JP2012143076A - Control method and control apparatus of wind power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method and a control apparatus of a wind power generation system which performs highly reliable ferroresonance detection and effectively prevents adverse effects on an electric power system during the ferroresonance.SOLUTION: A wind power generation system (100) supplies power generated by a wind power generation apparatus (1) to an electric power system (7) through a transformer (11). A control method of the invention includes a process in which the occurence of ferroresonance is detected, a process in which a protection circuit (30) is connected with the wind power generation apparatus (1) when the ferroresonance is detected, and a process in which the wind power generation apparatus (1) is disconnected from the electric power system (7) when the ferroresonance is detected over a first predetermined period T1 after the protection circuit is connected.

Description

  The present invention relates to a control method for a wind power generation system that supplies power generated by a wind power generation apparatus to an electric power system via a transformer, and a technical field of the control apparatus.

  2. Description of the Related Art Conventionally, a wind power generation system that supplies electric power generated by a wind power generator to an electric power system via a transformer is known. In this type of wind power generation system, the transmission distance may reach a long distance depending on the area where the wind power generator is installed. When the power transmission distance is long, the impedance of the power transmission line increases, and thus there is a problem that the power transmission capacity decreases. In order to prevent such a reduction in transmission efficiency, an inductance component included in the transmission line is canceled out by installing a compensation capacitor in series with the transmission line, thereby improving the transmission capacity.

  When a compensation capacitor is installed in this way, iron resonance, which is a kind of nonlinear resonance, may occur due to a correlation with a saturable inductance component having an iron core with magnetic saturation characteristics such as a transformer. The voltage and current due to iron resonance have a lower frequency than the frequency of the power system (commercial fundamental frequency). When iron resonance occurs in this manner, there is a problem that overvoltage or overcurrent is generated inside the wind power generation system, and the internal equipment is damaged. For this reason, when iron resonance occurs in a wind power generation system, it is required to detect the occurrence of iron resonance early and reliably.

  With regard to such a method for detecting iron resonance, for example, Patent Document 1 discloses a technique in which a detected voltage value is converted into a signal by switching ON / OFF with a comparator, and iron resonance is detected by logic processing. Non-Patent Document 1 discloses a protection circuit for attenuating iron resonance by connecting to an electric power system when iron resonance occurs.

US Pat. No. 6,157,552

IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 20, NO. 2, JUNE 2005

  However, in Patent Document 1, since it is necessary to install a logic circuit such as a comparator in order to convert the detection voltage into a signal, there is a problem that the iron resonance detection circuit becomes complicated and cannot be easily implemented.

  The present invention has been made in view of the above problems, and has an object to provide a control method and a control device for a wind power generation system that can effectively prevent an adverse effect at the time of occurrence of iron resonance with a relatively simple configuration. And

  In order to solve the above problems, a method for controlling a wind power generation system according to the present invention is a method for controlling a wind power generation system that supplies power generated by a wind power generation apparatus to an electric power system via a transformer. A detection step of detecting the occurrence of iron resonance in the case, and a protection circuit connection step of connecting a protection circuit for reducing overvoltage or current generated by the iron resonance to the wind power generator when the iron resonance is detected; And a disconnecting step of disconnecting the wind power generator from the power system when an iron resonance is detected over a first predetermined period after the protection circuit is connected to the wind power generator. It is characterized by that.

  According to the method for controlling a wind power generation system according to the present invention, when iron resonance is detected, the protection circuit is connected to the wind power generation device by controlling the first connection means. Thereby, the bad voltage to the apparatus in a wind power generation system can be prevented by reducing the overvoltage or overcurrent which arise in an electric power system by iron resonance with a protection circuit. In addition, after the protection circuit is connected, when the iron resonance is detected for the first predetermined period or longer, the wind power generator is disconnected from the power system by controlling the second connection means. As a result, even if iron resonance has occurred over a long period of time, the wind turbine generator itself can be disconnected from the power system to avoid overloading the protection circuit and adversely affect the wind turbine system. Can be prevented.

