satisfied during a pause in which normal operation is not performed.

The reactive power command circuit 34 is a reactive power command circuit for causing the first main circuit 21 and the second main circuit 22 to output reactive power of opposite polarity in response to an input of an instruction to execute the dew condensation prevention operation from the dew condensation prevention operation circuit 32. A power command is generated, and the generated reactive power command is input to the control circuit 36 (step S104 in FIG. 2).

The first output control circuit 41 of the control circuit 36 generates a control signal according to the input reactive power command, and inputs the generated control signal to the first main circuit 21 (step S105 in FIG. 2). The first main circuit 21 outputs capacitive reactive power according to the input reactive power command (step S106 in FIG. 2).

The second output control circuit 42 of the control circuit 36 generates a control signal according to the input reactive power command, and inputs the generated control signal to the second main circuit 22 (step S107 in FIG. 2). The second main circuit 22 outputs inductive reactive power according to the input reactive power command (step S108 in FIG. 2).

The second main circuit 22 outputs inductive reactive power having substantially the same magnitude as the capacitive reactive power output from the first main circuit 21 based on the input reactive power command. Thereby, in the self-excited reactive power compensator 10, it is possible to suppress the output of reactive power to the power system 2 and to suppress the occurrence of dew condensation within the housing 16. Further, there is no need to add other members such as a space heater to suppress the occurrence of dew condensation, and it is possible to suppress an increase in the size of the device, an increase in the number of parts, and a complicated configuration. Therefore, in the self-excited reactive power compensator 10 according to the present embodiment, it is possible to suppress the occurrence of dew condensation inside the device (inside the housing 16) when the device is not in use, while suppressing the increase in size of the device and the negative impact on the power system. It is desirable that

FIG. 3 is a block diagram schematically showing a modification of the self-excited reactive power compensator according to the embodiment.
As shown in FIG. 3, in the self-excited reactive power compensator 10a, the main circuit section 12a further includes a third main circuit 23, and the control circuit 36 of the control device 14a further includes a third output control circuit 43. have Components that are substantially the same in function and configuration as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The configuration of the third main circuit 23 is, for example, the same as the configuration of the first main circuit 21 and the configuration of the second main circuit 22. Each of the first main circuit 21 to third main circuit 23 may have an arbitrary structure capable of supplying capacitive reactive power and inductive reactive power to the power system 2.

In the control device 14a, for example, the reactive power command circuit 34 adjusts the reactive power to each of the first main circuit 21 to the third main circuit 23 in response to an instruction to execute the dew condensation prevention operation from the dew condensation prevention operation circuit 32. A command is generated, and the generated reactive power command is input to the control circuit 36. The third output control circuit 43 generates a control signal according to the input reactive power command, and inputs the generated control signal to the third main circuit 23 to output reactive power according to the reactive power command to the third main circuit 23. It is output to the main circuit 23.

During normal operation, the control device 14a controls the polarity of the reactive power output from each of the first main circuit 21 to the third main circuit 23 according to the direction of fluctuation in the grid voltage, and also The magnitude of reactive power output from each of the first to third main circuits 21 to 23 is controlled depending on the magnitude of the fluctuation.

For example, in the dew condensation prevention operation, the control device 14a causes the first main circuit 21 to output capacitive reactive power, the second main circuit 22 and the third main circuit 23 to output inductive reactive power, and The first main circuit 21 to The operation of the third main circuit 23 is controlled.

For example, in the dew condensation prevention operation, the control device 14a causes the first main circuit 21 to output capacitive reactive power of 1 megabar and outputs 0.5 megabar from each of the second main circuit 22 and the third main circuit 23. outputs inductive reactive power. This makes the magnitude of the inductive reactive power output from the second main circuit 22 and the third main circuit 23 substantially the same as the magnitude of the capacitive reactive power output from the first main circuit 21, and the above example Similarly, while suppressing the output of reactive power to the power system 2, it is possible to suppress the occurrence of dew condensation within the casing 16. Note that, contrary to the above, inductive reactive power may be outputted from the first main circuit 21, and capacitive reactive power may be outputted from the second main circuit 22 and the third main circuit 23.

FIG. 4 is a table schematically showing an example of the operation of the control device according to the embodiment.
As shown in FIG. 4, the control device 14a has, for example, a first state in which capacitive reactive power is output from the first main circuit 21 and a second state in which capacitive reactive power is output from the second main circuit 22. , and a third state in which capacitive reactive power is output from the third main circuit 23. In addition, in FIG. 4, for convenience, capacitive reactive power is represented as a positive value, and inductive reactive power is represented as a negative value.

For example, the control device 14a sequentially switches between the first state, the second state, and the third state at a predetermined timing in the dew condensation prevention operation. For example, the control device 14a sets the first state at the start of the dew condensation prevention operation, switches to the second state when a predetermined time has elapsed since the setting of the first state, and switches it to the second state when a predetermined time has elapsed since the setting of the second state. The state is switched to the third state accordingly, and the state is switched back to the first state when a predetermined time has elapsed since the setting of the third state. In this way, the control device 14a sequentially switches between the first state, the second state, and the third state every predetermined time period, for example, in the dew condensation prevention operation.