  Preferably, after the wind turbine generator is disconnected from the power system, the iron generator is disconnected from the power grid when no iron resonance is detected for a second predetermined period or longer. It is preferable to further include a returning process. In this case, when the iron resonance is not detected for the second predetermined period or longer, the wind power generator is returned to the power system on the assumption that the iron resonance has been completely eliminated. The generation condition of the iron resonance is caused by various factors, and depending on the condition, there may be an unstable behavior such as repeated generation and stop (that is, intermittent behavior). In this aspect, when there is no occurrence of iron resonance during the second predetermined period, it is determined that the iron resonance has been completely eliminated, so that the second connection means is provided in accordance with the iron resonance that occurs intermittently. Can be prevented from being complicatedly switched. Since the electric power generated by the wind power generator flows through the second connecting means, if the switching operation is performed unnecessarily and the contact resistance increases, the amount of heat generated at the location increases, leading to failure. In view of this, in this aspect, it is possible to perform control so that the wind turbine generator can be recovered early without the need to unnecessarily increase the switching operation of the second connection means and after the iron resonance is resolved. it can.

  In one aspect of the present invention, the detecting step calculates a magnetic flux from a time integral value of the voltage applied to the transformer, and detects the occurrence of iron resonance when the magnetic flux exceeds a predetermined level value. In this case, the voltage applied to the transformer may be detected, or alternatively, a voltage generated in the coil by winding a magnetic flux detection coil around the iron core of the transformer. In another aspect, the detection step detects leakage magnetic flux in the transformer, and detects occurrence of iron resonance when the detected leakage magnetic flux exceeds a predetermined level value. In still another aspect, the detecting step extracts a low-frequency component of a voltage waveform or a current waveform in the transformer transformer through a low-pass filter, and the iron resonance occurs when the output waveform of the low-pass filter exceeds a predetermined level value. Detects the occurrence of By providing such a detection process, the present invention can detect iron resonance having a frequency lower than the commercial fundamental frequency with high reliability.

  The wind power generation system may be configured by connecting a plurality of wind power generation devices connected in parallel to the power system via the transformer. As described above, when a plurality of wind turbine generators connected in parallel to each other are connected to the power system via one or more transformers, the detection means detects the occurrence of iron resonance in the plurality of wind turbine generators. This can also be detected by monitoring the transformer.

  In this case, when the iron resonance is detected over the first predetermined period or more in the disconnecting step, the plurality of wind turbine generators are combined until the iron resonance is eliminated. It is good to disconnect from the electric power system every predetermined time. According to this, since it is not necessary to disconnect a plurality of wind power generators all at once, power is generated by the remaining wind power generators while disconnecting some of the wind power generators to suppress iron resonance. Thus, the power supply to the power system can be continued.

  In order to solve the above problems, a control device for a wind power generation system according to the present invention is a control device for a wind power generation system that supplies electric power generated by a wind power generation device to an electric power system via a transformer. Detecting means for detecting the occurrence of iron resonance in the wind turbine generator, and a first protection circuit for switching the connection state of the protection circuit capable of suppressing overvoltage or current generated by iron resonance by connecting to the wind turbine generator. A connection means, a second connection means for switching the connection state of the wind turbine generator to the power system, and the protection circuit is connected to the wind turbine generator when an iron resonance is detected by the detector. The first connecting means is controlled at the same time, and thereafter, when the iron resonance is detected by the detecting means over a first predetermined period or longer, the wind power generation is performed. The device is characterized in that a control means for controlling said second connection means so as to disconnection from the power grid.

  In particular, when the wind power generation system is configured by connecting a plurality of the wind power generation devices connected in parallel to the power system via the transformer, the control means includes the detection means. When the iron resonance is detected over the first predetermined period, the plurality of wind turbine generators are disconnected from the power system one by one every predetermined time until the iron resonance is canceled. Good.

  The control apparatus for a wind power generation system according to the present invention can be suitably realized by the above-described wind power generation system control method (including the above-described various aspects).

  According to the present invention, when iron resonance is detected, the protection circuit is connected to the wind turbine generator by controlling the first connecting means. Thereby, the bad influence to a wind power generation system can be prevented by reducing the overvoltage or overcurrent which arise in an electric power system by iron resonance in a protection circuit. In addition, after the protection circuit is connected, when the iron resonance is detected for the first predetermined period or longer, the wind power generator is disconnected from the power system by controlling the second connection means. Thereby, even if it is a case where iron resonance occurs over a long period of time, it can avoid that a protection circuit falls into an overload state by separating the wind power generator itself from the electric power system.

It is a block diagram which shows notionally the whole structure of the wind power generation system which concerns on 1st Example. It is a block diagram which shows notionally the structure at the time of applying the wind power generation system which concerns on 1st Example to a full converter system. It is a flowchart figure which shows the control content of the wind power generation system which concerns on 1st Example. It is a flowchart figure which shows the detection method of the iron resonance in step S101 and S104 of FIG. It is a block diagram which shows notionally the whole structure of the wind power generation system which concerns on 2nd Example. It is a flowchart figure which shows the detection method of the iron resonance in the wind power generation system which concerns on 2nd Example. It is a block diagram which shows notionally the whole structure of the wind power generation system which concerns on 3rd Example. It is a block diagram which shows notionally the whole structure of the wind power generation system which concerns on 4th Example. It is a flowchart figure which shows the control content of the wind power generation system which concerns on 5th Example.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

[First embodiment]
First, the overall configuration of the wind power generation system 100 according to the first embodiment will be described with reference to FIG. FIG. 1 is a block diagram conceptually showing the overall structure of the wind power generation system 100 according to the first embodiment.

  The wind power generator 1 has a rotor to which a plurality of windmill blades are attached, and the rotor is connected to a generator 11 via a speed increaser. The bus 13 connected to the output terminal of the generator 11 is connected to the system connection end 6 of the system interconnection unit 4 via the changeover switch SW1, the transformer 12, and the changeover switch SW2. The change-over switches SW1 and SW2 are examples of the “second connecting means” in the present invention. As described above, in the wind turbine generator 1, the rotation of the windmill blade is input to the generator 11 through the speed increaser. After the power generated by the generator 11 is transformed by the transformer 12, the grid interconnection unit 4 is changed. Via the power system 7. In the example of FIG. 1, the generator 11 is an induction generator, and a variable speed operation is enabled by connecting a converter 20 that converts the frequency between the connection 14 to the rotor winding of the generator 11 and the bus 13. Yes. Thus, in this embodiment, a so-called double-fed system is adopted.

  The control method according to the present invention is also applicable to a so-called full converter system in which generator outputs such as induction machines and synchronous machines are connected to the power system 7 via the converter 20 as a system other than the double-fed system. This is also possible, and the same applies to Examples 2 to 4 below. FIG. 2 shows an example in which the wind power generation system 100 according to the first embodiment is realized by the full converter method. In FIG. 2, the same reference numerals are assigned to portions common to FIG. 1, and will be described together with FIG. 1.

  Returning to FIG. 1 again, the wind turbine generator 1 is provided with a crowbar circuit 30 which is a protection circuit for reducing an overvoltage or overcurrent generated when iron resonance occurs. The crowbar circuit 30 includes a rectifier 31, a switch 32 that is an example of the “first connection unit” of the present invention, and a load resistor 33. The rectifier 31 converts the AC power input from the connection 14 to the rotor winding into DC power by rectification. The switch 32 performs ON / OFF control of the electrical connection between the rectifier 31 and the load resistor 33 based on the crowbar circuit control signal supplied from the controller 40. In this embodiment, the switch 32 is provided in the subsequent stage of the rectifier 31 in the crowbar circuit 30. However, the switch 32 may be disposed in the previous stage of the rectifier 31 or may be disposed outside the crowbar circuit 30.

  The switch 32 is normally OFF and the load resistor 33 is disconnected from the connection 14 to the rotor winding. On the other hand, when iron resonance occurs, the switch 32 is turned on based on the crowbar circuit control signal from the controller 40, thereby connecting the load resistor 33 to the connection 14 to the rotor winding. An overvoltage or an overcurrent that occurs when it occurs can be reduced. Detailed operation control of the switch 32 will be described later.

  On the bus 13 of the wind power generator 1, selector switches SW <b> 1 and SW <b> 2 for switching the connection state of the output terminal of the generator 11 to the system connection end 6 are provided. The change-over switches SW1 and SW2 are normally in an ON state, and the electric power generated in the generator 11 is supplied to the electric power system 7 via the transformer 12 and the system linkage unit 4. . On the other hand, when iron resonance occurs, the changeover switches SW1 and SW2 are switched to the OFF state under a predetermined condition based on the disconnection control signal from the controller 40, so that the wind power generator 1 is disconnected from the power system 7. The wind power generator 1 can be prevented from being affected by iron resonance. Detailed operation control of the selector switches SW1 and SW2 will be described later.