For example, as in the first state shown in FIG. When inductive reactive power is output, the heat generated in the first main circuit 21 becomes larger than the heat generated in the second main circuit 22 and the heat generated in the third main circuit 23.

Therefore, in the dew condensation prevention operation, the control device 14a sequentially switches between the first state, the second state, and the third state at a predetermined timing. When the number of the plurality of main circuits is odd, the control device 14a changes over time the main circuit that outputs capacitive reactive power and the main circuit that outputs inductive reactive power among the plurality of main circuits. let As a result, even when three main circuits are provided in the main circuit section 12a and the magnitude of reactive power output from each main circuit is uneven, unevenness in heat generation in each main circuit is suppressed. be able to.

Note that the timing for switching each state is not necessarily limited to the passage of a predetermined time. For example, each state may be switched at the timing when the temperature difference between each main circuit reaches a predetermined value or more. Further, the initial setting may be predetermined, and for example, the initial setting may be such that the main circuit with the largest temperature difference from the outside temperature at the start of the condensation prevention operation outputs a large reactive power. You may also set the status of

FIG. 5 is a table schematically showing another example of the operation of the control device according to the embodiment.
As shown in FIG. 5, in this example, the control device 14a sets the polarity and magnitude of the reactive power output from the first main circuit 21 to sin t, and sets the polarity and magnitude of the reactive power output from the second main circuit 22 to sin t. The polarity and magnitude are set to sin (t-2π/3), and the polarity and magnitude of the reactive power output from the third main circuit 23 are set to sin (t+2π/3). Note that t is the elapsed time from the timing of starting the dew condensation prevention operation. In this example, similarly to FIG. 4, the capacitive reactive power is a positive value, and the inductive reactive power is a negative value. For example, as shown in FIG. 5, when t=90 seconds, sin90°=1, 1 megabar capacitive reactive power is output from the first main circuit 21, and sin-30°=-0.5. , 0.5 megabar of inductive reactive power is output from the second main circuit 22, sin210°=−0.5, and 0.5 megabar of inductive reactive power is output from the third main circuit 23. In this way, by changing the polarity and magnitude of the output reactive power in a sinusoidal manner, the magnitude of the output capacitive reactive power can be made substantially the same as the magnitude of the inductive reactive power. .

In this way, the polarity and magnitude of the reactive power output from each of the first main circuit 21 to the third main circuit 23 are changed in a sinusoidal manner, and the magnitude of the output capacitive reactive power is equal to that of the inductive reactive power. The size may be substantially the same. This makes it possible to more reliably suppress the occurrence of uneven heat generation in each main circuit.

For example, as shown in FIG. 5, the phase of sinusoidal reactive power output from a plurality of main circuits is shifted according to the number of main circuits. More specifically, when the number of main circuits is n, the phases of the sinusoidal reactive powers output from the plurality of main circuits are shifted by 2π/n. In the example of FIG. 5, since there are three main circuits, the phase is shifted by 2π/3 (120°). As a result, while changing the polarity and magnitude of the reactive power output from the plurality of main circuits in a sinusoidal manner, the magnitude of the output capacitive reactive power can be made substantially the same as the magnitude of the inductive reactive power. I can do it. For example, when the number of main circuits is two, by shifting the phase by 180 degrees, the polarity and magnitude of the output reactive power can be changed in a sine wave shape, and the magnitude of the output capacitive reactive power can be changed. , may be substantially the same as the magnitude of the inductive reactive power.

In this way, the number of main circuits provided in the main circuit section 12a is not limited to two, and may be three. When the number of main circuits provided in the main circuit section 12a is three, for example, as in the example shown in FIG. 4, the main circuits that output capacitive reactive power may be sequentially switched at a predetermined timing, As shown in the example shown in Figure 5, the main circuit outputs capacitive reactive power and inductive reactive power by changing the polarity and magnitude of the reactive power output from the main circuit in a sinusoidal manner. It is preferable to temporally change the main circuits in which the power is generated to suppress uneven heat generation in each main circuit.

Further, the number of main circuits provided in the main circuit section 12a may be three or more. The number of main circuits provided in the main circuit section 12a may be an even number or an odd number.

When the number of main circuits is even, as in the case of two, the control device outputs capacitive reactive power from half of the plurality of main circuits and outputs inductive reactive power from the other half of the plurality of main circuits. It is preferable to output.