  The grid interconnection unit 4 is a facility for linking the wind power generator 1 to the power grid 7, monitoring the supplied power based on the grid interconnection conditions defined with the power grid 7, and various types Make adjustments. For example, a condition for setting the power factor and output value at the interconnection point within the allowable range is set as the grid connection condition. The grid interconnection unit 4 may include a transformer 5.

  The electric power system 7 is a group of equipment that sends the output generated by the wind power generator 1 to consumers via transmission lines and substations, and includes other power generation facilities such as thermal power stations and general consumers.

  The auxiliary machine 70 operates by obtaining drive power from the bus 13, for example, a pitch drive mechanism for variably controlling the blade pitch of the wind power generator 1.

  Next, a specific operation of the wind power generation system 100 configured as described above will be described with reference to FIG. FIG. 3 is a flowchart showing the control contents of the wind power generation system 100 according to the first embodiment.

  First, the controller 40 detects iron resonance (step S101), and determines whether or not iron resonance has occurred (step S102). A specific iron resonance detection method will be described later.

  When the iron resonance has occurred (step S102: YES), the controller 40 switches the connection state of the switch 32 to ON by the crowbar circuit control signal, thereby connecting the load resistor 33 of the crowbar circuit 30 to the rotor winding 14. (Step S103). Thereby, the overvoltage or overcurrent caused by iron resonance can be reduced by the load resistor 33. If no iron resonance has occurred (step S102: NO), the controller 40 returns the process and executes steps S101 and S102) again.

  Thereafter, the controller 40 detects iron resonance again (step S104), and determines whether or not iron resonance has occurred (step S105). If the iron resonance has occurred (step S105: YES), the controller 40 repeats the detection of the iron resonance at a constant or indefinite period, so that the iron resonance duration Ta is greater than the first predetermined period T1. Is determined (step S106). Here, the first predetermined period T1 is a threshold value defined as a period required for the crowbar circuit 30 as the protection circuit to be in an overload state due to overpower generated by iron resonance.

  If the duration time Ta of the iron resonance is longer than the first predetermined period T1 (step S106: YES), the controller 40 switches the changeover switch SW1 or SW2 to the disconnected state (OFF) based on the disconnection control signal. The wind turbine generator 1 is disconnected from the power system 7 (step S107). Thereby, when iron resonance occurs over a long period of time, the wind power generator 1 is disconnected from the power system 7, thereby avoiding the crowbar circuit 30 serving as a protection circuit from falling into an overload state. It is possible to prevent a situation in which the adverse effect on the situation is not suppressed. On the other hand, when the duration time Ta of the iron resonance is equal to or shorter than the first predetermined period T1 (step S106: NO), the controller 40 returns the process to step S104 and re-executes the above process.

  Subsequently, when the iron resonance has not occurred (step S105: NO), the controller 40 determines whether or not the iron resonance disappearance period Tb is shorter than the second predetermined period T2 (step S108). Here, the second predetermined period T2 is a threshold value defined as a period required to determine whether or not the iron resonance has been completely eliminated. The generation condition of the iron resonance is caused by various factors, and depending on the condition, there may be an unstable behavior such as repeated generation and stop (that is, intermittent behavior). Therefore, in order to determine that the iron resonance has been completely eliminated by disconnecting the wind power generator 1, it is necessary to confirm that no iron resonance has occurred for a certain period of time. In the present embodiment, it is configured that it is determined that the iron resonance has been completely eliminated when no iron resonance occurs during the second predetermined period T2.

  When the iron resonance disappearance period Tb is shorter than the second predetermined period T2 (step S108: YES), the controller 40 determines that the iron resonance has not been completely eliminated and returns the process to step S106 to execute the above process. On the other hand, when the disappearance period Tb of the iron resonance is equal to or longer than the second predetermined period T2 (step S108: NO), the controller 40 switches the connection state of the switch 32 to OFF by the crowbar circuit control signal. The operation is terminated (step S109). As described above, the operation of the crowbar circuit 30 is terminated after the cancellation of the iron resonance is completely confirmed, thereby preventing the switch 32 from being complicatedly switched according to the iron resonance that occurs intermittently. it can.

  When the wind turbine generator 1 is disconnected from the power grid 7 in step S107, the controller 40 determines whether or not the iron resonance extinction period Tb is shorter than the second predetermined period T2, as in step S108. Step S110). Then, when the iron resonance disappearance period Tb is shorter than the second predetermined period T2 (step S110: YES), it is determined that the iron resonance has not been completely eliminated, and the wind power generator 1 is continuously disconnected. On the other hand, when the disappearance period Tb of the iron resonance is equal to or longer than the second predetermined period T2 (step S110: NO), the controller 40 determines that the iron resonance has completely disappeared and switches the switches SW1 and SW2 to the ON state. The wind power generator 1 is returned to the power system 7.

  In particular, since the changeover switches SW1 and SW2 are provided on the bus 13 which is a main power transmission line, generally large power flows. For this reason, if the switching operation is performed unnecessarily and the contact resistance increases, the amount of heat generated at the location increases, leading to failure. In view of this, in the present embodiment, it is possible to restore the wind power generator 1 at an early stage without unnecessarily increasing the switching operation of the changeover switches SW1 and SW2 and after the iron resonance is resolved.

  Note that when the wind turbine generator 1 is disconnected in step S107 of FIG. 3, it may be performed by switching the switch SW1 to the OFF state while maintaining the switch SW2 in the ON state. In this case, even when the wind turbine generator 1 is disconnected, the operation can be continued by continuing to supply drive power to the auxiliary machine 70 and the controller 40 from the power system side 7. Therefore, there is an advantage that the return operation after the iron resonance is canceled can be performed quickly.

Further, when the wind turbine generator 1 is disconnected in step S107 of FIG. 3, it may be performed by switching the switch SW2 to the OFF state while maintaining the switch SW1 in the ON state. In this case, since the wind turbine generator 1 is completely disconnected from the power system side 7, the wind turbine generator 1 can be more reliably protected from iron resonance.
In this case, by adopting connection means that can be operated remotely as the changeover switches SW1 and SW2, for example, driving power is supplied to the changeover switches SW1 and SW2 from an uninterruptible power supply (UPS) built in the wind power generator 1. Depending on, automatic control may be performed. As a result, it is not necessary to manually turn on the drive power again for the return operation after canceling the iron resonance, and the recovery operation can be automatically performed.
As an automatic control method for the changeover switches SW1 and SW2, the wind power generator 1 and the controller 40 can communicate with each other by the power supplied from the uninterruptible power supply (UPS) after the wind power generator 1 is disconnected. Keep it in a state. Thereby, when returning the wind power generator 1 at the above-mentioned timing, the control signals may be automatically output and controlled to the changeover switches SW1 and SW2.

  Next, the iron resonance detection method in steps S101 and S104 in FIG. 3 will be described in detail with reference to FIG. FIG. 4 is a flowchart showing the iron resonance detection method in steps S101 and S104 of FIG.

  The controller 40 acquires the voltage value from the transformer 12 with time (step S201), and calculates the magnetic flux Φ in the iron core constituting the transformer 12 from the time integral value of the acquired voltage value (step S202). . Then, it is determined whether or not the magnetic flux Φ calculated in step S202 exceeds a predetermined level value Φ1 defined in advance (step S203). When the magnetic flux Φ exceeds the predetermined level value Φ1 (step S203: YES), it is determined that iron resonance has occurred (step S204). On the other hand, when the magnetic flux Φ is equal to or less than the predetermined level value Φ1 (step S203: NO), it is determined that no iron resonance has occurred (step S205).

  The iron resonance is generated when the magnetic flux Φ in the iron core of the transformer 12 is saturated. In this embodiment, the presence or absence of iron resonance is detected by calculating the magnetic flux Φ included in the core from the voltage value of the transformer 12 and determining whether or not the magnetic flux Φ reaches the saturation magnetic flux Φ1. ing.

  The voltage value of the transformer 12 detected by the controller 40 may be on the primary winding side or the secondary winding side. Separately from the winding of the transformer 12, a magnetic flux detection coil may be wound around the iron core of the transformer 12, and the voltage generated in this coil may be integrated.