When the number of main circuits is an odd number, as in the case of three main circuits, the control device sequentially switches the main circuits that output capacitive reactive power at a predetermined timing, and changes the polarity of the reactive power output from the main circuits. The main circuit that outputs capacitive reactive power and the main circuit that outputs inductive reactive power are changed over time by changing the power and magnitude in a sinusoidal manner, and the heat generation in each main circuit is biased. It is preferable to suppress the occurrence of. Further, the method of temporally changing the main circuit that outputs capacitive reactive power and the main circuit that outputs inductive reactive power is not limited to the above. For example, the polarity and magnitude of the reactive power output from the main circuit may be changed over time by changing in a triangular waveform. The method of temporally changing the main circuit that outputs capacitive reactive power and the main circuit that outputs inductive reactive power is such that the magnitude of capacitive reactive power and the magnitude of inductive reactive power are substantially the same. However, any method that can temporally change the main circuit that outputs reactive power of each polarity may be used.

The configuration of the main circuit section may be any configuration that includes a plurality of main circuits and is capable of outputting capacitive reactive power and inductive reactive power from each of the plurality of main circuits. The configuration of the control device is to output capacitive reactive power from one of the plurality of main circuits provided in the main circuit section, output inductive reactive power from another one of the plurality of main circuits, and output capacitive reactive power from one of the plurality of main circuits provided in the main circuit section. Any configuration may be used in which the operations of the plurality of main circuits are controlled so that the magnitude of the reactive power is the same as the magnitude of the inductive reactive power. For example, when the number of main circuits provided in the main circuit section is three, capacitive reactive power is output from one of the three main circuits, and capacitive reactive power is output from another one of the three main circuits. Inductive reactive power may be output from one of the main circuits, and the remaining main circuit may be put into a rest state.

Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

2... Power system, 10, 10a... Self-excited reactive power compensator, 12, 12a... Main circuit section, 14, 14a... Control device, 16... Housing, 21... First main circuit, 22... Second main circuit, 23...Third main circuit, 30...Condition setting circuit, 30a...Operating condition, 32...Dew condensation prevention operation circuit, 34...Reactive power command circuit, 36...Control circuit, 41...First output control circuit, 42...Second output Control circuit, 43...Third output control circuit

Claims (5)

a main circuit section configured to be able to output reactive power to an AC power system;
a control device that controls the operation of the main circuit section;
a casing having an internal space and accommodating the main circuit section in the internal space;
Equipped with
The main circuit section has a plurality of main circuits,
Each of the plurality of main circuits has a plurality of self-excited switching elements, and outputs bipolar reactive power of capacitive reactive power and inductive reactive power to the power system by switching the plurality of switching elements. I can,
The control device individually controls operations of the plurality of main circuits, and has normal operation operation and dew condensation prevention operation operation,
The normal operation is an operation of supplying capacitive reactive power or inductive reactive power from the main circuit section to the power system,
The operation of the dew condensation prevention operation includes outputting capacitive reactive power from one of the plurality of main circuits, outputting inductive reactive power from another one of the plurality of main circuits, and outputting capacitive reactive power from one of the plurality of main circuits. An operation of suppressing dew condensation from occurring within the casing by controlling the operation of the plurality of main circuits so that the magnitude is the same as the magnitude of the inductive reactive power ,
The number of the plurality of main circuits is an odd number,
The control device is a self-excited type that temporally changes a main circuit that outputs capacitive reactive power and a main circuit that outputs inductive reactive power among the plurality of main circuits in the operation of the dew condensation prevention operation. Reactive power compensator. The self-excited reactive according to claim 1 , wherein the control device temporally changes the main circuit that outputs the capacitive reactive power and the main circuit that outputs the inductive reactive power by sequentially switching at a predetermined timing. Power compensator. The control device temporally changes the main circuit that outputs the capacitive reactive power and the main circuit that outputs the inductive reactive power by changing the polarity and magnitude of the reactive power in a sinusoidal manner. The self-excited reactive power compensator according to item 1 . a main circuit section configured to be able to output reactive power to an AC power system;
a control device that controls the operation of the main circuit section;
a casing having an internal space and accommodating the main circuit section in the internal space;
Equipped with
The main circuit section has a plurality of main circuits,
Each of the plurality of main circuits has a plurality of self-excited switching elements, and outputs bipolar reactive power of capacitive reactive power and inductive reactive power to the power system by switching the plurality of switching elements. I can,
The control device individually controls operations of the plurality of main circuits, and has normal operation operation and dew condensation prevention operation operation,
The normal operation is an operation of supplying capacitive reactive power or inductive reactive power from the main circuit section to the power system,
The operation of the dew condensation prevention operation includes outputting capacitive reactive power from one of the plurality of main circuits, outputting inductive reactive power from another one of the plurality of main circuits, and outputting capacitive reactive power. An operation of suppressing dew condensation from occurring within the casing by controlling the operation of the plurality of main circuits so that the magnitude is the same as the magnitude of the inductive reactive power,
The control device stores operating conditions for performing the dew condensation prevention operation, and is configured to automatically perform the dew condensation prevention operation when the operation condition is satisfied during a pause in which the normal operation is not performed . Excited reactive power compensator. 5. The self-excited reactive power compensator according to claim 4 , wherein the operating conditions are set based on the elapsed time during the pause period during which the normal operation is not performed.

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