[Second Embodiment]
Next, with reference to FIG.5 and FIG.6, the wind power generation system 100 which concerns on 2nd Embodiment is demonstrated. FIG. 5 is a block diagram conceptually showing the overall configuration of the wind power generation system 100 according to the second embodiment, and FIG. 6 is a flowchart showing a method for detecting iron resonance in the wind power generation system 100 according to the second embodiment. is there. In addition, the same code | symbol shall be shown to the location which is common in the said 1st Example, and detailed description is abbreviate | omitted.

  As shown in FIG. 5, in the wind power generation system according to the second embodiment, the magnetic sensor 50 disposed near the core of the transformer 12 is provided, and the controller 40 acquires a signal from the magnetic sensor 50. Thus, the leakage flux ΦL in the transformer 12 can be detected. As the magnetic sensor 50, various magnetic sensors such as a Hall element and a Faraday element can be used.

  As shown in FIG. 6, the controller 40 acquires the leakage flux ΦL of the transformer 12 from the magnetic sensor 50 over time (step S301). Then, it is determined whether or not the acquired leakage magnetic flux ΦL exceeds a predetermined level value ΦL1 defined in advance (step S302). If the leakage flux ΦL exceeds the predetermined level value ΦL1 (step S302: YES), the controller 40 determines that iron resonance has occurred (step S303). On the other hand, when the leakage flux ΦL is equal to or lower than the predetermined level value ΦlL (step S302: NO), the controller 40 determines that no iron resonance has occurred (step S304).

  As described above, the iron resonance occurs at the timing when the magnetic flux Φ included in the core of the transformer 12 is saturated. In other words, when iron resonance occurs, the magnetic flux Φ of the iron core of the transformer 12 is saturated and the leakage magnetic flux ΦL increases. Therefore, in this embodiment, the leakage flux ΦL is detected by a magnetic sensor, and the presence or absence of iron resonance can be determined according to whether or not the leakage flux ΦL has reached a predetermined level value ΦL1.

[Third embodiment]
Next, a wind power generation system 100 according to a third embodiment will be described with reference to FIG. FIG. 7 is a block diagram conceptually showing the overall structure of the wind power generation system 100 according to the third embodiment. In addition, the same code | symbol shall be shown to the location which is common in the said 1st Example, and detailed description is abbreviate | omitted.

  The controller 40 acquires a voltage waveform or a current waveform from the transformer 12 via the low-pass filter 60 for extracting a low frequency component, and when the acquired low frequency component exceeds a predetermined level value, occurrence of iron resonance Is detected. Thereby, the iron resonance having a frequency lower than the commercial fundamental frequency can be detected with high reliability. Particularly in the present embodiment, the iron resonance can be detected only by adding a simple component such as the low-pass filter 60. Therefore, highly reliable detection of iron resonance can be realized while effectively preventing the system from becoming complicated.

[Fourth embodiment]
Next, with reference to FIG. 8, the wind power generation system 100 which concerns on 4th Embodiment is demonstrated. FIG. 8 is a block diagram conceptually showing the overall structure of the wind power generation system 100 according to the fourth embodiment. In addition, the same code | symbol shall be shown to the part which is common in the said 1st Example and 2nd Example, and detailed description is abbreviate | omitted.

  As shown in FIG. 8, in the wind power generation system 100 according to the fourth embodiment, a plurality of wind power generation devices 1 (in FIG. 8, each wind power generation device is indicated by 1a, 1b,...) Are parallel to each other. A plurality (m in total) of connected groups G1 to Gm are provided, and each group G1 to Gm is connected to the power system 7 through a substation 80 and a compensation capacitor 90 inserted in series. Has been. In the present embodiment, the above-described controller 40 is included in the substation 8 (in FIG. 8, the controller 40 is not shown because it is built in the substation 80), and the current from the transformer 5 is The occurrence of iron resonance can be detected by monitoring the value or voltage value. That is, in this embodiment, the occurrence of iron resonance in each wind power generator 1 constituting each group G <b> 1 to Gm can be collectively monitored by the substation 80. Thus, the monitoring of the iron resonance in the plurality of wind turbine generators 1 can be realized with a simple configuration without monitoring each wind turbine generator 1 individually. Note that communication means (not shown) is provided from the substation 80 to the individual wind power generator 1, thereby notifying the individual wind power generator 1 of the occurrence of iron resonance. When generation | occurrence | production of iron resonance is notified, in the separate wind power generator 1, protection operation | movement is performed according to the example of the said Examples 1-3.

[Fifth embodiment]
Next, a wind power generation system 100 according to the fifth embodiment will be described with reference to FIG. FIG. 9 is a flowchart showing the control contents of the wind power generation system 100 according to the fifth embodiment. In addition, about the structure of the wind power generation system 100 which concerns on 5th Example, it is the same as that of the said 4th Example (refer FIG. 8).

  In the wind power generation system 100 according to the fifth example, provided in the substation 80 when iron resonance is detected over the first predetermined period T1 or more following the control in steps S106 and S107 of FIG. By disconnecting the groups G1 to Gm from the electric power system 7 by the breakers SW11 to SW1m, it is possible to prevent the wind power generator 1 from being adversely affected by iron resonance. The group disconnection control of the groups G1 to Gm is basically the same as the group disconnection control of the wind turbine generator 1 in FIG. 3, but in this embodiment, the groups G1 to Gm are particularly selected until the iron resonance is resolved. It is characterized in that it is disconnected from the power system 7 at predetermined time intervals one by one.

  As shown in FIG. 9, in the disconnection control of each of the groups G1 to Gm, when disconnecting according to step S107, first, the variable m is set to “1” (step S401), and the circuit breaker SW11 is turned off. Only the group G1 is disconnected from the power system 7 by switching (step S402). Thereafter, it is determined whether or not the iron resonance has been resolved (step S403). If it is determined that the iron resonance has not been resolved (step S403: NO), “m + 1” is substituted for the variable m (step S404). The above process is repeated. As a result, the m groups G1 to Gm are sequentially disconnected from the power system one by one until the iron resonance is resolved. Then, when the iron resonance is resolved (step S403: YES), the separation of the groups G1 to Gm is terminated (step S405), and the process is terminated (END). As a result, it is not necessary to disconnect all of the groups G1 to Gm at a time, so that only a part of the groups are disconnected in order to prevent iron resonance, and power is generated in the remaining groups to generate the power system 7. The power supply can be continued.

In the present embodiment, in particular, by providing the breaker 1m on the substation 80 side, each group G1 to Gm can be completely disconnected from the power system 7 side individually. It can protect more reliably.
In this case, similarly to the change-over switches SW1 and SW2 in the first embodiment, by adopting connection means that can be operated remotely as the circuit breaker 1m, for example, it is disconnected from the uninterruptible power supply (UPS) built in the wind power generator 1 Automatic control may be performed by supplying driving power to the machine 1m. As a result, it is not necessary to manually turn on the drive power again for the return operation after canceling the iron resonance, and the recovery operation can be automatically performed.

  Also in the present embodiment, the switches may be disconnected by controlling the changeover switches (SW1 and SW2 shown in FIG. 1) provided on the wind power generator 1 side. In this case, as described in the first embodiment, even when the wind turbine generator 1 is disconnected, the auxiliary machine 70 and the controller 40 are continuously supplied with driving power from the power system side 7 to continue the operation. Can do. Therefore, there is an advantage that the return operation after the iron resonance is canceled can be performed quickly.

  Further, in this embodiment, the iron resonance is detected in the substation 80. In accordance with this, as described in the first embodiment, the individual wind power generators 1 included in the groups G1 to Gm are also used. Detection of iron resonance may be performed. In this case, it is preferable to compare the detection timing of the iron resonance in the substation 80 with the detection timing of the iron resonance in each wind power generator 1 and control the above-described protection operation according to the earlier timing. As a result, the protection operation can be executed more quickly, so that the safety of the system can be improved more effectively.

  In addition, when the suppression of iron resonance is insufficient even by the above-described protection operation, the circuit breaker SW3 provided on the power system 7 side of the substation 80 may be switched to the OFF state. As a result, the substation 80 side can be completely isolated from the power system 7, so that the protection of the substation 80 is ensured, and the iron resonance suppression effect due to the change in the circuit conditions of the entire system is further improved. Can be obtained effectively.

  As described above, according to the wind power generation system 100 of the present invention, the crowbar circuit 30 is connected to the wind power generator 1 by controlling the switch 32 when iron resonance is detected. Thereby, by reducing the overvoltage or overcurrent caused by the iron resonance in the crowbar circuit 30, it is possible to prevent an adverse effect on the wind turbine generator 1. Further, after the crowbar circuit 30 is connected, when the iron resonance is detected over the first predetermined period T1 or more, the wind turbine generator 1 is disconnected from the power system 7 by controlling the changeover switches SW1 and SW2. To do. As a result, even when iron resonance occurs over a long period of time, the wind power generator 1 itself is disconnected from the power system 7 to avoid the crowbar circuit 30 from falling into an overload state. 1 can be protected.

  INDUSTRIAL APPLICABILITY The present invention can be used for a control method and a control device for a wind power generation system that supplies power generated by a wind power generation device to a power system via a transformer.

DESCRIPTION OF SYMBOLS 1 Wind power generator 4 Grid connection part 5 Transformer 6 System connection end 7 Electric power system 11 Generator 12 Transformer 13 Bus 30 Clover circuit 31 Rectifier 32 Switch (1st switching means)
33 Load resistance 40 Controller 50 Magnetic sensor 60 Low-pass filter 70 Auxiliary machine 80 Substation 100 Wind power generation system SW1, SW2 selector switch (second switching means)
SW3 Breaker G1-Gm Group SW11-SW1m Breaker

Claims (10)

A method for controlling a wind power generation system that supplies power generated by a wind power generator to an electric power system via a transformer,
A detection step of detecting the occurrence of iron resonance in the transformer;
A protection circuit connecting step of connecting a protection circuit for reducing overvoltage or current generated by iron resonance to the wind power generator when iron resonance is detected;
And a disconnecting step of disconnecting the wind power generator from the power system when an iron resonance is detected over a first predetermined period after the protection circuit is connected to the wind power generator. A method for controlling a wind power generation system.   After disconnecting the wind power generator from the power system, when the iron resonance is not detected for a second predetermined period or longer, the reverse power is returned to the power system. The method according to claim 1, further comprising a step.   The detection step calculates the magnetic flux from the time integral value of the voltage applied to the transformer, and detects the occurrence of iron resonance when the magnetic flux exceeds a predetermined level value. A control method of the described wind power generation system.   The method for controlling a wind power generation system according to claim 3, wherein the voltage applied to the transformer is a voltage generated by winding a magnetic flux detection coil around the iron core of the transformer.   3. The detection according to claim 1, wherein the detecting step detects a leakage magnetic flux in the transformer, and detects the occurrence of iron resonance when the detected leakage magnetic flux exceeds a predetermined level value. 4. Wind power generation system control method.   The detecting step extracts a low-frequency component of a voltage waveform or a current waveform in the transformer transformer through a low-pass filter, and detects the occurrence of iron resonance when the output waveform of the low-pass filter exceeds a predetermined level value. The method for controlling a wind power generation system according to claim 1 or 2.   7. The wind power generation system according to claim 1, wherein a plurality of the wind power generation devices connected in parallel to each other are connected to the power system via the transformer. The method for controlling a wind power generation system according to the item.   In the disconnecting step, when the iron resonance is detected by the detecting means over the first predetermined period or longer, the plurality of wind turbine generators are predetermined one by one until the iron resonance is eliminated. The method of controlling a wind power generation system according to claim 7, wherein the power system is disconnected from the power system every time. A control device for a wind power generation system that supplies power generated by a wind power generation device to a power system via a transformer,
Detecting means for detecting the occurrence of iron resonance in the transformer;
A first connection means for switching a connection state of the protection circuit capable of suppressing overvoltage or current generated by iron resonance by being connected to the wind power generator;
Second connection means for switching a connection state of the wind power generator to the power system;
When the iron resonance is detected by the detection means, the first connection means is controlled to connect the protection circuit to the wind power generator, and thereafter, the iron resonance is detected by the detection means for a first predetermined period. A control device for a wind power generation system, comprising: control means for controlling the second connection means so that the wind power generation device is disconnected from the power system when detected over the above. The wind power generation system is configured such that a plurality of wind power generation devices connected in parallel to each other are connected to the power system via the transformer,
When the iron resonance is detected for the first predetermined period or more by the detection means, the control means sets the plurality of wind power generators one by one every predetermined time until the iron resonance is canceled. The control device for a wind power generation system according to claim 9, wherein the second connection unit is controlled so as to be disconnected from the power system.

Images